摘要:

The natural history of contraction abnormalities and their response after acute myocardial infarction in man were studied using radionuclide angiography. Sixteen patients were studied before and after sublingual nitroglycerin within 24 hoers, 5–7 days and 4–6 weeks after the onset of chest pain. Within 24 hours, central chord shortening in the zone of infarction was reduced to 13.1 ± 9.8%, but improved to 27.2 ± 18.4% (p< 0.001) after nitroglycerin. After 5–7 days, central chord shortening improved similarly, but less markedly, from 12.9 ± 9.2% to 24.4 ± 13.2% (p< 0.001). After nitroglycerin 4–6 weeks after the acute myocardial infarction, the central chord showed no response to nitroglycerin; it was 13.9 ± 10.9% before and 13.4 ± 2.5% after nitroglycerin. Changes in the lateral chords paralleled changes in the central chords in the three studies. Nonischemic zone showed improvement after nitroglycerin In all three studies. Global ejection fraction improved and end-diastolic and end-systolic volumes decreased in all three studies after -nitroglycerin.These data indicate that after acute myocardial infarction, there is a significant reduction in hemiaxis shortening in the central and lateral chords that remains essentially unchanged over 4–6 weeks. However, the asynergic ischemic area improves considerably after nitroglycerin within 24 hours and 5–7 days, but fails to improve after 6 weeks.

ISSN:0009-7322    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

To study endocardial wall motion and thickness as indexes of infarction, we used two-dimensional echocardiography to examine regional percentages of systolic wall thickening (%Th) and endocardial motion (%EM) in infarcted canine hearts. Thirteen dogs were studied 48 hours after occlusion of the circumflex or left anterior descending coronary artery. Two-dimensional echocardiographic cross sections obtained every 16 msec at 1-cm intervals from apex to base in an open-chest, anesthetized preparation were analyzed with a computer-aided contouring system for quantification of segmental %EM and %Th at 16 equally spaced points per slice. Slices corresponding to each two-dimensional echocardiographic cross section were examined pathologically for evidence of infarction.Comparing histologically infarcted with distant normal zones in each slice, %Th and %EM both yielded clear separation with little overlap (−12.5% infarcted vs 37.4% normal for thickness; −11.3 vs 25.7% for motion,p≪ 0.001 for both). Endocardial motion was less precise than thickening, however, in distinguishing infarct from either distant normal zones or zones directly adjacent to infarct.Although wall thickening was useful in separating out true subendocardial infarct, change in systolic thickening was not accurate in detecting the transmural extent of infarction. In 827 individual two-dimensional echocardiographic segments with varying degrees of transmural involvement, segments with 1–20% extent of transmural infarction showed reduced thickening compared with noninfarcted segments (39.9 vs 15.2%,p< 0.001), whereas myocardial segments with 21–100% transmural infarction showed systolic thinning (−8.9 to − 13.3%). There was no significant augmentation in the severity of systolic thinning as the extent of transmural infarction increased from 21% to 100%.We conclude that: (1) Wall motion abnormalities are less precise than thickening in discriminating between infarcted and noninfarcted zones and could lead to overestimation of infarct size. (2) There is an abrupt deterioration in systolic thickening in segments containing more than 20% transmural extent of infarction. (3) There is no significant augmentation in the degree of systolic thinning as the transmural extent of infarct increases from 21% to 100%. This "threshold" phenomenon may therefore preclude accurate estimation of infarct size by two-dimensional echocardiography. (4) Evidence of any systolic thickening indicates less than 20% transmural extent of infarction.

ISSN:0009-7322    

出版商:OVID    

年代:1981

数据来源: OVID

ISSN:0009-7322    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

Different approaches to the quantification of regional left ventricular (LV) function from twodimensional echocardiographic (2-D echo) images were assessed for their ability to optimize interobserver reproducibility in a heterogeneous patient population and to minimize the variability of regional function observed in a homogeneous normal population. Area, hemiaxis and perimeter measurements were examined, as were the effect of the degree of image subdivision into halves, quadrants or octants. Each approach was also tested using both a fixed and a floating frame of reference for the definition of a regional-axis system. The area method was consistently superior to either linear method in optimizing both reproducibility and variability. Reproducibility decreased inversely with the degree of subdivision. The axis-system frame of reference had no effect on reproducibility. The floating-axis system yielded the same variability as the fixed system for shortaxis sections at the mitral valve level, but slightly less variability for a papillary muscle level section. We conclude that area-based methods are superior for the evaluation of regional LV function with 2-D echo, but the degree of subdivision of the image and the frame of reference chosen do not greatly affect reproducibility or variability and should be chosen based on their performance in a well-defined clinical population.

ISSN:0009-7322    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

The quantitative approaches to the assessment of regional left ventricular (LV) function described in the preceding paper were applied in a well-defined population of patients with coronary artery disease. Two groups were chosen by electrocardiographic and angiographic criteria: group 1 had infarction and regional wall motion abnormalities and group 2 had no infarction and normal wall motion. Sensitivity to detect wall motion defects, specificity to correctly categorize normal segments, and overall predictive accuracy were evaluated for each two-dimensional echocardiographic approach. In addition, the ability of each method to localize regional contraction defects properly was evaluated. Area methods yielded better predictive accuracy than linear methods (87–95% vs 76–84%). No significant differences in accuracy were noted between quadrant and octant approaches. The fixed external-axis system was superior to a floating one for localizing contraction defects. We conclude that an area-based method, using a fixed-axis system and either octant or quadrant image subdivision, provides the best combination of predictive accuracy in categorizing LV segments as normal or abnormal and the greatest ability to localize LV regional abnormalities.

ISSN:0009-7322    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

Electrophysiologic studies were carried out in 85 patients with serious ventricular arrhythmias: 44 with recurrent sustained ventricular tachycardia (group A), 16 with recurrent nonsustained ventricular tachycardia (group B), and 25 with recent prehospital ventricular fibrillation not associated with acute myocardial infarction (group C). Programmed ventricular stimulation from the right ventricular apex included premature stimulation during normal sinus rhythm, atrial pacing, and ventricular pacing, as well as brief bursts of rapid ventricular pacing (RVP). A repetitive ventricular response (RVR) was defined as one or more nonstimulated premature ventricular depolarizations in response to a single paced premature ventricular depolarization during normal sinus rhythm or atrial pacing. RVRs were observed in seven of 44 (16%) group A patients, one of 16 (6%) group B patients, and three of 25 (12%) group C patients. In contrast, single and double premature ventricular stimuli during ventricular pacing and/or bursts of RVP resulted in the reproducible initiation of ventricular tachycardia in 40 of 44 (91%) group A patients, 10 of 16 (63%) group B patients, and 19 of 25 (76%) group C patients. We conclude that RVRs to single ventricular extrastimuli during normal sinus rhythm or atrial pacing are rare, and therefore are an insensitive index of susceptibility to serious ventricular arrhythmias in these patients.

ISSN:0009-7322    

出版商:OVID    

年代:1981

数据来源: OVID

ISSN:0009-7322    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

The importance of the site of stimulation to the initiation of sustained ventricular tachyarrhythmias was determined in 24 adult mongrel dogs. Studies were performed 3–30 days after two-stage occlusion of the mid- or distal left anterior descending coronary artery, modified by a reperfusion stage. Unipolar cathodal stimuli of twice-threshold intensity and 2 msec duration were introduced at five to 24 sites in each dog in the distribution of occluded and nonoccluded vessels. Strength-interval curves were constructed from 232 measurements at these sites and local properties of excitability and refractoriness were correlated with the ability to initiate arrhythmias. All dogs had sustained ventricular tachyarrhythmias inducible from at least one site. Intramyocardial sites with normal excitability and refractoriness within 2 cm of an area of infarction were most often successful (27 of 44, 61%) in the initiation of sustained arrhythmias. Less successful sites included normal left ventricular plunge electrode sites > 2 cm from an area of infarction (eight of 32, 25%) (p= 0.002), left ventricular plunge electrode sites within an area of infarction (20 of 103, 19%) (p< 0.001), normal right ventricular sites (five of 24, 21%) (p< 0.001), and endocardial catheter sites (six of 29, 21%), (p< 0.001). These findings suggest that local properties of excitability and refractoriness at the site of stimulation, as well as anatomic and geometric factors, may be critical in the initiation of sustained ventricular tachyarrhythmias using the technique of programmed electrical stimulation.

ISSN:0009-7322    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

A randomized trial of surgical vs nonsurgical management was carried out in men 60 years of age or younger who had recovered from a recurrent myocardial infarction. Of 205 patients considered, 100 had few or no symptoms and had coronary vessels favorable for bypass grafting; these patients fulfilled the trial conditions and were randomized (50 surgical and 50 nonsurgical). In 41 patients (elective nonsurgical group), randomization was not considered justifiable because of relatively unfavorable coronary anatomy or severe left ventricular dysfunction. Nineteen patients had elective surgery because of disabling angina despite full medical treatment or because of significant left main coronary stenosis. In 45 patients, coronary angiography was not undertaken because of medical contraindications or reluctance of the patient to enter the study.Actuarial survival curves (mean follow-up 4.5 years) show an annual mortality rate of 3–4% per year for all investigated patients, and no advantage for the randomized surgical over the randomized nonsurgical group. The results suggest that in the absence of disabling angina or left main coronary artery stenosis, coronary artery surgery need not be advised for survivors of recurrent infarctions who have severe coronary artery disease. Moreover, the prognosis for the group of patients not treated surgically appears to be better than has been previously described.

ISSN:0009-7322    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

Fifteen institutions participating in the Collaborative Study in Coronary Artery Surgery (CASS) have performed isolated coronary artery bypass surgery upon 6630 patients (1061 women and 5569 men) for coronary artery disease. The overall operative mortality (OM) was 2.3% (range 0.3–6.4%). Mortality increased with age, from 0 in the group 20–29 years old to 7.9% In the group 70 years and older. OM was higher for women in each age group, ranging from 2.8% for ages 30–39 years to 12.3% for age 70 years and older (0.8% and 5.8% for men). Clinical manifestations of congestive heart failure were associated with increased OM. Mortality was 1.4% in one-vessel, 2.1% in two-vessel and 2.8% in three-vessel disease (diameter narrowing ⩾ 70%). Among 1019 patients with left main coronary artery (LMCA) stenosis, OM ranged from 1.6% in patients with mild stenosis and a right-dominant system to 25% in patients with severe (⩾ 90%) stenosis and left dominance. OM varied with ejection fraction (EF) (1.9% for EF ⩾ 50% to 6.7% for EF < 19%) and left ventricular wall motion score (1.7% for least abnormal to 9.1% for most abnormal). For elective surgery, OM was 1.7%, for urgent surgery 3.5%, and for emergency surgery 10.8%. Mortality was 40.0% among 30 patients with severe LMCA stenosis who underwent emergency revascularization. Advanced age, female sex, symptoms of heart failure, LMCA stenosis, impaired left ventricular function and nonelective surgery are associated with a higher OM. These factors should be considered in the selection of patients for coronary artery surgery.

ISSN:0009-7322    

出版商:OVID    

年代:1981

数据来源: OVID