Cardiopulmonary Bypass Time
Cardiopulmonary bypass (CPB) time was significantly increased with mini-MVS versus conv-MVS (144 vs 111 minutes, WMD 33.0 minutes, 95% CI 18.9 to 47.1 minutes; 27 studies).4–8,11–15,17–19,21,22,25–29,31,32,34–38 There was significant heterogeneity across studies for this outcome. When subanalyzed, the two RCTs that reported this outcome also showed significantly increased CPB time with mini-MVS versus conv-MVS (Table 7).12,13
There was a significant increase in procedure time for mini-MVS compared with conv-MVS (4.5 vs 3.7 hours, WMD 0.79 hours, 95% CI 0.41 to 1.16 hours; 13 studies).5,6,12,14,15,18,21,25–27,34,37 The single RCT that reported this outcome showed no significant difference in procedure time between groups (WMD 0.24 hours, 95% CI −0.31 to +0.79 hours; one study).12 There was significant heterogeneity among the studies for this outcome (Fig. 9; Table 7).
Length of Ventilation
Ventilation time was significantly reduced for mini-MVS compared with conv-MVS (12.6 vs 19.9 hours, WMD −2.07 hours, 95% CI −3.39 to −0.75 hours; 18 studies).5,7,8,11,12,14,15,17,18,27–29,31,32,34–37 There was significant heterogeneity across studies for this outcome. The one RCT that reported this outcome showed no difference in the length of ventilation between mini- and conv-MVS (WMD −3.0 hours, 95% CI −7.4 to +1.4 hours) (Table 7).12
Length of Stay in ICU
Length of stay in ICU was significantly reduced for mini-MVS versus conv-MVS (1.6 vs 2.4 days, WMD −0.50 days, 95% CI −0.68 to −0.32 days; 18 studies).5,7,8,11,12,14,15,17,21,24,27–29,31,33,35–37 There was significant heterogeneity for this outcome. The one RCT that reported this outcome showed no significant difference in the length of stay in ICU between mini- and conv-MVS (WMD −0.30 hours, 95% CI −92 to +0.32 hours) (Table 7).12
Length of Stay in Hospital
Length of hospital stay was significantly reduced with mini-MVS versus conv-MVS (mean 6.9 vs 8.9 days, WMD −1.60 days, 95% CI −2.09 to −1.11 days; 26 studies).4,5,7,8,10–15,17,18,21,24,26–29,31–38 Subanalysis of the two RCTs reporting this outcome showed no difference in the length of stay in hospital between groups (WMD −0.04 days, 95% CI −0.8 to +0.7 days; two studies).4,13 There was significant heterogeneity among the studies for this outcome (Fig. 10; Table 7).
A study from the United States reported that compared with patients undergoing conv-MVS, patients undergoing mini-MVS had lower mean hospital charges (WMD −$11,430, 95% CI −$12,420 to −$10,440; one study), and lower mean hospital costs (WMD −$9,160, 95% CI −9,870 to −8,460; one study).8 Operating room charges in this study were procedure based, and this may not have accounted for the time-dependent costs. This is an important consideration, because operating room time for mini-MVS was approximately 1.6 hours longer than conv-MVS in this study. This could have masked the time-dependent cost variances. Another study from Slovenia reported that patients undergoing mini-MVS had lower mean costs than patients undergoing conv-MVS (WMD −664 Slovenia tolars, 95% CI −664 to −663 Slovenia tolars) (Table 8).17 None of the studies provided a comprehensive cost-effectiveness analysis of the incremental costs and benefits of mini-MVS versus conv-MVS.
Longer term risk of all-cause mortality was reported in few trials, and it did not show a significant difference between mini-MVS and conv-MVS at 1 year (0.9% vs 1.3%, RR 1.07, 95% CI 0.19 to 6.05; two studies),8,34 at 3 years (0.5% vs 0.5%, RR 1.06, 95% CI 0.07 to 16.79; one study)34 and up to 9 years (0% vs 3.7%, RR 0.19, 95% CI 0.01 to 3.64; one study).26 There was no significant heterogeneity among the studies, and no RCTs reported long-term mortality (Table 9).
Mitral Valve Leak or Insufficiency
No significant difference was found for the risk of long-term mitral valve leak between mini-MVS and conv-MVS (RR 9.5, 95% CI 0.4 to 226.7).8,21,34 There was significant heterogeneity among the studies, and no RCT reported long-term mitral valve outcomes. In addition, there was no significant difference in the grade of mitral insufficiency between mini-MVS and open-MVS (WMD 0.04, 95% CI −0.15 to +0.2).19,26,35 There was no significant heterogeneity among all these studies, and no RCT reported this outcome (Table 9).
There was no significant difference in the percentage of patients developing infective endocarditis between mini-MVS and open-MVS (0.5% vs 0.7%, RR 0.94, 95% CI 0.31–2.86; four studies).8,16,19,26 There was no significant heterogeneity among the studies, and no RCT reported this outcome (Table 9).
There was a small but significant decrease in NYHA class after 1 year for mini-MVS compared with conv- MVS (mean class 1.32 vs 1.52, WMD −0.26, 95% CI −0.27 to −0.25).19,26 There was no significant heterogeneity among the studies, and no RCTs reported this outcome (Table 9).
Freedom From Valve-Related Reoperation
There was no significant difference in freedom from reoperation between groups at 1 year (RR 1.03, 95% CI 0.97 to 1.10; one study).19 However, at 8 years, there was significant improvement in freedom from reoperation for mini-MVS compared with conv-MVS (RR 1.04, 95% CI 1.01 to 1.08; one study).16 Freedom from valve-related reoperation was significantly improved when all studies evaluating this outcome at 1 to 8 years follow-up were combined (RR 1.04, 95% CI 1.01 to 1.06; three studies); however, differences in follow-up between groups challenge the validity of this finding.16,19,26 There was no significant heterogeneity among the studies, and no RCT reported this outcome (Table 9).
Return to Normal Activity
Return to normal activity was significantly faster for mini-MVS versus conv-MVS (6.3 vs 12.3 weeks, WMD −4.96 weeks, 95% CI −6.39 to −3.52 weeks; three studies).4,18,34 There was significant heterogeneity across the studies for this outcome (Table 9).
Quality of Life
Quality of life was reported in only one observational study, and no significant difference was found in the change in quality of life between mini- and conv-MVS (Table 9).33
No study provided the cost or cost-effectiveness of mini-MVS versus conv-MVS over the long-term period.
This systematic review with meta-analysis suggests that mini-MVS is associated with decreased hemorrhage, blood product transfusion, atrial fibrillation, chest wound infection, ventilation time, ICU stay, hospital length of stay, and reduced time to return to normal activity, without detected adverse impact on long-term need for valvular reintervention and survival (though this meta-analysis was underpowered for long-term outcomes). However, an increased risk of stroke, aortic dissection or aortic injury, phrenic nerve palsy, groin infections, and increased CPB, cross-clamp, and procedure time was found.
No significant differences in mortality were found in this meta-analysis. This result is similar to another systematic review,1 which also found no difference in the overall mortality between mini- MVS and conv- MVS (odds ratio 0.46, 95% CI 0.15–1.42). Of note, an analysis of a large propensity-matched comparison study involving 8644 patients reported significant increase in the composite of major hospital morbidity or mortality with mini-MVS compared with conv-MVS (RR 1.17, 95% CI 1.05–1.32),37 raising the potential for concern about the safety of the minimally invasive approach. Unfortunately, other studies did not report death and major complications as a composite outcome, and we were unable to provide a synthesis for this outcome across all studies. Given that the above-mentioned study is large and propensity matched (in comparison to many of the studies in this analysis being unmatched retrospective comparisons), it is important to keep this potential for increased overall adverse events in mind. On the other hand, some centers contributing data to this propensity-matched comparison study were low-volume centers. Further contemporary comparative studies should be conducted to measure the overall risk of death and complications.
Our meta-analysis showed increase in stroke in mini-MVS compared with conv-MVS (RR 1.79, 95% CI 1.35 to 2.38). In contrast, Modi et al1 reported no difference in stroke between mini-MVS and conv-MVS (odds ratio 0.66, 95% CI 0.23–1.93). However, Modi included fewer studies in his meta-analysis and also included mini-sternotomy studies within the definition of mini-MVS. The cause of increased stroke with mini-MVS is not known and is beyond the scope of this meta-analysis. Potential hypotheses may be related to the restricted assess and technically challenging de-airing and/or the increase in procedure time and CPB time. In our subgroup analysis of aortic clamping approach, we found that the majority of increased strokes occurred in the studies using endoaortic cross-clamping. In the studies using primarily transthoracic clamping, there was no excess of strokes. This raises the hypothesis that mini-MVS using the endoaortic clamp may pose greater risk for patients compared with the transthoracic approach. However, it must be stressed that there may be other unexplored factors that could contribute to the increased risk of stroke, and this hypothesis needs further testing in well-conducted, adequately powered comparative trials before the true association can be concluded.
Phrenic Nerve Palsy
Our meta-analysis showed significant increase in the risk of phrenic nerve palsy/diaphragm elevation for mini-MVS versus conv-MVS (3% vs 0%). This may be a potentially serious adverse effect; however, the details of the clinical significance and duration of the palsy were incomplete.8,14 In addition, it is important to note that a number of the studies failing to report specifically on this outcome may have had zero events, although we could not assume this for the meta-analysis. Therefore, the interpretation of this result is limited by the small number of studies reporting on this outcome.
Pain and Functionality
It was anticipated that mini-MVS would be shown to induce less postoperative pain compared with conv-MVS. However, our meta-analysis found no significant difference in the VAS for postoperative pain between groups. Although the trend was toward reduction, the difference was very small with less than 1 point reduction on the VAS (WMD −0.07, −0.25 to 0.11 points on a 10-point VAS).21,23,33,34 Similarly, although intake of acetaminophen/oxycodone (in milligrams) was significantly less for mini-MVS compared with conv-MVS, the overall mean difference of 3 mg over the study period was very small and of questionable clinical relevance (WMD −3.35 mg, 95% CI-5.74 to −0.96 mg). There was no significant reduction in the use of morphine in the postoperative period.4 Therefore, although reduction in pain remains one of the key rationales for mini-MVS, it remains unproven by the current evidence base. Of all the studies published on mini-MVS versus conv-MVS, very few have reported on pain-related outcomes, and this should be an important part of any future research agenda. Meta-analysis of three studies showed faster return to normal activity of ∼5 to 6 weeks (6.3 ± 4.8 weeks vs 12.3 ± 3.8 weeks) for mini-MVS versus conv-MVS.4,18,34
Bleeding and Reoperation Outcomes
It is anticipated that the smaller incision of mini-MVS would lead to less hemorrhage; although there is concern that this could be counteracted by the longer procedure time required. Our meta-analysis showed a decrease in overall hemorrhage and chest tube drainage of ∼300 mL for mini-MVS compared with conv-MVS. This translated into significantly less patients receiving RBC and platelet transfusions. However, there was no statistically significant difference in the percentage of patients undergoing reoperation for bleeding between minimally invasive and conventional open mitral valve surgery.6,8,12,14,15,21,26,28,32,34–38 In contrast, reoperation for any cause (bleeding or any other reason) was significantly increased by ∼1% for mini-MVS versus conv-MVS (6.6% vs 5.5%, RR 1.20, 95% CI 1.01–1.41), although this was reported in just one study (propensity-matched comparison study involving 8644 patients).37
Our meta-analysis found a significant reduction in atrial fibrillation with mini-MVS compared with conv-MVS (absolute risk reduction 4%). This reduced risk of arrhythmia may be related to the less traumatic surgical approach used during mini-MVS resulting in lesser inducement of inflammatory mediators. Although atrial fibrillation was significantly reduced in our meta-analysis, there was no significant reduction in pacemaker implantation; however, this outcome was less commonly reported in the studies. Other cardiac outcomes of interest in our meta-analysis did not reach significant differences between groups, including myocardial infarction, left heart decompensation, hypotension, need for inotropes, intraaortic balloon pump implantation, ventricular rupture, cardiac tamponade, pericardial effusion, venous thromboembolism, arterial embolism, and in-hospital mitral insufficiency.
Our meta-analyses showed a significant increased risk of aortic dissection or iatrogenic aortic injury; however, the absolute risk increase of 0.2% was small (0.2% vs 0% for mini- vs conv-MVS, RR 6.04, 95% CI 1.06 to 34.47) The reason for the increased risk of aortic dissection and aortic injury remains unclear (ie, differences in clamping or added difficulties in manipulating the aorta during minimally invasive surgery).
Other Clinical Complications
Our meta-analysis showed no significant difference for postoperative renal failure or renal dysfunction between groups. Because few studies measured the incidence of renal failure, the current evidence remains underpowered to safely rule out whether important differences may exist between mini-MVS and conv-MVS for this clinically relevant outcome.
Pulmonary events were not significantly different between groups, including pneumonia, pneumothorax, pneumonitis, mediastinitis, and pleural effusion. Similarly, gastrointestinal complications did not differ between groups.
Infections and Scar Length
As expected, our meta-analysis found a significant decrease in sternal infections and dehiscence, but an increase in groin infections, hematoma, or hydrocele. Incision length was significantly reduced by ∼16 cm between groups, although these data were rarely provided for both groups in the studies and may not be reflective of the average practice difference between mini-MVS and conv-MVS. Only one study examined patient satisfaction with the scar and reported an improvement in satisfaction in patients undergoing mini-MVS compared with conv-MVS.
Overall Complications and Readmissions
Our meta-analyses showed no significance in the freedom from all hospital morbidity, quality of life, requirement of repeat procedure, and readmission within 30 days of postoperative period.
Conversion to open sternotomy was reported in 3.7% of patients; however, relatively few studies reported this outcome (12 studies, including 866 patients). The absence of reporting on this outcome does not guarantee that no conversions occurred, and the concern remains that retrospective studies are less likely to ascertain this information because it would be difficult to determine retrospectively from patient charts whether patients who received open sternotomy were originally intended to receive mini-MVS. The inadvertent inclusion of converted patients in the conventional open MVS arm may unfairly bias the results of this meta-analysis toward favoring mini-MVS because converted patients tend to have worse outcomes than patients undergoing their originally intended surgery.
Our meta-analyses found significantly increased cross-clamp time of ∼20 minutes, (95 ± 39 minutes vs 74 ± 36 minutes), increased CPB time of ∼33 minutes (144 ± 52 minutes vs 111 ± 52 minutes), and increased procedure time of close to 1 hour (4.5 ± 1.8 hours vs 3.7 ± 1.7 hours) for mini-MVS versus conv-MVS. Ventilation time was reduced by 2 hours (12.6 ± 17.7 hours vs 19.0 ± 36.3 hours). Length of stay in ICU was reduced by 0.5 days (1.6 ± 1.7 days vs 2.4 ± 2.4 days), and hospital stay was significantly reduced by ∼2 days (6.9 ± 4.2 days vs 8.9 ± 5.1 days) for mini-MVS versus conv-MVS. These results were of similar direction as in the systematic review by Modi et al,1 although the analysis by Modi et al had insufficient power to detect the difference for some of these outcomes. There was significant heterogeneity for each of these outcomes, which is likely due to the different learning curves across the different centers.
It is notable that in the randomized trials, the differences between groups for procedure-related outcomes and length of stay were less stellar than in the observational studies. For example, the randomized trials suggested that cross-clamp time was slightly decreased by 4 minutes (rather than increased by 23 minutes as in the observational studies), procedure time did not differ significantly, and length of stay in ICU and hospital were not reduced significantly for mini-MVS versus conv-MVS. The differences between randomized trials (with comparable groups at baseline) and nonrandomized trials (with potentially important differences between groups at baseline) may be related to the differences in surgeon experience with mini-MVS, different settings, and patient selection criteria (which may unfairly bias the results of observational studies if different criteria are used for mini- vs conv-MVS). The lack of differences in the randomized trials may also be related to their small sample sizes (n = 140 in total).
Few studies reported on the relative cost of mini-MVS versus conv-MVS. One study each from the United States and Slovenia suggested that mini-MVS was associated with significantly lesser costs than conv-MVS. However, the relevance of these findings to other settings in other countries remains uncertain. In addition, these studies were cost analyses only and did not attempt to calculate the incremental cost-effectiveness of mini-MVS versus conv-MVS over the time horizon of a patient lifetime, or even over the midterm, by including follow-up costs during the midterm.8,17
Longer Term Outcomes
Few studies provided long-term outcomes, and conclusions remain uncertain based on the results provided due to the paucity of data provided on completeness of follow-up in these studies. Of the studies that reported longer term outcomes (1 to 9 years of follow-up), there was no significant difference between groups for long-term mortality, quality of life, presence of mitral valve leak, grade of mitral insufficiency, risk of infective endocarditis, and need for reoperation. There was a small but significant decrease in NYHA class (WMD −0.26 class, 95% CI −0.27 to −0.25 class) and decreased need for reoperation for mini- versus conv-MVS; however, the clinical relevance and generalizability are uncertain given that the reductions were small and were based on a single study.
Strengths and Limitations
This meta-analysis is based on a comprehensive search of several databases to identify all relevant comparative data, and it complies with the latest methodologic recommendations for comprehensive systematic reviews of observational and randomized studies. In addition, this meta-analysis reports on all available clinically relevant and resource-related outcomes, rather than selectively reporting only a few outcomes. However, this meta-analysis is limited by the type of studies and the quality of the data provided in those studies. Most studies in this meta-analysis were retrospective series that compared minimally invasive experience at one center with their own (or others') experience with conv-MVS. In some studies, the series for mini- and conv-MVS were noncontemporaneous series, and the more historic nature of the conventional group may bias the results toward favoring mini-MVS if more contemporary settings provide better outcomes in general (regardless of which procedure would have been provided). In addition, in many series the surgeons who performed mini-MVS were different than the surgeons who provided conv-MVS. Differences in skill sets and differences in progression through the learning curve could bias the results for or against mini-mitral. Improved characterization of the learning curve is also needed. Documentation of the improved procedure-related outcomes over time due to the learning curve effect has been reported in at least one study.30 High-volume centers should perform comparative trials to determine whether better outcomes can be attained with experience.
Several outcomes were reported inconsistently across studies, including some of the most basic outcomes which would provide the rationale for mini-MVS including differences in pain, functionality, patient satisfaction, and quality of life. Also of key concern, most studies failed to provide data on outcomes beyond the patient's discharge from hospital.
Another significant limitation was the potential for overlap among the studies, which was difficult to ascertain in a number of cases due to insufficient reporting of dates of patient recruitment and repeated publications from the same authors or institutions. This issue requires further exploration to elucidate the independence among these patient sets. In addition, the largest data set comes from the STS database analysis by Gammie et al, and it may overlap significantly with some of the most recent studies from U.S. centers. Removing the smaller U.S. center studies from the graphs in the cases where both the study by Gammie et al and the potentially overlapping studies have reported on the same outcome did not have any material impact on the conclusions (because the weight of the study by Gammie et al was large, and the weight of the other singular studies was small). There are a number of U.S. studies that clearly did not overlap the study by Gammie et al because their date of recruitment was earlier than that covered by Gammie et al.
Implication for Practice and Further Research Required
Given the results of this imperfect evidence base, definitive conclusions regarding the overall benefit versus risk of mini-MVS versus conv-MVS are not possible. It seems that mini-MVS improves some important outcomes, but may increase the risk of other serious outcomes. Future studies should assess the volume-outcome relationship for mini-MVS versus conv-MVS. Further research should be encouraged. To ensure that any true differences between mini-MVS and conv-MVS can be detected, and that the magnitude of benefit versus risk can be measured objectively, adequately powered randomized trials should be undertaken to measure stroke, pain, patient satisfaction, overall major complications, need for reoperation, return to normal activity, and quality of life while in hospital and over the longer term. In addition, any future nonrandomized studies should increase validity through prospective and long-term follow-up for clinically important outcomes.
The authors are aware that recruitment for such a randomized trial may be perceived to be difficult in institutions where mini-MVS have been adopted before comparative evidence being available; however, this was equally true for other precedents in surgery, including the eventual conduct of randomized trials to test the widely accepted extracranial to intracranial (EC/IC) bypass to prevent ischemic stroke, even after it had been chosen as standard of care by many centres. Importantly, the eventual fair testing through randomized studies showed that EC/IC bypass surgery actually increased the risk of stroke compared with medical management.40 Although some centers report excellent short- and long-term results, these reports are usually noncomparative case series with uncertainty regarding consecutive recruitment. On the other hand, the studies in this meta-analysis include a mixture of new and older studies, and the early parts of the learning curve may have contributed to the results. Future study should evaluate the volume-outcome relationship for mini-MVS.39
Current evidence suggests that mini-MVS may be associated with decreased bleeding, blood product transfusion, atrial fibrillation, sternal wound infection, scar dissatisfaction, ventilation time, ICU stay, hospital length of stay, and reduced time to return to normal activity, without detected adverse impact on long-term need for valvular reintervention and survival beyond 1 year (although few studies reported long-term outcomes). However, these potential benefits for mini-MVS may come with an increased risk of stroke, aortic dissection or aortic injury, phrenic nerve palsy, groin infections/complications, and increased cross-clamp, CPB, and procedure time. Available evidence is largely limited to retrospective small cohort comparisons of mini-MVS versus conv-MVS that provide only short-term outcomes. Given these limitations, randomized controlled trials with adequate power and duration of follow-up to measure clinically relevant outcomes are recommended to determine the balance of benefits and risks.
The authors thank Ms. Aurelie Alger and Ms. Elizabeth Chouinard for their assistance in organizing the consensus conference. They thank Jennifer Podeszwa DeOliveira and Erin Boyce for facilitating literature searches and retrieval. They also thank Brieanne McConnell for her assistance with citation management.
1.Modi P, Hassan A, Chitwood WR Jr. Minimally invasive mitral valve surgery: a systematic review and meta-analysis. Eur J Cardiothorac Surg.
2.Moher D, Cook DJ, Eastwood S, et al. Improving the quality of reporting of meta-analysis of randomized controlled trials: the QUOROM statement. Lancet.
3.Stroup DF, Berlin JA, Morton SC, et al. Meta-analysis of observational studies in epidemiology: a proposal for reporting. Meta-analysis of Observational Studies in Epidemiology (MOOSE) group. JAMA.
4.Aklog L, Adams DH, Couper GS, et al. Techniques and results of direct-access minimally invasive mitral valve surgery: a paradigm for the future. J Thorac Cardiovasc Surg.
5.Bolotin G, Kypson AP, Reade CC, et al. Should a video-assisted mini-thoracotomy be the approach of choice for reoperative mitral valve surgery? J Heart Valve Dis.
2004;13:155–158; discussion 158.
6.Burfeind WR, Glower DD, Davis RD, et al. Mitral surgery after prior cardiac operation: port-access versus sternotomy or thoracotomy. Ann Thorac Surg.
7.Chaney MA, Durazo-Arvizu RA, Fluder EM, et al. Port-access minimally invasive cardiac surgery increases surgical complexity, increases operating room time, and facilitates early postoperative hospital discharge. Anesthesiology.
8.Chitwood WR Jr, Wixon C, Elbeery J, et al. Video-assisted minimally invasive mitral valve surgery. J Thorac Cardiovasc Surg.
9.Cohn LH, Adams DH, Couper GS, et al. Minimally invasive cardiac valve surgery improves patient satisfaction while reducing costs of cardiac valve replacement and repair. Ann Surg.
10.Cosgrove DM III, Sabik JF, Navia JL. Minimally invasive valve operations. Ann Thorac Surg.
11.de Vaumas C, Philip I, Daccache G, et al. Comparison of minithoracotomy and conventional sternotomy approaches for valve surgery. J Cardiothorac Vasc Anesth.
12.Dogan S, Aybek T, Risteski PS, et al. Minimally invasive port access versus conventional mitral valve surgery: prospective randomized study. Ann Thorac Surg.
13.El-Fiky MM, El-Sayegh T, El-Beishry AS, et al. Limited right anterolateral thoracotomy for mitral valve surgery. Eur J Cardiothorac Surg.
14.Felger JE, Chitwood WR Jr, Nifong L, Holbert D. Evolution of mitral valve surgery: toward a totally endoscopic approach. Ann Thorac Surg.
15.Folliguet T, Vanhuyse F, Constantino X, et al. Mitral valve repair robotic versus sternotomy. Eur J Cardiothorac Surg.
16.Galloway AC, Schwartz CF, Ribakove GH, et al. A decade of minimally invasive mitral repair: long-term outcomes. Ann Thorac Surg.
17.Gersak B, Sostaric M, Kalisnik J, Blumauer R. The preferable use of port access surgical technique for right and left atrial procedures. Heart Surg Forum.
18.Glower DD, Landolfo KP, Clements F, et al. Mitral valve operation via port access versus median sternotomy. Eur J Cardiothorac Surg.
1998;14 (suppl 1):S143–S147.
19.Grossi EA, LaPietra A, Ribakove GH, et al. Minimally invasive versus sternotomy approaches for mitral reconstruction: comparison of intermediate-term results. J Thorac Cardiovasc Surg.
20.Grossi EA, Galloway AC, Ribakove GH, et al. Impact of minimally invasive valvular heart surgery: a case-control study. Ann Thorac Surg.
21.Karagoz HY, Bayazit K, Battaloglu B, et al. Minimally invasive mitral valve surgery: the subxiphoid approach. Ann Thorac Surg.
22.McCreath BJ, Swaminathan M, Booth JV, et al. Mitral valve surgery and acute renal injury: port access versus median sternotomy. Ann Thorac Surg.
23.Mohr FW, Falk V, Diegeler A, et al. Minimally invasive port-access mitral valve surgery. J Thorac Cardiovasc Surg.
24.Nikolic A, Huskic R, Javovic LJ, et al. Our experience of minimally invasive surgery. Cor Europaeum.
25.Onnasch JF, Schneider F, Falk V, et al. Minimally invasive approach for redo mitral valve surgery: a true benefit for the patient. J Card Surg.
26.Raanani E, Spiegelstein D, Sternik L, et al. Quality of mitral valve repair: median sternotomy versus port-access approach. J Thorac Cardiovasc Surg.
27.Reichenspurner H, Boehm DH, Gulbins H, et al. Three-dimensional video and robot-assisted port-access mitral valve operation. Ann Thorac Surg.
28.Ruttmann E, Laufer G, Muller LC. Development of a minimally invasive mitral valve surgery program: the Innsbruck experience. Eur Surg.
29.Schneider F, Onnasch JF, Falk V, et al. Cerebral microemboli during minimally invasive and conventional mitral valve operations. Ann Thorac Surg.
30.Shinfeld A, Kachel E, Paz Y, et al. Minimally invasive video-assisted mitral and aortic valve surgery—our initial clinical experience. Isr Med Assoc J.
31.Srivastava AK, Garg SK, Ganjoo AK. Approach for primary mitral valve surgery: right anterolateral thoracotomy or median sternotomy. J Heart Valve Dis.
32.Suri RM, Schaff HV, Meyer SR, Hargrove WC III. Thoracoscopic versus open mitral valve repair: a propensity score analysis of early outcomes. Ann Thorac Surg.
33.Walther T, Falk V, Metz S, et al. Pain and quality of life after minimally invasive versus conventional cardiac surgery. Ann Thorac Surg.
34.Wang D, Wang Q, Yang X, et al. Mitral valve replacement through a minimal right vertical infra-axillary thoracotomy versus standard median sternotomy. Ann Thorac Surg.
35.Woo YJ, Nacke EA. Robotic minimally invasive mitral valve reconstruction yields less blood product transfusion and shorter length of stay. Surgery.
36.Ryan WH, Brinkman WT, Dewey TM, et al. Mitral valve surgery: comparison of outcomes in matched sternotomy and port access groups. J Heart Valve Dis.
37.Gammie JS, Zhao Y, Peterson ED, et al. Maxwell Chamberlain Memorial Paper for adult cardiac surgery. Less-invasive mitral valve operations: trends and outcomes from the Society of Thoracic Surgeons Adult Cardiac Surgery Database. Ann Thorac Surg.
2010;90:1401–1408, 1410.e1; discussion 1408–1410.
38.Mihaljevic T. Robotic mitral valve repair versus conventional approaches: potential realized. Presented at: AATS 90th Annual Meeting, May 1–5, 2010, Toronto, ON Canada.
39.Adams DH, Rosenhek R, Falk V. Degenerative mitral valve regurgitation: best practice revolution. Eur Heart J.
40.EC/IC Bypass Study Group. Failure of extracranial-intracranial arterial bypass to reduce the risk of ischemic stroke: results of an international randomized trial. N Engl J Med
Keywords:© 2011 Lippincott Williams & Wilkins, Inc.
Systematic review; Meta-analysis; Mitral valve surgery; Minimally invasive surgery