Interact CardioVasc Thorac Surg 2009;9:214-217. doi:10.1510/icvts.2009.203059
© 2009 European Association of Cardio-Thoracic Surgery
Institutional report - Cardiac general |
Does obesity affect operative times and perioperative outcome of patients undergoing totally endoscopic coronary artery bypass surgery?
Dominik Wiedemanna,*,
Thomas Schachnera,
Nikolaos Bonarosa,
Felix Weidingera,
Christian Kolbitscha,
Guy Friedricha,
Günther Laufera and
Johannes Bonattib
a Innsbruck Medical University, Innsbruck, Austria
b University of Maryland, Baltimore, USA
Received 21 January 2009;
received in revised form 26 April 2009;
accepted 27 April 2009
 Dr. Bonatti received research grants and consulting fees from Intuitive Surgical.
*Corresponding author. Department of Cardiac Surgery, Innsbruck Medical University, Anichstrasse 35, A-6020 Innsbruck, Austria, Tel.: +43 512 504 80786; fax: +43 512 504 22528.
E-mail address: dominik.wiedemann{at}i-med.ac.at (D. Wiedemann).
 |
Abstract
|
|---|
More and more patients undergoing coronary artery bypass grafting (CABG) are overweight. This patient group suffers from wound healing problems more often than normal-weight patients. Therefore, avoiding sternotomy in obese patients by using an endoscopic technique could be a promising approach. Robotic technology enables totally endoscopic coronary artery bypass grafting (TECAB) procedures. We investigated whether the intra-operative-times or perioperative-outcome after TECAB-procedure are negatively affected by obesity. Patients [n=127, 101 male, 26 female, median age 59 (31–77) years], undergoing arrested-heart TECAB procedure were enrolled. The median body mass index (BMI) in this patient cohort was 26 (19–38). In detail, 27 patients were normal-weight (BMI 25 kg/m2), 67 patients were overweight (BMI 25.1–30 kg/m2), 29 patients were obese (BMI 30.1–33.9 kg/m2) and four patients were morbidly obese (BMI 34 kg/m2). There was no correlation between BMI (1) left internal mammary artery (LIMA) takedown-time [Spearman-rank correlation coefficient (R)=0.02; P=n.s.], (2) lipectomy and pericardiotomy-time (R=0.042, P=n.s.), (3) total operative-time (R=–0.083: P=n.s.), (4) cardiopulmonary-bypass-time (R=–0.012; P=n.s.), (5) aortic-endoocclusion-time (R=–0.055; P=n.s.), (6) mechanical-ventilation-time (R=0.001, P=n.s.), (7) length of ICU-stay (R=0.04; P=n.s.), (8) length of hospital-stay (R=–0.103; P=n.s.) or (9) occurrence of intra- and/or postoperative adverse events. In overweight, obese but also morbidly obese patients the TECAB procedure did not increase operative times or the rate of intra- or postoperative complications. This patient group, therefore, benefits from this less traumatic version of coronary surgery.
Key Words: Obesity–coronary artery disease; Coronary artery bypass grafting; Endoscopic surgery; Robotic surgery
|
1. Background
|
|---|
Over recent decades, improvement in socioeconomic conditions has led to an expansion of the overweight population. The prevalence of obesity in the USA and also in Europe continues to increase among both males and females in all age groups. Obesity is an important risk factor for various chronic diseases and an important public health issue [1]. It is also a pre-disposing factor for coronary heart disease and associated with hyperlipidemia, diabetes mellitus (metabolic syndrome), arterial hypertension, and other cardiac risk factors. Therefore, it is evident that an increasing proportion of patients undergoing coronary artery bypass grafting (CABG) is obese and is thought to carry a higher mortality and morbidity associated with surgery. This rather reasonable hypothesis is not true for every outcome variable. The Northern New England Cardiovascular Disease Study Group found that obesity as an isolated risk factor did not significantly increase postoperative complications apart from sternal and superficial wound infection [2]. The latest analysis of the National Cardiac Surgery Database of the Society of Thoracic Surgeons, using data from CABG operations in over 550,000 patients, indicated that morbid obesity [body mass index (BMI)40 kg/m2] remains an independent predictor of increased operative mortality in patients undergoing CABG [3]. Moreover, there is evidence that mid-term survival and long-term outcomes after the CABG may be adversely affected by obesity [4].
Because of technical difficulties in cardiac surgery, endoscopic and minimal invasive procedures made their way into this field rather late. Today only specially experienced centers perform totally endoscopic coronary artery bypass (TECAB) and little information is available about the role of endoscopic CABG for obese patients [5–8].
Therefore, the aim of the present study was to evaluate the influence of the BMI on operative times, length of stay, and perioperative outcome in TECAB patients.
|
2. Patients and methods
|
|---|
From 2001 to 2008 at a single center, patients undergoing single left internal mammary artery (LIMA) to left anterior descending artery (LAD) grafting with the arrested heart TECAB (AH-TECAB) procedure were analyzed. Demographic data are listed in Table 1.
According to the BMI, patients were categorized as normal weight (25 kg/m2), overweight (BMI: 25.1–20 kg/m2), obese (BMI: 30.1–33.9 kg/m2), or morbidly obese (34 kg/m2).
2.1. Surgical technique
After positioning of the patient in a 30° right lateral position and setup of the da VinciTM Robotic System (Intuitive Surgical Inc, Sunnyvale, CA) the camera port was inserted in the 5th intercostal space in anterior axillary line while the left lung was deflated. CO2 insufflation was started with a pressure of 6–12 mmHg. Under thoracoscopic vision the robotic instruments were inserted into the 3rd and 7th intercostal spaces.
The first step of the endoscopic procedure was the exposure of the LIMA from the endothoracic fascia and the transverse thoracic muscle. IMA harvesting was performed in a semi-skeletonized fashion using the electrocautery and endoscopic clips. Before placement of an occluding bulldog clamp Heparin (300 IE/kg i.v.) was administered.
The pericardial fat was removed and the pericardium opened. Thereafter, the LAD was identified by following its course around the apex of the heart.
At the same time, the patient-side surgeon exposed the common femoral artery and vein of the left groin. For venous cannulation for cardiopulmonary bypass (CPB) we used a 25 F or 27 F Medtronic venous cannula. For arterial perfusion either a 21 F Remote Access Perfusion (ESTECH) or a 23 F Endoreturn (Heartport, Cardiovations) arterial cannula was used. Balloon endoocclusion of the ascending aorta was followed by administration of cardioplegic solution (St Thomas II cardioplegia mixed with blood). The operations were carried out in mild hypothermia (32–34 °C). The LAD was exposed and incised with an endoscopic knife. The LIMA to LAD anastomosis was sutured with 7/0 Pronova running suture. Thereafter, the endoaortic balloon was deflated and the heart was reperfused. If necessary, percutaneous defibrillation was performed. After rewarming and reperfusion the patient was weaned from the CPB. The cannulae were removed and the femoral vessels were reconstructed.
A video of an AH-TECAB LIMA-LAD procedure is available on the website of the minimally invasive robotic association (MIRA) – http://www.miraweb.org/video.htm
2.2. Statistics
Data were prospectively collected and analyzed retrospectively using SPSS 15.0 for Windows. Categorical variables are shown as numbers and percentages, continuous variables as median and range. For bivariate correlation of continuous variables with the BMI we used the Spearman test. For comparision of BMI levels of patients with and without adverse events we used the Mann–Whitney U-test. P<0.05 were regarded as statistically significant.
|
3. Results
|
|---|
Patients (n=127) [101 male, 26 female, median age 59 (31–77) years], undergoing AH-TECAB procedures were enrolled. The BMI was 26 (19–38). In detail, 27 patients were normal weight (BMI: 25 kg/m2), 67 patients were overweight (BMI: 25.1–30 kg/m2), 29 patients were obese (BMI: 30.1–33.9 kg/m2) and four patients were morbidly obese (BMI: 34 kg/m2).
The Heartport/CardiovationsTM (n=44) or the ESTECH-RAPTM system (n=83) were used for AH-TECAB procedure with remote access perfusion and aortic endoocclusion. In the Spearman-rank correlation we could not find any significant correlation between median BMI and (1) LIMA takedown-time (R=0.02; P=n.s.), (2) lipectomy and pericardiotomy time (R=0.042; P=n.s.), (3) total operative time (R=–0.083; P=n.s.), (4) CPB time (R=–0.012; P= n.s.), (5) aortic endoocclusion time (R=–0.055; P=n.s.), (6) mechanical ventilation time (R=0.001; P=n.s.) (7) length of ICU-stay (R=0.04; P=n.s.), or (8) length of hospital stay (R=–0.103; P=n.s.) (Table 2, Figs. 1–4 ).
View larger version (19K):
[in this window]
[in a new window]
|
Fig. 3. Correlation of TECAB time (min) with the BMI (TECAB time is time from portplacement to skin closure).
|
|
When comparing the mean BMI levels of patients with and without adverse events we could not find different BMI levels in patients with and without surgical problems. The conversion rate to sternotomy and the on-table revision rate (n=5) were independent of the patient's BMI. Patients with atrial fibrillation (AF) in the postoperative course had similar BMI levels than those who were free from AF (Table 3). General outcome of our series of patients undergoing AH-TECAB procedure are listed in Table 4.
View this table:
[in this window]
[in a new window]
|
Table 4 Showing general outcome of all 127 patients undergoing TECAB (total endoscopic coronary artery bypass) procedure
|
|
|
4. Discussion
|
|---|
In overweight and obese patients undergoing TECAB, we could not show increased operative times or increased rates of intra- or postoperative complications when compared with normal weight patients.
Looking at the results of endoscopic and robotic surgery of other surgical fields totally endoscopic coronary artery bypass surgery seems to be highly attractive.
Laparoscopic cholecystectomy (LCHE) is the most established endoscopic procedure in surgery. Gatsoulis et al. investigated the outcome of obese patients after LCHE in comparison to normal weight patients: this study showed that operative times in obese patients are slightly increased in patients with higher BMI [9]. Nevertheless, mortality, perioperative complication rate, length of hospitalization and conversion rate showed no significant difference between obese and non-obese patients.
In patients undergoing robotic endoscopic prostatectomy Herman et al. previously found operative time to increase significantly when BMI exceeded 30 kg/m2 [10]. In this series obese patients also had significantly greater blood loss whereas the perioperative clinical outcome was comparable to normal weight patient. Similarly, Castle et al. reported longer operation times in obese patients whilst the perioperative complication rate was not increased [11].
Previously, Vassiliades et al. reported in obese patients (e.g. BMI30) undergoing CABG, performed through minithoracotomy, an increased LIMA takedown-time and an overall operation time as compared to normal weight patients [12]. In detail, LIMA-harvest time and overall operation time started to increase at a BMI level of 30 kg/m2 and increased even more pronounced when the BMI exceeded 34 kg/m2 [12].
In contrast, the present AH-TECAB study found LIMA harvest time and overall operation times in obese patients comparable to that of normal weight patients.
We had expected that in robotic TECAB at least the procedure part of pericardial fat pad removal and opening of the pericardium would take more time in obese patients. For us, it was rather surprising that there was no significant correlation between the removal of the pericardial fat and the BMI. This might be due to the fact that not every overweight patient inevitably has more pericardial fat. As one can take from Fig. 3, we also had rather long times for the fat removal in some patients with completely normal BMI. Different overall patterns of fat distribution in the patients' bodies may be another explanation for this.
One can speculate that patients benefit the most from the TECAB procedure when they are at risk for postoperative deep wound complications. Sternotomy approaches are associated with higher rates of deep and superficial wound healing problems in obese patients [2, 13] and with longer times on CPB [2]. Birkmeyer et al. showed that obese patient are 1.96-fold, severely obese patients even 2.32-fold more likely to develop sternal wound infections than non-obese patients [2]. In the same study, it has been shown that already moderate obese patients (BMI30 kg/m2) have longer CPB times and are more likely to develop deep and superficial wound healing problems. Therefore, it seems reasonable to hypothesize that especially obese patients might benefit most from a total endoscopic approach. No deep thoracic wound infection occurred in our series.
The main limitation of our study is that the number of morbidly obese patients enrolled was rather low (e.g. n=4), which of course limits statements on perioperative complications and outcome in these patients undergoing AH-TECAB.
In conclusion, we showed that overweight, obese but also morbidly obese patients, who undergo AH-TECAB procedures, can be operated on with acceptable operative times. Their intra- and postoperative risk is comparable to that of normal weight patients.
|
References
|
|---|
- Flegal KM, Carroll MD, Kuczmarski RJ, Johnson CL. Overweight and obesity in the United States: prevalence and trends 1960–1994. Int J Obes Relat Metab Disord 1998;22:39–47.[CrossRef][Medline]
- Birkmeyer NJ, Charlesworth DC, Hernandez F, Leavitt BJ, Marrin CA, Morton JR, Olmstead EM, O'Connor GT. Obesity and risk of adverse outcomes associated with coronary artery bypass surgery. Northern New England Cardiovascular Disease Study Group. Circulation 1998;97:1689–1694.[Abstract/Free Full Text]
- Prabhakar G, Haan CK, Peterson ED, Coombs LP, Cruzzavala JL, Murray GF. The risks of moderate and extreme obesity for coronary artery bypass grafting outcomes: a study from the Society of Thoracic Surgeons' database. Ann Thorac Surg 2002;74:1125–1130; discussion 1130–1131.[Abstract/Free Full Text]
- Kuduvalli M, Grayson AD, Oo AY, Fabri BM, Rashid A. The effect of obesity on mid-term survival following coronary artery bypass surgery. Eur J Cardiothorac Surg 2003;23:368–373.[Abstract/Free Full Text]
- Bonatti J, Schachner T, Bernecker O, Chevtchik O, Bonaros N, Ott H, Friedrich G, Weidinger F, Laufer G. Robotic totally endoscopic coronary artery bypass: program development and learning curve issues. J Thorac Cardiovasc Surg 2004;127:504–510.[Abstract/Free Full Text]
- Bonatti J, Schachner T, Bonaros N, Oehlinger A, Danzmayr M, Rutzler E, Bernecker O, Margreiter J, Velik-Salchner C, Friedrich G, Jonetzko P, Laufer G. Ongoing procedure development in robotically assisted totally endoscopic coronary artery bypass grafting (TECAB). Heart Surg Forum 2005;8:E287–E291.[CrossRef][Medline]
- Oehlinger A, Bonaros N, Schachner T, Ruetzler E, Friedrich G, Laufer G, Bonatti J. Robotic endoscopic left internal mammary artery harvesting: what have we learned after 100 cases? Ann Thorac Surg 2007;83:1030–1034.[Abstract/Free Full Text]
- Bonatti J, Schachner T, Bonaros N, Ohlinger A, Danzmayr M, Jonetzko P, Friedrich G, Kolbitsch C, Mair P, Laufer G. Technical challenges in totally endoscopic robotic coronary artery bypass grafting. J Thorac Cardiovasc Surg 2006;131:146–153.[Abstract/Free Full Text]
- Gatsoulis N, Koulas S, Kiparos G, Tzafestas N, Pangratis K, Pandis K, Mavrakis G. Laparoscopic cholecystectomy in obese and nonobese patients. Obes Surg 1999;9:459–461.[CrossRef][Medline]
- Herman MP, Raman JD, Dong S, Samadi D, Scherr DS. Increasing body mass index negatively impacts outcomes following robotic radical prostatectomy. J Soc Laparoendosc Surg 2007;11:438–442.[Medline]
- Castle EP, Atug F, Woods M, Thomas R, Davis R. Impact of body mass index on outcomes after robot assisted radical prostatectomy. World J Urol 2008;26:91–95.[CrossRef][Medline]
- Vassiliades TA Jr, Nielsen JL, Lonquist JL. Effects of obesity on outcomes in endoscopically assisted coronary artery bypass operations. Heart Surg Forum 2003;6:99–101.[Medline]
- Nagachinta T, Stephens M, Reitz B, Polk BF. Risk factors for surgical-wound infection following cardiac surgery. J Infect Dis 1987;156:967–973.[Medline]
|
|
Top
Abstract
1. Background
