D’Alfonso, Alessandro MD, PhD; Capestro, Filippo MD; Zingaro, Carlo MD; Matteucci, Sacha MD; Rescigno, Giuseppe MD; Torracca, Lucia MD
The first successful mitral valve (MV) surgery, a commissurotomy, was performed through a left thoracotomy in 1948 by Dr Charles P. Bailey.1 Later, the heart-lung machine facilitated the widespread application of MV surgery and allowed accurate mitral repair for degenerative disease especially approached through median sternotomy. Only during the 90s, because of new advances in technology and instrumentation, the concept of minimally invasive or less invasive surgery started to be applied to a variety of complex heart operations, such as MV repair (MVR), to reduce hospitalization, pain, and scar blemish. This evidence is structured in more than 4300 peer-reviewed articles.
Presently, minimally invasive MVR (MIMVR) is shifting from being a novel option for a minority of patients in a few centers to the mainstream, with excellent short- and long-term results that are comparable to those achieved with traditional sternotomy.2,3
However, the widespread application of this technique initially had been hampered by the steep learning curve and concerns regarding surgical safety. Many surgeons are worried to use MIMVR because of the reduced maneuverability and poor visibility that could jeopardize the postoperative surgical results.
This report analyzes a single surgeon’s results during a 10-year period with MIMVR via a right minithoracotomy, peripheral cannulation, external aortic cross-clamping, and MVR under direct vision.
MATERIALS AND METHODS
Patient Profile and Study Design
Between December 1999 and December 2010, 200 patients underwent MIMVR in two different hospitals: 172 (86.0%) patients received MIMVR between December 1999 and October 2008 at the Department of Cardiac Surgery, San Raffaele University Hospital in Milan, Italy, and 28 (14.0%) patients received MIMVR between November 2008 and December 2010 at the Department of Cardiac Surgery, Ancona Hospital, Italy. All procedures were performed by a single surgeon (L.T.).
Among these patients, 170 patients were diagnosed as having degenerative MR and nine as having endocarditis, and all of them received MVR and form the focus of the current study. The MIMVR patients who were operated on during the same period but diagnosed with mitral rheumatic disease (21 patients) were not included.
Patients with previous right thoracotomy, chest wall radiation, obesity, chronic obstructive pulmonary disease, significant pulmonary hypertension, and moderate aortic regurgitation were excluded from this approach. A preoperative physical and instrumental evaluation was also performed to exclude any contraindications to femoral cannulation. All patients were operated on electively and had a normal left ventricular ejection fraction. The main preoperative characteristics of the patients and the MV pathology are summarized in Table 1.
The design of the study was two-institutional retrospective on a consecutive patient series. Preoperative and operative data were obtained by retrospective review of clinical and pathology reports using a custom-made database that is used daily for clinical data management and cross-checked with all medical charts. The data collected included the following: (a) demographics; (b) comorbidity risk factors; (c) operative data; (d) mortality; and (e) postoperative complications defined as myocardial infarction (new Q-wave or loss of R-wave progression across the chest leads; creatine kinase MB >10%), low cardiac output (a newly placed intra-aortic balloon pump or the use of inotropes for >48 hours), postoperative atrial fibrillation and pacemaker implant, bleeding requiring a rethoracotomy, respiratory insufficiency (mechanical ventilator support >48 hours), renal failure requiring dialysis, cerebrovascular accidents, and neurocognitive deficits (as determined by a staff neurologist).
Follow-up information on hospital survivors was collected by telephone interview during a 3-month interval that ended in January 2011, investigating survival, symptoms, long-term medical management, MR greater than 2+/4+ recurrence (by obtaining echocardiographic surveillance from the referring cardiologist), readmissions and reinterventions, and any surgery-related complications. Unsuccessful attempts to trace patients were followed by contact with a family member or with the referring physician.
All patients underwent MIMVR via a third or, more often, fourth interspace 6- to 8-cm right minithoracotomy, peripheral cannulation of the femoral vessels, external aortic clamping through the second or third intercostal space using the Chitwood transthoracic clamp (Scanlan International, Inc, Minneapolis, MN USA), and surgery under direct vision. Details on the minimally invasive operative approach and technical details of this repair are described elsewhere.4
Repair techniques for degenerative disease with posterior leaflet prolapse consisted of quadrangular resection (QR) and annuloplasty (AP) with or without sliding plasty; for anterior leaflet and bileaflet prolapse, edge-to-edge repair (EE) and AP. Repair techniques for endocarditic disease consisted of EE, perforation closure, and QR—all combined with AP.
Concomitant procedures were tricuspid valve surgery in 22 patients (12.3%), atrial septum defect or patent foramen ovale closure in five patients (2.8%), and atrial fibrillation ablation therapy in two patients (1.1%). Transesophageal echo-Doppler assessment of the valve was routinely undertaken before surgery and after weaning from cardiopulmonary bypass, and a transthoracic echocardiography was performed right before hospital discharge. Operative data are shown in Table 1.
Data are presented as mean ± SD and as percentages. Overall survival, freedom from reoperation, and MR recurrence (>2+/4+) were determined by Kaplan-Meier analysis and expressed as percentages of patients who were event free ± SE. One-sample log-rank test was used to assess the difference in MR recurrence (>2+/4+) between QR and EE repair patients. The linearized rates of redo, MR recurrence (>2+/4+), and overall mortality were expressed as a percent per year ± SE. Statistical analyses were performed with the NCSS 2000 software (Statistical Solutions Ltd, Cork, Ireland).
All patients survived the operation. No conversion to median sternotomy was required. Two patients (1.1%) of the QR group needed intraoperative revision of MVR, with one conversion to EE repair and one to cleft closure. Three patients (1.7%) required reoperation for bleeding: one from adhesions to the chest wall and two from the chest port access. Low cardiac output syndrome and respiratory failure were recorded in seven (3.9%) and in four (2.2%) patients, respectively. Myocardial infarction was recorded in four (2.2%) patients; atrial fibrillation in 32 (17.9%). Two patients (1.1%) had a pacemaker implant for atrioventricular block. There were no cases of neurological complications, acute renal failure, postoperative peripheral ischemia, and thoracic or groin wound infection. Deep venous thrombosis was observed in one case on postoperative day 6. Intensive care unit stay and operation-to-discharge length of stay were 34 ± 18 hours and 6.9 ± 4.2 days, respectively. All patients had a high degree of satisfaction in terms of comfort and cosmetic result. All patients were discharged with an MV regurgitation of less than 2+/4+.
Follow-up is 100% complete at a mean follow-up period of 5.3 ± 2.8 years (range, 13 months-11 years) for a total follow-up of 955 patient-years. There are 178 current survivors. One death for noncardiovascular disease was registered with a linearized rate of late mortality of 0.10% ± 0.10% per year. Seven patients (3.9%) are in atrial fibrillation, and the mean New York Heart Association class is 1.2 ± 0.5. One patient with preoperative diagnosis of endocarditis had a recurrence of mitral vegetation without MR onset. Four patients (2.2%) had more than one episode of pleuropericarditis that was treated with medical therapy or drainage during the first year after MIMVR. Recurrence of mitral regurgitation greater than 2+/4+ developed in six patients, with a linearized rate of 0.63% ± 0.26% per year, and two patients needed MV replacement (one for recurrence of mitral prolapse after 3 years from EE repair and one for mitral stenosis onset after 2 years from QR repair), with a linearized rate of redo of 0.21% ± 0.15% per year; both patients survived the reoperation. Overall survival, freedom from redo, and MR recurrence (>2+/4+) in QR repair and EE repair, as determined by Kaplan-Meier analysis, are reported in Figure 1. There was no difference in freedom from MR recurrence between QR and EE repair groups.
The expected achievement in MVR is to let the patient live as long as possible free from MR recurrence and reoperation. Along with the demonstration of the benefits obtained with early surgery in mitral insufficiency,5 a minimally invasive approach is more often requested, particularly by young patients, who are reluctant to undergo a major operation with no or few symptoms and who are more attracted by having a smaller scar and a faster return to active life. Skepticism surrounding MIMVR is still focused on the fact that incision size could potentially jeopardize the safety and exposure of established repair techniques with already proven durable long-term results. In a review and meta-analysis of 1641 patients, Modi and coworkers6 demonstrated that MIMVR is associated with equal mortality and neurological events despite longer cardiopulmonary bypass and aortic cross-clamp times, and that there is less morbidity in terms of reduced need for reoperation for bleeding, a trend toward shorter hospital stay, less pain, and faster return to preoperative function levels than conventional sternotomy-based surgery. Then Galloway and others,2 in a report of more than 1000 MIMVR performed through a right minithoracotomy, validate the long-term efficacy of the minimally invasive approach for MVR surgery in terms of freedom from reoperation or recurrent significant mitral insufficiency, which are almost identical to the results achieved with the standard sternotomy approaches.
In regard to operative outcomes, the present study confirms these data: in particular, the perioperative mortality rate was 0% in 179 patients, a value that compared very favorably with 1.1% in 92 MIMVR procedures reported by Ryan et al.7 However, MIMVR patients are often found to be a lower risk group (better ejection fraction, younger, less symptomatic) than patients diagnosed as having degenerative MR and scheduled for sternotomy, and our program of MIMVR selects mainly young patients who could benefit more from this strategy having at the same time the lowest risk of complications related to peripheral cannulation.
Several studies reported less time in hospital stay with an MIMVR approach.7,8 In our series, hospital stay was not always shorter (mean, 6.9 ± 4.2 days), depending strictly on the local health care system organization; postoperative mobilization and rehabilitation are more rapid in most of the experiences reported in the literature.
Only 12.3% of patients needed tricuspid valve surgery, which is contrast to data from most other large series such as those from Seeburger et al3 and Modi et al,6 where the rate is approximately 30%.3,6 We reconcile these differences with our results, considering that our criteria for concomitant tricuspid valve repair follow the evidence that the best surgical results in MV surgery are obtained in patients with no or minimal symptoms and no signs of left ventricle dysfunction. Accordingly, we advise early operation for patients with severe mitral regurgitation who have reparable valves, preferably before the development of symptoms or left ventricle dysfunction and so with no tricuspid valve involving.
Reoperation for bleeding was 1.7%, which is lower than that from Seeburger et al3 and Modi et al,6 which are all about 4% to 5% in thousands of patients.
Myocardial infarction and low output syndrome were recorded in 2.2% and 3.9%, respectively; we observed a higher incidence of these complications during the first 5 years (three patients vs one for myocardial infarction and six patients vs one for low output syndrome). For such a young patient population with normal coronaries, the issue was probably intraoperative myocardial protection. During the first year, a blood cardioplegia was used and then replaced with cold crystalloid cardioplegia.
In agreement with Felger et al,9 we did not observe a high incidence of postoperative atrial fibrillation (19.2%), as on the meta-analysis by Modi et al,6 where there was no significant difference between minimally invasive and standard sternotomy approaches (539 patients; odds ratio, 0.86; 95% confidence interval, 0.59–1.27; P = 0.45).
We did not register any postoperative stroke; these data depend mainly on the fact that we selected young patients with noncardiovasclular risks, and we practice an adequate clearing with continuous CO2 chest cavity insufflation. A possible limitation of our study is the underestimation of neurocognitive deficits. As a matter of fact, because much of the neurocognitive impairment is subtle, extensive preoperative neurocognitive testing is required to detect a postoperative complication. Because we did not perform preoperative tests, our study might have underestimated the incidence of neurocognitive deficits after MIMVR.
Until the studies of Galloway et al2 and Seeburger et al,3 published in 2009, limited data have been available regarding the long-term efficacy of MIMVR. Our clinical follow-up data confirm that the minimally invasive approach in the treatment of MV disease does not impair the durability of repair. In our series, two patients required MV replacement and six patients developed nontrivial recurrent mitral regurgitation, with a 10-year freedom from reoperation of 98.5% and MR recurrence (>2+/4+) of 89.8% for QR repair and 91.1% for EE repair.
Mohty et al10 have shown that patients with isolated posterior mitral leaflet prolapse had the best results in terms of MVR and freedom from reoperation rates. In our cohort, no difference in freedom from MR recurrence between posterior and anterior or bileaflet mitral prolapse groups was found.
In conclusion, our data confirm that MIMVR offers the same short- and long-term results as standard sternotomy, without any difference between posterior leaflet disease and anterior or bileaflet pathology. The use of the Alfieri stitch is clearly demonstrated; it gives long-term results equivalent to those of posterior leaflet repair, which traditionally has the lowest chance of reoperation of approximately 0.5% per year.
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This article describes a single-surgeon’s experience with minimally invasive mitral valve surgery over a 10-year period. Patients underwent a right minithoracotomy with peripheral cannulation, transthoracic aortic cross-clamping, and repair under direct vision. Most of the patients had degenerative disease, and a wide range of different repair techniques were used. The results from this experience were impressive. There was no intraoperative mortality, and all patients were discharged with less than 2+ mitral regurgitation. At 10 years’ follow-up, freedom from reoperation was 98.5% ± 1.1%. This retrospective single-surgeon experience demonstrates the excellent results that can be obtained by an experienced surgeon with minimally invasive mitral valve techniques. The group achieved these results with a very reproducible and cost-effective approach. It was impressive that freedom from mitral regurgitation recurrence was not different between posterior, anterior, and bileaflet prolapse groups as opposed to previous reports in the literature. The group’s experience suggests the potential advantages of the Alfieri stitch in patients with complex pathology.
Although these results are admirable and certainly comparable to selected reported results with standard sternotomy techniques in the literature, a true comparisonwould require a prospective randomized trial. For a full reviewof the literature on this subject, the recent International Society of Minimally Invasive Cardiothoracic Surgery consensus statement (Falk V, Cheng DCH, Martin J, et al. Minimally invasive versus open mitral valve surgery: a consensus statement of the International Society of Minimally InvasiveCardiothoracic Surgery ISMICS 2010. Innovations. 2011;6:66–76) provides a meta-analysis of the available data on minimally invasive mitral valve repair.
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