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Eur J Cardiothorac Surg 2003;23:657-664
© 2003 Elsevier Science NL
a Department of Cardiac Surgery, University of Brescia Medical School, Brescia, Italy
b Department of Cardiology, University of Brescia Medical School, Brescia, Italy
Received 25 September 2002; received in revised form 20 January 2003; accepted 3 February 2003.
* Corresponding author. UDA Cardiochirurgia, Spedali Civili di Brescia, P.le Spedali Civili, 1, 25123 Brescia, Italy. Tel.: +39-30-399-6401; fax: +39-30-399-6096
e-mail: munerett{at}master.cci.unibs.it
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Abstract |
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 Top Abstract 1. Introduction2. Materials and methods3. Results4. DiscussionAppendix A. Conference...References |
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Key Words: CABG surgery • Arterial conduits • Composite grafts • Elderly patients
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1. Introduction |
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TopAbstract1. Introduction2. Materials and methods3. Results4. DiscussionAppendix A. Conference...References |
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An increasing number of authors reported that total arterial revascularization may improve the clinical outcome of patients when compared to conventional CABG surgery (LITA on LAD plus additional saphenous vein grafts (SVG)) [4,6]. However, the advantages of total arterial grafting in the elderly have not been demonstrated yet. The aim of the present study was to evaluate at short and mid term the safety and usefulness of total arterial revascularization with composite grafts in patients aging over 70 years.
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2. Materials and methods |
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TopAbstract1. Introduction2. Materials and methods3. Results4. DiscussionAppendix A. Conference...References |
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2.2. Surgical procedure and post-operative management
Following median sternotomy, the ITAs were harvested as pedicled conduits; side branches were extensively clipped and electrocautery was avoided in order to prevent any thermal injury. The first intercostal branch and the distal bifurcation were systematically preserved. After systemic heparinization, both the ITAs were divided distally and a solution of papaverine hydrochloride (200 mg of papaverine in 100 ml of normal saline) was applied topically. In Group 1 the harvesting of both ITAs was avoided in patients with insulin-dependent diabetes mellitus with clinical evidence of microangiopathies, obesity (BMI>30) and chronic obstructive lung disease associated with severe emphysema and/or long standing steroid treatment.
In patients scheduled for radial artery (RA) harvesting, a pre-operative evaluation of the non-dominant arm (Allen test, oximetric plethysmography curve of the thumb during RA occlusion) was performed in order to assess the adequacy of collateral blood flow from the ulnar artery. In order to minimize RA wall damage and to prevent the risk of spasm, RA was harvested preserving satellite veins and surrounding connective tissue. After heparinization, the RA was divided distally, papaverine hydrochloride was injected intraluminally and a titanium clip was applied on the distal end. The RA was maintained in situ until the related coronary had to be performed in order to avoid arterial damage and spasm due to unnecessary storage.
Composite arterial grafts were realized by means of an end-to-side anastomosis (8/0 polypropylene running suture) of the RITA and/or RA in a Y/T graft fashion to the in situ LITA, always prior to cardiopulmonary bypass (CPB). Three different configurations were used to realize the composite grafts.
2.2.1. Type 1 configuration
The RITA is anastomosed as Y graft to the in situ LITA while the RA is used as a free graft for the right coronary system. This configuration was used in case of dominant, not occluded right coronary artery to avoid in such cases a composite graft totally dependent from the proximal LITA inflow (Fig. 1a
).
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2.2.3. Type 3 configuration
Two segments of RA or/plus RITA are anastomosed end-to-side to the LITA, in order to obtain a double Y graft. This geometry was used when planned configuration type 1 or 2 could not be performed because of atheromatic lesions of the ascending aorta or unfavorable anatomy of the postero-lateral coronary vessels (Fig. 1c).
Cardiopulmonary bypass was instituted with a double-stage right atrial cannula for the venous line and cannulation of the ascending aorta for the arterial line, at a flow of 2.5 l/min/m2, maintaining a mean arterial blood pressure greater than 50 mmHg under mild hypothermia (33°C). Myocardial protection was achieved with intermittent antegrade and retrograde cold blood cardioplegia. Distal anastomoses were performed end-to-side or side-to-side (diamond-shaped configuration) with 8/0 polypropylene running suture. Proximal anastomoses were performed during rewarming under single aortic side clamping with a 6/0 (for saphenous vein grafts) or a 7/0 (for arterial conduits) polypropylene running suture. We avoided the use of the RITA as a free graft with proximal anastomosis on the ascending aorta. When the RA was used as a free graft, the proximal anastomosis was performed in most cases on a saphenous vein patch seamed on the ascending aorta.
In patients receiving RA grafts, Diltiazem was given orally the day before operation (60 mg every 8 h). During the operation, we administered an intravenous infusion of Diltiazem (mean dose: 0.5–1.5 µg/kg/min) which was continued for the first 48 h after surgery. Thereafter Diltiazem (120 mg per day) was administered orally for at least 6 months. After surgery, patients were managed in the intensive care unit (ICU) according to the standard unit protocol; water mattress rewarming was used until a nasopharyngeal temperature of 37°C was reached.
2.3. Patient follow-up and data analysis
End-points of this study were: early post-operative complications, recurrence of angina, graft occlusion and death. Patients were followed up at 2, 6 and 12 months; outpatient information were collected from patients' cardiologist and home physicians and by telephone interview.
Comparison of pre-operative and post-operative variables between the groups were analyzed using the Fisher exact test and the 
2 test for discrete variables and the unpaired t-test and the Mann–Whitney test for continuous variables; values for continuous variables were expressed as mean±standard deviation. A P-value less than 0.05 was considered to be significant.
Multivariate analysis and survival curves (Kaplan–Meier) were calculated using the StatSoft (Version 5.1, 1997 Edition, StatSoft Italia S.r.l.). Multivariate analysis was carried out using the Cox regression model for the time-dependent variables (recurrence of angina, myocardial infarction) and the multivariate logistic regression for time-independent variable (graft occlusion).
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3. Results |
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TopAbstract1. Introduction2. Materials and methods3. Results4. DiscussionAppendix A. Conference...References |
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3.2. Perioperative data
A total of 423 anastomoses were performed in 188 patients (G1: 206 vs. G2: 217). The mean number of anastomoses was similar between the groups (G1: 2.19±0.6 vs. G2: 2.31±0.3). In G1 composite arterial grafts configurations were as follows: type 2 configuration was used in the majority of patients (72%) while type 1 and 3 configurations were used in 8.5 and 19% of patients, respectively. The use of type 1 configuration, which includes the free graft anastomosis of the RA on the ascending aorta, was restricted to few cases without any atherosclerotic involvement of the ascending aorta.
Intraoperative data are shown in Table 3. There were no differences in terms of aortic cross-clamping time while cardiopulmonary bypass time was higher in G2 (G1: 60±17 min vs. G2: 84±39 min) reflecting the additional time required to perform SVGs proximal anastomoses.
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Cerebro-vascular complications occurred in one patient in G1 (type 1 configuration) and in five patients in G2. All those patients underwent ascending aorta manipulation for proximal graft anastomosis. In addition to the listed complications (Table 3), eight patients (8.5%) in G2 had leg wound complications related to saphenous vein graft harvesting; among them, the incidence of diabetes was particularly high (75%). The incidence of blood transfusion was quite high in the study population without any difference between the groups (G1: 64% vs. G2: 61%, P=0.44).
3.3. Follow-up and late results
All the hospital survivors of G1 (89 pts) and G2 (90 pts) were evaluated by means of medical interview, clinical examination and cycloergometric test at 2, 6 and 12 months postoperatively. Mean duration of follow-up was 12±4 months without differences between the groups. Coronary angiography was carried out systematically in all patients with symptoms or with a positive or doubtful stress test (G1: two pts vs. G2: 11 pts). In addition, angiographic evaluation was carried out at random in 47 patients of G1 (50%) and 36 patients of G2 (38%). At the follow-up, the incidence of angina, percutaneous transluminal coronary angioplasty (PTCA) reintervention and graft occlusion were considerably lower in patients receiving total arterial revascularization (G1) (Table 4). Angiography showed three grafts occluded in G1 (one LITA to LAD and two RAs on the circumflex system) and 17 saphenous vein grafts occluded in G2 (10 SVGs on the right coronary system and seven SVGs on the circumflex system). The incidence of late death was comparable between the groups, while myocardial infarction was higher in G2 (G1: zero pts vs. G2: five pts) and near to reach statistical value (P=0.07). At 18 months the fraction of patients free from any recurrence of angina and/or myocardial infarction were considerably higher in G1 (Fig. 2A
). When the freedom from angina/myocardial infarction was analyzed with respect to the presence/absence of diabetes, the negative impact of diabetes on the mid-term clinical outcome was clearly evident especially in patients receiving saphenous vein grafts (Fig. 2B). The presence of hyperlipidemia also negatively affected the outcome of patients receiving SVGs, who showed an important worsening of the freedom from angina/myocardial infarction curve (Fig. 2C).
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4. Discussion |
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TopAbstract1. Introduction2. Materials and methods3. Results4. DiscussionAppendix A. Conference...References |
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This cohort of patients may represent in the near future the largest fraction of the population undergoing CABG surgery, at least in the developed countries. Coronary surgery in elderly has been associated with increased perioperative morbidity and mortality when compared to younger populations [14–16]. The higher operative risk in elderly seems to be not solely due to the aging process but mainly related to concomitant medical diseases and comorbidities [2].
In addition, previous studies demonstrated that elderly patients referred for CABG had more frequently disabling and unstable cardiac symptoms, compromised left ventricular function and more advanced coronary disease than younger patients [17–19]. In an attempt to reduce the surgical invasiveness and risk in elderly patients, many surgeons have been reluctant to use arterial grafts, even the LITA to LAD, preferring an extensive use of the saphenous vein grafts.
Conversely, Morris et al. [5] reported in 1996 that the use of LITA on LAD in octogenarians clearly improved mid- and long-term outcome when compared to saphenous vein grafts, suggesting that arterial grafts may have a positive impact on the outcome even in very old patients.
An insight in this controversial issue came from recent reports which showed that operative morbidity and mortality of coronary surgery in elderly had steadily declined during the last few years as a result of advances in surgical and medical care [2,20].
Moreover, other recent studies focused on the use of multiple arterial grafts, demonstrating that arterial revascularization improved the outcome of patients undergoing CABG surgery, regardless the type of the arterial conduit used [21,22].
As a logical consequence of the previous observations, the clinical benefits of arterial revascularization may be extended to the elderly population without any increase in operative morbidity and mortality. Our study was designed in order to evaluate the safety and usefulness of total arterial revascularization in comparison with the conventional technique (LITA on LAD plus additional saphenous vein grafts).
In an attempt to avoid the risk of selection bias and to allow comparison of treatment strategies of equal patients subsets, this study was designed as a prospective randomized comparison and patients entering the study were almost consecutive and unselected. Left ventricular ejection fraction less than 25%, emergency operation, single vessel disease and patients with Euroscore >10 were the only exclusion criteria. High risk patients were excluded in order to avoid that their unpredictable distribution could affect the reliability of the study. Our study indicates that elderly patients receiving total arterial revascularization with composite grafts (G1) do not have any increase in morbidity and mortality when compared to the conventional CABG group (G2).
The use of arterial grafts did not prolong the aortic cross-clamping time; conversely, the mean duration of cardiopulmonary bypass was considerably higher in patients receiving saphenous vein grafts as a result of the additional time required for proximal anastomoses. Both groups showed near to identical hospital mortality (G1: 5.3% vs. G2: 4.2%, P=NS), which was lower than the predicted (Euroscore) and that reported in literature for comparable patients subset [2,14]. The causes of death, similar between the groups, were mainly related to prolonged ventilatory support caused by respiratory insufficiency and cerebro-vascular accidents which led to sepsis and multiple organ failure.
The use of full arterial revascularization in elderly did not increase post-operative complications: in particular, the rate of prolonged intubation, perioperative myocardial infarction, bleeding and sternal dehiscence was comparable between the groups.
Cerebro-vascular complications occurred in five patients receiving SVGs (G2) and only in one patient of G1: the difference did not reach statistical value but we believe that it may become significant in a larger cohort of patients.
The use of arterial revascularization with composite grafts (G1) was clearly associated with a better clinical outcome when compared with conventional coronary surgery: at a mean follow-up of 12±4 months patients in G1 had a significant lower incidence of angina recurrence, graft occlusion and PTCA reinterventions. As a result, patients undergoing arterial revascularization exhibited a better clinical outcome in terms of freedom from angina and myocardial infarction (Kaplan–Meier).
Our study also evaluates the impact of associated medical diseases on the outcome of elderly patients. Freedom from angina and myocardial infarction was lower in patients with diabetes and hyperlipidemia receiving saphenous vein grafts. Multivariate logistic stepwise regression analysis identified diabetes, saphenous vein grafts and hyperlipidemia as independent predictors for graft occlusion. The same variables were also found to be incremental risk factors for angina recurrence and myocardial infarction with the Cox regression model: the probability to develop new onset of myocardial ischemia was four and six times higher in patients with saphenous vein grafts and diabetes, respectively. At any point of the data analysis, there was evidence that patients receiving saphenous vein grafts had an higher incidence of late cardiac events when compared with patients receiving arterial grafts; in addition, the poor clinical outcome of saphenous vein grafts patients was worsened by the presence of diabetes and hyperlipidemia.
This study has some shortcomings mainly related to the small number of patients analyzed and to the fact that it was a single institution study. The latter influenced the characteristics of the study population which differed from that reported in literature for the very high prevalence of diabetes. In addition, a single institutional study carried out by few surgeons may account for additional bias related to surgical techniques, individual surgical skill and institutional quality of care.
In conclusion, this study suggests that TAMR in elderly is a safe procedure that may be performed without any increase in hospital morbidity and mortality. Technical pitfalls related to the use of arterial grafts may be overcome by using specific configurations of composite arterial conduits. Patients receiving arterial grafts showed a superior clinical outcome with a lower incidence of angina recurrence, myocardial infarction and graft occlusion, even at short term. The clinical benefits of total arterial revascularization were particularly evident in the presence of associated comorbidities very common in the elderly.
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Footnotes |
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Appendix A. Conference discussion |
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TopAbstract1. Introduction2. Materials and methods3. Results4. DiscussionAppendix A. Conference...References |
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And the second question is: sometimes the physiologically old patients have a very fragile thoracic wall. When I am facing this condition, I prefer not to use the second mammary artery because I fear that the thoracic wall could be damaged. What are you doing in this situation?
Dr Muneretto: Concerning the first question, obviously the ideal configuration of composite arterial grafts was planned before the operation. Actually the majority of patients approximately 70%, received the type 2 configuration, that means one mammary artery and radial artery in a single Y graft. Sometimes the anatomy of the coronary artery makes this choice a challenge, as, for example, in the case of an important right dominant coronary artery. In this case we preferred to avoid a single inlet flow from LITA and we usually plan a type 1 configuration with a free radial artery graft on the right side. In some of those patients, at the beginning of the aortic manipulation or at the intraoperative echocardiography, some lesions of ascending aorta were founded making it necessary to move other type of configuration avoiding aortic manipulation.
Finally, sometimes that we planned on type 2 configuration, that is based on sequential anastomosis of radial artery on postero-lateral Vessels the angle between the coronary vessel or the diameters of coronary vessel make the sequential anastomosis a challenge. In this case we just cut in two pieces the radial artery and we move to the third configuration, a double Y graft that may avoid any technical pitfalls.
Could you please remind me your second question, please?
Dr Dion: About the fragility of the thoracic wall in very old patients.
Dr Muneretto: Yes, of course we were very concerned about the risk of sternal complication in high risk patients. However, the majority of patients, as I told you before, received only LITA and RA grafts. Anyhow, in those in which we harvested mammary arteries there was no evidences of an increase of sternal complication. This means that we didn't pay any price for the arterial revascularization. On the contrary it is very interesting to note that in patients older than 75 years old the incidence of leg complications related to saphenous vein graft harvesting ranged between 8% and 12%.
Dr S. Ghosh (Coventry, United Kingdom): Harping on what Dr. Dion said, what's your result about the harvesting bilateral mammaries in diabetics? What is the incidence of your stand-alone infection?
Dr Muneretto: We tried to avoid the double mammary harvesting in these type of patients. Basically a great majority of those patients underwent type 2 configuration, in which both mammary artery or radial artery were used in Y graft for total revascularization.
Dr D. Taggart (Oxford, United Kingdom): The only other comment I would make, we very much support in our own practice a policy of total arterial revascularization. But I think equally important in this population, these are the ones who will gain most by doing it off pump. And I think in this population, if you can do them off pump, then that's where you get a very significant reduction in morbidity, and particularly in the area of stroke, by totally avoiding manipulation of the aorta.
Dr Muneretto: I completely agree with you about the importance of OPCAB surgery in the elderly. This study was carried out to evaluate safety and usefulness of arterial graft in elderly in comparison with saphenous vein graft and did not have the purpose to analyze the usefulness of OPCAB procedures.
However, we strongly support the use of OPCAB especially in elderly and we are currently performing 80–85% of our coronary cases off pumps.
The use of composite graft prove to be an easy and effective technique of total revascularization especially in off pump surgery in which it allows an optimal length and mobilization of conduits avoiding any aortic manipulation.
Dr H. Sons (Kassel, Germany): Were all the operations performed by one surgeon, or did the more experienced surgeon perform the arterial grafts and the vein grafts were done by the resident?
Dr Muneretto: The study was performed basically by two surgeons, one performing full arterial grafting and the other one performing the conventional procedures. Both surgeons had a very wide experience in coronary surgery.
Dr S. Bose (Calcutta, India): My question is that I noticed that for the dominant right coronary artery, you're trying to put in a radial artery directly. You're not extending the LITA Y up to the right coronary artery. What has been the experiences when you extended the right internal mammary artery up to a dominant right coronary artery?
Dr Muneretto: We didn't experience any inconvenience in the use of a single inlet composite arterial graft in patients with dominant right coronary artery. The decision to avoid the single inlet in such patients was simply taken for precautionary reasons.
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References |
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TopAbstract1. Introduction2. Materials and methods3. Results4. DiscussionAppendix A. Conference...References |
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