ISSN:0009-7322    

出版商:OVID    

年代:1973

数据来源: OVID

ISSN:0009-7322    

出版商:OVID    

年代:1973

数据来源: OVID

ISSN:0009-7322    

出版商:OVID    

年代:1973

数据来源: OVID

摘要:

Regional myocardial perfusion rates were estimated in ten patients with a residual transmural anterior wall infarction and ten patients with a residual transmural inferior infarction. The results in these two groups of patients were compared to the regional myocardial perfusion patterns obtained in 25 patients with normal coronary arteriograms who failed to demonstrate any electrocardiographic evidence of a myocardial infarction. Clearance rates of xenon-133 from multiple areas of the heart were monitored externally with a multiple-crystal scintillation camera following selective injection of the isotope into either coronary artery. Local myocardial blood flow rates were calculated by the Kety formula.In patients with normal coronary arteriograms, mean myocardial perfusion rates in the left ventricle (62 ml/l00g/min) exceeded flow rates in the right ventricle and atrium. There was slight inhomogeneity of local perfusion rates but no significant differences among major subregions (anterior descending, diagonal, or circumflex) within the left ventricle.In the group with an anterior transmural infarction, myocardial blood flow rates were significantly depressed (44 ml/l00g/min) and asynergy was present in the region of the left ventricle supplied by the anterior descending artery, which was >80% narrowed. Diminished capillary blood flow was found in the right ventricular region in the patients with an inferior transmural infarction and right coronary artery narrowing of >80%. There was no evidence of nutrient flow to the inferior surface of the left ventricle after right coronary133Xe injection.The data indicate that myocardial perfusion was reduced in regions of the heart which correspond to the electrocardiographic and angiographic location of residual transmural infarction. The perfusion rates observed in areas showing electrocardiographic evidence of transmural infarction and regional ventricular asynergy, although subnormal, were surprisingly high and suggested the presence of residual viable myocardial cells.

ISSN:0009-7322    

出版商:OVID    

年代:1973

数据来源: OVID

摘要:

In ten healthy, asymptomatic men, intra-arterial pressure and electrocardiograms were recorded during various types of exercise. Potential subendocardial blood flow was estimated from a diastolic pressure time index (DPTI) and myocardial oxygen requirements estimated from the tension time index (TTI). The ratio DPTI/TTI provided an estimate of the supply/demand relationship With sudden vigorous exercise without warm-up, the DPTI/TTI was below 0.35 in three men who had ischemic electrocardiograms, below 0.44 in three men with minor ST abnormalities, and above 0.44 in four men with normal ST segments. With a prior warm-up exercise, sudden exercise caused no ischemic changes, but DPTI/TTI was below 0.44 in two subjects who had minor ST abnormalities. Maximum treadmill testing produced higher heart rates and TTI than did sudden exercise, but DPTI/TTI was above 0.44 in all cases and no ST abnormalities occurred.Abnormal electrocardiographic responses produced by sudden, vigorous exercise in normal men may represent subendocardial ischemia caused by a transient, unfavorable alteration in the subendocardial oxygen supply/demand relationship which is predictable from arterial pressure measurements.

ISSN:0009-7322    

出版商:OVID    

年代:1973

数据来源: OVID

摘要:

Fourteen patients with a healed myocardial infarction (no angina pectoris) had maximal oxygen intake (VO2max) determinations and hemodynamic studies at submaximal and maximal exercise levels; seven patients were studied two months after an acute myocardial infarction (untrained group) while seven had followed a physical training program for 13.5 months (trained group). At the maximal exercise level, all patients exhibited a fall in stroke volume which was 15% (untrained group) and 18% (trained group) lower than at submaximal exercise level: this decrease in stroke volume, presumably resulting from myocardial ischemia, was the major factor limiting the Vo2max of the patients. The maximal arteriovenous oxygen (A-VO2) difference of untrained patients was the same (14.4 ml/100 ml) as for healthy subjects.Higher VO2max of trained patients (2.50 vs 2.07 liters/min) resulted almost exclusively from greater maximal A-VO2difference (16.5 vs 14.4 ml/100 ml); this suggests that long-term physical training increases peripheral extraction of oxygen by the working muscles.

ISSN:0009-7322    

出版商:OVID    

年代:1973

数据来源: OVID

摘要:

For a prospective study of risk factors for coronary heart disease (CHD), defined as acute nonfatal myocardial infarction and acute fatal CHD, 973 men, all aged 50 years, were recruited from a general Swedish urban population. Of the 855 who agreed to participate, 834 who showed no signs of CHD were selected and observed for nine years and four months. Autopsies were performed on all except two of the 55 patients who died during the study. Forty-four men developed clinical manifestations of CHD during this time; 19 of them died.Using a multiple logistic model, we analyzed nine probable risk factors. The presence of high serum cholesterol, smoking, high systolic blood pressure, dyspnea, and registration by the Temperance Board increased the risk of events related to CHD significantly. The presence of high serum triglycerides, high hematocrit readings, and increased geographic mobility did not cause a significant increase in events related to CHD. Those with sedentary jobs showed a slightly increased tendency to develop manifestations of the disease.The predictive power of the logistic function (with cholesterol, smoking, and systolic blood pressure) was tested in another randomly selected population sample of 5,146 men aged 51-55 years and found to be very accurate. The 10% (decile) of the population that had the highest risk of clinical manifestations of coronary disease and the 10% who had the lowest risk were defined. Manifestations of coronary disease occurred 29 times more frequently in the highest decile than in the lowest decile.

ISSN:0009-7322    

出版商:OVID    

年代:1973

数据来源: OVID

摘要:

Nine patients with coupled ventricular premature depolarizations (VPDs) were treated with intravenous procaine amide to abolish the arrhythmia. The effect of procaine amide on the electrocardiogram was carefully observed. Seven patients were treated with intermittent intravenous therapy-100 mg of procaine amide was injected every five minutes-and two were treated by constant intravenous infusion-200 &mgr;g/min/kg body weight; blood for plasma procaine amide concentration was obtained 4.5 to 5 min after each dose. As the cumulative dose of procaine amide increased, plasma drug concentration increased and the frequency of coupled VPDs progressively decreased. Moreover, in every patient an interesting electrocardiographic phenomenon was observed: as plasma drug concentration increased, the coupling interval progressively increased until the arrhythmia was completely abolished. A hypothesis for procaine amide's antiarrhythmic action is offered based on this new observation. This hypothesis suggests that procaine amide prolongs conduction in the depressed portion of a re-entrant pathway such that conduction is further delayed and block finally occurs, thereby terminating the arrhythmia.

ISSN:0009-7322    

出版商:OVID    

年代:1973

数据来源: OVID

摘要:

Eckberg DL et al.: Circulation47:1252, 1973. On page 1253, the formula should read[see Equation in PDF File]where P = intracavitary pressure in g/cm2, r1= internal left ventricular cavity radius, h = wall thickness at the minor left ventricular circumference, and L = long axis of the left ventricle.

ISSN:0009-7322    

出版商:OVID    

年代:1973

数据来源: OVID

摘要:

Bipolar potentials were recorded from intramural electrodes located within areas of acute myocardial ischemia in dogs. Alterations in bipolar potential electromotive force (EMF) and local activation times were measured at predetermined intervals up to 12 hours after coronary occlusion. Histochemical stains were used to correlate structural-biochemical changes with sites of electrophysiologic changes. In severely ischemic areas, bipolar potentials lost 50% of their preocclusion EMF within 30 min and 95% within six hours at which time all parameters stabilized. Lesser decreases in bipolar potential EMF were recorded in the peripheral areas of the infarct. Bipolar potential EMF increased at the junction of ischemic and normal myocardium. Activation time was delayed in ischemic areas but no correlation between the magnitude of delay and the degree of tissue ischemia could be established. Coronary reperfusion after 30 min, one hr, two hr and six hr of occlusion resulted in some return in bipolar potential EMF, decreasing as a function of duration between occlusion and reperfusion.Variation in the degree of ischemia of different zones of injury within an acute myocardial infarction, as well as a different response of those zones to the return of blood flow, was shown.

ISSN:0009-7322    

出版商:OVID    

年代:1973

数据来源: OVID