Anesthesia in Adult Congenital Heart Disease, Including Anesthesia for Noncardiac Surgery

General Anesthesia for Cardiac Surgery

When general anesthesia is considered for a patient with ACHD, enough information must be collected from the best sources. A clear understanding of the functional anatomy is vital. Preoperative assessment of these patients is similar to that for any other surgical patient, with special attention directed toward anticoagulation and assessment of cardiorespiratory function, including the current level of exercise tolerance. Examination should be performed to establish the presence of congestive cardiac failure and cyanosis. In cases in which previous surgery has been undertaken, details of that surgical procedure are important because they will allow a better understanding of the patient’s anatomic and physiologic status. Investigations should be tailored to elucidate the cardiac anatomy and actively exclude or diagnose pulmonary hypertension, which is an independent risk factor for perioperative morbidity and mortality. Coronary angiography may be needed. The lateral chest radiograph, historically useful in assessing the relationship between the sternum and right ventricle, and particularly important in reoperation, has been superseded by magnetic resonance imaging, which is the radiologic imaging of choice. Special attention should be paid to renal, hepatic, and hematologic tests, particularly the presence of secondary erythrocytosis associated with chronic hypoxia.

In many cases, this will be “redo” surgery and provision must be made for rapid availability of blood and blood products if these are not immediately available on site. Adhesive external defibrillator pads should be used in patients who are undergoing second or subsequent cardiac surgery. The surgical challenges of reoperation in these patients should not be underestimated.

Sedative premedication may be prescribed (with supplemental oxygen), but care must be taken in cases of cyanotic heart disease or pulmonary hypertension in which hypercapnia can have profound deleterious effects on pulmonary vascular resistance.

Induction of anesthesia may need to be undertaken with invasive arterial pressure monitoring in situ. All standard induction agents have been used safely in these patients. Some practitioners prefer etomidate for induction because the extent of systemic vasodilation is lessened. Ketamine may confer some hemodynamic advantage but is limited by the frequency of dysphoric reactions. Of greater importance than the choice of agent is the speed and overall dose administered. Many of these patients have slow circulation times, and consequently there is a risk of overdose if the induction drug is injected too rapidly. Some practitioners titrate the induction agent until loss of the lash reflex and then supplement the induction with an opiate (eg, fentanyl). Neuromuscular blockade can be achieved with any nondepolarizing muscle relaxant, although many practitioners avoid atracurium because hypotension after histamine release may have a more marked hemodynamic effect in patients reliant on afterload to avoid shunting. Maintenance with an oxygen-air mixture and an inhalational agent is acceptable, as is total intravenous anesthesia. Nitrous oxide should be avoided because it causes myocardial depression. It is seldom necessary or advisable to ventilate with 100% oxygen.

Monitoring should include electrocardiography, saturation, core temperature, and ventilator parameters (eg, end-tidal carbon dioxide and inspired oxygen concentration). Central venous pressure measurements are essential, but the route of access should be discussed with reference to the surgical approach, and care should be taken with univentricular circulations in which thrombotic and embolic events are more common. Pulmonary artery catheters are rarely used because interpretation may be misleading in the presence of significant shunting, and the calculation of cardiac output by thermodilution is inaccurate in this setting. In all cases, meticulous attention must be paid during line insertion to prevent air emboli, which can be disastrous in patients with intracardiac defects. Transesophageal echocardiography is an essential additional monitor for the surgical procedure itself and adds additional information that may assist the anesthetist. Real-time interpretation allows rapid response to changing hemodynamic conditions.

Every effort should be made in the preoperative period to prevent postoperative hypothermia (shivering increases myocardial work) and hyperglycemia (which may worsen cerebral outcome).

All these patients should receive level 2 or 3 postoperative care (high dependency or intensive care). Detailed handover and discussion between cardiac surgeons, cardiac anesthetists, and intensivists help to ensure that appropriate care is maintained throughout the perioperative period. The length and complexity of the surgery often necessitate postoperative ventilation, but care must be taken to ensure that the deleterious effects of intermittent positive-pressure ventilation do not worsen cardiac function. Early extubation is preferred and may be associated with an improved outcome.

Fluid management should be carefully guided by hemodynamic response because many of these patients are particularly susceptible to congestive cardiac failure. Current trends in medical management with regard to fluid resuscitation and oxygen delivery may not apply to this population.

Guidelines from the National Institute for Health and Clinical Excellence recommend that routine antibiotic prophylaxis is not beneficial. This view is shared by the British Cardiovascular Society and European Society of Cardiology. However, prophylaxis should be considered in accordance with local guidelines, bearing in mind that postoperative sepsis and infective endocarditis carry higher mortalities than in the general population. Good oral hygiene and regular dental review are recommended for these patients.

Adequate analgesia must be provided. It not only forms part of standard postsurgical care but also reduces the likelihood of pulmonary hypertension in susceptible patients.