Peer Reviewed Content

ASSESSMENT OF MALPERFUSION SYNDROME IN AORTIC DISSECTION: DEFINING AN AORTIC DISSECTION LAB PANEL

Author: Edward Ranzenbach, DMSc, PA-C, CAQ-CVTS, FAPACVS, DFAAPA Assistant Professor - Director of Clinical Educational

Pfeiffer

University PA Program

Albemarle, NC

Abstract

Aortic dissection (AD) is a devastating disease process in which the intimal wall of the aorta tears, resulting in a false channel to which blood can enter. As blood enters this false channel, the dissection of the tunica intima away from the tunica media continues to grow, compressing and limiting the flow of blood through smaller arterial branches and possibly even shearing some of them off.

The rate of mortality from AD has been found to be as high as 45% and one of the biggest factors in predicting that mortality is the presence of malperfusion syndrome. In this article we examine the effects of malperfusion syndrome on survivability and the utilization of various laboratory investigations in determining the severity of malperfusion syndrome. The goal of this article is to establish a standard aortic dissection lab panel that should be drawn on every patient suspected of having an AD as soon as they present for diagnosis and treatment in an attempt to provide the cardiothoracic and vascular surgeon with the information necessary to plan the required type and timing of repair.

Introduction

The aorta arises from the heart and is the conduit for circulation throughout the body. The gateway to the aorta is the aortic valve. The aortic valve is located within the ventricular outflow tract, at the root of the base of the left ventricle. From proximal to distal, the aorta gives rise to major branches which provide circulation to the left and right main coronary artery, the innominate artery, at the beginning of the proximal arch, which then bifurcates into the right common carotid and the right axillary artery, the left common carotid artery, and the left subclavian artery. From there, the descending trunk of the artery provides branches supplying the vertebral column, the mesentery and abdominal organs, liver, and the renal arteries supplying both kidneys, before branching into the right and left iliac arteries to supply the lower limbs.

The aorta is composed of three layers, the outer layer being the tunica externa. The middle layer is a muscular layer, the tunica media, and provides the artery with the ability to expand and contract to assist in regulation of perfusion throughout the body. The innermost layer of the artery is the tunica intima (see Figure 1).

Aortic dissection occurs when the tunica intima is damaged. This tear in the thin intimal wall of the aorta allows blood to forcefully separate the tunica intima from the tunica media, creating a false lumen or channel. As the false lumen continues to grow, it can compress the true lumen and obstruct flow to branches supplying blood to the organs downstream. Aortic dissection can even shear off smaller arterial takeoffs as well. The end result is decreased perfusion to the tissues supplied by the involved arterial branches.