Incidence and significance of the low-voltage electrocardiogram in acute myocardial infarction.

In a retrospective study of 304 patients with acute transmural myocardial infarction admitted to the coronary care unit, 22 percent (67 patients) exhibited low voltage on their electrocardiograms within 72 hours of admission. The course of hospitalization of these patients was compared with an equal number of consecutive patients with transmural infarctions and normal electrocardiographic voltages. Among the patients with low voltage, there was a significantly higher incidence of previous infarction or present extensive infarction, congestive heart failure, and cardiogenic shock. This group of patients also demonstrated a markedly higher mortality. This study substantiates the clinical impression that acute myocardial infarction complicated by a low-voltage ECG implies a poor prognosis. It is speculated that this electrocardiographic pattern may reflect decreased ventricular performance as a result of widespread myocardial damage.

Hemodynamic correlates of the normal aortic valve echogram. A study of sound, flow, and motion.

The aortic valve echogram was recorded in open chest dogs simultaneously with aortic flow, acceleration of flow, aortic and left ventricular pressures, and intracardiac phonocardiograms. Comparison of echographic with hemodynamic data showed the following: The aortic valve started its opening with the onset of flow, at the same point that left ventricular pressure exceeded aortic pressure. Complete valve opening preceded peak aortic flow by an average of 43 msec and the cusps started to move toward closure while flow was still accelerating. Final closure of the valve was achieved at the time of zero flow and preceded the aortic second sound by 4-10 msec. The echographically determined "valve orifice area" correlated well with aortic stroke volume (r = 0.94). The intensity of the aortic first sound was related to peak acceleration of aortic flow. The intensity of the second sound was not related to the amplitude of cusp motion but correlated well with the aortic pressure at the time of closure and with peak flow deceleration.

Wenckebach A-V block: a frequent feature following heavy physical training.

Among 126 top Israeli athletes, in whom an ECG was obtained during a random survey, 11 had first-degree heart block (P-R greater than or equal 0.21 sec.) and in three of them Wenckebach's phenomenon was found. The latter could be demonstrated only after 15 minutes' rest in a recumbent position and was abolished by sitting, standing, and the administration of atropine. This subjects with Wenckebach's phenomenon were followed for 6 years. The heart block was found to be present only during seasons of intensive training and could not be demonstrated a few weeks after the training was reduced in intensity or stopped. No heart disease or diminution of performance developed during 6 years of follow-up. Transient second-degree heart block in top athletes is probably much more frequent than hitherto suspected, but it can be demonstrated only if the athlete is examined during rest and in the recumbent position. It is assumed to be a physiological phenomenon related to heavy physical training.