Editorials

Is Off-Pump Cardiac Surgery Better for the Brain?

Brain damage is a serious complication of cardiac anesthesia. The purpose of this study was to detect brain damage at different surgical stages during coronary artery bypass graft with or without cardiopulmonary bypass.

We conducted a prospective, longitudinal study to evaluate serum S-100 β protein, an early marker of brain injury, in patients electively undergoing off-pump (n = 30) or traditional coronary artery bypass graft (n = 60). Blood was sampled immediately before anesthesia, before and after cardiopulmonary bypass, and on the day after surgery.

Serum S-100 β protein was lowest immediately before induction of anesthesia and significantly increased before and after cardiopulmonary bypass, then declined by the first postoperative day in both groups. Peak values were highest in the traditional group directly after coronary artery bypass graft. On the day after surgery, S-100 β protein levels were similar between groups, but were higher than baseline within each group. Significant increase in serum S-100 β protein was also observed even before cardiopulmonary bypass in cardiopulmonary bypass patients, or before manipulation of the heart and aorta in off-pump patients. These reflect the possibility that brain damage may occur before major manipulation (cardiopulmonary bypass or manipulating heart and aorta). Moreover, S-100 β levels did not return to normal on the day after the operation.

This prospective study has shown that serum S-100 β protein was not only higher than baseline both after cardiopulmonary bypass and on the day after surgery in both groups of patients but it was also significantly increased before cardiopulmonary bypass or manipulation of the heart or aorta. These findings may have implications for anesthesiologic care during the total course of cardiac surgery.

Whether the clinical outcome of off-pump coronary artery bypass graft (OPCABG) surgery is superior to on-pump coronary artery bypass graft (CABG) surgery is still a matter of debate. However with the considerable reduction of mortality associated with CABG surgery in recent years, more subtle outcome indicators such as quality of life (QOL) become more important. The aim of this study was to compare midterm QOL after OPCABG with that after CABG procedures and with an age- and sex-matched standard population.

Quality of life was assessed using the Short-Form 36 Health Survey Questionnaire for 504 consecutive patients after CABG (n = 438) and OPCABG (n = 66) operated on between June 1999 and November 2000 at our institution.

Except for single-vessel disease, which was more frequent in OPCABG compared with CABG procedures (13.6% versus 6.8%; p <0.01), the preoperative variables were similar. Median EuroSCORE (European System for Cardiac Operative Risk Evaluation) was 3.2 ± 1.3 in the CABG group compared with 3.0 ± 0.8 in the OPCABG group (p = not significant). After a mean follow-up of 10.8 ± 0.5 months physical role function (73.5 ± 38.3 versus 45.3 ± 41.6; p <0.01) and emotional role function (75.3 ± 40.3 versus 61.0 ± 43.9; p <0.01) were significantly better in OPCABG than in CABG patients. Compared with a standard population, OPCABG patients were significantly impaired in emotional role function and CABG patients in physical and emotional role function.

Midterm QOL after myocardial revascularization is fairly well preserved compared with an age- and sex-matched standard population and is superior after OPCABG compared with CABG. Whether this is only due to avoidance of cardiopulmonary bypass remains to be elucidated.

La incidencia de lesiones neurológicas graves tras la cirugía cardíaca se ha establecido en un 6,1%: un 3,1% de lesiones focales y un 3% de lesiones difusas. Parece que su causa es multifactorial. Se ha conjeturado que ciertos factores preoperatorios, como la presencia de hipertensión, diabetes insulinodependiente, la edad avanzada y la presencia de enfermedad cerebrovascular previa, se asociarían con la aparición de estas lesiones. Sin embargo, también se relaciona con factores intraoperatorios: el tipo de manejo ácido- base, el flujo sistémico durante la circulación extracorpórea (CEC), la presión de perfusión cerebral, el hematócrito durante la CEC, la duración de ésta, el control de las glucemias y la liberación de mediadores inflamatorios.

Aunque se han utilizado diversos métodos de protección neurológica durante la CEC, ninguno ha demostrado evitar completamente la aparición de estas lesiones. Habitualmente se emplea la hipotermia, la prevención del desprendimiento de placas de ateroma con ecocardiografía, la prevención de microembolismos con filtros y la hemodilución. últimamente se han ensayado diversos fármacos con resultados dispares

The incidence of severe neurological injury after cardiac surgery is 6.1%: focal lesions account for 3.1% and diffuse lesions for 3%. The cause of these lesions is multifactorial. It has been speculated that certain preoperative factors such as hypertension, insulin-dependent diabetes, advanced age and previous cardiovascular disease could be associated with the development of neurological injury. However, intraoperative factors also play a role: the type of acid-base management, systemic flow during extracorporeal circulation (ECC), cerebral perfusion pressure, hematocrit during ECC, duration of ECC, glycemia regulation and release of inflammatory mediators.

Although several methods of neurological protection have been used during ECC, none of them completely prevents neurological injury. Usually, the methods employed are hypothermia, prevention of the release of atheroma plaques with echocardiography, prevention of microemboli with filters, and hemodilution. Several drugs have recently been tried with differing results.