Dr. Usman's Cardiology Notes

The Schwartz Score for Long QT Interval is a standardized clinical tool used to assess the probability of Congenital Long QT Syndrome (LQTS) based on ECG parameters, symptoms, and family history. A score >3 is strongly suggestive of LQTS and typically prompts further evaluation, genetic testing, and management planning. THE SCHWARTZ SCORE – DETAILED EXPLANATION 1. QTc Duration QT prolongation is the most heavily weighted parameter because delayed ventricular repolarization predisposes patients to polymorphic ventricular tachycardia, particularly torsades de pointes. • QTc ≥ 480 ms → 3 points • QTc 460–469 ms → 2 points • QTc 450–459 ms (males) → 1 point 2. ECG Features • Torsades de pointes → 2 points • T-wave alternans → 1 point (marker of repolarization instability) • Notched T waves in ≥3 leads → 1 point (seen particularly in LQT2) • Low heart rate for age → 0.5 point 3. Clinical History • Syncope WITH stress/emotion/exercise → 2 points • Syncope WITHOUT stress → 1 point Syncope ...

  Mechanism for perceiving heart pain in T1-4 dermatomes Mechanism for perceiving heart pain in T1–T4 dermatomes Cardiac pain is perceived in the T1–T4 dermatomes because of shared neural pathways between the heart and the upper thoracic spinal cord segments. The heart is innervated primarily by sympathetic afferent fibers that travel alongside sympathetic efferents. These visceral afferents originate from nociceptors in the myocardium, pericardium, and coronary vessels, which respond to ischemia, chemical mediators, and mechanical stretching. The pain signals travel through the cardiac plexus and ascend via sympathetic cardiac nerves to reach the dorsal root ganglia of spinal segments T1–T4. These same segments also receive somatic sensory input from the skin and musculature of the upper chest, medial arm, and shoulder region. Within the dorsal horn, visceral and somatic afferent fibers converge on the same second-order neurons, a phenomenon known as convergence–projection. Becaus...

  Guidelines for Pacing in Sinus Node Dysfunction (SND): A Detailed Clinical Article Sinus node dysfunction (SND), often termed sick sinus syndrome, encompasses a spectrum of abnormalities involving impaired impulse generation or conduction from the sinus node. Because SND is highly prevalent in aging populations and often presents with subtle or intermittent symptoms, guideline-driven decision making for permanent pacing is critical. Below is a comprehensive, clinician-focused review synthesizing ACC/AHA/HRS and ESC pacing guidelines. --- 1. Overview of Sinus Node Dysfunction SND includes: Sinus bradycardia inappropriate for physiological demand Sinus pauses/arrest Sinoatrial exit block Tachy-brady syndrome (AF/flutter alternating with profound bradycardia) Chronotropic incompetence The hallmark of SND is symptomatic bradycardia, not merely a slow rate. Common symptoms: fatigue, exercise intolerance, dizziness, presyncope, syncope, palpitations (in tachy-brady syndrome), and cogni...

Vernakalant: Mechanism of Action and Clinical Applications in Atrial Fibrillation Vernakalant is a novel, atrial-selective antiarrhythmic agent used primarily for the rapid pharmacologic cardioversion of recent-onset atrial fibrillation (AF). Unlike traditional antiarrhythmics that exert broad effects on both atrial and ventricular myocardium, vernakalant demonstrates preferential affinity for ion channels expressed predominantly in the atria, resulting in potent anti-AF effects while minimizing ventricular proarrhythmia. --- 1. Electrophysiologic Rationale for Vernakalant Atrial fibrillation is sustained by: Rapid atrial triggers Reentrant wavelets in a substrate of reduced action potential duration High-frequency depolarizations that promote ion channel remodeling To effectively terminate AF without causing significant ventricular arrhythmias, a drug must exert rate-dependent, atrial-selective effects. Vernakalant meets these criteria due to its unique channel-blocking profile. --- 2...

  Managment of STEMI as per ACC/AHA guidelines

Treatment of Narrow Complex Tachycardia (e.g., SVT) During Pregnancy • Vagal manoeuvres ↓ • Adenosine ↓ • Beta-blocker or Verapamil If the patient is unstable → DC shock

Tei Index (Myocardial Performance Index) in Echocardiography The Tei index, also known as the Myocardial Performance Index (MPI), is a simple, reproducible echocardiographic parameter that integrates systolic and diastolic ventricular function into a single numerical value. It is widely used for both left and right ventricular functional assessment and is relatively independent of heart rate and ventricular geometry. --- What Is the Tei Index? The Tei index reflects global ventricular performance by combining time intervals from Doppler echocardiography. Formula: \text{Tei Index (MPI)} = \frac{\text{IVCT} + \text{IVRT}}{\text{ET}} Where: IVCT = Isovolumic contraction time IVRT = Isovolumic relaxation time ET = Ejection time A higher Tei index indicates worse ventricular function. --- How Is Tei Index Measured on Echocardiography? 1. Pulsed-Wave Doppler Method (Conventional) Place PW Doppler at mitral inflow (LV) or tricuspid inflow (RV) Measure interval ‘a’ = time from end of one inflo...