Approval Sheet Impact of Aortic Manipulation During Coronary Artery Bypass Surgery: The Effect of Aortic Clamping Strategies on Postoperative Stroke Open Access

Abstract

Objectives: The purpose of this study was to determine the impact of different aortic
clamping strategies during coronary artery bypass graft surgery (CABG) on incidence of
postoperative stroke.
Methods: In this case-control study, all patients at Emory hospitals from 2002-2009
(N=140) with postoperative stroke after isolated CABG were matched 4:1 to a
contemporaneous cohort of patients without postoperative stroke (N=565). Patients were
matched according to the Society of Thoracic Surgeons (STS) Predicted Risk of
Postoperative Stroke (PROPS) based on 26 variables. On- and off-pump CABG patients
were matched separately. Operative notes were reviewed to document operative
technique. Multiple logistic regression analysis with adjusted odds ratios (OR) was
performed to identify operative variables associated with postoperative stroke.
Results: Within the on-pump CABG cohort, the single cross-clamp technique was
associated with a decreased risk of postoperative stroke compared to the cross clamp and
partial clamp (double clamp) technique (OR=0.385, p=0.044). Within the off-pump
cohort, no significant difference was found between partial clamping and no clamping.
In 2002, 47/86 patients (54.6%) did not have epiaortic exam performed, compared to only
7/66 (10.6%) in 2009. Epiaortic ultrasound grading was performed in 525 patients
(74.4%): 75(14.3%) had grade 3-5 and 450(85.7%) had grade 1-2 aortic disease. In
patients with epiaortic grades 3-5, a clampless technique was used in 59.5%, 83.3%, and
93.3% of cases, respectively. In patients with epiaortic grades 1-2, clampless techniques
were used in 3.8% and 7.8%, respectively. No grade 5 patients had a postoperative
stroke. Clamp use in general trended downwards from 97.7% of cases in 2002 to 72.7%
of cases in 2009.
Conclusions: Aortic clamping during CABG may increase the risk of postoperative
stroke. Epiaortic ultrasound use has trended upwards from 2002 to 2009, indicating a
greater awareness of potential complications from aortic clamping and allowing for
changes in operative technique. A single cross-clamp strategy was associated with a
lower risk of postoperative stroke compared to the double clamp strategy in on-pump
patients. Using a no clamp technique may reduce the risk of postoperative stroke in off-
pump patients with grade 3-5 aortic disease by eliminating the need for aortic clamping
during CABG.

Table of Contents

Table of Contents
Title
page 1
Abstract
pages 2-3
Introduction
pages 4-5
Background
pages 6-8
Methods
pages 9-13
Results
pages 14-15
Discussion
pages 16-23
References
pages 24-28
Tables
pages 29-36
Figures
pages 37-41

About this Master's Thesis

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School	Laney Graduate School
Department	Clinical Research Curriculum Program
Degree	MS
Submission	Master's Thesis
Language	English
Research Field	Health Sciences, Medicine and Surgery
Keyword	postoperative stroke cardiopulmonary bypass aortic clamping coronary artery bypass surgery
Committee Chair / Thesis Advisor	Puskas, John D, Emory University
Committee Members	Boring, John R, Emory University Klein, Mitchel, Emory University

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