Right Ventricular Hypertrophy

We turn our attention now to the right ventricle, where all of the same principles apply. A major difference, however, is that the right ventricle has a much smaller muscle mass to begin with than the left ventricle. Therefore, in order for the right ventricle to surpass the left ventricle in size and shift our vectors substantially to the right, it has to hypertrophy rather massively. This means that, again, our ECG criteria are not going to be very sensitive indicators of early RVH. This also accounts for the fact that full-blown RVH on an electrocardiogram is relatively rare, especially in adults.

In RVH, as the right ventricular muscle mass increases, the direction of our main vector of ventricular depolarization naturally shifts progressively toward the right. This produces a taller than normal R wave in the right-side precordial leads (V1 and V2). As you would guess, this also produces a fairly deep S wave in the left-side precordial leads (V5 and V6) (Figure 8.3).

In fact, the R wave in lead V1 actually becomes taller than the S wave is deep. If we divide the amplitude of the R wave in lead V1 by the amplitude of the S wave in V1, we normally get a number of <1.0. This is called the R-to-S ratio (Figure 8.4). In RVH, however, the R-to-S ratio becomes >1.0 because of the exceptionally tall R wave. In other words, the usual pattern of

Figure 8.3. Right ventricular hypertrophy, with a tall R wave in the right-sided precordial leads and a deep S in the left-sided precordial leads.

the R wave becoming progressively taller across the precordium from right to left is reversed.

You will recall that in RBBB, we see a similar pattern of a tall R wave in V1 and a deep S wave in V6 (see Figure 7.3). To avoid confusing RVH with RBBB, we must therefore insist that the QRS be of normal duration when diagnosing RVH. The QRS duration can be in the upper limits of normal, as in LVH, but it cannot be 0.10 s or greater. Nevertheless, a pattern of incomplete RBBB can sometimes be seen with RVH, but cannot be used to reliably diagnose RVH.

I i f

3 A




y s=


3/8 = .37 9/3 = 3.0 R/S RATIO Figure 8.4. Calculation of the R-to-S ratio in any lead,

Female Pattern Heart Disease
Figure 8.5. Fully developed RVH with a strain pattern in the leads that look at the right ventricle, namely the right-sided precordial leads.This tracing is from a 12-year-old female with congenital heart disease and a single right ventricle.

The fully developed strain pattern of RVH, like that of LVH, consists of an upwardly convex ST depression blending into an inverted T wave, but now is seen in the right precordial leads (V1 and V2), which, of course, look at the right ventricle (Figure 8.5). The strain pattern may also frequently be seen in those limb leads toward which the main vector of ventricular depolarization is headed (electrical axis). In RVH, this is frequently lead aVF or III because of RAD.

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