Dr. Usman's Cardiology Notes

  Heart Blocks on ECG: A Practical Guide to First-, Second- and Third-Degree AV Block Atrioventricular (AV) block is one of the most important conduction abnormalities encountered on ECG. Correctly identifying the pattern—particularly distinguishing Mobitz I from Mobitz II—has major implications for prognosis, monitoring and pacemaker therapy. The key is to systematically assess the relationship between P waves, PR intervals and QRS complexes. --- 1. What is AV Block? AV block occurs when conduction of electrical impulses from the atria to the ventricles is delayed or interrupted at the AV node, His bundle or Purkinje system. It is broadly classified as: 1. First-degree AV block 2. Second-degree AV block Mobitz I / Wenckebach Mobitz II 2:1 AV block High-grade/advanced AV block 3. Third-degree AV block / complete heart block The ECG diagnosis depends primarily on identifying: P-wave behavior → PR interval → conducted/dropped QRS complexes → atrial–ventricular relationship. --- 2. Fi...

 5th Universal Definition of Myocardial Infarction (2026) The Major Changes You Need to Know The Fifth Universal Definition of Myocardial Infarction (5th UDMI), published in 2026, represents a major evolution in how myocardial infarction (MI) is defined and classified. For the first time, the document has been developed jointly by the European Society of Cardiology (ESC), American College of Cardiology (ACC), American Heart Association (AHA), and World Heart Federation (WHF). The major conceptual change is simple: Instead of asking, “Is this Type 1, 2, 3, 4 or 5 MI?” the clinician should now ask: Is this a primary MI, secondary MI, or procedure-related MI? The new classification is designed to better reflect pathophysiology and clinical decision-making. --- 1. What is Myocardial Infarction? Myocardial infarction is myocardial cell death caused by prolonged myocardial ischaemia. Importantly, an elevated troponin level alone does NOT diagnose MI. The clinical diagnosis requires: Acut...

 🫀 MECHANICAL AORTIC VALVE — ECHOCARDIOGRAPHIC ASSESSMENT 🔍 How to assess a mechanical aortic prosthesis by Echo? Mechanical prosthetic valves require a systematic echocardiographic assessment. The most important point is: ⚠️ DO NOT diagnose prosthetic valve obstruction from a high gradient alone! --- 1️⃣ 2D ECHOCARDIOGRAPHY Assess: 🔹 Valve position and seating 🔹 Prosthetic leaflet/disc mobility when visible 🔹 Abnormal rocking motion of the prosthesis 🔹 Thrombus 🔹 Pannus 🔹 Vegetation 🔹 Dehiscence 🔹 Paravalvular abnormalities 🔹 Aortic root and ascending aorta 🔹 LV size, wall thickness and systolic function ⚠️ Mechanical valves produce significant acoustic shadowing and reverberation, therefore the prosthetic leaflets may not always be adequately visualized by TTE. --- 2️⃣ DOPPLER ASSESSMENT The essential Doppler parameters include: ✅ Peak velocity (Vmax) ✅ Peak gradient ✅ Mean gradient ✅ Dimensionless Velocity Index (DVI) ✅ Acceleration time (AT) ✅ Effective orifice area...

2026 ESC Guidelines for the Management of Heart Failure — What Has Changed? The European Society of Cardiology has released the 2026 ESC Guidelines for the Management of Heart Failure, representing a major update to the contemporary approach to prevention, diagnosis, classification and treatment of heart failure. The new guideline moves beyond simply categorising patients according to left ventricular ejection fraction (LVEF). It introduces a more clinically oriented framework incorporating disease stages, phenotype, comorbidities, congestion, risk and treatment response. 1. A New Approach to Heart Failure Classification One of the important changes is refinement of the classification of HF according to LVEF. Rather than viewing HF as a single disease, the guideline emphasises the spectrum of ventricular function and the importance of recognising patients at different stages of disease. Broadly, clinical phenotypes continue to include: - HFrEF - HF with mildly reduced EF - HFpEF - HF w...

  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...