The left ventricular isovolumic contraction time (IVCT) is divided by the mitral closure sound (MI) into two components: the initial phase of ventricular contraction, before the atrioventricular valves close (C-MI interval), and a second pre-ejection phase, between mitral closure and aortic opening (Mi-E interval There were 43 women and ii men. Ages ranged from I6 to 53 years, with an average of 33.5 years. Thirty-six patients had pure mitral stenosis (MS), I2 had predominant mitral stenosis (MSmr), 2 had mitral stenosis and regurgitation approximately of an equal degree (MSMR), and 4 had pure severe mitral regurgitation (MR). Among the patients with MS, 34 had severe MS (diameter of mitral orifice of 2 to IS mm), and 2 had milder MS (diameter of 20 mm). In 48 patients the diagnosis was confirmed by cardiac operation, and in 6 by right heart catheterization. Only 9 patients had received digitalis for a week before the study. There was a control group of 40 normal subjects, 20 women and 20 men. Their ages ranged from i6 to 52 years, with a mean age of 29 years.The left ventricular apex cardiogram, the phonocardiogram, and the right extemal carotid tracing were recorded simultaneously with the patient lying in the left lateral decubitus position in apnoea at the end of a normal expiration. Pulse wave (linear) condenser microphones (BouckeBrecht) for recording apex cardiograms and carotid tracings, and a crystal microphone for recording phonocardiograms were used, connected to a direct-writing multichannel recorder Hellige (Model 9400/6). The records were taken at a paper speed of 5o mm per second.The following time intervals were measured ( Fig. I): isovolumic contraction time (IVCT) or C-E interval, from the onset of the systolic wave (C point) on the apex cardiogram to the carotid upstroke minus the delay time of the carotid pulse wave (calculated ejection point or E point)
1) By the use of polygraphic tracing including apex cardiogram, phonocardiogram and indirect carotid tracing, an almost full and precise phasic analysis of the cardiac cycle may be obtained.(2) New methods for the measurement of the ejection period and mechanical systole are presented. Additional Indexing Words: Isovolumic contraction time Initial phase of ventricular contraction Pressure elevation time Ejection period Mechanical systole Protodiastole Isovolumic relaxation time Rapid ventricular filling Slow ventricular filling Active ventricular filling T HE phases of the cardiac cycle and their relationships have been increasingly used in modern cardiology. Cardiac catheterization is not applicable to the measurement of the phases of the cardiac cycle in everyday medical practice.Indirect methods are mainly used for this purpose. But the usual polygraphic tracing including electrocardiogram, phonocardiogram and indirect carotid tracing is not sufficient in this respect. If the apex cardiogram is included and simultaneously recorded with the above mentioned curves, an almost full phasic analysis of the cardiac cycle may be obtained.As is known the apex cardiogram is reliable in timing left-sided events in the cardiac cycle9) which was confirmed by correlating the low-frequency apical vibrations of the apex cardiogram with hemodynamic events within the left heart.10),20)
MATERIAL AND METHODSForty normal subjects (19 women and 21 men) were studied. They ranged in age from 14 to 54 years (average age 28 years). Lead II of the electrocardiogram (ECG), an indirect carotid tracing (CT) from the right carotid artery, a left ventricular apex cardiogram (ACG) and a medium frequency phonocardiogram (PCG) were recorded simultaneously with the person reclining in the left lateral decubitus in apnea at the end of a normal expiration. The identification of the origin of the ACG (left or right apex beat) was based on the configuration of the QRS complex
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