Left ventriculometry: the Minnesota experience with a bioengineering approach

Left ventriculography is used by cardiologists, surgeons, and pharmacologists. Cardiologists use it to assess ventricular function and to scan the results of longitudinal studies to follow the course of the patient. Surgeons employ the results to appreciate changes following surgery, as improvement postbypass, and to compare the effectiveness of alternative procedures or maneuvers. Pharmacologists examine the results to assess the consequences of drug administration. In patients with ischemic heart disease, left ventriculography is an indispensable adjunct to selective coronary arteriography, and it provides anatomic and functional information important for diagnosis and for predicting the outcome of the patient. Using the results from cine left ventriculography, it is possible to calculate the EDV, ESV, SV, and EF and thus to evaluate the pump function of the left ventricle objectively, quantitatively, and reproducibly. However, these measures indicate total left ventricular function. A more detailed analysis of the cine left ventriculogram can provide specific information about the impaired segments. Methods for measuring and calculating the volume changes of the entire left ventricle were described and illustrated with their clinical implementation. Five methods of determining regional myocardial wall motion were applied to a population of subjects with normal wall motion and to patients with abnormal wall motion. The method was chosen which agreed best with the visual assessment of the cine by experienced cardiovascular radiologists. Clinical applications of regional wall motion assessment were described. A computer-compatible data base was created for roentgen images of a normally and of an abnormally contracting left ventricle, and this data base was contributed to a national repository for computer-compatible data bases. An automatic pattern recognition method was used to determine whether regional wall motion was normal or abnormal, and it was able to distinguish between these two groups satisfactorily. Current trends in ventriculography were described. A bioengineering approach has been used to solve the problem of measuring and describing the wall motion of the left ventricle of the human heart. The approach has been applied to the analysis of the contraction of the whole ventricle, regional wall motion, and the temporal pattern of wall motion. The mathematical equations underlying the analysis have been given, explained, and illustrated with examples. The implementation of the analyses using computers was discussed. The assumptions and sources of error have received particular attention.