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Ann Thorac Surg 1996;62:1118-1122
© 1996 The Society of Thoracic Surgeons

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Original Articles: Cardiovascular

Postoperative Cardiac Rhythms With Superior-Septal Approach and Lateral Approach to the Mitral Valve

Department of Cardiovascular Surgery, Kyushu University Hospital, Kyushu University, and Department of Cardiovascular Surgery, National Kyushu Medical Center Hospital, Fukuoka, Japan

Accepted for publication April 27, 1996.

	Abstract

Top Footnotes Abstract Introduction Methods Results Comment Addendum References

 
Background. The superior-septal approach provides an excellent view of the mitral valve and therefore has received considerable interest. However, the safety of this approach is controversial because it requires division of the sinus node artery in most cases.

Methods. Postoperative cardiac rhythms were analyzed in 152 consecutive patients who underwent mitral valve procedures between January 1992 and February 1995 with a conventional right lateral left atriotomy (group 1, n = 69) or the superior-septal approach (group 2, n = 83). Follow-up ranged from 2 to 38 months, and the mean follow-up was 16.1 months in group 1 and 13.8 months in group 2.

Results. The mortality rate was similar in the two groups (1.4% in group 1 and 1.2% in group 2), and the causes of death were not related to the left atriotomy. At discharge, 96% of the patients in group 1 who were in sinus rhythm preoperatively and 78% of those in group 2 remained in sinus rhythm. At the last follow-up, 88% of these patients in group 1 and 83% in group 2 remained in sinus rhythm. Among the patients in atrial fibrillation or junctional rhythm before operation, 12% in group 1 and 11% in group 2 had regained sinus rhythm at the last follow-up. There were no significant differences in these values.

Conclusions. Although the incidence of dysrhythmias was higher with the superior-septal approach in the early postoperative period, this approach provides an excellent operative view of the mitral valve and similar results in terms of late postoperative cardiac rhythms as the right lateral left atriotomy.

	Introduction

Top Footnotes Abstract Introduction Methods Results Comment Addendum References

 
One of the difficulties of mitral valve procedures is obtaining good exposure of the mitral valve because of its anatomic position. Various surgical approaches have been developed to solve this problem. In the last few years, many surgeons have become interested in the superior-septal approach because it provides excellent exposure of the mitral valve [1–7]. Recently, we have begun using this approach because of the increasing number of patients who require reoperation on or reconstruction of the mitral valve. Although the efficacy of this approach has been well accepted, its safety with respect to the preservation of cardiac rhythms remains controversial, as sinus node arteries are divided in most instances. In this study, we examined cardiac rhythms early and late postoperatively in patients who underwent mitral valve procedures and compared the results in patients having the superior-septal approach with those in patients having a conventional right lateral left atriotomy.

	Methods

Top Footnotes Abstract Introduction Methods Results Comment Addendum References

 
Data were collected on the 152 consecutive patients who underwent mitral valve operations between January 1992 and February 1995 at Kyushu University Hospital. Sixty-nine patients underwent a mitral valve procedure through a conventional right lateral left atriotomy (group 1) and 83 patients, through the superior-septal approach (group 2). All procedures were done during the same period by two different groups of surgeons. Selection of the approach was by surgeon preference. Only one surgeon performed mitral valve repair using artificial chordae.

The preoperative patient profiles of both groups were similar in terms of age, sex, New York Heart Association functional class, cardiothoracic ratio, physiology and pathology of the mitral valve, number of reoperations, and size of the left atrium as estimated by echocardiography (Table 1). The percentage of reoperations was high, and primary tissue failure of the bioprosthesis was the main reason. We had no instances of ischemic mitral valve disease.

In group 1, the right lateral left atriotomy was made behind and parallel to the interatrial groove. The incision was extended superiorly under the superior vena cava and inferiorly between the right inferior pulmonary vein and the inferior vena cava. Retractors were used to expose the mitral valve. The atriotomy was closed by two running 4-0 Prolene sutures (Ethicon, Somerville, NJ) starting from both ends of the incision. Right-sided procedures were performed through a separate right atrial incision after the aortic clamp was removed.

In group 2, the right atriotomy was performed parallel to the atrioventricular groove, and the incision was extended superiorly into the atrial appendage to meet the superior aspect of the interatrial septum. The left atrial incision was made in the fossa ovalis and extended superiorly to join the right atrial incision. From this point, the left atrial incision was extended onto the superior roof of the left atrium under the ascending aorta. The mitral valve was exposed with traction sutures. The superior wall of the left atrium and the atrial septum were closed with running 4-0 Prolene sutures. Right-sided procedures were performed during aortic cross-clamping by surgeon preference, and the right atrial wall was closed after removal of the aortic clamp. The differences in perfusion time and cross-clamp time were due mainly to the timing of the removal of the aortic clamp in each group and were not significant (Table 3).

For all patients, 12-lead electrocardiograms were made at admission, before discharge (10 days after operation), and at each follow-up visit including the last. We read electrocardiograms with a P wave as sinus rhythm because definition of morphologic change of the P wave is unclear. The difference in the P-wave axis before operation and at the last follow-up was calculated. Intraoperative transesophageal echocardiography and transthoracic echocardiography before discharge were done routinely. Preoperative coronary angiography was performed in 13 of the 19 patients in sinus rhythm preoperatively in group 2. Postoperative electrophysiologic study was performed in 2 patients in sinus rhythm preoperatively in group 2.

Analysis of differences between groups was done by unpaired Student's t test on continuous variable comparisons or by ² contingency tables on discrete variable comparisons. Multiple logistic regression analysis was performed to determine predictors of rhythm change. The statistical analysis was carried out using SPSS software (SPSS Inc, Chicago, IL) on a Macintosh 7500 computer, and p values of less than 0.05 were considered significant.

	Results

Top Footnotes Abstract Introduction Methods Results Comment Addendum References

 
One patient in atrial fibrillation preoperatively died in group 1 (operative mortality rate, 1.4%), and 1 patient in sinus rhythm preoperatively died in group 2 (operative mortality rate, 1.2%). The causes of death were not related to the left atriotomy. These 2 patients were excluded from the analysis of postoperative cardiac rhythms.

In 1 patient who underwent operation with the superior-septal approach, an equine pericardial patch was necessary to close the superior wall of the left atrium, which was severely calcified. No patient in either group was returned to the operating room because of bleeding from the left atriotomy. The average duration of postoperative hospitalization was 21.2 days in group 1 and 21.3 days in group 2, and the length of these hospitalizations was similar to that (21.6 days) of all our cardiac patients. Follow-up ranged from 2 to 38 months. The mean follow-up was 16.1 months in group 1 and 13.8 months in group 2, and the cumulative follow-up was 1,112 patient-months in group 1 and 1,142 patient-months in group 2.

During hospitalization, 8 patients in sinus rhythm preoperatively in group 1 experienced dysrhythmias (33%). Among them, 6 patients in transient atrial fibrillation and 1 patient in junctional rhythm had sinus rhythm restored during the hospital stay. Among the patients in sinus rhythm preoperatively in group 2, 10 patients had dysrhythmias (56%). Six of them had transient atrial fibrillation, which recovered to sinus rhythm during hospitalization, whereas dysrhythmias had persisted until discharge in the remaining 4 patients. Although the incidence of perioperative dysrhythmias was higher in group 2, the difference was not significant.

Among the patients in sinus rhythm preoperatively, the number in sinus rhythm at the time of discharge was higher in group 1 (96%) than in group 2 (78%), although not significantly so (Table 4). In group 1, only 1 patient had development of an arrhythmia (sick sinus syndrome). In group 2, atrial fibrillation developed in 2 patients and junctional rhythm in 1 patient, and another patient required pacemaker implantation for junctional bradycardia. Among the patients in atrial fibrillation or junctional rhythm preoperatively, 12% in group 1 and 5% in group 2 had regained sinus rhythm at the time of discharge.

Of the 19 patients in group 2 in sinus rhythm preoperatively, 13 underwent preoperative coronary angiography. A right sinus node artery was found in 7 patients and a left sinus node artery in 6. One patient with a right sinus node artery had development of atrial fibrillation after operation, whereas the others remained in sinus rhythm. There was no significant correlation between the distribution of the sinus node artery and the occurrence of postoperative rhythm disturbances.

Postoperative electrophysiologic study was performed 1 month after operation in 2 patients in sinus rhythm preoperatively in group 2. Their sinus node function as assessed by corrected sinus node recovery time was within the normal range; the sinoatrial time was extended in 1 patient, and the His bundle–ventricle time was extended in the other.

The analysis of predictors of postoperative dysrhythmias showed that reoperation was the only significant factor both at the time of discharge (p = 0.0037) and at the last follow-up (p = 0.0055). The superior-septal approach had a tendency to be a predictor at the time of discharge (p = 0.056) but not at the last follow-up (p = 0.9692). Duration of bypass and cross-clamping, associated disease, age, and sex were not significant predictors.

	Comment

Top Footnotes Abstract Introduction Methods Results Comment Addendum References

 
Because of its posterior location, exposure of the mitral valve is difficult, especially in patients with a small left atrium, a deep thoracic cavity, severe adhesions, severe calcification of the left atrial wall, or a combination of these. Various surgical approaches to the mitral valve, such as the conventional right lateral approach, the superior approach, the transseptal approach, and its modifications, for example, the DuBost approach, have been developed [8]. Combining the lateral approach and the superior approach is also a good alternative [9, 10], although it requires cumbersome temporary division of the superior vena cava. Recently, the superior-septal approach has become popular because it offers excellent exposure of the mitral valve and is easy to close. This approach has many names: combined superior-transseptal approach [1], extended vertical transatrial septal approach [2], extended vertical transseptal approach [3], septal-superior exposure [4], extended transseptal approach [5, 7], superior septal approach [6], and transplant approach [4]. Here we chose the term superior-septal approach according to the suggestion of Smith [11].

Despite the excellent view it affords, the superior-septal approach can damage the sinus node artery, which can result in postoperative sinus node dysfunction and dysrhythmias. The role of the sinus node artery in maintaining sinus rhythm is still controversial. Atrial arrhythmia after myocardial infarction with occlusion of the sinus node artery has been reported [12, 13], and Kyriakidis and co-workers [13] emphasized the important role of the sinus node artery in maintaining sinus rhythm. On the other hand, sinus node function of the recipient heart is maintained after transplantation even though the sinus node artery is completely resected [14]. Shin and associates [15] reported normal sinus node function postoperatively in 9 patients who underwent operation with the superior-septal approach and were evaluated by electrophysiologic study. In our series, 2 patients receiving treatment by the superior-septal approach and evaluated postoperatively by electrophysiologic study also showed normal sinus node function.

The reported incidence of postoperative dysrhythmias with the superior-septal approach varies. Berreklouw [2], Guiraudon [1], and their associates noted no dysrhythmias with this approach and emphasized its safety. Utley and colleagues [6] found that only 46% of patients who were in sinus rhythm preoperatively and had operation through the superior-septal approach remained in sinus rhythm versus 80% of patients operated on through the conventional right lateral approach and 69%, through the transseptal approach. Kon and co-workers [5] reported that 81% of patients in sinus rhythm preoperatively remained in sinus rhythm postoperatively and 22% of patients in atrial fibrillation preoperatively had sinus rhythm restored postoperatively. Their results were comparable to ours. However, most of these reports concern early postoperative results or have an unspecified length of follow-up.

Recently, Kumar and colleagues [7] reported a high incidence of transient junctional rhythm in the early postoperative period with the superior-septal approach compared with the conventional right lateral approach. Although postoperative dysrhythmias are encountered quite frequently in patients who undergo mitral procedures even with the conventional lateral approach, we agree that there is a high incidence of early postoperative dysrhythmias in patients having operation through the superior-septal approach. Elongation of conduction time, revealed by postoperative electrophysiologic study in our 2 patients, might be a possible cause of postoperative dysrhythmias, although these 2 patients remained in sinus rhythm postoperatively. At the last follow-up, postoperative rhythms after the mitral valve procedures were similar between the patients having the superior-septal approach and those having the conventional right lateral approach. Thus, we emphasize the possibility of restoration of sinus rhythm at late follow-up not only in the patients in sinus rhythm preoperatively but also in the patients in atrial fibrillation preoperatively, even when the superior-septal approach is used.

In our series, 3 patients in group 1 and 4 patients in group 2 who had been in sinus rhythm preoperatively had development of postoperative dysrhythmias. Four of these 7 patients had undergone reoperation. Although dysrhythmias tend to develop early in the postoperative stage when the superior-septal approach is used, reoperation was the only significant predictor of postoperative dysrhythmias. Moreover, all 7 patients had long histories (greater than 19 years) of mitral valve disease. It is well known that the long duration of overload of the left atrium in mitral valve disease leads to atrial arrhythmia. Regardless of the type of incision, more than 10% of the patients in our series had development of atrial arrhythmias at the last follow-up.

In conclusion, the superior-septal approach is useful for mitral procedures because it provides excellent exposure. The high incidence of early postoperative dysrhythmias is a reason for caution, although the incidence of postoperative rhythms at the late follow-up was similar to that seen with use of the conventional right lateral left atriotomy.

	Addendum

Top Footnotes Abstract Introduction Methods Results Comment Addendum References

 
After we submitted this report, 32 more patients underwent mitral procedures with the superior-septal approach. Preoperatively, 11 patients were in sinus rhythm, 19 were in atrial fibrillation, and 2 were in pacemaker rhythm. One patient in sinus rhythm preoperatively had development of atrial flutter at the last follow-up. The percentage remaining in sinus rhythm among the patients in sinus rhythm preoperatively and operated on using the superior-septal approach, including the patients in the study, was 86% at the time of discharge and last follow-up. One patient in atrial fibrillation preoperatively had sinus rhythm restored before discharge. We did not include these patients in the report because the superior-septal approach has become our approach of choice for mitral procedures since the submission of this study, and so there were no comparable data for the conventional lateral left atriotomy.

	Footnotes

Top Footnotes Abstract Introduction Methods Results Comment Addendum References

 
Address reprint requests to Dr Masuda, Department of Cardiovascular Surgery, Research Institute of Angiocardiology, Faculty of Medicine, Kyushu University, Maidashi 3-1-1, Higashi-ku, Fukuoka 812-82, Japan.

	References

Top Footnotes Abstract Introduction Methods Results Comment Addendum References

 

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3. Alfieri O, Sandrelli L, Pardini A, et al. Optimal exposure of the mitral valve through an extended vertical transseptal approach. Eur J Cardio-thorac Surg 1991;5:294–9.[Abstract]
4. Smith CR. Septal-superior exposure of the mitral valve. The transplant approach. J Thorac Cardiovasc Surg 1992;103:623–8.[Abstract]
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7. Kumar N, Saad E, Prabhakar G, De Vol E, Duran CMG. Extended transseptal versus conventional left atriotomy: early postoperative study. Ann Thorac Surg 1995;60:426–30.[Abstract/Free Full Text]
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This Article Abstract Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Munetaka Masuda Shigeki Morita Yukihiro Tomita Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Masuda, M. Articles by Yasui, H. Search for Related Content PubMed PubMed Citation Articles by Masuda, M. Articles by Yasui, H.