Case 10

ECG Description and Analysis

Please perform a systematic analysis of the 12-lead ECG.

1. QRS axis in the frontal plane?
2. Is the R wave height in the precordial leads normal?
3. What about the R/S ratio in the precordial leads?

The ECG is:

Let’s Analyze Case 10

What is the rhythm? A P wave precedes the QRS complexes with a constant and normal PR interval, and the P wave is positive in both I and aVF, indicating sinus rhythm with normal P wave axis.

In terms of frontal plane QRS axis, a predominantly positive QRS complex in II, III (with tallest R wave) and aVF, while aVR shows equal positive and negative amplitudes indicate that the axis is in the right inferior quadrant, or +120°.

The QRS duration is <120 ms. The ventricular activation time or R wave peak time in the right precordial leads is >30 ms. The QRS complex reveals a qR/qRs in V4R and V1. The presence of an initial q wave in V1 is indicative of supra-systemic right ventricular pressure overload.

The phenomenon is explained by the prominent right ventricle: the interventricular septum would be approximately parallel to the frontal plane, and the first vector (activation of the mid-septum), by the extreme rotation of the heart around the longitudinal axis, is now oriented to the left, producing a small initial q wave in V1 and tall R waves in V1-V3 (prominent anterior forces).

In addition, the R/S ratio in the precordial leads is positive in all leads, with no transition zone. There is ST depression, convex upward, followed by a negative T wave in II, III, aVF, and V1-V5 suggesting a right ventricular strain pattern. The QT interval is normal at 440 ms.

RVH type A: QRS loop with clockwise rotation and axis predominantly located in the anterior right quadrant. Typical of RVH in congenital heart disease with severe right ventricular pressure overload.

RVH type B: QRS loop with counter-clockwise rotation predominantly located in the anterior right or left quadrant. Typical of moderately severe RVH.

RVH type C: Typical of emphysema. QRS loop with counter-clockwise rotation predominantly located in the right posterior quadrant.

Exercise Based on Case 10

1. Learn the main principles of determining the QRS axis in the frontal plane.
2. Determine the transition zone and analyze the R/S ratio in the precordial leads.

What’s Your Diagnosis?

There are several ECG signs of RVH: QRS axis deviation to the right inferior quadrant, qR/qRs in V4R and V1, RV1 > RV6, SI-QIII-TIII (McGinn-White pattern), RaVR >4 mm.
Septal electrical activation is reversed, and RV “strain” and ST depression with inverted T waves in the inferior and right precordial leads.
Pressure (systolic) overload with type A RVH caused by severe dome-shaped pulmonary valve stenosis and gradient of 85 mm Hg was diagnosed.

ECG signs of right ventricular hypertrophy are important to recognize to optimize therapy and follow-up of the various causative diseases.