Dr. Usman's Cardiology Notes

  COMPANION Trial (Comparison of Medical Therapy, Pacing, and Defibrillation in Heart Failure) Heart failure with reduced ejection fraction (HFrEF) remains a major cause of morbidity and mortality despite advances in pharmacological therapy. Electrical dyssynchrony, reflected by a wide QRS complex, contributes significantly to progressive ventricular dysfunction. The COMPANION trial was a landmark study that established the role of cardiac resynchronization therapy (CRT), with or without a defibrillator, in patients with advanced heart failure. --- Background and Rationale Prior to COMPANION, optimal medical therapy (OMT) was the cornerstone of heart failure management. However, many patients with severe systolic dysfunction and prolonged QRS continued to experience recurrent hospitalizations and high mortality. CRT was developed to correct interventricular and intraventricular dyssynchrony by simultaneous pacing of both ventricles. COMPANION was designed to determine whether addin...

Bundle Branch Block Morphology on ECG Understanding bundle branch block (BBB) patterns on ECG is a core skill for clinicians, residents, and cardiology trainees. BBB alters ventricular depolarization, producing characteristic QRS morphologies that are best appreciated by systematically comparing leads V1 and V6. Once you train your eye, these patterns become instantly recognizable and clinically meaningful. Normal Ventricular Conduction on ECG In normal conduction, electrical impulses travel simultaneously down the right and left bundle branches, leading to near-synchronous activation of both ventricles. In lead V1, the QRS complex is usually predominantly negative, reflecting left ventricular dominance, while in lead V6 there is a tall, narrow R wave representing efficient left ventricular depolarization. The QRS duration remains narrow, typically less than 120 ms, and ST-T segments follow the QRS direction smoothly. These normal patterns form the baseline against which bundle branch ...

  Diastology on echocardiography refers to the assessment of left ventricular (LV) filling, relaxation, compliance, and filling pressures. It is a core component of modern echo practice because many patients with heart failure, hypertension, diabetes, ischemia, or valvular disease have preserved systolic function but significant diastolic dysfunction. --- Why Diastolic Assessment Matters • Explains symptoms in patients with normal ejection fraction • Essential for diagnosing HFpEF • Reflects myocardial ischemia, fibrosis, and hypertrophy earlier than systolic indices • Guides prognosis and management Diastolic dysfunction often precedes systolic dysfunction. --- Physiology of Diastole (Echo Perspective) Diastole has four functional phases: 1. Isovolumic relaxation 2. Early rapid filling 3. Diastasis 4. Atrial contraction Echo parameters are designed to interrogate these phases. --- Core Echocardiographic Parameters in Diastology 1. Mitral Inflow Doppler Measured using pulsed-wave D...

Cardiac output is one of the most powerful bedside concepts in cardiology and critical care. It connects physiology, echocardiography, and real-time clinical decision-making, especially in unstable patients where numbers matter less than trends and response to intervention. Cardiac output is the volume of blood pumped by the heart per minute. It reflects how effectively the heart meets the metabolic demands of the body. In simple terms, it answers a crucial question: is tissue perfusion adequate? The physiological relationship is straightforward. Cardiac Output = Stroke Volume × Heart Rate What makes this concept clinically rich is how stroke volume is derived and how dynamically it changes with preload, afterload, and contractility. Echocardiographic calculation of cardiac output relies on left ventricular outflow tract (LVOT) measurements. The LVOT is treated as a circular conduit through which blood exits the left ventricle. First, the LVOT diameter is measured in the parasternal lo...

Lesion with High Calcium Content on Coronary Angiogram Definition A lesion with high calcium content refers to a coronary artery stenosis containing extensive calcium deposition within the intimal and/or medial layers of the vessel wall. On coronary angiography, these lesions appear as radiopaque (white), rigid segments that move synchronously with the cardiac cycle and persist throughout contrast injection. --- Pathophysiology Coronary calcification is a manifestation of advanced atherosclerosis and represents chronic vascular inflammation and healing. Key mechanisms include: Transformation of vascular smooth muscle cells into osteoblast-like cells Deposition of hydroxyapatite crystals Recurrent plaque injury and repair Association with aging, diabetes mellitus, chronic kidney disease, and long-standing hypertension Calcium can be superficial (intimal), deep (medial), or circumferential, each influencing interventional outcomes differently. --- Angiographic Characteristics On coronary...

Knuckle Sign on ECG: A Simple Visual Clue to Acute Pericarditis The knuckle sign is a helpful electrocardiographic visual analogy used to recognize acute pericarditis, particularly by focusing attention on lead aVR. It combines characteristic ST- and PR-segment changes into an easily remembered pattern, improving bedside ECG interpretation. What Is the Knuckle Sign? The knuckle sign refers to the resemblance between: • PR-segment elevation with ST-segment depression in lead aVR • The flexed shape of a finger at the knuckle joint When viewed together, the upward deflection of the PR segment followed by a downward ST segment in aVR mimics the contour of a bent knuckle, hence the name. ECG Basis of the Knuckle Sign Acute pericarditis causes diffuse inflammation of the pericardium, leading to characteristic atrial and ventricular injury currents. Key ECG features include: • Diffuse ST-segment elevation (usually concave) in most leads • PR-segment depression in multiple leads (atrial injury...

  ECG Predictors of Atrial Fibrillation Early Electrical Clues Before the First Episode Atrial fibrillation (AF) is often preceded by subtle electrical changes on the surface electrocardiogram. Recognizing these predictors helps clinicians identify high-risk patients, guide closer monitoring, and initiate early preventive strategies. --- 1. P-Wave Abnormalities The P wave reflects atrial depolarization. Structural and electrical atrial remodeling alters its morphology and duration. • Prolonged P-wave duration (>120 ms) suggests atrial conduction delay • Notched or bifid P wave (P mitrale) indicates left atrial enlargement • Low-amplitude or flattened P waves reflect atrial fibrosis Clinical relevance: Prolonged P-wave duration is a strong, noninvasive predictor of future AF. --- 2. P-Wave Dispersion P-wave dispersion is the difference between maximum and minimum P-wave duration across ECG leads. • Normal: <40 ms • Increased dispersion (>40–50 ms) indicates heterogeneous at...