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.     

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.     

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.     

Partial left atriectomy in the treatment of atrial fibrillation associated with mitral valve disease]

BACKGROUND: Atrial fibrillation is frequently observed under conditions associated with atrial dilatation. Atrial size is a factor related to the genesis and maintenance of atrial fibrillation. Predictive parameters of persistence of atrial fibrillation after maze procedure are atrial size and long duration of atrial fibrillation. The aim of this study was to investigate the effects of surgical left atrial reduction in chronic atrial fibrillation by mitral valvulopathy. PATIENTS AND METHOD: nineteen patients with chronic atrial fibrillation and dilated left atrium undergoing mitral valve procedures were included in this prospective study: group I with left atrial reduction (10 patients) and group II including control (9 patients). Both groups were with similar preoperative characteristics. RESULTS: At the mean follow-up of 12 months, all the patients in group II had chronic atrial fibrillation, and 7 patients in group I showed in atrial rhythm (p < 0.003). The patients in whom atrial fibrillation continued after surgery showed left atrial area of 33.8 +/- 12.3 cm2 and a volume of 98.5 +/- 53.9 ml; and the patients with normal rhythm had a left atrial area of 24.5 +/- 5.3 cm2 and a volume 60.3 +/- 21.2 ml. CONCLUSIONS: Preliminary results indicate that surgical left atrial reduction in patients with chronic atrial fibrillation may be a mechanism implicated in the elimination of arrhythmia after surgery.     

Clinical and echocardiographic predictors of left atrial clot and spontaneous echo contrast in patients with severe rheumatic mitral stenosis: a prospective study in 200 patients by transesophageal echocardiography

The objective of this study was to prospectively investigate various clinical and echocardiographic variables to predict the left atrial and left atrial appendage clot and spontaneous echo contrast in patients with severe rheumatic mitral stenosis. We studied 200 consecutive patients (112 males and 88 females; mean age 29.6+/-9.6 years). Left atrial clot and spontaneous echo contrast were present in 26 and 53.5% of cases, respectively. There were no significant differences in the mitral valve area, mean transmitral diastolic gradient and left ventricular ejection fraction between patients with and without clot. Patients with clot were older (34.4+/-11.4 vs. 28.2+/-8.5 years, P<0.001), had longer duration of symptoms (41. 4+/-36.0 vs. 28.8+/-22.9 months, P<0.001), more frequent atrial fibrillation and spontaneous echo contrast (69.2 vs. 16.9%, P<0. 00001 and 76.9 vs. 45.3%, P<0.00001, respectively) and larger left atrial area and diameter (41.0+/-12.7 vs. 29.9+/-7.4 cm(2), P<0.00001 and 53.9+/-8.3 vs. 47.6+/-7.4 mm, P<0.0001, respectively) as compared to patients without clot. Similarly patients with spontaneous echo contrast were older (31+/-10.4 vs. 27.8+/-8.3 years, P<0.01), had more frequent atrial fibrillation (48.6 vs. 9.7%, P<0.0001), left atrial clot (37.4 vs. 12.9%, P<0.0001), larger left atrial area and diameter (37.6+/-11.2 vs. 28.1+/-6.7 cm(2), P<0.00001 and 52.2+/-8.3 vs. 45.9+/-6.5 mm, P<0.00001, respectively) and smaller mitral valve area (0.77+/-0.14 vs. 0.84+/-0.13 cm(2), P<0.01) as compared to patients without spontaneous echo contrast. There were no significant differences in the mean transmitral diastolic gradient and left ventricular ejection fraction. On multiple regression and discriminant function analysis, atrial fibrillation and left atrial area were independent predictors of left atrial clot formation. In a subgroup of patients with sinus rhythm, larger left atrial area and presence of spontaneous echo contrast were significantly associated with the presence of clot in left atrium and appendage. We conclude that in patients with severe mitral stenosis, the presence of atrial fibrillation and in the subgroup of the patients with sinus rhythm the presence of large left atrium (> or =40 cm(2)) and spontaneous echo contrast were associated with higher risk of clot formation in the left atrium and might be benefited by prophylactic anticoagulation.     

Stunning of the left atrium after pharmacological cardioversion of atrial fibrillation

INTRODUCTION: Stunning of the left atrium and atrial appendage is a well known but not fully clarified phenomenon observed during the cardioversion of atrial fibrillation regardless of the cardioversion method attempted. AIM: To assess the effects of propafenone and amiodarone on left atrium and left atrial appendage contractility. METHODS: Forty patients with paroxysmal atrial fibrillation (20 females, 20 males), aged 60-83 (mean 72.0+/-10.1) years, were enrolled into the study. Half of these patients had sinus rhythm restored by the administration of oral propafenone (150-300 mg) and the remaining 20 patients were treated with intravenous amiodarone (150-450 mg). The control group consisted of 20 patients (10 females, 10 males) aged 52-78 (mean 61.2+/-9.3) years with sinus rhythm and no history of atrial fibrillation. All the patients had a transthoracic (TTE) and transesophageal (TEE) echocardiography performed while still in the AF, before drug administration and 1 hour after sinus rhythm restoration. RESULTS: All haemodynamic parameters of the left atrium measured after the sinus rhythm restoration were significantly worse when compared with the control group. Left atrial fractional shortening and total atrial fraction were significantly lower after propafenone than amiodarone (8.6+/-3.6% vs 11.7+/-5.5%, p<0.05; and LA FC 16.2+/-5.3% vs 23.3 (+/-6.3)% respectively, p<0.05). Doppler echocardiographic parameters included in the analysis such as mitral flow and superior left pulmonary vein flow were significantly lower in the sinus rhythm restoration group than in the control group. Among them the end-diastolic mitral flow velocity amplitude and flow velocity integral as well as the maximum pulmonary retrograde velocity were significantly worse in the group treated with propafenone than in patients receiving amiodarone. All the atrial appendage Doppler velocity parameters were significantly reduced after the sinus rhythm restoration in both groups. In the patients treated with propafenone, values of these parameters were significantly decreased compared with the patients receiving amiodarone. CONCLUSIONS: Successful pharmacological cardioversion of atrial fibrillation causes the left atrium and left atrial appendage contractility impairment similar to that observed with other methods of the sinus rhythm restoration. Following the AF cardioversion the level of left atrial stunning is higher in the patients treated with propafenone than in subjects receiving amiodarone.     

风心病慢性房颤心外膜标测心房有效不应期的对比研究

目的:研究风心病慢性房颤的电生理特征。方法:对29例风心病伴或不伴慢性房颤的病人在行二尖瓣置换术时,采用心外膜标测技术测定左、右心房各部位的有效不应期(AERP)及右房内和房间的传导时间。结果:风心病慢性房颤组左、右心房AERP比窦性心律明显缩短(P<0.05),左、右心房各部分的AERF,之间有明显差异(P< 0.01),即存在明显离散性;慢性房颤组的右房和房间传导时间在转复为窦性心律和缩短刺激右房高位问期时均显著长于正常对照组(P<0.05)。结论:风心病慢性房颤心房各部位AERP的差异反映了其AERP的离散性,而AERP 的离散性在房颤的诱发和维持过程中起着重要作用。     

Effects of left atrial ablation of atrial fibrillation on size of the left atrium and pulmonary veins

OBJECTIVES: The purpose of this study was to determine the effect of left atrial circumferential ablation on the size of the left atrium and pulmonary veins (PVs). BACKGROUND: The long-term effects of left atrial circumferential ablation on left atrial and PV size and anatomy have not been analyzed in quantitative fashion. METHODS: PV and left atrial sizes were analyzed in 41 consecutive patients (mean age 54 +/- 12 years) with paroxysmal (n = 25) or chronic (n = 16) atrial fibrillation. Computed tomography of the chest with three-dimensional reconstruction was performed before and 4 +/- 2 months after left atrial circumferential ablation. Left atrial circumferential ablation was performed to encircle the PVs 1 to 2 cm from the ostia, using a power output of 70 W. Additional ablation lines were created in the posterior left atrium and mitral isthmus. Radiofrequency energy also was delivered within the circles and at the PV ostia in 51% of patients at a reduced power output of 35 W. RESULTS: At 6 months, 36 patients (88%) were in sinus rhythm without antiarrhythmic drug therapy, including 3 patients (7%) who developed persistent left atrial flutter and underwent subsequent successful ablation of atrial flutter. There was a 15 +/- 16% decrease in left atrial volume (P < .01) and 10 +/- 35% decrease in PV ostial area (P < .01), without focal narrowing, in patients with a successful outcome. Focal PV stenosis did not occur in any of the 41 patients. CONCLUSIONS: Maintenance of sinus rhythm after left atrial circumferential ablation is associated with reduced left atrial and PV ostial size. Left atrial circumferential ablation for atrial fibrillation does not cause PV stenosis.     

Increased plasma levels of soluble P-selectin in rheumatic mitral stenosis

BACKGROUND: Previous studies have demonstrated that platelet activation occurs in peripheral blood of patients with rheumatic mitral stenosis (MS). However, in patients with MS, the plasma level of soluble P-selectin (a marker of platelet activation) remains unsettled. METHODS AND RESULTS: A total of 20 patients with symptomatic MS undergoing percutaneous transluminal mitral valvuloplasty (PTMV) were studied (group 1; 16 patients in permanent atrial fibrillation, and 4 patients in sinus rhythm). The plasma levels of soluble P-selectin in the femoral vein and artery, and right and left atria before PTMV and those in the peripheral venous blood at the 1-week and 4-week follow-ups after PTMV were determined by solid-phase, sandwich, enzyme-linked immunosorbent assay. The mitral valve area was calculated by means of the Doppler pressure half-time method. In addition, we measured plasma concentrations of soluble P-selectin in the peripheral venous blood samples obtained from 22 control patients (including 14 healthy volunteers in sinus rhythm [group 2] and 8 patients in permanent lone atrial fibrillation [group 3]). The plasma levels of soluble P-selectin were significantly elevated in group 1 patients (49.78 +/- 37.72 ng/mL) [mean +/- SD] compared with group 2 (25.52 +/- 15.38 ng/mL) and group 3 patients (32.17 +/- 14.18 ng/mL) [p < 0.005]. In group 1 patients, the plasma levels of soluble P-selectin in the left atrium did not significantly differ from those in the right atrium, femoral vein, or femoral artery (p = 0.05). The area of mitral valve increased significantly after PTMV (1.06 +/- 0.17 cm(2) vs 1.48 +/- 0.32 cm(2), p < 0.0001). The mean left atrial pressure fell significantly and immediately after PTMV (23.0 +/- 5.1 mm Hg vs 17.6 +/- 5.9 mm Hg, p < 0.0001). The peripheral venous plasma levels of soluble P-selectin obtained before PTMV did not significantly fall after PTMV (before, 49.8 +/- 37.7 ng/mL; 10 min after, 39.8 +/- 19.1 ng/mL; 1 week after, 46.1 +/- 20.8 ng/mL; and 4 weeks after, 41.2 +/- 15.9 ng/mL; p = 0.145). CONCLUSIONS: The venous plasma levels of soluble P-selectin in patients with moderate-to-severe MS were significantly higher than those in healthy volunteers or patients with lone atrial fibrillation. In addition, in patients with MS, there was no difference in the plasma levels of soluble P-selectin between the left and right atrial blood and between peripheral and atrial blood. Moreover, there was no change in soluble P-selectin levels as a result of PTMV.     

Atrial size reduction as a predictor of the success of radiofrequency maze procedure for chronic atrial fibrillation in patients undergoing concomitant valvular surgery

INTRODUCTION: Previous studies showed that the surgical maze procedure can restore sinus rhythm and atrial transport function in patients with chronic atrial fibrillation (AF). However, no previous studies discussed the association of atrial size reduction and the success of sinus conversion by the radiofrequency (RF) maze procedure for chronic AF. METHODS AND RESULTS: A total of 119 chronic AF patients undergoing valvular operations were included in this study. Sixty-one patients received RF and cryoablation to create lesions in both atria to simulate the surgical maze II or III procedure (RF maze II or RF maze III; 13 patients, group 1) or a modified maze pattern (RF maze "IV"; 48 patients, group 2). The other 58 patients who underwent valvular operations alone without the maze procedure served as control (group 3). At 3-month follow-up after operation, sinus rhythm was restored in 73%, 81%, and 11% of patients in groups 1, 2 and 3, respectively. Preoperative left and right atrial sizes were not statistically significant predictors of sinus conversion by the RF maze procedure. However, as a result of postoperative reduction of atrial sizes, postoperative left atrial diameter was significantly smaller in patients who had sinus conversion by the RF maze procedure than in patients who did not regain sinus rhythm (45.0+/-7.0 mm vs 51.0+/-8.0 mm; P = 0.03). Postoperative right atrial area of patients who had sinus conversion by the RF maze procedure also was significantly smaller than that of patients who did not regain sinus rhythm (18.1+/-4.4 cm2 vs 28.5+/-8.2 cm2; P = 0.008). CONCLUSION: Atrial size reduction appears to predict the success of sinus conversion with the RF maze procedure used in conjunction with valvular surgery.     

Increased circulating endothelin-1 in rheumatic mitral stenosis: irrelevance to left atrial and pulmonary artery pressures

BACKGROUND: Increased plasma endothelin (ET)-1 concentrations have been observed in patients with rheumatic mitral stenosis (MS). However, the mechanisms of increased circulating ET-1 in patients with MS remain unclear. METHODS: We measured plasma concentrations of ET-1 in blood samples from the femoral vein and artery, and right and left atria obtained from 20 patients with moderate-to-severe rheumatic MS before and after percutaneous transluminal mitral valvuloplasty (PTMV) [group 1; 16 patients in chronic atrial fibrillation and 4 patients in sinus rhythm]. In addition, we measured plasma concentrations of ET-1 in the peripheral venous blood samples obtained from 22 control patients (including 14 healthy volunteers in sinus rhythm [group 2] and 8 patients in chronic lone atrial fibrillation [group 3]). Plasma ET-1 concentrations were measured by solid-phase, sandwich enzyme-linked immunosorbent assay. RESULTS: The peripheral venous plasma concentrations of ET-1 were significantly higher in group 1 patients (2.46 +/- 0.90 pg/mL) than in group 2 and group 3 patients (0.74 +/- 0.42 pg/mL and 0.99 +/- 0.41 pg/mL, respectively [mean +/- SD]; p < 0.0001). However, there was no significant difference in the peripheral venous concentrations of ET-1 between group 2 and group 3 patients. In group 1 patients, the plasma ET-1 concentration in the femoral vein (2.46 +/- 0.90 pg/mL) was significantly higher than that in the right atrium (2.02 +/- 0.69 pg/mL), left atrium (2.11 +/- 0.99 pg/mL), and femoral artery (2.05 +/- 0.75 pg/mL) [p = 0.0001]. The plasma ET-1 concentration in the femoral vein was not correlated with the mean left atrial pressure (r = 0.05; p = 0.838) and mean pulmonary artery pressure (r = 0.07; p = 0.757). The plasma ET-1 concentration in the left atrium was also not correlated with the mean left atrial pressure (r = 0.11; p = 0.656), mean pulmonary artery pressure (r = 0.06; p = 0.788), or mitral valve area (r = 0.02; p = 0.936). Although the area of mitral valve increased significantly (1.06 +/- 0.17 cm(2) vs 1.48 +/- 0.32 cm(2); p < 0.0001), and the mean left atrial pressure (23.0 +/- 5.1 mm Hg vs 17.6 +/- 5.9 mm Hg; p < 0.0001) and mean pulmonary arterial pressure (31.0 +/- 7.9 mm Hg vs 25.5 +/- 7.0 mm Hg; p < 0.001) fell significantly and immediately after PTMV, there were no significant changes in the plasma ET-1 concentrations in the femoral vein, right atrium, left atrium, and femoral artery immediately after PTMV. CONCLUSION: Increased production of ET-1 in the pulmonary circulation in response to increased pulmonary artery pressure was not the mechanism of increased circulating ET-1 concentration in patients with MS. We proposed that one of the mechanisms of increased ET-1 concentration in the femoral vein was increased peripheral ET-1 release due to increased systemic venous pressure and mechanical damage of the endothelium.     

ECG dynamics at rest and during exertion after mitral commissurotomy]

Four degrees of left atrial electrical activity were identified by ECG made before and after closed mitral commissurotomy in 70 patients with mitral stenosis and sinus rhythm. The critical electrical activity of the left atrium and hypertrophy of the right ventricle along with the typical auscultation pattern of mitral stenosis were found to cardiographically correspond to critical stenosis of the left atrioventricular ostium in most cases. The area of the mitral orifice, which was attributable to that of the body, was 0.6 to 0.8 cm2/m2. The patients with critical left atrial electrical activity were considered to be at risk for atrial fibrillation in the immediate postoperative period.     

Atrial septal pacing to resynchronize atrial contraction and improve atrial transport function

OBJECTIVES: Atrial septal pacing via a trans-septal breakthrough site within the right atrial septum can shorten global atrial activation time, resulting in significant reduction of recurrence of atrial fibrillation events. This study examined whether this pacing method will lead to resynchronization of atrial contraction and its benefit on hemodynamic function can be maintained for 24 months. METHODS: Thirty patients with atrial fibrillation and delayed atrial conduction were enrolled (17 males, 13 females, mean age 73 +/- 7 years). Trans-septal breakthrough site within the right atrial septum was identified through pacing from the dorsal left atrium. Continuous atrial septal pacing at the trans-septal breakthrough site was performed for 24 months. Time difference (TD) between right and left atrial contractions was measured during atrial septal pacing and sinus rhythm by pulse Doppler echocardiography of the trans-tricuspid (P-At) and mitral (P-Am) blood flows (TD = P-Am - P-At). RESULTS: The atrial lead was screwed near the fossa ovalis in 29 of 30 patients. Atrial septal pacing yielded significantly shorter P wave duration (101.9 +/- 10.4 vs 139.6 +/- 14.7 msec, p < 0.001), leading to significant reduction of TD in atrial contraction (-8.8 +/- 10.0 vs 29.8 +/- 13.6 msec, p < 0.001)as compared to sinus rhythm. Both shorter P wave duration and reduced TD during atrial septal pacing remained statistically significant during the follow-up period as compared to sinus rhythm. Both left atrial diameter and A to E ratio of filling waves at mitral valve were significantly decreased at 12 months and remained decreased at 24 months. CONCLUSIONS: Atrial septal pacing at the trans-septal breakthrough site can resynchronize atrial contraction and results in improved hemodynamic effects during 24 months of follow-up.     

Myosin isoenzyme distribution in overloaded human atrial tissue

Using nondenaturing polyacrylamide gel electrophoresis, we have identified two distinct myosin isoenzymes in human atrial tissue that correspond to the V1 and V3 isomyosins found in rat ventricular tissue. Normal left and right atrial appendages have approximately 50% V3. When the left atrium was exposed to hemodynamic overload secondary to mitral stenosis, the percent V3 increased to 77 +/- 10% (n = 10); exposure to hemodynamic overload secondary to mitral regurgitation caused an increase to 70 +/- 14% (n = 6). Changes in the isoenzyme pattern were seen in the right atria of patients with mitral stenosis and markedly elevated pulmonary arterial pressures compared with control subjects and patients with mitral stenosis without severe pulmonary hypertension. Several clinical variables were examined to determine which factors might influence isoenzyme expression. Age, sex, the presence of atrial fibrillation, and pulmonary capillary wedge pressure did not predict the isoenzyme pattern. However, patients with mitral valvular disease and only slightly enlarged left atria tended to have a higher percent V3 than those with massively enlarged atria. These data confirm that human atrial tissue, like rat ventricular tissue, can alter its isomyosin composition in response to a hemodynamic load. The data further suggest that the isoenzyme shift is an early adaptation to the imposed load.     

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.     

Significance of atrial fibrillation, left atrial thrombus and severity of stenosis for risk of systemic embolism in patients with mitral stenosis

The prognostic significance of atrial fibrillation, left atrial thrombus and the severity of mitral stenosis (MS) for systemic embolism was evaluated in 142 consecutive patients with MS (male 61, female 81; mean age 51 +/- 10 years) who were referred for cardiac catheterization. The relationships between systemic embolization, atrial fibrillation, left atrial thrombus and the size of mitral valve area obtained by the echocardiographic or Doppler method, or cardiac catheterization (Gorlin's formula) were studied. The effects of mitral regurgitation (MR) (Sellers II < or =) on systemic embolism or left atrial thrombus were also evaluated. Atrial fibrillation was observed in 117 patients (87%), 30 (28%) of whom had a history of systemic embolism. Four of 18 patients (22%) with sinus rhythm had a history of systemic embolism. Left atrial thrombus was observed in 63 patients (45%), including 17 (27%) with a history of systemic embolism. Seventeen (22%) of 76 patients without left atrial thrombus had a history of systemic embolism. Left atrial thrombus was detected in 17 of 41 (41%) patients with severe MS [mitral valve area (MVA) < or = 1.0 cm2], 8 of 25 (32%) patients with moderate MS (1.1 < MVA < or = 1.5 cm2), 2 of 14 (14%) patients with mild MS (MVA > or = 1.6 cm2), and embolization was complicated in 11% of cases of severe MS, 32% of cases of moderate MS and 21% of cases of mild MS. There was no significant difference between the 3 groups. Left atrial thrombus was more frequently observed in patients without MR than with MR (44% vs 13%, p < 0.05), but there was no significant difference in the incidence of embolism between the groups (28% vs 22%). Positive therapy intervention should be considered to prevent systemic embolism regardless of the presence or absence of sinus rhythm, MR, left atrial thrombus or severity of stenosis.     

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.     

Evaluation of bilateral pulmonary vein isolation for the treatment of atrial fibrillation: value of postoperative electrophysiological study.

OBJECTIVE: To evaluate electrophysiological changes after bilateral pulmonary vein isolation in patients undergoing mitral valve surgery and to relate the clinical outcome at 1-year follow-up with the results of the postoperative electrophysiological study. METHODS: Prospective study of patients with atrial fibrillation undergoing bilateral pulmonary vein isolation using radiofrequency energy and concomitant mitral valve surgery. Pulmonary vein isolation was performed with a heptapolar catheter. Each set of up to 7 simultaneous applications aimed at a maximal duration of one minute and a maximal preset temperature of 70 degrees C. Energy delivery (< 150 watts) was controlled by thermosensors located on each electrode. Before hospital discharge, all patients presenting sinus rhythm underwent an electrophysiological study, using epicardial pacing wires placed during surgery. Isolated areas were compared to the non-isolated left atrium with respect to electrogram amplitudes and atrial capture thresholds. At one-year follow up, cardiac rhythm was assessed in all patients and correlated with the results of the postoperative electrophysioloical study. RESULTS: The study population consisted of 20 patients with mitral valve disease (mean age 59 +/- 11 years), chronic atrial fibrillation present for 0.5 to 18 years and dilated left atria (55 +/- 11 mm assessed by M-mode echocardiography). The radiofrequency procedure added, on average, 7 minutes (3 to 17) to the duration of the mitral valve surgery. No patient died or suffered surgical complications. Eleven patients presented sinus rhythm before hospital discharge. The electrogram amplitude inside the isolated zones was less than 25% of that in nonisolated areas (0.3 +/- 0.2 mV versus 2.1 +/- 1.7 mV, p = 0.002). Atrial capture thresholds were significantly higher for the isolated areas (13.5 +/- 9.3 mA versus 8.5 +/- 4.0 mA; p < 0.05). At one-year follow-up, nine patients maintained atrial fibrillation, nine remained in sinus rhythm and two lost sinus rhythm to atrial fibrillation. In both these patients, the reduction in electrogram amplitude inside the isolated zones was similar to that of the remaining patients discharged in sinus rhythm. However, postoperative electrophysiological studies in these patients showed that atrial capture thresholds for isolated areas had not increased significantly (8 mA and 6 mA, respectively). CONCLUSION: Rhythm at discharge after bilateral pulmonary vein isolation tends to remain at one-year follow up. Radiofrequency-induced modifications in electrogram amplitudes may be less important than increases in pacing thresholds of isolated zones with respect to maintenance of sinus rhythm.     

M2 and M3-muscarinic acetylcholine receptors remodelling in patients with a dilated atrium

BACKGROUND: Studies have shown that autonomic tone plays an important role in the pathogenesis of atrial fibrillation (AF) and remodelling of I(K, ACh) in chronic AF serves as a compensatory mechanism for the AF. The relation between atrial size and AF has been established. We investigated the remodelling of muscarinic receptors in patients with dilated atrium and assessed the relationship between the muscarinic receptor remodelling and the dilated atrium. METHODS: A small piece of the tip of the right atrial appendage was obtained from 19 patients in sinus rhythm (SR), 28 patients with mitral stenosis and 10 patients with chronic AF (AF > 6 months). Western-blot was used to determine the expression of M2 and M3 receptors. RESULTS: Patients with mitral stenosis and chronic AF had a larger left atrial diameter than patients in SR. The densities of the M2 receptor in patients with mitral stenosis (with AF and with SR) and chronic AF were lower than that in patients with SR (0.54 +/- 0.08 vs. 0.29 +/- 0.06, 0.26 +/- 0.05 and 0.28 +/- 0.06, P < 0.05). However, the densities of the M3 receptor in patients with mitral stenosis and chronic AF were higher than that in patients with SR (0.07 +/- 0.01 vs. 0.18 +/- 0.02, 0.17 +/- 0.01 and 0.15 +/- 0.01, P< 0.05). Furthermore, there was no significant difference in M2 and M3 receptors between AF and SR in patients with mitral stenosis. CONCLUSION: Remodelling of M2 and M3 receptors is not associated with AF, but with the dilated left atrium.     

Atrial fibrillation: how effectively can sinus rhythm be restored and maintained after balloon mitral valvotomy?

Atrial fibrillation, commonly associated with rheumatic mitral stenosis, worsens the prognosis. We studied the efficacy of achieving and maintaining sinus rhythm in patients with chronic atrial fibrillation who underwent a successful balloon mitral valvotomy. Fifty-four patients (26 men, 28 women; age 36+/-8 years) received amiodarone 200 mg thrice daily in the first week, and thereafter a maintenance dose of 200 mg once daily. Electrical cardioversion was attempted at 1 and 3 months and patients were followed up at 6, 12 and 18 months. At the end of 1, 3, 6, 12 and 18 months 81 percent, 72 percent, 60 percent, 54 percent and 49 percent of patients, respectively, were in sinus rhythm. Only one patient had a severe adverse effect (hypothyroidism). Univariate analysis revealed that lower age, shorter duration of atrial fibrillation and smaller left atrial size was associated with successful restoration to sinus rhythm. On multivariate analysis, the duration of atrial fibrillation was the only significant predictor of long-term maintenance of sinus rhythm. Amiodarone seems safe and reasonably effective in restoration and maintenance of sinus rhythm in patients of atrial fibrillation with rheumatic heart disease.