Dr. Usman's Cardiology Notes

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...

Cornell Duration Product in ECG: Detailed, Practical Guide for Clinicians Left ventricular hypertrophy (LVH) is a key marker of chronic pressure overload and adverse cardiovascular outcomes. Among ECG-based criteria, the Cornell Duration Product (CDP) improves diagnostic accuracy by combining voltage with QRS duration, making it superior to voltage-only criteria in many clinical settings. Concept and Rationale Traditional ECG criteria for LVH rely mainly on QRS voltage, which is influenced by body habitus, age, and sex. The Cornell Duration Product incorporates QRS duration, reflecting both myocardial mass and conduction time. This integration enhances sensitivity for detecting true anatomical LVH. What Is the Cornell Duration Product The Cornell Duration Product is calculated by multiplying the Cornell voltage by the QRS duration. Cornell voltage is defined as: • S wave amplitude in lead V3 • Plus R wave amplitude in lead aVL Cornell Duration Product = [S(V3) + R(aVL)] × QRS duration ...

Evaluation of Syncope With Electrocardiographic Monitoring Syncope is a common clinical problem encountered in cardiology and general medicine, ranging from benign reflex causes to potentially life-threatening cardiac arrhythmias. Electrocardiographic (ECG) monitoring plays a central role in identifying arrhythmic causes of syncope, particularly when initial history, examination, and baseline ECG are non-diagnostic. The choice of monitoring strategy depends largely on the patient’s clinical risk profile and the frequency of syncopal episodes. Role of ECG Monitoring in Syncope The primary objective of ECG monitoring in syncope is to establish a symptom–rhythm correlation. Detecting bradyarrhythmias, tachyarrhythmias, pauses, or advanced conduction disease during a syncopal or pre-syncopal event can directly guide definitive management, including pacemaker implantation, catheter ablation, or antiarrhythmic therapy. Types of ECG Monitoring and Their Indications In-hospital (Telemetric) Mo...

AHA 2025 Guidelines – Acute Coronary Syndrome (ACS) Management – Key Points The 2025 ACC/AHA/ACEP/NAEMSP/SCAI Guideline for the Management of Patients With Acute Coronary Syndromes represents a major update to how clinicians diagnose and treat acute coronary syndromes, unifying previous STEMI and NSTEMI guideline documents into a single comprehensive evidence-based resource.  1. Unified ACS Guideline (STEMI + NSTEMI + UA) The 2025 guideline consolidates separate STEMI and NSTEMI guidance from 2013 and 2014 into one framework covering all presentations of ACS — unstable angina (UA), non-ST-elevation ACS (NSTE-ACS), and ST-elevation myocardial infarction (STEMI).  2. Early Evaluation and Initial Management Rapid assessment remains paramount: Immediate ECG and clinical risk stratification for patients with suspected ACS. Early initiation of appropriate antithrombotic therapy unless contraindicated.  3. Antiplatelet and Antithrombotic Therapy (DAPT) Dual antiplatelet therapy ...