Lown-Ganong-Levine (LGL) syndrome is a condition that affects the electrical conducting system of the heart. It is classified as a pre-excitation syndrome, similar to the more well-known Wolff-Parkinson-White (WPW) syndrome. However, unlike WPW syndrome, LGL syndrome does not involve an accessory pathway for conduction. Instead, it is believed that there may be accessory fibers present that bypass all or part of the atrioventricular node.

When looking at an electrocardiogram (ECG) of a patient with LGL syndrome in sinus rhythm, there are several characteristic features to observe. The PR interval, which represents the time it takes for the electrical signal to travel from the atria to the ventricles, is typically shortened and measures less than 120 milliseconds. The QRS duration, which represents the time it takes for the ventricles to contract, is normal. The P wave, which represents the electrical activity of the atria, may be normal or inverted. However, what distinguishes LGL syndrome from other pre-excitation syndromes is the absence of a delta wave, which is a slurring of the initial rise in the QRS complex.

It is important to note that LGL syndrome predisposes individuals to paroxysmal supraventricular tachycardia (SVT), a rapid heart rhythm that originates above the ventricles. However, it does not increase the risk of developing atrial fibrillation or flutter, which are other types of abnormal heart rhythms.

Tenecteplase is a medication known as a tissue plasminogen activator (tPA). Its main mechanism of action involves binding specifically to fibrin and converting plasminogen into plasmin. This process leads to the breakdown of the fibrin matrix and promotes reperfusion at the affected site. Among the options provided, Tenecteplase is the sole drug that primarily acts by facilitating reperfusion.

Mitral regurgitation is characterized by several clinical features. One of the main signs is a pansystolic murmur that can be heard throughout the entire systolic phase of the cardiac cycle. This murmur often radiates to the left axilla. Another notable feature is a soft S1 heart sound, which is the first heart sound heard during the cardiac cycle. Additionally, a 3rd heart sound, also known as an added sound, can be detected in patients with mitral regurgitation. As the condition progresses to moderate to severe levels, signs such as a laterally displaced apex beat with a heave may become apparent.

Further Reading:

Mitral Stenosis:
– Causes: Rheumatic fever, Mucopolysaccharidoses, Carcinoid, Endocardial fibroelastosis
– Features: Mid-late diastolic murmur, loud S1, opening snap, low volume pulse, malar flush, atrial fibrillation, signs of pulmonary edema, tapping apex beat
– Features of severe mitral stenosis: Length of murmur increases, opening snap becomes closer to S2
– Investigation findings: CXR may show left atrial enlargement, echocardiography may show reduced cross-sectional area of the mitral valve

Mitral Regurgitation:
– Causes: Mitral valve prolapse, Myxomatous degeneration, Ischemic heart disease, Rheumatic fever, Connective tissue disorders, Endocarditis, Dilated cardiomyopathy
– Features: pansystolic murmur radiating to left axilla, soft S1, S3, laterally displaced apex beat with heave
– Signs of acute MR: Decompensated congestive heart failure symptoms
– Signs of chronic MR: Leg edema, fatigue, arrhythmia (atrial fibrillation)
– Investigation findings: Doppler echocardiography to detect regurgitant flow and pulmonary hypertension, ECG may show signs of LA enlargement and LV hypertrophy, CXR may show LA and LV enlargement in chronic MR and pulmonary edema in acute MR.

Hypertrophic obstructive cardiomyopathy (HOCM) is a primary heart disease characterized by the enlargement of the myocardium in the left and right ventricles. It is the most common reason for sudden cardiac death in young individuals and athletes. HOCM can be inherited in an autosomal dominant manner, and a family history of unexplained sudden death is often present.

Symptoms that may be experienced in HOCM include palpitations, breathlessness, chest pain, and syncope. Clinical signs that can be observed in HOCM include a jerky pulse character, a double apical impulse (where both atrial and ventricular contractions can be felt), a thrill at the left sternal edge, and an ejection systolic murmur at the left sternal edge that radiates throughout the praecordium. Additionally, a 4th heart sound may be present due to blood hitting a stiff and enlarged left ventricle during atrial systole.

On the other hand, Brugada syndrome is another cause of sudden cardiac death, but patients with this condition are typically asymptomatic and have a normal clinical examination.

Pericardial friction rub is a common finding in pericarditis and is often described as a sound similar to squeaking leather. This patient exhibits symptoms that are consistent with acute pericarditis, including flu-like illness with muscle pain and fatigue, chest pain that worsens when lying down and improves when sitting up or leaning forward, and the presence of a pleural rub. The gradual onset of symptoms rules out conditions like pulmonary embolism or acute myocardial ischemia. It is important to note that while the pericardial rub is often considered part of the classic triad of clinical features, it is only present in about one-third of patients. Additionally, the rub may come and go, so repeated examinations may increase the chances of detecting this sign.

Further Reading:

Pericarditis is an inflammation of the pericardium, which is the protective sac around the heart. It can be acute, lasting less than 6 weeks, and may present with chest pain, cough, dyspnea, flu-like symptoms, and a pericardial rub. The most common causes of pericarditis include viral infections, tuberculosis, bacterial infections, uremia, trauma, and autoimmune diseases. However, in many cases, the cause remains unknown. Diagnosis is based on clinical features, such as chest pain, pericardial friction rub, and electrocardiographic changes. Treatment involves symptom relief with nonsteroidal anti-inflammatory drugs (NSAIDs), and patients should avoid strenuous activity until symptoms improve. Complicated cases may require treatment for the underlying cause, and large pericardial effusions may need urgent drainage. In cases of purulent effusions, antibiotic therapy is necessary, and steroid therapy may be considered for pericarditis related to autoimmune disorders or if NSAIDs alone are ineffective.

Torsades de pointes is a condition that is linked to low levels of potassium (hypokalaemia) and magnesium (hypomagnesaemia). When potassium and magnesium levels are low, it can cause the QT interval to become prolonged, which increases the risk of developing Torsades de pointes.

Further Reading:

Torsades de pointes is an irregular broad-complex tachycardia that can be life-threatening. It is a polymorphic ventricular tachycardia that can lead to sudden cardiac death. It is characterized by distinct features on the electrocardiogram (ECG).

The causes of irregular broad-complex tachycardia include atrial fibrillation with bundle branch block, atrial fibrillation with ventricular pre-excitation (in patients with Wolff-Parkinson-White syndrome), and polymorphic ventricular tachycardia such as torsades de pointes. However, sustained polymorphic ventricular tachycardia is unlikely to be present without adverse features, so it is important to seek expert help for the assessment and treatment of this condition.

Torsades de pointes can be caused by drug-induced QT prolongation, diarrhea, hypomagnesemia, hypokalemia, and congenital long QT syndrome. It may also be seen in malnourished individuals due to low potassium and/or low magnesium levels. Additionally, it can occur in individuals taking drugs that prolong the QT interval or inhibit their metabolism.

The management of torsades de pointes involves immediate action. All drugs known to prolong the QT interval should be stopped. Amiodarone should not be given for definite torsades de pointes. Electrolyte abnormalities, especially hypokalemia, should be corrected. Magnesium sulfate should be administered intravenously. If adverse features are present, immediate synchronized cardioversion should be arranged. sought, as other treatments such as overdrive pacing may be necessary to prevent relapse once the arrhythmia has been corrected. If the patient becomes pulseless, defibrillation should be attempted immediately.

In summary, torsades de pointes is a dangerous arrhythmia that requires prompt management. It is important to identify and address the underlying causes, correct electrolyte abnormalities, and seek expert help for appropriate treatment.

The timing of the initial rise, peak, and return to normality of various cardiac enzymes can serve as a helpful guide. Creatine kinase, the main cardiac isoenzyme, typically experiences an initial rise within 4-8 hours, reaches its peak at 18 hours, and returns to normal within 2-3 days. Myoglobin, which lacks specificity due to its association with skeletal muscle damage, shows an initial rise within 1-4 hours, peaks at 6-7 hours, and returns to normal within 24 hours. Troponin I, known for its sensitivity and specificity, exhibits an initial rise within 3-12 hours, reaches its peak at 24 hours, and returns to normal within 3-10 days. HFABP, or heart fatty acid binding protein, experiences an initial rise within 1.5 hours, peaks at 5-10 hours, and returns to normal within 24 hours. Lastly, LDH, predominantly found in cardiac muscle, shows an initial rise at 10 hours, peaks at 24-48 hours, and returns to normal within 14 days.

Wolff-Parkinson-White (WPW) syndrome is a condition that affects the electrical system of the heart. It occurs when there is an abnormal pathway, known as the bundle of Kent, between the atria and the ventricles. This pathway can cause premature contractions of the ventricles, leading to a type of rapid heartbeat called atrioventricular re-entrant tachycardia (AVRT).

In a normal heart rhythm, the electrical signals travel through the bundle of Kent and stimulate the ventricles. However, in WPW syndrome, these signals can cause the ventricles to contract prematurely. This can be seen on an electrocardiogram (ECG) as a shortened PR interval, a slurring of the initial rise in the QRS complex (known as a delta wave), and a widening of the QRS complex.

There are two distinct types of WPW syndrome that can be identified on an ECG. Type A is characterized by predominantly positive delta waves and QRS complexes in the praecordial leads, with a dominant R wave in V1. This can sometimes be mistaken for right bundle branch block (RBBB). Type B, on the other hand, shows predominantly negative delta waves and QRS complexes in leads V1 and V2, and positive in the other praecordial leads, resembling left bundle branch block (LBBB).

Overall, WPW syndrome is a condition that affects the electrical conduction system of the heart, leading to abnormal heart rhythms. It can be identified on an ECG by specific features such as shortened PR interval, delta waves, and widened QRS complex.

Distinguishing between unstable angina and other acute coronary syndromes can be determined by normal troponin results. Unstable angina is characterized by new onset angina or a sudden worsening of previously stable angina, often occurring at rest. This condition typically requires hospital admission. On the other hand, stable angina is predictable and occurs during physical exertion or emotional stress, lasting for a short duration of no more than 10 minutes and relieved within minutes of rest or sublingual nitrates.

To diagnose unstable angina, it is crucial to consider the nature of the chest pain and negative cardiac enzyme testing. The presence or absence of chest pain at rest and the response to rest and treatment with GTN are the most useful descriptors in distinguishing between stable and unstable angina. It is important to note that patients with unstable angina may not exhibit any changes on an electrocardiogram (ECG).

If troponin results are abnormal, it indicates a myocardial infarction rather than unstable angina.

Further Reading:

Acute Coronary Syndromes (ACS) is a term used to describe a group of conditions that involve the sudden reduction or blockage of blood flow to the heart. This can lead to a heart attack or unstable angina. ACS includes ST segment elevation myocardial infarction (STEMI), non-ST segment elevation myocardial infarction (NSTEMI), and unstable angina (UA).

The development of ACS is usually seen in patients who already have underlying coronary heart disease. This disease is characterized by the buildup of fatty plaques in the walls of the coronary arteries, which can gradually narrow the arteries and reduce blood flow to the heart. This can cause chest pain, known as angina, during physical exertion. In some cases, the fatty plaques can rupture, leading to a complete blockage of the artery and a heart attack.

There are both non modifiable and modifiable risk factors for ACS. non modifiable risk factors include increasing age, male gender, and family history. Modifiable risk factors include smoking, diabetes mellitus, hypertension, hypercholesterolemia, and obesity.

The symptoms of ACS typically include chest pain, which is often described as a heavy or constricting sensation in the central or left side of the chest. The pain may also radiate to the jaw or left arm. Other symptoms can include shortness of breath, sweating, and nausea/vomiting. However, it’s important to note that some patients, especially diabetics or the elderly, may not experience chest pain.

The diagnosis of ACS is typically made based on the patient’s history, electrocardiogram (ECG), and blood tests for cardiac enzymes, specifically troponin. The ECG can show changes consistent with a heart attack, such as ST segment elevation or depression, T wave inversion, or the presence of a new left bundle branch block. Elevated troponin levels confirm the diagnosis of a heart attack.

The management of ACS depends on the specific condition and the patient’s risk factors. For STEMI, immediate coronary reperfusion therapy, either through primary percutaneous coronary intervention (PCI) or fibrinolysis, is recommended. In addition to aspirin, a second antiplatelet agent is usually given. For NSTEMI or unstable angina, the treatment approach may involve reperfusion therapy or medical management, depending on the patient’s risk of future cardiovascular events.

Cardiac enzymes do not increase in unstable angina. However, if cardiac markers do rise, it is classified as a non-ST elevation myocardial infarction (NSTEMI). Both unstable angina and NSTEMI can have a normal ECG. An extended ventricular activation time indicates damage to the heart muscle. This occurs because infarcting myocardium conducts electrical impulses at a slower pace, resulting in a prolonged interval between the start of the QRS complex and the apex of the R wave. A positive troponin test indicates the presence of necrosis in cardiac myocytes.

Summary:
Marker | Initial Rise | Peak | Normal at
Creatine kinase | 4-8 hours | 18 hours 2-3 days | CK-MB = main cardiac isoenzyme
Myoglobin | 1-4 hours | 6-7 hours | 24 hours | Low specificity due to skeletal muscle damage
Troponin I | 3-12 hours | 24 hours | 3-10 days | Appears to be the most sensitive and specific
HFABP | 1-2 hours | 5-10 hours | 24 hours | HFABP = heart fatty acid binding protein
LDH | 10 hours | 24-48 hours | 14 days | Cardiac muscle mainly contains LDH