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Query: UMLS:C0002962 (angina)
 21,142 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Physiologic concepts relating to reperfusion of ischemic areas of myocardium may be applied both to acute coronary insuficiency, manifested by angina pectoris, and to restoration of coronary blood flow by coronary bypass procedures, currently employed both in acute myocardial infarction and in chronic myocardial ischemia for relief of angina pectoris. Of the information currently available from experimental studies, much may be applicable to the clinical situation. After acutr transient coronary occlusion mechanical and electrical properties of the ischemic area rapidly return to normal, but there is prolongation of tension development and occurrence of ventricular arrhythmias; implications of these phenomena for clinical coronary ischemia deserve exploration. Following more prolonged coronary ischemia, results of experimental reperfusion appear to be variable and, although restoration of function following several hours of ischemia is possible, certain deleterious effects are often observed in the form of myocardial edema and hemorrhage. Clinical use of bypass procedures in acute myocardial infarction suggests that results may be good, but that deleterious effects are occasionally observed; occurrence of the later requires definition and explanation. Restoration of myocardial blood flow in the presence of normal left ventricular function in chronic coronary artery disease, and failure to reverse functional abnormalities when left ventricular damage has already ensued in the clinical situation, appears to be well established; however, better methods to assess the potential for recovery of function following revascularization are needed in both acute and chronic coronary artery diseases. It is anticipated that more careful exploration of pathophysiology both in the catheterization laboratory and in the operating room may aid this process.
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PMID:Effect of reperfusion in acute ischemia and infarction. 115 38

Ergometric tests (ET) were used to study 900 patients undergoing surgical myocardial revascularisation during the period between January 1983 and December 1989. ET was carried out without medical therapy between the 30th and 35th day post surgery. The test was positive in 193 subjects (21%); in 42 of the latter (5% of the total and 229 of positive subjects) symptoms of effort angina were found to persist. ET was negative in 557 patients (62%); 150 subjects (17%), although not positive, did not attain a sufficient heart rate to enable a 100% negative diagnosis to be made. No major complication was observed. Maximal short-term ET is a reliable and safe test for checking the efficacy of myocardial revascularisation and to assess functional recovery. In view of the relatively high percentage of positive tests due to ischemia but with the complete absence of symptoms, the authors affirm that the mere onset of anginous symptoms alone cannot be considered indicative of the success of cardiosurgery.
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PMID:[The early ergometric test after myocardial revascularization]. 178 92

The effects of an intracoronary infusion of nicardipine (0.2 mg over 10 min) on myocardial substrate uptake and function were studied in 16 patients with coronary artery disease and angina pectoris. Silent ischaemia, demonstrated by myocardial lactate production, was induced twice by pacing below anginal threshold. Nicardipine or saline was randomly infused during the first or second pacing. During pacing with nicardipine, no systemic effect was noted but coronary sinus flow increased (+ 18%; P less than 0.015) and myocardial oxygen uptake decreased by 12% (P less than 0.025). Transcardiac lactate production did not improve (-8 to -10 mumol min-1; NS) but net lactate uptake, estimated from radiolabelled lactate uptake, tended to rise and the glutamine uptake increased from 1.8 to 5.5 mumol min-1 (P less than 0.04). During recovery after pacing, lactate production decreased faster and LV peak (+) dP/dt and relaxation rate were significantly better after nicardipine infusion than after saline. Thus, during silent ischaemia induced by an increased oxygen demand, intracoronary nicardipine did not prevent lactate release but allowed a faster metabolic and functional recovery. These beneficial effects of nicardipine could be explained by an improved myocardial perfusion or by an effect on intracellular calcium homeostasis.
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PMID:Effects of intracoronary infusion of nicardipine during silent ischaemia on myocardial metabolism and function. 324 46

The effects of the Ca++-antagonist verapamil on hemodynamic and regional myocardial functional parameters were studied in a canine model of exercise-induced myocardial dysfunction which mimics exercise-induced angina pectoris. Six dogs, trained to submit to five treadmill exercise cycles, each consisting of 4 min of running and 11 min of recovery, were chronically instrumented with a microtip manometer in the left ventricle, two pairs of crystals for sonomicrometry, a hydraulic occluder around the circumflex branch of the left coronary artery and arterial and venous catheters. Control experiments with coronary stenosis clarified the reproducibility of exercise-induced regional contractile dysfunction and recovery of function in the intervening resting periods. In each individual dog, the same degree of stenosis was used in the subsequent experiments with verapamil. After two control runs which exhibited regional contractile dysfunction of comparable magnitude, verapamil was administered intravenously at a dosage of 0.3 mg/kg over a period of 5 min. Verapamil induced an increase in heart rate at rest due to sympathetic counterregulation secondary to a reduction of systolic and diastolic blood pressure. The exercise-induced increases in heart rate and rate-pressure product were reduced after verapamil, but the exercise-induced increase in left ventricular dp/dtmax was not significantly diminished. The hemodynamic changes led to a marked improvement of regional function during exercise in the area perfused by the stenosed coronary artery. In a study using identical experimental conditions, the Ca++-antagonist bepridil at a dosage of 2 mg/kg/5 min abolished the exercise-induced regional contractile dysfunction to a similar extent as verapamil.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Verapamil abolishes exercise-induced regional contractile dysfunction in dogs. 336 78

The effects of the bradycardic agent UL-FS 49 on hemodynamic and segmental parameters were studied in a canine model of exercise-induced myocardial dysfunction which mimics exercise-induced angina pectoris. Ten dogs, trained to subunit to five treadmill exercise cycles consisting of 4 min of running and 11 min of recovery, were chronically instrumented with a microtip manometer in the left ventricle, two pairs of crystals for sonomicrometry, a hydraulic occluder around the circumflex branch of the left coronary artery and arterial and venous catheters. Control experiments with coronary stenosis clarified the reproducibility of exercise-induced regional contractile dysfunction and recovery of function in the intervening resting periods. In each individual dog, a similar degree of stenosis was used in the subsequent experiments with UL-FS 49. After two control runs, which exhibited regional contractile dysfunction of comparable magnitude, UL-FS 49 was administered intravenously at a dosage of 0.5 mg/kg/5 min (6 dogs) or 0.25 mg/kg/5 min (4 dogs). Both doses of UL-FS 49 markedly reduced heart rate without alteration of left ventricular positive dp/dtmax at rest and during exercise. A marked improvement of regional function in the area perfused by the stenosed coronary artery was also observed during exercise. This beneficial effect of selective bradycardia, here observed with UL-FS 49, remains to be confirmed in clinical trials.
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PMID:Effects of the bradycardic agent UL-FS 49 on exercise-induced regional contractile dysfunction in dogs. 355 12

The availability of mobile gamma cameras or the nearness of nuclear medicine devices to the coronary care unit make the assessment of transient myocardial ischemia by radioisotopic techniques practical. Nuclear cardiology provides information on the presence, site and extent of ischemia and helps the clinician in the evaluation of myocardial functional impairment and recovery. Monitoring of myocardial wall motion by radionuclide ventriculography demonstrates that during angina at rest; global ejection fraction is not always sensitive to regional ischemia; episodes of angina with undetectable electrocardiographic signs of ischemia can be associated with severe myocardial dysfunction; separate left and right phase analysis of radionuclide ventriculography is a sensitive tool to assess segmental dyssynergy localized to the left or the right ventricle; a prevalent right ventricular impairment during ischemia, not measurable by Thallium scintigraphy, is possible; the recovery of function after ischemia is usually fast and apparently complete. In addition, useful diagnostic information can be derived by left ventricular injection of radioactive microspheres during cardiac catheterization followed by gated acquisitions of the intramyocardial radioactivity. Gated microsphere acquisitions, providing diastolic and systolic images, avoid blurring of images due to cardiac motion and enhance contrast between myocardium and background: the overall result is an improved detection and definition of small perfusion defects. Furthermore, this technique permits simultaneous assessment of regional perfusion and wall motion. An appraisal of potential mismatches between flow and function after revascularization procedures can be recognized by this approach. The development of technology is improving the performance of nuclear medicine instrumentation, hampered, at present, by limited spatial and temporal resolution.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Clinical application of monitoring techniques: radioisotopic methods. 375 80

To identify preoperative indicators of outcome following surgery for postinfarction left ventricular aneurysm, the authors have analysed the clinical course of 67 consecutive patients who underwent operation from 1970 to 1982. Follow-up extended to 12 years (mean 4.6 years) and was 97% complete. Postoperative mortality was 8.9%. Factors that were associated with a significantly (p less than 0.05) increased risk of early death included emergency surgery, the presence of ventricular arrhythmias preoperatively and a left ventricular end-diastolic pressure of more than 25 mm Hg on cardiac catheterization. Patients who underwent myocardial revascularization concomitantly had a lower mortality (7.1% v. 18.2% for aneurysmectomy alone), decreased postoperative morbidity and increased longevity. Marked functional improvement was noted in all groups. Actuarial survival (including operative mortality) was 66% at 6 years, and was significantly (p less than 0.05) better in patients operated upon for angina (83.6% +/- 8.1%) than in those operated upon for congestive heart failure (53% +/- 13%). The authors conclude that the most important predictor of outcome following postinfarction aneurysm surgery is the preoperative hemodynamic status of the left ventricle. Since functional recovery and prognosis after operation have been excellent, an aggressive surgical approach to symptomatic left ventricular aneurysms is warranted.
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PMID:Surgery for postinfarction left ventricular aneurysm: prognosis and long-term follow-up. 660 99

At medium term, the results of delayed angioplasty (DA) following intravenous thrombolysis (IVT) in terms of arterial permeability but particularly of left ventricular function (LVF) is still poorly understood and is the subject of this prospective study. Over 18 months, 76 patients underwent DA for the residual stenosis on day 8 +/- 5 with complete and partial success rates of 88.2% and 11.8% respectively. Rapid reocclusion (< 48 hours) was documented in 9.2% of cases. After 6 months, there had been no deaths and no recurrence of infarction but a recurrence of angina in 23.7% of cases. Angiographic monitoring, carried out in 56 cases (73.7%) after 6 +/- 2.4 months identified 21 restenosis (37.5%) and 6 re-occlusions (10.7%). 12 of the restenosis were successfully re-dilated. The effect on LV function was investigated in 50 patients. In the absence of reocclusion, the ejection fraction and the kinetics of the infarcted territory were improved; significant restenosis (> 60% by digital densitometry) did not appear to offset these improvements. In addition to the maintenance of arterial permeability, the possibility of functional recovery appears to be conditioned by the degree of contractile abnormality observed during the initial ventriculography. Despite the absence of restenosis after 6 months, the occurrence on day 6 of akinesia or above all of dyskinesia reduces the chances of contractile improvement with as a corollary more marked LV changes.
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PMID:[Delayed angioplasty for residual stenosis following thrombolyzed infarction: arterial permeability and left ventricular function after 6 months]. 836 95

Direct clinical evidence for the classical preconditioning phenomenon, with infarct size limitation as an endpoint, cannot be obtained. However, a number of patient groups have been identified in which adaptation to ischaemia has been demonstrated by enhanced recovery of function or preservation of high energy phosphates in models of repeated ischaemia, such as atrial pacing stress tests, percutaneous transluminal coronary angioplasty and aortic cross-clamping during cardiac surgery. Evidence is accumulating that mechanisms which are operative in experimental ischaemic preconditioning (infarct size limitation) are also operative in these clinical models of repeated reversible ischaemia. Insight into the mechanisms responsible for ischaemic preconditioning could potentially help to develop pharmacological agents which mimic preconditioning. This is especially attractive as several of the ischaemic episodes maybe too short or insufficiently severe to trigger preconditioning. By a synergistic or additive action, the combination of such a stimulus with a low dose of pharmacological agent might result in protective action. If these agents were also to be used for treating cardiovascular conditions, such as the K+ATP channel activator nicorandil for the treatment of angina pectoris, the cardioprotective effect could be a beneficial side effect. The currently available protein kinase C activators are oncogenic, but with the recognition and better understanding of the different subtypes possibly involved in preconditioning, new protein kinase C activators may become available without these side-effects. On the other hand, hearts of patients who regularly experience episodes of ischaemia may be in a more or less permanent state of preconditioning afforded by one of these stimuli or have developed tolerance. In this situation it is likely that (additional) protection by a pharmacological agent cannot be accomplished at that time. It is reassuring, however, that in the animal, preconditioning can be reinstated immediately after the cardioprotection is lost and that it can also be demonstrated in hearts with pathological conditions such as hypertrophy. Finally, in view of the observations that cardioprotection may also be produced by transient ischaemia in other organs, and even by some forms of stress which do not lead to myocardial ischaemia, it could be envisioned that ischaemic preconditioning is only one component of a general form of adaptation.
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PMID:Ischaemic preconditioning: is it clinically relevant? 858 77

The case of a 56-year-old woman who was admitted with an acute anteroseptal myocardial infarction showed severely decreased left ventricular function and regional wall motion abnormalities on planar Tc-99m gated blood pool imaging. Tc-99m sestamibi stress SPECT imaging demonstrated residual peri-infarct ischemia. At angiography, a solitary severe proximal left anterior descending stenosis was successfully dilated. Later, because of recurrent chest pain, a second Tc-99m sestamibi stress-rest SPECT was performed to exclude restenosis. Because the question of viability within the infarct region had also been asked, a gated protocol was applied and compared to TI-201 rest-redistribution SPECT. Both tests pointed to the existence of tissue viability in the septal region, without evidence for stress ischemia. The patient was then medically treated. One year later, because of angina, Tc-99m gated SPECT blood pool imaging showed a spectacular increase in left ventricular function and a dramatic improvement in regional wall motion. Angiographic data confirmed these findings and there was no significant restenosis. Thus, Tc-99m sestamibi gated SPECT may be helpful in predicting viability and recovery of function in patients with severely impaired left ventricular regional wall motion after acute myocardial infarction.
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PMID:Diagnostic value of Tc-99m sestamibi gated SPECT to assess viability in a patient after acute myocardial infarction. 874 84


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