| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Ann Thorac Surg 2001;72:S1022-S1025
© 2001 The Society of Thoracic Surgeons
a Departments of Surgery and Anesthesiology, University Hospitals of Cleveland, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
Address reprint requests to Dr Lee, Division of Cardiothoracic Surgery, University Hospitals of Cleveland, 11100 Euclid Ave, Cleveland, OH 44106
e-mail: jai.lee{at}uhhs.com
Presented at the Seventh Annual Cardiothoracic Techniques and Technologies Meeting 2001, New Orleans, LA, Jan 24–27, 2001.
 |
Abstract |
|---|
 TopFootnotes Abstract IntroductionMaterial and methodsResultsCommentReferences |
|---|
Methods. We compared outcomes among 187 consecutive patients undergoing OPCAB over a 12-month period by a single surgeon (J.H.L.). This study included 61 women and 126 men, representing 91% of all isolated CABG operations during the same time.
Results. The demographics were as follows: Women (n = 61) were older than men (n = 126) (67.5 versus 64.6 years; p = 0.05). They had a greater prevalence of congestive heart failure (28% versus 17%; p = 0.005), and were more frequently on intravenous nitroglycerin preoperatively (49% versus 32%; p = 0.05). Overall mortality was 1.6% (3 of 187). In-hospital complications were as follows: deaths 3.3% in women and 0.9% in men (p = 0.25); major bleeding 0% in women and 3.2% in men (p = 0.30); stroke 1.5% in women and 0% in men (p = NS). Mediastinitis or renal failure was not noted in either group. Extubation times (6.6 versus 6.1 hours; p = 0.001), surgical intensive care unit length of stay (43 hours versus 37 hours; p = 0.013), and postoperative length of stay (6.4 days versus 5.8 days; p = 0.014) were all significantly longer in women compared with men. When OPCAB women were compared with a matched cohort of women undergoing CABG, length of stay was similar, whereas OPCAB men realized a 13% reduction in length of stay compared with men undergoing conventional CABG (p = 0.002).
Conclusions. Women presenting for OPCAB are older and have greater comorbidities than men. The elimination of cardiopulmonary bypass did not improve the recovery time of women, a finding that was strikingly different from the effect seen in men. These compelling results suggest that biochemical, hormonal, or pharmacokinetic factors in women may neutralize the anticipated beneficial effect of avoiding cardiopulmonary bypass.
|
Introduction |
|---|
|
TopFootnotesAbstractIntroductionMaterial and methodsResultsCommentReferences |
|---|
The recent resurgence of off-pump coronary artery bypass (OPCAB) procedures has been fueled by the perception that the avoidance of cardiopulmonary bypass and its deleterious consequences could enhance the outcomes of coronary artery bypass grafting (CABG) operations. Despite the numerous studies documenting female gender-related risk factors associated with cardiac operations, the effect of gender on outcomes after OPCAB has not been elucidated. An analysis of 187 consecutive OPCAB procedures over a 12-month period was undertaken to determine if this gender difference is found in OPCAB.
|
Material and methods |
|---|
|
TopFootnotesAbstractIntroductionMaterial and methodsResultsCommentReferences |
|---|
Definitions
Operative mortality was defined as death occurring within 30 days of the operative procedure or during the same hospital stay. Perioperative myocardial infarction was defined by the presence of new Q waves in two or more contiguous leads on a standard 12-lead electrocardiogram. Preoperative renal insufficiency or failure was considered present if patients had a serum creatinine level higher than 2.0 mg/dL or were undergoing dialysis (peritoneal or hemodialysis). Postoperative stroke was defined as any new persistent postoperative neurologic deficit that was also confirmed with a positive head computed tomography scan or magnetic resonance imaging. Mediastinitis was defined as a sternal wound infection requiring a second surgical procedure for closure. Bleeding was defined by the need to reexplore the patient.
Statistical analysis
All data were prospectively collected on standardized forms and entered into a computerized database (Summit Medical, Inc, Minneapolis, MN). All data are expressed as mean ± standard deviation or as percentages, where appropriate. Clinical and operative differences between the two groups were tested for statistical significance by using t tests and confidence intervals for the difference of the two means.
Differences in percentages were tested using the 
2 test or Fisher exact test for small expected frequencies, as appropriate. Intubation times and length of stay data were analyzed using nonparametric Mann–Whitney tests because of the skewed nature of the data.
Surgical and anesthetic technique
The technique for OPCAB included a median sternotomy and left internal mammary artery harvesting while the radial arteries and saphenous veins were simultaneously harvested. Heparin was administered before division of the internal mammary artery, and a target activated clotting time of 300 seconds was maintained during the procedure. Ischemic preconditioning was not done routinely. Proximal occlusion was done using a silicone vascular loop (Quest Medical, Inc, Allen, TX) and distal snaring was not done. Shunts were occasionally used, and in situations of brisk back bleeding, a Flo-resistor (1.0 or 1.5 mm) (Medtronics, Inc, Minneapolis, MN) was found to be useful.
A humidified, sterile, carbon dioxide blower/mister (Medtronic, Inc, Minneapolis, MN) was used to clear the anastomoses of blood. A commercial mechanical stabilizer (Medtronic Octopus II system) was used during the anastomoses, and all distal anastomoses were sewn with a 7-0 nonabsorbable monofilament suture under direct vision.
For access to the posterior target vessels (circumflex and posterior descending artery) a pericardial-based sling retractor technique was used to position the heart and subsequent anastomoses carried out using stabilizers. No attempt was made to slow the heart rate with negative chronotropes.
Proximal anastomoses were sewn to a nondiseased aorta under partial occlusion clamp with 5-0 or 6-0 suture. We abandoned any manipulation of the aorta if atherosclerotic plaque was noted by either palpation or transesophageal echocardiogram, which was used as clinically indicated, usually at the discretion of the anesthesiologist. In certain situations in which arteries were providing important collateral flow, proximal anastomoses were completed before distal anastomoses in order to establish perfusion to ischemic target areas rapidly.
Anesthetic agents were selected with the intent of facilitating early extubation, whenever possible. This objective can be accomplished easily with a balanced anesthetic technique using short-acting intravenous agents (fentanyl, midazolam) and a volatile inhalational agent (isoflurane). Although use of regional techniques has been described for OPCAB procedures (intrathecal opioids, epidural regional anesthesia), this approach was not used. Total fentanyl doses were 10 to 25 µg/kg and total midazolam doses were less than 0.1 mg/kg. Overall narcotic and benzodiazepine doses did not differ between groups because of the routine use of inhalational agents. In other words, a fast-track protocol was applied in all cases.
|
Results |
|---|
|
TopFootnotesAbstractIntroductionMaterial and methodsResultsCommentReferences |
|---|
|
The overall operative mortality was 1.6% (3 of 187 patients.) Two deaths occurred among female patients. One patient died from ventricular arrhythmias, and another from complications of a stroke. Sudden cardiac death was responsible for the death in the male patient. Autopsies of patients with cardiac deaths revealed patent grafts. The incidence of significant complications among the two groups is shown in Table 2. A benefit observed in the OPCAB group was an exceptionally low incidence of serious perioperative morbidity. Overall incidence of stroke was 0.5%. Of note, we did not encounter any instance of renal failure requiring dialysis or deep sternal infection in either men or women undergoing OPCAB. Despite a higher prevalence of preoperative comorbid conditions among women, the incidence of serious postoperative morbidity was similar among men and women.
|
|
|
|
Comment |
|---|
|
TopFootnotesAbstractIntroductionMaterial and methodsResultsCommentReferences |
|---|
Although gender has been demonstrated in many studies to be a prognostic determinant of outcome in coronary revascularization procedures, the physiologic reason for this difference remains elusive. Differences in outcome have been related to several factors, including vessel diameter [3] and body size [4]. In one study, women were found to have smaller coronary arteries, even after controlling for differences in body size [5].
Loop and colleagues [1] suggested that this finding might be related to the smaller body surface area observed in women, and to greater technical difficulty in grafting smaller diameter coronary vessels. Khan and associates [6] attributed outcome differences to referral bias and older age at presentation for women. In the CASS study, the higher mortality seen in the female population (4.5% in women versus 1.9% in men) was believed to be due to gender-related variables (age, unstable angina, congestive heart failure, left main coronary disease, and number of grafted vessels) [7]. Other studies have demonstrated that even after adjusting for preoperative comorbid variables, female gender remains an independent risk factor for mortality after CABG operation [8].
The recent interest in OPCAB and its reported benefits raised the question as to whether elimination of the extracorporeal circuit would improve outcomes in women undergoing CABG operation. It is well known that cardiopulmonary bypass is associated with many adverse systemic effects that can lead to increased morbidity, particularly in higher-risk patient populations. Some of the reported benefits of avoiding cardiopulmonary bypass include improved neurologic outcome, better preservation of renal function, reduced transfusion requirements, decreased activation of the inflammatory response, and cost savings.
In the present study, women had longer intubation times, intensive care unit stay, and postoperative length of stay. A number of factors have been shown to affect intubation times after cardiac operation, including age, female gender, unstable angina, postoperative intraaortic balloon requirement, transfusion, use of preoperative diuretics, duration of cardiopulmonary bypass, temperature, hemodynamic instability, and renal insufficiency [9]. The longer intubation times seen in women in our study could not be explained by preexisting pulmonary disease, because the incidence was not significantly different between groups. An important point to consider is intubation time as a function of process of care, because patients admitted to the intensive care unit earlier in the day are more likely to be extubated early. It seems unlikely that this alone would have affected the gender differences seen in this study, since case scheduling is not gender based.
Hypothermia could not be used to explain the observed differences in intubation times, because patients undergoing OPCAB at our institution are aggressively maintained normothermic. Active measures including forced-air heating devices, warmed intravenous fluids, heating mattresses, and raising the ambient temperature are routine practices.
An increased sensitivity to anesthetic agents might explain the prolonged intubation times seen in women. In animals and humans, pharmacokinetic and pharmacodynamic gender differences have been noted for various drugs. Whether these observations translate into prolonged intubation times remains speculative though.
If female gender alone is truly an independent risk factor for increased postoperative intubation and length of stay, the question still remains how gender differences lead to such a notable discrepancy. Hormonal and biochemical effects may be responsible. Nussmeier and colleagues [10] demonstrated improved survival with hormone replacement therapy in postmenopausal women undergoing CABG operations, although the reasons for this finding were unclear.
In this study, major morbidity as depicted in Table 2 was not significantly different between groups, and could therefore not explain the overall increased LOS observed in women. Contrary to our expectations, the elimination of cardiopulmonary bypass did not improve the recovery time of female patients, whereas a substantial benefit was realized among men.
In conclusion, women represent a complex group of patients. Their physiologic response to cardiac disease, operation, and anesthesia raises many questions and concerns, including what is the best way to approach this patient population. Gender-specific variables should be an area of future study if we are to improve outcomes in women undergoing cardiac operations. There may in fact be subsets of women who gain a greater benefit from off-pump coronary revascularization versus conventional CABG operation. Further investigation will help to elucidate the answer to this and other related questions.
|
Footnotes |
|---|
|
TopFootnotesAbstractIntroductionMaterial and methodsResultsCommentReferences |
|---|
|
References |
|---|
|
TopFootnotesAbstractIntroductionMaterial and methodsResultsCommentReferences |
|---|
This article has been cited by other articles:
|
|
 |
|
  A. Parolari, L. Dainese, M. Naliato, G. Polvani, C. Loardi, M. Trezzi, M. Fusari, C. Beverini, E. Tremoli, P. Biglioli, et al. Do Women Currently Receive the Same Standard of Care in Coronary Artery Bypass Graft Procedures as Men? A Propensity Analysis Ann. Thorac. Surg., March 1, 2008; 85(3): 885 - 890. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
F. H. Edwards, V. A. Ferraris, D. M. Shahian, E. Peterson, A. P. Furnary, C. K. Haan, and C. R. Bridges Gender-Specific Practice Guidelines for Coronary Artery Bypass Surgery: Perioperative Management Ann. Thorac. Surg., June 1, 2005; 79(6): 2189 - 2194. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Bucerius, J. F. Gummert, T. Walther, M. A. Borger, N. Doll, V. Falk, and F. W. Mohr Impact of Off-Pump Coronary Bypass Grafting on the Prevalence of Adverse Perioperative Outcome in Women Undergoing Coronary Artery Bypass Grafting Surgery Ann. Thorac. Surg., March 1, 2005; 79(3): 807 - 812. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. A. Fox and N. A. Nussmeier Does Gender Influence the Likelihood or Types of Complications Following Cardiac Surgery? Seminars in Cardiothoracic and Vascular Anesthesia, December 1, 2004; 8(4): 283 - 295. [Abstract] [PDF]
|
|
|
|
|
|
T. Athanasiou, S. Al-Ruzzeh, R. D. Stanbridge, R. P. Casula, B. E. Glenville, and M. Amrani Is the female gender an independent predictor of adverse outcome after off-pump coronary artery bypass grafting? Ann. Thorac. Surg., April 1, 2003; 75(4): 1153 - 1160. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| ANN THORAC SURG | ASIAN CARDIOVASC THORAC ANN | EUR J CARDIOTHORAC SURG |
| J THORAC CARDIOVASC SURG | ICVTS | ALL CTSNet JOURNALS |
