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Questions

  

D.1. Detail the anesthetic management for a patient undergoing LVAD placement

Answer:

Management of patients requiring LVAD placement can be divided into the preoperative, intraoperative, and postoperative periods.

Preoperatively, a patient requiring an LVAD will, by definition, have severely reduced LV function. They may require mechanical ventilation, multiple inotropes, vasopressors, and/or an IABP. Due to chronic heart failure and its treatment, such patients can have profoundly abnormal electrolytes, liver, renal, and coagulation function tests. Preoperative echocardiography demonstrating the presence of pulmonary hypertension, impaired RV function, or tricuspid regurgitation is particularly important because these findings indicate the possible need for RV support or even placement of a right ventricular assist device. Severe irreversible pulmonary hypertension, severe tricuspid regurgitation, and severe RV dysfunction can be a contraindication for an LVAD or indicate the need for a biventricular ventricular assist device (BiVAD).

An arterial catheter is placed prior to the induction of anesthesia for monitoring. No matter the choice of anesthetic, myocardial depression or rapid changes in systemic vascular resistance must be avoided. Given patients' slow circulation, preemptive administration of vasopressors is prudent to offset unwanted side effects of induction agents. To avoid possible acute RV dysfunction due to hypoxia and hypercarbia, ventilation and tracheal intubation should be accomplished expeditiously. Early administration of neuromuscular blocking agents and controlled lung ventilation with low inspiratory airway pressure are suggested to avoid increases in intrathoracic pressure that can have a deleterious effect on the right heart. Once anesthesia is successfully induced, ICDs must be deactivated, and the pacing mode changed to allow use of intraoperative electrocautery. Large-bore peripheral and central intravenous access and a PAC should be placed. Large-bore venous access is especially important for patients who have had prior cardiac surgery because of the risk of adhesions and massive hemorrhage. Blood and blood products should be available in case of major bleeding.

Intraoperatively, the anesthetic goals are to avoid deterioration of existing cardiac function, to avoid hypovolemia and anemia, and to optimize cardiovascular status while the LVAD is implanted under CPB. Because the primary concern in a patient undergoing an LVAD implantation is RV failure, real-time monitoring of central venous pressure (and its association with pulmonary pressures) is crucial. TEE is invaluable in patients undergoing LVAD placement, and a complete echocardiographic assessment should be performed on every patient. The focus of TEE examination is assessment of (1) atrial septal defects, which can predispose to hypoxemia due to right-to-left shunting after VAD placement as left atrial pressures are decreased; (2) aortic regurgitation, which will cause a "recycling" of blood from the aorta back to the LV; (3) tricuspid regurgitation, which can cause or exacerbate RV failure; (4) mitral stenosis, which can decrease LV filling and therefore the "preload" to the LVAD; (5) an intracardiac LV thrombus; and (6) preexisting RV dysfunction.

Following LVAD implantation and following CPB, focus is placed on maintaining euvolemia, treating coagulation abnormalities, and supporting RV function. Vasoactive medications and inotropes are infused and frequently inhaled such as nitric oxide (NO) or prostacyclin, which are administered to ameliorate pulmonary hypertension. Those patients treated with pulmonary vasodilators early after LVAD placement had a decreased incidence of RV failure in observational studies. Patients with VADs require long-term anticoagulation.

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