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The importance of the contribution of atrial systole to ventricular filling in mitral stenosis is controversial. The cause of reduced cardiac output following the onset of atrial fibrillation may be due to an increased heart rate, a loss of booster pump function, or both. | 10.1161/01.cir.84.4.1469
| Atrial contribution to ventricular filling in mitral stenosis. | Circulation |
We studied the atrial contribution to filling under a variety of conditions by combining noninvasive studies of patients with computer modeling. Thirty patients in sinus rhythm with mild-to-severe stenosis were studied with two-dimensional and Doppler echocardiography for measurement of mitral flow velocity and mitral ... | 10.1161/01.cir.84.4.1469
| Atrial contribution to ventricular filling in mitral stenosis. | Circulation |
The atrial booster pump contributes less to ventricular filling in mitral stenosis than in the normal heart, and the loss of atrial pump function is less important than the effect of increasing heart rate as the cause of decompensation during atrial fibrillation. | 10.1161/01.cir.84.4.1469
| Atrial contribution to ventricular filling in mitral stenosis. | Circulation |
Imaging of the flow convergence region (FCR) proximal to a regurgitant orifice has been shown to provide a method for quantifying the regurgitant flow rate. According to the continuity principle, the FCR is constituted by concentric hemispheric isovelocity surfaces centered at the orifice. The flow rate is constant acr... | 10.1161/01.cir.84.4.1481
| A new method for quantitation of mitral regurgitation based on color flow Doppler imaging of flow convergence proximal to regurgitant orifice. | Circulation |
We studied 52 consecutive patients with mitral regurgitation (mean age, 49 years; age range, 21-66 years) verified by left ventricular angiography using color flow mapping. The FCR r was measured as the distance between the first aliasing limit--at a Nyquist limit obtained by zero-shifting the velocity cutoff to 38 cm/... | 10.1161/01.cir.84.4.1481
| A new method for quantitation of mitral regurgitation based on color flow Doppler imaging of flow convergence proximal to regurgitant orifice. | Circulation |
Color flow Doppler provides new velocity information about the proximal FCR in patients with mitral regurgitation. According to the continuity principle, the maximal instantaneous regurgitant flow rate, obtained with the FCR method, may provide a quantitative estimate of the severity of mitral regurgitation, which is r... | 10.1161/01.cir.84.4.1481
| A new method for quantitation of mitral regurgitation based on color flow Doppler imaging of flow convergence proximal to regurgitant orifice. | Circulation |
This study was designed to evaluate the effect of severe peripheral arterial insufficiency on carnitine concentrations and carnitine acetyltransferase and palmitoyltransferase activities in the ischemic skeletal muscles of patients with severe peripheral vascular disease. | 10.1161/01.cir.84.4.1490
| Muscle carnitine deficiency in patients with severe peripheral vascular disease. | Circulation |
Nine biopsy specimens of ischemic muscles were obtained from five patients undergoing reconstructive vascular surgery. Biopsies from 35 normal subjects served as controls. Ischemic muscles showed a significant reduction in total carnitine from the control value of 20.9 +/- 5.2 to 11.6 +/- 6.2 nmol/mg noncollagen protei... | 10.1161/01.cir.84.4.1490
| Muscle carnitine deficiency in patients with severe peripheral vascular disease. | Circulation |
05 nmol/min/mg noncollagen protein in the ischemic muscles and 0.28 +/- 0.07 nmol/min/mg noncollagen protein in controls). Carnitine, acylcarnitines, and enzyme activities were also measured in the ischemic muscles in four additional patients 2 days after intravenous administration of L-propionylcarnitine (1.5 g as a s... | 10.1161/01.cir.84.4.1490
| Muscle carnitine deficiency in patients with severe peripheral vascular disease. | Circulation |
Demonstration of carnitine deficiency in severe peripheral vascular disease substantiates previous findings showing the efficacy of carnitine supplementation to ischemic muscles. Furthermore, the feasibility of restoring carnitine homeostasis with L-propionylcarnitine provides the basis for clinical trials aimed at ass... | 10.1161/01.cir.84.4.1490
| Muscle carnitine deficiency in patients with severe peripheral vascular disease. | Circulation |
Regional nonuniformity has been suggested to be closely related to left ventricular (LV) relaxation in diseased heart. The purpose of the present study was to assess LV global and regional relaxation in patients with nonobstructive hypertrophic cardiomyopathy (HCM). | 10.1161/01.cir.84.4.1496
| Left ventricular regional relaxation and its nonuniformity in hypertrophic nonobstructive cardiomyopathy. | Circulation |
Left ventriculography was conducted simultaneously with pressure micromanometry in 10 normal control subjects and 11 patients with nonobstructive HCM. LV silhouettes in the right anterior oblique projection were divided into eight regions, and regional wall stress during isovolumic relaxation was computed for six regio... | 10.1161/01.cir.84.4.1496
| Left ventricular regional relaxation and its nonuniformity in hypertrophic nonobstructive cardiomyopathy. | Circulation |
16 versus 2.15 +/- 0.14, p less than 0.01). These findings suggest that there is impaired LV relaxation in HCM patients. End-systolic regional wall stress was lower, and the time constant of regional stress decrease (Tst) was prolonged for each region in HCM patients compared with control subjects. In the HCM group, Ts... | 10.1161/01.cir.84.4.1496
| Left ventricular regional relaxation and its nonuniformity in hypertrophic nonobstructive cardiomyopathy. | Circulation |
Significant correlations existed between the coefficients of variation for Tst and Tp (r = 0.80, p less than 0.01), IRT (r = 0.79, p less than 0.01), and dP/dt(20/60) (r = -0.67, p less than 0.05) in the HCM group. Thus, regional nonuniformity is closely related to the impairment of LV relaxation in HCM. | 10.1161/01.cir.84.4.1496
| Left ventricular regional relaxation and its nonuniformity in hypertrophic nonobstructive cardiomyopathy. | Circulation |
In myocardial infarction patients, heart rate-adjusted QT interval (QTc), an electrocardiographic indicator of sympathetic balance, is prognostic for survival. | 10.1161/01.cir.84.4.1516
| QT interval prolongation predicts cardiovascular mortality in an apparently healthy population. | Circulation |
In a 28-year follow-up, the association between QTc and all-cause, cardiovascular, and ischemic heart disease mortality was studied in a population of 3,091 apparently healthy Dutch civil servants and their spouses, aged 40-65 years, who participated in a medical examination during 1953-1954. Moderate (QTc, 420-440 mse... | 10.1161/01.cir.84.4.1516
| QT interval prolongation predicts cardiovascular mortality in an apparently healthy population. | Circulation |
Our results suggest that QTc contributes independently to cardiovascular risk. If autonomic imbalance is an important mechanism, it might be speculated that changes in life-style (e.g., with regard to physical exercise and smoking) may have a preventive impact. | 10.1161/01.cir.84.4.1516
| QT interval prolongation predicts cardiovascular mortality in an apparently healthy population. | Circulation |
From the international long QT syndrome (LQTS) study, 30 patients with corrected QT interval (QTc) of more than 0.44 second 1/2 were identified who had permanent pacemakers implanted for management of recurrent syncope or aborted cardiac arrest.
Pacemakers were implanted on average 7 years after the onset of ... | 10.1161/01.cir.84.4.1524
| Efficacy of permanent pacing in the management of high-risk patients with long QT syndrome. | Circulation |
The beneficial effects of pacing in high-risk LQTS patients probably relate to the prevention of bradycardia, pauses, and the shortening of long QT intervals--factors that are known to be arrhythmogenic in this syndrome. Permanent cardiac pacing reduces the rate of recurrent syncopal events in high-risk LQTS patients, ... | 10.1161/01.cir.84.4.1524
| Efficacy of permanent pacing in the management of high-risk patients with long QT syndrome. | Circulation |
The idiopathic long QT syndrome (LQTS) is characterized by electrocardiographic abnormalities and by a high incidence of lethal arrhythmias. The present case/control study demonstrates the frequent occurrence of unusual and specific ventricular wall motion abnormalities in LQTS and their association with history of syn... | 10.1161/01.cir.84.4.1530
| Unsuspected echocardiographic abnormality in the long QT syndrome. Diagnostic, prognostic, and pathogenetic implications. | Circulation |
Two new measurements were developed to assess quantitatively the abnormalities observed. The first, Th1/2, is an index of the rapidity of the early contraction phase; the second, TSTh, is an index of the presence of a slow movement in the late thickening phase. Th1/2 was smaller in LQTS patients (15.0 +/- 4.1 versus 19... | 10.1161/01.cir.84.4.1530
| Unsuspected echocardiographic abnormality in the long QT syndrome. Diagnostic, prognostic, and pathogenetic implications. | Circulation |
A peculiar double peak pattern of late thickening was present in 11 patients and in no controls. These abnormalities were more frequent in symptomatic than in asymptomatic patients (20 of 26, 77%, versus three of 16, 19%, p less than 0.005; relative risk, 2.75). They were not affected by beta-blockade or by left cardia... | 10.1161/01.cir.84.4.1530
| Unsuspected echocardiographic abnormality in the long QT syndrome. Diagnostic, prognostic, and pathogenetic implications. | Circulation |
This study demonstrates a previously unsuspected abnormality in the ventricular contraction pattern of LQTS patients and, for the first time, provides evidence that a noninvasively detected cardiac abnormality is associated with a higher risk for syncope/cardiac arrest. The experimental reproduction of this echocardiog... | 10.1161/01.cir.84.4.1530
| Unsuspected echocardiographic abnormality in the long QT syndrome. Diagnostic, prognostic, and pathogenetic implications. | Circulation |
During a 2.9-year period, 11 patients developed polymorphous ventricular tachycardia 1-13 days after acute anterior (seven patients) or inferior (four patients) myocardial infarction. None of the 11 patients had sinus bradycardia (mean heart rate, 90 +/- 23 beats/min), but three had a sinus pause immediately before the... | 10.1161/01.cir.84.4.1543
| Polymorphous ventricular tachycardia associated with acute myocardial infarction. | Circulation |
Immediately before the onset of polymorphous ventricular tachycardia, symptoms and/or electrocardiographic changes consistent with recurrent myocardial ischemia occurred in nine of 11 patients. One patient died before drug therapy could be initiated. Lidocaine was used in 10 patients and proved to be effective in only ... | 10.1161/01.cir.84.4.1543
| Polymorphous ventricular tachycardia associated with acute myocardial infarction. | Circulation |
Post-myocardial infarction polymorphous ventricular tachycardia is not consistently related to an abnormally long QT interval, sinus bradycardia, preceding sinus pauses, or electrolyte abnormalities. This arrhythmia has a variable response to class I antiarrhythmics but may be suppressed by intravenous amiodarone thera... | 10.1161/01.cir.84.4.1543
| Polymorphous ventricular tachycardia associated with acute myocardial infarction. | Circulation |
This study was designed to determine the controlled effects of a short-term exercise rehabilitation program on patients with moderate-to-severe left ventricular dysfunction after a recent myocardial infarction. | 10.1161/01.cir.84.4.1561
| Randomized 4-week exercise program in patients with impaired left ventricular function. | Circulation |
Thirty-nine male patients 51 +/- 8 years old with a large anterior myocardial infarction less than 10 weeks old were recruited for the study. The patients were randomly assigned to either one of two training or control groups on the basis of their resting ejection fraction: training, less than 30%; control, less than 3... | 10.1161/01.cir.84.4.1561
| Randomized 4-week exercise program in patients with impaired left ventricular function. | Circulation |
It was concluded that in the present study, exercise training had little or no effect on hemodynamic measurements and that the training effects achieved in patients with left ventricular dysfunction are most likely due to corrected impaired vasodilation, not necessarily to cardiac function. The importance of using a co... | 10.1161/01.cir.84.4.1561
| Randomized 4-week exercise program in patients with impaired left ventricular function. | Circulation |
This study was designed to examine the hemodynamic, renal, and hormonal effects of brain natriuretic peptide (BNP) infusion in patients with congestive heart failure (CHF) and in control subjects. | 10.1161/01.cir.84.4.1581
| Hemodynamic, renal, and hormonal responses to brain natriuretic peptide infusion in patients with congestive heart failure. | Circulation |
We infused synthetic human BNP at a rate of 0.1 micrograms/kg/min. BNP infusion decreased pulmonary capillary wedge pressure (control, from 5 +/- 1 to 2 +/- 1 mm Hg, p less than 0.01; CHF, from 21 +/- 3 to 14 +/- 4 mm Hg, p less than 0.05) and systemic vascular resistance (control, from 1,264 +/- 75 to 934 +/- 52 dyne.... | 10.1161/01.cir.84.4.1581
| Hemodynamic, renal, and hormonal responses to brain natriuretic peptide infusion in patients with congestive heart failure. | Circulation |
6 +/- 3.8 to 32.0 +/- 3.9 ml/m2, p less than 0.01). BNP infusion significantly increased urine volume (control, from 2.3 +/- 0.7 to 7.5 +/- 1.9 ml/min; CHF, from 0.8 +/- 0.2 to 5.3 +/- 1.0 ml/min; p less than 0.01, respectively), excretion of sodium (control, from 79.2 +/- 21.6 to 332.8 +/- 70.9 microEq/min; CHF, from ... | 10.1161/01.cir.84.4.1581
| Hemodynamic, renal, and hormonal responses to brain natriuretic peptide infusion in patients with congestive heart failure. | Circulation |
0 microEq/min; p less than 0.01, respectively), and excretion of chloride (control, from 72.5 +/- 18.4 to 256.0 +/- 43.3 microEq/min; CHF, from 74.0 +/- 19.6 to 708.8 +/- 103.3 microEq/min; p less than 0.01, respectively). Urinary excretion of sodium and of chloride in response to BNP infusion was higher in patients wi... | 10.1161/01.cir.84.4.1581
| Hemodynamic, renal, and hormonal responses to brain natriuretic peptide infusion in patients with congestive heart failure. | Circulation |
3 +/- 12.1 to 27.3 +/- 7.1 pg/ml; CHF, from 91.1 +/- 34.3 to 66.3 +/- 27.2 pg/ml; p less than 0.05, respectively). | 10.1161/01.cir.84.4.1581
| Hemodynamic, renal, and hormonal responses to brain natriuretic peptide infusion in patients with congestive heart failure. | Circulation |
We conclude that BNP infusion improves left ventricular function in patients with CHF by vasodilation and prominent natriuretic action. | 10.1161/01.cir.84.4.1581
| Hemodynamic, renal, and hormonal responses to brain natriuretic peptide infusion in patients with congestive heart failure. | Circulation |
Endothelial cells produce a number of substances, collectively termed endothelium-derived relaxing factor (EDRF), that promote local relaxation of vascular smooth muscle. Although studies have demonstrated defects in endothelium-dependent vasodilation in animal models of hypertension, atherosclerosis, and heart failure... | 10.1161/01.cir.84.4.1589
| Endothelium-dependent vasodilation is attenuated in patients with heart failure. | Circulation |
To address the hypothesis that endothelium-dependent vasodilation is attenuated in patients with heart failure, we measured forearm blood flow responses to the intra-arterial administration of methacholine, a known stimulus of EDRF release through muscarinic receptors. In 14 normal subjects, a dosage range of methachol... | 10.1161/01.cir.84.4.1589
| Endothelium-dependent vasodilation is attenuated in patients with heart failure. | Circulation |
31 versus 9.52 +/- 0.60 ml/min/100 ml FAV; p = 0.0003). In a second study, the average difference in forearm blood flow responses between patients with heart failure and normal subjects with methacholine was significantly greater than the average difference between the groups with nitroprusside (4.04 +/- 1.10 versus 2.... | 10.1161/01.cir.84.4.1589
| Endothelium-dependent vasodilation is attenuated in patients with heart failure. | Circulation |
These data suggest that endothelium-dependent vasodilation is attenuated in patients with heart failure. Although the mechanisms of the decreased endothelium-dependent responses in heart failure are not known, this impaired local vasodilation may contribute to abnormalities in vasoconstriction that are characteristic o... | 10.1161/01.cir.84.4.1589
| Endothelium-dependent vasodilation is attenuated in patients with heart failure. | Circulation |
Exertional fatigue, which frequently limits exercise in patients with chronic heart failure, is associated with early anaerobic metabolism in skeletal muscle. The present study was designed to examine the skeletal muscle metabolic response to exercise in this disorder and determine the relation of reduced muscle blood ... | 10.1161/01.cir.84.4.1597
| Altered skeletal muscle metabolic response to exercise in chronic heart failure. Relation to skeletal muscle aerobic enzyme activity. | Circulation |
We evaluated leg blood flow, blood lactate, and skeletal muscle metabolic responses (by vastus lateralis biopsies) during upright bicycle exercise in 11 patients with chronic heart failure (ejection fraction 21 +/- 8%) and nine normal subjects. In patients compared to normal subjects, peak exercise oxygen consumption w... | 10.1161/01.cir.84.4.1597
| Altered skeletal muscle metabolic response to exercise in chronic heart failure. Relation to skeletal muscle aerobic enzyme activity. | Circulation |
04). In patients, leg blood flow was decreased at rest, submaximal, and maximal exercise when compared to normal subjects (all p less than 0.05), and blood lactate accumulation was accelerated. In patients, during submaximal exercise blood lactate levels were not closely related to leg blood flow but were inversely rel... | 10.1161/01.cir.84.4.1597
| Altered skeletal muscle metabolic response to exercise in chronic heart failure. Relation to skeletal muscle aerobic enzyme activity. | Circulation |
The results of the present study suggest that in patients with chronic heart failure reduced aerobic activity in skeletal muscle plays an important role in mediating the early onset of anaerobic metabolism during exercise. Our findings are consistent with the concept that reduced aerobic enzyme activity in skeletal mus... | 10.1161/01.cir.84.4.1597
| Altered skeletal muscle metabolic response to exercise in chronic heart failure. Relation to skeletal muscle aerobic enzyme activity. | Circulation |
This prospective study was designed to test the hypothesis that the assessment of left ventricular systolic function at the time of emergency room (ER) presentation provides valuable diagnostic and prognostic information in patients with cardiac-related symptoms. | 10.1161/01.cir.84.4.1615
| Importance of two-dimensional echocardiographic assessment of left ventricular systolic function in patients presenting to the emergency room with cardiac-related symptoms. | Circulation |
The study is based on a 2-year follow-up of 171 consecutive patients evaluated in the ER for such symptoms. In the course of follow-up, one third of the patients (55 of 171) suffered a major cardiac event. For those with left ventricular systolic dysfunction (LVSD), the age-adjusted rate of early events (occurring with... | 10.1161/01.cir.84.4.1615
| Importance of two-dimensional echocardiographic assessment of left ventricular systolic function in patients presenting to the emergency room with cardiac-related symptoms. | Circulation |
Confounders for late events included advanced age and a history of hypertension. LVSD on two-dimensional echocardiography (2DE) was the only finding associated with early and late events after controlling for other risk factors. In addition, the prediction of these events derived from the combination of historical, cli... | 10.1161/01.cir.84.4.1615
| Importance of two-dimensional echocardiographic assessment of left ventricular systolic function in patients presenting to the emergency room with cardiac-related symptoms. | Circulation |
We conclude that the 2DE assessment of left ventricular systolic function provides valuable diagnostic and prognostic information in subjects presenting to the ER with cardiac-related symptoms. | 10.1161/01.cir.84.4.1615
| Importance of two-dimensional echocardiographic assessment of left ventricular systolic function in patients presenting to the emergency room with cardiac-related symptoms. | Circulation |
Many asymptomatic patients with aorta regurgitation and normal left ventricular systolic function remain clinically stable for many years, but others ultimately develop symptoms or left ventricular dysfunction and require operation. To identify indexes of left ventricular function predictive of symptomatic and function... | 10.1161/01.cir.84.4.1625
| Serial long-term assessment of the natural history of asymptomatic patients with chronic aortic regurgitation and normal left ventricular systolic function. | Circulation |
Serial echocardiographic (average, 7.8 per patient) and radionuclide angiographic (average, 5.0 per patient) studies were obtained over a mean follow-up period of 8 years (range, 2-16 years). By Kaplan-Meier life table analysis, 58 +/- 9% of patients remained asymptomatic with normal ejection fraction at 11 years, an a... | 10.1161/01.cir.84.4.1625
| Serial long-term assessment of the natural history of asymptomatic patients with chronic aortic regurgitation and normal left ventricular systolic function. | Circulation |
05), initial end-systolic dimension (p less than 0.001), and rate of change in end-systolic dimension and rest ejection fraction during serial studies (both p less than 0.05) predicted outcome. | 10.1161/01.cir.84.4.1625
| Serial long-term assessment of the natural history of asymptomatic patients with chronic aortic regurgitation and normal left ventricular systolic function. | Circulation |
Thus, in addition to indexes of left ventricular function determined on initial evaluation, serial long-term changes in systolic function identify patients likely to develop symptoms and require operation. Patients have a higher risk of symptomatic deterioration if there is progressive change in end-systolic dimension ... | 10.1161/01.cir.84.4.1625
| Serial long-term assessment of the natural history of asymptomatic patients with chronic aortic regurgitation and normal left ventricular systolic function. | Circulation |
Late angiographic narrowing has been observed following coronary implantation of the Wallstent. To identify the angiographic variables that predict restenosis within the stented segment, a retrospective study of data from the European Wallstent core laboratory was performed. | 10.1161/01.cir.84.4.1636
| Relative risk analysis of angiographic predictors of restenosis within the coronary Wallstent. | Circulation |
Follow-up angiograms (excluding patients with in-hospital occlusions) were analyzed for 214 lesions in 176 patients (78% restudy rate). The incidence of restenosis within the stented segment was 35% by lesion and 35% by patient for criterion 1 (greater than or equal to 0.72 mm loss in minimal luminal diameter) and 24% ... | 10.1161/01.cir.84.4.1636
| Relative risk analysis of angiographic predictors of restenosis within the coronary Wallstent. | Circulation |
45), and for criterion 2, oversizing by more than 0.70 mm (relative risk, 1.93; 95% CI, 1.13-3.31), bypass grafts (relative risk, 1.62; 95% CI, 0.98-2.66), use of multiple stents/lesion (relative risk, 1.61; 95% CI, 0.97-2.67) and residual diameter stenosis more than 20% post stenting (relative risk, 1.51; 95% CI, 0.91... | 10.1161/01.cir.84.4.1636
| Relative risk analysis of angiographic predictors of restenosis within the coronary Wallstent. | Circulation |
It is concluded that several angiographic variables are significantly associated with late angiographic narrowing after stenting in the coronary arteries. We suggest that stent operators avoid excessive oversizing in the selection of stent diameter and the use of multiple stents per lesion to lessen the risk of late re... | 10.1161/01.cir.84.4.1636
| Relative risk analysis of angiographic predictors of restenosis within the coronary Wallstent. | Circulation |
Recent investigations have shown that cure of patients with symptomatic tachyarrhythmias related to an accessory atrioventricular pathway may be achieved by closed-chest electrode catheter ablation of the accessory connection. Direct current shocks have primarily been used for this purpose, but its applicability is lim... | 10.1161/01.cir.84.4.1644
| Catheter ablation using radiofrequency current to cure symptomatic patients with tachyarrhythmias related to an accessory atrioventricular pathway. | Circulation |
Seventy-three symptomatic patients with Wolff-Parkinson-White syndrome and 19 patients with only retrogradely conducting (concealed) pathways underwent ablative therapy with radiofrequency current. There were 71 accessory pathways located on the left side of the heart (57 free-wall and 14 posteroseptal pathways) and 25... | 10.1161/01.cir.84.4.1644
| Catheter ablation using radiofrequency current to cure symptomatic patients with tachyarrhythmias related to an accessory atrioventricular pathway. | Circulation |
Although the electrophysiological mechanisms underlying self-sustaining atrial fibrillation (AF) are unclear, recent studies suggest that one requirement for reentry, slow conduction, is frequently present in patients with AF. However, these observations limited to paroxysmal AF may not necessarily apply to chronic AF.... | 10.1161/01.cir.84.4.1662
| Electrophysiological properties in chronic lone atrial fibrillation. | Circulation |
Electrophysiological studies were performed after electrocardioversion in 12 patients with chronic lone AF. Atrial enlargement was absent in the patients with AF. Twelve patients without atrial arrhythmias served as the control group. The patients with AF had a higher incidence of sinus nodal dysfunction, a shorter atr... | 10.1161/01.cir.84.4.1662
| Electrophysiological properties in chronic lone atrial fibrillation. | Circulation |
01) and to the coronary sinus (41 +/- 15 msec versus 15 +/- 11 msec, p less than 0.01). The fragmented atrial activity zone was wider in the study group (23 +/- 25 msec) than in control subjects (1.7 +/- 4 msec, p less than 0.02). Repetitive atrial firing was observed in four patients with AF but it was not seen in the... | 10.1161/01.cir.84.4.1662
| Electrophysiological properties in chronic lone atrial fibrillation. | Circulation |
These electrophysiological features, which are manifestations of the abnormal atrial electrophysiology, would favor production of atrial reentry in chronic lone AF. | 10.1161/01.cir.84.4.1662
| Electrophysiological properties in chronic lone atrial fibrillation. | Circulation |
This study was designed to evaluate the incidence and mechanisms of mitral regurgitation following mitral balloon valvotomy (MBV) in 40 consecutive patients with symptomatic tight pliable mitral stenosis. | 10.1161/01.cir.84.4.1669
| Mitral regurgitation following mitral balloon valvotomy. Differing mechanisms for severe versus mild-to-moderate lesions. | Circulation |
Transthoracic echocardiography with color flow mapping was performed before and 24 hours after the procedure. Patients who developed significant mitral regurgitation following MBV also underwent transesophageal echocardiography. The relation between increased mitral regurgitation and both valvular morphology and proced... | 10.1161/01.cir.84.4.1669
| Mitral regurgitation following mitral balloon valvotomy. Differing mechanisms for severe versus mild-to-moderate lesions. | Circulation |
Baseline clinical, echocardiographic, and procedure-related data for the two groups were similar. Multiple regression analysis did not select any individual valve characteristic (valvular thickening, mobility, calcification, and subvalvular disease), total echocardiographic score, balloon diameter, or ratio of balloon ... | 10.1161/01.cir.84.4.1669
| Mitral regurgitation following mitral balloon valvotomy. Differing mechanisms for severe versus mild-to-moderate lesions. | Circulation |
Thus, severe new mitral regurgitation following MBV is due to noncommissural tearing of the mitral leaflet and confers an adverse long-term prognosis. A mild increase in mitral regurgitation following MBV is frequent and occurs at the site of commissural split or is associated with prolapse of the anterior leaflet. Fur... | 10.1161/01.cir.84.4.1669
| Mitral regurgitation following mitral balloon valvotomy. Differing mechanisms for severe versus mild-to-moderate lesions. | Circulation |
We have previously shown that continuous-wave ultrasound can rapidly dissolve human thrombi in vitro, with 99% of all residual particles measuring less than 10 microns in diameter. To assess the effects of pulsed-wave ultrasound energy on whole blood clots, 1) in vitro studies were preformed to assess precisely the rat... | 10.1161/01.cir.84.4.1680
| Dissolution of peripheral arterial thrombi by ultrasound. | Circulation |
In vitro, we studied 50 samples of human whole blood clots and using an 89-cm-long wire probe, applied pulse-wave energies from 8 to 23 W. The corresponding peak-to-peak tip displacement range was 63.5 - 102 microns. We studied arterial thrombosis in vivo in 21 canine superficial femoral arteries. To produce an acute t... | 10.1161/01.cir.84.4.1680
| Dissolution of peripheral arterial thrombi by ultrasound. | Circulation |
All in vivo canine thromboses were disrupted in 4 minutes or less. All successful recanalizations were confirmed by angiography and in nine cases by angioscopy as well. Angioscopy demonstrated that probe activation caused rapid clot disruption. Histological studies of the vessels showed no evidence of thermal or cavita... | 10.1161/01.cir.84.4.1680
| Dissolution of peripheral arterial thrombi by ultrasound. | Circulation |
Our findings in this experimental canine model suggest that ultrasound clot dissolution has the potential to be an effective and safe alternative to current treatment modalities for peripheral arterial thrombosis. | 10.1161/01.cir.84.4.1680
| Dissolution of peripheral arterial thrombi by ultrasound. | Circulation |
In five chronically instrumented conscious dogs, we studied the effects of rapid pacing on sustained electrically induced atrial fibrillation.
Twenty-three unipolar atrial electrograms were recorded simultaneously from the bundle of Bachmann and the lateral wall of the right and left atria. During sustained a... | 10.1161/01.cir.84.4.1689
| Regional control of atrial fibrillation by rapid pacing in conscious dogs. | Circulation |
These observations show that during electrically induced atrial fibrillation in chronically instrumented conscious dogs, a short excitable gap is present, permitting regional control of the fibrillatory process by rapid pacing. | 10.1161/01.cir.84.4.1689
| Regional control of atrial fibrillation by rapid pacing in conscious dogs. | Circulation |
Maximal ventricular power (PWRmax) reflects contractile state and has the potential to be noninvasively determined. However, its sensitivities to preload, afterload resistance, and inotropic state are incompletely defined. The present study determines these dependencies and proposes a novel power-based contractile inde... | 10.1161/01.cir.84.4.1698
| Evaluation of contractile state by maximal ventricular power divided by the square of end-diastolic volume. | Circulation |
Seven open-chest, autonomically blocked dogs were instrumented with a proximal aortic flow probe, central aortic and ventricular micromanometers, and a conductance catheter for ventricular chamber volume. Preload was transiently reduced by left atrial hemorrhage, and afterload was increased by intra-aortic balloon infl... | 10.1161/01.cir.84.4.1698
| Evaluation of contractile state by maximal ventricular power divided by the square of end-diastolic volume. | Circulation |
31 x Ees - 0.04, r = 0.82, p less than 0.001) and the slope (A) of the dP/dtmax-EDV relation (PWRmax x 1,000/EDV2 = 0.025 x A + 0.02, r = 0.86, p less than 0.001). PWRmax values determined from the product of ventricular pressure and flow versus central aortic pressure and flow were nearly identical over a broad loadin... | 10.1161/01.cir.84.4.1698
| Evaluation of contractile state by maximal ventricular power divided by the square of end-diastolic volume. | Circulation |
PWRmax divided by EDV2 provides a measure of contractile function that is little influenced by loading conditions and has potential for noninvasive clinical use. | 10.1161/01.cir.84.4.1698
| Evaluation of contractile state by maximal ventricular power divided by the square of end-diastolic volume. | Circulation |
Regional sympathetic denervation, such as that produced by a myocardial infarction, causes electrophysiological heterogeneity in the ventricles. The purpose of this study was to test the hypothesis that such denervation could cause drugs to exert heterogeneous myocardial effects. | 10.1161/01.cir.84.4.1709
| Modulation of drug effects by regional sympathetic denervation and supersensitivity. | Circulation |
Sympathetic stimulation increases the amplitude of cesium chloride-induced early afterdepolarizations (EADs). The amplitude of these induced EADs was used to determine whether drug responses were different in innervated versus denervated areas of the heart. A canine model of sympathetic denervation was created at the c... | 10.1161/01.cir.84.4.1709
| Modulation of drug effects by regional sympathetic denervation and supersensitivity. | Circulation |
7% at apex, p less than 0.001). However, during norepinephrine infusion, the EADs recorded from the denervated apex were greater than those recorded from the innervated base (23.3 +/- 7.6% at apex versus 20.6 +/- 6.0% at base, p less than 0.02) due to denervation supersensitivity. | 10.1161/01.cir.84.4.1709
| Modulation of drug effects by regional sympathetic denervation and supersensitivity. | Circulation |
These data show that regional myocardial denervation creates autonomic and electrophysiological heterogeneity and the substrate for heterogeneous drug actions. This drug-induced electrophysiological heterogeneity may be another mechanism for proarrhythmia. | 10.1161/01.cir.84.4.1709
| Modulation of drug effects by regional sympathetic denervation and supersensitivity. | Circulation |
In vitro and in vivo experiments have demonstrated the role of oxidatively modified low density lipoprotein (oxLDL) in eliciting leukocyte/endothelium interaction during early atherogenesis. | 10.1161/01.cir.84.4.1725
| Dietary fish oil reduces leukocyte/endothelium interaction following systemic administration of oxidatively modified low density lipoprotein. | Circulation |
In the present study we investigated the effect of dietary fish oil on oxLDL-induced leukocyte/endothelium interaction using intravital fluorescence microscopy in the dorsal skinfold chamber model in awake Syrian golden hamsters. Hamsters were fed for 4 weeks prior to the experiments with either standard laboratory cho... | 10.1161/01.cir.84.4.1725
| Dietary fish oil reduces leukocyte/endothelium interaction following systemic administration of oxidatively modified low density lipoprotein. | Circulation |
5 microM Cu2+ (6 hours, 37 degrees C). In control hamsters, injection of oxLDL elicited the rolling and sticking of leukocytes to the endothelium of arterioles and postcapillary venules with a maximum 15 minutes after injection (arterioles: from 3 +/- 1 to 91 +/- 25 cells/mm2 at 15 minutes; venules: from 13 +/- 6 to 15... | 10.1161/01.cir.84.4.1725
| Dietary fish oil reduces leukocyte/endothelium interaction following systemic administration of oxidatively modified low density lipoprotein. | Circulation |
The results of the present study suggest that inhibition of leukocyte/endothelium interaction may be one of the mechanisms by which dietary fish oil exerts its protective effects on experimental and clinical atherogenesis. | 10.1161/01.cir.84.4.1725
| Dietary fish oil reduces leukocyte/endothelium interaction following systemic administration of oxidatively modified low density lipoprotein. | Circulation |
Although antithrombotic therapies with aspirin, dipyridamole, and heparin have decreased thrombo-occlusive events, they have not abolished these complications. Endovascular mechanical support, first reported by Dotter in 1969, has been proposed as a means to reduce both acute and chronic vessel closure by providing a s... | 10.1161/01.cir.84.4.1749
| Reduction in thrombus formation by placement of endovascular stents at endarterectomy sites in baboon carotid arteries. | Circulation |
To determine the effects of placing self-expanding stainless steel wire endoprostheses on the accumulation of thrombus at sites of carotid artery endarterectomy we measured platelet deposition continuously for 90 minutes and at 24 and 48 hours by gamma camera imaging of autologous 111In-labeled platelets in six stented... | 10.1161/01.cir.84.4.1749
| Reduction in thrombus formation by placement of endovascular stents at endarterectomy sites in baboon carotid arteries. | Circulation |
80 +/- 0.36 x 10(8) platelets per cm at 30 minutes (p = 0.02), 60 minutes (p = 0.004), and 90 minutes (p = 0.002), respectively. Platelet deposition remained reduced at 24 and 48 hours in stented endarterectomized carotid arteries (ECAs) when assessed as a ratio between net radioactivity in the endarterectomized region... | 10.1161/01.cir.84.4.1749
| Reduction in thrombus formation by placement of endovascular stents at endarterectomy sites in baboon carotid arteries. | Circulation |
We postulate that endovascular stents reduce the thrombogenic effects of flap formation, tearing, dissection, and vasospasm in ECAs. | 10.1161/01.cir.84.4.1749
| Reduction in thrombus formation by placement of endovascular stents at endarterectomy sites in baboon carotid arteries. | Circulation |
There are several clinical situations in which large epicardial coronary arteries are deprived of blood flow, such as occurs when an obstructing thrombus or embolus lodges within a vessel or during coronary dissection. There is little information concerning the effect of flow deprivation on large epicardial coronary ar... | 10.1161/01.cir.84.4.1758
| Influx of neutrophils into the walls of large epicardial coronary arteries in response to ischemia/reperfusion. | Circulation |
We studied a model in which a segment of a large epicardial coronary artery was deprived of blood flow using both proximal and distal clamps for 3 hours followed by reperfusion. On examination by light microscopy of cross sections of the arteries, 19 +/- 6 neutrophils were present in the intima of ischemic/reperfused v... | 10.1161/01.cir.84.4.1758
| Influx of neutrophils into the walls of large epicardial coronary arteries in response to ischemia/reperfusion. | Circulation |
Ultrastructural abnormalities within the myocardium also revealed damage to the microvasculature, including the presence of neutrophils within the vessels and erythrocyte stasis. To rule out the possibility that findings in the large epicardial arteries were due to toxic substances from static blood within the isolated... | 10.1161/01.cir.84.4.1758
| Influx of neutrophils into the walls of large epicardial coronary arteries in response to ischemia/reperfusion. | Circulation |
When large epicardial coronary arteries are deprived of blood flow, followed by reperfusion in this model, neutrophils migrate into the vessel wall as well as into the microvasculature. These abnormalities are associated with reduced endothelial-dependent and endothelial-independent coronary vasodilator reserve. | 10.1161/01.cir.84.4.1758
| Influx of neutrophils into the walls of large epicardial coronary arteries in response to ischemia/reperfusion. | Circulation |
Ultrasonic energy transmitted via flexible wire probes provides a new means of ablating atherosclerotic plaque. We studied the effects of ultrasonic energy (20 kHz) delivered via a ball-tipped wire probe on arterial vasomotor behavior in rabbit thoracic aortas in a perfused whole-vessel model. | 10.1161/01.cir.84.4.1783
| Ultrasonic energy. Effects on vascular function and integrity. | Circulation |
After precontraction with phenylephrine (10(-5) M) or KCl (60 mM), the effects of ultrasonic energy (0.7-5.5 W x 60 seconds, 42-330 J) on arterial vasomotor behavior were measured using long-axis ultrasonic vessel imaging of the proximal (ultrasonic probe-treated) and distal (untreated) control segments. The efficacy o... | 10.1161/01.cir.84.4.1783
| Ultrasonic energy. Effects on vascular function and integrity. | Circulation |
Temperature measurements revealed less than 1 degrees C warming of the vessel wall during as long as 2 minutes of treatment at a power output of 5.5 W. Pathological examination showed no smooth muscle injury at (moderate) power outputs that caused arterial relaxation. At probe-tip power outputs of 2.9-5.5 W, ultrasonic... | 10.1161/01.cir.84.4.1783
| Ultrasonic energy. Effects on vascular function and integrity. | Circulation |
Ultrasonic energy delivered via a flexible-wire probe produces dose-dependent, endothelium-independent smooth muscle relaxation capable of reversing both receptor-mediated and voltage-dependent vasoconstriction in vitro. At moderate power outputs, this relaxation response does not appear to be due to thermal effects or... | 10.1161/01.cir.84.4.1783
| Ultrasonic energy. Effects on vascular function and integrity. | Circulation |
This study tested the hypotheses in the setting of a coronary artery stenosis that 1) planar 99mTc-teboroxime myocardial scans are capable of providing a good estimate of relative coronary flow reserve, and 2) delayed washout of the tracer from the myocardium is a marker of reduced myocardial blood flow and, in certain... | 10.1161/01.cir.84.4.1796
| Comparison of 99mTc-teboroxime with thallium for myocardial imaging in the presence of a coronary artery stenosis. | Circulation |
Experiments were conducted in eight closed-chest domestic swine prepared with an artificial stenosis that reduced diameter of the left anterior descending coronary artery by 80%. Measurements of hemodynamics, regional myocardial blood flow, oxygen, and lactate metabolism were made 1) at baseline, 2) after 5 minutes of ... | 10.1161/01.cir.84.4.1796
| Comparison of 99mTc-teboroxime with thallium for myocardial imaging in the presence of a coronary artery stenosis. | Circulation |
The animal was then killed, and the heart removed for determination of microsphere activity. Under baseline conditions, transmural myocardial blood flow (ml/min/g) distal to the stenosis (1.06 +/- 0.17) was reduced (p less than 0.01) compared with the normally perfused circumflex zone (1.50 +/- 0.31). In response to in... | 10.1161/01.cir.84.4.1796
| Comparison of 99mTc-teboroxime with thallium for myocardial imaging in the presence of a coronary artery stenosis. | Circulation |
17; p less than 0.01). Two hours later flow had returned to baseline levels in both zones, and lactate production during stress (-41.7 +/- 37.5 mumol/min/100 g) had reverted to consumption (13.6 +/- 7.7; p less than 0.05). Analysis of stress teboroxime scans demonstrated 1) an increase (p less than 0.01) in the ischemi... | 10.1161/01.cir.84.4.1796
| Comparison of 99mTc-teboroxime with thallium for myocardial imaging in the presence of a coronary artery stenosis. | Circulation |
74; p less than 0.05; slope = 0.90; intercept = 0); and 3) a close correlation between the IZ:NZ count of the 7-minute scan (0.61 +/- 0.11) and the recovery distal : circumflex flow (0.69 +/- 0.21; r = 0.89; p less than 0.01). The IZ:NZ count also increased (p less than 0.01) between 30-second (0.65 +/- 0.15) and 7-min... | 10.1161/01.cir.84.4.1796
| Comparison of 99mTc-teboroxime with thallium for myocardial imaging in the presence of a coronary artery stenosis. | Circulation |
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