Left ventricular hypertrophy (LVH) is the abnormal enlargement of the left ventricle in response to increased peripheral vascular resistance, most commonly resulting from long-standing hypertension. The ventricle is forced to work against the increased pressure, causing the muscle to hypertrophy in an effort to keep up with the demand.
Symptoms LVH by itself has no individual symptoms. However, LVH often results in a drop in ejection fraction, which leads to such symptoms as dyspnea on exertion, orthopnea, and chest pain.
Etiology While the most common etiology of LVH is long-standing hypertension, there are other, less common causes. These include hypertrophic cardiomyopathy, athletic training, and aortic stenosis.
ECG findings As discussed in a previous installment of this department on axis deviation, left axis deviation can suggest the presence of LVH. The reason for this is that all cells in the heart muscle depolarize, generating electrical activity. More cells (eg, hypertrophy) create more electricity. This can cause a shift in the axis toward the hypertrophied chamber—in this case, the left ventricle.
Other ECG findings can also indicate LVH. Increased voltages generated by hypertrophied heart muscle are best observed in the R and S waves (Figure 1) of various leads overlying the left ventricle, specifically V1, aVL, V5, and V6. The R wave is the first upward deflection of the QRS complex and is measured from Q to R on the ECG. The S wave is the downward portion of the QRS complex after the R wave (R to S on the ECG).
Diagnosing LVH Many ECG criteria for LVH have been published over the years. All are quite specific (greater than 90%) but not very sensitive (6.9%).1-3 This means that patients whose ECG demonstrates findings that fulfill the criteria for LVH are likely to have clinical LVH; however, patients lacking the ECG criteria may still have clinical LVH. Sensitivity does improve with the combination of multiple sets of criteria.3 We chose to combine the Sokolow and Lyon criteria1 with the Cornell criteria.2
Sokolow and Lyon offer two criteria: First, the S wave measurement in lead V1 added to the R wave measurement in lead V5 or V6 (whichever is larger) must equal more than 35 mm. Second, the R wave in aVL must be greater than or equal to 11 mm. Cornell diagnoses LVH if the sum of the S wave in V3 and the R wave in aVL is greater than 28 mm in men or greater than 20 mm in women.
EKG challenge
A 70-year-old white man with a history of hypertension presented with complaints of fatigue and lower-extremity edema. At this visit, his BP was 148/92 mm Hg. He takes oral hydrochlorothiazide 20 mg each day and oral lisinopril 40 mg day.
Using the stepwise approach to analyze the patient's ECG (Figure 2), consider the following:
1. Is the ECG regular? Yes. The QRS complexes march out.
2. What is the heart rate? Find a QRS complex on or near a dark line.