摘要:

ABSTRACTAs a result of the “spatially relative” nature of perfusion defect analysis of stressredistribution thallium‐201 (201T1) scintigrams, hypoperfused myocardial segments may not appear as perfusion defects but they may demonstrate a slow washout rate of201T1 that can be analyzed in a “spatially nonrelative” manner. Quantitative analysis of perfusion defects and slow washout rate of201Tl was performed on scintigrams from 116 consecutive patients with adequate exercise tests, defined as achievement of 85% or more of age‐predicted maximum heart rate or development of angina or ST segment depression. A total of 232 diseased and 116 nondiseased vessels were found in the patients. Additional analysis of slow washout rate significantly (p < .05) improved sensitivity for detection of disease in the left anterior descending (from 74% to 82%). left circumflex (from 40% to 61%), and right coronary arteries (from 78% to 90%) without significant loss of specificity. This improvement resulted from the additional detection of 32 of 232 (14%) diseased vascular distributions when the isolated slow washout rate of201Tl was also deternined. In nine of these 32, isolated slow washout rate was associated with another region with isolated slow washout rate in the contralateral myocardial segment. Coronary arteriography revealed similar degrees of stenosis in the vessels supplying these segment pairs. In 13 of 32 cases, a perfusion defect and a slow washout rate were found in the contralateral segment. Coronary angiography revealed that 10 of these 13 segments with perfusion defects were supplied by vessels in which there was a greater degree of stenosis than that in the vessel supplying the segment with isolated slow washout rate. For the remaining 10 of 32, the contralateral myocardial segment was normal. The initial NIITI distribution in all1 0 myocardial segments in which isolated slow washout rates were noted showed slightly decreased regional 20 Tl activity that was just within the normal range. The coronary artery supplying the myocardial segment with an isolated slow washout rate had stenosis of a greater degree than that supplying the contralateral myocardial segmient in nine of 10 cases. The finding of isolated slow washout rates in these patients with adequate exercise tests was highly specific (95%) for segmiental disease. We conclude that in patients with adequate exercise tests the occurrence of slow regional myocardial washout of201Tl in the absence of perfusion defect significantly improves the detection of segmental myocardial hypoperfusion. This improvement appears to be due to the spatially nonrelative nature of201Tl washout rate analysis, which complements the spatially relative perfusion defect analysis for the assessment of diseased myocardial segnients.

ISSN:0009-7322    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

ABSTRACTOf 866 patients enrolled in our multicenter study. 667 performed a low-level exercise test early after myocardial infarction. most before discharge. Excluding seven patients who died before the test could be considered, there was a 14% 1 year cardiac mortality in 192 patients who did not take the test (150 for medical and 42 for logistic reasons) compared with 5% in those who did (p < .0001). Of those who took the test, 12% subsequently underwent bypass graft surgery compared with 14% of those who did not (p > .05). Decreased mortality in the year after the infarction in those taking the test was associated with an increase in blood pressure to 110 mm Hg or higher (3% vs 18%/e; p < .001), ability to complete the 9 min test (3% vs 8%; p < .01 ), and the absence of couplets (4C/c vs 13%; p < .05) or any ventricular ectopic depolarizations (4% vs 7%. p < .05) before. during, or after exercise. Achievement of a blood pressure of 110 mm Hg or higher during exercise in patients with no evidence of pulmonary congestion on the chest x-ray identified a group of 454 patients (70% of those taking the test) with a 1 year cardiac mortality of 1 clc compared with 13% in the remaining patients (p < .0001). Logistic models showed that the exercise test contributed independent prognostic information for cardiac death, new infarction, and bypass surgery. Results of low-level exercise testing before hospital discharge combined with clinical features of the infarction can effectively identify patients at low risk for subsequent cardiac mortality.

ISSN:0009-7322    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

ABSTRACTTo assess whether gender influenced the outcome of percutaneous transluminal coronary angioplasty (PTCA), we analyzed data from the NHLBI PTCA Registry. Early results were compared in 705 women and 2374 men. Women were older (p < .01) and had more unstable angina (p < .01), and class 3 or 4 angina (p < .01). Men had more multivessel disease (p < .01), prior bypass surgery (p < .01), and abnormal left ventricular function (p < .05). Women had a lower angiographic success rate (60.3 vs 66.2%; p < .01) and had a lower clinical success rate (56.6% vs 62.2%; p < .01). More women had complications (27.2% vs 19.4%; p < .01), but overall frequency of major complications (death, myocardial infarction, emergency surgery) was not different (9.8% vs 9.3%). Women had a higher incidence of coronary dissection (p < .05) and higher in-hospital mortality (1.8% vs 0.7%; p < .01). PTCA-related mortality was nearly six times higher in women (1.7% vs 0.3%; p < .001) and mortality with emergency surgery was more than five time higher (17.4% vs 3.2%; p < .001). Multivariate analysis indicated that female gender was an independent predictor for lower success (p < .05) and early mortality (p < .05) and was the only baseline predictor for PTCA-related mortality. Late results in 2272 patients from centers with virtually complete follow-up of 1 year or longer (mean 18 months) showed comparable or better results in women than men. Men had higher rates of angiographic restenosis (36% vs 22%; p < .01), repeat PTCA (18% vs 10%; p < .01), additional revascularization (27% vs 18%; p < .01), and cumulative mortality (2.2% vs 0.3%; p < .05), and frequency of symptomatic improvement similar to that in women. These NHLBI Registry data indicate that PTCA in women was associated with less favorable short-term outcome, lower initial success rate,and higher mortality rate than in men. However, longer-term results after PTCA were comparable or better in women, with similar symptomatic improvement. lower rates of restenosis, and improved survival compared with men.

ISSN:0009-7322    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

ABSTRACTThe effects of bepridil, a calcium antagonist with a half-life of approximately 42 hr, were assessed in a double-blind, randomized, placebo-controlled crossover trial. Forty-four patients (39 men, five women) with exercise-induced angina pectoris and ST segment depression with exercise testing (modified Bruce protocol) were studied. Compared with placebo bepridil (400 mg daily) increased total exercise time, time to onset of angina, time to 1 mm of ST segment depression, time to 2 mm of ST segment depression, and total work achieved (all p ± .001). Both frequency of angina and nitroglycerin consumption decreased during the bepridil compared with the placebo period (p = .02 and .03, respectively). Minor side effects were noted during both the bepridil and placebo phases. Four patients experienced side effects that limited therapy (dizziness in three and abnormal results of liver function tests in one) and one patient died during the bepridil phase. This study suggests that bepridil, 400 mg daily, is effective for the treatment of exercise-induced myocardial ischemia and angina pectoris.

ISSN:0009-7322    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

ABSTRACTThe efficacy of a single oral dose combination of 120 mg diltiazem and 160 mg propranolol in terminating paroxysmal supraventricular tachycardia (PSVT) was evaluated in 15 patients. All 15 patients underwent electrical induction of PSVT that lasted longer than 15 min, and all underwent randomized crossover placebo and diltiazem and propranolol studies on 2 consecutive days. On each day PSVT was induced and placebo or diltiazem and propranolol was administered 15 min later. Electrical conversion of PSVT was performed when severe symptoms occurred or at the end of 240 min. With placebo PSVT lasted 164 ± 89 (mean ± SD) min; four patients had spontaneous conversion. With diltiazem and propranolol PSVT lasted 39 ± 49 min (p < .001); 14 patients had spontaneous conversion in an average of 27 ± 15 min. None of the 14 patients had electrical reinduction of sustained PSVT after conversion. The sinus nodal recovery time during spontaneous or electrical conversion of PSVT was 911 ± 459 msec with placebo and 1076 ± 270 msec with diltiazem and propranolol (NS). Two patients developed transient second-degree atrioventricular block and junctional rhythm while on diltiazem and propranolol. Serum diltiazem and propranolol levels (ng/ml) after diltiazem and propranolol in five patients were, respectively, 49 ± 26 and 108 101 at 15 min, 232 ± 147 and 228 ± 148 at 30 min, 254 ± 169 and 370 ± 393 at 45 min, 280 ± 115 and 209 ± 189 at 60 min, 188 ± 72 and 268 ± 264 at 120 min, and 118 ± 57 and 265 ± 148 at 240 min. Follow-up study after 5.6 ± 0.9 months revealed 51 spontaneous episodes of PSVT in the patient group; 50 of the 51 episodes were converted after the single oral dose of the diltiazem and propranolol combination, with a conversion time of 21 ± 16 min. In conclusion, a single oral dose combination of diltiazem and propranolol effectively terminates acute episodes of PSVT and may be considered the therapeutic regimen of choice in selected patients.

ISSN:0009-7322    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

ABSTRACTThis study was performed to characterize selected pharmacologic properties and effects on the fibrinolytic system of tissue-type plasminogen activator synthesized by recombinant DNA technology (rt-PA) in 12 patients treated for coronary thrombosis. rt-PA was infused parenterally (by the intracoronary route in four patients and intravenously in eight) in doses of 8.3, 12.5, or 16.7, ug/kg/min for 30 to 60 min, yielding a total dosage of 20 to 40 mg/patient. The drug induced coronary thrombolysis in 10 of the 12 patients treated (83%), including six of the eight given rt-PA intravenously. No bleeding complications were encountered. Serial blood samples were obtained before, during, and after infusion of rt-PA and analyzed for t-PA antigen (i.e., immunoassayable rt-PA protein), functional fibrinolytic activity attributable to rt-PA, fibrinogen, plasminogen, a2-antiplasmin, fibrinogen degradation products, prothrombin time, activated partial thromboplastin time, and protaminecorrected thrombin time. Pretreatment plasma t-PA antigen levels averaged 16.5 ± 5(SD) ng/ml. Peak plasma values were generally proportional to dose, averaging 3330 ± 1201 ng/ml. Approximately 90% of peak level was reached in 30 min, with a plateau at peak reached within 40 min. Functional t-PA activity increased monotonically in a comparable fashion. Curves for disappearance of both t-PA antigen and functional activity from plasma were monoexponential for at least two half-lives (r = .99 for both) and were concordant. The observed half-lives were similar, averaging 8.3 and 9.1 min, respectively. Changes in concentrations of fibrinogen were transient and modest (17 ± 6% iof baseline). Plasminogen and a2-antiplasmin levels declined moderately to 51 ± 6% and 32 ± 7% of pretreatment values at the end of infusion of rt-PA. Prothrombin time, protamine-corrected thrombin time, and assay of fibrinogen degradation products corroborated the lack of a lytic state. Thus, desirable levels of rt-PA can be achieved consistently with short-term infusions of appropriately selected doses without induction of a systemic lytic state predisposing to bleeding.

ISSN:0009-7322    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

ABSTRACTThis study assessed the long-term effects of thrombolytic treatment in patients with acute massive pulmonary embolism (PE). Seven patients with PE that followed deep-vein thrombosis underwent pulmonary angiography and pressure measurements before and 6 ± 3 days (mean ± SD) and 15 ± 4 months after treatment with intrapulmonary infusions of urokinase (average dose 1724 U/kg.hr) and heparin (average dose 17 U/kg.hr). Treatment was guided by daily measurements of pulmonary arterial (PA) pressure and was continued until PA pressure had normalized (average of days). Late after treatment patients retumed for pulmonary angiographic examination, right heart catheterization at rest and during bicycle exercise, and phlebography of the deep veins of both legs. Pulmonary angiograms showed massive obstruction before therapy (Walsh index 15 ± 2 points of maximum of 18 points), which was improved 6 days (3 ± 3 points) and 15 months (1 ± 2 points) after therapy. Mean PA pressure declined from 37 ± 9 to 13 ± 3 mm Hg after 6 days and to 15 ± 3 mm Hg after 15 months. No recurrence of PE was observed. In six of seven patients at rest and during bicycle exercise (up to 100 W) in the supine position mean PA pressure and total pulmonary resistance remained within normal limits. Over the short term all patients showed clinical signs of deep-vein thrombosis; 15 months later four patients had normal deep veins, but three patients had still phlebographic signs of old thrombosis. Thus, after thrombolytic treatment of acute massive PE normal pulmonary arteriograms were obtained in six of seven patients studied; furthermore, the reserve capacity of the pulmonary vasculature as assessed during heavy exercise was normal in these patients.

ISSN:0009-7322    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

ABSTRACTA multivariate logistic regression equation was used to evaluate variables related to successful intracoronary thrombolytic therapy. One hundred seventeen patients with a totally occluded infarct-related artery were randomly given ostial infusions of urokinase or streptokinase in a blinded study. The opening rate was 57%. The agent used and time from onset of symptoms to beginning of treatment did not significantly influence opening rate (p > .25). The site of occlusion was a strong predictor of opening rate (p = .0004). The anterior descending coronary artery was successfully opened more frequently than the left circumflex or right coronary artery (p = .012). Presence of collaterals adversely affected the recanalization rate in all groups (p = .0004). These variables had an additive effect on the probability of opening. Patients with proximal anterior descending occlusion and no collaterals had a 90% recanalization rate, while those with distal occlusions in vessels other than the anterior descending and with collaterals had only a 24% chance for reperfusion. Thus location of occlusion and presence or absence of collaterals may strongly influence opening rates.

ISSN:0009-7322    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

ABSTRACTTo test the relative accuracy of Doppler echocardiographic peak frequency and turbulence parameters in assessing aortic stenosis, we constructed a pulsatile flow model that simulated human left ventricular and aortic pressures, flow, and anatomy. Continuous wave‐measured peak frequencies and pulsed Doppler‐measured turbulence were determined in the model ascending aorta for nine stenotic valve areas for each of five different flow rates. The mean squared systolic peak frequency (MSPF) and turbulence spectral envelope area (SEA) were regressed against the mean systolic gradient (r = .94, SEE = 5.6 mm Hg; and r = .96, SEE = 1.2 mm Hg, respectively). SEA was more accurate than MSPF at moderate‐to‐high degrees of stenosis and exhibited a smaller standard error. MSPF was more accurate than SEA in mild stenoses, where SEA tended to overestimate gradients. When flow data were included in a multiple regression analysis, both MSPF and SEA provided fair predictions of actual effective valve areas (r = .90 and r = .94, respectively). Use of high pulse‐repetition‐frequency Doppler echocardiography significantly reduced aliasing problems common to pulsed Doppler techniques.

ISSN:0009-7322    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

ABSTRACTIn defibrillation, current flow depends on the energy selected and the transthoracic impedance. If transthoracic impedance is high, current flow may be inadequate to defibrillate. We developed a method by which high transthoracic impedance is automatically compensated for by an increase in operator-selected energy when impedance is high. Transthoracic impedance was predicted in advance of the first shock by passing a low-level current between the defibrillator electrodes during the defibrillator charge cycle; a microprocessor monitored current flow and determined impedance. In 28 mongrel dogs we manipulated transthoracic impedance by placing glycerin-soaked gauze pads between the paddle electrodes and the chest. If the predicted impedance exceeded a preset value, the delivered energy was automatically increased by 40% or 100%. Using this impedance-based energy adjustment technique, we found significant improvements in current flow and success rate of shocks when energy was automatically increased to compensate for high transthoracic impedance. The use of transthoracic impedance as a basis for energy adjustment appears a promising technique to minimize the hazards of high electrical energy; it allows low-energy shocks in most patients while avoiding inappropriate low energies in patients with high impedance. Clinical trials are justified.

ISSN:0009-7322    

出版商:OVID    

年代:1985

数据来源: OVID