Dr. Usman's Cardiology Notes

  Duchenne Muscular Dystrophy (DMD) — Key Points Overview Most common and severe childhood muscular dystrophy X-linked recessive disorder Caused by mutation in the DMD gene (Xp21) → absence of dystrophin Affects mainly boys; females are usually carriers Pathophysiology Dystrophin links: Cytoskeleton (actin) → sarcolemma → extracellular matrix Absence causes: Muscle fiber instability Repeated muscle injury Inflammation and fibrosis Progressive muscle weakness Clinical Features Onset: 2–5 years Progressive proximal muscle weakness: Pelvic girdle > shoulder girdle Difficulty: Running Climbing stairs Rising from floor Classic Signs Gowers sign (using hands to push on thighs to stand) Calf pseudohypertrophy (fat/fibrosis replacement) Waddling gait Frequent falls Toe walking Loss of ambulation usually by 10–13 years Laboratory Findings Markedly elevated CK (often >10,000 U/L) Elevated AST/ALT due to muscle injury Genetic testing confirms diagnosis Diagnosis 1. Genetic testing First...

 Vericiguat in Heart Failure: Mechanism, Indications, Dosing, Evidence and Clinical Use Vericiguat is an oral soluble guanylate cyclase (sGC) stimulator developed for patients with heart failure with reduced ejection fraction (HFrEF), particularly those who remain at high risk after a recent episode of worsening heart failure. Unlike the four foundational therapies of HFrEF, vericiguat is generally considered an additional treatment for selected high-risk patients rather than routine first-line therapy for every patient with reduced ejection fraction. Its clinical role became established largely through the VICTORIA trial, which demonstrated a reduction in the composite outcome of cardiovascular death or hospitalization for heart failure among patients with recently worsening HFrEF. --- What Is Vericiguat? Vericiguat is an oral soluble guanylate cyclase stimulator. It acts on the nitric oxide–soluble guanylate cyclase–cyclic guanosine monophosphate (NO–sGC–cGMP) pathway, an importa...

  Echocardiographic Assessment of Atrial Septal Defect (ASD): A Practical Guide Atrial septal defect (ASD) is one of the most common congenital heart defects encountered in adults. Echocardiography is the cornerstone of diagnosis because it not only demonstrates the defect but also determines its anatomical type, size, direction of shunting, hemodynamic significance, effects on the right heart, pulmonary artery pressure, and suitability for device closure. A good ASD echocardiographic examination should therefore answer more than simply: “Is an ASD present?” It should answer: What type of ASD is present? How large is the defect? What is the direction and magnitude of the shunt? Is there right ventricular volume overload? Is pulmonary hypertension present? Are the pulmonary veins normally connected? Is the anatomy suitable for transcatheter device closure? These elements form the basis of a systematic echocardiographic assessment. --- Types of Atrial Septal Defect An ASD should firs...

 Systolic Flow Reversal in Severe Tricuspid Regurgitation: An Important Doppler Sign Tricuspid regurgitation (TR) is increasingly recognized as an important determinant of symptoms, right-sided heart failure, hospitalization, and prognosis. Echocardiography remains the primary imaging modality for evaluating TR. Among the supportive Doppler findings of severe TR, systolic flow reversal in the hepatic veins is particularly useful. Current echocardiographic recommendations include hepatic vein systolic flow reversal among the important signs supporting severe TR. --- What Is Normal Hepatic Vein Flow? Hepatic venous flow can be assessed using pulsed-wave (PW) Doppler, usually from the subcostal window. A normal hepatic venous Doppler tracing contains: S wave: Forward flow toward the right atrium during ventricular systole. D wave: Forward flow during early ventricular diastole. A reversal wave: Brief retrograde flow during right atrial contraction. Normally, forward systolic flow is p...

Noninfarction Q Waves on ECG: Differential Diagnosis and Clinical Approach Q waves on an electrocardiogram (ECG) are often associated with previous myocardial infarction (MI). However, an important clinical principle is: Not every Q wave represents myocardial infarction. Q waves can occur as normal variants or as a result of changes in cardiac position, ventricular hypertrophy, cardiomyopathy, myocardial infiltration, and conduction abnormalities. Recognizing these noninfarction Q waves is important because an incorrect diagnosis of previous MI may lead to unnecessary investigations, anxiety, and inappropriate treatment. This article provides a practical differential diagnosis of Q waves that may occur without myocardial infarction. --- What Is a Q Wave? A Q wave is the first negative deflection of the QRS complex occurring before the first positive deflection (R wave). Small Q waves can be entirely physiological because normal ventricular depolarization begins in the interventricular ...

Parameters of Right Ventricular Dysfunction on Echocardiography in Acute Pulmonary Embolism Acute pulmonary embolism (PE) can produce a sudden increase in pulmonary vascular resistance, resulting in acute right ventricular (RV) pressure overload, RV dilatation, impaired RV contractility, and eventually hemodynamic collapse. Echocardiography therefore plays an important role in identifying RV dysfunction, assessing the hemodynamic consequences of acute PE, and supporting risk stratification. Importantly, echocardiographic abnormalities should be interpreted in the overall clinical context because no single echocardiographic finding is sufficiently sensitive or specific to establish or exclude acute PE in most patients. --- Why Does the Right Ventricle Fail in Acute Pulmonary Embolism? When a significant portion of the pulmonary arterial circulation becomes obstructed, pulmonary vascular resistance rises abruptly. The thin-walled right ventricle is poorly adapted to a sudden increase in ...

  Oral Antiplatelet Dosing in ACS — High-Yield Guide Acute coronary syndrome (ACS) includes STEMI, NSTEMI, and unstable angina. Antiplatelet therapy is a cornerstone of treatment because platelet activation and aggregation play a central role in coronary thrombus formation. In most patients with ACS, treatment involves dual antiplatelet therapy (DAPT): Aspirin + a P2Y12 receptor inhibitor The commonly used oral P2Y12 inhibitors are clopidogrel, prasugrel, and ticagrelor. --- 1. Aspirin Aspirin irreversibly inhibits cyclooxygenase-1 (COX-1), reducing thromboxane A₂ production and platelet aggregation. Loading Dose 162–325 mg orally Chewable, non-enteric-coated aspirin is preferred when rapid platelet inhibition is required. Maintenance Dose 75–100 mg once daily A commonly used maintenance dose is 81 mg/day. High-Yield Point Aspirin should generally be given as early as possible in ACS unless there is a true contraindication, such as significant active bleeding or serious aspirin hyp...