Adult heart surgery patients are increasingly older with varying degrees of preoperative ventricular failure. Patients routinely present with both systolic and diastolic ventricular dysfunction, ventricular remodeling, fluid retention, and pulmonary congestion. Additionally, even those patients with well-preserved preoperative ventricular function can deteriorate intraoperatively secondary to inadequate myocardial preservation, embolism, myocardial ischemia, protamine reactions, and other “catastrophic” events (e.g., anaphylaxis and aortic dissection). Of course, the overwhelming majority of patients experiencing intra-operative right or left ventricular failure can be treated with a combination of inotropes and/or inhaled pulmonary vasodilators. However, others lack sufficient ventricular function to provide adequate delivery of oxygenated blood to the tissues. Such patients readily develop kidney dysfunction, acidosis, and cardiogenic shock unless provided mechanical assistance to support or replace the heart’s pump function. This chapter reviews the anesthetic management of patients in need of intra-aortic balloon counterpulsation (IABP), ventricular assist devices (VADs), and heart transplantation (HT).
INTRA-AORTIC BALLOON COUNTERPULSATION AND THE HEART SURGERY PATIENT
IABP counterpulsation is employed to assist the failing heart (Video 11–1). It is not a substitute for a beating ventricle and as such does not replace the function of the ventricle it is assisting. IABPs are generally introduced via the femoral artery into the thoracic aorta and positioned distal to the takeoff of the left subclavian artery. The IABP inflates with helium during diastole and deflates during systole. Thus, it creates a counterpulsation to the pulsation generated by the native heart. By inflating during diastole at the point of aortic valve closure, the IABP augments diastolic blood pressure and thus improves coronary artery perfusion pressure.
Video 11–1: Intra-Aortic Balloon Pump: LAX View
CPP = Diastolic blood pressure (DBP) − Left ventricular end-diastolic pressure (LVEDP)
During systole, the IABP deflates reducing the afterload against which the heart must eject, thereby potentially improving forward blood flow.
The cardiac anesthesiologist is likely to encounter the IABP in several situations:
Many patients presenting with myocardial ischemia refractory to medical or percutaneous interventions are provided an IABP in the cardiac catheterization laboratory to relieve ischemic chest pain. By increasing DBP and lowering LVEDP, the IABP improves the balance of LV myocardial oxygen supply and demand. In a 1997 review of 4,756 IAPB uses in a single institution over a period of 30 years, Torchiana et al. suggested that preoperative placement of an IABP in those with medically refractory ischemia can improve patient outcome.1 Guidelines continue to evolve in parallel with new evidence regarding the utility of the IABP in patients with ST-segment elevation myocardial infarction (STEMI) and cardiogenic shock to affect clinical outcomes (e.g., mortality). MacKay et al. recently reviewed the role of IABP use in cardiovascular practice and report that various guidelines have downgraded the strength of ...