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Question 1
Correct
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A toddler is brought to the hospital at 18 months of age with symptoms of increased work of breathing and difficulty while feeding. On examination, a continuous 'machinery' murmur is heard and is loudest at the left sternal edge. The cardiologist prescribes a dose of indomethacin. What is the mechanism of action of indomethacin?
The baby was born prematurely at 36 weeks via an emergency cesarean section. Despite the early delivery, the baby appeared healthy and was given a dose of Vitamin K soon after birth. The mother lived in a cottage up in the mountains and was discharged the next day with her happy, healthy baby. However, six weeks later, the baby was brought back to the hospital with concerning symptoms.Your Answer: Prostaglandin synthase inhibitor
Explanation:Indomethacin is a medication that hinders the production of prostaglandins in infants with patent ductus arteriosus by inhibiting the activity of COX enzymes. On the other hand, bosentan, an endothelin receptor antagonist, is utilized to treat pulmonary hypertension by blocking the vasoconstricting effect of endothelin, leading to vasodilation. Although endothelin causes vasoconstriction by acting on endothelin receptors, it is not employed in managing PDA. Adenosine receptor antagonists like theophylline and caffeine are also not utilized in PDA management.
Understanding Patent Ductus Arteriosus
Patent ductus arteriosus is a type of congenital heart defect that is generally classified as ‘acyanotic’. However, if left uncorrected, it can eventually result in late cyanosis in the lower extremities, which is termed differential cyanosis. This condition is caused by a connection between the pulmonary trunk and descending aorta. Normally, the ductus arteriosus closes with the first breaths due to increased pulmonary flow, which enhances prostaglandins clearance. However, in some cases, this connection remains open, leading to patent ductus arteriosus.
This condition is more common in premature babies, those born at high altitude, or those whose mothers had rubella infection in the first trimester. The features of patent ductus arteriosus include a left subclavicular thrill, continuous ‘machinery’ murmur, large volume, bounding, collapsing pulse, wide pulse pressure, and heaving apex beat.
The management of patent ductus arteriosus involves the use of indomethacin or ibuprofen, which are given to the neonate. These medications inhibit prostaglandin synthesis and close the connection in the majority of cases. If patent ductus arteriosus is associated with another congenital heart defect amenable to surgery, then prostaglandin E1 is useful to keep the duct open until after surgical repair. Understanding patent ductus arteriosus is important for early diagnosis and management of this condition.
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This question is part of the following fields:
- Cardiovascular System
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Question 2
Incorrect
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A 47-year-old woman has a laparoscopic cholecystectomy as a day case procedure. The surgery proves to be more challenging than expected, and a drain is inserted at the surgical site. During recovery, the patient experiences a significant loss of 1800ml of visible blood into the drain. Which of the following outcomes is not expected?
Your Answer: Increase in sympathetic discharge to ventricular muscle
Correct Answer: Release of aldosterone via the Bainbridge reflex
Explanation:The Bainbridge reflex is a response where the heart rate is elevated due to the activation of atrial stretch receptors following a sudden infusion of blood.
The heart has four chambers and generates pressures of 0-25 mmHg on the right side and 0-120 mmHg on the left. The cardiac output is the product of heart rate and stroke volume, typically 5-6L per minute. The cardiac impulse is generated in the sino atrial node and conveyed to the ventricles via the atrioventricular node. Parasympathetic and sympathetic fibers project to the heart via the vagus and release acetylcholine and noradrenaline, respectively. The cardiac cycle includes mid diastole, late diastole, early systole, late systole, and early diastole. Preload is the end diastolic volume and afterload is the aortic pressure. Laplace’s law explains the rise in ventricular pressure during the ejection phase and why a dilated diseased heart will have impaired systolic function. Starling’s law states that an increase in end-diastolic volume will produce a larger stroke volume up to a point beyond which stroke volume will fall. Baroreceptor reflexes and atrial stretch receptors are involved in regulating cardiac output.
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This question is part of the following fields:
- Cardiovascular System
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Question 3
Correct
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Where is troponin T located within the body?
Your Answer: Heart
Explanation:Troponin and Its Significance in Cardiac Health
Troponin is an enzyme that is specific to the heart and is used to detect injury to the heart muscle. It is commonly measured in patients who present with chest pain that may be related to heart problems. Elevated levels of troponin can indicate a heart attack or other acute coronary syndromes. However, it is important to note that troponin levels may also be slightly elevated in other conditions such as renal failure, cardiomyopathy, myocarditis, and large pulmonary embolism.
Troponin is a crucial marker in the diagnosis and management of cardiac conditions. It is a reliable indicator of heart muscle damage and can help healthcare professionals determine the best course of treatment for their patients. Additionally, troponin levels can provide prognostic information, allowing doctors to predict the likelihood of future cardiac events. It is important for individuals to understand the significance of troponin in their cardiac health and to seek medical attention if they experience any symptoms of heart problems.
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This question is part of the following fields:
- Cardiovascular System
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Question 4
Incorrect
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A 36-year-old woman is scheduled for a parathyroidectomy to treat her hyperparathyroidism. During the surgery, an enlarged inferior parathyroid gland is identified with a vessel located adjacent to it laterally. Which vessel is most likely to be in this location?
Your Answer: External carotid artery
Correct Answer: Common carotid artery
Explanation:The inferior parathyroid is located laterally to the common carotid artery.
Anatomy and Development of the Parathyroid Glands
The parathyroid glands are four small glands located posterior to the thyroid gland within the pretracheal fascia. They develop from the third and fourth pharyngeal pouches, with those derived from the fourth pouch located more superiorly and associated with the thyroid gland, while those from the third pouch lie more inferiorly and may become associated with the thymus.
The blood supply to the parathyroid glands is derived from the inferior and superior thyroid arteries, with a rich anastomosis between the two vessels. Venous drainage is into the thyroid veins. The parathyroid glands are surrounded by various structures, with the common carotid laterally, the recurrent laryngeal nerve and trachea medially, and the thyroid anteriorly. Understanding the anatomy and development of the parathyroid glands is important for their proper identification and preservation during surgical procedures.
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This question is part of the following fields:
- Cardiovascular System
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Question 5
Correct
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An 80-year-old man presents to the emergency department with complaints of chest pain, dizziness, and palpitations. He has a medical history of mitral stenosis and denies any alcohol or smoking habits. Upon conducting an ECG, it is observed that lead I shows positively directed sawtooth deflections, while leads II, III, and aVF show negatively directed sawtooth deflections. What pathology does this finding suggest?
Your Answer: Atrial flutter
Explanation:Atrial flutter is identified by a sawtooth pattern on the ECG and is a type of supraventricular tachycardia. It occurs when electrical activity from the sinoatrial node reenters the atria instead of being conducted to the ventricles. Valvular heart disease is a risk factor, and atrial flutter is managed similarly to atrial fibrillation.
Left bundle branch block causes a delayed contraction of the left ventricle and is identified by a W pattern in V1 and an M pattern in V6 on an ECG. It does not produce a sawtooth pattern on the ECG.
Ventricular fibrillation is characterized by chaotic electrical conduction in the ventricles, resulting in a lack of normal ventricular contraction. It can cause cardiac arrest and requires advanced life support management.
Wolff-Parkinson-White syndrome is caused by an accessory pathway between the atria and the ventricles and is identified by a slurred upstroke at the beginning of the QRS complex, known as a delta wave. It can present with symptoms such as palpitations, shortness of breath, and syncope.
Atrial flutter is a type of supraventricular tachycardia that is characterized by a series of rapid atrial depolarization waves. This condition can be identified through ECG findings, which show a sawtooth appearance. The underlying atrial rate is typically around 300 beats per minute, which can affect the ventricular or heart rate depending on the degree of AV block. For instance, if there is a 2:1 block, the ventricular rate will be 150 beats per minute. Flutter waves may also be visible following carotid sinus massage or adenosine.
Managing atrial flutter is similar to managing atrial fibrillation, although medication may be less effective. However, atrial flutter is more sensitive to cardioversion, so lower energy levels may be used. For most patients, radiofrequency ablation of the tricuspid valve isthmus is curative.
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This question is part of the following fields:
- Cardiovascular System
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Question 6
Correct
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During surgery on her neck, a woman in her 50s suffers a vagus nerve injury where the nerve is cut near the exit from the skull. She wakes up with a high heart rate and high blood pressure due to loss of parasympathetic tone.
What other features would be expected with a vagus nerve injury?Your Answer: Hoarse voice
Explanation:The vagus (X) nerve is responsible for all innervation related to speech, meaning that any injuries to this nerve can lead to speech problems. It’s important to note that the vagus nerve has both autonomic and somatic effects, with the latter being the most crucial for speech. This involves the motor supply to the larynx through the recurrent laryngeal nerves, which are branches of the vagus. If one vagus nerve is damaged, it would have the same impact as damage to a single recurrent laryngeal nerve, resulting in a hoarse voice.
However, it’s worth noting that anal tone, erections, and urination are controlled by the sacral parasympathetics and would not be affected by the loss of the vagus nerve. Similarly, pupillary constriction is controlled by parasympathetics on the oculomotor nerve and would not be impacted by the loss of the vagus nerve.
The vagus nerve is responsible for a variety of functions and supplies structures from the fourth and sixth pharyngeal arches, as well as the fore and midgut sections of the embryonic gut tube. It carries afferent fibers from areas such as the pharynx, larynx, esophagus, stomach, lungs, heart, and great vessels. The efferent fibers of the vagus are of two main types: preganglionic parasympathetic fibers distributed to the parasympathetic ganglia that innervate smooth muscle of the innervated organs, and efferent fibers with direct skeletal muscle innervation, largely to the muscles of the larynx and pharynx.
The vagus nerve arises from the lateral surface of the medulla oblongata and exits through the jugular foramen, closely related to the glossopharyngeal nerve cranially and the accessory nerve caudally. It descends vertically in the carotid sheath in the neck, closely related to the internal and common carotid arteries. In the mediastinum, both nerves pass posteroinferiorly and reach the posterior surface of the corresponding lung root, branching into both lungs. At the inferior end of the mediastinum, these plexuses reunite to form the formal vagal trunks that pass through the esophageal hiatus and into the abdomen. The anterior and posterior vagal trunks are formal nerve fibers that splay out once again, sending fibers over the stomach and posteriorly to the coeliac plexus. Branches pass to the liver, spleen, and kidney.
The vagus nerve has various branches in the neck, including superior and inferior cervical cardiac branches, and the right recurrent laryngeal nerve, which arises from the vagus anterior to the first part of the subclavian artery and hooks under it to insert into the larynx. In the thorax, the left recurrent laryngeal nerve arises from the vagus on the aortic arch and hooks around the inferior surface of the arch, passing upwards through the superior mediastinum and lower part of the neck. In the abdomen, the nerves branch extensively, passing to the coeliac axis and alongside the vessels to supply the spleen, liver, and kidney.
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This question is part of the following fields:
- Cardiovascular System
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Question 7
Incorrect
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A patient with a history of peripheral vascular disease visits their GP with essential hypertension. Which of the following medications could worsen their peripheral vascular symptoms?
Your Answer: Ramipril
Correct Answer: Atenolol
Explanation:Patients with peripheral vascular disease may experience worsened symptoms when taking beta-blockers, and caution should be exercised when prescribing this medication. Additionally, those with Raynaud disease may also experience aggravated symptoms. Monitoring for signs of progressive arterial obstruction is recommended.
Beta-blockers are a class of drugs that are primarily used to manage cardiovascular disorders. They have a wide range of indications, including angina, post-myocardial infarction, heart failure, arrhythmias, hypertension, thyrotoxicosis, migraine prophylaxis, and anxiety. Beta-blockers were previously avoided in heart failure, but recent evidence suggests that certain beta-blockers can improve both symptoms and mortality. They have also replaced digoxin as the rate-control drug of choice in atrial fibrillation. However, their role in reducing stroke and myocardial infarction has diminished in recent years due to a lack of evidence.
Examples of beta-blockers include atenolol and propranolol, which was one of the first beta-blockers to be developed. Propranolol is lipid-soluble, which means it can cross the blood-brain barrier.
Like all drugs, beta-blockers have side-effects. These can include bronchospasm, cold peripheries, fatigue, sleep disturbances (including nightmares), and erectile dysfunction. There are also some contraindications to using beta-blockers, such as uncontrolled heart failure, asthma, sick sinus syndrome, and concurrent use with verapamil, which can precipitate severe bradycardia.
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This question is part of the following fields:
- Cardiovascular System
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Question 8
Incorrect
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A 50-year-old UK born patient with end-stage kidney failure arrives at the emergency department complaining of sharp chest pain that subsides when sitting forward. The patient has not undergone dialysis yet. Upon conducting an ECG, it is observed that there is a widespread 'saddle-shaped' ST elevation and PR depression, leading to a diagnosis of pericarditis. What could be the probable cause of this pericarditis?
Your Answer: Tuberculosis
Correct Answer: Uraemia
Explanation:There is no indication of trauma in patients with advanced renal failure prior to dialysis initiation.
ECG results do not indicate a recent heart attack.
The patient’s age decreases the likelihood of malignancy.
Acute Pericarditis: Causes, Features, Investigations, and Management
Acute pericarditis is a possible diagnosis for patients presenting with chest pain. The condition is characterized by chest pain, which may be pleuritic and relieved by sitting forwards. Other symptoms include non-productive cough, dyspnoea, and flu-like symptoms. Tachypnoea and tachycardia may also be present, along with a pericardial rub.
The causes of acute pericarditis include viral infections, tuberculosis, uraemia, trauma, post-myocardial infarction, Dressler’s syndrome, connective tissue disease, hypothyroidism, and malignancy.
Investigations for acute pericarditis include ECG changes, which are often global/widespread, as opposed to the ‘territories’ seen in ischaemic events. The ECG may show ‘saddle-shaped’ ST elevation and PR depression, which is the most specific ECG marker for pericarditis. All patients with suspected acute pericarditis should have transthoracic echocardiography.
Management of acute pericarditis involves treating the underlying cause. A combination of NSAIDs and colchicine is now generally used as first-line treatment for patients with acute idiopathic or viral pericarditis.
In summary, acute pericarditis is a possible diagnosis for patients presenting with chest pain. The condition is characterized by chest pain, which may be pleuritic and relieved by sitting forwards, along with other symptoms. The causes of acute pericarditis are varied, and investigations include ECG changes and transthoracic echocardiography. Management involves treating the underlying cause and using a combination of NSAIDs and colchicine as first-line treatment.
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This question is part of the following fields:
- Cardiovascular System
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Question 9
Incorrect
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A fifth-year medical student is requested to perform an abdominal examination on a 58-year-old man who was admitted to the hospital with diffuse abdominal discomfort. The patient has a medical history of chronic obstructive pulmonary disease. The student noted diffuse tenderness in the abdomen without any signs of peritonism, masses, or organ enlargement. The student observed that the liver was bouncing up and down intermittently on the tips of her fingers.
What could be the probable reason for this observation?Your Answer: Hepatitis B
Correct Answer: Tricuspid regurgitation
Explanation:Tricuspid regurgitation causes pulsatile hepatomegaly due to backflow of blood into the liver during the cardiac cycle. Other conditions such as hepatitis, mitral stenosis or mitral regurgitation do not cause this symptom.
Tricuspid Regurgitation: Causes and Signs
Tricuspid regurgitation is a heart condition characterized by the backflow of blood from the right ventricle to the right atrium due to the incomplete closure of the tricuspid valve. This condition can be identified through various signs, including a pansystolic murmur, prominent or giant V waves in the jugular venous pulse, pulsatile hepatomegaly, and a left parasternal heave.
There are several causes of tricuspid regurgitation, including right ventricular infarction, pulmonary hypertension (such as in cases of COPD), rheumatic heart disease, infective endocarditis (especially in intravenous drug users), Ebstein’s anomaly, and carcinoid syndrome. It is important to identify the underlying cause of tricuspid regurgitation in order to determine the appropriate treatment plan.
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This question is part of the following fields:
- Cardiovascular System
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Question 10
Incorrect
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Sarah, a 73-year-old woman, is currently admitted to the medical ward after experiencing chest pain. A recent blood test revealed low levels of potassium. The doctors explained that potassium plays a crucial role in the normal functioning of the heart and any changes in its concentration can affect the heart's ability to contract and relax properly.
How does potassium contribute to a normal cardiac action potential?Your Answer: An efflux of the electrolyte repolarises the cardiomyocytes
Correct Answer: A slow influx of the electrolyte causes a plateau in the myocardial action potential
Explanation:Calcium causes a plateau in the cardiac action potential, prolonging contraction and reflected in the ST-segment of an ECG. A low concentration of calcium ions can result in a prolonged QT-segment. Sodium ions cause depolarisation, potassium ions cause repolarisation, and their movement maintains the resting potential. Calcium ions also bind to troponin-C to trigger muscle contraction.
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.
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This question is part of the following fields:
- Cardiovascular System
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Question 11
Incorrect
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A 72-year-old patient presents to the Emergency Room with central crushing chest pain that radiates to their jaw and left arm. They have a medical history of hypertension, type 2 diabetes mellitus, and hypercholesterolemia. The patient receives percutaneous coronary intervention but unfortunately experiences ventricular fibrillation and passes away 3 days later. What is the probable histological discovery in their heart?
Your Answer: Macrophages and granulation tissue at margins
Correct Answer: Extensive coagulative necrosis, neutrophils
Explanation: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.
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This question is part of the following fields:
- Cardiovascular System
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Question 12
Correct
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A 55-year-old man undergoes a regular health examination, including observation, ECG, and routine blood tests. The ECG reveals an extended corrected QT interval. Which abnormality detected in his blood test could explain the ECG results?
Your Answer: Hypokalaemia
Explanation:Long QT syndrome can be caused by hypokalaemia, among other electrolyte imbalances.
Electrolyte imbalances such as hypocalcaemia and hypomagnesaemia can also result in long QT syndrome.
However, hyperkalaemia, hypercalcaemia, and hypermagnesaemia are not linked to long QT syndrome.
Long QT syndrome (LQTS) is a genetic condition that causes a delay in the ventricles’ repolarization. This delay can lead to ventricular tachycardia/torsade de pointes, which can cause sudden death or collapse. The most common types of LQTS are LQT1 and LQT2, which are caused by defects in the alpha subunit of the slow delayed rectifier potassium channel. A normal corrected QT interval is less than 430 ms in males and 450 ms in females.
There are various causes of a prolonged QT interval, including congenital factors, drugs, and other conditions. Congenital factors include Jervell-Lange-Nielsen syndrome and Romano-Ward syndrome. Drugs that can cause a prolonged QT interval include amiodarone, sotalol, tricyclic antidepressants, and selective serotonin reuptake inhibitors. Other factors that can cause a prolonged QT interval include electrolyte imbalances, acute myocardial infarction, myocarditis, hypothermia, and subarachnoid hemorrhage.
LQTS may be detected on a routine ECG or through family screening. Long QT1 is usually associated with exertional syncope, while Long QT2 is often associated with syncope following emotional stress, exercise, or auditory stimuli. Long QT3 events often occur at night or at rest and can lead to sudden cardiac death.
Management of LQTS involves avoiding drugs that prolong the QT interval and other precipitants if appropriate. Beta-blockers are often used, and implantable cardioverter defibrillators may be necessary in high-risk cases. It is important to note that sotalol may exacerbate LQTS.
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This question is part of the following fields:
- Cardiovascular System
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Question 13
Correct
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Which of the following events is commonly observed in the arterioles of individuals with malignant hypertension?
Your Answer: Fibrinoid necrosis
Explanation:Arterioles of patients with malignant hypertension exhibit fibrinoid necrosis.
Understanding Cell Death: Necrosis and Apoptosis
Cell death can occur through two mechanisms: necrosis and apoptosis. Necrosis is characterized by a failure in bioenergetics, which leads to tissue hypoxia and the inability to generate ATP. This results in the loss of cellular membrane integrity, energy-dependent transport mechanisms, and ionic instability, leading to cellular lysis and the release of intracellular contents that may stimulate an inflammatory response. Different types of necrosis exist, including coagulative, colliquative, caseous, gangrene, fibrinoid, and fat necrosis, with the predominant pattern depending on the tissue type and underlying cause.
On the other hand, apoptosis, also known as programmed cell death, is an energy-dependent process that involves the activation of caspases triggered by intracellular signaling mechanisms. This results in DNA fragmentation, mitochondrial dysfunction, and nuclear and cellular shrinkage, leading to the formation of apoptotic bodies. Unlike necrosis, phagocytosis of the cell does not occur, and the cell degenerates into apoptotic bodies.
Understanding the mechanisms of cell death is crucial in various fields, including medicine, biology, and pathology. By identifying the type of cell death, clinicians and researchers can better understand the underlying causes and develop appropriate interventions.
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This question is part of the following fields:
- Cardiovascular System
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Question 14
Incorrect
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A 67-year-old man is admitted to the hospital with central crushing chest pain and undergoes a coronary angiogram. Arterial blockage can result from atherosclerosis, which can cause changes in the endothelium. What is an anticipated change in the endothelium?
Your Answer: Increased nitric oxide bioavailability
Correct Answer: Reduced nitric oxide bioavailability
Explanation:Fatty infiltration in the subendothelial space is associated with LDL particles, but the endothelium undergoes changes that include reduced nitric oxide bioavailability, proliferation, and pro-inflammatory and pro-oxidant effects.
Understanding Atherosclerosis and its Complications
Atherosclerosis is a complex process that occurs over several years. It begins with endothelial dysfunction triggered by factors such as smoking, hypertension, and hyperglycemia. This leads to changes in the endothelium, including inflammation, oxidation, proliferation, and reduced nitric oxide bioavailability. As a result, low-density lipoprotein (LDL) particles infiltrate the subendothelial space, and monocytes migrate from the blood and differentiate into macrophages. These macrophages that phagocytose oxidized LDL, slowly turning into large ‘foam cells’. Smooth muscle proliferation and migration from the tunica media into the intima result in the formation of a fibrous capsule covering the fatty plaque.
Once a plaque has formed, it can cause several complications. For example, it can form a physical blockage in the lumen of the coronary artery, leading to reduced blood flow and oxygen to the myocardium, resulting in angina. Alternatively, the plaque may rupture, potentially causing a complete occlusion of the coronary artery and resulting in a myocardial infarction. It is essential to understand the process of atherosclerosis and its complications to prevent and manage cardiovascular diseases effectively.
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This question is part of the following fields:
- Cardiovascular System
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Question 15
Correct
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A 42-year-old man arrives at the emergency department with complaints of palpitations and dizziness. He has been experiencing vomiting and diarrhoea for the past week and has also been suffering from muscle weakness and cramps for the last three days. The possibility of hypokalaemia is suspected, and an ECG is ordered. What ECG sign is indicative of hypokalaemia?
Your Answer: Small or inverted T waves
Explanation:Hypokalaemia, a condition characterized by low levels of potassium in the blood, can be detected through ECG features. These include the presence of U waves, small or absent T waves (which may occasionally be inverted), a prolonged PR interval, ST depression, and a long QT interval. The ECG image provided shows typical U waves and a borderline PR interval. To remember these features, one user suggests the following rhyme: In Hypokalaemia, U have no Pot and no T, but a long PR and a long QT.
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This question is part of the following fields:
- Cardiovascular System
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Question 16
Incorrect
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A 54-year-old man visits the clinic with a complaint of experiencing shortness of breath during physical activity. He denies any chest pain or coughing and has never smoked. During cardiac auscultation, an ejection systolic murmur is detected. Although a valvular defect is suspected as the cause of his symptoms, echocardiography reveals an atrial septal defect (ASD) instead. An ASD allows blood to flow between the left and right atria. During fetal development, what structure connects the left and right atria?
Your Answer: Ductus arteriosus
Correct Answer: Foramen ovale
Explanation:The foramen ovale is an opening in the wall between the two upper chambers of the heart that allows blood to flow from the right atrium to the left atrium. Normally, this opening closes shortly after birth. However, if it remains open, it can result in a condition called patent foramen ovale, which is an abnormal connection between the two atria. This can lead to an atrial septal defect, where blood flows from the left atrium to the right atrium. This condition may be detected early if there are symptoms or a heart murmur is heard, but it can also go unnoticed until later in life.
During fetal development, the ductus venosus is a blood vessel that connects the umbilical vein to the inferior vena cava, allowing oxygenated blood to bypass the liver. After birth, this vessel usually closes and becomes the ligamentum venosum.
The ductus arteriosus is another fetal blood vessel that connects the pulmonary artery to the aorta, allowing blood to bypass the non-functioning lungs. This vessel typically closes after birth and becomes the ligamentum arteriosum. If it remains open, it can result in a patent ductus arteriosus.
The coronary sinus is a vein that receives blood from the heart’s coronary veins and drains into the right atrium.
The mitral valve is a valve that separates the left atrium and the left ventricle of the heart.
The umbilical vein carries oxygenated blood from the placenta to the fetus during development. After birth, it typically closes and becomes the round ligament of the liver.
Understanding Patent Foramen Ovale
Patent foramen ovale (PFO) is a condition that affects approximately 20% of the population. It is characterized by the presence of a small hole in the heart that may allow an embolus, such as one from deep vein thrombosis, to pass from the right side of the heart to the left side. This can lead to a stroke, which is known as a paradoxical embolus.
Aside from its association with stroke, PFO has also been linked to migraine. Studies have shown that some patients experience an improvement in their migraine symptoms after undergoing PFO closure.
The management of PFO in patients who have had a stroke is still a topic of debate. Treatment options include antiplatelet therapy, anticoagulant therapy, or PFO closure. It is important for patients with PFO to work closely with their healthcare provider to determine the best course of action for their individual needs.
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This question is part of the following fields:
- Cardiovascular System
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Question 17
Incorrect
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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: HMG-CoA reductase inhibitor
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.
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This question is part of the following fields:
- Cardiovascular System
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Question 18
Incorrect
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An 80-year-old patient comes in for a routine follow-up appointment and reports a decline in exercise tolerance. They mention having difficulty with stairs and experiencing occasional central chest pain that radiates to their back, which is relieved by rest. The pain is not present at rest.
During the examination, you observe a regular, slow-rising pulse and record a blood pressure of 110/95mmHg. Upon auscultation of the precordium, you detect an ejection systolic murmur.
To further assess cardiac function and valves, an echocardiogram is scheduled. Based on the likely diagnosis, what additional exam findings are you most likely to discover?Your Answer: Quincke's sign
Correct Answer: Fourth heart sound (S4)
Explanation:The patient’s symptoms and physical exam suggest the presence of aortic stenosis. This is indicated by the ejection systolic murmur, slow-rising pulse, and progressive heart failure symptoms. The fourth heart sound (S4) is also present, which occurs when the left atrium contracts forcefully to compensate for a stiff ventricle. In aortic stenosis, the left ventricle is hypertrophied due to the narrowed valve, leading to the S4 sound.
While hepatomegaly is more commonly associated with right heart valvular disease, it is not entirely ruled out in this case. However, the patient’s history is more consistent with aortic stenosis.
Malar flush, a pink flushed appearance across the cheeks, is typically seen in mitral stenosis due to hypercarbia causing arteriole vasodilation.
Pistol shot femoral pulses, a sound heard during systole when auscultating the femoral artery, is a finding associated with aortic regurgitation and not present in this case.
Heart sounds are the sounds produced by the heart during its normal functioning. The first heart sound (S1) is caused by the closure of the mitral and tricuspid valves, while the second heart sound (S2) is due to the closure of the aortic and pulmonary valves. The intensity of these sounds can vary depending on the condition of the valves and the heart. The third heart sound (S3) is caused by the diastolic filling of the ventricle and is considered normal in young individuals. However, it may indicate left ventricular failure, constrictive pericarditis, or mitral regurgitation in older individuals. The fourth heart sound (S4) may be heard in conditions such as aortic stenosis, HOCM, and hypertension, and is caused by atrial contraction against a stiff ventricle. The different valves can be best heard at specific sites on the chest wall, such as the left second intercostal space for the pulmonary valve and the right second intercostal space for the aortic valve.
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This question is part of the following fields:
- Cardiovascular System
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Question 19
Incorrect
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Where are the arterial baroreceptors situated?
Your Answer: External carotid artery
Correct Answer: Carotid sinus and aortic arch
Explanation:The heart has four chambers and generates pressures of 0-25 mmHg on the right side and 0-120 mmHg on the left. The cardiac output is the product of heart rate and stroke volume, typically 5-6L per minute. The cardiac impulse is generated in the sino atrial node and conveyed to the ventricles via the atrioventricular node. Parasympathetic and sympathetic fibers project to the heart via the vagus and release acetylcholine and noradrenaline, respectively. The cardiac cycle includes mid diastole, late diastole, early systole, late systole, and early diastole. Preload is the end diastolic volume and afterload is the aortic pressure. Laplace’s law explains the rise in ventricular pressure during the ejection phase and why a dilated diseased heart will have impaired systolic function. Starling’s law states that an increase in end-diastolic volume will produce a larger stroke volume up to a point beyond which stroke volume will fall. Baroreceptor reflexes and atrial stretch receptors are involved in regulating cardiac output.
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This question is part of the following fields:
- Cardiovascular System
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Question 20
Incorrect
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Which one of the following nerves is not found in the posterior triangle of the neck?
Your Answer:
Correct Answer: Ansa cervicalis
Explanation:The anterior triangle of the neck contains the ansa cervicalis.
The posterior triangle of the neck is an area that is bound by the sternocleidomastoid and trapezius muscles, the occipital bone, and the middle third of the clavicle. Within this triangle, there are various nerves, vessels, muscles, and lymph nodes. The nerves present include the accessory nerve, phrenic nerve, and three trunks of the brachial plexus, as well as branches of the cervical plexus such as the supraclavicular nerve, transverse cervical nerve, great auricular nerve, and lesser occipital nerve. The vessels found in this area are the external jugular vein and subclavian artery. Additionally, there are muscles such as the inferior belly of omohyoid and scalene, as well as lymph nodes including the supraclavicular and occipital nodes.
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This question is part of the following fields:
- Cardiovascular System
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