Dr. Usman's Cardiology Notes

  🫀 Long QT Syndrome (LQTS) — A Complete, Clinically Focused Guide Long QT Syndrome (LQTS) is an inherited or acquired cardiac channelopathy characterized by delayed myocardial repolarization, manifesting as QT interval prolongation on ECG and predisposing to life-threatening arrhythmias like Torsades de Pointes. Understanding the genetic subtype, typical triggers, and ECG signature helps guide diagnosis, counseling, and risk-stratification. Here is a clinical deep dive based on the three major genotypes. --- 🔹 LQTS Type I (LQT1) Gene: KCNQ1 Mutation Type: Loss of function Ion Channel: Slow delayed rectifier potassium current (IKs) 🧠 Pathophysiology KCNQ1 mutations impair outward K⁺ flow during repolarization → prolonged action potential and delayed relaxation, especially during sympathetic surge. ⚡ Typical Triggers Physical exertion, especially swimming Emotional stress Sudden adrenergic activation Swimming is the most classic trigger due to cold-shock and sympathetic surge—LQT...

Differentiating LBBB-Pattern SVT From VT Using Initial Forces in Lead V1 Based on the classic Kindwall Criteria (Kindwall et al., Circulation 1988) Distinguishing supraventricular tachycardia (SVT) with left bundle branch block (LBBB) from ventricular tachycardia (VT) is often challenging because both can produce a broad-complex tachycardia with LBBB morphology. Kindwall and colleagues (1988) published a landmark analysis identifying initial QRS forces in V1 as a powerful discriminator. This article explains the why and how of these ECG clues. --- Background: Why V1 Initial Forces Matter In true LBBB, ventricular activation starts normally in the right ventricle (RV) and then spreads slowly to the left ventricle (LV). Thus, the initial portion of the QRS reflects rapid septal activation, which remains normal even if the overall QRS is wide. In contrast, VT originating from the LV produces abnormal early activation, with slow cell-to-cell conduction from the ectopic focus → leading to s...

❤️ Revised Cardiac Risk Index (RCRI): Parameters, Scoring, and Clinical Interpretation The Revised Cardiac Risk Index (RCRI) is one of the most widely used and validated tools to estimate a patient's risk of major cardiac complications before undergoing non-cardiac surgery. It helps clinicians stratify patients into risk categories and guides decision-making about further testing, optimization, and postoperative monitoring. --- 🧩 Why RCRI Matters Major perioperative cardiac events—such as myocardial infarction, pulmonary edema, or cardiac arrest—carry high morbidity and mortality. RCRI provides a simple, bedside method using six clinical predictors to estimate this risk. --- 🔢 RCRI Components (1 Point Each) A total of six variables make up the RCRI. Each variable scores 1 point, making the maximum possible score 6. 1. High-Risk Surgery These include: Intraperitoneal surgery Intrathoracic surgery Suprainguinal vascular surgery (e.g., aortic, limb bypass above inguinal ligament) Th...

  ⚡ Negative HV Interval in EP Study: Understanding the Differentials A negative HV interval during an electrophysiology (EP) study is an unusual and clinically important finding. In a normal heart, the His-Purkinje system conducts impulses from the His bundle → ventricles, producing a positive HV interval (typically 35–55 ms). When the HV interval becomes negative, it means the ventricular electrogram precedes the His bundle signal, suggesting ventricular activation is occurring outside the normal His–Purkinje sequence. This phenomenon strongly indicates the presence of pre-excitation, accessory pathways, or non-physiological retrograde activation patterns. Correct interpretation is crucial because it helps identify arrhythmia mechanisms, particularly in wide-complex tachycardias. --- 🔍 What Is a Negative HV Interval? Normal: His deflection → ventricular activation (HV positive). Negative HV: Ventricular activation occurs before His activation. This indicates that ventricular act...

Basic Arrythmogenesis - Board Review Lecture

Contraindications of Digoxin Absolute Contraindications : ❶ Ventricular fibrillation ❷ Digoxin hypersensitivity Relative Contraindications : ① Acute MI ② Myocarditis ③ HOCM ④ Sick sinus syndrome ⑤ AV block (2nd- or 3rd-degree) without a pacemaker ⑥ WPW syndrome with AF Drug Interactions that Can Function as Contraindications : ☒ Amiodarone ☒ Dronedarone ☒ Verapamil ☒ Macrolides (e.g., clarithromycin) ☒ Itraconazole Conditions that Increase Risk of Digoxin Toxicity : ➠ Renal impairment ➠ Hyperthyroidism or Hypothyroidism ➠ Elderly or low body mass ➠ Electrolyte disturbances :  ➜ Hypokalemia  ➜ Hypomagnesemia  ➜ Hypercalcemia For more infographics keep visiting: drmusmanjaved.com Contraindications of Digoxin – A Detailed Clinical Guide Digoxin is one of the oldest and most widely used cardiac medications, particularly in patients with atrial fibrillation and heart failure with reduced ejection fraction (HFrEF) whose primary problem is symptomatic congestion despite optimal therapy. Altho...

  “Silent Threat: When Coronary Anomalies Turn Deadly — Understanding the Risk of SCD from Weird Heart Arteries” 🫀 What are anomalous coronaries? In a typical heart, coronary arteries arise from specific sinuses of the aorta and follow predictable courses. But in some people, there’s a congenital variation — a so-called Anomalous aortic origin of a coronary artery (AAOCA), or other Coronary artery anomalies (CAA). In AAOCA, a coronary artery arises from the “wrong” sinus of Valsalva. That misplacement often forces the artery to take a dangerous path — sometimes between the aorta and the pulmonary artery, or within the aortic wall (“intramural”).  Many of these anomalies remain silent and undetected for years. Indeed, population studies estimate CAA incidence between roughly 0.2 % and 1.2 %.  --- Why anomalous coronaries can cause Sudden Cardiac Death (SCD) 🔹 High-risk anatomy Not every coronary anomaly causes trouble — but certain “high-risk” variants do. Key danger fea...