摘要:

BackgroundWe developed the first biplane transesophageal echocardiography (TEE) probe with two orthogonal transducers, allowing synchronous side-by-side displays of the heart on a monitor TV, and compared its diagnostic value with that of conventional single-plane TEE using commercially available Doppler equipment in 200 consecutive patients intraoperatively, perioperatively, or on an outpatient basis.Methods and ResultsInsertion was easy, except in one patient with a mediastinal tumor, and no complications were encountered. Both transverse and longitudinal scans allowed correct identification of true and false lumina in all 30 aortic dissection examinations, but longitudinal scanning was slightly superior in detecting types I and M entry sites. Three entries that were not detected by transverse scanning (two of DeBakey type I and one of type III) were visualized by longitudinal scanning. Among 37 cases of mitral regurgitation (MR), longitudinal scans were significantly superior (p< 0.05) in revealing multiple jets (nine compared with two with transverse scanning). Although both planes yielded almost identical mean values for the maximum jet areas, a difference of over 50% in jet area size on the two planes was observed in 19 cases. The measured jet areas showed significant correlation with the angiographic MR grading, especially for the larger of the biplane measurements (p< 0.01), and different grades showed little overlap. Longitudinal images increased the acoustic window of the heart and aorta from the esophagus. Moreover, longitudinal scanning provided good visualization of both ventricular outflow tracts, the ascending aorta, main pulmonary artery, and superior vena cava.ConclusionsThis modality greatly facilitates a three-dimensional comprehension of cardiovascular lesions and flow dynamics, especially in aortic dissection and MR, and its safety was demonstrated. Our data demonstrate the usefulness of this new technique in comparison with conventional single-plane TEE.

ISSN:0009-7322    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

BackgroundThe ability of transesophageal color Doppler echocardiography to provide high-resolution images of both cardiac structure and blood flow in real time is advantageous for many clinical purposes. This study was performed to determine the utility of the regurgitant jet width at its origin measured by transesophageal Doppler color flow imaging in the assessment of severity of mitral regurgitation.Methods and ResultsSixty-three consecutive patients with mitral regurgitation underwent transesophageal color Doppler examination, and the diameter of regurgitant jet at its origin was measured. Both right and left cardiac catheterizations were performed within 24 hours of Doppler studies, and angiographic grading of mitral regurgitation and regurgitant stroke volume were evaluated. There was a close relation between the jet diameter at its origin measured by transesophageal Doppler color flow imaging and the angiographic grade of mitral regurgitation (r=0.86,p< 0.001). Ajet diameter of 5.5 mm or more identified severe mitral regurgitation (grade III or IV) with a sensitivity of 92%, specificity of 92%, and positive and negative predictive values of 88% and 95%, respectively. In 31 patients with isolated mitral regurgitation, the jet diameter correlated well with the regurgitant stroke volume determined by a combined hemodynamic-angiographic method (r=0.85,p< 0.001). A jet diameter of 5.5 mm or more identified a regurgitant stroke volume of 60 ml or more with a sensitivity of 88%, specificity of 93%, and positive and negative predictive values of 94% and 87%, respectively.ConclusionsThe regurgitant jet width at its origin measured by transesophageal Doppler color flow imaging provides a simple and useful method of measuring the severity of mitral regurgitation, and it may allow differentiation between mild and severe mitral regurgitation.

ISSN:0009-7322    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

BackgroundThrombolysis has altered treatment of acute myocardial infarction (AMI). Therefore, reevaluation of predictors of outcome and treatment strategies is appropriate.Methods and ResultsClinical variables collected prospectively for the 3,339 patients of the Thrombolysis in Myocardial Infarction II study were analyzed retrospectively to identify predictors of clinical events at 42 days and earlier and to identify subgroups in which an invasive or conservative strategy might be superior. Pulmonary edema/cardiogenic shock presented as the strongest independent correlate with death (relative risk, 6.0). In two subgroups, mortality differed between the invasive and conservative strategies: 1) Patients with versus without prior AMI had a higher mortality in the conservative strategy (11.5% versus 3.5%,p< 0.001); in the invasive strategy, the mortality rates were similar (6.0% and 5.1%). 2) Patients with diabetes mellitus and no prior AMI had a higher mortality in the invasive than in the conservative strategy (14.8% versus 4.2%,p< 0.001). Reinfarction was not independently correlated with baseline characteristics except with history of angina (relative risk, 1.9). Mortality was lower in current smokers and ex-smokers versus never-smokers (3.6% and 4.8% versus 8.0%,p< 0.001). Current smokers had a lower risk profile (p< 0.001), including age, pulmonary edema/cardiogenic shock, history of hypertension, and diabetes. The rate of reinfarction was lower in current smokers versus ex-smokers and never-smokers (4.6% versus 8.3% and 8.8%,p< 0.001). “Not current smoker” was an independent correlate with reinfarction (relative risk, 1.9). The coronary anatomy did not differ among the current smokers, ex-smokers, and never-smokers.ConclusionsThe strong independent correlation of pulmonary edema/cardiogenic shock with death suggests that thrombolysis is not sufficient to improve survival in these patients. The higher mortality in patients with versus without prior AMI in the conservative strategy suggests that early catheterization and revascularization of these patients might be beneficial. Conversely, the higher mortality in diabetics without prior AMI in the invasive than in the conservative strategy suggests that early aggressive management might not be suitable in this subgroup except for clinical indications. Reinfarction was not predictable by clinical variables except by history of angina. The finding that “not current smoker” was an independent correlate with reinfarction was unexpected.

ISSN:0009-7322    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

BackgroundAging is associated with an increased risk of women dying from coronary heart disease as well as from all causes combined. Alterations in the major biological risk factors for early coronary heart disease and all-cause mortality are frequently seen in aging.Methods and ResultsThe present investigation tested the hypothesis that high levels of physical activity could protect against age-associated changes in biological risk factor levels. In the Healthy Women Study, 507 women were evaluated at study entry and 3 years later. Weekly physical activity level was measured at each examination via the Paffenbarger Physical Activity Questionnaire. During the 3-year period, women increased significantly in weight, blood pressure, levels of total and low-density lipoprotein cholesterol, triglycerides, and insulin and decreased significantly in levels of total high-density lipoprotein cholesterol (HDL-C) and HDL2-C.ConclusionsConsistent with the study hypothesis, women who reported higher levels of activity at baseline had less weight gain over time. Furthermore, women who increased their activity during the 3-year interval had the smallest increases in weight and tended to have the smallest decreases in total HDL-C and HDL2-C. The changes in lipids due to activity were largely independent of changes in body weight.

ISSN:0009-7322    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

BackgroundPremature stimuli can cause ventricular fibrillation (VF) during electrophysiological testing. The electrophysiological correlations associated with the onset ofVF were evaluated in 40 patients who had this rhythm induced during programmed ventricular stimulation. These parameters were compared with those observed in 51 patients who had inducible sustained monomorphic ventricular tachycardia (VT) and 45 patients who had no inducible sustained ventricular tachyarrhythmias.Methods and Resut.Shortest premature coupling intervals for S2, S3, and S4 at induction of tachycardia or before achieving refractoriness, corresponding conduction latencies (defined as the time from the premature stimulus to the upstroke of the depolarization wave front recorded 35 mm away from the stimulation site), and ventricular activation times (defined as the time from the premature stimulus to the end of the depolanzation wave) were compared. The mean coupling intervals were longest in the inducible VT patients: 300±30, 254±57, and 228±32 msec for S2, S3, and S4, respectively. In the inducible VF group, the coupling intervals were 260±37, 208±20, and 213±30 msec. In the group with no inducible VT or VF, these coupling intervals were 251±24 (p< 0.01 versus inducible VT group), 209±27 (p< 0.001 versus inducible VT group), and 194±21 msec (p< 0.05 versus inducible VT and VF groups). The coupling interval of the last premature extrastimulus was above 200 msec in 70% of the patients in whom VF was induced. The largest increases in latency and activation times were recorded in patients in whom VF was induced. The cumulative increase in latency, defined as increased conduction time from baseline, summed for all the premature stimuli was also the greatest at initiation of VF. In contrast, the smallest increases in these parameters were noted in the patients with no inducible VT or VF. Measurements of total activation time yielded similar results as those recorded for latencies. The most important parameters distinguishing the VT patient population from the other two groups were the low ejection fractions and the longer coupling intervals at which VT was induced, whereas in the VF group, the most important discriminating factor was cumulative activation time. Sixty-three percent of the inducible VF patients presented with abnormal hearts (myocardial infarction or cardiomyopathy), whereas 88% of the inducible VT patients had abnormal hearts. In contrast, only 25% of the patients in whom no arrhythmia was induced presented with abnormal hearts. Mean ejection fraction was 32±15% for the inducible VT group, 45±13%*for the inducible VF group, and 51±17%*for patients with no inducible VTIVF (*p< 0.001 versus VT).ConclusionsThe results suggest that 1) initiation of ventricular tachycardia during programmed ventricular stimulation occurs with minimal conduction latency; 2) because of the large overlap in coupling intervals where VF or VT were induced, a single coupling interval cannot be recommended to adequately separate these groups; and 3) induction of VF was preceded by increased latency and prolongation of the local activation time. These parameters should not be allowed to prolong if VF is to be avoided during programmed stimulation. In addition, 4) the initiation of VF during electrophysiological studies is often associated with the presence of structural heart disease; such structural disease may promote conduction latency and the development of VF.

ISSN:0009-7322    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

BackgroundTo determine the relation of post-percutaneous transluminal coronary angioplasty (PTCA) restenosis to serum lipid fractions and to circulating levels of endogenous tissue plasminogen activator (t-PA) and its rapid inhibitor (PAI-1), 68 patients with coronary artery disease who underwent a successful PTCA were studied.Methods and ResultsDuring a mean follow-up of 9 months (range, 7–11 months), 28 (41%) patients developed restenosis. A low high density lipoprotein (HDL) cholesterol level was independently and strongly related to both the risk of restenosis (p< 0.001) and to the time of restenosis (p= 0.03). The mean HDL cholesterol level was 33±12 mg% in the restenosis group compared with 45±12 mg% in the nonrestenosis group (p< 0.001). Restenosis developed in 22 of 34 (64%) patients with an HDL cholesterol ≤40 mg% compared with six of 34 (17%) patients with an HDL cholesterol >40 mg% (p< 0.002). The only other variable that was significantly related to restenosis was a low PAI-1 level (p= 0.04).ConclusionsThe strong relation between a low HDL cholesterol level and the risk of restenosis suggests that lipid fractions could be important in the pathogenesis and prevention of restenosis.

ISSN:0009-7322    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

BackgroundTo examine the relation of plasma lipoproteins to the proliferative response after arterial injury in humans, we examined the plasma lipid, lipoprotein, and apoprotein levels of 20 patients with early recurrent stenosis caused by intimal hyperplasia after carotid endarterectomy. These were compared with 20 controls who had no evidence of recurrent stenosis by duplex ultrasound scanning.Methods and ResultsBy univariate analysis, the reoperated patients had higher levels of plasma cholesterol (251 versus 225 mg/dl,p< 0.05), total triglycerides (173 versus 105 mg/dl,p< 0.03), and low density lipoprotein (LDL) apoprotein B (99.8 versus 77.2 mg/dl,p< 0.003). The ratio of cholesterol to apoprotein B in LDL was lower in patients with restenosis (p< 0.04), suggesting LDL of smaller diameter. High density lipoprotein (HDL) cholesterol level was reduced (45 versus 55 mg/dl,p< 0.01) in patients with restenosis. With statistical adjustment for the correlations between these variables by multivariate analysis, both LDL apoprotein B and HDL cholesterol were independent predictors of the risk of restenosis. Ten patients with restenosis but only two controls had one or two apolipoprotein E4 alleles.ConclusionsElevated lipid levels usually associated with an increased risk of atherosclerosis may predispose patients to an increased incidence of intimal hyperplasia after endarterectomy.

ISSN:0009-7322    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

BackgroundLovastatin produces consistent dose-related reductions in plasma levels of low density lipoprotein (LDL) cholesterol along with variable decreases in triglycerides and increases in high density lipoprotein (HDL) cholesterol. Patient characteristics from the Expanded Clinical Evaluation of Lovastatin (EXCEL) study were examined to determine their association with the magnitude of lovastatin-induced changes in these lipids and lipoproteins.Methods and ResultsAfter a baseline period consisting of dietary therapy, 8,245 patients with moderate hypercholesterolemia were randomized to five groups that received 48 weeks of treatment with either placebo or daily doses of lovastatin ranging from 20 to 80 mg. By use of linear statistical models, 20 different patient characteristics were examined for modification of the dose-dependent responses observed. For LDL cholesterol, the following were associated with enhanced lowering (p< 0.05; percent changes are placebo-corrected, adjusted mean changes from baseline for the 80-mg/day lovastatin group): full drug compliance (−41.9%) versus 80% compliance (−20.3%); an age of 65 (−43.4%) versus 45 years (−38.1%) for women; white race (−40.9%) versus black race (−38.0%); and 4.5-kg weight gain (−42.6%) versus 4.5-kg weight loss (−37.9%). Similar relations for enhanced triglyceride lowering were found with older age and weight gain. Patients with initially low HDL cholesterol (<0.91 mmol/l) and high triglycerides (>2.26 mmol/l) had enhanced responses for these parameters: placebo-corrected percent changes at 80 mg/day were −27.4% for triglycerides and +12.3% for HDL cholesterol.ConclusionsOverall, patient characteristics had very little impact of clinical importance on the dose-dependent LDL cholesterol lowering found with lovastatin. In patients with initially high levels of triglycerides and low levels of HDL cholesterol, the elevation of HDL cholesterol produced by lovastatin appears to be enhanced.

ISSN:0009-7322    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

BackgroundThe outcomes of patients treated with implantable defibrillators were compared between patients with left ventricular ejection fraction ≥30% and <30%.Methods and ResultsOf 68 consecutive patients treated with implantable defibrillators, 40 patients (group 1) had left ventricular ejection fraction ≥30%, and 28 patients (group 2) had left ventricular ejection fraction <30%. Sudden death, surgical mortality, nonsudden arrhythmia-related death (death within 24 hours after an arrhythmic event despite initial termination of the arrhythmia by the implantable defibrillator), total arrhythmia-related death (including sudden death, surgical death, and nonsudden arrhythmia-related death), and total cardiac death were compared between the two groups. Surgical mortality was 4.4% (09% in group 1, 11% in group 2). During the follow-up of 31±27 months, actuarial survival rates free of events were 97%, 97%, and 97% in group 1 and 96%, 91%, and 82% in group 2 at 12, 24, and 36 months, respectively, for sudden death (p= NS); 97%, 97%, and 97% in group 1 and 85%, 81%, and 72% in group 2 at 12, 24, and 36 months, respectively, for sudden death and surgical mortality (p< 0.05); 97%, 97%, and 97% in group 1 and 82%, 78%, and 709% in group 2 at 12, 24, and 36 months, respectively, for total arrhythmia-related death (p< 0.05); and 95%, 95%, and 95% in group 1 and 82%, 69%, and 57% in group 2 at 12, 24, and 36 months, respectively, for total cardiac death (p< 0.05). Four (57%) of seven nonsudden cardiac deaths during the initial 36-month follow-up period were causally related to arrhythmia (three surgical deaths and one arrhythmia-related nonsudden death).ConclusionsThe outcome of patients treated with implantable defibrillators is strongly influenced by the degree of left ventricular dysfunction. In group 1 patients, surgical mortality, sudden death, and total cardiac death are rare. In group 2, sudden death rate may not be markedly different from that of group 1 patients. However, the risk of therapy (surgical mortality) is high. Many nonsudden cardiac deaths are causally related to arrhythmia (surgical mortality or nonsudden arrhythmia-related death). Therefore, the survival rate free of total arrhythmia-related death is significantly lower in group 2 (70% versus 97% in group 1 at 3 years). Further studies are needed to determine the roles of defibrillator therapy and other therapies in various clinical settings.

ISSN:0009-7322    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

BackgroundIn animals, parasympathetic nerve fibers that innervate the sinoatrial node can be selectively stimulated to increase atrial cycle length. These nerve fibers course through an epicardial fat pad at the margin of the right superior pulmonary vein, the superior vena cava, and the right atrium. We hypothesized that similar nerves exist and can be selectively stimulated in humans.Methods and ResultsMicroscopic examination of fat pads excised from the margin of the right superior pulmonary vein, the superior vena cava, and the right atrium during two human autopsies revealed the presence of nerve fibers and ganglia. We electrically stimulated this epicardial fat pad in 16 patients during cardiac surgery. The fat pads were stimulated with continuous-pulse trains for 15 seconds via a hand-held bipolar electrode using constant current (10–15 mA), constant pulse width (0.02–0.05 msec), and at 6.6, 10, 20, 25, and 30 Hz. The mean atrial cycle length ±1 SEM increased from 734±34 msec at baseline to a maximum of 823±61 msec at 6.6 Hz, 1,167±125 msec at 10 Hz, 1,734±281 msec at 20 Hz, 2,993±661 msec at 25 Hz, and 2,461±668 msec at 30 Hz during nerve stimulation. Linear regression analysis showed that the response of atrial cycle length to sinoatrial parasympathetic nerve stimulation was frequency dependent. The maximum response and complete decay of the response occurred within 4–8 seconds of initiation or termination of sinoatrial parasympathetic nerve stimulation. Atrioventricular conduction time and the PR interval did not change during sinoatrial parasympathetic nerve stimulation, even when the atria were paced at the baseline heart rate.ConclusionsElectrical stimulation of parasympathetic nerve fibers in a fat pad near the sinoatrial node increased atrial cycle length without affecting atrioventricular nodal conduction. This is the first study in which such nerve fibers that innervate the sinoatrial node have been selectively stimulated in humans.

ISSN:0009-7322    

出版商:OVID    

年代:1992

数据来源: OVID