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Ann Thorac Surg 2005;79:1276-1283
© 2005 The Society of Thoracic Surgeons
Cardiovascular Surgeons, PA, Florida Hospital Cardiovascular Institute, Orlando, Florida
Accepted for publication September 21, 2004.
* Address reprint requests to Dr Accola, Cardiovascular Surgeons, PA, 217 Hillcrest St, Orlando, FL 32801 (E-mail: kaccola{at}aol.com).
Presented at the Fiftieth Annual Meeting of the Southern Thoracic Surgical Association, Bonita Springs, FL, Nov 13–15, 2003.
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Abstract |
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 Top Abstract IntroductionPatients and MethodsResultsCommentDISCUSSIONAcknowledgmentsReferences |
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METHODS: Between April 1994 and October 2000, 492 consecutive patients underwent mitral valve reconstruction using standardized Carpentier techniques with the Carpentier-Edwards Physio Ring (Edwards Lifesciences LLC, Irvine, CA). There were 267 men (54.3%) and 225 women (45.7%). Mean age was 64.2 years (range, 18 to 86). Almost one-half (44.3%) were 70 years of age or over. The mitral valve etiology was congenital in 7 patients (1.4%), myxomatous in 351 patients (71.3%), ischemic in 88 (17.9%), rheumatic in 26 (5.3%), endocarditis in 9 (1.8%), calcific in 8 (1.6%), and other abnormalities in 3 (0.6%).
RESULTS: Isolated mitral valve reconstruction was performed in 282 patients (57.3%), with coronary artery bypass grafting (CABG) in 182 (37.0%), with valve replacement in 11 (2.2%), and with CABG and valve replacement in 17 (3.5%). All patients (100.0%) had ring annuloplasty, 263 (53.5%) leaflet resection, 140 (28.5%) chordal resection, 55 (11.2%) chordal transposition, 48 (9.8%) chordal shortening, and 15 (3.0%) commissurotomy. Overall hospital mortality was 3.5% (17 of 492). Postoperative complications included respiratory insufficiency in 55 patients (11.2%), low cardiac output in 13 (2.6%), stroke in 14 (2.8%), reoperation for bleeding in 13 (2.6%), renal insufficiency in 21 (4.3%), and myocardial infarction in 5 (1.0%), and new onset of atrial fibrillation in 74 patients (15.0%). The cumulative follow-up for the series was 1,522.9 patient years and ranged from 1 to 101.0 months (mean, 38.5 months). There were 11 reconstruction failures (2.3%) requiring ring explant. Actuarial survival was 81.5% ± 2.1% at 4 years and 67.9% ± 4.6% at 7 years. Freedom from reoperation at 4 years was 81.5% ± 2.1% and 67.9% ± 4.6% at 7 years.
CONCLUSIONS: Mitral valve reconstruction with the Physio Ring can be accomplished with low hospital mortality and morbidity even in combined procedures. Moreover, the low incidence of reoperation and late cardiac events suggests that the Physio Ring, with its inherent flexibility, offers a definite advantage in the application of remodeling techniques in mitral valve reconstruction.
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Introduction |
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TopAbstractIntroductionPatients and MethodsResultsCommentDISCUSSIONAcknowledgmentsReferences |
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Since first introduced [1–5] the evolution of mitral valve reconstruction techniques have flourished. The work of Carpentier and colleagues [6–8] and Duran and colleagues [9–11] has established and demonstrated surgical techniques that are standardized, reproducible, and over time have provided excellent long-term clinical results. Mitral valve reconstruction is associated with low operative mortality and morbidity [12], improved left ventricular function in the immediate postoperative period [13], and enhanced long-term survival [14]. The application of reconstructive techniques in various cohorts of patients (those with rheumatic disease [15], flail leaflet [16], cardiomyopathy [17], the elderly [18], etc) have also demonstrated excellent results. Moreover, ischemic mitral insufficiency, now better understood as a left ventricular or papillary muscle dysfunction, has been shown functionally to be treated effectively with reduction annuloplasty. A "physiologic" annuloplasty ring offers an advantage in these patients by maintaining the fluidlike dynamic function of the annulus. These factors make reconstructive surgery the procedure of choice for the treatment of a vast majority of patients with mitral valve disease.
The purpose of this retrospective study is to discern the efficacy and clinical performance of the Physio Ring as an advanced concept in mitral valve reconstruction [19]. Moreover, it focuses on assessing the durability of valve reconstruction, patient symptomatic improvement, and patient functional outcomes.
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Patients and Methods |
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TopAbstractIntroductionPatients and MethodsResultsCommentDISCUSSIONAcknowledgmentsReferences |
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The patient’s preoperative functional status was ranked according to the New York Heart Association (NYHA) classification system. Thirty-five patients (7.1%) were in class I, 212 patients (43.1%) in class II, 171 patients (34.8%) in class III, and 74 patients (15.0%) in class IV. In addition, the patient’s preoperative angina status was rated according to the Canadian Cardiovascular Society classification system. Thirty patients (6.1%) were in class 0 (no angina), 51 patients (10.4%) were in class I, 202 patients (41.1%) in class II, 151 patients (30.7%) in class III, and 58 patients (11.8%) in class IV. The clinical characteristics of the patient population are summarized in Table 1.
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Definitions
PREOPERATIVE VARIABLES
Pulmonary hypertension was defined as systolic pulmonary artery pressure greater than 60 mm Hg or pulmonary vascular resistance greater than 260 dynes · sec · cm – 5. Congestive heart failure was defined as paroxysmal nocturnal dyspnea, dyspnea on exertion due to heart failure, or chest roentgenogram showing pulmonary congestion.
Elective surgery was defined as an operation, which could be deferred without increased risk of compromised cardiac outcome. An urgent operation was defined as being required within 48 hours in an effort to prevent further clinical deterioration. An emergency operation was defined as those instances where the patient did not respond to aggressive clinical measures and clinical decompensation continued to occur. A salvage operation was defined as those in which the patient was undergoing cardiopulmonary resuscitation in route to the operating room, before anesthesia induction, or in cardiogenic shock.
POSTOPERATIVE VARIABLES
Respiratory insufficiency was defined as patients requiring ventilatory support for greater than 48 hours. Cerebrovascular accident was defined as a focal neurologic deficit that remained unresolved and persisted for greater than 24 hours. Perioperative myocardial infarction was defined as the occurrence of a new onset of Q waves, with or without increased myocardial enzyme levels. Renal insufficiency was defined as a creatinine level greater than or equal to 2.0 mg/dL. Low cardiac output referred to clinical evidence of hypotension, oliguria, and peripheral vascular constriction with normal or supranormal left ventricular filling pressure or a measured cardiac index of less than 2L · min–1 · m–2, necessitating the administration of catecholamines or the use of the intraaortic balloon pump, or both. Hospital mortality was defined as death occurring during the operation or the hospitalization in which the procedure was performed, or death occurring after discharge from the hospital but within 30 days of the surgical procedure, unless the cause was clearly unrelated to the operation.
Operative Technique
Median sternotomy was utilized for a majority of cases; however, a right thoracotomy approach was used in selected cases. Echocardiography has provided for more accurate assessment preoperatively of pathologic valve anatomy and improved intraoperative assessment of the reconstructed value. Transesophageal echocardiography was performed in all cases intraoperatively and early postreconstruction to assess valve function.
Standard cannulation and myocardial preservation techniques were utilized with cardiopulmonary bypass and moderate hypothermia. Concomitant coronary revascularization, if required, was performed after initially instituting bypass and before the application of valve reconstruction techniques. Assessment of the mitral valve was accomplished utilizing Carpentier’s methods of valve analysis [8].
Prosthetic ring annuloplasty was performed in all cases to reinforce the reconstruction, to enhance its durability, and for its remodeling effect. The annuloplasty reduces the area that the leaflets must cover and allows for appropriate leaflet coaptation. The Physio Ring, with its inherent flexibility, allows for the necessary changes in shape required during the cardiac cycle.
Simple type I annular remodeling was performed with reduction of the annulus, which was typically downsized one to two sizes. Standardized horizontal mattress sutures were placed circumferentially to secure the annuloplasty ring. In more complex type II and III reconstructions, involving increased valve abnormality, judicious use of concomitant posterior chordal elongation-resection, posterior leaflet sliding valvuloplasty, and leaflet resection techniques were incorporated in the valve reconstruction. Quadrangular resection was performed at the base of the posterior leaflet remnants to correct excessive tissue. Interrupted or figure eight 4-0 and 5-0 polypropylene sutures were utilized when performing posterior leaflet reconstruction. Anterior leaflet pathology was addressed using chordal transfer techniques or Gore-Tex suture chordal replacement (W L Gore & Assoc, Flagstaff, AZ).
The mean cardiopulmonary bypass time for isolated mitral valve reconstruction was 80.2 ± 27.9 minutes (range, 38 to 234 minutes) and 127.4 ± 44.1 minutes (range, 52 to 274 minutes) for combined procedures (p = 0.001). The mean aortic cross-clamping time for isolated mitral valve was 63.1 ± 20.8 minutes (range, 25 to 193 minutes) and 93.9 ± 31.4 minutes (range, 30 to 192 minutes) for combined procedures (p = 0.001).
Operative Data
The operation was performed electively in 439 patients (89.2%), urgently in 41 patients (8.3%), emergently in 8 patients (1.6%), and as salvage in 4 patients (0.8%). The mitral valve dysfunction was pure insufficiency in 483 patients (98.2%) and mixed disease, stenosis, and insufficiency, in 9 patients (1.8%). In 201 patients (40.9%) the degree of insufficiency was 3+ and in 291 patients (59.1%) it was 4+. The etiology of the mitral valve disease was congenital in 7 patients (1.4%), myxomatous degeneration in 351 patients (71.3%), associated ischemic in 88 patients (17.9%), rheumatic in 26 patients (5.3%), endocarditis in 9 patients (1.8%), calcific in 8 patients (1.6%), and other abnormalities in 3 patients (0.6%).
Physiopathology of the valve lesion based on Carpentier’s functional classification system was the following: type I, normal leaflet motion, dilated annulus, or leaflet perforation in 128 patients (26.0%); type II, leaflet prolapse, chordal rupture, chordal elongation, papillary muscle rupture, or papillary muscle elongation in 183 patients (37.2%); and type III, restricted leaflet motion, commissure fusion, leaflet thickening, or chordal fusion-thickening in 28 patients (5.7%). One hundred forty-one patients (28.7%) were classified as type I/II and 12 patients (2.4%) as type II/III. Leaflet involvement was normal in 72 patients (14.6%), anterior only in 52 patients (10.6%), anterior and posterior in 74 patients (15.0%), and posterior only in 294 patients (59.8%).
Mitral valve reconstruction techniques used included: commissurotomy in 15 patients (3.0%), chordal shortening in 48 patients (9.8%), chordal transposition in 55 patients (11.2%), chordal resection in 140 patients (28.5%), and leaflet resection in 263 patients (53.5%). All patients (100.0%) in the study underwent mitral valve ring annuloplasty with the Physio Ring. Concomitant cardiac procedures performed in the series included coronary artery bypass grafting (CABG) in 182 patients (37.0%), aortic valve replacement in 11 patients (2.2%), and CABG with valve replacement in 17 patients (3.5%). Echocardiography was performed preoperatively and intraoperatively after mitral valve reconstruction. The pattern of change and the degree of mitral insufficiency prevalve and postvalve reconstruction is shown in Figure 1.
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A Patient Registration Form and a Patient Follow-Up Form were completed for each participant in the study. These data collection instruments provided standardized reporting of each patient’s clinical status before and after the operation. A 96.7% follow-up was obtained in the present study (n = 492) with 16 patients lost to follow-up.
Statistical Analysis
Data are presented as frequency distributions and simple percentages. Values of continuous variables are expressed as mean ± standard deviation. Univariate analysis of selected discrete variables was accomplished by 
2, the continuity-adjusted 2 analysis, or a two-tailed Fisher’s exact test with the appropriate degrees of freedom to test for the equality of proportions in the case of categorical variables.
Patient survival was expressed by actuarial analysis according to the method of Cutler and Ederer [20] using time zero as the date of operation and late death as the endpoint (with variability expressed as the standard error of the mean) and by linearized occurrence rates with standard errors. Data collected were subjected to both quantitative and qualitative analysis using the biostatistical capabilities of the Patient Analysis and Tracking Systems (PATS; Axis Clinical Software, Inc, Portland, OR) and the Number Cruncher Statistical System (NCSS; Kaysville, UT). A significant difference between measurements was defined as p less than or equal to 0.05.
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Results |
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TopAbstractIntroductionPatients and MethodsResultsCommentDISCUSSIONAcknowledgmentsReferences |
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Placement of the intraaortic balloon pump was required in 54 patients (11.0%), 38 (7.7%) of whom had it placed preoperatively, 14 patients (2.8%) intraoperatively, and 2 patients (0.4%) postoperatively. The need for intraaortic balloon placement preoperatively (n = 38) was low cardiac output in 9 patients (1.8%), unstable angina in 1 patient (0.2%), shock in 3 patients (0.6%), prophylactic in 23 patients (4.7%), and other in 2 patients (0.4%). The indications for intraaortic balloon intraoperatively (n = 14) was low cardiac output in 4 patients (0.8%), cardiopulmonary bypass wean in 9 patients (1.8%), and shock in 1 patient (0.2%). The intraaortic balloon was placed postoperatively (n = 2) for low cardiac output in 1 patient (0.2%) and shock in 1 patient (0.2%). None of the patients requiring the intraaortic balloon pump experienced a major vascular complication. The average postoperative length of stay in the series was 9.2 ± 6.0 days.
Hospital Mortality Rate
The hospital mortality rate for isolated mitral valve reconstruction was 2.1% (6 of 282); for valve reconstruction and CABG, 4.9% (9 of 182); for valve reconstruction and aortic valve replacement, 9.1% (1 of 11); and for valve reconstruction, aortic valve replacement, and CABG, 5.9% (1 of 17). A comparison of the isolated valve reconstruction and combined procedure hospital mortality rates was found to be nonsignificant.
The overall hospital mortality rate for the series was 3.5% (17 of 492). The elective mortality rate was 2.5% (11 of 439), the urgent mortality rate 9.8% (4 of 41), the emergent mortality rate 12.5% (1 of 8), and the salvage mortality rate 25.0% (1 of 4). Comparisons of the mortality rates for elective and nonelective operation was found to be statistically significant (p = 0.003). The mortality rate for first operation was 3.2% (15 of 462) and 6.7% (2 of 30) for reoperation. This difference did not achieve statistical significance.
Patient Follow-Up
Follow-up data were collected for 475 patients (96.5%) discharged from the hospital. The follow-up ranged from 1 month to 101.0 months (mean, 38.5 months). The cumulative follow-up for the series was 1,522.9 patient-years. The linearized late mortality rate was 4.40% ± 0.54% per patient-year (67 events). At the completion of the follow-up, 392 (83.5%) of the hospital survivors were alive. Information concerning the causes of late death and the number of patients lost to follow-up is presented in Table 2. The actuarial survival data for all patients in the series are shown in Figure 2. At 4 years, survival was 81.5 ± 2.1% standard error of the mean (SEM), and at 7 years was 67.9% ± 4.6% SEM. The preoperative and postoperative NYHA classification of current survivors (n = 392) and their patterns of change are shown in Figure 3. Preoperatively, 45.6% of the patients were in either NYHA class III or IV; on completion of the current follow-up, 97.4% were in class I or II. These results are impressive and demonstrate an overall enhanced symptomatic and functional improvement in this cohort of patients.
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There were 11 valve reconstruction failures in the series occurring at various time intervals and for varying causes (Table 3). In 10 cases, the valve was replaced and in one case reconstruction was performed again using a Carpentier-Edwards Classic ring. The actuarial freedom from reoperation (Physio Ring explant) or death for the series is shown in Figure 4. The freedom from reoperation at 4 years was 81.5% ± 2.1% and 67.9% ± 4.6% at 7 years. The linearized occurrence rate and number of late cardiac events in the hospital survivors were as follows: nonfatal myocardial infarction, 0.26% ± 0.13% per patient-year (4 events); reoperation, 0.72% ± 0.22% per patient-year (11 events); and stroke, 0.33% ± 0.15% per patient-year (5 events). Late nonfatal myocardial infarction was diagnosed and documented by a standardized reporting method that included a review of the patient’s hospital records, physician’s records, or the patient’s medical history.
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Comment |
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TopAbstractIntroductionPatients and MethodsResultsCommentDISCUSSIONAcknowledgmentsReferences |
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Prosthetic ring annuloplasty and the application of concomitant valve reconstruction techniques is now the treatment of choice for patients presenting with mitral insufficiency. The stabilizing effect of ring annuloplasty has contributed significantly to the excellent long-term clinical results achieved in mitral reconstruction and in patients presenting with ischemic valve disease.
Standardized techniques as described by Carpentier and used since the decades of the 1970s have shown their reproducibility [8] and have demonstrated excellent outcomes over time [13]. The early and long-term results of mitral valve reconstruction have yielded better outcomes than those achieved with valve replacement. Moreover, the application of reparative techniques reduces or eliminates the need for long-term anticoagulation and its attendant risks.
Controversy continues to exist as to the "appropriate" annuloplasty ring for mitral valve reconstruction. Our choice of the Physio Ring, a flexible device, is based on a series of considerations. The dynamic relationship between the annulus and the subvalvular apparatus raises a series of questions concerning the application of rigid annuloplasty fixation. The use of a rigid ring may induce systolic anterior motion and left ventricular outflow tract obstruction [21] which may, in turn, cause postoperative left ventricular dysfunction [12]. Moreover, a rigid annuloplasty ring has been noted to impair left ventricular systolic function [22] and may cause subvalvular stenosis [23].
The benefits of flexible versus rigid rings in left ventricular pump function have been previously reported [12]. It has been demonstrated that flexible rings follow the physiologic movement of the mitral annulus and interfere less with pump function. Flexible rings interfere less with valve motion, improve peak velocity, enhance left ventricular fractional shortening, and improve end-diastolic diameter and volume.
The Physio Ring furnishes not only variable flexibility but allows for remodeling of the annulus. It provides for remodeling by the presence of "rigid fixation" between the two commissures. This allows for restoration of the physiologic shape of the mitral annulus including its posterior aspect [19].
The Physio Ring, with its inherent variable flexibility, offers a definite advancement in the application of remodeling techniques in mitral valve reconstruction. It affords the opportunity for the application of remodeling techniques by the presence of a given degree of rigidity between the commissures. This allows for restoration of the physiologic shape of the mitral annulus including its posterior aspects. Moreover, it provides substantial benefits in the remodeling process and appears to be a more physiologically appropriate choice in mitral valve reconstruction. Valve classification and reconstruction have become universally standardized utilizing Carpentier’s techniques. Moreover, surgeons have achieved an understanding of the fluidlike dynamic function of the mitral annulus, which has further influenced the development of reparative techniques [12].
It is now recognized that in circumstances of ischemic mitral insufficiency type I and type IIIb (tethered posterior and anterior leaflet with annular dilatation) are generally attributed to left ventricular dysfunction and dilatation of the annulus generally attributed to ischemic cardiomyopathy. In these cases, simple annular reduction annuloplasty is typically sufficient to correct the problem of mitral insufficiency. In cases where decreasing annular size is required, the benefits of a "complete" ring are well recognized. A more "physiologic" or dynamic ring as opposed to the "fixed" or "rigid" ring has been shown to achieve enhanced results and improved postoperative ventricular function in these circumstances [19].
Complex type II classification reconstruction is best supported with an appropriately sized Physio Ring using classic trigone to trigone and anterior leaflet sizing techniques. The evidence of pliable and dynamic posterior annulus benefits may serve to enhance left ventricular function as well as the longevity of the reconstructed valve [12]. The Carpentier standard rigid Ring continues to be the device of choice in patients presenting with Barlow’s disease. The advantage of this device in patients with this pathology is that the anterior-posterior dimension of the anterior leaflet can be expanded, thus allowing the surgeon to "open" the ring to accommodate performing a complex reconstruction.
In valves presenting with type III physiopathology, it is often difficult to perform reconstruction and achieve the desired long-term benefits. Often these valves have an abnormal or thickened subvalvular apparatus, which generally is progressive in nature. This finding has often influenced us to proceed with mitral valve replacement rather than reconstruction in these patients.
In the present series, an overall operative mortality rate of 3.5% was observed. This compares favorably with that of other series of mitral valve reconstruction [24, 25]. Moreover the operative mortality was low; 2.1% for isolated valve reconstruction and 4.9% for mitral reconstruction and CABG. Follow-up data were obtained for 475 hospital survivors. At the completion of the current follow-up, there were 392 patients (83.5%) alive. The actuarial survival for patients discharged from the hospital at 4 years was 84.3% ± 2.1% and was 70.1% ± 4.6% at 7 years.
In the present study, symptomatic improvement was 97.4% of the patients in NYHA class I or II at last follow-up. Moreover, the patients functional capacity has been improved thereby enhancing their ability to carry out their activities of daily living and their overall quality of life.
Valve reconstruction failure in our experience has generally been a rare event. In the present study 11 patients (2.2%) required reoperation. An analysis of the etiology of the valve disease and the physiopathological classification revealed no causative pattern for the failures. The freedom from reoperation at 4 years was 81.5% ± 2.1% and 67.9% ± 4.6% at 7 years. Moreover, no case of atrial ventricular groove disruption or systolic anterior motion causing left ventricle outflow track obstruction was observed in the present series.
These midterm results using the Physio Ring provide substantial evidence that mitral valve reconstruction can be accomplished with low hospital morbidity and mortality rates even in patients undergoing combined procedures. The low incidence of reoperation and late cardiac events suggests that the Physio Ring, with its inherent flexibility, offers a definite advantage in the application of remodeling techniques and may positively influence long-term results. These findings support the continued use of the Physio Ring in patients presenting with mitral insufficiency secondary to degenerative disease of the mitral valve as well as in the clinical setting of ischemic mitral insufficiency. The Physio Ring can play a critical role in the operative management of patients presenting with mitral valve disease.
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DISCUSSION |
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TopAbstractIntroductionPatients and MethodsResultsCommentDISCUSSIONAcknowledgmentsReferences |
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DR ACCOLA: I appreciate your question. We anticoagulate all of our mitral valve repairs still. We don’t necessarily do it for three months but anywhere from six to eight weeks, for a couple of reasons: one, because a lot of these repairs are complex repairs with a lot of suture lines; the other reason is simply, too, because these patients, a lot of them, either had preoperative atrial fibrillation or experienced postoperative fibrillation. In our current environment where we practice, the majority of cardiologists also feel it is important to anticoagulate these patients for a temporary period of time.
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Acknowledgments |
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TopAbstractIntroductionPatients and MethodsResultsCommentDISCUSSIONAcknowledgmentsReferences |
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TopAbstractIntroductionPatients and MethodsResultsCommentDISCUSSIONAcknowledgmentsReferences |
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