What are the anesthetic considerations for a patient with Eisenmenger syndrome?

What are the anesthetic considerations for a patient with Eisenmenger syndrome?

Eisenmenger syndrome occurs in patients with congenital heart disease (CHD) who have had prolonged shunting of blood to the lungs with excessive pulmonary blood flow and pressure. It occurs after several years in patients who have uncorrected cardiac lesions, such as atrial septal defects, ventricular septal defects, or patent ductus arteriosus, with pulmonary-to-systemic blood flow ratios greater than 2:1 (left-to-right shunting). As irreversible changes occur in the pulmonary vasculature, the pulmonary vascular resistance (PVR) rises to the point where there is reversal of flow across the cardiac defect resulting in cyanosis (right-to-left shunting).

Once right-to-left shunting occurs, the cardiac defect is no longer surgically correctable. In Eisenmenger syndrome, the PVR is so high that an attempted surgical closure of the defect would cause the right ventricle to fail due to the increased impedance to ejection. The only possible surgi-cal treatment is heart-lung transplantation. Untreated Eisenmenger syndrome is associated with a poor long-term prognosis. These patients are at greatly increased risk for any elective procedure. They are usually anesthetized for emergency procedures as well as labor and delivery.

The anesthetic considerations are similar to those in any patient with CHD and right-to-left shunting. These con-cerns include managing a patient who could decompensate due to increased right-to-left shunting with worsened hypoxemia and/or myocardial dysfunction. Polycythemia is a major preoperative concern in these patients who are at risk of having thrombotic complications, especially if they are dehydrated. Preoperative phlebotomy or autologous blood donation should be considered if the hematocrit is >55–60%. These patients are also at high risk of paradoxi-cal embolization and bacterial endocarditis.

The ratio of pulmonary-to-systemic blood flow depends on the ratio of PVR to systemic vascular resistance (SVR). A decrease in SVR or an increase in PVR will increase right-to-left shunting and increase cyanosis. PVR is increased with low inspired oxygen concentration, acidosis, hypercarbia, hypothermia, high lung inflation pressures or positive end-expiratory pressures, endobronchial intubation, and high catecholamine levels.

The goal is to maintain the baseline PVR:SVR ratio. Preoperatively, the patient should be well hydrated. These patients may receive anesthetic premedication, but do not tolerate respiratory depression well. Supplemental oxygen may be helpful following sedative medications. Monitoring should be tailored to the procedure, but an intra-arterial line is indicated in all but the most minor procedures, such as monitored cases performed under local anesthesia. The indications for a pulmonary artery catheter are controversial. It may be impossible to enter the pulmonary artery, and the placement and maintenance of the pulmonary artery catheter may result in significant morbidity and mortality. A central line can often serve as an indicator of right ventricular function and allows for central administration of medications.

The anesthetic should be designed to minimize myocar-dial depression and PVR. To avoid enlarging any inadvertent air emboli, it is probably wisest to avoid nitrous oxide. Regional and general anesthetics have been used successfully but require judicious management, invasive monitoring, and appropriate hemodynamic interventions. For prophy-laxis against endocarditis, antibiotics must be administered early enough so that therapeutic tissue levels are achieved at the time of skin incision, and postoperative doses must be ordered (Tables 7.1, 7.2). Arrangements should be made to closely monitor the patient postoperatively.