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  • Question 1 - A young woman presents with sudden palpitations and difficulty breathing, and her ECG...

    Correct

    • A young woman presents with sudden palpitations and difficulty breathing, and her ECG reveals tachycardia. Which cardiac component typically experiences the most rapid depolarization?

      Your Answer: Sino-atrial node

      Explanation:

      The heart’s conducting system is made up of specialized cardiac muscle cells and fibers that generate and rapidly transmit action potentials. This system is crucial for coordinating the contractions of the heart’s chambers during the cardiac cycle. When this system malfunctions due to conduction blockages or abnormal action potential sources, it can lead to arrhythmias.

      The conducting system has five main components:

      1. The sino-atrial (SAN) node, located in the right atrium, generates electrical signals.
      2. These signals stimulate the atria to contract and travel to the atrio-ventricular (AVN) node in the interatrial septum.
      3. After a delay, the stimulus diverges and is conducted through the left and right bundle of His.
      4. The conduction then passes to the respective Purkinje fibers for each side of the heart.
      5. Finally, the electrical signals reach the endocardium at the apex of the heart and the ventricular epicardium.

      Understanding the Cardiac Action Potential and Conduction Velocity

      The cardiac action potential is a series of electrical events that occur in the heart during each heartbeat. It is responsible for the contraction of the heart muscle and the pumping of blood throughout the body. The action potential is divided into five phases, each with a specific mechanism. The first phase is rapid depolarization, which is caused by the influx of sodium ions. The second phase is early repolarization, which is caused by the efflux of potassium ions. The third phase is the plateau phase, which is caused by the slow influx of calcium ions. The fourth phase is final repolarization, which is caused by the efflux of potassium ions. The final phase is the restoration of ionic concentrations, which is achieved by the Na+/K+ ATPase pump.

      Conduction velocity is the speed at which the electrical signal travels through the heart. The speed varies depending on the location of the signal. Atrial conduction spreads along ordinary atrial myocardial fibers at a speed of 1 m/sec. AV node conduction is much slower, at 0.05 m/sec. Ventricular conduction is the fastest in the heart, achieved by the large diameter of the Purkinje fibers, which can achieve velocities of 2-4 m/sec. This allows for a rapid and coordinated contraction of the ventricles, which is essential for the proper functioning of the heart. Understanding the cardiac action potential and conduction velocity is crucial for diagnosing and treating heart conditions.

    • This question is part of the following fields:

      • Cardiovascular System
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  • Question 2 - A 26-year-old man presents to the emergency department after experiencing a syncopal episode....

    Incorrect

    • A 26-year-old man presents to the emergency department after experiencing a syncopal episode. He is currently stable and reports no warning signs prior to the episode. He has had a few similar episodes in the past but did not seek medical attention. Upon further investigation, it is discovered that his father and uncle both died suddenly from heart attacks at ages 45 and 42, respectively. An ECG reveals coved ST segment elevation in V1 and V2 leads, followed by a negative T wave. What is the definitive treatment for this patient's condition?

      Your Answer:

      Correct Answer: Implantable cardioverter-defibrillator

      Explanation:

      The most effective management for Brugada syndrome is the implantation of a cardioverter-defibrillator, as per the NICE guidelines. This is the recommended treatment for patients with the condition, as evidenced by this man’s ECG findings, syncopal episodes, and family history of sudden cardiac deaths.

      While class I antiarrhythmic drugs like flecainide and procainamide may be used in clinical settings to diagnose Brugada syndrome, they should be avoided in patients with the condition as they can transiently induce the ECG features of the syndrome.

      Quinidine, another class I antiarrhythmic drug, has shown some benefits in preventing and treating tachyarrhythmias in small studies of patients with Brugada syndrome. However, it is not a definitive treatment and has not been shown to reduce the rate of sudden cardiac deaths in those with the condition.

      Amiodarone is typically used in life-threatening situations to stop ventricular tachyarrhythmias. However, due to its unfavorable side effect profile, it is not recommended for long-term use, especially in younger patients who may require it for decades.

      Understanding Brugada Syndrome

      Brugada syndrome is a type of inherited cardiovascular disease that can lead to sudden cardiac death. It is passed down in an autosomal dominant manner and is more prevalent in Asians, with an estimated occurrence of 1 in 5,000-10,000 individuals. The condition has a variety of genetic variants, but around 20-40% of cases are caused by a mutation in the SCN5A gene, which encodes the myocardial sodium ion channel protein.

      One of the key diagnostic features of Brugada syndrome is the presence of convex ST segment elevation greater than 2mm in more than one of the V1-V3 leads, followed by a negative T wave and partial right bundle branch block. These ECG changes may become more apparent after the administration of flecainide or ajmaline, which are the preferred diagnostic tests for suspected cases of Brugada syndrome.

      The management of Brugada syndrome typically involves the implantation of a cardioverter-defibrillator to prevent sudden cardiac death. It is important for individuals with Brugada syndrome to receive regular medical monitoring and genetic counseling to manage their condition effectively.

    • This question is part of the following fields:

      • Cardiovascular System
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  • Question 3 - A 65-year-old male with chronic cardiac failure visits his doctor and reports experiencing...

    Incorrect

    • A 65-year-old male with chronic cardiac failure visits his doctor and reports experiencing dyspnoea even with minimal physical exertion, and only feeling comfortable when at rest. What class of the New York Heart Association scale does he fall under?

      Your Answer:

      Correct Answer: III

      Explanation:

      The NYHA Scale for Cardiac Failure Patients

      The NYHA scale is a tool used to standardize the description of the severity of cardiac failure patients. It classifies patients into four categories based on their symptoms and limitations of activities. Class I patients have no limitations and do not experience any symptoms during ordinary activities. Class II patients have mild limitations and are comfortable with rest or mild exertion. Class III patients have marked limitations and are only comfortable at rest. Finally, Class IV patients should be at complete rest and are confined to bed or chair. Any physical activity brings discomfort and symptoms occur even at rest.

      The NYHA scale is an important tool for healthcare professionals to assess the severity of cardiac failure in patients. It helps to determine the appropriate treatment plan and level of care needed for each patient. By using this scale, healthcare professionals can communicate more effectively with each other and with patients about the severity of their condition. It also helps patients to understand their limitations and adjust their activities accordingly. Overall, the NYHA scale is a valuable tool in the management of cardiac failure patients.

    • This question is part of the following fields:

      • Cardiovascular System
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  • Question 4 - A 67-year-old man is brought to the emergency department with unilateral weakness and...

    Incorrect

    • A 67-year-old man is brought to the emergency department with unilateral weakness and loss of sensation. He is later diagnosed with an ischaemic stroke. After initial treatment, he is started on dipyridamole as part of his ongoing therapy.

      What is the mechanism of action of dipyridamole?

      Your Answer:

      Correct Answer: Non-specific phosphodiesterase inhibitor

      Explanation:

      Understanding the Mechanism of Action of Dipyridamole

      Dipyridamole is a medication that is commonly used in combination with aspirin to prevent the formation of blood clots after a stroke or transient ischemic attack. The drug works by inhibiting phosphodiesterase, which leads to an increase in the levels of cyclic adenosine monophosphate (cAMP) in platelets. This, in turn, reduces the levels of intracellular calcium, which is necessary for platelet activation and aggregation.

      Apart from its antiplatelet effects, dipyridamole also reduces the cellular uptake of adenosine, a molecule that plays a crucial role in regulating blood flow and oxygen delivery to tissues. By inhibiting the uptake of adenosine, dipyridamole can increase its levels in the bloodstream, leading to vasodilation and improved blood flow.

      Another mechanism of action of dipyridamole is the inhibition of thromboxane synthase, an enzyme that is involved in the production of thromboxane A2, a potent platelet activator. By blocking this enzyme, dipyridamole can further reduce platelet activation and aggregation, thereby preventing the formation of blood clots.

      In summary, dipyridamole exerts its antiplatelet effects through multiple mechanisms, including the inhibition of phosphodiesterase, the reduction of intracellular calcium levels, the inhibition of thromboxane synthase, and the modulation of adenosine uptake. These actions make it a valuable medication for preventing thrombotic events in patients with a history of stroke or transient ischemic attack.

    • This question is part of the following fields:

      • Cardiovascular System
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  • Question 5 - A 57-year-old man comes to see his doctor with concerns about his sexual...

    Incorrect

    • A 57-year-old man comes to see his doctor with concerns about his sexual relationship with his new wife. Upon further inquiry, he discloses that he is experiencing difficulty in achieving physical arousal and is experiencing delayed orgasms. He did not report any such issues during his medication review six weeks ago and believes that the recent change in medication may be responsible for this.

      The patient's medical history includes asthma, hypertension, migraine, bilateral hip replacement, and gout.

      Which medication is the most likely cause of his recent prescription change?

      Your Answer:

      Correct Answer: Indapamide

      Explanation:

      Thiazide-like diuretics, including indapamide, can cause sexual dysfunction, which is evident in this patient’s history. Before attempting to manage the issue, it is important to rule out any iatrogenic causes. Ramipril, an ACE-inhibitor, is not associated with sexual dysfunction, while losartan, an angiotensin II receptor blocker, and amlodipine, a dihydropyridine calcium channel blocker, are also not known to cause sexual dysfunction and are used in the management of hypertension.

      Thiazide diuretics are medications that work by blocking the thiazide-sensitive Na+-Cl− symporter, which inhibits sodium reabsorption at the beginning of the distal convoluted tubule (DCT). This results in the loss of potassium as more sodium reaches the collecting ducts. While thiazide diuretics are useful in treating mild heart failure, loop diuretics are more effective in reducing overload. Bendroflumethiazide was previously used to manage hypertension, but recent NICE guidelines recommend other thiazide-like diuretics such as indapamide and chlorthalidone.

      Common side effects of thiazide diuretics include dehydration, postural hypotension, and electrolyte imbalances such as hyponatremia, hypokalemia, and hypercalcemia. Other potential adverse effects include gout, impaired glucose tolerance, and impotence. Rare side effects may include thrombocytopenia, agranulocytosis, photosensitivity rash, and pancreatitis.

      It is worth noting that while thiazide diuretics may cause hypercalcemia, they can also reduce the incidence of renal stones by decreasing urinary calcium excretion. According to current NICE guidelines, the management of hypertension involves the use of thiazide-like diuretics, along with other medications and lifestyle changes, to achieve optimal blood pressure control and reduce the risk of cardiovascular disease.

    • This question is part of the following fields:

      • Cardiovascular System
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  • Question 6 - Evelyn is a 92-year-old woman who arrives at the hospital with severe chest...

    Incorrect

    • Evelyn is a 92-year-old woman who arrives at the hospital with severe chest pain, shortness of breath, and palpitations. Given her medical history of angina and diabetes mellitus, doctors suspect acute coronary syndrome. They order several tests, including a troponin I blood test. What is the function of this biomarker in the body?

      Your Answer:

      Correct Answer: Binds to actin to hold the troponin-tropomyosin complex in place

      Explanation:

      Troponin I plays a crucial role in muscle contraction by binding to actin and holding the troponin-tropomyosin complex in place. This prevents the myosin-binding site on the actin from being exposed, thereby preventing muscle contraction. Troponin I is also used as a marker for myocardial muscle injury.

      Unlike troponin C, troponin I does not bind to calcium. Instead, troponin C has several calcium-binding sites that, when occupied, cause a conformational change in the troponin-tropomyosin complex. This change exposes the myosin-binding site on the actin filament, allowing myosin to bind and initiate muscle contraction.

      Although troponin I binds to actin, it does not perform the power stroke that shortens muscle fibers. This is the role of the myosin head, which uses energy from ATP.

      It is troponin T, not troponin I, that binds with tropomyosin to form the troponin-tropomyosin complex. This complex allows tropomyosin to move in response to the conformational change induced by calcium binding to troponin C.

      Finally, it is tropomyosin, not troponin I, that directly inhibits myosin-binding sites. Tropomyosin is a long fiber that runs along the side of actin filaments, blocking all myosin binding sites. When calcium concentrations within the cell increase, the conformational change in troponin moves tropomyosin, exposing these sites and allowing muscle contraction to occur.

      Understanding Troponin: The Proteins Involved in Muscle Contraction

      Troponin is a group of three proteins that play a crucial role in the contraction of skeletal and cardiac muscles. These proteins work together to regulate the interaction between actin and myosin, which is essential for muscle contraction. The three subunits of troponin are troponin C, troponin T, and troponin I.

      Troponin C is responsible for binding to calcium ions, which triggers the contraction of muscle fibers. Troponin T binds to tropomyosin, forming a complex that helps regulate the interaction between actin and myosin. Finally, troponin I binds to actin, holding the troponin-tropomyosin complex in place and preventing muscle contraction when it is not needed.

      Understanding the role of troponin is essential for understanding how muscles work and how they can be affected by various diseases and conditions. By regulating the interaction between actin and myosin, troponin plays a critical role in muscle contraction and is a key target for drugs used to treat conditions such as heart failure and skeletal muscle disorders.

    • This question is part of the following fields:

      • Cardiovascular System
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  • Question 7 - The cephalic vein penetrates the clavipectoral fascia to end in which of the...

    Incorrect

    • The cephalic vein penetrates the clavipectoral fascia to end in which of the following veins mentioned below?

      Your Answer:

      Correct Answer: Axillary

      Explanation:

      The Cephalic Vein: Path and Connections

      The cephalic vein is a major blood vessel that runs along the lateral side of the arm. It begins at the dorsal venous arch, which drains blood from the hand and wrist, and travels up the arm, crossing the anatomical snuffbox. At the antecubital fossa, the cephalic vein is connected to the basilic vein by the median cubital vein. This connection is commonly used for blood draws and IV insertions.

      After passing through the antecubital fossa, the cephalic vein continues up the arm and pierces the deep fascia of the deltopectoral groove to join the axillary vein. This junction is located near the shoulder and marks the end of the cephalic vein’s path.

      Overall, the cephalic vein plays an important role in the circulation of blood in the upper limb. Its connections to other major veins in the arm make it a valuable site for medical procedures, while its path through the deltopectoral groove allows it to contribute to the larger network of veins that drain blood from the upper body.

    • This question is part of the following fields:

      • Cardiovascular System
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  • Question 8 - A 48-year-old man visits his local doctor complaining of chest pain that occurs...

    Incorrect

    • A 48-year-old man visits his local doctor complaining of chest pain that occurs during physical activity and subsides with rest. He first noticed it 10 months ago and feels that it has gradually worsened. He now experiences this pain while climbing a few stairs. Previously, he could walk down to the newsagent and back, a distance of 200 yards, without any discomfort. He has a medical history of hypertension and appendectomy.

      His close friend had similar symptoms that were relieved by sublingual glyceryl nitrates. He asks the doctor to prescribe something similar.

      What is the mechanism by which nitrates work?

      Your Answer:

      Correct Answer: Nitrates cause a decrease in intracellular calcium which results in smooth muscle relaxation

      Explanation:

      The reason why nitrates cause a decrease in intracellular calcium is because nitric oxide triggers the activation of smooth muscle soluble guanylyl cyclase (GC) to produce cGMP. This increase in intracellular cGMP inhibits calcium entry into the cell, resulting in a reduction in intracellular calcium levels and inducing smooth muscle relaxation. Additionally, nitric oxide activates K+ channels, leading to hyperpolarization and relaxation. Furthermore, nitric oxide stimulates a cGMP-dependent protein kinase that activates myosin light chain phosphatase, which dephosphorylates myosin light chains, ultimately leading to relaxation. Therefore, the correct answer is the second option.

      Understanding Nitrates and Their Effects on the Body

      Nitrates are a type of medication that can cause blood vessels to widen, which is known as vasodilation. They are commonly used to manage angina and treat heart failure. One of the most frequently prescribed nitrates is sublingual glyceryl trinitrate, which is used to relieve angina attacks in patients with ischaemic heart disease.

      The mechanism of action for nitrates involves the release of nitric oxide in smooth muscle, which activates guanylate cyclase. This enzyme then converts GTP to cGMP, leading to a decrease in intracellular calcium levels. In the case of angina, nitrates dilate the coronary arteries and reduce venous return, which decreases left ventricular work and reduces myocardial oxygen demand.

      However, nitrates can also cause side effects such as hypotension, tachycardia, headaches, and flushing. Additionally, many patients who take nitrates develop tolerance over time, which can reduce their effectiveness. To combat this, the British National Formulary recommends that patients who develop tolerance take the second dose of isosorbide mononitrate after 8 hours instead of 12 hours. This allows blood-nitrate levels to fall for 4 hours and maintains effectiveness. It’s important to note that this effect is not seen in patients who take modified release isosorbide mononitrate.

    • This question is part of the following fields:

      • Cardiovascular System
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  • Question 9 - A 63-year-old man comes to the emergency department complaining of severe crushing chest...

    Incorrect

    • A 63-year-old man comes to the emergency department complaining of severe crushing chest pain that radiates to his jaw and is accompanied by profuse sweating and nausea. Upon conducting an ECG, you observe ST-segment elevation in leads V2-V4, leading you to diagnose an anteroseptal ST-elevation myocardial infarction (MI). Can you identify the coronary vessel that runs along the interventricular septum on the anterior surface of the heart to reach the apex?

      Your Answer:

      Correct Answer: Left anterior descending artery

      Explanation:

      The coronary arteries supply blood to the heart muscle, and blockages in these arteries can lead to heart attacks. The right coronary artery supplies the right side of the heart and is often associated with arrhythmias when blocked. The left circumflex artery supplies the left side of the heart and can cause lateral, posterior, or anterolateral heart attacks when blocked. The right marginal artery arises from the right coronary artery and travels along the bottom of the heart, while the left marginal artery arises from the left circumflex artery and travels along the curved edge of the heart.

      The walls of each cardiac chamber are made up of the epicardium, myocardium, and endocardium. The heart and roots of the great vessels are related anteriorly to the sternum and the left ribs. The coronary sinus receives blood from the cardiac veins, and the aortic sinus gives rise to the right and left coronary arteries. The left ventricle has a thicker wall and more numerous trabeculae carnae than the right ventricle. The heart is innervated by autonomic nerve fibers from the cardiac plexus, and the parasympathetic supply comes from the vagus nerves. The heart has four valves: the mitral, aortic, pulmonary, and tricuspid valves.

    • This question is part of the following fields:

      • Cardiovascular System
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  • Question 10 - A 50-year-old man is brought to the acute medical ward with red flag...

    Incorrect

    • A 50-year-old man is brought to the acute medical ward with red flag sepsis, possibly originating from the urinary tract. Upon arrival, his blood pressure is recorded as 90/60mmHg, and he exhibits cool, mottled skin peripherally. To increase his preload and stroke volume, a fluid bolus is administered. What other physiological parameter is likely to be observed?

      Your Answer:

      Correct Answer: Increased pulse pressure

      Explanation:

      When stroke volume increases, pulse pressure also increases. This is important to consider in the management of shock, where intravenous fluids can increase preload and stroke volume. Factors that affect stroke volume include preload, cardiac contractility, and afterload. Pulse pressure can be calculated by subtracting diastolic blood pressure from systolic blood pressure.

      Decreased cardiac output is not a result of increased stroke volume, as cardiac output is calculated by multiplying stroke volume by heart rate. An increase in stroke volume would actually lead to an increase in cardiac output.

      Similarly, decreased mean arterial pressure is not a result of increased stroke volume, as mean arterial pressure is calculated by multiplying cardiac output by total peripheral resistance. An increase in stroke volume would lead to an increase in mean arterial pressure.

      Lastly, increased heart rate is not a direct result of increased stroke volume, as heart rate is calculated by dividing cardiac output by stroke volume. An increase in stroke volume would actually lead to a decrease in heart rate.

      Cardiovascular physiology involves the study of the functions and processes of the heart and blood vessels. One important measure of heart function is the left ventricular ejection fraction, which is calculated by dividing the stroke volume (the amount of blood pumped out of the left ventricle with each heartbeat) by the end diastolic LV volume (the amount of blood in the left ventricle at the end of diastole) and multiplying by 100%. Another key measure is cardiac output, which is the amount of blood pumped by the heart per minute and is calculated by multiplying stroke volume by heart rate.

      Pulse pressure is another important measure of cardiovascular function, which is the difference between systolic pressure (the highest pressure in the arteries during a heartbeat) and diastolic pressure (the lowest pressure in the arteries between heartbeats). Factors that can increase pulse pressure include a less compliant aorta (which can occur with age) and increased stroke volume.

      Finally, systemic vascular resistance is a measure of the resistance to blood flow in the systemic circulation and is calculated by dividing mean arterial pressure (the average pressure in the arteries during a heartbeat) by cardiac output. Understanding these measures of cardiovascular function is important for diagnosing and treating cardiovascular diseases.

    • This question is part of the following fields:

      • Cardiovascular System
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  • Question 11 - A 57-year-old man presents to the emergency department with a severe headache that...

    Incorrect

    • A 57-year-old man presents to the emergency department with a severe headache that started 3 weeks ago and is localised to the back of the head. He rates it 8/10 on a pain scale and reports that it has gradually become worse. The patient has a medical history of Ehlers-Danlos syndrome.

      Unfortunately, the patient passes away after suffering a brainstem stroke.

      During the autopsy, a vertebral artery dissection is discovered at the point of entry into the cranial cavity.

      Where is this location?

      Your Answer:

      Correct Answer: Foramen magnum

      Explanation:

      The vertebral arteries pass through the foramen magnum to enter the cranial cavity.

      Other foramina and their corresponding arteries include the stylomastoid foramen for the posterior auricular artery (stylomastoid branch), the foramen ovale for the accessory meningeal artery, and the foramen spinosum for the middle meningeal artery.

      The Circle of Willis is an anastomosis formed by the internal carotid arteries and vertebral arteries on the bottom surface of the brain. It is divided into two halves and is made up of various arteries, including the anterior communicating artery, anterior cerebral artery, internal carotid artery, posterior communicating artery, and posterior cerebral arteries. The circle and its branches supply blood to important areas of the brain, such as the corpus striatum, internal capsule, diencephalon, and midbrain.

      The vertebral arteries enter the cranial cavity through the foramen magnum and lie in the subarachnoid space. They then ascend on the anterior surface of the medulla oblongata and unite to form the basilar artery at the base of the pons. The basilar artery has several branches, including the anterior inferior cerebellar artery, labyrinthine artery, pontine arteries, superior cerebellar artery, and posterior cerebral artery.

      The internal carotid arteries also have several branches, such as the posterior communicating artery, anterior cerebral artery, middle cerebral artery, and anterior choroid artery. These arteries supply blood to different parts of the brain, including the frontal, temporal, and parietal lobes. Overall, the Circle of Willis and its branches play a crucial role in providing oxygen and nutrients to the brain.

    • This question is part of the following fields:

      • Cardiovascular System
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  • Question 12 - A 79-year-old man has just noticed that his heart is beating irregularly. Upon...

    Incorrect

    • A 79-year-old man has just noticed that his heart is beating irregularly. Upon examination, his pulse is found to be irregularly irregular with a rate of 56 bpm. What ECG findings would you anticipate?

      Your Answer:

      Correct Answer: No P wave preceding each QRS complex

      Explanation:

      Atrial Fibrillation and its Causes

      Atrial fibrillation (AF) is a condition characterized by irregular heartbeats due to the constant activity of the atria. This can lead to the absence of distinct P waves, making it difficult to diagnose. AF can be caused by various factors such as hyperthyroidism, alcohol excess, mitral stenosis, and fibrous degeneration. The primary risks associated with AF are strokes and cardiac failure. Blood clots can form in the atria due to the lack of atrial movement, which can then be distributed into the systemic circulation, leading to strokes. High rates of AF can also cause syncopal episodes and cardiac failure.

      The treatment of AF can be divided into controlling the rate or rhythm. If the rhythm cannot be controlled reliably, long-term anticoagulation with warfarin may be necessary to reduce the risk of stroke, depending on other risk factors. Bifid P waves are associated with hypertrophy of the left atrium, while regular P waves with no relation to QRS complexes are seen in complete heart block. Small P waves can be seen in hypokalaemia.

      In cases of AF with shock, immediate medical attention is necessary, and emergency drug or electronic cardioversion may be needed. the causes and risks associated with AF is crucial in managing the condition and preventing complications.

    • This question is part of the following fields:

      • Cardiovascular System
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  • Question 13 - A 50-year-old man is brought to the emergency department following a collapse on...

    Incorrect

    • A 50-year-old man is brought to the emergency department following a collapse on the street. Upon examination, he displays visual and oculomotor deficits, but his motor function remains intact. Digital subtraction angiography reveals a basilar artery occlusion at the point where the vertebral arteries merge to form the basilar artery. What anatomical feature corresponds to the location of the occlusion?

      Your Answer:

      Correct Answer: The base of the pons

      Explanation:

      The basilar artery is formed by the union of the vertebral arteries at the base of the pons.

      The Circle of Willis is an anastomosis formed by the internal carotid arteries and vertebral arteries on the bottom surface of the brain. It is divided into two halves and is made up of various arteries, including the anterior communicating artery, anterior cerebral artery, internal carotid artery, posterior communicating artery, and posterior cerebral arteries. The circle and its branches supply blood to important areas of the brain, such as the corpus striatum, internal capsule, diencephalon, and midbrain.

      The vertebral arteries enter the cranial cavity through the foramen magnum and lie in the subarachnoid space. They then ascend on the anterior surface of the medulla oblongata and unite to form the basilar artery at the base of the pons. The basilar artery has several branches, including the anterior inferior cerebellar artery, labyrinthine artery, pontine arteries, superior cerebellar artery, and posterior cerebral artery.

      The internal carotid arteries also have several branches, such as the posterior communicating artery, anterior cerebral artery, middle cerebral artery, and anterior choroid artery. These arteries supply blood to different parts of the brain, including the frontal, temporal, and parietal lobes. Overall, the Circle of Willis and its branches play a crucial role in providing oxygen and nutrients to the brain.

    • This question is part of the following fields:

      • Cardiovascular System
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  • Question 14 - A 26-year-old Afro-Caribbean woman comes to the Emergency Department complaining of dyspnoea and...

    Incorrect

    • A 26-year-old Afro-Caribbean woman comes to the Emergency Department complaining of dyspnoea and fatigue that has been going on for 2 days. She reports experiencing similar episodes repeatedly over the past few years. She has no other medical history.

      During the examination, you observe sporadic erythematous lesions on her shins and detect a pansystolic murmur. You request a chest x-ray, which reveals bilateral hilar lymphadenopathy and an enlarged heart.

      What additional symptom is linked to this ailment?

      Your Answer:

      Correct Answer: Reduced ventricular ejection fraction

      Explanation:

      Patients with reduced ejection fraction heart failure (HF-rEF) usually experience systolic dysfunction, which refers to the impaired ability of the myocardium to contract during systole.

      Types of Heart Failure

      Heart failure is a clinical syndrome where the heart cannot pump enough blood to meet the body’s metabolic needs. It can be classified in multiple ways, including by ejection fraction, time, and left/right side. Patients with heart failure may have a normal or abnormal left ventricular ejection fraction (LVEF), which is measured using echocardiography. Reduced LVEF is typically defined as < 35 to 40% and is termed heart failure with reduced ejection fraction (HF-rEF), while preserved LVEF is termed heart failure with preserved ejection fraction (HF-pEF). Heart failure can also be described as acute or chronic, with acute heart failure referring to an acute exacerbation of chronic heart failure. Left-sided heart failure is more common and may be due to increased left ventricular afterload or preload, while right-sided heart failure is caused by increased right ventricular afterload or preload. High-output heart failure is another type of heart failure that occurs when a normal heart is unable to pump enough blood to meet the body's metabolic needs. By classifying heart failure in these ways, healthcare professionals can better understand the underlying causes and tailor treatment plans accordingly. It is important to note that many guidelines for the management of heart failure only cover HF-rEF patients and do not address the management of HF-pEF patients. Understanding the different types of heart failure can help healthcare professionals provide more effective care for their patients.

    • This question is part of the following fields:

      • Cardiovascular System
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  • Question 15 - Ella, a 69-year-old female, arrives at the emergency department with abrupt tearing abdominal...

    Incorrect

    • Ella, a 69-year-old female, arrives at the emergency department with abrupt tearing abdominal pain that radiates to her back.

      Ella has a medical history of hypertension, hypercholesterolemia, and diabetes. Her body mass index is 31 kg/m². She smokes 10 cigarettes a day.

      The emergency physician orders an ECG and MRI, which confirm the diagnosis of an aortic dissection.

      Which layer or layers of the aorta are impacted?

      Your Answer:

      Correct Answer: Tear in tunica intima

      Explanation:

      An aortic dissection occurs when there is a tear in the innermost layer (tunica intima) of the aorta’s wall. This tear allows blood to flow into the space between the tunica intima and the middle layer (tunica media), causing pooling. The tear only affects the tunica intima layer and does not involve the outermost layer (tunica externa) or all three layers of the aortic wall.

      Aortic dissection is a serious condition that can cause chest pain. It occurs when there is a tear in the inner layer of the aorta’s wall. Hypertension is the most significant risk factor, but it can also be associated with trauma, bicuspid aortic valve, and certain genetic disorders. Symptoms of aortic dissection include severe and sharp chest or back pain, weak or absent pulses, hypertension, and aortic regurgitation. Specific arteries’ involvement can cause other symptoms such as angina, paraplegia, or limb ischemia. The Stanford classification divides aortic dissection into type A, which affects the ascending aorta, and type B, which affects the descending aorta. The DeBakey classification further divides type A into type I, which extends to the aortic arch and beyond, and type II, which is confined to the ascending aorta. Type III originates in the descending aorta and rarely extends proximally.

    • This question is part of the following fields:

      • Cardiovascular System
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  • Question 16 - A 6-year-old boy is brought to the paediatrician by his parents due to...

    Incorrect

    • A 6-year-old boy is brought to the paediatrician by his parents due to a fever and sore throat that has been bothering him for the past 24 hours. The boy is experiencing significant discomfort in his throat and has been refusing to eat or drink. He does not report having a cough or a runny nose. The boy was delivered via spontaneous vaginal delivery and has been developing normally. He has two healthy older siblings. During the examination, the doctor observes that the boy's tonsils are inflamed and enlarged, with some white exudates, as well as enlarged cervical lymph nodes. The boy's temperature is 38.2 °C. The doctor informs the parents that the boy requires antibiotics to treat the current infection and prevent the risk of a severe complication commonly associated with this particular infection. What complication can be prevented with prompt antibiotic treatment?

      Your Answer:

      Correct Answer: Acute rheumatic fever

      Explanation:

      Pharyngitis is the likely diagnosis for this patient based on their presenting symptoms. Group A streptococcus, also known as Streptococcus pyogenes, is a common cause of pharyngitis in young patients. One of the most concerning complications of this infection is acute rheumatic fever, which can lead to damage to the heart valves. Early antibiotic treatment can prevent the development of this serious condition.

      1: Septicemia can result from various bacterial infections, but it is not typically associated with Group A streptococcal pharyngitis. Additionally, septicemia is rare in patients with this type of pharyngitis, as the condition usually resolves on its own without treatment.

      2: Acute rheumatic fever is a serious complication of Group A streptococcal pharyngitis. It is an immune system reaction that damages the heart valves, particularly the mitral valve. Mitral valve regurgitation is common in the early stages of the disease, followed by mitral stenosis later on.

      3: Post-streptococcal glomerulonephritis is another possible complication of Group A streptococcal pharyngitis. Unlike acute rheumatic fever, however, prompt antibiotic treatment does not prevent its development.

      4: While Group A streptococcus can cause cellulitis, this is a separate condition from pharyngitis and is not a complication of the same bacterial infection.

      5:

      Rheumatic fever is a condition that occurs as a result of an immune response to a recent Streptococcus pyogenes infection, typically occurring 2-4 weeks after the initial infection. The pathogenesis of rheumatic fever involves the activation of the innate immune system, leading to antigen presentation to T cells. B and T cells then produce IgG and IgM antibodies, and CD4+ T cells are activated. This immune response is thought to be cross-reactive, mediated by molecular mimicry, where antibodies against M protein cross-react with myosin and the smooth muscle of arteries. This response leads to the clinical features of rheumatic fever, including Aschoff bodies, which are granulomatous nodules found in rheumatic heart fever.

      To diagnose rheumatic fever, evidence of recent streptococcal infection must be present, along with 2 major criteria or 1 major criterion and 2 minor criteria. Major criteria include erythema marginatum, Sydenham’s chorea, polyarthritis, carditis and valvulitis, and subcutaneous nodules. Minor criteria include raised ESR or CRP, pyrexia, arthralgia, and prolonged PR interval.

      Management of rheumatic fever involves antibiotics, typically oral penicillin V, as well as anti-inflammatories such as NSAIDs as first-line treatment. Any complications that develop, such as heart failure, should also be treated. It is important to diagnose and treat rheumatic fever promptly to prevent long-term complications such as rheumatic heart disease.

    • This question is part of the following fields:

      • Cardiovascular System
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  • Question 17 - A 55-year-old man with several cardiac risk factors arrives at the hospital with...

    Incorrect

    • A 55-year-old man with several cardiac risk factors arrives at the hospital with sudden onset chest pain in the center. The pain extends to his left arm and is accompanied by sweating and nausea.

      The patient's ECG reveals widespread T-wave inversion, which is a new finding compared to his previous ECGs. The level of troponin I in his serum is measured and confirmed to be elevated. The patient is initiated on treatment for acute coronary syndrome and transferred to a cardiac center.

      What is the target of this measured cardiac biomarker?

      Your Answer:

      Correct Answer: Actin

      Explanation:

      Troponin I is a cardiac biomarker that binds to actin, which holds the troponin-tropomyosin complex in place and regulates muscle contraction. It is the standard biomarker used in conjunction with ECGs and clinical findings to diagnose non-ST elevation myocardial infarction (NSTEMI). Troponin I is highly sensitive and specific for myocardial damage compared to other cardiac biomarkers. Troponin C, another subunit of troponin, plays a role in Ca2+-dependent regulation of muscle contraction and can also be used in the diagnosis of myocardial infarction, but it is less specific as it is found in both cardiac and skeletal muscle. Copeptin, an amino acid peptide, is released earlier than troponin during acute myocardial infarction but is not widely used in clinical practice and has no interaction with troponin. Myoglobin, an iron- and oxygen-binding protein found in both cardiac and skeletal muscle, has poor specificity for cardiac injury and is not involved in the troponin-tropomyosin complex.

      Understanding Troponin: The Proteins Involved in Muscle Contraction

      Troponin is a group of three proteins that play a crucial role in the contraction of skeletal and cardiac muscles. These proteins work together to regulate the interaction between actin and myosin, which is essential for muscle contraction. The three subunits of troponin are troponin C, troponin T, and troponin I.

      Troponin C is responsible for binding to calcium ions, which triggers the contraction of muscle fibers. Troponin T binds to tropomyosin, forming a complex that helps regulate the interaction between actin and myosin. Finally, troponin I binds to actin, holding the troponin-tropomyosin complex in place and preventing muscle contraction when it is not needed.

      Understanding the role of troponin is essential for understanding how muscles work and how they can be affected by various diseases and conditions. By regulating the interaction between actin and myosin, troponin plays a critical role in muscle contraction and is a key target for drugs used to treat conditions such as heart failure and skeletal muscle disorders.

    • This question is part of the following fields:

      • Cardiovascular System
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  • Question 18 - Which of the following is not a hepatic artery branch? ...

    Incorrect

    • Which of the following is not a hepatic artery branch?

      Your Answer:

      Correct Answer: Pancreatic artery

      Explanation:

      The Coeliac Axis and its Branches

      The coeliac axis is a major artery that supplies blood to the upper abdominal organs. It has three main branches: the left gastric, hepatic, and splenic arteries. The hepatic artery further branches into the right gastric, gastroduodenal, right gastroepiploic, superior pancreaticoduodenal, and cystic arteries. Meanwhile, the splenic artery gives off the pancreatic, short gastric, and left gastroepiploic arteries. Occasionally, the coeliac axis also gives off one of the inferior phrenic arteries.

      The coeliac axis is located anteriorly to the lesser omentum and is related to the right and left coeliac ganglia, as well as the caudate process of the liver and the gastric cardia. Inferiorly, it is in close proximity to the upper border of the pancreas and the renal vein.

      Understanding the anatomy and branches of the coeliac axis is important in diagnosing and treating conditions that affect the upper abdominal organs, such as pancreatic cancer or gastric ulcers.

    • This question is part of the following fields:

      • Cardiovascular System
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  • Question 19 - Which nerve is most vulnerable to damage when there is a cut on...

    Incorrect

    • Which nerve is most vulnerable to damage when there is a cut on the upper lateral margin of the popliteal fossa in older adults?

      Your Answer:

      Correct Answer: Common peroneal nerve

      Explanation:

      The lower infero-lateral aspect of the fossa is where the sural nerve exits, and it is at a higher risk during short saphenous vein surgery. On the other hand, the tibial nerve is located more medially and is less susceptible to injury in this area.

      Anatomy of the Popliteal Fossa

      The popliteal fossa is a diamond-shaped space located at the back of the knee joint. It is bound by various muscles and ligaments, including the biceps femoris, semimembranosus, semitendinosus, and gastrocnemius. The floor of the popliteal fossa is formed by the popliteal surface of the femur, posterior ligament of the knee joint, and popliteus muscle, while the roof is made up of superficial and deep fascia.

      The popliteal fossa contains several important structures, including the popliteal artery and vein, small saphenous vein, common peroneal nerve, tibial nerve, posterior cutaneous nerve of the thigh, genicular branch of the obturator nerve, and lymph nodes. These structures are crucial for the proper functioning of the lower leg and foot.

      Understanding the anatomy of the popliteal fossa is important for healthcare professionals, as it can help in the diagnosis and treatment of various conditions affecting the knee joint and surrounding structures.

    • This question is part of the following fields:

      • Cardiovascular System
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  • Question 20 - A 55-year-old woman with resistant hypertension is currently on ramipril and amlodipine. The...

    Incorrect

    • A 55-year-old woman with resistant hypertension is currently on ramipril and amlodipine. The GP wants to add a diuretic that primarily acts on the distal convoluted tubule. What diuretic should be considered?

      Your Answer:

      Correct Answer: Bendroflumethiazide (thiazide diuretic)

      Explanation:

      Thiazide diuretics are medications that work by blocking the thiazide-sensitive Na+-Cl− symporter, which inhibits sodium reabsorption at the beginning of the distal convoluted tubule (DCT). This results in the loss of potassium as more sodium reaches the collecting ducts. While thiazide diuretics are useful in treating mild heart failure, loop diuretics are more effective in reducing overload. Bendroflumethiazide was previously used to manage hypertension, but recent NICE guidelines recommend other thiazide-like diuretics such as indapamide and chlorthalidone.

      Common side effects of thiazide diuretics include dehydration, postural hypotension, and electrolyte imbalances such as hyponatremia, hypokalemia, and hypercalcemia. Other potential adverse effects include gout, impaired glucose tolerance, and impotence. Rare side effects may include thrombocytopenia, agranulocytosis, photosensitivity rash, and pancreatitis.

      It is worth noting that while thiazide diuretics may cause hypercalcemia, they can also reduce the incidence of renal stones by decreasing urinary calcium excretion. According to current NICE guidelines, the management of hypertension involves the use of thiazide-like diuretics, along with other medications and lifestyle changes, to achieve optimal blood pressure control and reduce the risk of cardiovascular disease.

    • This question is part of the following fields:

      • Cardiovascular System
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  • Question 21 - A 75-year-old collapses at home and is rushed to the Emergency Room but...

    Incorrect

    • A 75-year-old collapses at home and is rushed to the Emergency Room but dies despite resuscitation efforts. He had a myocardial infarction five weeks prior. What histological findings would be expected in his heart?

      Your Answer:

      Correct Answer: Contracted scar

      Explanation:

      The histology findings of a myocardial infarction (MI) vary depending on the time elapsed since the event. Within the first 24 hours, early coagulative necrosis, neutrophils, wavy fibres, and hypercontraction of myofibrils are observed, which increase the risk of ventricular arrhythmia, heart failure, and cardiogenic shock. Between 1-3 days post-MI, extensive coagulative necrosis and neutrophils are present, which can lead to fibrinous pericarditis. From 3-14 days post-MI, macrophages and granulation tissue are seen at the margins, and there is a high risk of complications such as free wall rupture (resulting in mitral regurgitation), papillary muscle rupture, and left ventricular pseudoaneurysm. Finally, from 2 weeks to several months post-MI, a contracted scar is formed, which is associated with Dressler syndrome, heart failure, arrhythmias, and mural thrombus.

      Myocardial infarction (MI) can lead to various complications, which can occur immediately, early, or late after the event. Cardiac arrest is the most common cause of death following MI, usually due to ventricular fibrillation. Cardiogenic shock may occur if a large part of the ventricular myocardium is damaged, and it is difficult to treat. Chronic heart failure may result from ventricular myocardium dysfunction, which can be managed with loop diuretics, ACE-inhibitors, and beta-blockers. Tachyarrhythmias, such as ventricular fibrillation and ventricular tachycardia, are common complications. Bradyarrhythmias, such as atrioventricular block, are more common following inferior MI. Pericarditis is common in the first 48 hours after a transmural MI, while Dressler’s syndrome may occur 2-6 weeks later. Left ventricular aneurysm and free wall rupture, ventricular septal defect, and acute mitral regurgitation are other complications that may require urgent medical attention.

    • This question is part of the following fields:

      • Cardiovascular System
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  • Question 22 - A 65-year-old man with a history of angina, hypertension, and hypercholesterolaemia has been...

    Incorrect

    • A 65-year-old man with a history of angina, hypertension, and hypercholesterolaemia has been discharged from the hospital after experiencing a non-ST-elevation myocardial infarction (NSTEMI). He was already taking aspirin, atorvastatin, bisoprolol, and ramipril before his NSTEMI. As part of his post-discharge instructions, he has been advised to take ticagrelor for the next 12 months. What is the mechanism of action of this newly prescribed medication?

      Your Answer:

      Correct Answer: P2Y12 receptor antagonist

      Explanation:

      Ticagrelor functions similarly to clopidogrel by hindering the binding of ADP to platelet receptors. It is prescribed to prevent atherothrombotic events in individuals with acute coronary syndrome (ACS) and is typically administered in conjunction with aspirin. Additionally, it is a specific and reversible inhibitor.

      ADP receptor inhibitors, such as clopidogrel, prasugrel, ticagrelor, and ticlopidine, work by inhibiting the P2Y12 receptor, which leads to sustained platelet aggregation and stabilization of the platelet plaque. Clinical trials have shown that prasugrel and ticagrelor are more effective than clopidogrel in reducing short- and long-term ischemic events in high-risk patients with acute coronary syndrome or undergoing percutaneous coronary intervention. However, ticagrelor may cause dyspnea due to impaired clearance of adenosine, and there are drug interactions and contraindications to consider for each medication. NICE guidelines recommend dual antiplatelet treatment with aspirin and ticagrelor for 12 months as a secondary prevention strategy for ACS.

    • This question is part of the following fields:

      • Cardiovascular System
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  • Question 23 - A 65-year-old man is admitted after experiencing an acute coronary syndrome. He is...

    Incorrect

    • A 65-year-old man is admitted after experiencing an acute coronary syndrome. He is prescribed aspirin, clopidogrel, nitrates, and morphine. Due to his high 6-month risk score, percutaneous coronary intervention is planned and he is given intravenous tirofiban. What is the mechanism of action of this medication?

      Your Answer:

      Correct Answer: Glycoprotein IIb/IIIa receptor antagonist

      Explanation:

      Glycoprotein IIb/IIIa Receptor Antagonists

      Glycoprotein IIb/IIIa receptor antagonists are a class of drugs that inhibit the function of the glycoprotein IIb/IIIa receptor, which is found on the surface of platelets. These drugs are used to prevent blood clots from forming in patients with acute coronary syndrome, unstable angina, or during percutaneous coronary intervention (PCI).

      Examples of glycoprotein IIb/IIIa receptor antagonists include abciximab, eptifibatide, and tirofiban. These drugs work by blocking the binding of fibrinogen to the glycoprotein IIb/IIIa receptor, which prevents platelet aggregation and the formation of blood clots.

      Glycoprotein IIb/IIIa receptor antagonists are typically administered intravenously and are used in combination with other antiplatelet agents, such as aspirin and clopidogrel. While these drugs are effective at preventing blood clots, they can also increase the risk of bleeding. Therefore, careful monitoring of patients is necessary to ensure that the benefits of these drugs outweigh the risks.

    • This question is part of the following fields:

      • Cardiovascular System
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  • Question 24 - A woman is expecting a baby with Down's syndrome. At the routine 22-week...

    Incorrect

    • A woman is expecting a baby with Down's syndrome. At the routine 22-week scan, a congenital anomaly was detected. The doctor explained to her and her partner that the defect resolves spontaneously in approximately 50% of cases but can present with a pansystolic murmur after birth. What is the probable congenital defect being described?

      Your Answer:

      Correct Answer: Ventricular septal defect

      Explanation:

      Understanding Ventricular Septal Defect

      Ventricular septal defect (VSD) is a common congenital heart disease that affects many individuals. It is caused by a hole in the wall that separates the two lower chambers of the heart. In some cases, VSDs may close on their own, but in other cases, they require specialized management.

      There are various causes of VSDs, including chromosomal disorders such as Down’s syndrome, Edward’s syndrome, Patau syndrome, and cri-du-chat syndrome. Congenital infections and post-myocardial infarction can also lead to VSDs. The condition can be detected during routine scans in utero or may present post-natally with symptoms such as failure to thrive, heart failure, hepatomegaly, tachypnea, tachycardia, pallor, and a pansystolic murmur.

      Management of VSDs depends on the size and symptoms of the defect. Small VSDs that are asymptomatic may require monitoring, while moderate to large VSDs may result in heart failure and require nutritional support, medication for heart failure, and surgical closure of the defect.

      Complications of VSDs include aortic regurgitation, infective endocarditis, Eisenmenger’s complex, right heart failure, and pulmonary hypertension. Eisenmenger’s complex is a severe complication that results in cyanosis and clubbing and is an indication for a heart-lung transplant. Women with pulmonary hypertension are advised against pregnancy as it carries a high risk of mortality.

      In conclusion, VSD is a common congenital heart disease that requires specialized management. Early detection and appropriate treatment can prevent severe complications and improve outcomes for affected individuals.

    • This question is part of the following fields:

      • Cardiovascular System
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  • Question 25 - A 12-year-old child presents to the emergency department with polyarthritis and chest pain...

    Incorrect

    • A 12-year-old child presents to the emergency department with polyarthritis and chest pain that is relieved by leaning forward. Blood tests reveal a raised ESR and leucocytosis, but are otherwise normal. The child's parents mention that they have never vaccinated their child as they themselves are unvaccinated and rarely fall ill. In light of this information, you decide to order an anti-streptolysin-O-titre to investigate for recent streptococcal infection. What is the immunological term used to describe the mechanism behind the development of this condition?

      Your Answer:

      Correct Answer: Molecular mimicry

      Explanation:

      Rheumatic fever is caused by molecular mimicry, where the M protein on the cell wall of Streptococcus pyogenes cross-reacts with myosin in the smooth muscles of arteries, leading to autoimmunity. This is evidenced by the patient’s symptoms of polyarthritis and chest pain, as well as the presence of anti-streptolysin-O-titre in their blood. Bystander activation, exposure to cryptic antigens, and super-antigens are all pathophysiological mechanisms that can lead to autoimmune destruction of tissues.

      Rheumatic fever is a condition that occurs as a result of an immune response to a recent Streptococcus pyogenes infection, typically occurring 2-4 weeks after the initial infection. The pathogenesis of rheumatic fever involves the activation of the innate immune system, leading to antigen presentation to T cells. B and T cells then produce IgG and IgM antibodies, and CD4+ T cells are activated. This immune response is thought to be cross-reactive, mediated by molecular mimicry, where antibodies against M protein cross-react with myosin and the smooth muscle of arteries. This response leads to the clinical features of rheumatic fever, including Aschoff bodies, which are granulomatous nodules found in rheumatic heart fever.

      To diagnose rheumatic fever, evidence of recent streptococcal infection must be present, along with 2 major criteria or 1 major criterion and 2 minor criteria. Major criteria include erythema marginatum, Sydenham’s chorea, polyarthritis, carditis and valvulitis, and subcutaneous nodules. Minor criteria include raised ESR or CRP, pyrexia, arthralgia, and prolonged PR interval.

      Management of rheumatic fever involves antibiotics, typically oral penicillin V, as well as anti-inflammatories such as NSAIDs as first-line treatment. Any complications that develop, such as heart failure, should also be treated. It is important to diagnose and treat rheumatic fever promptly to prevent long-term complications such as rheumatic heart disease.

    • This question is part of the following fields:

      • Cardiovascular System
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  • Question 26 - A baby is born prematurely at 28 weeks, increasing the likelihood of delayed...

    Incorrect

    • A baby is born prematurely at 28 weeks, increasing the likelihood of delayed closure of the ductus venosus. What are the structures that the ductus venosus connects in the fetus?

      Your Answer:

      Correct Answer: IVC and umbilical vein

      Explanation:

      During fetal development, the ductus venosus redirects blood flow from the left umbilical vein directly to the inferior vena cava, enabling oxygenated blood from the placenta to bypass the fetal liver. Typically, the ductus closes and becomes the ligamentum venosum between day 3 and 7. However, premature infants are more susceptible to delayed closure.

      During cardiovascular embryology, the heart undergoes significant development and differentiation. At around 14 days gestation, the heart consists of primitive structures such as the truncus arteriosus, bulbus cordis, primitive atria, and primitive ventricle. These structures give rise to various parts of the heart, including the ascending aorta and pulmonary trunk, right ventricle, left and right atria, and majority of the left ventricle. The division of the truncus arteriosus is triggered by neural crest cell migration from the pharyngeal arches, and any issues with this migration can lead to congenital heart defects such as transposition of the great arteries or tetralogy of Fallot. Other structures derived from the primitive heart include the coronary sinus, superior vena cava, fossa ovalis, and various ligaments such as the ligamentum arteriosum and ligamentum venosum. The allantois gives rise to the urachus, while the umbilical artery becomes the medial umbilical ligaments and the umbilical vein becomes the ligamentum teres hepatis inside the falciform ligament. Overall, cardiovascular embryology is a complex process that involves the differentiation and development of various structures that ultimately form the mature heart.

    • This question is part of the following fields:

      • Cardiovascular System
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  • Question 27 - A 50-year-old man comes to the clinic complaining of a painful left foot...

    Incorrect

    • A 50-year-old man comes to the clinic complaining of a painful left foot that he woke up with. Initially, he didn't want to bother the doctor, but now he's concerned because he can't feel his foot or move his toes. Upon examination, the left foot is cold to the touch and very pale. What is the probable diagnosis?

      Your Answer:

      Correct Answer: Acute limb ischaemia

      Explanation:

      Acute Limb Ischaemia and Compartment Syndrome

      Acute limb ischaemia is a condition that is characterized by six Ps: pain, pallor, pulselessness, perishingly cold, paresthesia, and paralysis. It is a medical emergency that requires immediate attention from a vascular surgeon. Delaying treatment for even a few hours can lead to amputation or death. On the other hand, acute compartment syndrome occurs when the pressure within a closed muscle compartment exceeds the perfusion pressure, resulting in muscle and nerve ischaemia. This condition usually follows a traumatic event, such as a fracture. However, in some cases, there may be no history of trauma.

    • This question is part of the following fields:

      • Cardiovascular System
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  • Question 28 - An 80-year-old man arrives at the emergency department complaining of chest pain, sweating,...

    Incorrect

    • An 80-year-old man arrives at the emergency department complaining of chest pain, sweating, and nausea. His ECG reveals ST elevation. Which phase of the cardiac action potential does this correspond to? The ST segment of the ECG represents a period of sluggish calcium influx in the cardiac action potential.

      Your Answer:

      Correct Answer: Phase 2

      Explanation:

      The ST segment in the ECG is caused by the slow influx of calcium during phase 2 of the cardiac action potential. Understanding the cardiac action potential is important for interpreting the electrical activity of the heart as reflected in the ECG waveform. The QRS complex represents rapid depolarisation, the ST segment represents the plateau phase, and the T wave represents repolarisation.

      Understanding the Cardiac Action Potential and Conduction Velocity

      The cardiac action potential is a series of electrical events that occur in the heart during each heartbeat. It is responsible for the contraction of the heart muscle and the pumping of blood throughout the body. The action potential is divided into five phases, each with a specific mechanism. The first phase is rapid depolarization, which is caused by the influx of sodium ions. The second phase is early repolarization, which is caused by the efflux of potassium ions. The third phase is the plateau phase, which is caused by the slow influx of calcium ions. The fourth phase is final repolarization, which is caused by the efflux of potassium ions. The final phase is the restoration of ionic concentrations, which is achieved by the Na+/K+ ATPase pump.

      Conduction velocity is the speed at which the electrical signal travels through the heart. The speed varies depending on the location of the signal. Atrial conduction spreads along ordinary atrial myocardial fibers at a speed of 1 m/sec. AV node conduction is much slower, at 0.05 m/sec. Ventricular conduction is the fastest in the heart, achieved by the large diameter of the Purkinje fibers, which can achieve velocities of 2-4 m/sec. This allows for a rapid and coordinated contraction of the ventricles, which is essential for the proper functioning of the heart. Understanding the cardiac action potential and conduction velocity is crucial for diagnosing and treating heart conditions.

    • This question is part of the following fields:

      • Cardiovascular System
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  • Question 29 - During a tricuspid valve repair, the right atrium is opened after establishing cardiopulmonary...

    Incorrect

    • During a tricuspid valve repair, the right atrium is opened after establishing cardiopulmonary bypass. Which of the following structures is not located within the right atrium?

      Your Answer:

      Correct Answer: Trabeculae carnae

      Explanation:

      The walls of each cardiac chamber are made up of the epicardium, myocardium, and endocardium. The heart and roots of the great vessels are related anteriorly to the sternum and the left ribs. The coronary sinus receives blood from the cardiac veins, and the aortic sinus gives rise to the right and left coronary arteries. The left ventricle has a thicker wall and more numerous trabeculae carnae than the right ventricle. The heart is innervated by autonomic nerve fibers from the cardiac plexus, and the parasympathetic supply comes from the vagus nerves. The heart has four valves: the mitral, aortic, pulmonary, and tricuspid valves.

    • This question is part of the following fields:

      • Cardiovascular System
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  • Question 30 - A 75-year-old male presents to his GP with a four week history of...

    Incorrect

    • A 75-year-old male presents to his GP with a four week history of shortness of breath when he walks for approximately two minutes on level ground. There is also an associated central chest pain which resolves when he rests. The pain is localised and does not radiate.

      On examination, there were obvious signs of ankle and sacral pitting oedema. A left ventricular heave was palpated but the apex beat was not displaced. A systolic murmur was heard best at the second intercostal space just right of the sternum. This murmur also radiated to the carotid arteries.

      Which investigation is most likely to confirm the underlying cause of his symptoms?

      Your Answer:

      Correct Answer: Echocardiogram

      Explanation:

      Diagnosis of Valvular Heart Disease

      Echocardiography is the most sensitive and specific way to diagnose valvular heart disease (VHD). It involves observing the valvular leaflets and degree of calcified stenosis of the aortic valve, as well as calculating cardiac output and ejection fraction for prognostic information. Chest x-ray may reveal a calcified aortic valve and left ventricular hypertrophy, while bilateral ankle edema is a minor sign for congestive heart failure. To assess the severity of heart failure, an x-ray, ECG, and BNP should be performed, but echocardiogram remains the most reliable diagnostic tool for VHD.

      A myocardial infarction is unlikely in this patient due to her age and the duration of symptoms. Instead, her angina-type pain is likely due to her underlying aortic valve disease. An angiogram of the coronary arteries alone cannot diagnose valvular defects. Cardiac enzymes such as troponin I and T are markers for myocardial necrosis and will not aid in the diagnosis of VHD. While ECG should be performed in a patient presenting with these symptoms, it alone is insufficient to diagnose VHD. The ECG may show left axis deviation due to left ventricular hypertrophy.

    • This question is part of the following fields:

      • Cardiovascular System
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