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...