Ischemic Patterns
Ischemic Patterns Coronary Anatomy The right and left main coronary arteries arise from the right and left aortic sinuses located at the aortic root. The left main coronary artery branches…
Paced Rhythms
Paced Rhythms The Pacemaker FIGURE 13.1 A. Anatomy of a dual-chamber pacemaker. B. ECG appearance of atrial and ventricular pacing. Electrode Types Unipolar Cathode is on the lead tip; anode…
Fast and Wide
Fast and Wide Wide Complex Tachycardia—Overview Both supraventricular and ventricular mechanisms underlie wide complex rhythms. Monomorphic Ventricular Tachycardia—Causes Monomorphic VT—ECG Features There are several features that may help diagnose monomorphic…
Fast and Narrow
Fast and Narrow Mechanisms Underlying Supraventricular Tachyarrhythmias Reentry Reentry occurs when the refractory periods and conduction speeds of two separate pathways differ. The initial impulse (marked by blue star) is…
QT Abnormalities and Electrolyte Disturbances
QT Abnormalities and Electrolyte Disturbances The QT Interval The QT interval represents ventricular depolarization and repolarization (phase 0-3 of the action potential, Fig. 8.1). The length of the QT interval…
Voltage Abnormalities
Voltage Abnormalities The Low-Voltage ECG Criteria Voltage is considered low in the limb leads when the average QRS amplitude is less than 5 mm and low in the precordial leads…
Abnormal T Waves
Abnormal T Waves The Normal T Wave The T wave represents rapid repolarization (phase 3 of the action potential). The normal T wave is asymmetric with a gradual slope followed…
Abnormal QRS Morphology
Abnormal QRS Morphology Brugada Pattern and Syndrome Pathogenesis Brugada syndrome is an autosomally dominant inherited disease (with incomplete penetrance) known for causing sudden death in patients with structurally normal hearts….
AV Conduction Blocks
AV Conduction Blocks First-Degree AV Block First-degree AV block is a delay in conduction, not a true block. First-degree block represents conduction delay somewhere between the sinus node and ventricles….
Premature Beats
Premature Beats Premature Atrial Complex Premature atrial complexes (PACs) arise from an ectopic focus anywhere in the atria, including the coronary sinus and pulmonary veins. Most often, PACs are asymptomatic…
