Heart rate less than 60 bpm. VPC. Incremental prolongation of PR interval with eventual failure to conduct P wave. Broad, notched QRS in leads I, aVL, V6, with associated T-wave inversion. Axis leftward of -30 degrees.
Sinus bradycardia with second-degree AV block, Mobitz type I. VPC. LBBB with associated ST-T-wave changes. Left-axis deviation.
Comment: Note in this example that the shortest PR interval of the Wenckebach sequence is prolonged beyond 0.2 s. However, first-degree AV block should not be diagnosed in the presence of a higher degree of AV block.
This patient also has complete LBBB. A major diagnostic criterion of LBBB is absence of the normal septal activation from left to right. In LBBB, the initial forces depolarize the septum from right to left, instead of the usual left to right. Accordingly, there cannot be septal Q waves in leftward leads. A Q wave may occasionally be seen in lead aVL, but should not appear in either lead I or leads V5–V6. In this example, one might initially consider a Q wave present in lead I, but on closer inspection, a small R wave is evident.
JL, Robles de Medina
et al: Criteria for intraventricular conduction disturbances and preexcitation. J Am Coll Cardiol
A 73-year-old asymptomatic man with a history of hypertension.
High J point with concave upward ST elevation leads I, II, aVL, aVF, V2–V6.
Sinus rhythm. Normal variant, isolated J-point elevation.
Comment: This tracing represents the normal variant of early repolarization seen in some healthy individuals. A large study of nearly 50,000 healthy Air Force personnel found that 2 percent had benign ST elevation similar to the type shown in this example. Normally, the ST segment is isoelectric with the T-P segment. ST elevation to a greater degree may represent early repolarization or acute pericarditis. Interestingly, 1 year later, this patient with early repolarization developed acute pericarditis with more profound ST-segment abnormalities (see next tracing).
et al: The early repolarization normal variant electrocardiogram: Correlates and consequences. Am J Med