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.     

Matrix metalloproteinases and atrial remodeling in patients with mitral valve disease and atrial fibrillation

BACKGROUND: Atrial fibrillation (AF) is associated with extracellular matrix remodeling involving atrial fibrosis and atrial dilatation. Angiotensin II mediated pathways and matrix metalloproteinases (MMPs) have been implicated in these processes. Our aim was to study atrial structural remodeling and the expression of the angiotensin receptor subtypes and MMPs and their inhibitors (TIMPs) in patients with mitral valve disease with and without AF. METHODS AND RESULTS: Biopsies from right and left atrial appendages (RA and LA) were taken from patients undergoing CABG (n=9, all in sinus rhythm (SR)) or mitral valve surgery (MVS; n=19; 9 with permanent AF and 10 in SR). Patients with MVS and AF had significantly larger atria (versus MVS and SR: p=0.02; versus CABG: p<0.01). The MVS patients had significantly more fibrosis than the control CABG group. Fibrosis was increased in both the AF and SR MVS groups in the LA, but only in the MVS-AF group in the RA. These AF patients had significantly more tricuspid regurgitation than SR patients. MMP-1 was down-regulated in LA of MVS patients (p=0.02) independent of the underlying rhythm (SR or AF; p=0.95). In RA biopsies, MMP-1 was down-regulated only in the MVS and AF group. MMP-9 was down-regulated in the MVS patients compared to CABG both in the RA and LA, and without a difference between the SR and AF groups. Protein expression of AT-1, AT-2, MMP-2, TIMP-1, -2 and -4, TNF-alpha, and TNF-alpha-converting enzyme did not differ significantly between the 3 groups. CONCLUSIONS: Concordant changes between MMP-expression and fibrosis during mitral valve disease, both in LA and RA, suggest involvement of MMPs in structural atrial remodeling. AF itself did not contribute to altered fibrosis or MMP-expression in the LA. The association between AF and RA changes may be precipitated by greater hemodynamic load due to tricuspid regurgitation in these patients.     

Right atrial myxoma with right to left shunting and mitral valve prolapse

A 58 year old black man presented with progressive dyspnea and persistent systemic arterial hypoxemia. Initial hemodynamic evaluation revealed mitral valve prolapse and evidence for isolated right to left shunting, presumed to be extracardiac. A detailed pulmonary evaluation disclosed normal volume and flow parameters with a mild reduction of the single breath carbon monoxide diffusing capacity. An open lung biopsy disclosed no abnormalities. Radionuclide studies of the heart, however, suggested the possibility of a filling defect in the right atrium, and echocardiography enforced the impression of a mass in the right atrium, subsequently demonstrated by superior vena cava angiography. Our report outlines the use of multiple diagnostic tools in difficult situations and stresses the importance of right atrial myxoma in the differential diagnosis of isolated right to left shunting.     

Predictors of left atrial thrombus in mitral valve disease

Objective:To determine the risk factors for left atrial thrombus (LAT) and the prevalence of thrombi in cases of mitral valve disease whose severity was fudged to necessitate surgical intervention. Design:Hospital record review of all operative cases from 1982 to 1985. Setting:A community serving a referral population encompassing 1.5 million people. Only two hospitals in the geographic area performed cardiac surgery, and both hospitals’ records were reviewed. Patients:All 372 patients who underwent either mitral valve replacement or open mitral commissurotomy. Main results:Twenty-six patients (7%) were noted to have LAT at surgery. Five preselected factors were significantly (p<0.05) associated with LAT in univariate analysis: female gender, prior history of embolism, prior anticoagulant therapy, mitral stenosis (MS), and atrial fibrillation (AF). In logistic regression analysis, only MS and AF remained as significant independent predictors of LAT. Mitral stenosis patients in sinus rhythm had a relatively low [2.4±3.3% (observed ±95% confidence interval)] likelihood of having an LAT. Likewise, mitral regurgitation patients in sinus rhythm (n=139)had an extremely low (0.7±1.4%) prevalence of LAT. In contrast, MS patients in AF (n=122)had a prevalence of LAT of 18.0±6.8%. Conclusions:These findings indicate that, overall, LAT in mitral valve disease may be less common than previous studies have suggested. In addition, mitral valve disease patients who remain in sinus rhythm appear to have a low risk of barboring an LAT. Conversely, MS patients, especially those in AF, appear to be at high risk of barboring an LAT. These results may be helpful in formulating strategies for the use of prophylactic anticoagulation in categories of patients with clinically severe mitral valve disease, or perhaps in estimating the likelihood of a cardiac source of embolism in mitral valve disease patients with suspected cerebral or peripheral emboli. Received from the General Medicine and Cardiology Units, Department of Medicine, the University of Rochester School of Medicine and Dentistry, Rochester, New York. Dr. Davison is currently at Washington University, St. Louis, Missouri.     

Impact of left atrial size reduction on chronic atrial fibrillation in mitral valve surgery

BACKGROUND AND AIM OF THE STUDY: Left atrial enlargement is a risk factor for the development of atrial fibrillation (AF). Large atrial size increases thromboembolic risk and reduces the success rate of cardioversion. The study aim was to evaluate if left atrial size reduction affects cardiac rhythm in patients with chronic AF undergoing mitral valve surgery. METHODS: Twenty-seven patients were analyzed prospectively. The left atrial incision was extended to the left inferior pulmonary vein. Left atrial size reduction was achieved by closure of the left atrial appendage from inside with a double running suture. The same suture plicated the left lateral atrial wall to the roof of the left pulmonary vein inflow and the inferior atrial wall. The atrial septum was plicated by placing stitches of the closing suture line across the fossa ovalis. Rhythm, neurological complications, cardioversion, anticoagulation and anti-arrhythmic medication were evaluated at one year postoperatively and at recent follow up (mean 40 +/- 15 months). RESULTS: At discharge, five patients (19%) were in sinus rhythm (SR). At one year postoperatively, SR was restored in 17 patients (63%), but five (19%) reported episodes of arrhythmia and AF persisted in 10 (37%). At recent follow up, four patients had died and three were lost to follow up. Among 20 patients examined, 13 (65%) had SR but six reported episodes of arrhythmia and AF persisted in seven (35%). LA diameter was significantly reduced, from 60.2 +/- 9.8 mm preoperatively to 44.5 +/- 7.0 mm at one year after surgery. CONCLUSION: The addition of left atrial size reduction to mitral valve surgery is technically simple, and was effective in 63% of patients with chronic AF, restoring predominant SR. In order to influence pathogenetic factors other than size, additional ablative steps may further increase the SR conversion rate. Size reduction may also improve the outcome of other ablative approaches.     

A study of embolism in mitral valve disease and atrial fibrillation

A number of possible risk factors, clinical, radiological, biochemical, and social have been examined in one group of 34 cases of mitral valve disease and four of lone atrial fibrillation, all of whom gave a history of embolism, and also in a group of 24 cases of mitral valve disease who gave no such history. All were on long-term anticoagulant treatment. Comparison of the two groups disclosed no features that would distinguish those who ran the greater risk of embolism from the remainder other than that the men in the former group were older and of shorter stature. At comparable age, the women with a history of embolism had smaller left atria. Examination of a special group of nine patients who had had embolism despite anticoagulant treatment also disclosed no special features, other than a greater age at the time of their first embolism. Fibrinolytic activity was less and the level of beta thromboglobulin was greater than normal in both groups. Those with proven risk of embolism were not distinguished by higher values of this platelet protein. Neither variable correlated with the type of heart disease. No positive association was found between cigarette smoking and the risk of embolism. Embolism was significantly more likely to occur between 0801 and 1600 hours than at other times of day.     

Ablation of atrial fibrillation with mitral valve surgery

PURPOSE OF REVIEW: Recent advances in understanding of the pathogenesis of atrial fibrillation and development of new technology have resulted in a surge of interest in the surgical ablation of atrial fibrillation, particularly in patients with mitral valve disease. For patients with both mitral valve dysfunction and atrial fibrillation, a variety of new approaches are available to enable a complete operation that includes both mitral valve repair and ablation of atrial fibrillation. The purposes of this review are to review the rationale for surgical ablation of atrial fibrillation (AF) in mitral valve patients, describe the classic Maze procedure and its results, detail new approaches to surgical ablation of AF, emphasize the importance of the left atrial appendage, and consider challenges and future directions in the ablation of AF in mitral valve patients. RECENT FINDINGS: Left untreated, atrial fibrillation increases mortality and morbidity in patients undergoing mitral valve surgery. While the Maze procedure effectively eliminates atrial fibrillation in most of these patients, its complexity and increased operative time has precluded widespread application. New operations that use alternative energy sources to create left atrial lesion sets ablate atrial fibrillation in 60 to 80% of patients having mitral valve surgery. SUMMARY: In mitral valve patients with atrial fibrillation of more than 6 months' duration, the operative strategy should include both mitral valve surgery and ablation of atrial fibrillation. In many cases, these procedures can be performed minimally invasively. Refinements in mapping and ablation technology are on the horizon, and these will facilitate more widespread application of minimally invasive approaches and further improve results.     

慢性心房颤动患者心房肌血管紧张素转换酶和血管紧张素受体mRNA表达改变的研究

目的研究慢性心房颤动(房颤)患者心房肌中血管紧张素转换酶(ACE)和血管紧张素受体AT1R、AT2RmRNA表达改变及其对房颤心房结构重构的影响。方法选取进行人工瓣膜置换术的风湿性心脏病房颤病人24例为研究组,风湿性心脏病窦性心律病人12例为对照组。上述病人术前均进行经胸超声心动图检查,于手术时取左心耳心肌标本,应用放射免疫法检测心肌组织中血管紧张素Ⅱ(AngⅡ)含量,采用RTPCR方法检测心房肌中ACE、AT1R、AT2R、及Ⅰ/Ⅲ型胶原(collagenⅠ/Ⅲ)各基因mRNA水平,并与超声指标作相关性分析。结果与对照组比较,房颤组左心耳心肌组织中AngⅡ含量显著增加(P<0.05);胶原Ⅰ、胶原Ⅲ、AT1R、AT2RmRNA的表达水平显著升高(P<0.05),并与房颤持续时间、左心房内径以及AngⅡ含量等指标具有显著相关性(P<0.05)。而ACEmRNA的表达无显著改变。结论慢性房颤患者心房肌局部肾素血管紧张素系统(RAS)激活参与了房颤时心房结构重构,是心房肌间质纤维化的主要机制。     

A study of embolism in mitral valve disease and atrial fibrillation.

A number of possible risk factors, clinical, radiological, biochemical, and social have been examined in one group of 34 cases of mitral valve disease and four of lone atrial fibrillation, all of whom gave a history of embolism, and also in a group of 24 cases of mitral valve disease who gave no such history. All were on long-term anticoagulant treatment. Comparison of the two groups disclosed no features that would distinguish those who ran the greater risk of embolism from the remainder other than that the men in the former group were older and of shorter stature. At comparable age, the women with a history of embolism had smaller left atria. Examination of a special group of nine patients who had had embolism despite anticoagulant treatment also disclosed no special features, other than a greater age at the time of their first embolism. Fibrinolytic activity was less and the level of beta thromboglobulin was greater than normal in both groups. Those with proven risk of embolism were not distinguished by higher values of this platelet protein. Neither variable correlated with the type of heart disease. No positive association was found between cigarette smoking and the risk of embolism. Embolism was significantly more likely to occur between 0801 and 1600 hours than at other times of day.     

Combined atrial fibrillation ablation with mitral valve surgery

BACKGROUND AND AIM OF THE STUDY: The study aim was to evaluate the efficacy and outcome of radiofrequency (RF) atrial fibrillation (AF) ablation in patients undergoing mitral valve (MV) surgery. METHODS: Between March 2002 and December 2004, 61 patients (mean age 65.4 +/- 10 years) underwent isolated endo-left atrial AF ablation using a unipolar RF device (Cardioblate; Medtronic, USA) in conjunction with 34 MV repairs and 27 MV replacements. AF was paroxysmal in 13 patients (21%), and permanent in 48 (79%), with a mean duration of 3.6 +/- 3.5 years. The etiology was degenerative in 35 patients (57%), rheumatic in 17 (28%), and ischemic in nine (17%). All patients received amiodarone postoperatively. RESULTS: No patients died during the study, and there were no thromboembolic complications. All patients had intraoperative conversion. Forty-one patients (67%) presented with postoperative relapse; definitive conversion was achieved in 34 (83%) cases within three months. The overall success rate was 75.4% at 14 +/- 8.8 months; success was greater in the MV repair group (85%) than in the MV replacement group (66.7%), though not significantly so (p = 0.09). Factors associated with definitive conversion included smaller left atrial size (p = 0.007), decreased left ventricular end-diastolic diameter (p = 0.04), and NYHA class I (p = 0.05). Age, AF duration and etiology were not associated with conversion, but associated coronary artery bypass grafting showed a strong trend towards significance (p = 0.07). In these patients, AF duration did not predict conversion to sinus rhythm. CONCLUSION: Combined AF ablation with MV surgery is safe and effective. Although AF ablation seems more beneficial with MV repair, the success rate may vary significantly according to patient characteristics.     

Beta adrenoceptor density and adenylate cyclase response in right atrial and left ventricular myocardium of patients with mitral valve disease

Beta adrenoceptor density, measured by radioligand binding techniques, is reportedly much higher in atrial than in ventricular myocardium of patients with mitral valve disease. In the present study adenylate cyclase activity, both basal and in response to beta adrenergic agonists and sodium fluoride, in biopsy preparations from these same patients was significantly lower in atrial than in ventricular tissue when stimulated with either isoproterenol, noradrenaline, isoproterenol combined with terbutaline, or sodium fluoride. Terbutaline stimulated and basal adenylate cyclase activity was not significantly different in the two cardiac regions. The ratios of receptor density to isoproterenol stimulated and to sodium fluoride stimulated adenylate cyclase activity were 4-5 times higher in atrial than in ventricular biopsy specimens. Thus ventricular beta receptors, although present in comparatively low concentrations, are coupled to considerably more catalytic moieties of the receptor-adenylate cyclase complex than their atrial counterparts. The reason for this is probably a relative lack of coupling proteins (N components) in atrial tissue. A weak positive correlation between receptor density and isoproterenol stimulated adenylate cyclase activity was found in atrial but not in ventricular tissue. This may indicate individual variation in receptor-adenylate cyclase coupling. Furthermore, no correlation was found between atrial and ventricular values for any variable. One reason for this may be the different haemodynamic stresses in the two cardiac chambers.     

Midterm results of left atrial bipolar radiofrequency ablation combined with a mitral valve procedure in persistent atrial fibrillation

Introduction

The aim of the study was to assess the midterm results of left atrial bipolar radiofrequency ablation combined with a mitral valve procedure in patients with mitral valve disease and persistent atrial fibrillation.

Methods

Between October 2006 and July 2009, 95 patients with mitral valve disease and persistent atrial fibrillation underwent a mitral valve procedure and left atrial bipolar radiofrequency ablation. The postoperative data of the combined procedure were collected at the time of discharge and at one, three, six and 12 months after the operation.

Results

Hospital mortality rate was 6.3% (six patients). Normal sinus rhythm was achieved in 77.2% of patients during the early postoperative period in hospital, and in 73.3, 72.0 and 75% of patients at three, six and 12 months postoperatively, respectively. Patients were followed up for a mean duration of 14.02 ± 5.71 months (range: 6–19 months). During this midterm follow-up period, nine patients had late recurrence of atrial fibrillation. No risk factor was identified for late recurrence of atrial fibrillation.

Conclusion

Our midterm follow-up results suggest that the addition of left atrial bipolar radiofrequency ablation to mitral valve surgery is an effective and safe procedure to restore sinus rhythm in patients with chronic atrial fibrillation.     

Atrial electrophysiological properties evaluated by right and left atrial pacing in patients with or without atrial fibrillation

Coronary sinus (CS) pacing has been shown to prevent induction of atrial fibrillation (AF) by suppression of the propensity of atrial premature beats at high right atrium (HRA) to induce local conduction delay at the posterior triangle of Koch. However, other mechanisms of CS pacing in preventing induction of AF have not been explored. This study investigated whether a differential conduction delay exists between the HRA and distal CS pacing in patients with paroxysmal AF but not in patients without AF. Nine patients with atrioventricular reentrant tachycardia utilizing a left accessory pathway undergoing catheter ablation were included in this study. Group 1 consisted of 5 patients with clinically documented paroxysmal AF and group 2 4 patients without a history of AF. The effective refractory periods (ERPs) of HRA, distal CS, and four different left atrial sites were determined. The interatrial conduction time and conduction delay between the HRA and distal CS during HRA or distal CS pacing were measured. The interatrial conduction delay (ICD) from the HRA to the distal CS during HRA pacing was significantly longer than that from the distal CS to the HRA during distal CS pacing in patients of group 1. However, the ICD from the HRA to the distal CS during HRA pacing was not significantly longer than that from the distal CS to the HRA during distal CS pacing in group 2 patients. A differential conduction delay between the HRA and the distal CS pacing is present in this specific population of patients with paroxysmal AF but not in patients without AF. The shorter conduction delay during DCS pacing may contribute to the prevention of induction of AF.     

Calcified left atrial myxoma with floppy mitral valve

A heavily calcified left atrial myxoma in a man aged 53 was diagnosed from the plain chest x-ray film and confirmed by echocardiography. There was also moderate mitral regurgitation caused by a floppy mitral valve. Before a systemic embolus is considered to have arisen from a floppy mitral valve, echocardiography must be performed.     

Electrophysiological properties in patients undergoing atrial compartment operation for chronic atrial fibrillation with mitral valve disease

AIMS: Surgical treatment for atrial fibrillation is now feasible inselective cases. The aim of this study was to assess the electrophysiologicalproperties of patients undergoing atrial compartment operationfor chronic atrial fibrillation. METHODS AND RESULTS: Electrophysiological studies were performed in 20 mitral valvepatients with atrial fibrillation who had been maintained insinus rhythm for more than 1 year after atrial compartment operation.Intra-cardiac recording and programmed electrical stimulationwere performed in various atrial compartments. The parametersstudied included sinus node function, atrial conduction andrefractoriness, atrioventricular conduction function and induciblearrhythmias if any. Intra-cardiac recordings showed that therhythm was of sinus origin in all cases, with the earliest atrialactivity located in the high right atrium. The mean sinus cyclelength was 750±110 ms, AH time 106±29 ms, andHV time 53±7 ms. The sinus node function was normal in18 patients (90%), and only two patients had prolonged sinusnode recovery and sino-atrial conduction. The right atrial appendagecompartment was driven by the sinus node in all patients. However,the conduction time from the high right atrium to the rightatrial append age compartment was markedly prolonged in 12 of15 patients (80%) undergoing the three-compartment operationin which an incision was placed between the high right atriumand right atrial appendage compartments. On the other hand,the electrical activities in the left atrial compartment weremuch more varied. In 13 of 20 patients (65%), the left atrialcompartment was driven by the sinus node; 11 of the 13 patientshad a normal or mildly prolonged conduction time (ranged 75to 146 ms), whereas two patients had a marked delay in conduction(200 ms and 266 ms, respectively). In the remaining seven patients,the left atrial compartments were dissociated from the restof the heart; five of them had a quiescent left atrium, onea fluttering left atrial rhythm, and one a slow left atrialrhythm. The effective refractory period was longer in the leftatrial compart ment (242±47 ms) as compared to that ofthe high right atrium (224±26 ms, P<0·01) andright atrial appendage compartments (219±25 ms, P<0·01).Programmed electrical stimulation could not induce atrial fibrillationin any patient, whereas two patients had inducible atrial flutterand three repetitive atrial responses. CONCLUSION: (1) Atrial compartment operation does not impair sinus nodefunction in most cases. (2) Elimination of atrial fibrillationwhile maintaining the electrical connection between differentatrial compartments is feasible.