The effect of diet on echocardiographic left ventricular dimensions in normal man

The effect of dietary sodium and potassium on echocardiographic left ventricular dimensions was studied in normal subjects. In 10 subjects, left ventricular end diastolic volume was found to be 18.8 greater, and systolic volume 17.1% higher with zoo mEq sodium diet than on a 1Omeq sodium diet (P less than 0.025). While receiving an ad libitum diet, the subjects were found to have an end diastolic volume of 107.9 +/- 6.4 ml SE and an end systolic volume of 45.2 +/- 2.7 ml SE. During sodium depletion, values fell to 101.3 +/- 5.7 ml SE and 38.6 +/- 2.9 ml SE, respectively, then on a high sodium diet rose to 120.3 +/- 7.0 ml SE and 45.2 +/- 2.7 ml SE, respectively. Heart rate fell during sodium repletion by 4.2% (P less than 0.05) while mean arterial blood pressure, cardiac output and peripheral vascular resistance did not change significantly. In contrast, seven subjects consuming a diet containing 25 and 200 mEq potassium in seqeucne, the sodium intake remaining constant, did not display significant changes in cardiac dimension, heart rate, blood pressure, cardiac output, or vascular resistance. It is concluded that dietary sodium significantly effects the size of a nonfailing left ventricle, an effect that must be considered when single or sequential echocardiograms are interpreted.