摘要:

The effects of postextrasystolic potentiation (PESP) on the contractile performance of central ischemic and border zones, as well as of nonischemic myocardium, were studied in 14 open-chest dogs subjected to a 4-hour left anterior descending coronary artery ligation followed by 1 hour of reperfusion. Intrinsic mechanical function during right ventricular pacing (134 4 3 beats/min) was compared with function in beats after single, closely coupled (179 i 3 msec) extrasystoles throughout ischemia and reperfusion. Regional myocardial blood flow using radioactive microspheres and infarct size using tetrazolium blue staining were also measured in these segments. PESP was capable of augmenting border zone segment performance to control levels throughout 4 hours of ischemia. PESP significantly augmented central ischemic zone segment function throughout ischemia, but not to control levels. After prolonged ischemia, reperfusion improved both regional intrinsic and potentiated mechanical performance in border and ischemic zones. At 4 hours of ischemia, myocardial blood flow decreased 52% (to 60 ml/100 g/min) in the border zone and 78% (to 28 ml/100 g/min) in the ischemic zone. Infarct size (the percentage necrosis of the transmural segment) measured 55 ± 10% and 74 ± 7% in border and ischemic zones, respectively.Thus, in the open-chest dog, PESP elicited considerable contractile reserve in border and ischemic zones during prolonged ischemia, and despite profound ischemic injury, both intrinsic and potentiated mnechanical function in the ischemic zone could be improved after reperfusion.

ISSN:0009-7322    

出版商:OVID    

年代:1980

数据来源: OVID

ISSN:0009-7322    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

While spatial asynergy at end-systole has been well characterized in patients with coronary artery disease, assessment of regional asynchrony has been hampered by technical constraints. We developed a computer-assisted method for analyzing regional asynchrony from the equilibrium (ECG-gated) radionuclide ventriculogram. Twenty patients with normal contrast left ventriculograms (nine with a normal coronary arteriogram [group 1] and 11 with coronary artery disease [group 2]) and 20 patients with asynergy during contrast ventriculography (group 3) were studied. The earliest evidence of regional asynchrony occurred in early systole. Regional ejection fraction at one-third systole was 0.32 i 0.02 (mean + SEM) in group 1, 0.22 4 0.01 in group 2 (p< 0.001) and 0.12 ± 0.01 in asynergic regions in group 3 patients (p< 0.001). In group 3, severe forms of regional asynchrony appeared in both early systole and early diastole: five patients (25%) had early systolic paradox, 13 (65%) had regional prolongation of peak ejection fraction and 16 (80%) had reduced percent peak ejection fraction at global end-systole. It appears, therefore, that there is progressively increasing regional asynchrony in patients with increasing severity of coronary artery disease.

ISSN:0009-7322    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

To compare the discriminant ability of early systolic and holosystolic ejection phase indexes to detect abnormalities of left ventricular performance, the contrast ventriculograms of 20 control patients and 55 patients with coronary artery disease (at least 70% stenosis of one or more major coronary arteries) were analyzed. All subjects were studied to evaluate chest pain, and none was taking propranolol or antihypertensive drugs. Several ejection phase indexes were evaluated, using holosystole, the first third of systole and the first half of systole. In the patients with coronary disease, 14 (25%) had one-vessel disease, 13 (24%) had two-vessel disease and 28 (51%) had three-vessel disease. In general, the ejection fraction was more useful than indexes based on velocity of ejection. Ejection fraction was lower in the coronary patients than in normal subjects for holosystole (0.62 + 0.14 vs 0.70 ± 0.08,p< 0.01), for the first third of systole (0.20 ± 0.06 vs 0.36 ± 0.06,p< 0.001), and for the first half of systole (0.34 ± 0.09 vs 0.53 ± 0.10,p< 0.001). Fourteen patients with coronary artery disease (25%) had a depressed holosystolic ejection fraction, 36 (65%) had a depressed first-half ejection fraction and 52 (94%) had a depressed first-third ejection fraction. We conclude that early ejection phase indexes, particularly the first-third ejection fraction, are more useful than holosystolic indexes in identifying resting abnormalities of left ventricular function.

ISSN:0009-7322    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

Serial myocardial imaging after a single dose of thallium is often used in evaluating patients with coronary artery disease. Because the appearance of the image is related to myocardial thallium content, it is important to know if transient ischemia occurring after tracer administration will influence the rate of myocardial thallium clearance. To answer this question 13 mongrel dogs (eight study dogs and five controls) were studied as follows. The left anterior descending (LAD) coronary artery and the anterior interventricular vein (AIV) were isolated. A catheter was inserted in the AIV to collect venous blood draining from the myocardium in the LAD distribution. Next, a snare was positioned around the LAD proximal to the tip of the AIV catheter. Thallium was given intravenously and paired samples of arterial and AIV blood were obtained every 10 minutes for 1 hour to determine thallium activity and potassium and hydrogen ion concentration. The LAD was then occluded for 10 minutes and paired blood samples were obtained. Next, the snare was released and paired blood samples were obtained beginning 10 seconds, 4, 10 and 20 minutes after reperfusion. Regional myocardial blood flow at the time of thallium administration and during the coronary occlusion was determined by the microsphere technique. After 20 minutes of reperfusion, the dog was sacrificed. The hearts were sectioned and counted for thallium and microsphere activity. During the coronary occlusion, the rate of thallium clearance (μCi/min × 10–2) from myocardium drained by the AIV (−1.1 ± 0.3, mean ± SEM) was similar to the rate just before occlusion (−0.68 ± 0.21,p= NS), as well as to the rate during the first minute of reperfusion (−0.77 ± 0.55,p= NS). In contrast, compared with the rate (mEq/min × 10–3) just before occlusion (−0.55 ± 0.61) a significant (p< 0.001) increase in output of potassium (−7.15 ± 1.04) by myocardium in the AIV distribution was observed during the coronary occlusion. Likewise, hydrogen ion output (mEq/min × 10–11) also increased significantly (p< 0.05) during the occlusion (−12.26 + 0.94) compared with the rate just before occlusion (−6.98 ± 0.78). At postmortem examination the ratio of thallium activity in the ischemic zone to that of the normal zone (1.01 ± 0.01) did not differ significantly from the ratio of thallium activity of the LAD to that of the circumflex region (1.04 ± 0.05) in control dogs in which no occlusion was performed.We conclude that transient ischemia occurring after thallium administration does not influence the normal rate of thallium clearance from the myocardium and thus may not be detected on serial scans.

ISSN:0009-7322    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

The effects of intracoronary (IC) nitroglycerin (NTG) on left ventricular (LV) function were evaluated in 13 patients with significant coronary artery disease. LV cineangiograms were performed in the 40° right anterior oblique projection before and 2 minutes after 0.15 mg NTG was injected directly into the left main coronary artery, and angiographically derived volume and dimensional data were related to simultaneously measured high-fidelity pressures. The diameter of the proximal left anterior descending (LAD) coronary artery was measured from 3-mi injections of contrast material before and after drug administration, and hemodynamic measurements were made 1 and 2 minutes after IC NTG. There was a 22% increase in diameter of the LAD, a small (but significant) and transient rise in heart rate, a more sustained increase in maximal dP/dt and no change in LV end-diastolic pressure, LV systolic pressure or LV volumes. NTG produced no change in global systolic LV function, quantitated as ejection fraction and mean normalized systolic ejection rate, or in regional systolic LV function, measured as 1) shortening velocity and percentage shortening of basal, middle and apical transverse diameters, and 2) segmental ejection fraction. There was also no change in diastolic function evaluated in terms of 1) volume stiffness: slope k of the linear relation between logarithmic pressure and volume, and 2) muscle stiffness: slope ae of the linear relation between logarithmic wall stress and midwall circumference. LV geometry, assessed by ratios of basal, middle and apical transverse diameters to the long axis and slope and intercept of the linear relation between middle diameter/long-axis ratio and volume throughout diastole, likewise was not affected. These results with IC NTG contrast with the previously demonstrated significant effects of sublingual NTG on hemodynamics, systolic and diastolic LV function and LV geometry, and suggest that the major cardiac actions of the drug are indirect.

ISSN:0009-7322    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

Forty patients were treated for cardiogenic shock secondary to acute myocardial infarction. Twenty-one (group 1) were treated with intraaortic balloon counterpulsation and 19 (group 2) were treated with counterpulsation and coronary artery bypass grafting. The groups were similar in age, incidence of previous infarction, initial hemodynamics and coronary anatomy.The in-hospital mortality between group 1 (52.4%) and group 2 (42.1%) was not significantly different. The difference in long-term mortality between group I and group 2 was substantially different (71.4% vs 47.3%).The subset of group 2 (n = 12) that underwent reperfusion and counterpulsation within 16 hours from the onset of symptoms of infarction had a lower mortality (25.0%) than the subset (n = 7) that underwent operation more than 18 hours after the onset of symptoms (71.4%). The long-term mortality in the subset of group 2 patients operated on within 16 hours after the onset of infarction was significantly different from that in group 1 (25.0% vs 71.4%,p< 0.03). The data suggest that reperfusion with counterpulsation is more effective when carried out early. Patients who develop shock more than 18 hours after the onset of symptoms of infarction appear to benefit most if treated with counterpulsation alone.

ISSN:0009-7322    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

Cross-sectional echocardiography was used to study left ventricular wall motion in 44 patients with myocardial infarction, and the extent of observed asynergy was correlated with left ventricular function. Echocardiographic studies were performed in short and long axes of the ventricle and nine segments were identified for analysis. Wall motion in each segment was classified as normal, hyperkinetic, hypokinetic, akinetic or dyskinetic. Based on this analysis a wall motion index was derived as an overall assessment of left ventricular asynergy. Left ventricular function was measured by clinical and hemodynamic parameters to note the presence of pulmonary congestion or peripheral hypoperfusion or both.Segmental asynergy was detected in all patients with acute myocardial infarction. Patients with uncomplicated infarction had a wall motion index of 3.2 ± 2.4, which was significantly less than that in patients with pulmonary congestion (9.7 ± 3.1,p< 0.001) or with both pulmonary congestion and hypoperfusion (10.6 ± 4.8,p< 0.001).In nine patients with acute ventricular septal defect or acute mitral regurgitation, wall motion index was 6.7 ± 1.9, significantly less than with other complicated infarcts (p< 0.001) but greater than with uncomplicated infarcts (p< 0.005). Wall motion index also discriminated complicated from uncomplicated infarction when death was used as the end point.Cross-sectional echocardiography provides a method of measuring the extent of left ventricular asynergy during acute myocardial infarction that correlates well with hemodynamic parameters of left ventricular function.

ISSN:0009-7322    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

Cross-sectional echocardiography was used to quantify volume in 21 canine left ventrides that were fixed in formalin and immnersed in mineral oil. Area, length and diameter measurements were obtained from short and long-axis cross-sectional images of the left ventricle and volume was calculated by seven mathematic models. Calculated volume was then compared, by linear regression and percent error analyses, with fluid volume of the left ventricle, obtained by filling the chamber with a known amount of fluid. Volumes ranged from 13-146 ml. Mathematic models using short-axis area and long-axis length gave higher correlation coefficients (r= 0.982 andr= 0.969) and lower mean errors (10-20%) than standard formulas previously used with M-mode echo and angiography. Thus, short-axis area analysis with cross-sectional echocardiography is well-suited for quantifying left ventricular volumes in dogs.

ISSN:0009-7322    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

We evaluated the ratio of the right ventricular preejection period to the right ventricular ejection time (RVPEP/RVET) as a predictor of pulmonary hypertension in 16 children with ventricular septal defects (VSD) (group 1). The children ranged in age from 5 months to 18 years. The RVPEP/RVET was measured at the time of cardiac catheterization by M-mode echocardiography from the pulmonary valve echogram and from a simultaneously displayed pulmonary arterial pressure signal obtained with a microtip, manometric catheter. The RVPEP/RVET measured by both methods was comparable (r= 0.91). The RVPEP/RVET was compared with the pulmonary artery diastolic pressure (PADP) (r= 0.54). The RVPEP/RVET ratio correlated less well with the pulmonary arterial mean pressure and pulmonary vascular resistance.In a second group of 51 children with VSD, echocardiographic measurement of the right ventricular systolic time intervals was performed within 24 hours before cardiac catheterization. The same variables of pulmonary arterial pressure as for group 1 were compared with the RVPEP/RVET ratio, and the results were similar.These data indicate that, although there is a relationship between the RVPEP/RVET and pulmonary hypertension, the ratio alone is not accurate enough to avoid cardiac catheterization in patients considered at risk for pulmonary vascular disease.

ISSN:0009-7322    

出版商:OVID    

年代:1980

数据来源: OVID