Yoshio Kosakai

Cox maze procedure for chronic atrial fibrillation associated with mitral valve disease.

Between April 1992 and October 1993, we combined a modified maze procedure with mitral valve repair (n = 26) or replacement (n = 36) in 62 patients with atrial fibrillation, including 16 patients undergoing reoperation. Associated procedures included aortic valve operation (n = 22), tricuspid annuloplasty (n = 28), atrial plication (n = 10), and others (n = 3). Duration of atrial fibrillation varied from 0.1 to 23 years (average 8.3 +/- 6.4 years), the f-wave voltage ranged from 0 to 0.45 mV (0.16 +/- 0.09 mV), and cardiothoracic ratio varied from 46% to 85% (64% +/- 9%). We modified the maze atriotomies to preserve the sinus node artery and used cryoablation to simplify procedures. Aortic crossclamp time was 142 +/- 25 minutes and cardiopulmonary bypass time 226 +/- 34 minutes. No early or late deaths occurred in a total of 783 patient-months of follow-up. In 52 patients (84%) who regained atrial rhythm, an atrial A-wave was detected in 84% for transtricuspid flow and in 71% for transmitral flow. One patient with sinus rhythm had an episode of transient neurologic ischemia 4 months after mechanical valve implantation. The 10 patients who remained in atrial fibrillation had preoperative fibrillation for a significantly longer time than the rest of the patients with atrial rhythm (14.8 versus 7.2 years p < 0.001) and a larger left atrial dimension (70 versus 58 mm, p < 0.01). Nonetheless, no variable alone could have predicted postoperative rhythm for individual patients. The results suggest that the maze procedure is safe and effective and therefore should be considered for patients with chronic atrial fibrillation undergoing mitral valve operations.

Risks and Benefits of Combined Maze Procedure for Atrial Fibrillation Associated With Organic Heart Disease

OBJECTIVES This study sought to identify the risks and benefits of adding the maze procedure in patients with atrial fibrillation (AF) undergoing operation for underlying organic cardiac disorders. BACKGROUND Persistent AF often leaves patients symptomatic even after otherwise successful cardiac surgery. METHODS Fifty-one patients undergoing valvular operation and the maze procedure (n = 43) or repair of congenital anomalies (n = 8) combined with the maze procedure were compared with 51 patients (control group) matched for underlying diseases and procedures except for the maze operation. Each group, including 31 patients with a concomitant tricuspid annuloplasty and 12 undergoing reoperation, were similar in age, duration of arrhythmia, degree of cardiomegaly and New York Heart Association functional class. RESULTS Patients undergoing the maze procedure had longer cardiopulmonary bypass time (213 vs. 144 min, p < 0.0001), longer cardiac arrest (134 vs. 93 min, p < 0.0001) and greater blood loss with longer respiratory care (39 vs. 18 h p = 0.021) and intensive care unit stay but no mortality. No significant differences were found in catecholamine or transfusion requirements immediately after operation. Sustained AF was much less frequent in the maze group (12% at 1 year) than the control group (86%, p < 0.0001), with an average follow-up period of 32 months (range 25 to 42). Atrial contraction was documented in 41 (80%) and 40 (78%) patients for right and left ventricular filling, respectively, after the maze procedure, resulting in a significantly smaller cardiac size and improved functional capacity. Medication was discontinued in seven patients in the maze group compared with two in the control group. CONCLUSIONS Improved restoration of atrial rhythm and contraction with combined maze operation appeared to justify the increased operative time and complexity and postoperative care.

Modified Maze Procedure for Patients With Atrial Fibrillation Undergoing Simultaneous Open Heart Surgery

BACKGROUND Persistent atrial fibrillation (AF) leaves patients symptomatic and at increased risk of thromboembolism even after otherwise successful cardiac surgery. METHODS AND RESULTS To treat AF secondary to cardiac lesions requiring surgery, we combined a modified maze procedure in 101 patients simultaneously undergoing valvular procedures (87), repair of congenital anomalies (12), and other procedures (2), including 24 repeat operations. Duration of AF varied from 0.1 to 30 years (average +/- SD, 8.8 +/- 7.0 years); the f-wave voltage ranged from 0 to 0.45 mV (0.15 +/- 0.09 mV); and cardiothoracic ratio varied from 40% to 99% (63 +/- 9%). Aortic cross-clamp time varied from 75 to 229 minutes (138 +/- 31 minutes), with bypass time ranging from 119 to 326 minutes (217 +/- 42 minutes). There were two early deaths (2%), no late deaths, and one episode of transient neurological ischemic attack in follow-up ranging from 1.0 to 3.1 years, for a total of 190 patient-years. Postoperative rhythms were sinus in 83 patients (82%), junctional in 4 (4%), and persistent AF in 14 (14%), each of whom had mitral valve disease. Patients with other underlying pathology had complete recovery of atrial rhythm. A normal-sized A wave was detected in 88% for transtricuspid flow and in 73% for transmitral flow, suggesting concomitant recovery of atrial contraction. Among 36 patients without mechanical valves, 30 (83%) with atrial rhythm and contraction have been taken off anticoagulation therapy, including 10 who are free of all medication. CONCLUSIONS The results suggest that the combined approach is safe, effective, and indicated in patients who are judged capable of tolerating the procedure and likely to regain atrial rhythm.

The electrophysiologic mechanism of ST-segment elevation in Brugada syndrome.

OBJECTIVES We sought to demonstrate the electrophysiologic (EP) mechanism of the ST-T change in Brugada syndrome. BACKGROUND Brugada syndrome is characterized by various electrocardiographic manifestations (e.g., right bundle branch block, ST-segment elevation, and terminal T-wave inversion in the right precordial leads) and sudden cardiac death caused by ventricular fibrillation. Direct evidence in support of the EP mechanism underlying this intriguing syndrome has been lacking. METHODS Monophasic action potentials (MAPs) were obtained from three patients with the coved-type ST-segment elevation (Brugada patients) and five control patients using the contact electrode method. Epicardial MAPs were recorded during open-chest surgery in all patients. RESULTS A spike-and-dome configuration was documented from epicardial sites of the right ventricular (RV) outflow tract in all Brugada patients but not in control patients. Monophasic action potential recordings from the endocardium with special focus on the RV outflow tract could not demonstrate any morphological abnormalities in three Brugada patients. CONCLUSIONS The presence of a deeply notched action potential in the RV epicardium, but not in endocardium, would be expected to induce a transmural current that would contribute to elevation of the ST-segment in the right precordial leads. The spike-and-dome configuration may also prolong the epicardial action potential, thus contributing to a rapid reversal of the transmural gradients and inscription of an inverted T-wave.

Mode of onset of ventricular fibrillation in patients with Brugada syndrome detected by implantable cardioverter defibrillator therapy

OBJECTIVES We sought to demonstrate the mode of spontaneous onset of ventricular fibrillation (VF) in patients with Brugada syndrome. BACKGROUND The electrophysiologic mechanisms of VF in Brugada syndrome have not been fully investigated. METHODS Nineteen patients (all male, mean age 47 +/- 12 years) with Brugada syndrome were treated with an implantable cardioverter defibrillator (ICD). The implanted devices were capable of storing electrograms during an arrhythmic event. We investigated the mode of spontaneous onset of VF according to the electrocardiographic features during the episode of VF, which were obtained from stored electrograms of ICDs and/or electrocardiographic (ECG) monitoring. RESULTS During a follow-up of 34.7 +/- 19.4 months (range 14 to 81 months), 46 episodes of spontaneous VF attacks were documented in 7/19 (37%) patients. The event-free period between ICD implantation and the first spontaneous occurrence of VF was 14.6 +/- 12.1 months (range 3.7 to 27.4 months). We investigated 33/46 episodes of VF, for which electrocardiographic features (10 to 20 s before and during VF) were obtained from ICDs and/or ECG monitoring in five patients. A total of 22/33 episodes of VF were preceded by premature ventricular contractions (PVCs), which were almost identical to the initiating PVCs of VF. Furthermore, in three patients who had multiple VF episodes, VF attacks were always initiated by the same respective PVC. The coupling interval of the initiating PVCs of VF was 388 +/- 28 ms. CONCLUSIONS Spontaneous episodes of VF in patients with Brugada syndrome were triggered by specific PVCs. These findings may provide important insights into the pathophysiological mechanisms causing VF in Brugada syndrome.

Atrial natriuretic peptide secretion and body fluid balance after bilateral atrial appendectomy by the maze procedure

OBJECTIVES One of the earliest recognized postoperative complications of the maze procedure was the fluid retention in the immediate postoperative period. Routine postoperative administration of diuretics markedly reduces the frequency and severity of the fluid retention. However, the cause of the abnormal fluid balance is still uncertain. METHODS We evaluated 24 patients: 15 patients underwent the maze procedure (maze group) and 9 patients did not (nonmaze group). Blood samples were obtained before and in the time course after operation for atrial natriuretic peptide measurement. To evaluate the influence of atrial natriuretic peptide on the body fluid balance, we also measured the amount of body fluid balance and the total doses of furosemide and dopamine administered after operation. To examine the effect of the maze procedure on atrial natriuretic peptide secretion in chronic phase, we measured plasma atrial natriuretic peptide levels during dynamic exercise in 21 patients who had undergone cardiac operations 2 years before. RESULTS Plasma atrial natriuretic peptide levels in the nonmaze group significantly increased after operation. In contrast, plasma atrial natriuretic peptide levels in the maze group did not increase, and these levels were significantly lower than in the nonmaze group. Although significantly greater doses of furosemide and dopamine were administered to the maze group than to the nonmaze group, the body fluid balance in the maze group was comparable with that in the nonmaze group in the early postoperative period. The response of atrial natriuretic peptide secretion by exercise was significantly attenuated in the maze group (n = 12) compared with the nonmaze group (n = 9) even 2 years after surgery, although there were no significant differences in heart rate or blood pressure during exercise between two groups. CONCLUSIONS These results suggest that the maze procedure attenuates atrial natriuretic peptide secretion in the early postoperative period and persists in chronic phase. This attenuated atrial natriuretic peptide secretion may reduce the ability of the kidneys to handle fluid load early after surgery.

Improved success rate of the maze procedure in mitral valve disease by new criteria for patients’ selection

OBJECTIVE We have carried out the maze procedure for atrial fibrillation (AF) as a combined operation with mitral valve surgery in a consecutive fashion until December 1994 (period 1). Therefore, the success rate in sinus rhythm conversion remained unsatisfactory. We have selected the patients according to arbitrarily decided new criteria since January 1995 (period 2), and examined the results prospectively. METHODS Between May 1992 and February 1997, we carried out the maze procedure in 220 patients as a combined operation with mitral valve surgery. During period 2, we carried out the maze procedure in 63 cases who satisfied all the new criteria (voltage of f-wave in V1 lead > 0.1 mV, cardiothoracic ratio (CTR) < 70%, LA dimension < 70 mm), and 37 patients out of these criteria. Success was defined as sinus rhythm restoration without sick sinus syndrome. RESULTS There were 4 hospital deaths (1.8%) and 4 late deaths (1.8%). Success rate was significantly (P = 0.0089) higher in period 2 (82%) than in period 1 (65%). Success rate was significantly higher in patients within criteria than out of criteria both in period 1, period 2, and total (77 versus 48%, P = 0.018; 90 versus 66%, P = 0.004, and 83 versus 55%, P = 0.0001). CONCLUSION The maze procedure is highly reliable when combined with mitral valve surgery if patients are selected properly.

Plasma atrial natriuretic peptide concentration inversely correlates with left atrial collagen volume fraction in patients with atrial fibrillation: plasma ANP as a possible biochemical marker to predict the outcome of the maze procedure.

OBJECTIVES We hypothesized that the plasma atrial natriuretic peptide (ANP) level reflects atrial degenerative change and may predict the outcome of the maze procedure. BACKGROUND Although a larger preoperative left atrial dimension and longer duration of atrial fibrillation (AF) have been reported in patients with persistent AF than in those with sinus rhythm (SR), these individual factors were not enough to predict the outcome of the maze procedure. METHODS Preoperative plasma ANP levels were measured in consecutive 62 patients who underwent the Kosakais modified maze procedure. Moreover, we performed histological and molecular biological examinations in the resected left atrial tissues. RESULTS The preoperative plasma ANP was lower in the AF group (n = 13) than it was in the SR group (n = 49) (p < 0.001). Multiple logistic regression analysis revealed that duration of AF and plasma ANP were independently associated with postoperative cardiac rhythm. Among 41 patients with a higher plasma ANP or shorter duration of AF than the median value, SR was restored in 95% of patients. In contrast, in 21 patients with a lower plasma ANP and a longer duration of AF than the median value, SR was restored only in 48% of patients. Histological examination revealed that the collagen volume in the left atrial tissue was higher in AF than it was in SR and inversely correlated with plasma ANP. In addition, the messenger RNA expressions of ANP, collagen type I and type III were lower in AF than they were in SR. CONCLUSIONS These results suggest that a combination of plasma ANP and/or duration of AF may predict the success rate for the maze operation. Advanced atrial degenerative change may result in a decrease of atrial ANP secretion.

Surgical Treatment of Behcet's Disease Involving Aortic Regurgitation

BACKGROUND Behçets disease involving aortic regurgitation is rare, and prosthetic valve detachment after aortic valve replacement is one of the most serious complications reported. We investigated the surgical results in 10 patients with aortic regurgitation caused by Behçets disease. METHODS Between 1981 and 1997, 10 patients with aortic regurgitation secondary to Behçets disease had surgery. There were 8 men and 2 women, and their ages ranged from 33 to 60 years (mean, 46+/-8 years). The surgical procedures for aortic regurgitation were aortic valve replacement in 6 patients and Bentall type operation in 4. RESULTS No patient died during the hospital stay. The follow-up periods ranged from 11 to 185 months (mean, 87 months). Two patients died during the follow-up period. The acturial survival rate was 89% at 5 years and 67% at 10 years. Prosthetic valve detachment or suture detachment requiring redo operation occurred in 4 patients, 3 of whom had redo operations twice. Four patients had a composite graft replacement, and 1 patient died after the operation. No prosthetic valve detachment was noted in 64% of the patients at 5 years and in 43% at 10 years. CONCLUSIONS The rate of prosthetic valve detachment was 40% (4 of 10 patients), with a higher incidence in patients with Behçets disease than in those treated during the same period at the same hospital for aortitis caused by other diseases. Surgical techniques for treatment of this condition should be modified to improve the surgical outcome in these patients.

Ten-year experience with the Carpentier-Edwards pericardial xenograft in the tricuspid position.

We reviewed the cases of 66 patients who underwent 67 tricuspid valve replacements with Carpentier-Edwards pericardial xenografts between April 1985 and January 1994. Average patient age at time of operation was 52 years (range 8 to 71 years). Concomitant mitral or aortic valve replacements were performed in 46 patients. There were 10 operative deaths and 6 late deaths. Actuarial survival at 9 years was 75.4% +/- 5.7%. Prosthetic valve endocarditis occurred twice in one patient. Reoperations for tricuspid regurgitation and for concomitant procedures (maze operation and repair for leak of the mitral prosthesis) were performed in two patients. In both cases, examination of the explanted prostheses showed that the tricuspid regurgitation was the result of nonstructural dysfunction caused by fibrous pannus formation on the cusps of the ventricular side. Among the survivors, 47 patients (92%) were in functional class I or II. Prosthetic valve function was studied by color Doppler echocardiography. Among 38 patients, tricuspid regurgitation more than grade 3/4 or transprosthetic gradient more than 5 mm Hg was found in 11. One patient had right heart failure and the others had no symptoms. In 10 years of experience with the Carpentier-Edwards pericardial xenograft, mortality and morbidity after tricuspid valve replacement were satisfactory. Echocardiographic examination revealed subclinical prosthetic dysfunction in 35% of patients who were followed up for longer than 5 years, however, and we believe that these patients should receive careful follow-up.