[Phonomecanography in recent myocardial infarction. Ventricular mechanic curve]

Repeated recordings were made of the apexcardiogram throughout the first month after myocardial infarction in 30 patients. The classical timed intervals of the systolic wave are open to some criticism. The systolic waveforms are important. In the majority of transmural anterior infarctions there is a rounded appearance to the beginning of the wave which seems to prolong the electromechanical latency, followed by a late systolic bulge, or a domed waveform. This signifies a non-contractile area, and not neccessarily an ectasia. The early diastolic "peaktrough" appearance, found very frequently wherever the necrosis is situated, is indicative of asynergic contraction of the left ventricle. All of the diastolic phases are altered, probably by increased parietal stiffness: the TRI is lengthened; the "F" wave is flattened (and often absent later on in the condition), its duration is shortened over the anterior positions, and it may contain a shallow dip if there is LVF; the stasis wave is very feeble; the "a" wave is large when the infarct is extensive, or when there is LVF, or when there is longstanding hypertension. Enlargement of the "a" wave is especially indicative of a lowering of the performance of the left ventricle.