摘要:

Fifteen patients with symptomatic mild-to-moderate and severe chronic aortic regurgitation (AR) performed supine bicycle exercise while measurements of rest and exercise hemodynamics and left ventricular function were obtained. A continuous Doppler method was used to determine the change in distribution of total left ventricular stroke volume between forward stroke volume and regurgitant volume (RgV) with exercise. The pulmonary arterial wedge pressure (PAWP) was lower in the mild-to-moderate AR group than in the severe AR group at rest (8 + 1.2 vs 19 + 3.6 mm Hg, p = 0.01) and during exercise (15 + 3.9 vs 30 + 4.3 mm Hg, p = .02). In all patients there were increases in heart rate (78 ± 4 to 96 + 5 beats/min, p < .001), forward stroke volume (41 + 2 to 46 + 2 mI/m2), and the cardiac index (3.1 -+ 0.2 to 4.4 0.3 liters/min-M2, p < .001), despite a fall in total left ventricular stroke volume index from 84 5 to 76 + 5 ml/m2 (p = .03). The systemic vascular resistance (SVR) decreased with exercise from 1277 + 72 to 1031 64 dynes-sec/cm5 (p < .001), and the RgV and regurgitant fraction (RgF) both decreased with exercise from 43 + 5 ml/m2 to 30 ± 4 ml/m2 (p = .002) and 0.50 -+- 0.03 to 0.37 ± 0.03 (p < .001), respectively. Left ventricular ejection fraction increased on exercise from 0.51 + 0.03 to 0.55 + 0.03 (p = .02) for the group, but it either decreased or failed to increase by at least 0.05 in seven of 13 patients. The change in ejection fraction on exercise was directly related to the change in SVR (r = .80, p < .001). We conclude that: (1) in patients with mild-to-moderate AR, the PAWP is generally normal at rest and exercise, (2) in most of those with severe AR, the PAWP is elevated at rest and increases significantly with exercise, which is the likely mechanism for dyspnea on exertion in these patients, (3) the cardiac index in both groups is normal at rest and increases on exercise, (4) the increase in cardiac output results from both an increased heart rate and forward stroke volume, (5) the increase in forward stroke volume results from reductions of RgV and RgF, (6) the RgV and RgF are decreased due to a decreased SVR, and (7) the ejection fraction response to exercise is variable and correlates best with changes in SVR with exercise.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Fifteen patients with symptomatic mild-to-moderate and severe chronic aortic regurgitation (AR) performed supine bicycle exercise while measurements of rest and exercise hemodynamics and left ventricular function were obtained. A continuous Doppler method was used to determine the change in distribution of total left ventricular stroke volume between forward stroke volume and regurgitant volume (RgV) with exercise. The pulmonary arterial wedge pressure (PAWP) was lower in the mild-to-moderate AR group than in the severe AR group at rest (8 + 1.2 vs 19 + 3.6 mm Hg, p = 0.01) and during exercise (15 + 3.9 vs 30 + 4.3 mm Hg, p = .02). In all patients there were increases in heart rate (78 ± 4 to 96 + 5 beats/min, p < .001), forward stroke volume (41 + 2 to 46 + 2 mI/m2), and the cardiac index (3.1 -+ 0.2 to 4.4 0.3 liters/min-M2, p < .001), despite a fall in total left ventricular stroke volume index from 84 5 to 76 + 5 ml/m2 (p = .03). The systemic vascular resistance (SVR) decreased with exercise from 1277 + 72 to 1031 64 dynes-sec/cm5 (p < .001), and the RgV and regurgitant fraction (RgF) both decreased with exercise from 43 + 5 ml/m2 to 30 ± 4 ml/m2 (p = .002) and 0.50 -+- 0.03 to 0.37 ± 0.03 (p < .001), respectively. Left ventricular ejection fraction increased on exercise from 0.51 + 0.03 to 0.55 + 0.03 (p = .02) for the group, but it either decreased or failed to increase by at least 0.05 in seven of 13 patients. The change in ejection fraction on exercise was directly related to the change in SVR (r = .80, p < .001). We conclude that: (1) in patients with mild-to-moderate AR, the PAWP is generally normal at rest and exercise, (2) in most of those with severe AR, the PAWP is elevated at rest and increases significantly with exercise, which is the likely mechanism for dyspnea on exertion in these patients, (3) the cardiac index in both groups is normal at rest and increases on exercise, (4) the increase in cardiac output results from both an increased heart rate and forward stroke volume, (5) the increase in forward stroke volume results from reductions of RgV and RgF, (6) the RgV and RgF are decreased due to a decreased SVR, and (7) the ejection fraction response to exercise is variable and correlates best with changes in SVR with exercise.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

To evaluate rhythm and QRS-T changes after cardioversion of induced ventricular arrhythmias, 56 patients underwent continuous three-lead and serial 12-lead electrocardiographic monitoring for 15 min after 77 cardioversions. Fifty patients were cardioverted externally and nine internally with an implanted automatic cardioverter/defibrillator. Initial energy for external cardioversion was 200 Wsec in 57 of 64 arrhythmia episodes. Two hundred watt-seconds of energy effectively terminated 41 of 44 episodes of ventricular tachycardia and six of 13 episodes of ventricular fibrillation (p < .001). Early bradycardia (mean cycle length 1200 msec during the first 5 sec) occurred after 17 of 64 external and two of 13 internal cardioversions (p = NS) in a total of 16 patients. Bradycardia persisted at 10 sec after cardioversion in nine patients. Early bradycardia was associated with the need for multiple cardioversions to terminate the arrhythmia (six of 10 multiple cardioversions vs 13 of 67 single cardioversions, p < .05) and the presence of inferior myocardial infarction (eight of 16 patients with vs eight of 40 patients without inferior infarction, p < .05). Supraventricular tachycardia (cycle length <500 msec) occurred after 19 of 64 external and six of 13 internal cardioversions (p = NS). Nonsustained ventricular tachycardia (4 to 40 beats) was observed after seven external cardioversions, with three episodes lasting 3 sec or more. Excluding patients with bundle branch block, ST segment elevation ('- 1 mm) occurred after 11 of 58 external cardioversions and after one of 12 internal cardioversions (p = NS) and ST segment depression (−1 mm) was noted after 25 of 58 external and three of 12 internal cardioversions (p = NS). All but one ST segment change resolved by 15 min. Thus, after cardioversion of induced ventricular arrhythmias (1) over 25% of patients develop marked bradycardia and/or supraventricular tachycardia with the development of bradycardia related to the need for multiple cardioversions for arrhythmia termination and previous inferior infarction, (2) ST segment changes are common but short-lived, and (3) the frequency of arrhythmias and ST changes is comparable after external and internal cardioversion. These observations may have implications for backup pacing and triggering rates for automatic cardioverting/defibrillating devices and for the diagnosis of ischemia after termination of induced ventricular arrhythmia.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

We used combined two-dimensional and pulsed Doppler echocardiography to examine 37 infants and children with coarctation of the aorta and 19 normal subjects. The ages ranged from 1 day to 16 years. We compared the differences between the Doppler flow signal from the ascending aorta and the descending aorta below the coarctation in each patient, as well as the differences between the corresponding flow signals in the aorta of patients with coarctation and normal subjects. Six variables were measured from each Doppler signal: acceleration slope (peak rate of acceleration), acceleration time (time from onset of flow to the peak systolic frequency), antegrade flow time, peak systolic frequency, peak velocity of flow, and deceleration slope (peak rate of deceleration). In patients with coarctation, each of these variables was significantly different in the descending aorta compared with the ascending aorta. There was a decrease in the acceleration slope (14 ± 13 vs 87 ± 67 kHz/sec) (mean ± SD), peak systolic frequency (1.8 ± 1.0 vs 5.2 ± 1.9 kHz), peak velocity of flow (0.70 + 0.40 vs 1.4 ± 0.44 m/sec), and deceleration slope (11 ± 11 vs 27 ± 12 kHz/sec). There was also a prolongation of the acceleration time (140 ± 50 vs 88 22 msec) and antegrade flow time (330 + 120 vs 270 ± 50 msec). In addition, these variables in the descending aorta of patients with coarctation were significantly different from those in the descending aorta of normal subjects. In eight patients with coarctation and a patent ductus arteriosus, there was no difference in the antegrade flow time between the descending and ascending aorta (240 + 64 vs 230 + 20 msec), whereas this was significantly prolonged in the descending aorta compared with the ascending aorta in patients with coarctation and no patent ductus arteriosus (350 + 120 vs 280 ± 52 msec). Pulsed Doppler ultrasound is a useful modality for evaluating patients with suspected coarctation of the aorta. In the presence of a patent ductus arteriosus with coarctation, the antegrade flow time is not prolonged but the other indexes remain abnormal. This may provide a means of assessing response to administration of prostaglandin in critically ill newborns with coarctation.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

To evaluate the detectability of cardiac septal defects by electrocardiographically synchronized (ECG-gated) magnetic resonance imaging (MRI), 48 subjects were imaged, including 18 normal and 30 abnormal subjects in whom 22 ventricular septal defects (VSDs) and nine atrial septal defects (ASDs) had been diagnosed angiographically. Two radiologists with ECG-gated cardiac MRI experience read the scans in a blinded fashion, and the results were evaluated by receiver operator characteristic curve analysis. The detectability of VSDs appeared greater than that of ASDs, although statistical significance at the .05 level was not achieved. The reported sensitivity and specificity of echocardiography in the detection of VSDs is comparable to MRI, whereas echocardiography probably is superior to MRI for detection of ASDs. Although MRI is potentially valuable in the diagnosis of various complex congenital cardiac defects, echocardiography is probably superior in the detection of VSDs and ASDs.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

We analyzed blood flow pattern in the interatrial communication in 24 patients with complete transposition of the great arteries (TGA). Eight had TGA with atrial shunt (group 1), nine had TGA with patent ductus arteriosus or ventricular septal defect (group 2), and seven had pulmonary arterial banding and Blalock-Taussig shunt (group 3). The flow pattern was determined at the site of atrial septal defect by Doppler echo beam directed as perpendicular to the septum as possible. The flow pattern was composed of a left-to-right (L-R) flow and right-to-left (R-L) flow. The turning point (T1) from the R-L to L-R flow occurred immediately after the initiation of the QRS on the electrocardiogram and was common in all groups. The other turning point (T2) from L-R to R-L occurred after the second heart sound (S2). The S2-T2 interval decreased on inspiration, indicating prolongation of the period of R-L flow. The minimum S2-T2 interval ranged from 20 to 70 (mean + SD 50 + 18) msec in group 1, from 70 to 130 (114 ±- 25) msec in group 2, and from 50 to 138 (75 29) msec in group 3. The maximum S2-T2 interval ranged from 48 to 110 (88 21) msec in group 1, from 140 to 235 (175 36) msec in group 2, and from 80 to 170 (111 30) msec in group 3. The minimum ratio of L-R flow duration to that in the whole cardiac cycle (TI-T2/RR) was 0.47 to 0.61 (mean ± SD 0.53 + 0.04) in group 1, 0.66 to 0.88 (0.74 + 0.10) in group 2, and 0.53 to 0.77 (0.65 0.08) in group 3. The maximum TI-T2/RR ratio ranged from 0.57 to 0.74 (0.67 + 0.06) in group 1, from 0.75 to 1.0 (0.87 + 0.09) in group 2, and from 0.68 to 0.91 (0.79 0.08) in group 3. We conclude that, in patients with TGA (1) an interatrial shunt occurs in a rather simple flow pattern, with L-R shunting mainly in systole and R-L shunting mainly in diastole, (2) the pattern is affected by respiration, and (3) the associated ventricular septal defect or patent ductus arteriosus causes the shunt, which directs flow toward the pulmonary artery and away from the systemic ventricle or artery.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

This study was undertaken to compare the accuracies of the two-dimensional echocardiographic (2DE) and Doppler pressure half-time methods for the noninvasive estimation of cardiac catheterization measurements of mitral valve area in patients with pure mitral stenosis both with and without a previous commissurotomy. Data were retrospectively obtained from 74 consecutive patients who underwent cardiac catheterization within a 30 month period for evaluation of mitral stenosis, and who had two-dimensional echocardiograms performed before catheterization. Six patients (8.1%) had technically inadequate 2DE images and their data were excluded from analysis. Two of these patients had undergone commissurotomy, while the remaining four had not. Continuous-wave Doppler echocardiographic examinations were attempted in 45 patients and adequate measurements of pressure halftimes were obtained in all patients studied. Mitral valve area by two-dimensional echocardiography was measured as the planimetered area along the inner border of the smallest mitral orifice visualized during short-axis scanning, while pessure half-time was calculated as the interval between the peak transmitral velocity and velocity/V2 as measured from the envelope of the Doppler spectral signal. Calculations from catheterization represented the minimal valve area at rest as derived from the Gorlin formula with the use of pressure gradients and thermodilution measurements of cardiac output. Thirtyseven of the patients had had a previous mitral commissurotomy a mean of 11.2 ± 5.4 years before, while the remaining 37 patients were previously unoperated. Mean valve area as determined at catheterization for the total group of patients ranged from 0.37 to 2.30 cm2 (mean = 1.08 ± 0.42 cm2). Linear regression analysis of data from the group of 33 previously unoperated patients revealed a good correlation between 2DE and catheterization measurements of mitral valve area (r = .83, y = 0.79x + 0.29, SEE = 0.26 cm2). Similarly, the correlation between Doppler measurements of mitral valve area were also good (r = .85, y = 0.84x + 0.17, SEE = 0.22 cm2). However, in the group of 35 patients who had undergone commissurotomy, the Doppler pressure half-time correlated much better with catheterization measurements (r = .90, y = 0.63x + 0.39, SEE = 0.14 cm2) than with 2DE estimates (r = .5 8, y = 0.47x + 0. 6 1, SEE = 0. 28 cm2) Reproducibility was similar for the two noninvasive methods, with a mean error of 0.14 cm2 for 2DE planimetry, and of 0.15 cm2 for Doppler pressure half-time. Thus, our data show that both 2DE and Doppler pressure half-time methods provide accurate noninvasive estimates of mitral orifice area in patients who have not undergone surgery. However, the Doppler pressure half-time is superior to two-dimensional echocardiography in estimating mitral valve area in patients who have undergone commissurotomy.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

The immediate effects of intravenous diltiazem effects and short-term (4 weeks) of the oral drug on systemic and regional hemodynamics, cardiac structure, and humoral responses were evaluated by previously reported methods in nine patients with mild-to-moderate essential hypertension and in one patient with primary aldosteronism. Diltiazem was first administered in three intravenous doses of 0.06, 0.06, and 0.12 mg/kg, respectively; patients were then treated for 4 weeks with daily doses ranging from 240 to 360 mg (average 300 mg). Intravenous diltiazem immediately reduced mean arterial pressure (from 115 ± 3 to 96 ± 3 mm Hg; p < .01) through a fall in total peripheral resistance index (from 37 ± 3 to 23 ± 2 U/M2; p < .01) that was associated with an increase in heart rate (from 66 ± 2 to 77 ± 3 beats/min; p < .01) and cardiac index (from 3.3 ± 0.3 to 4.3 ± 0.4 liters/min/m2; p < .01). These changes were not associated with changes in plasma levels of catecholamines or aldosterone or in plasma renin activity. After 4 weeks the significant decrease in mean arterial pressure persisted (104 ± 3 mm Hg; p < .01) and there were still no changes in the humoral substances or plasma volume. Renal blood flow index increased (from 368 + 52 to 462 + 57 ml/min/m2; p < .01) and renal vascular resistance index decreased (from 0.37 + 0.06 to 0.26 + 0.04 U/M2; p < .01), while splanchnic hemodynamics did not change. Left ventricular mass significantly decreased (from 242 ± 16 to 217 ± 14 g; p < .01). Thus, the fall in arterial pressure produced by diltiazem was associated with improved renal hemodynamics and reduced left ventricular mass without expansion of intravascular volume or alterations in circulating humoral substances.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

The relationship between diuretic therapy and possible increased risk of coronary heart disease (CHD), especially sudden death, is controversial. The initial report from the Multiple Risk Factor Intervention Trial (MRFIT) raised the possibility that the increased CHD mortality observed in a subset of special intervention men with hypertension and certain electrocardiographic abnormalities on their baseline examination might be an unexpected adverse effect of diuretic therapy. Subsequent reports from the MRFIT have revealed a stronger association of CHD mortality to hydrochlorothiazide than to chlorthalidone. There was no consistent relationship of CHD mortality to the dose of either drug, to the most recent serum potassium level, or to the presence of ventricular premature beats. Unfavorable trends of the same magnitude were also seen among similar white men in the Hypertension Detection and Follow-up Program and in the Oslo hypertension trial, although the sample sizes in these two studies were too small to yield clearcut conclusions. Clinical studies have shown an increased risk of CHD death among hypertensive men with left ventricular hypertrophy. Such men are also noted to have a higher frequency of ventricular premature beats, even in the absence of diuretic therapy. Other studies have shown that diuretic-induced hypokalemia is accentuated in the presence of epinephrine and that low potassium levels decrease the threshold for ventricular fibrillation. Thus, although the evidence is still incomplete, it is possible that the excess CHD mortality among MRFIT special intervention men with electrocardiographic abnormalities may have been caused by a combination of increased left ventricular mass in the presence of coronary atherosclerosis, and hypokalemia caused by good compliance with diuretic therapy and accentuated by stress-induced increases in circulating catecholamines. Given the very large population of patients receiving diuretic therapy, further evaluation of this possibility is important.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

We developed an isolated limb preparation to evaluate the direct vasoactive properties of cardioactive drugs on the forearm vasculature in patients with congestive heart failure. Using this model, we infused milrinone in subsystemic doses (1, 10, and 20 μg/min per 100 ml forearm volume [FAV]) into the brachial artery of 13 patients with moderate-to-severe congestive heart failure. We monitored forearm hemodynamics, systemic hemodynamics, and milrinone plasma concentration from both the forearm venous effluent and pulmonary artery. This preparation enabled us to assess the direct forearm vascular response to milrinone. Compared with baseline forearm blood flow (2.46 – 1.37 ml/min/100 ml FAV), the three doses of milrinone resulted in increases in forearm blood flow to 2.66 ± 1.43, 4.21 ± 1.79, and 6.73 ± 3.69 ml/min/100 ml FAV. This was associated with a reduction of forearm vascular resistance from the baseline value of 52 + 38 U to 47 ± 36, 25 + 13, and 17 ± 10 U. The p value for the difference in response of flow and resistance after the 10 and 20 gg doses vs that at baseline was .05. This forearm vasodilatation occurred without change in systemic hemodynamics or therapeutic milrinone plasma concentrations in the pulmonary artery. In five patients, we compared the response to intra-arterial milrinone with that of nitroprusside. At a dose of 10 μg/min/ 100 ml FAV, the response to nitroprusside (7.20 ± 3.24 ml/min/100 ml FAV) was greater than that to milrinone (4.65 2.18 ml/min/100 ml FAV) (p < .05). When milrinone was administered by a systemic intravenous route, the magnitude of forearm vasodilatation was not as great as that with intra-arterial milrinone, suggesting different sensitivities of vasodilatation in alternate vascular beds or the influence of baroreceptor autoregulation. Thus, this study identifies direct vasodilator properties of milrinone that are independent of its inotropic activity.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID