- 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 ventricular function preoperatively can deteriorate intraoperatively secondary to inadequate myocardial preservation, embolism, myocardial ischemia, protamine reactions, and other "catastrophic" events (eg, anaphylaxis, aortic dissection, etc). Of course, the overwhelming majority of patients experiencing intra-operative right or left ventricular failure can be treated with a combination of inotropes and nitric oxide inhalation. However, others lack sufficient ventricular function to provide adequate delivery of oxygenated blood to the tissues. Such patients readily develop renal dysfunction, acidosis, and ultimately die from 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).
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. The patient must have some cardiac output even if not adequate. IABP is generally introduced via the femoral artery into the thoracic aorta and positioned distal to the take off of the left subclavian artery. The IABP inflates with carbon dioxide or helium during diastole and deflates during systole. Thus, it creates a counterpulsation to the pulsation generated by the heart. By inflating during diastole at the point of aortic valve closure, they augment diastolic blood pressure and thus improve coronary perfusion pressure (CPP) of the left ventricle (LV).
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 can improve the balance of LV myocardial oxygen supply and demand. In a 1997 review of 4756 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
In patients with cardiogenic shock, the IABP is placed to augment cardiac output in the immediate preoperative period should emergent heart surgery be warranted. Of note, the IABP is contraindicated in patients with aortic dissections, aortic aneurysms, severe aortic insufficiency, and severe atherosclerotic disease in the descending aorta.
IABPs are placed in the operating room in those patients ...