Pulmonary Thromboendarterectomy for Chronic Thromboembolic Pulmonary Hypertension

Introduction
Chronic thromboembolic pulmonary hypertension (CTEPH) occurs in less than 3.8% of pulmonary embolism (PE) cases. It results from concomitant pulmonary vascular obstruction and small-vessel fibrointimal hyperplasia, which leads to elevated pulmonary artery pressures, elevated pulmonary vascular resistance, and subsequent right heart failure [1-4]. If left untreated, CTEPH is fatal. Medical therapy remains unsatisfactory. Pulmonary thromboendarterectomy is curative by reducing pulmonary vascular resistance and improving right ventricular dysfunction [1-4].

Patient Presentation
A 37-year-old woman presented with altered mental status and profound hypoxia. She had a history of PEs and end-stage renal disease on hemodialysis. Computed tomography angiogram demonstrated organized lining thrombi, causing vascular obstruction in branches of both pulmonary arteries. Significant thrombus was also demonstrated in the right atrium and superior vena cava. Transesophageal echocardiography revealed a significantly dilated right ventricle and severe tricuspid regurgitation. An Impella RP® (Abiomed, Danvers, MA, USA) device was placed for severe right ventricular failure. Thrombolysis was attempted but it failed. Weaning from Impella support was also unsuccessful, and a decision to perform a pulmonary thromboendarterectomy was made.

Surgical Technique
Median sternotomy was performed. The pericardium was incised and retracted. The patient was fully heparinized. Ascending aorta and bicaval venous cannulation were performed. A pulmonary artery vent was placed in the midline of the pulmonary trunk. Total cardiopulmonary bypass was initiated. An additional vent was placed in the left atrium via the right superior pulmonary vein. During cooling, the right pulmonary artery and superior vena cava were mobilized.

Right Atriotomy
A right atriotomy extending to the superior vena cava was performed. The superior vena cava was opened. A significant old thrombus was removed. No persistent foramen ovale was identified. The right atriotomy was closed with a pericardial patch using a 4-0 polypropylene suture.

Right Pulmonary Endarterectomy
The right pulmonary artery was approached, medial to the superior vena cava. After the patient was cooled to 20°C, the aorta was cross-clamped and a single dose of Custodiol-HTK cardioplegic solution was administered. An incision was made in the right pulmonary artery and carried past the take-off of the middle lobe artery. Circulatory arrest was then initiated. An olive tip suction instrument was used to develop a thromboendarterectomy plane. The thromboendarterectomy extended into the subsegmental vessels. Once the right-sided thromboendarterectomy was completed, circulation was restarted and the arteriotomy was repaired using a pericardial patch with a continuous 6-0 polypropylene suture. The total circulatory arrest time was 15 minutes.

Left Pulmonary Endarterectomy
Circulatory arrest was reinitiated after 20 minutes of reperfusion. The left pulmonary artery was incised beginning at the midpoint of the pulmonary trunk. The Impella device was retracted away from the left pulmonary artery. A thromboendarterectomy of the segmental and subsegmental branches was done. After the left-sided thromboendarterectomy was completed, the Impella device was reinserted and the arteriotomy was closed. Circulation was restarted. The total circulatory arrest time was 15 minutes.

Outcome and Discussion
A significant decrease in systolic pulmonary artery pressures from 80 mm Hg to 40 mm Hg was noted postoperatively. The Impella device was removed on postoperative day 10. The patient required a percutaneous tracheostomy due to ventilator-dependent respiratory failure. The patient was discharged to a rehabilitation facility where she successfully underwent decannulation. Contemporary results of pulmonary thromboendarterectomy are excellent, with low in-hospital mortality (2.2%), significantly reduced mean systolic pulmonary artery pressures (75.5 mm Hg to 41.7 mm Hg), and excellent long-term survivorship (75% at 10 years) [1].

References

1. Madani MM, Auger WR, Pretorius V, et al. Pulmonary endarterectomy: recent changes in a single institution's experience of more than 2,700 patients. Ann Thorac Surg. 2012;94(1):97-103.
2. Thistlethwaite PA, Kaneko K, Madani MM, Jamieson SW. Technique and outcomes of pulmonary endarterectomy surgery. Ann Thorac Cardiovasc Surg. 2008;14(5):274-282.
3. Madani MM, Jamieson SW. Technical advances of pulmonary endarterectomy for chronic thromboembolic pulmonary hypertension. Semin Thorac Cardiovasc Surg. 2006;18(3):243-249.
4. Guerin L, Couturaud F, Parent F, et al. Prevalence of chronic thromboembolic pulmonary hypertension after acute pulmonary embolism. Thromb Haemost. 2014;112(3):598-605.