Ann Thorac Surg 1996;61:988-990
© 1996 The Society of Thoracic Surgeons
Case Report
Right Ventricular Obstruction in Aortic Dissection: A Mechanism of Hemodynamic Collapse
Robert J. Downey, MD,
John H. M. Austin, MD,
Paolo Pepino, MD,
Marc L. Dickstein, MD,
Shunichi Homma, MD,
Eric A. Rose, MD
Division of Cardiothoracic Surgery, Departments of Radiology, Anesthesiology, and Medicine, Columbia-Presbyterian Medical Center, New York, New York
Accepted for publication September 15, 1995.
 |
Abstract
|
|---|
The main and right pulmonary arteries may be compressed by the false lumen of a type I aortic dissection. We report a 73-year-old women with a dissection of the aorta in whom echocardiographic examination revealed acute pulmonary arterial compression causing right ventricular failure and hemodynamic collapse.
|
Introduction
|
|---|
The right pulmonary artery and the ascending aorta share a common adventitia [1], which fixes the two structures one to another; thus, the false lumen of an ascending aortic dissection may compress the lower pressure pulmonary arterial system. We report echocardiographic evidence of acute right ventricular tract outflow obstruction by the dilated lumen of a type I aortic dissection, causing right ventricular failure.
A 73-year-old woman without significant prior medical history experienced sudden sharp left posterior chest pain and dyspnea, leading her to seek care at Columbia-Presbyterian Medical Center. Chest radiograph suggested a widened mediastinum. Computed tomograms revealed a DeBakey type I aortic dissection, severe compression of the distal main and right pulmonary arteries by the dilated ascending aorta (Fig 1A
), and a normal-caliber proximal main pulmonary artery (Fig 1B). Transesophageal echocardiography showed a tear in the aortic arch extending from the aortic annulus to the abdominal aorta, and mild aortic insufficiency. The echocardiogram also revealed compression of the right pulmonary artery by the false lumen of the aorta, dilatation and severe hypokinesis of the right ventricle, an empty but normally contractile left ventricle, and a small pericardial effusion (Figs 2, 3). Electrocardiograms showed no evidence of acute ischemic changes. The patient's respiratory rate rose to 32 breaths/min; arterial blood pH was 7.14, carbon dioxide tension was 32 mm Hg; and oxygen tension was 91 mm Hg on 100% inspired oxygen by face mask. Blood pressure fell to 80/50 mm Hg; simultaneously measured cardiac index was 1.46 L•min-1•m-2, pulmonary artery pressures were 35/12 mm Hg (mean 17), and central venous pressure was 11 mm Hg. Worsening hypotension precluded measurement of right ventricular pressures.
View larger version (193K):
[in this window]
[in a new window]
|
Fig 1. . Computed tomographic scans of the chest show major vessels outlined by radiopaque contrast medium, revealing an intimal flap (straight arrows) in both the ascending and descending thoracic aorta. In A, the main pulmonary artery is of normal caliber (large straight arrow) but in B, a mediastinal hematoma compresses the distal main pulmonary artery (large curved arrow) and the right pulmonary artery (open arrow).
|
|
View larger version (57K):
[in this window]
[in a new window]
|
Fig 2. . Transesophageal echocardiographic image of the proximal ascending aorta in horizontal plane demonstrates dilated aorta with true lumen (TL), false lumen (FL), and markedly compressed right pulmonary artery (RPA).
|
|
View larger version (79K):
[in this window]
[in a new window]
|
Fig 3. . Transgastric transesophageal echocardiographic image demonstrates small left ventricle (LV) and markedly dilated right ventricle (RV). A small pericardial effusion (PE) is also seen.
|
|
Repair of the dissection and decompression of the pulmonary artery was undertaken. The ascending aorta contained a posterior false lumen, which was filled with clotted blood, compressing the right pulmonary artery. There was a small bloody pericardial effusion; the coronary ostia and the arch vessels were patent. The ascending aorta was replaced with a 24-mm Dacron graft; the commissure between the right and noncoronary sinuses was resuspended. After discontinuation of cardiopulmonary bypass, repeat transesophageal echocardiography suggested restoration of flow through the right pulmonary artery and markedly improved right ventricular function. However, the patient never regained consciousness, renal failure developed, and the patient died on the tenth postoperative day.
|
Comment
|
|---|
Hypotension in a patient with an ascending aorta dissection has many recognized causes, including aortic valvular insufficiency, myocardial ischemia, and tamponade. Hemodynamic collapse can occur without clear evidence implicating any of these mechanisms. This report provides echocardiographic evidence of an additional mechanism of hemodynamic instability: pulmonary artery compression by the enlarged ascending aorta resulting in right ventricular failure.
The right pulmonary artery lies between the posterior wall of the ascending aorta and the vertebral column. The common adventitia shared by the aorta and the pulmonary artery limits the mobility of the pulmonary artery should the aorta enlarge, and blood that dissects into the aortic adventitia may encircle the pulmonary artery [2]. Systemic systolic pressure drives blood into the ascending aorta, compressing the low-pressure pulmonary artery. If the false lumen is thought of as one jaw of a pincer, the vertebral bodies and the descending aorta may act as the second jaw, compressing the posterior wall of the pulmonary artery. It is also possible that the descending aorta, if enlarged either by ectasia or a false lumen, may contribute to pulmonary arterial obstruction. Previously published case reports have provided computed tomographic and ventilation-perfusion scan evidence that compression of the pulmonary artery by the false lumen of the ascending aortic dissection has been seen to occur, but have focused on the differential diagnostic consideration of pulmonary embolism [3, 4]. Two reports have documented that the radiologic appearance of pulmonary artery compression may be associated with high pressure gradients between the right ventricle and the pulmonary artery. Roberts and associates [5] measured a 25-mm Hg peak systolic pressure gradient between the right ventricle and the pulmonary artery in a patient with near-complete occlusion of the right pulmonary artery by an ascending aortic dissection. In a patient with chronic compression of the main pulmonary trunk by a luetic ascending aortic aneurysm, Sahasakul and Chaithiraphan [6] recorded a systolic pressure gradient of 50 mm Hg between the right ventricle and the pulmonary artery.
Unfortunately, our patient's condition deteriorated during right heart catheterization; as systemic hypotension was present, the central pressures, pulmonary arterial pressures, and cardiac index measured are difficult to relate to a gradient across the right ventricular outflow tract. The computed tomograms obtained support the echocardiographic findings by demonstrating the proximal main pulmonary arterial trunk to be of normal diameter and compression of the distal common pulmonary arterial trunk and the right pulmonary artery by the false lumen of the ascending aorta (see Fig 1
). Therefore, when transesophageal echocardiographic examination of the aorta reveals an ascending aortic dissection in a hemodynamically compromised patient, right ventricular outflow tract obstruction should be considered as a possible cause.
|
Footnotes
|
|---|
Address reprint requests to Dr Downey, Division of Thoracic Surgery, Memorial Sloan-Kettering Cancer Center, 1275 York Ave, New York, NY 10021.
|
References
|
|---|
- Buja LM, Ali N, Fletcher RD, Roberts WC. Stenosis of the main pulmonary artery: a complication of acute dissecting aneurysm of the ascending aorta. Am Heart J 1972;83:89–92.[Medline]
- Roberts WC. Aortic dissection: anatomy, consequences, and causes. Am Heart J 1981;101:195–214.[Medline]
- Cramer M, Foley WD, Palmer TE, et al. Compression of the right pulmonary artery by aortic aneurysms: CT demonstration. J Comput Assist Tomogr 1985;9:310–4.[Medline]
- Zeit RM, Cope C, Lippman M. Compression of the pulmonary artery by aortic aneurysm. JAMA 1981;246:1586–8.[Abstract/Free Full Text]
- Roberts WC, Satler LF, Wallace RB. Hemodynamic confirmation of peripheral pulmonary stenosis caused by aortic dissection. Am J Cardiol 1989;63:1418–20.[Medline]
- Sahasakul Y, Chaithiraphan S. Aortic aneurysm masquerading as acquired pulmonary stenosis. J Med Assoc Thai 1984;67:118–23.[Medline]
This article has been cited by other articles:
|
|
|
|
 
Y. Inoue, R. Takahashi, I. Kashima, and K. Tsutsumi
Mediastinal hematoma: another lethal sign of aortic dissection
Interact CardioVasc Thorac Surg,
February 1, 2009;
8(2):
275 - 276.
[Abstract]
[Full Text]
[PDF]
|
|
|
Top
Abstract
Introduction
