Effects of atenolol on exercise capacity in patients with mitral stenosis with sinus rhythm

Exercise capacity is frequently impaired in patients with mitral stenosis (MS) and sinus rhythm (SR). The resulting increased heart rate, which shortens the diastolic filling period, and the increased cardiac output lead to further elevations of left atrial pressure and subsequent pulmonary congestion. The effect of the beta-receptor blocking agent atenolol, 100 mg/day, was assessed in 13 patients with MS and SR. Exercise performance was assessed using a modified multistage Bruce protocol after 2 weeks of placebo and after 2 weeks therapy with atenolol in a single-blind, crossover, placebo-controlled, randomized study. Atenolol resulted in significant decreases in mean heart rates at rest and during exercise (p = 0.0015) and a significant increase in total exercise time (p = 0.0015). Maximal exercise capacity was also significantly improved (p = 0.0015). All patients were both objectively and subjectively improved by atenolol. Thus, beta-blockade with atenolol improves exercise capacity in patients with MS and SR and may be of benefit to most such patients. The improved effort tolerance is attributed to reduction of the exercise-associated sinus tachycardia by beta-blockade, allowing a longer diastolic filling period and better left atrial decompression.     

Effect of ivabradine vs atenolol on heart rate and effort tolerance in patients with mild to moderate mitral stenosis and normal sinus rhythm

BackgroundPatients with mitral stenosis become symptomatic at a higher heart rate. We studied the comparative efficacy of heart rate control with ivabradine or atenolol and its effect on effort tolerance in patients with mild-moderate mitral stenosis in normal sinus rhythm.Methods and ResultsFifty patients with mild-moderate mitral stenosis in sinus rhythm were randomized to receive ivabradine or atenolol for 4 weeks each in an open-label, randomized, crossover design trial. A 24-hour Holter and treadmill test was performed at baseline and after each active treatment period. In the first treatment period, 23 patients were allocated to ivabradine (22 analyzed), and 27 were allocated to atenolol (26 analyzed). In the second period, all 48 patients were analyzed. Ivabradine increased the mean total exercise time to 500.7 seconds (SD 99.7) from a baseline of 410.3 seconds (SD 115.4), and atenolol increased it to 463.7 seconds (SD 113.1). The point estimate (absolute difference between ivabradine and atenolol) was 35.27 seconds (95% CI 15.24–55.20; P = .0009). The point estimate for decrease in the maximum exercise heart rate and mean heart rate were 7.64/min (95% CI 0.37–15.9; P = .04) and 5.61/min (95% CI 2.51–8.71; P = .0007), respectively.ConclusionsIvabradine is more effective than atenolol for effort related symptoms in patients with mild-moderate mitral stenosis and normal sinus rhythm.     

Short-term course under beta blockers of clinical and echocardiographic parameters in mitral stenosis in sinus rhythm

The purpose of this study is to evaluate the short-term benefit of a beta-blocker (atenolol) on clinical and echocardiographic parameters of patients presenting isolated or predominant mitral stenosis in sinus rhythm. It is a prospective study performed on 26 patients who have had a clinical and echocardiographic assessment before and 15 days after treatment by atenolol. After 15 days of beta-blocker treatment, there is a significant improvement of dyspnea (57.6% in class III or IV before beta-blockade versus 15.3% with atenolol; P = 0.001) and a significant decrease of the heart rate (83.3 +/- 15.2 versus 68.9 +/- 13.9; P = 0.001) and the diastolic blood pressure (8 mmHg +/- 1.3 versus 7.2 mmHg +/- 0.9; P = 0.01). The Doppler echocardiography shows a significant increase of the stroke volume calculated by the Doppler method (28.7 +/- 6.2 versus 38.6 +/- 9.7 mL; P = 0.04). There is an insignificant trend to an improvement of the left ventricular systolic function, an increase of cardiac output and the decrease of the mean transmitral gradient. The factors associated with the failure of beta-blocker treatment are: the right heart failure (P = 0.04) and the low diastolic blood pressure (P = 0.01). The beta-blockers could be a logical and effective treatment of patients with mitral stenosis waiting for balloon commissurotomy or surgery.     

Hemodynamic response to exercise after propranolol in patients with mitral stenosis.

Hemodynamic response to exercise before and 10 minutes after propranolol (5 mg intravenously) was studied in 10 young patients with pure mitral stenosis who had normal sinus rhythm and no cardiac failure. After propranolol the mean heart rate and cardiac index at rest were lower than during the control state (respectively, 95 +/- 4 versus 82 +/- 3 beats/min, P less than 0.005; 3.4 +/- 0.2 versus 2.8 +/- 0.1 liters/min per m2, P less than 0.025). As a result, the mean pulmonary wedge pressure and mean mitral valve gradient at rest were lower (respectively, 22 +/- 2 versus 18 +/- 2 mm Hg, P less than 0.005; 24 +/- 2 versus 17 +/- 2 mm Hg, P less than 0.001). During exercise after propranolol the values of pulmonary wedge pressure and mitral valve gradient were lower than control values during exercise (respectively, 39 +/- 3 versus 30 +/- 2 mm Hg, P less than 0.005; 44 +/- 3 versus 32 +/- 3 mm Hg, P less than 0.005), again because of the lower heart rate and cardiac index (130 +/- 6 versus 104 +/- 6 beats/min, P less than 0.001; 4.6 +/- 3 versus 3.7 +/- 2 liters/min per m2, P less than 0.01). Left ventricular end-diastolic pressure and stroke index showed no significant changes. Thus, propranolol may benefit patients with pure mitral stenosis with sinus rhythm and no cardiac failure whose symptoms occur during those reversible conditions characterized by an increase in heart rate or cardiac output, or both.     

Failure of oral atenolol and verapamil to increase the capacity and duration of exercise in patients in sinus rhythm with mitral stenosis

The efficacy of oral atenolol in increasing the capacity and duration of exercise in 43 patients in sinus rhythm with mitral stenosis was evaluated and compared with that of oral verapamil in an open-label cross-over design. It was observed that although oral atenolol (100 mg per day) caused significant reductions in heart rate while resting and during exercise (P less than 0.001), the increases in capacity and duration of exercise were not significant. Oral verapamil (80 mg three times per day) also caused significant reductions in the heart rates at rest and during exercise (P less than 0.05) but the increases observed, although greater than that with atenolol, failed to reach the level of statistical significance. Occasional side effects occurred with both the drugs. Subjective symptoms of dyspnoea at rest and on exertion were relieved with both the drugs. We conclude that, although both drugs reduce the symptoms of dyspnoea, they cause only minor increases in the objective parameters. They do not, therefore, provide an alternative to surgery and have only a temporary place in the management of patients in sinus rhythm with mitral stenosis who are awaiting surgery.     

Serum N-terminal pro-BNP levels correlate with symptoms and echocardiographic findings in patients with mitral stenosis

This study is designed to evaluate the N-terminal pro-BNP (NTproBNP) levels in patients with mitral stenosis (MS) and its possible correlation with clinical and echocardiographic parameters of the disease. The study group consisted of 29 patients with isolated MS (patients with greater mild regurgitation were excluded) and 20 normal control subjects of similar age and gender distribution. Blood samples for NTproBNP were collected at the time of clinical and echocardiographic examination. NTproBNP levels were elevated in patients with MS compared to controls (325 +/- 249 pg/dL [19.9-890] versus 43 +/- 36 pg/dL [5.76-193.3], P < 0.001). Patients with atrial fibrillation had significantly higher NTproBNP levels compared to those with sinus rhythm (561 +/- 281 pg/dL versus 254 +/- 194 pg/dL, P = 0.044). MS patients with sinus rhythm also had higher NTproBNP levels compared to controls (254 +/- 194 pg/dL versus 43 +/- 36 pg/dL, P = 0.00011). NT pro BNP levels correlated to the LA (R = 0.73, P < 0.0001) and RV (R = 0.41, P = 0.042) diameters, mitral valve area (R =-0.45, P = 0.025), mean mitral gradient (R = 0.57, P = 0.003), peak PAP (R = 0.7, P = 0.03), and NYHA functional class (R = 0.61, P = 0.007). In conclusion, serum NTproBNP levels correlate well with echocardiographic findings and functional class in patients with MS and can be used as a marker of disease severity. Additionally, it may have a potential use as an additional noninvasive and relatively cheap method in monitoring disease progression especially in patients with poor echocardiographic windows.     

Effect of maintenance digoxin therapy on aerobic performance and exercise left ventricular function in mild to moderate heart failure due to coronary artery disease: a randomized, placebo-controlled, crossover trial

Despite 200 years of use, the ability of digitalis glycosides to improve exercise capacity in patients with congestive heart failure remains controversial, partly because of imprecise end points and suboptimal study design. Therefore, this question was examined in 10 ambulatory patients (8 men and 2 women) aged 46 to 70 years (mean 57.8) in sinus rhythm with mild to moderate chronic stable congestive heart failure due to coronary artery disease and systolic left ventricular dysfunction (ejection fraction 32 +/- 12). All underwent maximal treadmill exercise with respiratory gas analysis and upright cycle ergometry with gated radionuclide angiography after 4 weeks of digoxin or placebo therapy, administered in a randomized double-blind crossover protocol. Neither treadmill exercise duration (7.7 +/- 2.3 versus 7.3 +/- 2.7 min) nor peak oxygen consumption (18.7 +/- 3.7 versus 18.4 +/- 5.4 ml/kg per min) differed between digoxin and placebo regimens. However, the change in peak oxygen consumption induced by digoxin was inversely related to the peak oxygen consumption during placebo therapy (r = -0.64, p less than 0.05). At maximal treadmill effort, heart rate (138 +/- 16 versus 141 +/- 21 beats/min), oxygen pulse (10.3 +/- 2.1 versus 9.9 +/- 2.2 ml/beat), ventilation (40.3 +/- 10.6 versus 42.0 +/- 10.8 liters/min) and ventilatory equivalent (29.4 +/- 4.8 versus 31.5 +/- 6.8) did not differ between digoxin and placebo treatment, although systolic blood pressure was higher during digoxin therapy (163.0 +/- 23.1 versus 153.2 +/- 25.3 mm Hg, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Impact of atrial fibrillation on clinical status, atrial size and hemodynamics in patients after mitral valve replacement.

BACKGROUND AND AIM OF THE STUDY: The association between mitral valve disease and atrial fibrillation (AF) is well known, but few data exist regarding the impact of AF after mitral valve replacement (MVR) on NYHA functional class, atrial size and hemodynamic parameters. The present study was conducted to evaluate these issues. METHODS: Eighty-six patients (26 men, 60 women) who underwent MVR were evaluated by transthoracic echocardiography. Fifty-nine patients had chronic AF (AF group), and 27 were in sinus rhythm (sinus group). Variables analyzed included end-systolic left atrial and right atrial areas, tricuspid regurgitation, and presence and duration of AF. Peak and mean transprosthetic mitral valve gradients and pulmonary pressure were estimated by Doppler echocardiography. RESULTS: Groups were matched for age, sex and time from MVR (mean 6.6 years). Sixty-four patients (77%) had rheumatic heart disease, 18 (21%) had mitral valve disease, and two (2%) had mitral valve prolapse. Mean duration of AF was 11+/-12 years (range: 8-50 years). Preoperatively, AF patients had a worse NYHA class than sinus patients (2.8+/-0.8 versus 1.1+/-0.7, p = 0.001), but both had similar fractional shortening of the left ventricle and preserved prosthetic mitral valve function. Multivariate analysis identified AF as a single predictor of NYHA class after MVR. Although left and right atrial areas were larger in AF patients (47+/-25 versus 27+/-7 cm2, p = 0.0001 and 30+/-12 versus 17+/-5 cm2, p = 0.0001, respectively), the left:right atrial size ratio was not significantly different between groups. Multivariate analysis identified mean transmitral gradient and duration of AF as independent predictors of left atrial size after MVR (p = 0.01 and p = 0.0001, respectively). Tricuspid regurgitation and duration of AF were independent predictors of right atrial size (p = 0.003 and p = 0.0001, respectively). CONCLUSION: The presence of AF after MVR is associated with a worse NYHA functional class, increased transmitral gradients, and larger areas of both atria, when compared with sinus rhythm. Hence, a special effort should be made to correct arrhythmia during surgery, and in case of paroxysmal arrhythmia, earlier surgery should be considered before the condition becomes chronic.     

Hemodynamic effects and long-term outcome of percutaneous balloon valvuloplasty in patients with mitral stenosis and atrial fibrillation

BACKGROUND: The presence of atrial fibrillation (AF) has been identified as a predictor of a suboptimal result in some patients undergoing percutaneous balloon valvuloplasty in the treatment of symptomatic rheumatic mitral stenosis. HYPOTHESIS: Atrial fibrillation adversely affects the short- and long-term outcome of patients with mitral stenosis undergoing percutaneous balloon valvuloplasty. METHODS: A retrospective chart review of 104 consecutive patients with rheumatic mitral stenosis undergoing percutaneous balloon valvuloplasty was performed. A successful procedure was defined as a final mitral valve area > or = 1.5 cm2 and the absence of a complication. Endpoints included freedom from mitral valve replacement, death, and repeat balloon valvuloplasty at 5 years. RESULTS: A successful procedure was obtained in 89% of patients with sinus rhythm and in 78% of patients with AF (p = NS). Patients in sinus rhythm had a greater cardiac output resulting in a larger final valve area than patients in AF (1.8 vs. 1.6 cm2, p < 0.05). Freedom from valve replacement, death, and repeat balloon valvuloplasty at 5 years was 75% for patients in AF and 76% for patients in sinus rhythm (p = NS). Lower postprocedure mitral regurgitation grade and absence of prior commissurotomy were the only independent predictors of event-free survival. CONCLUSIONS: Patients with mitral stenosis and AF have lower cardiac outputs and gradients than patients with sinus rhythm, despite similar valve areas. The long-term outcome of balloon valvuloplasty is independent of the initial cardiac rhythm.     

Failure of propranolol to improve exercise tolerance in patients with mitral stenosis in sinus rhythm.

Propranolol reduces left atrial pressure at rest and during exercise in patients with mitral stenosis by lowering cardiac output and heart rate. Ten patients (aged 19-56) with moderate to severe isolated mitral stenosis were studied to determine whether propranolol increased their exercise tolerance. All were in sinus rhythm and free of left or right ventricular failure. Patients were trained in an individually graded bicycle or treadmill exercise protocol that provoked a reproducible degree of near maximal dyspnoea during the second three minute stage of exercise. Propranolol (80 mg or 120 mg) or matching placebo in two or three divided daily doses was given for one week in random double blind fashion. Exercise testing and questioning about subjective clinical response were carried out at the end of each week by an investigator who was unaware of the patient's heart rate. During propranolol treatment the heart rate was 19 beats/minute slower at rest and 38 beats/minute slower at peak exercise, but there was no change in mean exercise time to dyspnoea (274 s during propranolol vs 283 s during placebo). Four patients felt worse during the propranolol week, one patient felt better during the propranolol week, and five patients felt no difference between the two weeks. Propranolol did not improve objective or subjective exercise tolerance in patients with isolated mitral stenosis in sinus rhythm.     

Features of patients with severe mitral stenosis with respect to atrial rhythm. Atrial fibrillation in predominant and tight mitral stenosis.

The aim of this study was to assess the features of patients with severe mitral stenosis in relation to atrial rhythm. Six hundred and fifty patients (pts) with severe mitral stenosis (MS) (valve area less than or equal to 1.5 cm2) who underwent percutaneous balloon commissurotomy (n = 600) or surgery (n = 50) were classified into 3 groups according to their atrial rhythm (AR): group A: sinus rhythm (SR) (n = 379), group B: SR with episodes of transient atrial fibrillation (AF) (n = 65), group C: permanent AF (n = 206). Uni- and multivariate analysis of clinical, echocardiographic and hemodynamic parameters with respect to the atrial rhythm was performed. Some parameters were comparable in all 3 groups: sex, pulmonary, right and left atrial pressures, mitral valve area, incidence of associated aortic valve disease. Nine parameters were different: mean age, NYHA class III or IV, previous commissurotomy, previous embolism, cardiac index, mitral regurgitation, tricuspid regurgitation, left atrium diameter, mitral calcification. Multivariate analysis, identified age, left atrial diameter and presence of mitral calcification as independent predictors of atrial fibrillation. Transoesophageal echocardiography was performed in 167 cases. A spontaneous echo contrast was recorded in 106 cases (63.5%) and was significantly correlated with a history of embolism and or left atrial thrombi detected by echocardiography. Atrial fibrillation, size of left atrium, severity of mitral stenosis and cardiac index were found to be independent predictive factors of spontaneous echo contrast.     

Beta-blocker therapy for dynamic left-ventricular outflow tract obstruction

BACKGROUND: In a small but significant group of elderly patients who present with breathlessness, dynamic left-ventricular outflow tract obstruction (DLVOTO) may be responsible for symptom generation. The aim of our study was to investigate the effect of beta-blockade on ventricular physiology and symptoms in patients with DLVOTO. METHODS: We performed a pilot study in 15 patients (age 76+/-10 years, mean+/-S.D., 14 female) with symptoms of exercise intolerance (New York Heart Association, NYHA, class 2.7+/-0.5). All patients had normal resting left ventricular (LV) systolic function together with DLVOTO based on the presence of basal septal hypertrophy and the development of high outflow tract velocities on stress echocardiography. All were commenced on oral atenolol (mean dose 45+/-19 mg), but this could not be tolerated in four patients due to a deterioration in clinical status. RESULTS: In the remaining 11 patients who could tolerate atenolol therapy, the rate pressure product was significantly lower (23%, P=0.028) and there was a marked reduction in LV outflow tract velocity (23%, P=0.001) following beta-blockade. Patient symptoms improved significantly following atenolol therapy, with a reduction in mean NYHA class from 2.8+/-0.4 to 1.5+/-0.5 (P<0.0001). CONCLUSIONS: Beta-blockade may represent a beneficial therapeutic approach in selected patients with DLVOTO as identified by stress echocardiography.     

Failure of propranolol to improve exercise tolerance in patients with mitral stenosis in sinus rhythm

Propranolol reduces left atrial pressure at rest and during exercise in patients with mitral stenosis by lowering cardiac output and heart rate. Ten patients (aged 19-56) with moderate to severe isolated mitral stenosis were studied to determine whether propranolol increased their exercise tolerance. All were in sinus rhythm and free of left or right ventricular failure. Patients were trained in an individually graded bicycle or treadmill exercise protocol that provoked a reproducible degree of near maximal dyspnoea during the second three minute stage of exercise. Propranolol (80 mg or 120 mg) or matching placebo in two or three divided daily doses was given for one week in random double blind fashion. Exercise testing and questioning about subjective clinical response were carried out at the end of each week by an investigator who was unaware of the patient's heart rate. During propranolol treatment the heart rate was 19 beats/minute slower at rest and 38 beats/minute slower at peak exercise, but there was no change in mean exercise time to dyspnoea (274 s during propranolol vs 283 s during placebo). Four patients felt worse during the propranolol week, one patient felt better during the propranolol week, and five patients felt no difference between the two weeks. Propranolol did not improve objective or subjective exercise tolerance in patients with isolated mitral stenosis in sinus rhythm.     

Left atrial appendage function in patients with mitral stenosis in sinus rhythm.

AIMS: Left atrial appendage thrombi are believed to be the source of embolism in patients with rheumatic mitral stenosis in atrial fibrillation. There are a few studies which search the effects of left atrial appendage dysfunction in patients with mitral stenosis in sinus rhythm. METHODS AND RESULTS: Left atrial appendage function and flow patterns in 41 patients with rheumatic mitral stenosis in sinus rhythm and 11 healthy subjects were studied by transoesophageal echocardiography. Left atrial appendage flow profiles were recorded within the proximal third of the appendage. The left atrial appendage ejection fraction was expressed as (maximal area of appendage minimal area of appendage)/maximal area of appendage. In addition, two-dimensional imaging was used to determine the presence of spontaneous echocardiographic contrast and thrombus formation. Patients with mitral stenosis in sinus rhythm had significantly decreased left atrial appendage emptying and filling velocities compared to controls (0.40+/-0.15m/s vs 0.82+/-0.19 m/s and 0.42+/-0.21 m/s vs 0.68+/-0.28, respectively, P<0.001 and P<0.05). Compared with the control subjects, patients with mitral stenosis had significantly greater maximal area of the appendage and had reduced left atrial appendage ejection fraction (5.3+/-2.2 cm(2) vs 2.4+/-0.5 cm(2) and 50+/-16% vs 70+/-7%, respectively, P<0.001 and P<0.05). Of the patients with mitral stenosis in sinus rhythm, seven patients had spontaneous echocardiographic contrast and one of these had left atrial appendage thrombus. Compared with patients without spontaneous echocardiographic contrast, patients with spontaneous echocardiographic contrast had decreased left atrial appendage ejection fraction (33+/-21% vs 54+/-13%,P <0.01). One of the patients with mitral stenosis had central retinal artery occlusion, but thrombus was not observed in left atrial appendage. CONCLUSION: The study found that left atrial appendage dysfunction may occur in patients with mitral stenosis in sinus rhythm.     

A study of spontaneous echo contrast in patients with rheumatic mitral stenosis and normal sinus rhythm: an Indian perspective.

OBJECTIVE--To study the incidence of spontaneous echo contrast in left atrium of Indian patients with rheumatic mitral stenosis in normal sinus rhythm and to define its relations. SUBJECTS--Transthoracic and multiplane transoesophageal echocardiographic studies were performed in 89 consecutive patients with rheumatic mitral stenosis who were in normal sinus rhythm. RESULTS--Spontaneous echo contrast in the left atrium was seen in 57.3% of patients on multiplane transoesophageal echocardiography and in only 5.6% on transthoracic echocardiography. The mean mitral valve area was 1.07 (SD 0.33) cm2 and 1.32 (0.45) cm2 (P = 0.004), mean left atrial size was 4.27 (0.67) cm and 3.91 (0.5) cm (P = 0.029), mean diastolic pressure gradient was 12.64 (5.69) mm Hg and 10 (5.5) mm Hg (P = 0.049), and absence of mitral regurgitation was seen in 45% and 23% of patients respectively (P = 0.1). Among patients with spontaneous echo contrast, 31% had either left atrial/appendage thrombus or a history of embolism, upsilon 0% in patients without spontaneous echo contrast (P < 0.0001). CONCLUSIONS--There is a high incidence of spontaneous echo contrast in the left atrium in Indian patients with rheumatic mitral stenosis in normal sinus rhythm on multiplane transoesophageal echocardiography. These patients are likely to embolise or form thrombi in the left atrium. The presence of spontaneous echo contrast is also associated with significantly smaller mitral valve area, larger left atrium, and higher mean diastolic mitral pressure gradient.     

Quadrileaflet stentless mitral valve replacement

BACKGROUND: The study evaluates clinical results and hemodynamic parameters one year after implantation of a stentless quadrileaflet mitral valve (QMV). METHODS: Since August 1997 28 patients received the QMV, patient age was 69 +/- 8 years; 13 had predominant mitral stenosis and 15 incompetence, preoperative NYHA functional class was III or IV and cardiac index 1.8 +/- 0.6 L/min/m2. RESULTS: Surgery was performed using a conventional (25) or a minimally invasive approach (3). 20 patients received a medium and 8 a large-size prosthesis, crossclamp time was 58 +/- 19 min. Additional procedures were myocardial revascularization in four, tricuspid repair in two, and left-atrial radiofrequency ablation to restore sinus rhythm in six patients. Perioperative mortality (1) was not valve-related. All other patients were discharged on time. At postoperative, 6-, and 12-months follow-up mean transvalvular pressure gradients were 4.2 +/- 1.5 / 4 +/- 0.9/ 3.8 +/- 1.4 mmHg and mitral valve orifice area index was 1.5 +/- 0.3 / 1.6 +/- 0.3 / 1.6 +/- 0.4, NYHA class was I or II. CONCLUSIONS: The QMV is well suited for mitral valve replacement. The anulo-ventricular continuity is preserved and the QMV function resembles native mitral valve function. If its performance is maintained in the long term the QMV may be the mitral prosthesis of choice.     

Exercise ventilation after balloon dilatation of the mitral valve.

BACKGROUND--Exertional dyspnoea is a limiting symptom in many patients with mitral stenosis but its causes remain incompletely understood. Ventilation during exercise is abnormal in chronic heart failure of all causes and there is increased ventilatory cost of carbon dioxide production. PATIENTS--23 patients with rheumatic mitral stenosis undergoing percutaneous balloon dilatation of the mitral valve were studied to investigate exercise ventilation. METHODS--Treadmill exercise tests with respiratory gas analysis were performed before and 1 day, 7 days, and 10 weeks after balloon dilatation of the mitral valve. The relation between ventilation (VE) and production (VCO2) was analysed by linear regression. RESULTS--The VE/VCO2 slope was linear in all patients and before balloon dilatation of the mitral valve it correlated inversely with peak minute oxygen consumption (VO2) (rs = -0.47, P < 0.05), exercise duration (rs = -0.66, P < 0.01), and mitral valve area (rs = -0.5, P < 0.05). The VE/VCO2 slope declined acutely after balloon dilatation of the mitral valve (n = 10) (mean (SD) 41 (4) v 36 (2.9), P < 0.05) and did not change again thereafter. At 10 weeks (n = 23) exercise duration (460 (230) v 630 (240) s, P < 0.01) and peak VO2 (12.7 (4.3) v 14.9 (4.8) ml/kg/min, P < 0.05) increased significantly. CONCLUSIONS--Patients with rheumatic mitral stenosis have a similar increase in the VE/VCO2 slope to that of patients with heart failure from other causes. Successful balloon dilatation of the mitral valve is associated with an acute reduction in the exercise VE/VCO2 slope.     

心脏再同步化治疗慢性心力衰竭伴持续性心房颤动的疗效

目的评价心脏再同步化治疗(CRT)慢性心力衰竭(简称心衰)合并持续性心房颤动(简称房颤)患者的临床疗效。方法选择慢性心衰患者53例,其中42例窦性心律患者及11例房颤患者接受双心室起搏治疗,术后3个月进行随访,观察患者的心功能分级,6 min步行距离,超声心动图测定各房室腔内径大小、左室射血分数(LVEF)、二尖瓣返流以及速度向量成像超声评价同步性参数的变化。结果 53例三腔起搏器置入术均取得成功。与术前相比,术后3个月房颤CRT患者心功能分级(2.30±0.47级vs 3.0±0.02级)、左房内径(44.9±3.8 mm vs52.2±4.2 mm,P<0.05),LVEF(0.43±0.02 vs 0.32±0.03)及二尖瓣返流(1.5±0.2 vs 3.18±1.75,P<0.01)均有明显改善,速度向量成像超声结果显示,室内不同步较术前有明显改善。窦性心律患者术后各项心功能及不同步指标较术前亦有明显改善,与房颤CRT患者比较差异无显著性。结论对于慢性心衰合并持续性房颤患者,CRT与窦性心律一样可以改善心功能。     

Response of the right ventricle to exercise in isolated mitral stenosis

Eight patients in sinus rhythm, with varying degrees of isolated mitral stenosis (mitral valve area 0.6 to 1.3 cm2 and total pulmonary vascular resistance 5.0 to 17.5 U-m2), underwent supine rest and symptom-limited exercise radionuclide ventriculography to determine right ventricular (RV) and left ventricular ejection fraction (EF). Cardiac catheterization with hemodynamic measurements at rest and at peak exercise was performed within 24 hours of radionuclide ventriculography. Four of the 8 patients underwent corrective mitral surgery resulting in normal mean pulmonary artery pressures and total pulmonary vascular resistance at rest. These 4 patients had repeat radionuclide ventriculography at rest and during exercise 1 to 2 months after surgery. Preoperatively, all 8 patients had an abnormal exercise RVEF response (mean change +/- standard deviation [SD], -5.0 +/- 4.5%), coincident with an increase in mean pulmonary artery pressure during exercise (mean change, 15 +/- 5.0 mm Hg). The change in RVEF from rest to exercise, corrected for duration of exercise, correlated with peak exercise mean pulmonary artery pressure (r = -0.71, p = 0.05), as well as total pulmonary vascular resistance at rest (r = -0.82, p = 0.02). Postoperatively, all 4 patients who underwent surgical correction showed a normal RVEF response during exercise (mean change +/- SD, +6.8 +/- 4.0%). Thus, in patients with acquired mitral stenosis and no coronary artery disease (1) loading conditions and not contractility are prime determinants of RV exercise response, and (2) an exercise-induced decrease in RVEF may be a sensitive marker for increased total pulmonary vascular resistance and pulmonary hypertension.     

Effect of percutaneous transvenous mitral commissurotomy for the preservation of sinus rhythm in patients with mitral stenosis

OBJECTIVES: Atrial fibrillation is frequently associated with mitral stenosis and is considered to be an unfavorable factor for the long-term prognosis. The efficacy of percutaneous transvenous mitral commissurotomy(PTMC) was examined for the preservation of sinus rhythm in patients with mitral stenosis after PTMC. METHODS: Long-term clinical data after PTMC were obtained from 71 patients who had undergone PTMC from March 1989 to September 1999. Eighteen patients in sinus rhythm before PTMC were divided into two groups: the SR group(n = 5) who remained in sinus rhythm, and the Af group(n = 13) who showed change from sinus rhythm to persistent or paroxysmal atrial fibrillation after PTMC. RESULTS: Age, sex, mitral valve area(1.4 +/- 0.3 vs 1.2 +/- 0.3 cm2), mean mitral pressure gradient(14.3 +/- 5.5 vs 12.6 +/- 5.9 mmHg), mean left atrial pressure(15.9 +/- 7.6 vs 19.0 +/- 7.7 mmHg), left ventricular end-diastolic pressure(7.5 +/- 2.8 vs 9.3 +/- 3.9 mmHg), left ventricular end-diastolic volume index(77 +/- 13 vs 82 +/- 14 ml/m2), left ventricular ejection fraction(60 +/- 6% vs 55 +/- 4%) and cardiac output(5.1 +/- 0.4 vs 4.9 +/- 0.8 l/m2) before PTMC were not different between the two groups. Changes in mean mitral pressure gradient, mean left atrial pressure and cardiac output immediately after PTMC were not different statistically. Mitral valve area immediately after PTMC was significantly greater in the SR group compared to the Af group(2.3 +/- 0.3 vs 1.8 +/- 0.3 cm2, p < 0.05). The change in mitral valve area was also greater in the SR group(1.0 +/- 0.2 vs 0.6 +/- 0.4 cm2, p < 0.05), but there was no statistical difference in the percentage change of mitral valve area between before and immediately after PTMC(SR group 78 +/- 35% vs Af group 50 +/- 35%). End-diastolic pressure, end-diastolic volume index and ejection fraction immediately after PTMC were not statistically different. CONCLUSIONS: The final mitral valve area immediately after PTMC in the patients with mitral stenosis in sinus rhythm, but not the changes of mean mitral pressure gradient, mean left atrial pressure or cardiac output, is important for the maintenance of sinus rhythm.