Detection of residual myocardial function in acute transmural infarction using postextrasystolic potentiation. A computerized angiographic study

Twelve subjects without clinical or hemodynamic heart failure, admitted for a first untreated anterior transmural myocardial infarction, were evaluated within the first 24 hours after the onset of symptoms. Pulmonary angiography was performed while a right ventricular extrastimulus was delivered every fourth beat at 50% of the RR interval to systematically analyze the basal and the postextrasystolic left ventricular frames. Left ventriculograms were quantitatively processed to determine the ejection fraction (EF) and the percentage of the end-diastolic circumference showing hypokinetic (%HK) or akinetic (%AK) areas. Left ventricular angiography was performed 1 month later in all cases at the same paced atrial heart rate to compare this final angiogram to the basal and the electrically induced postextrasystolic initial beats. During the 1-month period of the study none of these subjects had complications such as recurrent chest pain, heart failure or rhythm disturbances, and no drug administration was necessary. Comparing the basal cycle of the initial angiogram and the final cycle, a poor correlation was found between the corresponding values of EF (r = 0.34), %HK (r = 0.38) and %AK (r = 0.48). The correlations were much better when a comparison was made between the postextrasystolic cycle of the initial angiogram and the final cycle (EF, r = 0.84; %HK, r = 0.96; %AK, r = 0.95). These results indicate that, from the first day after a TMI, the analysis of the postextrasystolic frame allows accurate estimation of the final left ventricular function and regional wall motion abnormalities. Postextrasystolic potentiation may be useful in the acute state of transmural infarction to discriminate potentially reversible ischemic from definitely jeopardized areas.

Relationships between hemodynamic profiles and topography of acute myocardial infarction

Initial hemodynamics were studied in 101 patients with acute myocardial infarction complicated by shock or left heart failure. 59 had anterior myocardial infarction (AMI); 42 had inferior myocardial infarction (IMI). Data were processed by univariate analysis and correspondence analysis. AMIs and IMIs were significantly different on conduction disturbances, heart rate, left ventricular filling pressure, mean pulmonary artery pressure and right ventricular function indices. Both patients and parameters were projected on the most meaningful factorial plane generated by correspondence analysis. This two-dimensional graphical representation showed that all the information was roughly distributed along the 2 orthogonal axes defining this plane. Survivors and nonsurvivors were fairly well separated along the first factorial axis (prognostic axis) which was highly correlated with both outcome and left ventricular function parameters. AMIs and IMIs were grossly separated along the second factorial axis (topographical axis) which was rather well correlated with location and right ventricular function parameters. These studies suggest that AMI and IMI hemodynamic profiles are modulated by the presence or absence of right ventricular dysfunction. Moreover right ventricular dysfunction may be held responsible of some lack of information about left ventricular function status.

[A system of computer pre-treatment of electrocardiographic data]

A system of analogue pretreatment aimed at analysis of the arrhythmias in real time is presented. It is based on the separate detection of the P wave and the QRS complex, and on the use of a bipolar electrically conducting catheter introduced into the auricle of the right atrium. Such an arrangement is relatively insensitive to adventitous activity, both in the high and low frequency range, and provides on four separate channels impulses representing the P wave, the QRS complex, wide QRS complexes and premature QRS waves. In all cases, the atrial channel transmits all synchronised signals originating from atrial activity without any loss of information. This apparatus has been tried out with various arrhythmias and, if integrated, into a system of automatic detection, it should bring about a considerable saving in time and memory storage space.

A hardware device for recognition of P and QRS waves

A new hardware device has been constructed to detect QRS and P complexes for the purpose of automatic arrhythmia interpretation. This apparatus can operate in noisy conditions and provide synchronized pulses representative of P complex, QRS complex, wide QRS, and premature QRS to different output channels. P wave identification is achieved with a high degree of reliability through a specially designed bipolar electrode catheter. The device could minimize demands on central processor time and core storage computer.

A statistical prognostic study of pump failure in acute myocardial infarction

Repeated measurements of maemodynamic status were made and were subsequently subjected to analysis to assess prognosis in a group of patients with acute myocardial infarction and pump failure. Two multivariate methods were used: correspondence analysis and discriminant analysis. Both these methods agreed with the highest prognostic reliability of left ventricular function indices. Using various discriminant functions a prospective study was carried out on a test sample and a rate for well-classified subjects ranging from 80% to 90% was obtained. For each discriminant function the different causes of misclassification were analysed; among them a right ventricular dysfunction was allowed to account for discrepancies between expected and observed data on inferior infarction.