HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

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): Sotiris C. Stamou Robert Lowery Paul J. Corso Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Stamou, S. C. Articles by Corso, P. J. Search for Related Content PubMed PubMed Citation Articles by Stamou, S. C. Articles by Corso, P. J. Related Collections Valve disease

Ann Thorac Surg 2003;76:1101-1106
© 2003 The Society of Thoracic Surgeons

---

Original article: cardiovascular

Allogeneic blood transfusion requirements after minimally invasive versus conventional aortic valve replacement: a risk-Adjusted analysis

^a Section of Cardiac Surgery, Department of Surgery, Georgetown University Hospital, Washington, DC, USA
^b Section of Cardiac Surgery, Department of Surgery, Washington Hospital Center, Washington, DC, USA
^c Division of Cardiothoracic Surgery, SUNY Downstate Health Science Center, New York, New York, USA
^d Statistics and Computer Center, MedStar Research Institute, Washington, DC, USA

Accepted for publication April 18, 2003.

^* Address reprint requests to Dr Corso, Section of Cardiac Surgery, Department of Surgery, Georgetown University Hospital, Suite 4005 PHC, 3800 Reservoir Rd NW, Washington, DC 20007, USA.
e-mail: paul.j.corso{at}medstar.net

	Abstract

Top Abstract Introduction Patients and methods Results Comment References

 
BACKGROUND: Aortic valve replacement (AVR) through a partial sternotomy (mini-AVR) has been suggested to significantly reduce postoperative morbidity compared with conventional AVR. This study sought to investigate whether mini-AVR patients require fewer transfusions than patients who had conventional AVR.

METHODS: Of 511 patients who had AVR, 56 had mini-AVR and 455 had conventional AVR. A matched-case logistic regression analysis was used to adjust for these imbalances between groups.

RESULTS: No patient in the mini-AVR cohort required conversion to a conventional AVR. Cardiopulmonary bypass time was longer in the mini-AVR group compared with the conventional AVR group, with a median of 102 minutes (range, 78 to 119 minutes) versus 75 minutes (range, 61 to 96 minutes; p < 0.01) in the conventional AVR group. A total of 31 patients (55%) in the mini-AVR group and 336 patients (74%) in the conventional sternotomy group required transfusions during their hospital stay (p < 0.01). After adjusting for differences in preoperative risk factors, year of operation, and surgeon, by matching on propensity score, the differences were not statistically significant (odds ratio = 0.84, 95% confidence interval = 0.40 to 1.75, p = 0.63).

CONCLUSIONS: Mini-AVR produces better wound cosmesis and less surgical trauma but requires more time to perform. Matched-case analysis failed to show a significant difference in blood transfusion requirements after mini-AVR compared with the conventional AVR approach.

	Introduction

Top Abstract Introduction Patients and methods Results Comment References

 
Refinements in surgical techniques have reduced morbidity and mortality related to valve operations. Recently we have seen the advent of innovative, less invasive approaches for the surgical treatment of aortic valve disease [1, 2]. The premise for using minimally invasive techniques for aortic valve replacement (AVR) was that patient morbidity and potentially mortality could be reduced without compromising the excellent results of the conventional procedure. The rationale was that smaller surgical incisions are less traumatic and, therefore, produce less postoperative pain, shorter hospitalization, and faster recovery [3]. Other potential advantages of ministernotomy for AVR (mini-AVR) include improved cosmetic results and safer access in the case of reoperation [2, 4].

Most notable of all, however, is the reduction in postoperative hemorrhage and transfusion requirements [5]. Such a benefit is significant considering the increased morbidity and mortality associated with postoperative hemorrhage in addition to the risk for potential reoperation. However, previous studies reached this conclusion without using a risk adjustment methodology, which weakens their findings [1, 5–8]. The purpose of the current study was to compare perioperative clinical outcomes, transfusion requirements, and early mortality in patients who had mini-AVR versus conventional AVR by using a risk stratification model to adjust for potential differences between the two groups.

	Patients and methods

Top Abstract Introduction Patients and methods Results Comment References

 
Patients
The database of the Section of Cardiac Surgery at the Washington Hospital Center was used to identify all patients who had isolated AVR (n = 559) between January 1997 and December 2001. Of the 559 patients, 56 (10%) had mini-AVR, and 503 (90%) had conventional AVR. Forty-eight patients had undergone previous AVR operations. All of these patients were in the conventional AVR group. These patients were excluded from the analysis to reduce bias between the two groups. Therefore, the final sample size used in the analysis was 511 (455 [89%] conventional AVR and 56 [11%] mini-AVR). All the procedures were performed by the same group of cardiac surgeons.

Definitions
Diabetes was defined as a history of diabetes mellitus, regardless of disease duration, oral agents, or insulin use. Chronic renal insufficiency was defined as a serum creatinine value of at least 2.0 mg/dL. Recent myocardial infarction was defined as a myocardial infarction occurring within 24 hours before AVR. Low output syndrome was defined as the use of postoperative inotropic support for more than 24 hours. Prolonged ventilatory support was defined as pulmonary insufficiency requiring ventilatory support for more than 24 hours.

Postoperative stroke was defined as any new major (type II) neurologic deficit presenting in-hospital and persisting for more than 72 hours [9]. Prolonged length of stay was considered length of stay more than 7 days (50th percentile of the hospital stay). Allogeneic blood transfusions were considered transfusion of packed red blood cells only.

Operative techniques
Induction to anesthesia and intraoperative monitoring was the same in both groups of patients. Normothermic cardiopulmonary bypass and standard aortic cross-clamping was used, with the aorta cannulated proximal to the innominate vein and a two-stage venous return cannula placed into the right atrium. For myocardial protection, cold blood cardioplegia was perfused antegradely into the aorta and retrogradely through the coronary sinus. The ventricle was vented through the right superior pulmonary vein. Standard surgical techniques were used in all patients who had conventional AVR [10].

After induction of anesthesia, an external defibrillator (R2 Stat Padz; Zoll Inc., Burlington, MA) was placed on the patient. The operating table was turned counterclockwise 30 degrees. A transesophageal echocardiogram probe was placed, and the patient was then draped in the usual manner. A midline incision was begun just below the manubrium and carried 5 to 6 cm inferiorly. A skin flap was raised to provide access to the sternal notch superiorly. An inverted-L or T incision was then made in the fourth intercostal space with an oscillating saw. A standard reciprocating saw was then used to divide the sternum in the midline from the sternal notch to the fourth intercostal space incision. A small Finocchietto retractor was used for the sternum. The pericardial edges were sutured tightly to the skin edge. A 7- or 8-mm wire was used for reinforcement, and a flexible, small-profile aortic cannula was used to maximize space within a smaller wound. Likewise, a two-stage venous cannula, which had a flattened profile, was placed through a purse-string suture in the right atrial appendage. After securing the venous cannula, slight upward traction was placed on the cannula to facilitate placement of the purse-string suture in the body of the right atrium for the retrograde cardioplegia cannula. A long retrograde cannula was placed in the usual manner. A wire-reinforced catheter was placed into the left ventricle for venting through the right superior pulmonary vein. The patient was placed on cardiopulmonary bypass in the usual fashion. Vacuum-assisted venous drainage was not routinely used. The surgeon chose the valve and the technique of implantation. After valve implantation and during closure of the aortotomy, the heart was allowed to fill. Retrograde cold blood cardioplegia was given through the coronary sinus catheter, and the anesthesiologist was asked to inflate the lungs to remove air from the left ventricle. Venting of the heart was continued using a needle-vent in the ascending aorta. Pacing wires were placed on the right ventricle while the heart remained flaccid to allow easier access beneath the shelf of the undivided sternum. Transesophageal echocardiography was used to assess adequacy of the air removal as well as to evaluate early prosthetic valve and ventricular function. Either standard chest tubes or Blake drains were left within the pericardium and brought out through an intercostal space inferior to the wound.

Data analysis
Comparisons of baseline, operative, and postoperative variables were performed between the conventional AVR and mini-AVR groups. Data are expressed as percentages or as medians (25th –75th percentiles). Dichotomous variables were compared using the Mantel-Haenszel ² test or Fischer exact test when cell counts were less than 5. Continuous variables were compared using a Wilcoxon rank sum test. Left ventricular ejection fraction and case priority were compared using the Cochran-Armitage trend test. All tests were two-sided, and p values less than 0.05 were considered significant.

Logistic regression was used to calculate the probability of a patient's being selected for the mini-AVR group given a set of preoperative risk factors. These factors were identified from the literature as being associated with bleeding or death and included age, gender, African-American descent, diabetes, hypertension, congestive heart failure, recent myocardial infarction, previous cerebrovascular accident, carotid artery disease, chronic renal failure on hemodialysis, chronic obstructive pulmonary disease, ejection fraction, case priority, and use of preoperative anticoagulants (antiplatelet agents, heparin, warfarin, and thrombolytic agents) [11–13]. Model fit was evaluated using the Hosmer and Lemeshow goodness-of-fit statistic and residual analysis. The presence of linear dependencies or correlation among the independent variables (multicollinearity) was checked using diagnostics from ordinary logistic regression (tolerance and the variance inflation factor). Models that include variables that are highly correlated produce poor estimates of their effects on the dependent variable.

Propensity scores, or the probability of being selected for mini-AVR, were computed from these models [14]. Patients who had mini-AVR were randomly matched to those who had conventional AVR on propensity score, year of operation, and surgeon. Year of operation was included to control for variation in surgical practices over time, and surgeon was used to control for variation in the surgical team. By matching on propensity score, the mini-AVR and conventional cases have nearly equal proportions of the preoperative variables. The general estimating method was used in a logistic regression model to test the difference in the postoperative transfusion requirement rate between mini-AVR and conventional AVR groups, controlling for the correlation between matched sets [15].

	Results

Top Abstract Introduction Patients and methods Results Comment References

 
Patients
Preoperative patient characteristics varied between the two groups, with the mini-AVR patient population having lower Parsonnet risk scores (Table 1). Patients in the mini-AVR group tended to be younger, heavier, male, and had a higher ejection fraction than patients in the conventional AVR group. No differences were identified in the preoperative use of antiplatelet agents, heparin, warfarin, or thrombolytics. In the conventional AVR group, 364 (80%) patients had one of several types of mechanical valves, and 91 (20%) had tissue valves implanted, whereas in the mini-AVR group 34 (61%) patients had mechanical valves and the remaining 22 (39%) had tissue valves (Table 2). There were no emergent cases in the mini-AVR group. Mini-AVR was successful in all 56 patients in whom it was attempted, with no conversions to conventional AVR.

Early clinical outcome
Length of intensive care unit stay during the postoperative period was comparable for both groups. No mini-AVR patient had an intraaortic balloon pump placed preoperatively, and none required one postoperatively. Prolonged hospital stay (more than 7 days) occurred more frequently in patients who had conventional AVR, at a rate of 35% compared with 21% for the mini-AVR (p = 0.04) (Table 2). Hospital mortality rates were comparable in both groups, with a 5% mortality rate reported in both groups (p > 0.99). Causes of death are presented in Table 2.

Allogeneic blood transfusion requirements
Two hundred twenty-four (49%) conventional AVR patients and 16 (29%) mini-AVR patients were transfused in the operating room (Table 3). Postoperative transfusions were needed in 247 (54%) patients who had conventional AVR and 25 (45%) patients who had mini-AVR. A combined total of 336 (74%) patients in the conventional AVR group were transfused throughout their hospital stay, compared with 31 patients (55%) in the mini-AVR group (Table 3). Initially a statistically significant difference was found in operating room transfusion rates between the two groups. However, after adjusting for preoperative risk factors, year of operation, and surgical approach through matching, neither the postoperative nor intraoperative blood transfusion rates were statistically significant (odds ratio [OR] of transfusion postoperatively = 0.94, 95% confidence interval [CI] = 0.42 to 2.12], p = 0.88; OR of transfusion intraoperatively = 0.79, 95% CI = 0.45 to 1.40, p = 0.42; Table 4). Finally, for patients who received blood transfusions, the amount of blood received was comparable between the two groups (Table 3).

	Comment

Top Abstract Introduction Patients and methods Results Comment References

 
Surgical approaches
Since its introduction, interest in minimally invasive AVR has increased. Several new techniques have been developed as alternatives to the parasternal access incision, which required femoral cannulation, resection of the third and fourth rib cartilage, and ligation of the right internal mammary artery, as first described by Cosgrove and associates [1]. These other approaches include a right anterior thoracotomy [16], a partial superior sternotomy [17], a transverse sternotomy necessitating the division of both internal mammary arteries [2], an inverted T sternotomy into the manubrium [18], a reversed C incision [19, 20], a J incision [21, 22], a reversed Z incision [23], and a right-sided partial sternotomy [24]. We elected to use the inverted-L or T ministernotomy approach, because standardized cannulation and instrumentation could be used and there was no risk of sacrifice of the internal mammary arteries.

Proponents of mini-AVR have not only amply reported patients' increased satisfaction, resulting from better wound cosmesis, but have also reasoned that because of the reduced trauma, mini-AVR results in decreased postoperative pain [4, 6, 7, 16, 17], decreased infection rates [1, 2], decreased cost [6], faster recovery [1], and decreased need for ventilatory support [6, 7]. Therefore, it could be considered superior to conventional AVR .

Cosmetic result and postoperative pain
Cosgrove and associates [1] proclaimed that patients are resistant to procedures requiring median sternotomy, giving as an example the widespread acceptance of percutaneous transluminal coronary angioplasty, a procedure that carries a risk similar to that of coronary artery bypass grafting, an increased requirement for follow-up procedures, no long-term advantages over coronary artery bypass grafting, and less angina relief. In response they offer mini-AVR as an alternative to conventional AVR. Several recent studies have reported, however, that subjective evaluation of cosmesis is not influenced positively by mini-AVR, and when patients are informed objectively about the advantages and the disadvantages of each approach, only a small number decide to have a mini incision [20, 25].

Blood transfusion requirements
Several comparative studies have reported a significant reduction in postoperative hemorrhage and transfusion requirements after mini-AVR compared to conventional AVR [1, 5–8]. Cosgrove and associates [1] reported an average requirement of 1.1 U of red blood cells with a parasternal approach, whereas Cohn and colleagues [2] reported 2.2 U in 66% of their patients with the reversed T incision. Svensson and D'Agostino [21] described an average transfusion amount of 0.86 U, which decreased to 0.3 U in a subsequent study [22]. In a more recent study, Bonacchi and associates [6] reported that 37.5% of the patients who had mini-AVR required postoperative transfusions compared with 62.5% of the conventional AVR group.

In the current study, we sought to investigate whether a mini-AVR approach was associated with a lower need for allogeneic blood transfusion and to further validate and supplement the previous reports. A preliminary univariate analysis of our patients' blood requirements revealed a statistically significant difference in the odds of a patient receiving a blood transfusion (with fewer patients in the mini-AVR group receiving blood). A matched-case analysis was then performed to adjust for the difference in preoperative risk factors in a logistic regression model. When adjusted for preoperative risk factors, the lower odds of receiving a transfusion for the mini-AVR group were no longer statistically significant. The differences identified in the univariate analysis were likely due to selection bias favoring healthier lower-risk patients in the mini-AVR approach.

In previous studies, no preoperative risk adjustment was performed, and the results were based on univariate analysis only. Therefore, it is possible that encouraging results indicating reduced transfusion requirements with mini-AVR stem from an inherent selection bias in some of the studies. It is logical to assume that surgeons taking into account the limitations in exposure and prolonged cardiopulmonary bypass time associated with mini-AVR chose to perform it on healthier, more stable patients. Similarly, previous studies also failed to prove the theoretical advantages of mini-AVR [3, 20].

Prolonged cardiopulmonary bypass time
In our study, prolonged cross-clamp and cardiopulmonary bypass times were noted in the mini-AVR group compared with the conventional AVR group. Previous investigators found an association between prolonged cardiopulmonary bypass time and increased risk of postoperative stroke [26, 27]. Although the stroke rates were comparable between the two groups, no neuropsychological testing was done, which would have enabled us to assess more subtle changes in cognitive ability and behavior between the mini-AVR and conventional AVR approaches.

Therefore, given the possibility that there are no clearly established medical benefits for mini-AVR at this time, more research and evidence may be necessary before accepting and establishing the technique into the everyday armamentarium of the cardiac surgeon.

Study limitations
The short follow-up time (only until patient discharge) was a limitation of this study, as was the retrospective methodology. However, chart review and data entry were performed according to prespecified definitions, and data analysis was performed using propensity scores to adjust for differences in preoperative risk factors. Another limitation of the present study was the lack of assessment of postoperative pain, which would have enabled us to confirm or contradict the results of previous reports comparing postoperative pain after mini-AVR versus conventional AVR.

	References

Top Abstract Introduction Patients and methods Results Comment References

 

1. Cosgrove D.M., 3rd, Sabik J.F., Navia J.L. Minimally invasive valve operations. Ann Thorac Surg 1998;65:1535-1539.[Abstract/Free Full Text]
2. Cohn L.H., Adams D.H., Couper G.S., et al. Minimally invasive cardiac valve surgery improves patient satisfaction while reducing costs of cardiac valve replacement and repair. Ann Surg 1997;226:421-428.[Medline]
3. Szwerc M.F., Benckart D.H., Wiechmann R.J., et al. Partial versus full sternotomy for aortic valve replacement. Ann Thorac Surg 1999;68:2209-2214.[Abstract/Free Full Text]
4. Minale C., Reifschneider H.J., Schmitz E., Uckmann F.P. Minimally invasive aortic valve replacement without sternotomy. Experience with the first 50 cases. Eur J Cardiothorac Surg 1998;14(Suppl 1):S126-129.[Abstract/Free Full Text]
5. Tam R.K., Almeida A.A. Minimally invasive aortic valve replacement via partial sternotomy. Ann Thorac Surg 1998;65:275-276.[Abstract/Free Full Text]
6. Bonacchi M., Prifti E., Giunti G., Frati G., Sani G. Does ministernotomy improve postoperative outcome in aortic valve operation ? A prospective randomized study. Ann Thorac Surg 2002;73:460-466.[Abstract/Free Full Text]
7. Machler H.E., Bergmann P., Anelli-Monti M., et al. Minimally invasive versus conventional aortic valve operations: a prospective study in 120 patients. Ann Thorac Surg 1999;67:1001-1005.[Abstract/Free Full Text]
8. Klokocovnik T. Aortic and mitral valve replacement through a minimally invasive approach. Tex Heart Inst J 1998;25:166-169.[Medline]
9. Roach G.W., Kanchuger M., Mangano C.M., et al. Adverse cerebral outcomes after coronary bypass surgery. Multicenter Study of Perioperative Ischemia Research Group and the Ischemia Research and Education Foundation Investigators. N Engl J Med 1996;335:1857-1863.[Abstract/Free Full Text]
10. Kirklin J.W., Barrat-Boyes B.G. Hypothermia, circulatory arrest, and cardiopulmonary bypass. In: Kirklin J.W., Barrat-Boyes B.G., Jonas R.A., Kouchoukos N.T., eds. Cardiac surgery, 2nd ed New York: Churchill Livingstone, 1993:61-127.
11. Scott D., Berkowitz M.D., Christopher B., et al. Incidence and predictors of bleeding after contemporary thrombolytic therapy for myocardial infarction. Circulation 1997;95:2508.[Abstract/Free Full Text]
12. Bernstein A.D., Parsonnet V.A. Bedside estimation of risk as an aid for decision-making in cardiac surgery. Ann Thorac Surg 2000;69:823-828.[Abstract/Free Full Text]
13. Rao A.K., Pratt C., Berke A., et al. Thrombolysis in myocardial infarction (TIMI) trial–phase I. Hemorrhagic manifestations and changes in plasma fibrinogen and the fibrinolytic system in patients treated with recombinant tissue plasminogen activator and streptokinase. J Am Coll Cardiol 1988;11(1):1-11.[Abstract]
14. Rubin D.B., Thomas N. Matching using estimated propensity scores; relating theory to practice. Biometrics 1996;52:249-264.[Medline]
15. Diggle P.J., Liang K.Y., Zeger S.L. The analysis of longitudinal data. . New York: Oxford University Press, 1994.
16. Bennetti F.J., Mariani M.A., Rizzardi J.L., Bennetti I. Minimally invasive aortic valve replacement. J Thorac Cardiovasc Surg 1997;113:806-807.[Free Full Text]
17. Gundry S.R. Aortic valve surgery via limited incisions. In: Oz M.C., Goldstein D.J., eds. Contemporary cardiology: minimally invasive cardiac surgery. Totowa, New Jersey: Humana Press, 1999:124-205.
18. Gundry S.R., Shattuck O.H., Razzouk A.J., del Rio M.J., Sardari F.F., Bailey L.L. Facile minimally invasive cardiac surgery via ministernotomy. Ann Thorac Surg 1998;65:1100-1104.[Abstract/Free Full Text]
19. Aris A. Reversed "C" ministernotomy for aortic valve replacement. Ann Thorac Surg 1999;67:1806-1807.[Abstract/Free Full Text]
20. Aris A., Camara M.L., Montiel J., Delgado L.J., Galan J., Litvan H. Ministernotomy versus median sternotomy for aortic valve replacement: a prospective, randomized study. Ann Thorac Surg 1999;67:1583-1588.[Abstract/Free Full Text]
21. Svensson L.G., D'Agostino R.S. Minimal-access aortic and valvular operations including the "J" incision. Ann Thorac Surg 1998;66:431-435.[Abstract/Free Full Text]
22. Svensson L.G., D'Agostino R.S. "J" incision minimal-access valve operations. Ann Thorac Surg 1998;66:1110-1112.[Abstract/Free Full Text]
23. Nair R.U., Sharpe D.A. Minimally invasive reversed Z sternotomy for aortic valve replacement. Ann Thorac Surg 1998;65:1165-1166.[Abstract/Free Full Text]
24. Kasegawa H., Shimokawa T., Matsushita Y., Kamata S., Ida T., Kawase M. Right-sided partial sternotomy for minimally invasive valve operation: "open door method". Ann Thorac Surg 1998;65:569-570.[Abstract/Free Full Text]
25. Ehrlich W., Skwara W., Klovekorn W., Roth M., Bauer E.P. Do patients want minimally invasive aortic valve replacement?. Eur J Cardiothorac Surg 2001;7:714-717.
26. Newman M.F., Wolman R., Kanchuger M., et al. Multicenter preoperative stroke risk index for patients undergoing coronary artery bypass graft surgery. Circulation 1996;94:II-74-80.
27. Gilman S. Cerebral disorders after open heart operations. N Engl J Med 1965;272:489-498.

This article has been cited by other articles:

				M. L. Brown, S. H. McKellar, T. M. Sundt, and H. V. Schaff Ministernotomy versus conventional sternotomy for aortic valve replacement: a systematic review and meta-analysis. J. Thorac. Cardiovasc. Surg., March 1, 2009; 137(3): 670 - 679.e5. [Abstract] [Full Text] [PDF]

				M. Tabata, R. Umakanthan, L. H. Cohn, R. M. Bolman III, P. S. Shekar, F. Y. Chen, G. S. Couper, and S. F. Aranki Early and late outcomes of 1000 minimally invasive aortic valve operations Eur. J. Cardiothorac. Surg., April 1, 2008; 33(4): 537 - 541. [Abstract] [Full Text] [PDF]

				T. K. Rosengart, T. Feldman, M. A. Borger, T. A. Vassiliades Jr, A. M. Gillinov, K. J. Hoercher, A. Vahanian, R. O. Bonow, and W. O'Neill Percutaneous and Minimally Invasive Valve Procedures: A Scientific Statement From the American Heart Association Council on Cardiovascular Surgery and Anesthesia, Council on Clinical Cardiology, Functional Genomics and Translational Biology Interdisciplinary Working Group, and Quality of Care and Outcomes Research Interdisciplinary Working Group Circulation, April 1, 2008; 117(13): 1750 - 1767. [Abstract] [Full Text] [PDF]

				B. Murtuza, J. R. Pepper, R. DeL Stanbridge, C. Jones, C. Rao, A. Darzi, and T. Athanasiou Minimal Access Aortic Valve Replacement: Is It Worth It? Ann. Thorac. Surg., March 1, 2008; 85(3): 1121 - 1131. [Abstract] [Full Text] [PDF]

				M. Tabata, S. F Aranki, J. A Fox, G. S Couper, L. H Cohn, and P. S Shekar Minimally Invasive Aortic Valve Replacement in Left Ventricular Dysfunction Asian Cardiovasc Thorac Ann, June 1, 2007; 15(3): 225 - 228. [Abstract] [Full Text] [PDF]

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): Sotiris C. Stamou Robert Lowery Paul J. Corso Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Stamou, S. C. Articles by Corso, P. J. Search for Related Content PubMed PubMed Citation Articles by Stamou, S. C. Articles by Corso, P. J. Related Collections Valve disease