摘要:

Identification of a characteristic morphology of a coronary stenosis likely to result inmyocardial infarction would facilitate the prospective evaluation of infarct prevention strategies and dentification of high-risk patients. We postulated that coronary lesions associated with recent myocardial nfarction or unstable angina would have an angiographic morphology suggesting disruption of an therosclerotic plaque and would appear morphologically different from lesions associated with chronic table angina. To test this hypothesis, quantitative coronary angiography (Brown-Dodge method) as performed in 15 patients 4 to 30 days after myocardial infarction, in 10 patients with the abrupt nset of unstable angina and single-vessel coronary disease, and in 15 patients with chronic stable ngina without prior myocardial infarction. Serial arterial diameters (20 to 40) within each lesion weredetermined and the degree of luminal irregularity was quantitated by calculation of an “ulceration” ndex. The majority of all lesions analyzed resulted in severe luminal stenosis (mean 78% area stenosis,all groups). Despite small differences in mean lesion severity among groups, overlap in the degree of uminal compromise prevented precise classification of lesions associated with myocardial infarction r unstable angina based on percent stenosis or minimum luminal cross-sectional area. The meanulceration index of lesions in patients with unstable angina and in the infarct-related vessel in those with cute myocardial infarction was 0.62 ± 0.05 (± SEM) and 0.61 ± 0.03, respectively. These were ignificantly different from the mean ulceration indexes of lesions in patients with stable angina (0.96 0.01, p<.05) or from indexes of lesions in the noninfarct-related vessel of patients with acute nfarction (0.90 ± 0.02, p<.05). None of 10 lesions associated with unstable angina and 14 of 15 nfarct-related lesions had an ulceration index less than 0.78. All lesions associated with stable angina nd each lesion in the noninfarct-related vessel in patients wth infarction had an ulceration index ofgreater than 0.83. The ulceration index did not vary significantly with the degree of luminal stenosis or rior treatment with thrombolytic agents. These data provide quantitative evidence that lesions associated ith myocardial infarction or the abrupt onset of unstable angina are of a similar characteristic ngiographic morphology that is suggestive of plaque disruption and not commonly seen in lesions ssociated with chronic stable angina. The ulceration index may provide a mechanism for the prospective dentification of high-risk coronary lesions Circulation.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Incidence and significance of pericardial effusion in patients with acute myocardial infarction (AMI) have not been established. To evaluate these issues, we studied prospectively 138 consecutive patients with AMI. An echocardiogram was obtained in each 1, 3, and 10 days and 3 and 6 months after admission. Fifty four patients with unstable angina and 57 without heart disease were studied as controls. Echocardiographic diagnostic criteria of pericardial effusion were established from 33 additional patients undergoing surgery. Pericardial effusion was found in 28% of patients with AMI. Twenty-five percent of patients with AMI had pericardial effusion on the third day, vs 8% of patients with unstable angina (p < .02) and 5% of patients without heart disease (p < .01). At 1, 3, and 10 days and 3 and 6 months prevalence of pericardial effusion was 17%, 25%, 21%, 1 1%, and 8%, respectively. There was no case of tamponade. Pericardial effusion was more common in anterior AMI (p < .02) and in patients with heart failure (p < .05) but it was not significantly associated with early pericarditis, peak creatine kinase-MB, the level of anticoagulation, or mortality. Thus, pericardial effusion is a common event in patients with AMI (incidence of 28%), but does not result in specific complications. The reabsorption rate of pericardial effusion is slow and, in our experience, mild or moderate pericardial effusion does not preclude heparin therapy.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

While there has been wide general acceptance of Doppler methods that use the simplified Bernoulli relationship to estimate pressure gradients across stenotic orifices, there is still ongoing controversy related to potential sources of error in the method. In this study we tested accuracy of ultrasound Doppler measurements of flow velocity when compared with the gold standard of laser light Doppler anemometry in a pulsatile flow model of pulmonic stenosis in vitro. We tested two commercially available Doppler systems and examined steered and nonsteered, parallel, and off-axis and anglecorrected velocity determinations using continuous-wave and high-pulse repetition frequency (HPRF) methods. We also examined the potential range of error in the simplified Bernoulli method. One hundred and twenty individual flow states were examined with three stenotic valve orifices (3.0, 1.0, and 0.5 cm2 flow area) to measure velocities up to 620 cm/sec. A very high correlation coefficient was obtained for the comparison of laser Doppler anemometric and ultrasound velocity recordings by the nonsteered continuous-wave technique (r = .99, SEE = 17.9 cm/sec), but there was a tendency for underestimation of higher velocities when the transducer was positioned at 30 degrees and the ultrasound beam was steered so as to be parallel to the visualized flow jet (r = .98, SEE = 29.6 cm/sec). The HPRF ultrasound Doppler technique was also highly accurate in this optimized setting for measuring velocities (r = .99, SEE = 17 cm/sec), but also slightly underestimated the highest velocities. Our results also verified the accuracy of the simplified Bernoulli equation for converting instantaneous velocity measurements to estimated peak instantaneous gradient (r = .97, SEE = 8.4 mm Hg).

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

The efficacy and safety of a new antitachycardia pacing technique, self-adapting decremental overdrive pacing, was assessed in patients with clinical ventricular tachyarrhythmias who underwent programmed ventricular stimulation and serial drug testing. The three phases of this study involved a learning/experience phase, followed by intrapatient comparison of decremental overdrive pacing with conventional antitachycardia pacing modalities of overdrive burst ventricular pacing, and diastolic scanning with single (S2) and double (S2S3) ventricular extrastimuli. The final phase involved intrapatient comparison of automated decremental overdrive pacing with overdrive burst ventricular pacing in patients with ventricular tachycardia (VT) cycle lengths of 280 msec or greater. Decremental overdrive pacing was superior to overdrive burst pacing and diastolic scanning (S2S3 and S2) (83% vs 38%, 50%, 9%) in patients with VT cycle lengths of 280 msec or greater. Automated decremental overdrive pacing as applied in the final phase was the most efficacious modality, terminating 92% of VT episodes compared with 56% for overdrive burst pacing in the same patients.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

We evaluated the efficacy and the safety of medium- (240 mg/day) and high-dose (360 mg/day) diltiazem alone and in combination with digoxin when used for control of heart rate in 12 patients with chronic atrial fibrillation. Medium-dose diltiazem was comparable to therapeutic dose of digoxin at rest (88 ± 19 vs 86 + 12 beats/min) but superior during peak exercise (154 23 vs 170 + 20 beats/min; p < .05). High-dose diltiazem resulted in better control of heart rate than digoxin both at rest (79 17 beats/min; p < .05) and exercise (136 + 25 beats/min; p < .05) but was associated with side effects in 75% of the patients. Combined therapy of digoxin and diltiazem enhanced the effect of digoxin alone and resulted in significantly better control of heart rate at rest (67 + 16 beats/min with medium-dose and 65 + 15 beats/min with high-dose diltiazem) and during peak exercise (132 + 32 and 121 ± 24 beats/min, respectively). However, the difference in heart rate between these two doses was not significant. Reduction of heart rate combined with concomitant effect on blood pressure 0resulted in a significant fall in pressure-rate product at rest from 10,077 + 1708 mm Hg/min on digoxin alone to 7877 + 1818 mm Hg/min after the addition of medium-dose diltiazem (p < .05) and during exercise from 25,670 + 3606 to 18,439 4115 mm Hg/min (p < .05). Continued therapy with digoxin combined with diltiazem 240 mg/day for 21 ± 8 days in nine patients showed persistent effect on heart rate and blood pressure without any toxic manifestations or change in serum digoxin (1.5 + 0.4 vs 1.3 + 0.4 ng/ml) or plasma diltiazem concentrations (204 72 vs 232 129 ng/ml). In conclusion, medium-dose diltiazem when combined with digoxin is an effective and safe regimen for the treatment of patients with chronic atrial fibrillation and enhances digoxin-mediated control of heart rate both at rest and during exercise.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Aspirin plus dipyridamole reduces platelet accumulation on short-term Dacron vascular grafts in man. To determine whether drug inhibition of platelet deposition is sustained on older grafts, we studied 18 men aged 41 to 87 years who had Dacron aortic bifurcation grafts in place a mean of 43.4 months (range 9.8 to 121.0) before and during short-term therapy with aspirin (325 mg tid) plus dipyridamole (75 mg tid). During both the baseline and drug studies, indium-111 (1'In) platelet deposition was quantitated by two techniques, standard planar imaging performed at 24, 48, and 72 hr after injection of platelets and single photon emission computed tomographic imaging performed at 24 and 72 hr after injection. All analyses were performed in a blinded fashion. On both the planar and tomographic images, platelet accumulation on the graft was quantitated by a graft/blood ratio that compared activity in the graft to simultaneously collected whole blood 1 'In platelet activity. Aspirin plus dipyridamole reduced the tomographic graft/blood ratio at 24 hr (20.6 + 3.5 vs 17.3 + 2.5) (± SEM) and at 72 hr (29.0 ± 4.8 vs 25.0 ± 4.1) after injection of platelets (p = .02). Similarly, the planar graft/blood ratio was reduced at 24 hr (2.7 ± 0.5 vs 2.4 ± 0.5), 48 hr (3.7 ± 0.9 vs 3.1 ± 0.7), and 72 hr (4.0 ± 0.9 vs 3.6 ± 0.8) (p = .04). We conclude that aspirin (325 mg tid) plus dipyridamole (75 mg tid) reduces platelet accumulation on long-term Dacron vascular grafts.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

The value of the addition of f8-blockers to coronary vasodilator therapy in the treatment of patients with unstable angina at rest is controversial. We conducted a double-blind, randomized, placebo-controlled 4 week trial of propranolol in 81 patients with unstable angina, 39 of whom were assigned to placebo and 42 of whom received propranolol in a dose of at least 160 mg daily. All patients were also treated with coronary vasodilators, including 80 mg nifedipine daily and long-acting nitrates. The incidences of cardiac death, myocardial infarction, and requirement for bypass surgery or coronary angioplasty did not differ between the two groups (propranolol = 16; placebo = 18). The propranolol group had a lower cumulative probability of experiencing recurrent resting angina than the placebo group (p = .0 13), and over the first 4 days of the trial the mean number of clinical episodes of angina (propranolol 0.9 + 0.2, placebo 1.8 ± 0.3, p = .036), duration of angina (propranolol 15.1 + 4.3 min, placebo 38.1 + 8.4, p = .014), and nitroglycerin requirement (propranolol 1.1 + 0.3 tablets, placebo 3.5 + 0.8, p = .003) were also fewer. Continuous electrocardiographic recording for ischemic ST segment changes revealed fewer daily ischemic episodes in the propranolol group (2.0 + 0.5) than in the placebo group (3.8 + 0.7, p = .03), and a shorter duration of ischemia (propranolol 43 + 10 min, placebo 104 + 28 min, p =.039). Thus propranolol, in patients with unstable angina, in the presence of nitrates and nifedipine is not detrimental and reduces the frequency and duration of symptomatic and silent ischemic episodes.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

The efficacy and safety of a 3 hr, 80 mg intravenous infusion of recombinant tissue-type plasminogen activator (rt-PA) were investigated in 47 patients with acute myocardial infarction. Coronary angiography, performed before the administration of rt-PA and for 90 min thereafter, demonstrated that 37 patients had total coronary occlusion before therapy. After 90 min of rt-PA (50 mg), reperfusion of the infarct-related artery was observed in 25 patients (68%). Continuous infusions of heparin for anticoagulation were administered for 8 to 10 days. Of 36 patients who underwent follow-up coronary cineangiography, 21 had initially presented with total occlusion and had experienced reperfusion at 90 min. Sustained perfusion of the infarct-related artery was observed in 14 (67%) of these 21 initially reperfused patients. Late angiography was performed in nine patients who initially demonstrated subtotal occlusion of the infarct-related artery; sustained perfusion was observed in eight (89%). Significant bleeding was observed in 15 patients (32%). A hematoma at the site of the acute catheterization accounted for most instances of significant bleeding (1 1/15, 73%). Administration of rt-PA resulted in a significant decline in fibrinogen and plasminogen while amounts of fibrin(ogen) degradation products rose. In no patient, however, did fibrinogen levels decline to less than 140 mg/dl. Thus, rt-PA, administered as a brief 80 mg intravenous infusion, is capable of restoring blood flow in a high proportion of patients with acute myocardial infarction due to total coronary obstruction. Declines in plasma fibrinogen and plasminogen are observed. If combined with heparin anticoagulation and invasive vascular procedures, significant bleeding is a common complication. Despite anticoagulation with heparin after rt-PA, reocclusion of the reperfused infarct-related artery occurs in one-third of patients.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Twenty-nine patients with acute myocardial infarction were treated with recombinant human tissue-type plasminogen activator (rt-PA). The incidence of acute coronary reocclusion and its prevention by a maintenance infusion of rt-PA were studied. Intravenous rt-PA was given at a rate of 0.4 to 0.75 mg/kg over 60 to 120 min after angiographic documentation of complete coronary occlusion. Reperfusion was accomplished within 1 hr in 24 of 29 patients (83%) and was associated with a decrease of the plasma fibrinogen level by 20%. In a first group of 13 patients, 1 1 of whom were successfully reperfused, prevention of reocclusion was attempted with heparin anticoagulation. However, acute reocclusion within 1 hr after cessation of rt-PA was demonstrated angiographically in five of these patients (45%). Quantitative angiographic analysis indicated that acute reocclusion only occurred in patients with 80% or greater residual stenosis. In patients with less than 80% residual stenosis, heparin anticoagulation was sufficient to maintain patency during the hospital stay in four of five patients. In a second group of patients (n = 16), 13 of whom underwent reperfusion with intravenous rt-PA, seven demonstrated a residual stenosis of 80% or greater. These patients were given heparin and, in addition, 10 mg of rt-PA per hour for 4 hr. None developed acute angiographic reocclusion or clinical signs of reocclusion during the hospital stay. Repeat angiography at 10 to 14 days confirmed persistent patency in six of the seven patients. The maintenance infusion resulted in only a moderate additional drop in fibrinogen, while a steady-state plasma rt-PA level of 750 250 ng/ml was maintained. In five of the six patients with less than 80% residual stenosis maintained on heparin therapy alone, follow-up angiography demonstrated persistent patency. These findings strongly suggest that a maintenance infusion of rt-PA may prevent or greatly reduce the reocclusion rate in patients with 80% or greater residual stenosis after coronary reperfusion with rt-PA.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

The effects of the immunosuppressant drug cyclosporine were studied in the murine model of Coxsackie B3 myocarditis. Ten BALB/c mice, given daily cyclosporine (15 mg/kg) intraperitoneally but not infected, were normal in all respects after 2 weeks. All 32 IALB/c mice infected, but given no cyclosporine, survived and had moderate myocardial mononuclear infiltrates and minimal necrosis at 7 and 14 days. In contrast, 24 mice concurrently infected and given cyclosporine had a high mortality rate (75%) and a significantly attenuated mononuclear infiltrate in the presence of enhanced necrosis when compared with control infected mice. Sixteen mice started on the drug 1 week after infection had a lower mortality rate (55%), but very similar histologic abnormalities. In contrast to negligible or no virus in the hearts of infected mice that were not given cyclosporine, drug treated, infected groups had easily detectable virus in their hearts 14 days after infection. An identical study in Swiss ICR mice yielded similar results. Cyclosporine, when given early during acute murine Coxsackie

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID