摘要:

This study was designed to examine the relationship between epicardial ST change (EpST) and regional myocardial blood flow (RMBF) following coronary occlusion and extent of myocardial infarction (MI) in awake dogs. Fifteen min and two hr after coronary occlusion simultaneous measurements of EpST and RMBF were made. Six days later histologic MI and RMBF were determined in transmural myocardial samples from each electrode site. Greatest ST elevation occurred at sites of greatest ischemia and MI. However, 15 min after occlusion 29% of sites with greater than 50% MI and 39% of sites with greater than 50% reduction in RMBF did not demonstrate ST elevation greater than 2 mV. There were poor correlations between EpST and MI (r= 0.59) and RMBF (r= 0.57). Comparable relationships were observed two hr after occlusion. In the present study, there were not close quantitative or qualitative relationships between EpST and MI or RMBF. A good correlation was observed between RMBF at two hr and MI (r= 0.89).

ISSN:0009-7322    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

To determine whether multiple lead precordial electrocardiographic recordings offer an improved index for noninvasive estimation of left ventricular hemodynamic function and segmental dyssynergy, precordial mapping was performed in patients with anterior myocardial infarction, and the number of pathologic Q waves (.0.04 sec) was counted (Q-Index). Left ventricular function was determined by cardiac catheterization and angiography and correlated with the Q-Index. The Q-Index correlated well with dyssynergy extent (r= 0.84) and inversely with ejection fraction (r= −0.87), stroke work index (r= −0.79) and cardiac index (r= −0.66). Three patient groups were defined by Q-Index: group I, 0.04 sec Q complexes < 15; group II, 15-25; group III, 26-35. QIndex related closely to functional classification and survival (mean follow-up 12.2 months): group 1, 91%; group 11, 81%; group 111, 40%. Thus 35-lead precordial Q wave mapping with determination of total number of pathologic Q waves permits practical, atraumatic assessment of hemodynamic and functional status and allows prediction of survival in acute and chronic anterior myocardial infarction.

ISSN:0009-7322    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

Late hospital phase ventricular arrhythmias in acute myocardial infarction (MI) have been associated with a high incidence of sudden death following hospital discharge. Thirty-eight patients were studied 10-24 days following onset of symptoms of MI. Each patient had a 24-hour ambulatory ECG tape recording and left ventricular and coronary angiography performed. Patients with complicated ventricular arrhythmias (multiform, coupled, R on T VPCs or ventricular tachycardia), when compared to those with uncomplicated ventricular arrhythmias (unifocal or no VPCs), had a greater number of proximally narrowed major coronary arteries (P< 0.001), a higher coronary “score" (P< 0.001), a greater incidence of previous myocardial infarction (P< 0.005), a greater percentage of abnormal left ventricular segments 86% vs 69% (P< 0.001) and lower ejection fractions. These data suggest that late hospital phase survivors of Ml with complicated ventricular arrhythmias have more extensive coronary artery disease with greater left ventricular dysfunction than survivors with uncomplicated ventricular arrhythmias. This more extensive disease may result in increased areas of ischemic myocardium and may help explain the refrac' toriness of these arrhythmias to pharmacologic therapy.

ISSN:0009-7322    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

The anterior septal coronary artery was acutely ligated in 16 open-chest anesthetized dogs to produce an infarct of the septal myocardium. Twenty-four hours following occlusion complete epicardial mapping and extensive plunge electrode recording techniques were used to localize the sites of origin and patterns of activation of the ventricular tachyarrhythmias that developed during recovery. The earliest electrical activity for 13 individual rhythms was recorded from surviving septal subendocardial Purkinje fibers at the margins of the infarct, in the right or left ventricle, directly underlying the sites of earliest epicardial breakthrough. The sites of origin were verified by demonstrating unchanged activation sequences during pacing through the electrode sites which recorded the earliest ac- tivity. None of the arrhythmias arose from the His bundle or bundle branches despite the fact that these tissues course directly through the necrotic septum. The data presented supports the hypothesis that ventricular arrhythmias occurring in the 24-36 hour post acute infarction period may originate in the surviving subendocardial Purkinje system. Our experimental model shows that in cases in which a malignant rhythm arises from a focus, whether it is due to enhanced automaticity or local re-entry, epicardial mapping alone may not identify the source of the arrhythmias. Extensive endocardial mapping may provide a more rational basis for surgical interventions designed to abolish these arrhythmias.

ISSN:0009-7322    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

Ischemic myocardial injury has been detected recently in isolated perfused hearts and intact experimental animals with positron-emitting “C-paImitate and reconstructive tomography providing cross-sectional images of the heart free from superimposed activity in overlying structures. To evaluate the applicability of positron emission transaxial tomography in detecting infarction in man, 10 normal human subjects and 12 patients who sustained documented acute myocardial infarction three to 12 months previously were studied. Tomograms were obtained after intravenous injection of 5 to 10 mCi of “C-labeled palmitate, a physiological substrate of myocardium. Tomograms from all normal subjects ex- hibited homogeneous distribution of “IC-palmitate throughout each 1.5 cm thick cross section of the ventricle. Tomograms from all patients with remote anterior or inferior and posterior myocardial infarction exhibited diminished accumulation of “IC-palmitate delineating regions corresponding to the electrocardiographic locus of infarction. The distribution of “IC-palmitate detectable by positron emission transaxial tomography in a series of cross sections from apex to base in the same normal subject or patient with remote myocardial infarction was analogous to that observed in normal dogs and animals with experimentally induced myocardial infarction.

ISSN:0009-7322    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

The ability to quantitate the amount of permanent left ventricular dysfunction in patients with unstable ischemic heart disease would have important clinical value. Left ventricular function curves were constructed in sixteen patients with acute myocardial infarctions and five patients with unstable angina pectoris syndrome at an average of 56 hours (±8) after the onset of symptoms. Fifty ml increments of low molecular weight dextran were rapidly infused into the right atrium during constant monitoring of the pulmonary artery end-diastolic pressure (PAEDP) via a Swan-Ganz thermodilution catheter. An average of 400 ml (range 200-800) was infused to produce a significant change in the PAEDP (range 3-13 mm Hg). The cardiac index was measured before and after the dextran infusion. The slope of the left ventricular function curve was calculated by dividing the change in the cardiac index by the change in the PAEDP. The sixteen patients with acute myocardial infarction underwent left heart catheterization and left ventricular biplane angiography an average of six months later. The five patients with unstable angina pectoris were studied within one month. The slope value of the left ventricular function curve was compared to angiographic ejection fraction by linear regression analysis and the correlation coefficient was 0.80. These data demonstrate 1) the slope of the left ventricular function curve in patients with acute myocardial infarction or unstable angina correlates well with the angiographically calculated ejection fraction; 2) as early as two days post myocardial infarction, the residual impairment of left ventricular function can be estimated.

ISSN:0009-7322    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

The effect of global ischemia of different degrees of severity and reperfusion was studied in the isolated working rat heart. Four degrees of ischemia were induced by reducing the control total coronary flow of 8 ml/min to 0, 0.04, 0.4, or 0.8 ml/min for 30 minutes, after which the coronary flow was returned to the control level. After severe ischemia (0 and 0.04 ml/min ischemic coronary flow groups), recovery of contractility was to less than 30% of the control, pre-ischemic value of ventricular developed pressure and dP/dt, and irreversible cardiac contracture and an increised pacing threshold occurred. After moderate ischemia (0.4 and 0.8 ml/min ischemic coronary flow groups), contractile function recovered com- pletely, ischemic contracture was rapidly reversible and the pacing threshold did not increase. The moderately ischemic groups were able to function at a stable, low level of contractility for the 30 minute ischemic period, whereas the severely ischemic groups had no contractile activity. The amount of calculated tissue lactate accumulation correlated with the occurrence of irreversible ischemic injury; the severely ischemic groups which failed to recover with reperfusion accumulated 3-5 times as much lactate as the moderately ischemic groups which recovered completely. The results suggest that relatively small differences in the severity of the ischemic condition can markedly affect the degree of tissue injury.

ISSN:0009-7322    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

The purpose of this study was to determine whether propranolol, which has been shown to reduce the extent of myocardial infarction, reduces microvascular injury which may play a role in exacerbating ischemia. Saline (10 dogs) or propranolol (2 mg/kg i.v., 7 dogs) was injected prior to a one hour occlusion of the left anterior descending coronary artery. Carbon black (1 ml/kg), which labels damaged and leaky vessels, was injected 5 min after release of the occlusion and allowed to circulate for two hours. By morphometric analysis of 1 A thick sections, 75 i 12% of vessels and 84 ± 7% of myocardial cells showed damage in untreated dogs; only 2 ± 1% of vessels and 9 ± 8% of myocardial cells showed damage in the propranolol-treated dogs (P< 0.001). The number of carbon black-labeled vessels/10 fields/biopsy from comparable areas of ischemic tissue was 55 ± 7 in untreated dogs and 27 ± 3 in propranolol-treated dogs (P< 0.001). The results suggest that propranolol not only protects the ischemic myocardial cell, but also significantly decreases the ischemic microvascular changes.

ISSN:0009-7322    

出版商:OVID    

年代:1977

数据来源: OVID

ISSN:0009-7322    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

The hemodynamic benefits of combining administration of dopamine with nitroprusside (NP) were evaluated in nine patients with chronic congestive heart failure due to ischemic, idiopathic myocardial or valvular cardiac disease. NP alone (68 μg/min) produced decline in left ventricular end-diastolic pressure (LVEDP) from 25.4 to 14.1 mm Hg (P< 0.01) but modest increase in cardiac index (CI) from 2.41 to 3.02 L/min/m2 (P< 0.05). Dopamine alone (6 μg/kg/min) caused an elevation of CI to 3.36 (P< 0.01) but without decrease of LVEDP. Simultaneous infusion of the two agents resulted in favorable alterations in both hemodynamic variables: LVEDP decreased to 15.7 (P< 0.01) and CI increased to 3.52 (P< 0.01). It is concluded that dopamine substantially enhances the effectiveness of nitroprusside therapy in congestive heart failure by providing concomitantly the principal beneficial actions of the vasodilator and dopamine used separately. Thus combined dopamine with NP treatment considerably raises low CI while markedly reducing elevated LVEDP and provides a potentially efficacious pharmacologic modality for the treatment of severe congestive heart failure due to left ventricular dysfunction.

ISSN:0009-7322    

出版商:OVID    

年代:1977

数据来源: OVID