Relationship between changes in R wave voltage and cardiac volumes. A vectorcardiographic study during hemodialysis.

The effects of acute changes in cardiac volumes determined by hemodialysis on cardiac voltages were assessed in 18 chronically uremic patients by means of a vectorcardiographic and scalar Frank leads recording, immediately before, at the 90th and 180th minute, and immediately after hemodialysis. The following parameters were simultaneously monitored: body weight, systolic and diastolic blood pressure, heart rate, hematocrit and, in eight patients, echocardiographic systolic and diastolic diameters of the left ventricle. During hemodialysis all voltages considered except R wave in X lead increased significantly. They were inversely correlated with body weight, blood pressure, and systolic and diastolic diameters and directly with hematocrit (volemia-dependent parameters). The maximal vector on the left sagittal plane and the R wave amplitude in Z lead, representing left ventricular posterolateral wall activation, showed the greatest increase. When, at the end of hemodialysis, an amount of fluids ranging from 300 to 800 ml was restored, these cardiac voltages decreased paralleling the increase of left ventricular diameters. In conclusion, these results demonstrate that cardiac voltage and volumes are inversely related.