Systolic anterior motion of the mitral valve—the mechanism of postural hypotension following left intrapericardial pneumonectomy

Abstract

Systolic anterior motion (SAM) is defined as displacement of the distal portion of the anterior leaflet of the mitral valve toward the left ventricular outflow tract obstruction. SAM can occur in patients without hypertrophic cardiomyopathy (HOCM) and is a well-recognized cause for unexplained sudden hypotension in perioperative settings. We present a case of persistent orthostatic hypotension caused by SAM following left intrapericardial pneumonectomy and mediastinal lymph node dissection for squamous cell carcinoma of the lung invading intrapericardial portion of the inferior pulmonary vein. Diagnosis of SAM was possible with the use of transesophageal echocardiography (TEE). J Thorac Dis 2017;9(4):E354-E357 jtd.amegroups.com utilizing 60 mm TA stapler with blue (3.5 mm) staple load. Essentially all pericardium to the left of the midline was also resected en bloc with the specimen. Since the heart was laying anatomically oriented in the left chest without any tension on the venous return, and because of the very large size of pericardial defect, the pericardium was not reconstructed. Chest cavity was closed with one drain in place connected to post pneumonectomy pleurovac.Patient remained hemodynamically stable for the first 24 hours, however, on postoperative day (POD) 2 started experiencing severe postural hypotension {81/53 [62] mmHg}, which temporarily responded to fluid boluses, and subsequently required phenylephrine infusion at 50 mcg per minute. Patient also manifested hepatojugular reflux with jugular venous distention. Right heart failure and pulmonary hypertension were considered in the differential diagnosis, and bedside transesophageal echocardiography (TEE) showed the right ventricle mildly dilated with mildly depressed right ventricular systolic function, dilation of the right atrium, and left atrium small in size. Computed tomography (CT) scan of the chest, however, demonstrated evidence of left atrial compression, suggesting dynamic obstruction of the venous return from the remaining right-sided pulmonary veins (Figure 2). Due to the patient's hemodynamic instability off of phenylephrine, the decision was made to take the patient back to the operating room for a redo thoracotomy and a pericardial reconstruction with bovine pericardium (12×25 cm bovine pericardium) on POD 4.On arrival to the operating room, patient was in the supine position and demonstrated stable hemodynamics with four liters of supplemental oxygen and phenylephrine infusion at 0.3 mcg/kg/min. A pre-induction arterial line was placed and vital signs were as follows; blood pressure 139/72 [99] mmHg, heart rate of 84 bpm, respiratory rate of 14, and oxygen saturation of 95%. After a smooth induction the patient was easily intubated with a single lumen endotracheal tube. A 9-French central line was placed in the right internal jugular vein with ultrasound guidance. Upon insertion of the central line, the patient's baseline CVP was 23 mmHg in supine position. An orogastric tube was inserted to empty and decompress the...

Mitral Valve Systolic Anterior Motion in Robotic Thoracic Surgery as the Cause of Unexplained Hemodynamic Shock: From a Case Report to Recommendations

“…The management of patients with SAM in RATS includes peculiar treatment strategies, which, if not promptly and properly applied, may lead to catastrophic consequences. Notably, cases of SAM-related LVOTO are already reported in noncardiac surgery [ 36 , 37 ] and thoracic surgery [ 38 ] but never in RATS. In particular, the only case report in thoracic surgery was reported by Lasala et al, which observed the development of SAM in a patient with postural hypotension 2 days after surgery in the left thoracotomy.…”