Treatment Options for Ventricular Tachycardia: Synchronised Cardioversion and Amiodarone

Ventricular tachycardia is a serious condition that requires immediate treatment. The Resuscitation Council tachycardia guideline recommends synchronised electrical cardioversion as the first-line treatment for unstable patients with ventricular tachycardia who exhibit adverse features such as shock, myocardial ischaemia, syncope, or heart failure. Synchronised cardioversion is timed to coincide with the R or S wave of the QRS complex, reducing the risk of ventricular fibrillation or cardiac arrest.

Administering an unsynchronised shock could coincide with the T wave, triggering fibrillation of the ventricles and leading to a cardiac arrest. If three attempts of synchronised cardioversion fail to restore sinus rhythm, a loading dose of amiodarone 300 mg iv should be given over 10–20 minutes, followed by another attempt of cardioversion.

Amiodarone is the first-line treatment for uncompromised patients with tachycardia. A loading dose of 300 mg is given iv, followed by an infusion of 900 mg over 24 hours. Digoxin and metoprolol are not recommended for the treatment of ventricular tachycardia. Digoxin is used for atrial fibrillation, while metoprolol should be avoided in patients with significant hypotension, as it can further compromise the patient’s condition.

Common Endocrine Disorders and their Cardiac Manifestations

Endocrine disorders can have significant effects on the cardiovascular system, including the development of arrhythmias. Atrial fibrillation is a common arrhythmia that can be caused by hyperthyroidism, which should be tested for in patients presenting with this condition. Other signs of thyrotoxicosis include sinus tachycardia, physiological tremor, lid lag, and lid retraction. Graves’ disease, a common cause of hyperthyroidism, can also present with pretibial myxoedema, proptosis, chemosis, and thyroid complex ophthalmoplegia. Mnemonics such as SHIMMERS and ABCD can be used to remember the causes and management of atrial fibrillation.

Cushing syndrome, hyperparathyroidism, and hypothyroidism can also have cardiac manifestations, although they are not typically associated with arrhythmias. Cushing syndrome is not commonly associated with arrhythmias, while hyperparathyroidism can cause hypercalcemia, leading to non-specific symptoms such as aches and pains, dehydration, fatigue, mood disturbance, constipation, and renal stones. Hypothyroidism, on the other hand, may cause bradycardia and can be caused by various factors such as Hashimoto’s thyroiditis, subacute thyroiditis, iodine deficiency, and iatrogenic factors such as post-carbimazole treatment, radio-iodine, thyroidectomy, and certain medications like lithium and amiodarone.

In summary, endocrine disorders can have significant effects on the cardiovascular system, and it is important to be aware of their potential cardiac manifestations, including arrhythmias. Early detection and management of these conditions can help prevent serious complications and improve patient outcomes.

Understanding ECG Analysis: The Normal Cardiac Axis

ECG analysis is a fundamental concept that is essential to understand early on. One of the key components of ECG analysis is the normal cardiac axis, which ranges from −30 to 90 degrees. If the axis is greater than 90 degrees, it implies right axis deviation, while an axis less than −30 degrees indicates left axis deviation.

To determine the axis, leads I, II, and III of the ECG are typically examined. A normal axis is characterized by upgoing waves in all three leads. In contrast, right axis deviation is indicated by a downgoing wave in lead I and an upgoing wave in leads II and III. Left axis deviation is indicated by an upgoing wave in lead I and a downgoing wave in leads II and III.

While −30 to −90 degrees is considered left axis deviation and not a normal axis, −30 to 60 degrees is a normal axis, but it does not cover the full spectrum of a normal axis. Therefore, the correct answer is -30 to 90 degrees. Understanding the normal cardiac axis is crucial for accurate ECG interpretation and diagnosis.

Different Cusps of Heart Valves

The heart has four valves that regulate blood flow through the chambers. Each valve is composed of cusps, which are flaps that open and close to allow blood to pass through. Here are the different cusps of each heart valve:

Aortic Valve: The aortic valve is made up of a right, left, and posterior cusp. It is located at the junction between the left ventricle and the ascending aorta.

Mitral Valve: The mitral valve is usually the only bicuspid valve and is composed of anterior and posterior cusps. It is located between the left atrium and the left ventricle.

Tricuspid Valve: The tricuspid valve has three cusps – anterior, posterior, and septal. It is located between the right atrium and the right ventricle.

Pulmonary Valve: The pulmonary valve is made up of right, left, and anterior cusps. It is located at the junction between the right ventricle and the pulmonary artery.

Understanding the different cusps of heart valves is important in diagnosing and treating heart conditions.

Possible Diagnosis for a Patient with Chronic Respiratory Infections and a Heart Murmur

Primary Ciliary Dyskinesia: A Congenital Syndrome of Ciliary Dysfunction

The patient described in the case likely has primary ciliary dyskinesia, also known as Kartagener’s syndrome, which is a congenital syndrome of ciliary dysfunction. This disorder affects the proper beating of Ciliary, leading to the accumulation of infectious material within the respiratory tree and abnormal cell migration during development, resulting in situs inversus. Additionally, abnormal Ciliary can lead to non-motile sperm and infertility.

Other Possible Diagnoses

Although the GP noticed a diastolic murmur suggestive of mitral stenosis, the patient does not have symptoms of congestive heart failure. Asthma could be associated with chronic lung and respiratory tract infections, but it would not explain the heart murmur. Squamous cell lung cancer is less likely in a man who is 40 years old with a normal respiratory examination and would not explain the heart murmur. Idiopathic pulmonary hypertension usually causes progressive breathlessness, a dry cough, and fine inspiratory crepitations on examination, rather than the picture here.

Medications for Acute Coronary Syndrome: Indications and Uses

Acute coronary syndrome (ACS) is a medical emergency that requires prompt and appropriate treatment to prevent further damage to the heart muscle. The management of ACS involves a combination of medications and interventions, depending on the type and severity of the condition. Here are some commonly used medications for ACS and their indications:

1. Fondaparinux: This medication is a factor Xa inhibitor that is used for anticoagulation in ACS without ST-segment elevation. It is usually given along with other drugs such as aspirin, clopidogrel, and nitrates to prevent blood clots and reduce the risk of future cardiovascular events.

2. Warfarin: This medication is used for the treatment and prevention of venous thrombosis and thromboembolism. It is not indicated for the immediate management of ACS.

3. Furosemide: This medication is a diuretic that is used to treat pulmonary edema in patients with heart failure. It is not indicated for ACS as it may cause dehydration.

4. Paracetamol: This medication is not effective as an analgesic option for ACS. Morphine is commonly used for pain relief in ACS.

5. Simvastatin: This medication is a statin that is used for the long-term management of high cholesterol levels. It is not indicated for the initial management of ACS.

In summary, the management of ACS involves a combination of medications and interventions that are tailored to the individual patient’s needs. Prompt and appropriate treatment can help improve outcomes and reduce the risk of future cardiovascular events.

Differentiating Arterial Conditions: Understanding the Symptoms and Causes

When it comes to arterial conditions, it is important to understand the symptoms and causes in order to make an accurate diagnosis. Here, we will explore several potential conditions and how they may present in a patient.

Stenotic Arteries:
Coarctation of the aorta is a potential condition to consider in younger adults with poorly controlled hypertension. Symptoms may include weak or absent femoral pulses, heart failure, and left-ventricular hypertrophy. Angiography may reveal stenosis in the middle and proximal segments of the left anterior descending artery, as well as in the left circumflex artery.

Thickened Arteries:
Atherosclerosis, or the build-up of plaque in the arteries, is a risk factor for heart attacks and stroke. However, it is unlikely to explain persistently high blood pressure or an absent femoral pulse.

Aortic Aneurysm:
While chronic high blood pressure can increase the risk of an aortic aneurysm, sudden, intense chest or back pain is a more common symptom. Additionally, a patient with an aneurysm would likely have low blood pressure and an elevated heart rate, which is inconsistent with the vitals seen in this presentation.

Calcified Arteries:
Calcification of arteries is caused by elevated lipid content and increases with age. While it can increase the risk of heart attack and stroke, it would not explain the absence of a femoral pulse or extremely high blood pressure.

Patent Foramen Ovale:
This condition, which predisposes patients to paradoxical emboli, is typically diagnosed on an echocardiogram and is unlikely to cause hypertension. It should be considered in patients who have had a stroke before the age of 50.

In summary, understanding the symptoms and causes of arterial conditions is crucial for accurate diagnosis and treatment.

Acute Rheumatic Fever

Acute rheumatic fever is a condition that occurs after a bacterial infection and is caused by pathogenic antibodies. It is characterized by a systemic inflammatory response that affects the heart, joints, and skin. The condition is triggered by antibodies that cross-react with cardiac tissue, which can lead to pancarditis, arthritis, and intra-dermal inflammation. The diagnosis of acute rheumatic fever is based on a combination of clinical and investigatory findings, which are known as the revised Jones criteria.

The pancarditis associated with acute rheumatic fever can cause a sustained tachycardia, which is particularly prominent at night. Conduction abnormalities, including prolonged PR interval, are also common. Pericarditis may be detected clinically with a pericardial rub, and patients may exhibit features of congestive cardiac failure, such as cardiomegaly. Several murmurs are recognized in patients with acute rheumatic fever, including aortic regurgitation, mitral regurgitation, and the Carey Coombs murmur.

In summary, acute rheumatic fever is a serious condition that can have significant effects on the heart, joints, and skin. Early diagnosis and treatment are essential to prevent complications and improve outcomes. The revised Jones criteria provide guidance for clinicians in making an accurate diagnosis and initiating appropriate treatment.

Understanding Different Types of Heart Blocks on an ECG

An electrocardiogram (ECG) is a diagnostic tool used to monitor the electrical activity of the heart. It can help identify different types of heart blocks, which occur when the electrical signals that control the heartbeat are disrupted. Here are some common types of heart blocks and how they appear on an ECG:

Second Degree Heart Block – Mobitz Type II
This type of heart block is characterized by a regular non-conducted P-wave on the ECG. It may also show a widened QRS, indicating that the block is in the bundle branches of Purkinje fibers. If a patient is symptomatic with Mobitz type II heart block, permanent pacing is required to prevent progression to third degree heart block.

Third Degree Heart Block
An ECG of a third degree heart block would show dissociated P-waves and QRS-waves. This means that the atria and ventricles are not communicating properly, and the heart may beat very slowly or irregularly.

Atrial Flutter
Atrial flutter on an ECG would typically show a saw-toothed baseline. This occurs when the atria are beating too quickly and not in sync with the ventricles.

Ectopic Beats
Ectopic beats are premature heartbeats that occur outside of the normal rhythm. They would not result in regular non-conducted P-waves on an ECG.

Second Degree Heart Block – Mobitz Type I
Mobitz type I heart block would typically show progressive lengthening of the PR interval over several complexes, before a non-conducted P-wave would occur. This type of heart block is usually not as serious as Mobitz type II, but may still require monitoring and treatment.

The patient in the scenario is experiencing a fast rhythm with wide complexes, which is likely ventricular tachycardia (VT). As the patient is unstable, electrical cardioversion was attempted first, as recommended by the Resuscitation Council Guideline. If cardioversion fails and the patient remains unstable, intravenous amiodarone can be used as a loading dose of 300 mg over 10-20 minutes, followed by an infusion of 900 mg/24 hours. Amiodarone is a class III anti-arrhythmic agent that prolongs the repolarization phase of the cardiac action potential by blocking potassium efflux. Side-effects associated with amiodarone include deranged thyroid and liver function tests, nausea, vomiting, bradycardia, interstitial lung disease, jaundice, and sleep disorders.

Epinephrine is used in the treatment of acute anaphylaxis and cardiopulmonary resuscitation. It acts on adrenergic receptors, causing bronchodilation and vasoconstriction. Side-effects associated with epinephrine include palpitations, arrhythmias, headache, tremor, and hypertension.

Intravenous propranolol is a non-selective β-adrenergic receptor blocker that has limited use in treating arrhythmias and thyrotoxic crisis. It is contraindicated in patients with severe hypotension, asthma, COPD, bradycardia, sick sinus rhythm, atrioventricular block, and cardiogenic shock. Side-effects associated with propranolol include insomnia, nightmares, nausea, diarrhea, bronchospasm, exacerbation of Raynaud’s, bradycardia, hypotension, and heart block.

Digoxin, a cardiac glycoside extracted from the plant genus Digitalis, can be used in the treatment of supraventricular arrhythmias and heart failure. However, it is of no use in this scenario as the patient is experiencing a broad complex tachycardia. Digoxin has a narrow therapeutic window, and even small changes in dosing can lead to toxicity. Side-effects associated with digoxin include nausea, vomiting, diarrhea, bradycardia, dizziness, yellow vision, and eosinophilia.

Diltiazem, a non-dihydropyridine calcium channel blocker, is normally used for hypertension and prophylaxis and treatment of ang