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Ann Thorac Surg 1999;68:1525-1528
© 1999 The Society of Thoracic Surgeons
a Minneapolis Heart Institute, Minneapolis, Minnesota, USA
Address reprint requests to Dr Arom, Cardiac Surgical Associates PA, Minneapolis Heart Institute and St. Paul Heart Lung Clinic, 920 E 28th St, Suite 420, Minneapolis, MN 55407
Presented at Evolving Techniques and Technologies in Minimally Invasive Cardiac Surgery, San Antonio, TX, Jan 22–23, 1999.
Abstract
Background. Valvular operations have followed coronary artery bypass grafting as procedures that are amenable to a minimally invasive approach. This study is a review of our brief experiences of less invasive valve surgery (LIVS) through a partial sternotomy approach and port-access valve surgery (PAVS) with an attempt to compare safety and cost-effectiveness of the surgical procedure and post-discharge follow-up.
Methods. Forty PAVS and 66 LIVS procedures performed between May 1996 and December 1998 were reviewed. The PAVS patients were younger, included more men, and had greater left ventricular function. Aside from these particular data points, there was no significant difference in preoperative variables between groups.
Results. Operating room time, surgery time, and cross-clamp time were significantly longer in the PAVS group. The operative mortality was 3% (LIVS) and 5% (PAVS). There was more new atrial fibrillation in LIVS (26% versus 5%, p = 0.009). Postoperative follow-up revealed 77% of LIVS and 76% of PAVS patients had returned to work and more than 95% of the retired patients in both groups had resumed their daily activities. Importantly, PAVS patients returned to work about 4 weeks sooner than LIVS patients did.
Conclusions. Early clinical outcomes are comparable between the two approaches, which indicates safety and importance of appropriate patient selection. More follow-up is required to assess postoperative pain and cosmetic satisfaction. At the present time, LIVS appears to be more cost-effective. Early return to work in the PAVS group may be the most important finding to further support the port-access approach. However, with practice pattern changes and increased intraoperative efficiencies, each of these two surgical techniques may continue to have an important role in the minimally invasive valve surgery arena.
Proponents of the minimally invasive approach to valve surgery believe a small anterior thoracotomy with port-access valve surgery (PAVS) leads to faster recovery when compared to a partial sternotomy of less invasive valve surgery (LIVS). Since the inception of PAVS, it is assumed that the procedure is associated with less pain and more satisfactory cosmetic results, and can be performed safely, effectively, and at lower cost. Our brief experiences of these two techniques are summarized in an attempt to compare the safety and cost-effectiveness of the surgical procedure and post-discharge follow-up.
Material and methods
A total of 106 consecutive patients who underwent PAVS or LIVS procedures between May 1996 and December 1998 were retrospectively studied. PAVS was initiated in our experience in September 1997. The data was collected using the Society of Thoracic Surgeons National Cardiac Surgery Database (STS.NCSD) variables and definitions. A total of 66 LIVS and 40 PAVS patients were included in the review. The PAVS patients had more men (68% versus 52%), were younger (mean age 58 ± 14 years versus 63 ± 18), and had a greater left ventricular function (61% versus 57%, p < 0.05). All other preoperative risk factors are listed in Table 1. As anticipated, there were more mitral valve surgeries (80%) in the PAVS group and more aortic valve surgeries (76%) in the LIVS group. The difference in the patient population is attributed to the patient selection and surgical approach used for each technique. In the LIVS group, 3% of the patients had a double-valve procedure. One patient in the LIVS group had a tricuspid valve leaflet repair and removal of a right atrial myxoma, and 1 patient had a tricuspid valvectomy and patent foramen ovale repair.
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2 and Fisher’s exact test. All intraoperative variables were compared using univariate analysis. A p-value of less than 0.05 is considered to be of statistical significance. Results
The operating room time, cross-clamp time, and perfusion times were significantly longer in the PAVS group (Table 2). The ventilation time and ICU times were comparable in both groups. The postoperative length of stay in PAVS and LIVS were similar (PAVS 7.1 ± 6.2, LIVS 8.4 ± 8.0, p not significant). For a more appropriate comparison of the two groups, operative mortalities were not included in the ventilation time, ICU times, or postoperative length of stay analysis. Operative mortality was 3% in LIVS and 5% in PAVS (p not significant). The LIVS group had more incidence of new atrial fibrillation (26% versus 8%, p < 0.05). There was no difference between the groups for stroke, heart block, pulmonary insufficiency, or new renal failure (Table 2). There were no complications from groin cannulation due to the use of the endoarterial return cannula in the PAVS group.
Within 30 days of the operative procedure, the readmission rate was 17% in the LIVS group and 10% in the PAVS group (p = 0.3). In the LIVS group, 3 patients were readmitted for pericardial window, 1 patient for pericardiocentesis, 1 patient for excess pericardial fluid requiring Lasix therapy (Hoechst Marion Roussel, Kansas City, MO), and 2 patients with atrial fibrillation. The other 4 patients were readmitted with noncardiac issues. In PAVS, 1 patient was readmitted with atrioventricular block and 1 was admitted requiring permanent pacemaker implantation. Two other patients were readmitted with noncardiac problems. Seventy-five percent of patients responded to 30-day follow-up done by phone or office visit. This follow-up revealed that 77% of the previously employed patients in the LIVS group returned to work within a mean of 7.5 weeks (range 4–13 weeks) and 76% in the PAVS group within a mean of 4.1 weeks (range 2–8 weeks, p < 0.001) of their operative procedure. Among retired or unemployed patients, 97% in LIVS and 100% in PAVS returned to their daily activities (eg, self-care, exercise) at 4–6 weeks follow-up.
Comment
Minimally invasive techniques for cardiac operations have recently been growing in popularity. Valvular operations have followed coronary artery bypass grafting as procedures that are amenable to the minimally invasive approach. In February of 1996, Carpentier and associates [1] successfully performed the first video-assisted mitral valve repair through a minithoracotomy incision. Three months later, Chitwood and colleagues [2] performed a direct-vision mitral valve repair, also through a minithoracotomy. Cosgrove and Sabik [3] reported their experience of performing aortic valve replacement through a right-sided parasternal incision.
Our minimally invasive surgery program for valvular operations began in May of 1996. The individual surgeon selected patients for appropriateness of the intended surgical technique to be used. For the LIVS group we utilized a small skin incision and partial sternotomy with a sternal spreading of 6 cm [4]. This technique is unique in that the right internal mammary artery is not sacrificed. Our cannulation technique is not different from conventional valve replacement or repairs, which utilize the same cannula for the aorta and right atrium. The superior pulmonary vein vent and coronary sinus catheter are inserted using procedures very similar to those of the conventional procedure, with only minor modifications. This approach can be used for all valve operations [5].
PAVS is performed using an Endo CPB (Cardiopulmonary Bypass) System (Heartport Inc, Redwood City, CA)[6] that utilizes five catheters: (1) an endoaortic clamp is a balloon-tip catheter which occludes flow through the ascending aorta, delivers cardioplegia, and vents the aortic root; (2) an endopulmonary vent drains blood from the pulmonary artery and decompresses the heart. This vent catheter is inserted through the internal jugular vein; (3) an endocoronary sinus catheter occludes the coronary sinus and delivers retrograde cardioplegia; (4) an endoarterial return cannula allows return of oxygenated blood from CPB. This cannula is inserted in the femoral artery; and (5) an endovenous drainage catheter is inserted in the femoral vein and placed at the junction of the right atrium and the superior vena cava. It drains blood from the heart into the oxygenator.
TEE is then used to identify the endovenous drainage catheter at SVC right atrium junction and endoaortic clamp in the aortic root. The coronary sinus catheter and pulmonary artery vent are inserted by the anesthesiologist. Formal training is required for the clinicians to become proficient with the Endo CPB System.
Our study was a consecutive, nonrandomized retrospective review. The only difference noted between the two groups was the mean ejection fraction of 57% for LIVS and 61% for PAVS (p < 0.05). Otherwise, there was no significant difference in preoperative demographic and risk factors among these two groups (Table 1). The majority of LIVS patients had aortic valve replacement while the PAVS were mitral valve replacements or repairs. Therefore, an argument could be made that these two groups are not comparable; however, the purpose of the review was to look at the safety, efficacy, cost-effectiveness, and short-term clinical outcome of each procedural technique.
Intraoperatively, the total operating room (OR) time (in and out of the operating room), surgery time (skin to-skin), perfusion time, and cross-clamp time were documented in the computerized OR record. The OR time and surgery times were longer in PAVS group (Table 2). The findings from this comparison confirmed our observation that it takes longer to perform the PAVS, in spite of the fact that both techniques use a limited approach through a small incision. The perfusion time and cross-clamp time were longer (109 ± 22 versus 91 ± 49 minutes and 73 ± 18 versus 60 ± 39 minutes, p < 0.05). We have found the difference to be attributed to the catheter preparation, setup and insertion time needed for the Endo CPB System. The OR time difference documented in this study could theoretically add another $1,500 to $3,000 per case to the hospital costs for the PAVS patients. Additionally, the disposable Endo CPB System adds an additional charge to the patient’s hospital costs for intraoperative equipment and disposables required for PAVS.
Other intraoperative parameters such as estimated blood loss, use of blood products, and inotropes, are collected retrospectively from the medical record.
The amount of blood loss and the use of temporary pacemaker were not different between the two groups, which suggests low risk and acceptable safety of both procedures.
The occurrence of new atrial fibrillation was more common in LIVS (26%) compared to PAVS (8%, p < 0.05). Cannulation of the right atrial appendage in LIVS most likely accounts for this difference, as cannulation in PAVS is through the femoral vein. We have determined that atrial fibrillation causes a prolonged hospital stay of on average 2.2 days in an ongoing continuous quality improvement process at our institution.
A partial sternotomy is unlike a full sternotomy incision. The full sternotomy incision is approximately 30 cm in length and the sternum is spread 25 cm wide, compared to a 6-cm long incision and sternal spreading of 6 cm in the partial sternotomy approach. We believe the partial sternotomy approach causes less damage to the muscles, ribs, and joints and could potentially result in less postoperative chest-wall pain. A partial sternotomy for minimally invasive surgery does not differ from the partial sternotomy used in a thymectomy operation. The typical thymectomy patient is discharged on the second postoperative day; thus it is not inconceivable that the LIVS patient could be discharged earlier as well. However, in our current practice, the "mind-set" has been to treat the sternotomy (total and partial) and the thoracotomy incision, with different postoperative restrictions. Also, our follow-up results showed that PAVS patients returned to work about 3 weeks sooner than the LIVS patients. With a change in practice in regard to activity and postoperative restrictions in the partial sternotomy patient, the LIVS and PAVS patients could be discharged from the hospital and return to work and their daily activities in a like manner.
Cosmetic results and early postoperative pain are difficult to evaluate during the early postoperative period. The smaller skin incisions often times have more ecchymosis initially but become small and unnoticeable 2 to 3 weeks after surgery. Evaluation of postoperative pain early in the hospital stay can also be misleading. In spite of receiving pain medications on a routine schedule, the same patient will grade incisional discomfort at different levels of pain even on the same day during the postoperative hospitalization. The evaluation of postoperative chest-wall pain and cosmetic result would be better assessed at 2–4 weeks after surgery.
PAVS requires formal training, capital equipment, and disposable expenditures, while LIVS is more "surgeon friendly" and can be performed without increased intraoperative resource utilization, translating into greater cost-effectiveness. Early clinical outcomes within 30 days are comparable between the two surgical approaches, which indicates safety and the importance of appropriate patient selection. More follow-up of the surgical techniques is required to assess postoperative pain and cosmetic satisfaction in a thoracotomy versus a partial sternotomy approach. At the present time, LIVS appears to be more cost-effective. Early return to work in the PAVS group may be the most important finding to further support the port-access approach. However, with practice pattern changes and increased intraoperative efficiencies, each of these two surgical techniques may continue to have an important role in the minimally invasive surgery arena.
References
This article has been cited by other articles:
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  W. R. Chitwood Jr. and E. Rodriguez Minimally Invasive and Robotic Mitral Valve Surgery Card. Surg. Adult, January 1, 2008; 3(2008): 1079 - 1100. [Full Text]
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 W. F. Northrup III, R. W. Emery, D. M. Nicoloff, T. J. Lillehei, A. R. Holter, and D. P. Blake Opposite trends in coronary artery and valve surgery in a large multisurgeon practice, 1979-1999 Ann. Thorac. Surg., February 1, 2004; 77(2): 488 - 495. [Abstract] [Full Text] [PDF]
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W. R. Chitwood Jr. and L. W. Nifong Minimally Invasive and Robotic Valve Surgery Card. Surg. Adult, January 1, 2003; 2(2003): 1075 - 1092. [Full Text]
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P. Schroeyers, F. Wellens, R. De Geest, I. Degrieck, F. Van Praet, Y. Vermeulen, and H. Vanermen Minimally invasive video-assisted mitral valve surgery: our lessons after a 4-year experience Ann. Thorac. Surg., September 1, 2001; 72(3): S1050 - 1054. [Abstract] [Full Text] [PDF]
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