ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

The effects of intraaortic balloon counterpulsation (IABC) on the magnitude and severity of myocardial ischemic injury were studied in 19 dogs following acute coronary occlusion and in two patients with cardiogenic shock. In the experimental group, epicardial electrocardiograms were taken from 10-14 sites on the anterior surface of the left ventricle following occlusion of the left anterior descending coronary artery or its apical branch. The average S-T-segment elevation ([see Equation in PDF File]) was used as an index of the magnitude of myocardial ischemic injury. In six dogs, two successive 20-min occlusions were performed, and IABC was started prior to the second occlusion. [see Equation in PDF File] 15 min following occlusion decreased from 3.3 ± 0.9 mv after the control occlusion to 1.4 ± 0.4 mv (P< 0.01) after the occlusion with IABC. In three dogs in which the occlusion was maintained and IABC initiated 30 min later, [see Equation in PDF File] decreased from 1.2 to 0.6 mv. In six dogs in which IABC was started 3 hours after occlusion, it induced a reduction of [see Equation in PDF File] from 4.2 ± 1.1 to 2.8 ± 1.0 mv (P< 0.01). In four dogs, ischemic injury was augmented by isoproterenol infusion (0.25 μg/kg/min), and while continuing the infusion IABC was initiated. It reduced [see Equation in PDF File] from 8.0 ± 1.9 to 5.7 ± 1.8 mv (P< 0.05). Thus, IABC reduced the magnitude and extent of myocardial ischemic injury after experimental coronary occlusion, both when IABC was employed prior to, and 3 hours following, coronary occlusion. IABC was also effective in reducing myocardial ischemic injury which had been increased by isoproterenol infusion. Employing a noninvasive technic, which utilizes 35 electrodes on the thorax, the effects of IABC were examined in two patients with cardiogenic shock associated with acute myocardial infarction. Preliminary observations in these patients confirmed the experimental results indicating that IABC reduced myocardial ischemic injury.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

The effects of glucose-insulin-potassium (GIK) infusion and glucose (G) infusion started 30 min after experimental coronary occlusion and the combination of GIK and propranolol (P) started 3 hours after coronary occlusion on the development of myocardial infarction were studied in 37 dogs. Fifteen minutes after the coronary occlusion, epicardial electrocardiograms were recorded at 10-15 sites; 24 hours later transmural specimens were obtained from the same sites for determination of myocardial creatine phosphokinase (CPK) activity and the evaluation of morphologic changes. In the control group (normal saline infusion) the relationship between S-T-segment elevation (mv) 15 min after occlusion and CPK activity (IU/mg of protein) 24 hours later was: log CPK = −0.064 S-T + 1.24; r = 0.81. In the GIK group, the infusion was begun 15 min following epicardial mapping, and sites with the same S-T-segment elevations showed less CPK depression than did the control group: log CPK = −0.022 S-T + 1.25. The G group also showed less CPK depletion than the control group but to a somewhat lesser extent than the GIK group (log CPK = −0.030 S-T + 1.20). The group receiving GIK and P 3 hours after occlusion also showed less CPK depression than did the control group (log CPK = −0.034 S-T + 1.26). Histologic analysis in 24-hour specimens showed that sites which exhibited S-T-segment elevation 15 min after occlusion showed normal histology in 3% of specimens obtained from control dogs, while the other 97% showed early signs of myocardial infarction. However, in the GIK group, 36% of the specimens with S-T-segment elevation prior to the infusion were histologically normal 24 hours later, while in the G group 30% were normal, and in the GIK and P group 17% were normal. Electron microscopy confirmed the morphologic changes observed by light microscopy. Thus, in the presence of experimental coronary occlusion, GIK exerts a protective effect against myocardial ischemia and reduces the extent of myocardial necrosis. G alone acts similarly but to a lesser degree, while a beneficial effect can also be demonstrated when GIK and P are started 3 hours after the onset of coronary occlusion.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

The pharmacokinetics of the relatively polar and rapidly acting cardiac glycoside ouabain (G-strophanthin) were studied in dogs and human subjects by the use of a newly devised radioimmunoassay technic. This method had high specificity and a sensitivity of less than 0.1 ng of ouabain per ml of plasma or urine. After administration of a single intravenous dose, the plasma ouabain concentration fell rapidly in both dogs and humans. After 7 hours, a phase of exponential decline was reached which had a half-life of 18 hours in dogs and 21 hours in normal human subjects. Repeated intravenous administration of ouabain to human subjects for 9 consecutive days resulted in the establishment of a plateau of plasma concentration and urinary excretion after 4-5 days, confirming plasma and urinary half-lives in the 19-24-hour range. The mean ratio of renal clearance of ouabain to that of creatinine was 0.81 in the human subjects. The plasma half-life of ouabain determined in these studies is in good agreement with previous observations of the half-life of dissipation of positive inotropy and of slowing of ventricular response to atrial fibrillation after ouabain administration.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

Cardiac catheterization studies were performed in eight patients 1 year after cardiac transplantation and in two of these again at 2 years. Intracardiac pressures at rest were normal in all patients, both 1 and 2 years postoperatively. Average cardiac index at rest at 1 year was 2.3 liters/min/m2and average heart rate was 90 beats/min. Responses to amyl nitrite, atropine, and tyramine failed to demonstrate efferent autonomic reinnervation of the donor hearts. Findings associated with a 10-min period of submaximal supine bicycle exercise 1 year after transplantation included: (1) a gradual rise in heart rate throughout most of the exercise period; (2) prompt elevation of left ventricular end-diastolic pressure by an average increment of 10 mm Hg, followed by a decrease during late exercise in some patients; (3) a progressive increase in LV systolic pressure throughout the first half of the exercise period; (4) a continuously positive change in LV rate of pressure change (dp/dt) throughout exercise; (5) an average 44% increase in stroke volume; and (6) an average 92% increase in cardiac output. The slope of the regression of cardiac output on oxygen uptake during exercise was within the range of normal. Cardiac output, however, was lower than normal both at rest and during exercise, and the arteriovenous oxygen diflerence was accordingly widened.In one patient studied 1 and 2 years after transplantation, hemodynamic findings were comparable on both occasions. In the other, however, the cardiac output response to exercise was distinctly diminished at 2 years as compared to 1 year, due almost entirely to failure of the stroke volume to increase. Coronary arteriography in this recipient revealed evidence of occlusive coronary disease compatible with graft atherosclerosis.These studies demonstrate the sustained capacity of the transplanted human heart to support normal physical activity late in the postoperative period. Although utilizing atypical adaptive mechanisms characteristic of the denervated heart, the transplanted heart responds in a directionally appropriate manner to the metabolic demands of exercise.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

In order to study left ventricular performance and motion under ischemic stress, incremental atrial pacing was performed in 10 patients with angiographically proven coronary artery disease until angina pectoris or segmental S-T depression appeared. Single-plane left ventricular cineangiograms were obtained in both the resting and the transiently ischemic state induced by pacing.Abnormal motion appeared with pacing in two of three patients with normal contraction at rest; in one of them, gross dyskinesis of the cardiac apex was noted. Seven patients had abnormal contraction at rest; six showed an increase in either the severity or the topographic distribution of abnormality, while one showed no change.Left ventricular end-diastolic pressure and cardiac index were not altered significantly despite changes in the pattern of contraction. Left ventricular end-diastolic volume decreased irrespective of the development of asynergy, but ejection fraction decreased markedly in those patients in whom asynergy was induced de novo or increased.Thus left ventriculography during pacing-induced ischemia may reveal segmental or generalized abnormalities of contraction not necessarily reflected in the usual hemodynamic parameters of function. Moreover, asynergy induced by pacing is associated with a decreased ejection fraction.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

Rosen KM, et al: Circulation 45: 965, 1972. On pages 970 and 971, figures 4 and 5 are reversed.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

In order to correlate the electrical and mechanical events occurring in atrial flutter, three patients have been studied using the standard electrocardiogram, a computer-processed vectorcardiogram, and reflected ultrasound recordings of valvular motion. Anterior motion of the mitral valve leaflet occurs in the region of the nadir of the atrial flutter wave in lead II of the electrocardiogram. In one patient in whom it was possible to obtain a tricuspid leaflet echocardiogram, anterior motion was also initiated close to the nadir of the flutter wave. The probable sequence of electrical and mechanical events in atrial flutter is discussed. In one patient with a prosthetic mitral valve, correlation of diastolic clicking sounds with respect to the poppet echocardiogram provided some insight into irregularities in timing of previously reported flutter sounds.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

Total atrioventricular bypass (Kent bundle) does not explain all the findings in some cases of Wolff-Parkinson-White (W-P-W) syndrome. Two cases are reported in which two accessory pathways, set in series or in parallel, could be demonstrated. In case 1, a short P-R interval, gap phenomenon, and presence of delta wave with either a short or long P-R interval suggested the hypothesis of an atrio-His accessory path (James fibers). The presence of a type-B delta wave during His stimulation demonstrated the takeoff of another bypass (Mahaim fibers) below or at the point of stimulation. The His-ventricle accessory path had a supernormal phase of conduction during either atrial or His stimulation. In case 2, the rapid spread of the impulse to the His bundle (P-H 65 msec) was responsible for a normal H-R interval (35 msec) during either reciprocating tachycardia or normal sinus rhythm wtih a nonwidened QRS and minimal W-P-W deformity (partial cancellation of the delta wave). During reciprocating tachycardia, alternatively short and long P′-H intervals with constant H-R (His bundle) and R-P′ (Kent bundle) were due to alternate antegrade atrio-His conduction through the atrionodal nodal bypass (James fibers) and the A-V node. Surgical findings confirmed the existence of a left bundle of Kent. The division of the His bundle resulted in a maximal W-P-W deformity (type A) and abolished the reciprocating tachycardia.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

Forty-four cases of myocardial infarction with cardiac rupture, 88 cases of unruptured myocardial infarction, and 88 cases without myocardial infarction were studied retrospectively. The incidence of cardiac rupture in cases with acute myocardial infarction alone was 5.5% while in hearts having both healed and acute myocardial infarction the incidence was 2.3%. One instance of cardiac rupture was encountered in a heart having only a healed myocardial infarction with subsequent aneurysmal dilation of the healed infarct. Although females represented only 37% of the population having acute myocardial infarction in this institution, they accounted for 55% of the cases of cardiac rupture. On the average the hearts which ruptured following myocardial infarction were lighter and thinner than in the control group of patients having infarction without rupture. Among the clinical correlates possibly associated with postinfarction rupture the most significant finding in the present study is the presence of postinfarction hypertension. In the group of cases with cardiac rupture this was present in 40% while in the control group not having suffered cardiac rupture the comparable figure was 14%. A history of diabetes was found in 18% of the cases of myocardial infarction not having suffered cardiac rupture. A similar history was found in only 9% of the cases having a postinfarction cardiac rupture. This latter incidence is identical with the frequency of diabetes mellitus in the general autopsy population. There is a suggestion that early and severe atherosclerosis may cause earlier heart disease and when infarction occurs provide some protection against rupture. Of interest among the 44 cases of cardiac rupture, none of the patients had cirrhosis, in striking contrast to the 11% incidence of this condition in our general autopsy population.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID