Radial approach: a new concept in surgical treatment for atrial fibrillation. II. Electrophysiologic effects and atrial contribution to ventricular filling

Modified radial v/s biatrial maze for atrial fibrillation in rheumatic valvular heart surgery

BACKGROUND

Atrial fibrillation (AF) is commonest sustained atrial arrhythmia producing high morbidity. Although Cox's Maze III procedure cures AF in majority, reduced atrial transport function (ATF) is a concern. Radial approach with ablation lines radial from sinus node towards atrioventricular annulii and parallel to atrial coronary arteries, has shown better ATF.

METHODS

Single blind open randomized prospective study of 80 patients was undertaken in two groups (40 each) of modified Cox's maze III and modified radial approach, to evaluate conversion to normal sinus rhythm (NSR) and ATF. Patients undergoing surgery for rheumatic valvular heart disease with continuous AF were prospectively randomized. Ablation lines were created with radiofrequency (RF) bipolar coagulation with cryoablation for the isthmal lesions and coronary sinus. Results were compared at 6 months and ATF was evaluated by atrial filling fraction (AFF) and A/E ratio on echocardiography.

RESULTS

The rate of conversion to NSR in both groups was statistically insignificant by Fisher's exact test (p > 0.05). ATF was better in modified radial approach compared to modified Cox's Maze III (A/E compared by unpaired t test:0.52 ± 0.08 v/s 0.36 ± 0.10; p < 0.05. AFF compared using Mann Whitney U test: median AFF for radial group was 23 v/s 20 for biatrial group; p < 0.05).

DISCUSSION

In patients with AF undergoing rheumatic valvular surgery, radiofrequency radial approach is as effective as modified Cox's maze III for conversion to NSR with better atrial transport function.

Cardiac function in relation to rhythm outcome after intraoperative epicardial left atrial cryoablation

Objectives

To assess the effects of intraoperative left atrial epicardial cryoablation on rhythm and atrial and ventricular function.

Design

Thirty five patients with coronary artery disease and documented atrial fibrillation underwent coronary artery bypass surgery and concomitant cryoablation. An age and gender matched control group of 35 patients with atrial fibrillation underwent bypass surgery alone. Echocardiography was performed 9 ± 32 days before and 22 ± 6 months after surgery.

Results

The proportion of patients in sinus rhythm at follow-up was 63% and 34% (p = 0.04) in the cryoablation and control groups, respectively. In patients with sinus rhythm both before surgery and at follow-up, the left atrial area increased (p = 0.002) and the mitral annular excursion during atrial contraction decreased (p = 0.01) after cryoablation. The mitral flow velocity during atrial systole decreased after cryoablation (p = 0.002). The LV diameter increased (p = 0.03) and the left ventricular ejection fraction (LVEF) decreased (p = 0.03) in cryoablated but not in control patients. Continued deterioration was seen in patients with atrial fibrillation both pre- and postoperatively.

Conclusions

At long-term follow-up, a significantly higher proportion of patients was in sinus rhythm in the cryoablation than in the control group. The atrial and ventricular function had decreased at follow-up two years after surgery. This decrease was small and occurred within or close to the reference values in patients with sinus rhythm at follow-up, while patients remaining in atrial fibrillation showed a significant continued deterioration. Some subgroups were small, and the findings, although statistically significant, should be interpreted with caution.

Effects of Stepwise Ablation of Chronic Atrial Fibrillation on Atrial Electrical and Mechanical Properties

OBJECTIVES

This study sought to evaluate the effects of stepwise catheter ablation of chronic atrial fibrillation (AF) on atrial electrical and mechanical properties.

BACKGROUND

Although stepwise catheter ablation of chronic AF is associated with acute arrhythmia termination and a favorable clinical outcome, atrial tissue damage following the procedure has not been evaluated.

METHODS

Forty patients who had previously undergone catheter ablation of chronic AF were studied. In the index procedure, termination of AF was achieved by catheter ablation alone in 36 of 40 patients (90%). Electroanatomical mapping was performed in sinus rhythm > or =1 month after the index procedure, during which the surface area of scar (bipolar voltage of <0.05 mV), low-voltage tissue (<0.5 mV), and atrial propagation were evaluated. Left atrial (LA) mechanical function was assessed by transthoracic echocardiography.

RESULTS

Electroanatomical mapping showed areas of scar and low-voltage accounting for 31% +/- 12% and 32% +/- 17% of the total LA surface area respectively, with the ablated pulmonary vein region accounting for 20% +/- 4% of the LA surface area. The area of scar outside the pulmonary vein region represented 14% +/- 12% of the LA surface area using the initial randomized ablation strategy, and 6% +/- 8% (p = 0.02) using a specific ablation strategy. Atrial conduction was diversely affected by ablation with a wide range of LA conduction times observed (range 100 to 360 ms). The LA contraction was shown in all patients by the presence of late diastolic mitral flow (37 +/- 15 cm/s) and a mean LA active emptying fraction of 18 +/- 11%. At 9 +/- 5 months of follow-up, 39 patients (98%) were in sinus rhythm.

CONCLUSIONS

Stepwise ablation achieving sinus rhythm in patients with chronic AF has a significant impact on LA electrical activity but is associated with recovery of LA function.

Current strategies in the surgical treatment of atrial fibrillation: review of the literature and Onze Lieve Vrouw Clinic's strategy

Atrial fibrillation is the most common rhythm disturbance in clinical practice. It is a major source of stroke and morbidity. Although the Cox maze procedure effectively eliminates atrial fibrillation in most patients, the procedure has not found widespread application. As a consequence, new operations that use alternative sources of energy, such as radiofrequency, microwave, cryothermy, laser, and ultrasound have emerged to surgically create lesion sets to treat atrial fibrillation. This article reviews the fundamentals and current strategies in the surgical treatment of atrial fibrillation.

Catheter ablation of atrial fibrillation

Following the advent of the surgical maze procedure, several catheter techniques have been developed to provide permanent prophylaxis against atrial fibrillation. These noninvasive techniques work by compartmentalizing the atria, by ablating the arrhythmogenic foci, or by isolating the atria from these foci. Although still at an early stage of development, preliminary results using focal ablation and circumferential ablation show extreme promise.

Epicardial microwave application in chronic atrial fibrillation surgery

The search for alternative epicardial energy sources in the treatment of nonvalvular atrial fibrillation (AF) is a relatively new aspect of the evolving spectrum of Maze operations. We tested the hypothesis that epicardial microwave ablation produces identical results to those of the standard cryosurgical Maze. Fourteen consecutive patients with chronic AF underwent on-pump epicardial Maze procedures after routine cardiac surgery. The results were compared with those of 14 control patients selected from our Maze database of 280 patients. There were no differences in age, sex, cardiothoracic ratio, duration of AF, pump time, intensive care unit or hospital stays. The aortic cross clamp time with epicardial microwave was, however, shortened from 110 to 65 minutes (p=0.011). The recurrence rate of AF after discharge showed no significant difference between the two groups (14% vs. 15%, p=0.841). Epicardial microwave ablation might be a valuable alternative to the conventional cryosurgical Maze procedure, especially for those patients without associated mitral valve disease.

Surgical treatment of atrial fibrillation with argon-based cryotechnology

Over the past several years numerous attempts have been made to treat atrial fibrillation surgically. The most effective of all such surgical treatments has been the Maze operation, developed by James Cox in the 1980s. The Maze operation has demonstrated excellent long-term results. The procedure is based on a complex surgical technique, thus is it not easily being reproduced by every surgeon. Different attempts have been made to simplify the original Maze technique. In 1999, the electrophysiologists at the authors’ institution outlined a lesion concept for left atrial ablation in the treatment of atrial fibrillation. In 387 patients, the authors used intraoperative radiofrequency ablation to cure AF. The results were comparable to the maze procedure. This concept was very effective but after a time period of 4 years in 1% of patients esophagus perforations occurred. In a quest to identify other energy sources to produce good ablation results with less possible complications, intraoperative cryoablation has been developed. In the following study conducted the authors were able to use a new flexible cryocatheter (Cryocath Surgifrost®). Sinus rhythm was achieved in 71% after a 1 year follow-up period with low morbidity and comparable mortality, which was due to the concomitant cardiac pathologies and operative procedures. In conclusion, thus far from this series of patients presented, the authors have demonstrated that cryoablation with Argon-cryotechnology is efficacious and safe.

Curative treatment of atrial fibrillation with intraoperative radiofrequency ablation: short-term and midterm results

OBJECTIVE

This report describes the early and midterm results after intraoperative radiofrequency ablation of atrial fibrillation for patients with isolated chronic atrial fibrillation or atrial fibrillation in combination with additional valvular and nonvalvular cardiac diseases.

METHODS

From August 1998 to March 2001, a total of 234 patients with chronic atrial fibrillation underwent isolated intraoperative radiofrequency ablation alone (n = 74, 31.6%) or in combination with other cardiac procedures, such as mitral valve reconstruction (n = 57, 24.4%), mitral valve replacement (n = 38, 16.2%), aortic valve replacement (n = 11, 5.1%), coronary artery bypass grafting (n = 8, 5.0%), or a combination of the last with other cardiac procedures (n = 46, 19.7%). In all cases anatomic reentrant circuits confined within the left atrium were eliminated by placing contiguous lesion lines involving the mitral anulus and the orifices of the pulmonary veins through the use of radiofrequency energy application (exposure time, 20 seconds). A median sternotomy was used in 101 cases (43.2%), and video assistance through a right lateral minithoracotomy was used in 133 cases (56.8%).

RESULTS

A total of 188 patients (83.9%) were discharged in sinus rhythm, 17 patients (7.6%) had atrial fibrillation, and 19 patients (8.5%) had atypical flutter. Pacemakers were implanted in 23 patients (9.8%). There were 10 in-hospital deaths (4.2%), and 30-day mortality was 5 patients (2.1%). In 3 cases (1.3%) an atrioesophageal fistula developed, necessitating surgical repair. Six months' follow-up was complete for 122 (61.0%) of 200 patients, with 99 patients still in stable sinus rhythm (81.1%, 95% confidence interval 73.1%-89.9%). Twelve months' follow-up was complete for 80 (90.9%) of 88 patients, with 58 patients still in sinus rhythm (72.5%, 95% confidence interval 61.3%-83.2%).

CONCLUSIONS

Intraoperative radiofrequency ablation is a curative procedure for chronic atrial fibrillation. It is technically less challenging than the maze procedure and can be applied through a minimally invasive approach. Protection of the esophagus seems mandatory to avoid the deleterious complication of a left atrioesophageal fistula, such as was observed in 3 cases.

[Surgery ablation of atrial fibrillation with epicardial and endocardial biauricular radiofrequency: initial experience]

BACKGROUND

Atrial fibrillation is frequent in surgical patients with cardiac valvulopathies. Radiofrequency energy applied by means of surgical probes permits the reproduction of atriotomies described in the maze surgical procedure for the ablation of atrial fibrillation in a fast, safe and efficient way. This study presents our initial experience in treatment of chronic atrial fibrillation through radiofrequency performed in patients with surgical cardiac valvulopathies.

PATIENTS AND METHOD

From June to November 2000, 10 patients, with surgical indications of valvulopathy, were intraoperatively treated through radiofrequency for its atrial fibrillation. Ablations were performed in the right auricle from the epicardium before starting extra corporeal circulation, and in the left auricle from the endocardium, while under circulation. Radiofrequency was applied through a surgical multielectrode probe.

RESULTS

Eight patients (80%) presented some type of postoperative arrhythmia, with relapse of paroxysmal fibrillation in 3 patients and flutter in another one. At discharge, none of the patients presented relapse of chronic atrial fibrillation. There was no in-hospital mortality. After a mean follow-up of 3 months (range 1-6), 8 patients (80%) have recovered and maintained sinus rhythm. Only one patient has re-established echocardiographic biatrial contraction.

CONCLUSIONS

Intraoperative radiofrequency has allowed us to perform the auricular lesions, in both auricles, in a simple way, with an initial effectiveness of 80%. Epicardial ablation of the right auricle was simple and safe. Although no patient presented relapse of chronic atrial fibrillation at hospital discharge, postoperative arrhythmias have continued to be the main postsurgical problem.

The effect of cardiomyoplasty on left atrial function in experimental canine models

BACKGROUND

Cardiomyoplasty utilizes the latissimus dorsi muscle to boost the failing ventricle. However, the mechanism for clinical improvement still remains controversial. We have previously shown that left ventricular contraction was improved in the long-term periods after cardiomyoplasty in the normal canine heart model and in the dilated failing heart model. On the other hand, right ventricular filling was impaired if a rapid volume loading test was employed in the long-term period after cardiomyoplasty. The purpose of the present study was to determine whether cardiomyoplasty impairs the left atrial function and affects ventricular filling.

METHOD

Eleven mongrel dogs that had undergone cardiomyoplasty (study group, n = 5) or a sham operation (control group, n = 6) were studied for 12 weeks postoperatively. An IV 4.5% albumin solution (10 mL/kg) was infused into the right atrium, and hemodynamic changes in right cardiac catheterization and left atrial volume (LAV) were obtained by two-dimensional echocardiography. Atrial function was assessed by hemodynamic changes in Doppler echocardiography and hormonal changes.

RESULTS

Stroke volume was significantly increased, from 17.0 +/- 4.4 to 21.1 +/- 7.0 mL, respectively, before and 15 min after albumin infusion in the control group (p < 0.05). Heart rate and cardiac output were significantly increased, from 131.2 +/- 18.1 to 152.0 +/- 9.8 beats/min and 2.72 +/- 1.29 to 4.03 +/- 1.67 L/min, respectively, before and 15 min after albumin infusion in the study group (p < 0.05). No changes were observed in mean right atrial pressure and pulmonary capillary wedge pressure. LAV and atrial natriuretic peptide (ANP) levels increased significantly, from 5.8 +/- 2.1 to 8.5 +/- 3.8 mL and 22.5 +/- 7.5 to 44.5 +/- 31.7 pg/mL, respectively, before and 15 min after albumin infusion in the control group (p < 0.05). In the study group, LAV and ANP levels were also increased, from 10.1 +/- 2.4 to 12.7 +/- 2.8 mL and 64.2 +/- 60.6 to 232.6 +/- 272.2 pg/mL, respectively, before and 15 min after albumin infusion (p < 0.05). The peak velocities and the time-velocity integrals in the pulmonary venous flow of the systolic and diastolic waves, as well as their ratios (systolic to diastolic peak velocity ratio and systolic to diastolic time-velocity integral ratio) showed no significant differences between the two groups.

CONCLUSIONS

Cardiomyoplasty preserves left atrial filling and transport function; therefore, cardiomyoplasty may also activate ANP production by stimulating the atrium in the long-term period after cardiomyoplasty.

Long-term follow-up of atrial contraction after the maze procedure in patients with mitral valve disease

OBJECTIVES

We sought to determine the effectiveness of the maze procedure for maintaining sinus rhythm and atrial contraction for a long period in patients with mitral valve disease.

BACKGROUND

Although the maze procedure for atrial fibrillation (AF) has been effective in restoring sinus rhythm in patients with mitral valve disease, the long-term results of this procedure have not been determined.

METHODS

We echocardiographically studied 94 consecutive patients with mitral valve disease before, as well as early (3.1 +/- 3.3 months) and late (2.2 +/- 0.9 years) after, the maze procedure. Peak velocity and the time-velocity integral of the left ventricular (LV) diastolic filling wave during atrial contraction (A wave), as well as the atrial filling fraction (calculated as the ratio of the time-velocity integral of the A wave to total diastolic filling), were obtained from transmitral flow recordings. Peak A wave velocity > or =10 cm/s was considered to indicate echocardiographic evidence of effective atrial contraction.

RESULTS

Regular rhythm with P waves was restored in 70 patients (74%) in the early stage and in 59 patients (63%, p = 0.09) in the late stage after the maze procedure. Forty-seven patients (50%) in the early stage and 36 patients (38%, p = 0.14) in the late stage showed effective atrial contraction by Doppler echocardiography. Left atrial (LA) and LV end-diastolic diameters significantly decreased after the procedure (from 59 +/- 13 to 48 +/- 7 mm, p < 0.01; and from 54 +/- 9 to 47 +/- 5 mm, p < 0.01, respectively) and did not show significant changes during the follow-up period. Once atrial contraction was resumed, its degree did not change between the early and late stages after the maze procedure (17 +/- 6% vs. 17 +/- 6% for atrial filling fraction).

CONCLUSIONS

Sinus rhythm and atrial contraction recovered early after the maze procedure in most patients and were maintained for more than two years. Once active atrial contraction was resumed, the degree of contraction did not change thereafter. These results demonstrate that the maze procedure is effective for a long period in patients with mitral valve disease.

Modifications of the Cox-Maze III procedure

BACKGROUND

The extended operative time needed for surgery with complicated atrial incisions may preclude application of the Cox-Maze III procedure (CM-III) as a concomitant operation. And after the CM-III, left atrial (LA) contraction has been reported to recover in reduced magnitude compared with right atrial (RA) contraction.

METHODS

To decrease operative time, we have modified the CM-III (modification I) by: obliterating the LA appendage instead of excising it; cryoablating the bridge between the LA appendage and margin of the pulmonary vein encircling incision; extending the lateral incision of RA onto the RA appendage without excising it, and extending the incision more inferiorly toward the inferior vena cava; and omitting the T-incision of RA. We compared the clinical results of the conventional CM-III (group 1, n = 18) with those of the modified CM-III group (group 2, n = 23) performed in patients with rheumatic mitral valve (MV) disease. To enlarge the contractile area of the LA, we modified the CM-III to encircle the right and left pulmonary veins separately (modification II), and compared the LA contractilities of the conventional CM-III (group A, n = 15) with those of the second modification (group B, n = 9).

RESULTS

Modification I: Mean aortic cross-clamp (ACC) times (135 +/- 29 versus 104 +/- 18 minutes, p < 0.005) and cardiopulmonary bypass (CPB) times (240 +/- 33 versus 185 +/- 42 minutes, p < 0.001) were significantly decreased in group 2 compared with those in group 1. In group 1, sinus rhythm was restored in 16 patients (88.9%). RA contractility was demonstrated in 100% of patients with sinus rhythm (16 of 16) and LA contractility in 75% (12 of 16) in the latest follow-up echocardiography. In group 2, sinus rhythm was restored in 21 patients (91.3%). RA contractility was demonstrated in 100% of patients with sinus rhythm (21 of 22) and LA contractility in 76.2% (16 of 21). Modification II: Mean ACC times were increased in group B compared with group A (133 +/- 32 versus 172 +/- 39 minutes, p = 0.02). The A velocities at LA contraction and the ratio of atrial contraction to peak early diastolic filling velocity (A/E ratio) of the trans-mitral flow were 0.14 +/- 0.20 m/sec and 0.23 +/- 0.11 in group A, and 0.58 +/- 0.33 m/sec and 0.47 +/- 0.19 in group B, respectively, both showing a significant increase in group B compared with group A (p < 0.05).

CONCLUSIONS

Our first modification of the CM-III showed comparable sinus conversion rates and incidence of atrial contractility restoration with significantly shorter ACC and CPB times than the conventional CM-III. The second modification of the CM-III significantly increased the LA contractility when compared with the conventional CM-III, although the second modification required a longer ACC time.

Serial change in the atrial transport function after the radial incision approach

BACKGROUND

The left atrial transport function recovers slowly over several months after the maze procedure (Maze), but remains at a low level even during the long-term postoperative period. Because the Maze leaves an insufficient left atrial transport function, patients may still be prone to thromboembolism after the Maze. The radial incision approach (Radial) has been shown to preserve greater atrial transport function than does the Maze in the early postoperative period.

METHODS

To examine the serial change in the atrial transport function after the Radial, out of 32 patients who underwent the Radial, 15 patients were assessed by transthoracic Doppler echocardiography 1, 3, 6, and 12 months after surgery. The atrial filling fraction and peak A/E velocity ratio were determined from the flow-velocity spectra across the mitral and tricuspid valves. The incidence of thromboembolic events was examined in 21 patients who were followed for more than 3 months after the Radial. The data were compared with data obtained from 13 patients after (41 +/- 6 months) the Maze III procedure.

RESULTS

The left atrial transport function after the Radial increased within 3 months to a significantly greater level than did that after the Maze in the longterm. The atrial filling fraction was 28.2% +/- 7.9% at 3 months after the Radial and 15.1% +/- 4.0% at 41 months after the Maze (p < 0.01). The peak A/E ratio was 0.52 +/- 0.18 at 3 months after the Radial and 0.25 +/- 0.07 at 41 months after the Maze (p < 0.01). This increased atrial transport function was maintained for an extended period after the Radial. There were no thromboembolic events in any of the patients after the Radial or Maze, irrespective of postoperative anticoagulant therapy.

CONCLUSIONS

The Radial approach prevents thromboembolism by restoring sufficient atrial transport function more effectively and faster than does the Maze.

The maze III procedure for atrial fibrillation: should the indications be expanded?

BACKGROUND

We favor the maze III procedure over nonsurgical treatments for atrial fibrillation and have advocated addition of the maze in symptomatic patients with other compelling indications for cardiac surgery.

METHODS

Characteristics and perioperative outcomes of our 76 cumulative maze recipients between 1993 to 1998 were reviewed. The original maze III technique was employed without modification.

RESULTS

Isolated maze III was performed in 19 patients (25%) and combined with other procedures in 57 patients (75%), 49 of these involving one or more valves. Patients having combined procedures were taking fewer antiarrhythmics (p < 0.0001), but were older (p < 0.01), more often female (p < 0.05), and more often had chronic atrial fibrillation (p < 0.01) compared with isolated maze III recipients. The mean duration of aortic clamping and cardiopulmonary bypass for isolated maze was 69 +/- 11 and 145 +/- 22 minutes, and for combined valve procedures it was 122 +/- 38 and 205 +/- 47 minutes. There was no operative mortality. Complications occurred in 15 patients (19.7%). At 3 months atrial fibrillation was cured in 73 of 75 patients (97.3%). Sick sinus syndrome required pacemaker implantation in 3 patients (4.0%).

CONCLUSIONS

The maze III can be performed alone or as a combined procedure with equivalent success, and technical modifications may be unnecessary. A lower threshold for its expanded use in symptomatic patients with atrial fibrillation who require isolated or combined operations is appropriate.

Effect of atrial radiofrequency ablation designed to cure atrial fibrillation on atrial mechanical function

INTRODUCTION

The effects of linear radiofrequency lesions in the atria for cure of atrial fibrillation on atrial contraction have not previously been quantified.

METHODS AND RESULTS

Atrial function was measured before and 30 +/- 24 days after a biatrial ablation procedure designed to cure atrial fibrillation in eight dogs and after a sham procedure in three dogs. Atrial mechanical function was assessed using Doppler diastolic blood flow velocities, atrial systolic pressure wave amplitude, and assessment of atrial contribution to cardiac output estimated by comparison of AV sequential pacing to ventricular pacing at the same heart rate. The mitral Doppler A/E velocity ratio was 1.03 +/- 0.45 before and 0.72 +/- 0.43 after ablation (P = 0.048). The tricuspid A/E ratio was 0.88 +/- 0.17 before and 0.71 +/- 0.12 after ablation (P = 0.04). The estimated atrial contribution to cardiac output was 18% +/- 9% before and 5% +/- 4% after ablation (P < 0.01). The left atrial systolic pressure wave amplitude was 2.8 +/- 1.5 mmHg before and 1.7 +/- 1.0 mmHg after ablation (P = 0.1). These changes were not observed in control dogs. Lesions covered 25% +/- 6% of the atrial endocardial surface.

CONCLUSION

Multiple linear radiofrequency lesions in the atria designed to cure atrial fibrillation may impair atrial contractility. Reduced atrial function is partly due to loss of atrial myocardial mass, but regional delays in atrial activation and splinting of the atria by scarring also may contribute.

Initial experience with the radial incision approach for atrial fibrillation

BACKGROUND

Surgery for atrial fibrillation (AF) is performed with the aim of restoring sinus rhythm and atrial transport function, and preventing thromboembolism. The radial incision approach (RIA), in which the atrial incisions radiate from the sinus node toward the atrioventricular annular margins and parallel the coronary arteries, was developed as an outgrowth of and an alternative to the maze procedure in order to preserve a more physiological activation sequence and the atrial transport function.

METHODS

To determine whether the RIA is a promising procedure for AF, 23 patients who had undergone the RIA (n = 10) or the maze procedure (n = 13) for chronic AF associated with valvular heart disease were examined in terms of the postoperative cardiac rhythm and atrial transport function.

RESULTS

AF was cured in 90% of RIA patients and 92.3% of maze patients (not significant). One patient in each group required pacemaker implantation for an insufficient sinus rate postoperatively. The RIA was technically easier than the maze procedure, because the incisions were more linear and there was no isolation incision or "T-shape" incision in the left atrium. The left atrial transport function, assessed by transthoracic Doppler echocardiography, was greater after the RIA than after the maze procedure, while the right atrial transport function was equally preserved by both procedures. The peak atrial filling/early filling waves of the flow-velocity spectra across the mitral valve was significantly larger after the RIA than after the maze procedure (0.58+/-0.17 vs. 0.25+/-0.07, p<0.005). The left atrial filling fraction was significantly larger after the RIA than after the maze procedure (28.5%+/-5.0% vs. 15.1%+/-4.0%, p<0.001).

CONCLUSIONS

RIA provides a greater atrial transport function, and thus may represent a physiological alternative to the maze procedure as a surgical procedure for AF.

Radial approach: a new concept in surgical treatment for atrial fibrillation I. Concept, anatomic and physiologic bases and development of a procedure

BACKGROUND

The maze procedure cures atrial fibrillation; however, it isolates the pulmonary vein area and results in discordant activation in certain adjacent left atrial segments, which affects left atrial function. To preserve a more physiologic atrial transport function, we developed a new concept of surgical treatment for atrial fibrillation-the radial approach. The atrial incisions radiate from the sinus node toward the atrioventricular annular margins to allow a more physiologic atrial activation sequence and parallel the atrial coronary arteries to preserve blood supply to most atrial segments.

METHODS

We examined the atrial coronary arteries and the activation sequence during sinus rhythm in normal canine hearts to design the atrial incisions according to the concept of a radial approach.

RESULTS

The pattern of coronary artery distribution was centripetal, branching from the right coronary or left circumflex coronary artery at the right or left atrioventricular groove and spreading toward the sinus node. The endocardial mapping of the atria disclosed some important findings in designing the atrial incisions of the radial approach: the activation sequence at the left atrial septum and at the posterior left atrium between the pulmonary vein orifices. The atrial incisions were designed according to these findings.

CONCLUSIONS

The radial approach may represent a more physiologic atrial transport function.