Assessment of left ventricular function by synchronous echocardiography and apex cardiography.

The relationship between left ventricular dimension measured using M-mode echocardiography and simultaneous apex cardiography has been studied in 69 normal subjects (2 groups) and 159 patients with heart disease (6 groups). A loop was formed by plotting the apex cardiogram, which is related to ventricular wall stress, against ventricular dimension. Abnormalities in ventricular function due to shape or volume changes in the isovolumic phases of the cardiac cycle produced characteristic alterations in the loop pattern. These changes were measured and the results for different groups compared. Normal subjects were divided into two age groups (13-38, 40-78) and no significant differences were found between them. In the heart-disease, patients, 25% had an abnormal decrease in dimension during isovolumic contraction and 25% had an abnormal increase during isovolumic relaxation. When the downstroke of the apex cardiogram was differentially analysed, it was possible to show that 60% of heart-disease patients lay outside the normal range. By using these techniques it is possible (a) to show abnormal ventricular response to pressure changes during the isovolumic periods, (b) to quantify the abnormality and, (c) to detect early abnormal muscle behaviour before it becomes visible on conventional ultrasound recordings.