Patients with chronic thromboembolic pulmonary hypertension (CTEPH) present challenges from a surgical and anesthetic standpoint. They often have significant pulmonary collateral vessels to bypass obstructed pulmonary vessels. This, in turn, can increase bronchial vessel flow which can congest the pulmonary vessels even during bicaval venous cannulation. Additionally, large thromboembolic loads create large areas of dead space leading to V/Q mismatch with potential issues like hypoxemia and hypercarbia. This, in turn, can stress the right side of the heart leading to right ventricular pressure/volume overload, functional tricuspid regurgitation, elevated venous pressures, etc.
Pulmonary thromboendarterectomy (PTE) is the “gold standard” treatment for these patients. My anesthetic plan for PTE includes: general endotracheal anesthesia, arterial line (sometimes bilateral radial lines if anterograde cerebral perfusion is planned), central venous catheter with a PA catheter, inhaled pulmonary vasodilators (Veletri/Flolan) and intraoperative transesophageal echocardiography (TEE). In particular with TEE, I’m looking for signs of right ventricular failure, clots, an underfilled left ventricle, etc.
After a median sternotomy and systemic heparinization, the ascending aorta (arterial) and the SVC/IVC (bicaval venous) are cannulated in preparation for cardiopulmonary bypass (CPB). An aortic root vent is placed and CPB is initiated. At this point, a left atrial vent is placed via the right superior pulmonary vein (RSPV) and cooling for deep hypothermic circulatory arrest (DHCA) is initiated. The right pulmonary artery (RPA) is opened with an endarterectomy carried to the segmental branches. A mirror procedure is performed on the left pulmonary artery (LPA).
Once we reach ~ 18-20°C, circulatory arrest begins and the remainder of the RPA endarterectomy is completed. Perfusion is resumed while closing the RPA. A mirror procedure is again carried on the LPA. DHCA allows the surgeon to have a bloodless field to optimize their endarterectomy. After rewarming, protamine administration, and CPB decannulation, hemostasis is achieved and the chest is closed in anatomic layers.
In the ICU, it’s important to watch for signs of reperfusion injury and remain judicious about volume administration.
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