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Ann Thorac Surg 2003;75:1181-1184
© 2003 The Society of Thoracic Surgeons

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Original article: cardiovascular

Early and late arrhythmias in patients in preoperative sinus rhythm submitted to mitral valve surgery through the superior septal approach

^a Department of Cardiac Surgery, Catholic University, Rome, Italy

Accepted for publication October 18, 2002.

^* Address reprint requests to Dr Gaudino, Divisione di Cardiochirurgia, Policlinico Universitario A. Gemelli, Largo A. Gemelli 8, 00168 Rome, Italy
e-mail: mgaudino{at}tiscalinet.it

	Abstract

Top Abstract Introduction Patients and methods Results Comment References

 
BACKGROUND: It has been hypothesized that the use of the superior septal approach to the mitral valve can lead to postoperative loss of sinus rhythm. This study was undertaken to evaluate the early and mid-term alterations of the cardiac rhythm in patients with preoperative sinus rhythm (SR) submitted to mitral valve surgery through the superior septal approach

METHODS: Seventy-five cases in preoperative SR submitted to primary isolated mitral valve surgery through the superior septal approach constitute the study population. All patients underwent 12-lead electrocardiography on admission, every day after surgery until discharge and every year during the follow-up period.

RESULTS: On admission in the intensive care unit, 46 cases maintained their preoperative rhythm, whereas 18 developed a junctional rhythm (JR) and 7 had a first- or second-degree atrio-ventricular block (AVB). Four cases arrived in the unit in atrial fibrillation (AF). On the first postoperative day, these proportions were substantially unchanged, with the only exception being a slight increase in the number of patients in AF. The day before discharge, only 35 of the 74 surviving cases maintained the preoperative SR, whereas 13 developed AF, 10 were in JR, and 16 were in AVB. During the follow-up period (mean, 26 ± 14 months), the majority of cases (47/74) regained SR; 11 patients had AVB, 3 were in JR, and the remaining 13 were in AF.

CONCLUSIONS: The use of the superior septal approach for mitral valve procedures in patients in preoperative SR is associated with minor, transient cardiac rhythm disturbances.

	Introduction

Top Abstract Introduction Patients and methods Results Comment References

 
An adequate exposure of the valve and subvalvular apparatus is of great importance in mitral valve surgery, especially when performing valve repair or redo procedures. The traditional longitudinal left atrial approach, which has been used for decades, may not provide optimal visualization in some instances (such as in patients with a deep chest or a small left atrium). Among the various alternative atrial approaches proposed, the superior septal approach (SSA), originally described by Guiraudon and associates [1], allows adequate exposure in almost all anatomic conditions. However, this approach implies division of the sinus node artery and part of the internodal pathways, and controversy still exists on the safety of SSA in terms of postoperative cardiac rhythm disturbances [2, 3]. Obviously, concerns for postoperative dysrhythmias are particularly relevant in patients with preoperative sinus rhythm (SR).

In a previous study, we showed how in the general population of patients submitted to mitral valve surgery, the use of SSA is not associated with an increased incidence of arrhythmias either in-hospital and during the mid-term follow-up period [4].

In this report, we focus on patients in preoperative SR and describe the early and mid-term modifications of cardiac rhythm in a series of 75 consecutive mitral valve patients in preoperative SR submitted to isolated mitral valve surgery through the SSA.

	Patients and methods

Top Abstract Introduction Patients and methods Results Comment References

 
Patient population
Since the completion of our previous randomized study on the comparison between SSA and conventional left atrial incision in 1996 [4], the SSA has become the standard approach for all mitral valve procedures at our institution.

The study population of the present report is composed of all cases submitted to primary isolated mitral valve surgery between January 1998 and December 2000 who were in preoperative sinus rhythm (SR). Preoperative rhythm different from SR (including SR with atrio-ventricular block), associated procedures (either valvular or coronary), and reoperations were all excluded. With these criteria, we enrolled a total of 75 cases. The main pre- and intraoperative features of these 75 patients are summarized in Table 1.

Follow-up
All patients underwent a 12-lead electrocardiography on admission, every postoperative day until discharge, and in case of clinical suspicion of arrhythmia. The cardiac rhythm of all cases was continuously monitored during their stay in the intensive care unit. Twenty-four-hour Holter examination or electrophysiological testing was performed in cases of complex dysrythmias only.

No preoperative pharmacological treatment for the prevention of atrial arrhythmias was used. In case of development of postoperative dysrythmias, pharmacological treatment with amiodarone, systemic anticoagulation with heparin, and external ventricular pacing at 50 bpm (for the prevention of bradyarrhythmic episodes) were immediately started. External electric cardioversion was considered necessary only in those patients in whom the atrial arrhythmia was associated with an unstable hemodynamic or with potentially dangerous dysrythmias.

Intraoperative transesophageal echocardiography was used in all cases. All patients were submitted to transthoracic echocardiography preoperatively, on the first postoperative day, and before discharge.

Each patient was then followed up regularly at our institution by clinical examination, 12-lead electrocardiogram, 24-hour Holter monitoring, and transthoracic echocardiography at 6 months after surgery and every year thereafter. For the purpose of the present study, all patients were recalled and all exams repeated at the time of the collection of follow-up data. Follow-up was 100% complete (74/74 surviving patients), and the mean follow-up time was 26 ± 14 months.

Statistical analysis
The ² test was used to compare discrete parameters. Continuous variables (expressed as means ± SD) were compared by parametric (or nonparametric, when data remained skewed) tests.

To identify potential predictors of the development of late postoperative atrial fibrillation (AF), patients were divided in two groups on the basis of cardiac rhythm shown at the time of follow up: cases who developed AF (AF group) versus patients who had non-AF rhythms (sinus rhythm, junctional rhythm, atrio-ventricular block of first and second degree) (non-AF group). Relationships among various clinical and instrumental pre-, intra-, and postoperative parameters (age, gender, cardiac index, ejection fraction, echocardiographic atrial and ventricular dimensions, tricuspidal insufficiency, cross-clamp time, cardiopulmonary bypass time, and intensive care unit and in-hospital stays), and the development of late AFs were then assessed by using Spearman’s and when possible a parametric correlation test (student’s t test). Analyses were carried out using the SAS statistical package, version 8.1 (SAS Institute, Cary, NC). Statistical significance was defined by a two-tailed p < 0.05.

	Results

Top Abstract Introduction Patients and methods Results Comment References

 
Mortality and morbidity
Main intra- and postoperative results are reported in Tables 2 and 3. Summarizing, there was one in-hospital death for perioperative stroke (1.3%), 4 patients developed transient postoperative renal insufficiency (1 requiring dialysis), and 1 patient had a perioperative stroke. No case of residual atrial septal defect from the use of the SSA was reported.

Early and late modifications of cardiac rhythm are summarized in Figure 1. At arrival in the intensive care unit, 46 of the 75 cases maintained their preoperative rhythm (61.3%), whereas 18 (24%) developed a junctional rhythm (JR) and 7 (9.3%) had a first- or second-degree atrio-ventricular block (AVB). Four cases (5.3%) arrived in the unit in atrial fibrillation. At the first postoperative day, these proportions were substantially unchanged, with the only exception being a slight increase in the number of patients in AF. The day before discharge, only 35 of the 74 surviving patients maintained the preoperative SR (47.2%), whereas 13 developed AF (17.5%), 10 were in JR (13.5%), and 16 were in AVB (21.6%). Overall, only 31 of the 75 cases (41.3%) were discharged from the hospital without any modification (at least transient) of their preoperative rhythm. In-hospital, no patient required implantation of a definitive pacemaker or electric defibrillation, and in all cases, pharmacological treatment and external pacing were able to assure an acceptable hemodynamic and rhythm status.

View larger version (22K): [in this window] [in a new window]   Fig 1. Early and mid-term rhythm modifications. Open bars = atrial fibrillation; hatched bars = junctional rhythm; black bars = atrioventricular block; filled bars = sinus rhythm. (ICU = intensive care unit; n = number; I Post-op. = first postoperative; Preop. = preoperative.)

Statistical analysis showed that the AF group consisted of older patients (p = 0.004), with a lower preoperative cardiac index (p = 0.01), a larger tele-diastolic left ventricular volume (p = 0.002), and a longer cardiopulmonary bypass time (p = 0.003). Atrial fibrillation (AF) patients had also a trend towards a larger left atrial volume (p = 0.11), a lower ejection fraction, an increased tele-systolic left ventricular volume, and a longer intensive care unit stay, even if these last differences were not statistically significant (p < 0.1).

	Comment

Top Abstract Introduction Patients and methods Results Comment References

 
An adequate exposure is essential in mitral valve surgery and, in particular, in cases of reparative procedures or reoperations. Although the traditional longitudinal left atrial incision has been in use for decades, all surgeons familiar with it would agree that this approach may not provide optimal visualization in some cases (particularly in those patients with deep chest, small left atrium, and in redo operations). The SSA was proposed to overcome this limitation. In fact, it assures a good exposure of the operative field in almost every anatomic condition. However, this approach implies the need to transect the sinus node artery and part of the internodal pathways. Although anatomic and clinical data on the effect of the lesion of these structures on cardiac rhythm are discordant [5–7], some authors have raised the possibility that the use of the SSA can lead to postoperative arrhythmias and have advocated caution in its use [2, 3].

In fact, Kovacs and Szabados [8] and Smith and associates [9] in 1994, and Kumar and colleagues [10] in the following year, described an increased incidence of postoperative rhythm disturbances in mitral valve patients operated on through the SSA [8–10], and Bernstein and coauthors in 1996 reported an unacceptably high incidence of loss of preoperative SR in a small group of 22 SSA cases [3].

On the other hand, other authors reported more favorable results. Berreklouw and associates [11], in their series of 22 cases operated on through the SSA, noted maintenance of rhythm in all patients in preoperative SR, and Alfieri and colleagues [12] and Kon and coauthors [13] reported no major postoperative rhythm disturbances in larger studies of patients who underwent mitral valve procedures using SSA. More recently, Masuda and colleagues [14] described how SSA can be associated with an increased incidence of early, but not late, cardiac dysrhythmias, and our group showed in a large prospective randomized investigation that the use of SSA is not associated with an increased incidence of clinical rhythm disturbances either in-hospital and during the mid-term follow-up period [4]. Even electrophysiological studies denied long-term adverse effects on sinus node function and conduction of SSA [15, 16].

However, all the published series described the results achieved in the general population of patients submitted to mitral valve surgery, independently from the preoperative cardiac rhythm. Mitral patients in preoperative SR constitute a group of great interest with regard to the use of the SSA because they usually have a smaller left atrium (and thus can constitute a subgroup of patients for whom the traditional left atrial incision is unable to assure an adequate visualization of the mitral apparatus). In the meantime, these cases are those who would pay the highest price in case of incision-related postoperative rhythm disturbances.

The present report is the first to describe the early and mid-term rhythm outcome of a large consecutive series of patients in preoperative SR submitted to isolated mitral valve surgery through the SSA, providing the first nonanecdotal evidence of how the use of this approach can influence cardiac rhythm both in-hospital and in the years after surgery.

In the early postoperative period, maintenance of a stable SR was quite low, with only 31 of the 75 cases discharged from the hospital without modification (at least transient) of their preoperative rhythm; however, the great majority of the cases who lost the SR developed a stable JR or were in SR with first- or (only in one case) second-degree AVB, and in no case, were dysrhythmias clinically concerning or required definitive pacemaker implantation.

During the follow-up period, a substantial proportion of patients who left the hospital in AVB or JR regained their SR. Three years after surgery, 47 cases were in stable SR, 11 had SR with first-degree AVB, 3 remained in JR, and 13 were in AF.

In our series, the incidence of both early and late development of AF is similar (or even lower) to that reported in patients in preoperative SR submitted to mitral valve replacement through the conventional left atrial approach, whereas the early (but not late) occurrence of AVB or JR seems somehow increased [4, 17–19] (although comparison with the published literature has a doubtful methodological validity).

It seems that the use of SSA in patients in preoperative SR can be associated with transient early rhythm disturbances, in particular AVB and JR, whereas not increasing the risk of postoperative AF. This is probably explained by surgical trauma to the sinus node artery and (more importantly) to the internodal pathways. However, during the mid-term follow-up period, a large part of the cases in JR or AVB regained SR, testifying to the transient nature of the damage to the cardiac conduction system.

Furthermore, in our series, the use of SSA was not associated with clinically relevant rhythm disturbances both in-hospital and during the follow-up period.

In conclusion, this study shows how, even in cases in preoperative SR, concerns for clinically relevant rhythm disturbances from the use of SSA at the time of surgery are not justified. The SSA continues to be a valid alternative to the traditional left atrial incision for mitral valve procedures.

	References

Top Abstract Introduction Patients and methods Results Comment References

 

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This Article Abstract Full Text (PDF) 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): Mario Gaudino Andrea Salica Nicola Luciani Mauro Morelli Gianfederico Possati Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Gaudino, M. Articles by Possati, G. Search for Related Content PubMed PubMed Citation Articles by Gaudino, M. Articles by Possati, G. Related Collections Valve disease