Determination of left ventricular wall thickness by angiocardiography.

Abstract Measurements of the change in left ventricular wall thickness from diastole to systole, by a variety of methods and in different species, indicate unacceptable discrepancies (range 15 to 100 per cent). Since angiocardiographic methods are accepted more and more in the study of human heart disease, the accuracy of this type of wall thickness measurement was investigated in 31 patients with representative examples of a variety of cardiac disorders with and without hypertrophy. A method was developed permitting the prediction of wall thickness on any film taken during the cardiac cycle. End-diastolic muscle mass was considered the most accurate and its volume was assumed not to change during systole. Comparison of predicted and observed values for wall thickness showed complete agreement in 10 of the 31 patients. Average wall thickness increased 39.8 per cent. This result is in complete agreement with those reproted by Mitchell and associates 5 in dogs in whom implanted radiopaque markers permitted accurate measurement of wall thickness during systole. In 10 of the remaining 21 patients the predicted wall thickness could subsequently be recognized during a careful re-examination of the films. In the remainder, there was no way in which the true left ventricular wall could be recognized and wall thickness increased an average of 92.5 per cent. Similar figures have been reported by others. 3,13 It is concluded, that direct measurement of wall thickness during the second phase of ejection (after 200 msec. after onset of contraction) will lead to large errors, particularly in patients with hypertrophy. As a first approximation to a solution for this problem, a computational method is described, which showed complete agreement between observed and predicted values in all cases during the first 200 msec. after the onset of contraction.