摘要:

Magnetic resonance (MR) imaging was performed in 14 patients with intracavitary cardiac tumors diagnosed by echocardiography. Except in the patients whose echocardiograms were diagnostic of atrial myxomas, this modality contributed important additional anatomic information regarding the tumor's relationship to the normal intracardiac structures and/or its extension to the adjacent vascular and mediastinal structures. The MR findings correlated extremely well with the findings in all 12 patients who underwent surgical exploration or postmortem examination, and in the other two patients, MR guided the decision to obtain transvenous biopsy samples of their right heart masses.

ISSN:0009-7322    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

Cine magnetic resonance imaging (MRI) was used for postoperative evaluation of eight patients who underwent intra-atrial baffle procedure for surgical repair of D-transposition of the great arteries (D-TGA). Their ages ranged from 9 months to 8 years. Younger patients were sedated with chloral hydrate (80 to 100 mg/kg) orally. MRI was performed with use of a General Electric Signa system operating at a field strength of 1.5 tesla. A body or head coil was used depending on the size of the patient. Images were obtained by use of a technique of gradient-recalled acquisition in steady state (GRASS) that utilizes a low flip angle and shorter repetition and echo times. Five patients had widely patent venae cavae and three had superior vena caval obstruction at the junction of the right atrium with a dilated azygos vein. There was no evidence of pulmonary venous obstruction in any of the patients. Right ventricular function was assessed in four patients and their ejection fractions ranged from 58% to 81%. Tricuspid and mitral regurgitation were observed in three and two patients, respectively. Both right and left ventricular outflow tracts were well visualized and showed no evidence of obstruction. Cine MRI is an entirely noninvasive, nonionizing, and safe procedure in young patients and appears to be a valuable alternative method for evaluating patients after surgical repair of D-TGA. With advancing technologies and an accumulation of experience with cine MRI, it appears that this new technique will play an important role in patient care for children with congenital heart disease.

ISSN:0009-7322    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

We investigated the relationship between electrical alternans and cardiac electrical stability in a series of 20 dog experiments and in a pilot clinical study. Electrical alternans was detected in both the QRS complex and the ST-T wave by use of a novel multidimensional spectral technique. The magnitude of the alternation was expressed as the alternating electrocardiographic morphology index (AEMI), expressed as parts per million of waveform energy. Electrical stability in the dog preparations was assessed via the ventricular fibrillation threshold measurement, and in the clinical studies via programmed stimulation. In 10 dog experiments, systemic hypothermia resulted in a 60% decrease in ventricular fibrillation threshold (VFT) (p < .0001) and a significant increase in both AEMI(QRS) from 3.7 ± 3.0 to 1448 ± 548 (p < .0001) and AEMI(ST-T) from 43.9 ± 18.4 to 19,178 ± 5579 (p < .0001). In 10 dog experiments, transient coronary artery ligation also resulted in a 60% decrease in VFT (p < .0001), an increase from 76.3 ± 46.5 to 245 ± 11 in AEMI(QRS) (p < .05), and an increase from 842 ± 505 to 1365 ± 392 in AEMI(ST-T) (p < .002). In 119 observations in 20 animal experiments, the rank correlation between VFT and AEMI(QRS) was − .30 (p < .001), with that between VFT and AEMI(ST-T) being −.55 (p < .0001). In a double-blind pilot clinical trial consisting of 23 studies in 19 patients, the result of electrophysiologic testing was used as an independent measure of cardiac electrical stability. Alternation in waveform morphology identified the inducible patient population with a sensitivity of 92%, a positive predictivity of 70%, and a specificity of 50% (p < .05). We conclude that analysis of subtle beat-to-beat variability in electrocardiographic morphology may provide a noninvasive measure of cardiac electrical stability.

ISSN:0009-7322    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

Previously, we have demonstrated distinguishing features in the fast Fourier transform (FFT) of signal-averaged electrocardiograms (ECGs) obtained during sinus rhythm in the absence of bundle branch block that differentiate patients with from those without sustained ventricular tachycardia (VT). The ECGs during sinus rhythm from many patients with sustained VT, however, exhibit intraventricular conduction abnormalities. Accordingly, this study was performed to determine whether the presence of bundle branch block during sinus rhythm precluded accurate identification of patients with sustained VT. Studies were performed in 28 normal subjects (group I) and 141 patients with organic heart disease grouped according to clinical characteristics. Group II comprised 40 patients without VT in whom the QRS duration during sinus rhythm was less than 120 msec. Group III included 21 patients without VT in whom the QRS duration during sinus rhythm was 120 msec or greater. Group IV comprised 43 patients with sustained VT having ECGs during sinus rhythm with QRS durations less than 120 msec. Group V included 37 patients with sustained VT in whom the QRS duration during sinus rhythm was 120 msec or greater. FFTs of the terminal QRS and ST segment of signal-averaged X, Y, and Z ECGs were computed. Transformed data were expressed as an FFT magnitude and the relative contribution and peak magnitudes of 20 to 50 Hz frequencies determined after first demonstrating that this FFT method was more appropriate, when compared with the energy spectrum, for analyzing ECG signals having a broad range of ST segment durations. Studies were performed first in normal subjects; the range of normal FFT magnitudes was defined and the results were then applied to patients in groups II to V. The FFT magnitude was abnormal in 4% of normal subjects, 20% of patients in group II, and 19% of those in group III. Among patients with VT, the FFT was abnormal in 91% of those with ECGs having a QRS duration less than 120 msec (group IV) and 95% of those with ECGs during sinus rhythm having a QRS duration of 120 msec or greater (group V). Results demonstrate that differentiation of patients with and without VT by this approach is not affected by the presence of bundle branch block. Thus the risk for developing sustained VT can be defined accurately in patients with bundle branch block during sinus rhythm.

ISSN:0009-7322    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

A new operative technique of sequential map-guided subendocardial resection (SER) was used in 45 consecutive patients for the treatment of sustained ventricular tachycardia due to coronary artery disease. This technique is characterized by map-guided SER or cryothermic ablation during normothermic cardiopulmonary bypass, followed by repeated sequences of programmed stimulation to assess adequacy of resection. The patients' mean age was 59 ± 10 years and the mean left ventricular ejection fraction was 34 ± 12%. Twenty-five (56%) patients had a history of myocardial infarction within the previous 2 months. After ventriculotomy, 34 patients (76%) had inducible monomorphic ventricular tachycardia. These patients underwent repeated sequences of ventricular tachycardia induction and mapping during normothermic bypass followed by successive SER or cryothermic ablation until sustained monomorphic ventricular tachycardia was no longer inducible. Twenty-seven patients had a total of 60 discrete, mappable tachycardias induced and seven patients had 10 discrete tachycardias that were too fast to accurately map. In the remaining 11 patients, no ventricular tachycardia was inducible after ventriculotomy and SER, which included all visually identifiable scar, was performed. The mean cardiopulmonary bypass time was 102 ± 27 min. Forty-one of 45 patients (91%) survived to hospital discharge, and 35 of 41 patients (85%) had no inducible ventricular tachycardia at postoperative electrophysiologic evaluation performed in the absence of all antiarrhythmic drugs. The remaining six patients had no inducible ventricular tachycardia with drug therapy. All four operative nonsurvivors had refractory cardiac collapse preoperatively. Over 19 ± 12 months of follow-up, there were four sudden cardiac deaths and no nonfatal recurrences of ventricular tachycardia. There were seven additional cardiac deaths. Actuarial cardiac survival was 0.57, and freedom from arrhythmic events was 0.76 at 42 months. Thus, in the absence of cardiogenic shock, the technique of sequential map-guided SER achieves: (1) a high operative survival with acceptable perfusion times, (2) excellent long-term arrhythmia control, and (3) survival comparable to that in patients with similar left ventricular function and no history of ventricular tachyarrhythmia.

ISSN:0009-7322    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

We assessed thromboxane biosynthesis as an index of platelet activation in 6 patients with acute myocardial infarction receiving intravenous streptokinase. Urinary 2, 3-dinor-thromboxane B2and plasma 11 −dehydro-thromboxane B2, major enzymatic metabolites of thromboxane A2, were markedly increased after intravenous streptokinase (11,063 ± 2758 pg/mg creatinine and 33 ± 10 pg/ml, respectively) compared with levels in patients not receiving thrombolytic therapy (502 ± 89 pg/mg creatinine and 3 ± 0.7 pg/ml). Prostacyclin biosynthesis also increased markedly after streptokinase coincident with the increase in thromboxane A2formation. Administration of aspirin between the time of onset of coronary thrombosis and reperfusion both in man and in a canine preparation demonstrated that this reflected thromboxane biosynthesis de novo and not metabolism of preformed inactive thromboxane B2washed out from the coronary circulation. Since the platelet is the major source of thromboxane A2, these findings suggest that there is marked platelet activation after coronary thrombolysis with streptokinase. Studies in vitro demonstrated that streptokinase enhanced platelet activation in a dose-dependent manner, resulting in the secondary release of thromboxane A2. The increase in platelet activation and thromboxane A2biosynthesis may limit the therapeutic effect of intravenous streptokinase in acute myocardial infarction.

ISSN:0009-7322    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

Two hundred and sixteen patients with acute myocardial infarction were treated with immediate infusion of high-dose (1.5 million units) intravenous streptokinase followed by emergency coronary angioplasty. The infarct lesion was crossed and dilated in 99% and persistent coronary perfusion after the procedure was achieved in 90% (including 3% with significant residual stenosis). Total in-hospital mortality was 12%. Multivariable analysis showed a higher hospital mortality with cardiogenic shock (41% vs 5% without shock), older age, lower left ventricular ejection fraction, and female sex. Final patency of the infarct-related vessel was determined by follow-up in-hospital cardiac catheterization. Coronary reocclusion occurred in 11% (symptomatic in 7%, treated with emergency angioplasty or bypass surgery; silent in 4%, treated medically). Of the surviving patients with successful initial establishment of infarct vessel patency, 94% were discharged from the hospital with an open infarct artery or a bypass graft to the infarct vessel. There was significant improvement in both ejection fraction (44% to 49%; p < .0001) and regional wall motion in the infarct zone (−3.0 SD to −2.4 SD; p < .0001) among patients with persistent coronary perfusion and insignificant residual stenosis at the time of the follow-up cardiac catheterization. Thus, a treatment strategy for acute myocardial infarction that includes immediate administration of streptokinase followed by emergency coronary angioplasty, and coronary bypass surgery when necessary, results in a high rate of early and sustained patency of the infarct-related vessel.

ISSN:0009-7322    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

We have tested the feasibility and effectiveness of a 2 year (average 16 ± 7 months) walk/jog exercise program on 36 male orthotopic cardiac transplant patients (21 to 57 years old) seen initially 2 to 23 months after surgery. Comparison of initial exercise test results with those in 45 age-matched normal men showed the patients to have a lesser lean body mass (56 ± 7 vs 63 ± 8 kg, p < .001), with a higher resting heart rate (104 ± 12 vs 77 ± 14 beats/min, p < .001) and systolic (138 ± 16 vs 129 ± 17 mm Hg, p < .001) and diastolic (95 ± 14 vs 84 ± 10 mm Hg, p < .001) blood pressures. Peak power output was less than normal (101 ± 27 vs 219 ± 41 W, p < .001), as was peak heart rate (136 ± 15 vs 176 ± 13 beats/min, p < .001), peak oxygen intake (±O2max) (22 ± 5 vs 34 ± 6 ml±kg±min-1, p < .001), and absolute anaerobic threshold (1.18 ± 0.40 vs 2.04 ± 0.40 liters±min-1, p < .001). Peak ventilatory equivalent was higher (48 ± 9 vs 37 ± 6 1.1-1, p < .001). Cardiac output (Q), as estimated by the CO2rebreathing method, was slightly above normal at rest (p < .01), but below normal at two submaximal work rates. The group's average weekly training distance was 24 km, with eight highly compliant patients progressing to 32 km or more weekly. After training, lean tissue increased (+ 2.4 ± 3.1 kg, p< .001), and resting values were reduced for heart rate (−4 ± 11 beats/min, p < .05), systolic (−13 ± 20 mm Hg, p < .001), and diastolic (−9 ± 17 mm Hg, p < .001) blood pressures. There were significant reductions in submaximal values for minute ventilation (±E), ratings of perceived exertion, and diastolic blood pressure at equivalent workloads. Peak values increased for power output (+49 ± 34 W, p< .001), ±O2max (+ 4.0 ± 6.0 ml±kg±min-1, p< .001), ±E(+ 20 ± 20 1±min-1, p< .001), and heart rate (+13 ± 17 beats/min, p < .001), and decreased for diastolic blood pressure (−8 ± 15 mm Hg, p < .001). In the eight highly compliant patients a greater decrease occurred in resting heart rate (−11 ± 5 beats/min, p < .001) and submaximal heart rate (range 5 to 10 beats/min less at each power output), with a greater increase in peak power output (+68 ± 42 W, p < .001), and ±O2max (+11 ± 6 ml±kg±min-1, p < .001). The slope of the ±/±O2line was unchanged by training. There was no evidence of cardiac reinner vation in any patient. We conclude that exercise rehabilitation is justified because of its ability to increase working capacity and thus quality of life in cardiac transplant patients.

ISSN:0009-7322    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

The effects of physical exercise and normalization of serum lipoproteins on stress-induced myocardial ischemia were studied in 18 patients with coronary artery disease, stable angina pectoris, and mild hypercholesterolemia (total serum cholesterol 242 ± 32 mg/dl). These patients underwent a combined regimen of low-fat/low-cholesterol diet and regular, supervised physical exercise at high intensity for 12 months. At 1 year serum lipoproteins has been lowered to ideal levels (serum cholesterol 202 ± 31 mg/dl, low-density lipoproteins 130 ± 30 mg/dl, very low-density lipoproteins 22 ± 15 mg/dl, serum triglycerides 105 [69 to 304] mg/dl) and physical work capacity was improved by 21% (p < .01). No significant effect was noted on high-density lipoproteins, probably as a result of the low-fat/high-carbohydrate diet. Stress-induced myocardial ischemia, as assessed by thallium-201 scintigraphy, was decreased by 54% (p < .05) despite higher myocardial oxygen consumption. Eighteen patients matched for age and severity of coronary artery disease served as a control group and “usual medical care” was rendered by their private physicians. No significant changes with respect to serum lipoproteins, physical work capacity, maximal rate-pressure product, or stress-induced myocardial ischemia were observed in this group. These data indicate that regular physical exercise at high intensity, lowered body weight, and normalization of serum lipoproteins may alleviate compromised myocardial perfusion during stress.

ISSN:0009-7322    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

ABSTRACT In rats with catheter-induced sterile aortic valve vegetations we studied the efficacy of single-dose amoxicillin and single-dose erythromycin prophylaxis for the prevention of bacterial endocarditis after extractions of periodontally diseased teeth. Endocarditis after extractions occurred in 89% of control animals and was due to group G streptococci, to Staphylococcus aureus, or to both organisms. A single-dose of amoxicillin or erythromycin successfully prevented endocarditis due to these bacterial species. The analysis of the bacteremia (by culturing blood drawn 1 min after extraction on penicillinase-containing blood agar plates) indicated that amoxicillin did not influence the incidence or the magnitude of circulating group G streptococci and S. aureus, while erythromycin apparently suppressed them. However, when care was taken to eliminate blood erythromycin by a lysis-centrifugation process, the incidence and magnitude of bacteremia after erythromycin prophylaxis was similar to that in control rats. We conclude that single doses of amoxicillin and erythromycin successfully prevent experimental endocarditis after dental extractions. Since this prophylaxis was operative by mechanisms other than the prevention of the circulation of bacteria before seeding the valvular vegetations, it suggests that recommendations for prevention of bacterial endocarditis should not be aimed only at providing adequate antibiotic blood levels to suppress the bacteremia produced by the invasive procedure.

ISSN:0009-7322    

出版商:OVID    

年代:1988

数据来源: OVID