Predischarge exercise echocardiography in patients with unstable angina who respond to medical treatment.

The diagnostic and prognostic value of predischarge exercise echocardiography (echo) was assessed prospectively in 36 patients with unstable angina soon after stabilization on medical treatment. Two-dimensional echo was performed at rest and immediately after a symptom-limited exercise test. Patients with previous myocardial infarction, coronary revascularization, left bundle-branch block and dilated cardiomyopathy were excluded. Left ventricular regional wall motion was analyzed visually and a wall motion score index (WMSI) was derived. Patients were followed prospectively for an average period of 26 months (range 16-34 months). The study end points were a new cardiac event defined as acute myocardial infarction or a need for coronary revascularization because of a recurrence of severe medically refractory angina. Sixteen patients (44%) had positive exercise electrocardiography (ECG), while exercise echo was positive in 22 patients (61%). Of 28 patients undergoing coronary angiography, 23 had significant coronary artery disease (CAD). The sensitivity of exercise ECG in detecting CAD was 61% while the corresponding result was 83% for exercise echo. Cardiac events occurred in 21 patients (58%). Exercise ECG was positive in 12 of these patients (57%), while a positive exercise echo was found in 17 patients (81%). There were significantly more patients with positive exercise echo among patients experiencing cardiac events than among those without cardiac events (p less than 0.01). In patients with CAD, WMSI decreased significantly after exercise (p less than 0.05). Exercise WMSI was also significantly lower in patients with CAD than in those without CAD (p less than 0.02). Exercise WMSI also discriminated patients with cardiac events from those without such events (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)     

稳定性心绞痛在骨科关节置换术后致心血管意外的表现

目的研究分析稳定性心绞痛患者经骨科关节置换术治疗致心血管意外的相关因素。方法选取2016年3月—2017年12月本院接收的68例稳定性心绞痛患者作为研究对象。所有患者均经骨科关节置换术治疗,采用Logistic回归模型对心血管意外相关因素进行分析。结果多因素分析显示冠心病合并肥胖、冠心病合并高血压、冠心病合并糖尿病、心功能Ⅱ～Ⅲ级是患者行关节置换术诱发心血管意外的独立危险因素。结论行关节置换术的稳定性心绞痛患者若冠心病合并肥胖、冠心病合并糖尿病、Ⅱ级<心功能<Ⅲ级,会增加心血管意外的发生风险,临床应加大重视度,对患者进行细致、全面观测,严防心血管意外事件发生。     

Mechanisms of nitrate tolerance

Summary There is now little dispute that clinical tolerance of organic nitrates occurs, particularly when these drugs are used by themselves to treat patients with stable angina pectoris and congestive heart failure. Classical hypotheses of nitrate tolerance suggest the phenomenon to result from vascular depletion of critical sulfhydryl groups, which are necessary to bring about vasorelaxation from nitrates. While this mechanism of nitrate tolerance probably operates when isolated blood vessels are exposed to high concentrations of nitrate in vitro, there is little evidence to suggest that it contributes to clinical nitrate tolerance. Instead, emerging data suggest that nitrates can cause significant shifts in fluid distribution and secretion of neurohormonal factors that can modulate their vasorelaxant effects. use of angiotensin converting enzyme inhibitors and diuretics in conjunction with nitrates may alleviate the development of tolerance, but the experience has not been universally favorable. Other receptor-effector systems that affect cardiovascular function, such as the adrenergic system, may also be affected by nitrate tolerance. The mechanisms of nitrate tolerance are therefore likely to be multifactorial, involving vascular biochemical changes, physiologic compensation, and possibly receptor regulation.     

Ointments and transdermal nitroglycerin patches for stable angina pectoris

Summary Nitroglycerin (NTG) ointment is used for the prophylaxis against angina pectoris, but there are no data to support its effectiveness during long-term therapy. Continuous, once-daily application of isosorbide dinitrate cream produces tolerance with complete loss of efficacy within 1 week. Nitroglycerin patches are very popular and continuous once-daily application is still claimed by some investigators to provide 24 hour antiischemic and antianginal efficacy. This claim is based on data from postmarketing studies in a very large number of patients and placebo-controlled studies in smaller groups of patients from Italy, Yugoslavia, Greece, and Germany. In contrast, studies from the United States, Canada, England, and some centers in Germany have failed to show superiority of patches over placebo during continuous therapy. This controversy was addressed by the NTG cooperative study group, in which a total of 562 patients who were responders to sublingual nitroglycerin were studied. Patients received either placebo or NTG patches delivering low (15–30 mg/24 hr), moderate (45–60 mg/ 24 hr), or large (75 and 105 mg/24 hr) amounts of NTG. Four hours after the initial application, NTG patches increased exercise duration compared to placebo, but this beneficial effect had disappeared by 24 hours. Furthermore, after 8 weeks of continuous therapy, none of the NTG patches were superior to placebo, whether patients were or were not taking concomitant beta-blockers. Therefore, current opinion is that continous therapy with NTG patches produces pharmacologic tolerance and is ineffective. Pharmacologic tolerance can be minimized when patches are applied every morning and removed after 10–12 hours at night. However, patches delivering >15 mg NTG/24 hr are required to maintain an increased exercise duration for up to hour 8 after the patch application. Intermittent therapy with patches, however, may lead to rebound nocturnal angina in some patients. Also, intermittent therapy with patches has been associated with worsening of exercise performance in the morning prior to the patch renewal, compared to therapy with placebo patches. This has been referred to as the zero-hour effect and probably represents a rebound phenomenon following nitrate withdrawal. Patients experiencing either nocturnal or early morning angina during intermittent therapy with patches should either be switched to oral long-acting nitrates or should in addition be treated with a beta-blocker, provided there are no contraindications to beta-blocker treatment.The opinions expressed here are those of the authors and should not be taken as those of FDA.     

Once- versus twice-daily administration of controlled-release isosorbide-5-mononitrate 60 mg in the treatment of stable angina pectoris: A randomized, double-blind, cross-over study

Thirty-seven patients with chronic, stable angina pectoris wereincluded in a randomized, double-blind cross-over study to assessthe efficacy of once- and twice-daily dosage regimens of 60mg isosorbide-5-mononitrate, in a controlied release formulation(5-ISMN Durules^® Astra). After 2 weeks of treatment, duringa symptom-limited bicycle ergometer exercise test performed3 h after the dose, the time to 1 mm ST segment depression wasobserved to be longer by once-daily than by a twice-daily dosageregimen (614 ± 165 vs 561 ± 148 s, P<0·01).The time to the end of exercise was also significantly prolongedby once-daily dosage, as compared with placebo (693 ±158 and 645 ± 173 s, respectively; P<0·05),which was not observed with the twice-daily regimen. Both dosageregimens still had a significant effect on the prolongationof the time to onset of angina 9 h after the dose: 420 ±164 s by placebo, 492 ± 161 s by once-daily dosage; P<0·01and 466 ± 154 s by twice-daily dosage; P<0·05.Anginal attack rate and nitroglycerin consumption was significantlylower during the once-daily dosage period as compared with placebo;this difference was not evident during the twice-daily administrationof the drug. Controlled-release 5-ISMN 60 mg given once daily was effectivein angina pectoris patients for at least 9 h after the doseand showed no clinical signs of tolerance after 2 weeks of thetreatment. Attenuation of the clinical effect was observed withthe twice-daily (in 12 h intervals) dosage regimen, presumablycaused by constantly high 5-ISMN plasma concentration.     

Bicoronary-pulmonary fistulae with coexistent mitral valve prolapse: a case report and literature review of coronary-pulmonary fistula

Bicoronary-pulmonary artery fistulae are rare congenital coronaryartery fistulae. We report the case of a 57-year-old man whopresented with biventricular failure and angina pectoris. Atangiography the coronary arteries were normal, but bicoronary-pulmonaryfistulae were noted; severe mitral regurgitation secondary tomitral valve prolapse was also present. At right heart catheterizationthe calculated left to right shunt was 2.1. Fistula ligationand repair of both mitral and tricuspid valves was undertaken.The literature regarding coronary-pulmonary fistula is alsoreviewed.     

Relation between changes in severity of coronary artery stenosis and anginal patterns

Although myocardial ischemia causes angina pectoris, angina and the severity of coronary artery stenosis in individuals do not correlate. However, changes in anginal status over time correlated with changes in the severity of coronary artery stenosis as determined by repeated coronary arteriograms has not been previously studied. Coronary arteriograms, done both at entry into the Program on the Surgical Control of the Hyperlipidemias (POSCH) and 3 years later, were blindly graded for changes in overall severity of coronary artery stenosis according to protocol by the POSCH Arteriography Review Committee. Arteriographic and clinical data from 376 control subjects (347 men, 29 women) were analyzed. There was no statistically significant relation over a long-term (3 year) period between the absence, presence, development, or disappearance of angina pectoris and changes in coronary artery stenosis severity as determined by coronary arteriography. © 1994 Wiley-Liss,Inc     

Concomitant use of nitrates,calcium channel blockers,and beta blockers for optimal antianginal therapy

Despite the introduction of new mechanical techniques for revascularization, pharmacologic therapy continues to be the mainstay of antianginal therapy. The conventional antianginal medications, which include nitrates, beta blockers, and calcium channel blockers, act to correct the imbalance between myocardial supply and demand by increasing coronary blood flow, reducing myocardial oxygen requirements, or both. All three are appropriate for the management of angina caused by a fixed coronary obstruction, but nitrates and calcium channel blockers, which not only reduce demand but also increase supply, are preferred in cases of angina believed to involve a significant increase in vasomotor tone. Because of the different yet complementary mechanisms of action of the three classes of anti-ischemic drags, use of these agents in combination is a rational approach to the treatment of angina unresponsive to monotherapy. Such combinations have been shown to enhance the therapeutic response achieved with single-agent therapy. In addition, the pharmacologic action of one of the components of the combination regimen may serve to offset side effects typically associated with the other.     

Electrophysiologic Basis for T Wave Alternans as an Index of Vulnerability to Ventricular Fibrillation

Electrophysiologic Basis for T Wave Alternans. Substantial evidence indicates that T wave alternans is an intrinsic property of ischemic myocardium. The electrophysiologic basis appears to be spatial and temporal heterogeneity of repolarization resulting from changes in action potential morphology rather than in activation sequence. Ischemia-induced changes in postrepolarization refractoriness and depressed electrical restitution of action potential duration have also been implicated. The main underlying ionic basis for T-wave alternans during coronary occlusion appears to be derangements in intracellular cycling of calcium. Accumulation of potassium in the extracellular space adjoining ischemic cells and disruption in electro-genie sodium-calcium exchange may also be involved. In humans, T wave alternans has been observed in Prinzmetal's and classical angina, angioplasty, and bypass graft occlusion. Under these conditions associated with acute myocardial ischemia, alternans is restricted to the ischemic zone, and alternation in action potential morphology is an underlying factor. Recently, repolarization alternans has been shown to be a statistically significant predictor of the results of electro physiologic testing and arrhythmia-free survival in individuals with and without organic heart disease. Collectively, these observations provide a rationale for quantitation of T-wave alternans magnitude for assessment of vulnerability to life-threatening ventricular arrhythmias both in response to and independent of the effects of myocardial ischemia.     

Recurrence of prinzmetal angina seven years following aortocoronary bypass surgery: A clinical and angiographic follow-up

A patient with Prinzmetal angina and ST segment elevation in the anterior ECG leads became asymptomatic after a 50% left anterior descending coronary artery stenosis was bypassed. However, seven years later Prinzmetal angina recurred but with ST segment elevation in the inferior ECG leads. Although the coronary bypass graft had remained patent, the proximal and distal left anterior descending coronary artery was occluded. No significant stenosis was present in the right coronary artery. Perhexiline maleate controlled his symptoms but when the drug was stopped because of side effects an acute inferior myocardial infarction occurred.