Minimally Invasive Coronary Artery Bypass Grafting Decreases - NCBI

ANNALS OF SURGERY Vol. 225, No. 6, 805-811 © 1997 Lippincott-Raven Publishers

Minimally Invasive Coronary Artery Bypass Grafting Decreases Hospital Stay and Cost Robert C. King, M.D., T. Brett Reece, B.A., Janet L. Hurst, M.S.N., M.B.A., Kimberly S. Shockey, M.S., Curtis G. Tribble, M.D., William D. Spotnitz, M.D., and Irving L. Kron, M.D. From the Division of Thoracic and Cardiovascular Surgery, Department of Surgery, University of Virginia Health Sciences Center, Charlottesville, Virginia

Objective The authors performed a retrospective cost analysis for patients undergoing revascularization of their left anterior descending (LAD) coronary artery either by standard coronary artery bypass grafting (CABG), percutaneous transluminal coronary angioplasty (PTCA), or minimally invasive coronary artery bypass grafting (MICABG).

Summary Background Data Minimally invasive CABG has become a safe and effective alternative treatment for singlevessel coronary artery disease. However, the acceptance of this procedure as a routine alternative for the treatment of coronary artery disease will depend on both long-term graft patency rates as well as a competitive market cost.

Methods The authors conducted a retrospective analysis of three patient groups undergoing LAD coronary revascularization from January 1995 to July 1996. Ten patients were selected randomly from this period after PTCA of an LAD lesion with or without stenting. Nine patients underwent standard CABG on cardiopulmonary bypass with a left internal mammary artery. Nine patients received MICABG via a limited left anterior thoracotomy and left internal mammary artery to LAD grafting without the use of cardiopulmonary bypass.

Results Percutaneous transluminal coronary angioplasty (n = 10) was unsuccessful in two patients. One patient in the MICABG group (n = 9) was converted successfully to conventional CABG because of an intramyocardial LAD and dilated left ventricle. There was no operative morbidity or mortality in any group. Average length of stay postprocedure was decreased significantly for both the MICABG and PTCA groups when compared with that of conventional CABG (n = 9) (2.7 + 0.26, p = 0.009, and 2.6 + 0.54, p = 0.006, vs. 4.8 + 0.46, respectively). Total hospital costs for the MICABG and PTCA groups were significantly less when compared with those of standard CABG ($10,129 + 1104, p = 0.0028, and $9113 + 3,039, p = 0.0001, vs. $17,816 + 1043, respectively). There were no statistically significant differences between the MICABG and PTCA groups.

Conclusions The final role of minimally invasive CABG is unclear. This procedure is clearly cost effective when compared with that of PTCA and conventional CABG. The long-term patency rates for MICABG will determine its overall efficacy.

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The operative techniques necessary for performing minimally invasive coronary artery bypass grafting (MICABG) originated 20 to 30 years ago. Both coronary artery revascularization and valvular repair have been performed via thoracotomy. In fact, this approach may be preferable to sternotomy in selected patients undergoing redo cardiac operation. 1-3 Likewise, coronary artery bypass grafting (CABG) without the use of cardiopulmonary bypass (CPB) was first investigated in the 1960s.45 At that time, however, most surgeons accepted the morbidity of CPB to ensure the technical precision afforded by a motionless heart. Still, some surgeons have continued to report series of patients who have undergone bypass grafting without the use of CPB.69 Once surgical procedures are determined to be safe, today's medical economic pressures greatly influence the application of surgical technology. Surgeons from all specialties are re-evaluating their techniques and practices in an effort to minimize cost while maximizing patient outcome. One obvious method for reducing costs would be the adoption of procedures that would minimize patient morbidity and postoperative length of stay. Minimally invasive surgery with or without the use video-assisted technology has developed to suit this purpose. Maximized technical proficiency has led several cardiac surgeons to investigate the application of minimally invasive techniques to coronary revascularization. Recently, several series have documented the safety and efficacy of MICABG.10- 16 Renewed interest in MICABG stems from the cardiac surgeon's desire to decrease patient morbidity and discomfort while improving the cost-benefit ratio for coronary revascularization. Routine CPB has been shown to lead to increased incidences of neurologic, hematologic, pulmonary, and renal complications.17-22 Additionally, post-CPB physiology necessitates an extended and complicated postoperative course.23-25 The pathophysiology of CPB therefore appears to directly increase postoperative length of stay and hospital costs. Avoidance of CPB could possibly decrease both length of stay and total hospital cost per procedure for single-vessel CABG by as much as 50%. The purpose of this study was to compare the costbenefit ratio of three methods of coronary revascularization for significant left anterior descending (LAD) lesions. We hypothesized that MICABG would prove superior to Presented at the 108th Annual Meeting of the Southern Surgical Association, December 1-4, 1996, Palm Beach, Florida. Address reprint requests to Irving L. Kron, M.D., Division of Thoracic and Cardiovascular Surgery, Department of Surgery, Box 310, University of Virginia Health Sciences Center, Charlottesville, VA 22908. Accepted for publication December 13, 1996.

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Table 1. PATIENT DEMOGRAPHICS PTCA

Demographics No. Male Female Age (yr) Ejection fraction (%) CPB time (min) X-clamp/ischemia (min) Mortality Morbidity Reoperation (75% circumferential lesion of their LAD coronary artery with similar cardiac ejection fractions and New York Heart Association classification. Patient demographics for each group are summarized in Table 1.

Statistical Analysis Total hospital costs and postprocedure length of stay for each group were determined and compared using analysis of variance. Significant differences were reported for p < 0.05.

Surgical Procedure Minimally invasive coronary artery bypass was performed in the following fashion. The patient was prepared and draped as if undergoing standard CABG. The perfu-

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LEFT INTERNAL MAMMARY ARTERY

THIRD RIB REFLECTED

COSTAL

CARTI LAGE EXCISED

/1\

Figure 2. Once the incision is completed, exposure to the heart is increased by removing the fourth rib or dividing the third rib or both. Figure 1. The limited left anterior thoracotomy incision site for the minimally invasive coronary artery bypass grafting procedure. The skin is incised directly over the fourth rib beginning at the lateral border of the sternum. The incision is approximately 6 to 8 cm in length.

sion team was available immediately, but the CPB pump was left unprimed. External defibrillator pads were applied to the patient with the use of a double-lumen endotracheal tube or pulmonary artery catheter depending on patient preoperative evaluation. Esmolol at 50 ,ug/kg per minute was instituted at the induction of anesthesia and titrated to effect to maintain the heart rate at 50 beats per minute. A 7- to 10-cm incision then was made over the left fourth rib starting at the left lateral border of the sternum (Fig. 1). The costal cartilage of the fourth rib then was removed to improve exposure (Fig. 2). The left internal mammary artery (IMA) was dissected free under direct visualization to the level of the second rib and extending inferiorly to its bifurcation. The patient then was heparinized with 100 units/kg of intravenous heparin on completion of IMA takedown. The mammary then was transected and dilated with intraluminal papaverine. The pericardium then was incised longitudinally and the LAD identified. Proximal and distal control of the LAD were achieved with 5-0 prolene snares passed in Potts fashion (Fig. 3). Once the patient was determined to be stable after LAD occlusion, coronary arteriotomy was carried out in usual fashion. The IMA-to-LAD anastomosis was performed with a running 7-0 prolene suture. After assurance of anastomotic integrity, Doppler ultrasound was used to assess flow. A single intrapleural chest tube was placed after completion of the procedure, and the wound was closed. Pain control could be facilitated by the use of intercostal anes-

thesia. Patients were extubated in the operating room after the completion of the procedure and returned to the cardiac intensive care unit for overnight monitoring. The single chest tube was pulled the next morning, and the patient was transferred to a normal room on the medical floor within 24 hours, ambulatory and ready to start a regular diet. Single-vessel CABG was carried out in usual operative fashion via median sternotomy with the use of CPB. All patients analyzed in this series received a left IMA-toLAD single-vessel bypass. Postoperative care was dictated by the critical pathways in place at our institution. THIRD RIB REFLECTED

IMA

COSTAL CARTILAGE EXCISED

ON FOURTH

__

=

RIB -~

LAD

TRACTION SUTURES

Figure 3. A bloodless field is prepared on the beating heart by snaring the left anterior descending both proximally and distally to the graft site with 4-0 prolene sutures. Additional stabilization of the field can be obtained by passing stay sutures through the epicardium of the left ventricle and securing them. Left internal mammary artery to left anterior descending anastomosis is completed with 7-0 prolene sutures in usual running fashion.

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Table 2. RESULTS Group

LOS Total (days)

LOS Postprocedure (days)

Charge (U.S. dollars)

Total Cost (U.S. dollars)

PTCA (n = 10) MICABG (n = 9) CABG (n = 9)

3.60 ± 0.82 2.70 ± 0.26 4.78 ± 0.44

2.62 ± 0.54* 2.71 ± 0.26t 4.83 ± 0.46

10,178 ± 2069 16,134 ± 1941 29,447 ± 1417

9113 ± 3039t 10,129 ± 1014§ 17,816 ± 1043

PTCA = percutaneous transluminal coronary angioplasty; MICABG = myocardial infarction coronary artery bypass graft; CABG = coronary artery bypass graft; LOS = length of stay. * p = 0.006. t p = 0.009. t p = 0.0001. § p = 0.0028.

Percutaneous transluminal coronary angioplasty of discrete LAD lesions was carried out by the interventional cardiology staff at our institution from January 1995 to July 1996. Patients who received stent placement also were considered in this group. A cohort of ten patients was selected for comparison during this period by randomly generated numbers on a Hewlett-Packard 48S hand-held calculator (Hewlett-Packard Company, Sinapore).

RESULTS There was no operative or procedure-related mortality for any group. Two of the ten patients who underwent PTCA were readmitted within 3 months of their primary procedure for repeat angioplasty. The costs for these repeat procedures were included in the final cost analysis for this study. One patient did not respond to PTCA and eventually underwent routine CABG. This patient was not billed for the cost of the PTCA, and the cost of the patient's bypass grafting was not considered in this analysis. One patient in the MICABG group was converted successfully to conventional CABG because of an intramyocardial LAD and dilated left ventricle. All other patients receiving single-vessel bypass were revascularized successfully without graft failure. Both the PTCA group (2.6 + 0.54 days, p = 0.006) and the MICABG group (2.7 + 0.26 days, p = 0.009) had a significantly decreased postprocedure length of stay when compared with that of the standard CABG group (4.8 + 0.46 day). Similarly, total hospital costs for both the PTCA group ($9113 + 3039, p = 0.02) and the MICABG group ($10,129 + 1014, p = 0.0028) were significantly lower than those for the standard CABG group ($17,816 + 1043). There were no statistical differences between the MICABG and PTCA groups (Table 2).

DISCUSSION Minimally invasive CABG is a safe and effective alternative for LAD revascularization. 10-16 Several technolo-

gies are being developed to facilitate the performance of this procedure. Port access, "endoCPB," myocardial stabilization devices, and even balloon clamp administration of cardioplegic solutions are evolving technologies aimed at increasing the application of minimally invasive cardiac procedures.122627 Indeed, all major coronary regions are approachable via thoracotomy or thoracoscopy or both. However, only a few authors have reported successful multivessel MICABG through the use of a T graft (left IMA and radial artery segment) or gastroepiploic artery.8' 6 Meanwhile, some centers have reported successful mitral valve repair via port access or small thoracic incisions or both with the use of femoral access

CPB.28 Despite the promising preliminary studies, long-term data concerning the patency of grafts performed on a beating heart have not been collected. Some think that operating on a beating heart may present a technical challenge to the longevity of graft patency. Preliminary studies seem to support the need for technical excellence during distal anastomosis on moving coronary targets.29 Several centers currently are investigating both mechanical and pharmacologic means for immobilizing the heart without using CPB.26 The principal reason for renewed interest in MICABG is to provide a safe and effective alternative for myocardial revascularization while reducing the physiologic sequelae and hospital costs associated with CPB. Avoidance of CPB should decrease the incidence of associated operative complications and circumvent iatrogenically induced bleeding diathesis and hypervolemia. No patients undergoing MICABG in our limited series required perioperative blood transfusion. In this retrospective analysis, MICABG decreased both postoperative length of stay and hospital costs when compared with those of standard single-vessel CABG with CPB for two similar cohorts of patients. There were no statistically significant differences in costs or postprocedural length of stay between MICABG and PTCA when

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redo procedures (20% of patients undergoing angioplasty will need a repeat procedure within 6 months.32 A limited anterior thoracotomy probably does not confer any advantage over median sternotomy as far as postoperative pain is considered. A purely thoracoscopic approach could potentially increase patient postoperative comfort. We think that the patient benefits derived from normal intraoperative cardiopulmonary physiology outweigh the discomfort caused by this approach. The exact role for MICABG remains to be defined fully. We currently support its use in the patient who has single-vessel disease either in the LAD or RCA distribution and is at risk for PTCA or who has experienced restenosis after PTCA. We believe that MICABG is safe and effective and offers a practical solution to the increased costs and morbidity associated with standard CABG.

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Discussion DR. W. RANDOLPH CHITWOOD, JR (Greenville, North Carolina): Dr. Cameron, Dr. Copeland, Members, and Guests. Again, I appreciate the authors' consideration by providing me with their manuscript well in advance of this meeting. Dr. Kron and coauthors have shown that new minimally invasive coronary bypass grafting techniques can be much more cost effective