Final answer:
A 20-mm S wave in lead V1 and a 25-mm R wave in lead V6 on an ECG indicate (B) left ventricular hypertrophy. This assessment is based on the increased voltage observed from the left ventricle, which is a common manifestation of LVH and requires clinical experience for accurate interpretation.
Step-by-step explanation:
The finding of a 20-mm S wave in lead V1 and a 25-mm R wave in lead V6 on a patient's 12-lead electrocardiogram (ECG) suggests left ventricular hypertrophy (LVH). These measurements indicate an increased voltage from the left ventricle, which is a common sign of LVH. The presence of LVH is oftentimes associated with hypertension or aortic stenosis but can also be caused by a variety of cardiomyopathies.
When analyzing an ECG, the size of the waves is significant. In general, an S wave deeper than 20 mm in V1 or an R wave higher than 25 mm in V6 are key indicators for left ventricular hypertrophy, according to commonly used criteria like the Sokolow-Lyon index. It's important to note that while ECG is a valuable tool for cardiac assessment, the full interpretation is complex and usually requires considerable experience and clinical correlation.