Original Article
Transesophageal Echocardiography Guidance of Antegrade Cardioplegia Delivery for Cardiac Surgery

https://doi.org/10.1053/j.jvca.2015.03.009Get rights and content

Objectives

The initial volume of antegrade cardioplegia used to induce asystole during aortic cross-clamp still is based on empiric methods and may be excessive, potentially leading to hyperkalemia, myocardial edema, and acute left ventricular distention from aortic regurgitation. The objectives were to determine whether the volume of cardioplegia required to induce asystole is proportional to left ventricular mass, and whether the degree of left ventricular distention is proportional to the severity of aortic regurgitation.

Design

Prospective observational study.

Setting

Two tertiary university hospitals.

Interventions

Transesophageal echocardiography was used to estimate left ventricular mass (prolate ellipse revolution formula), quantify aortic regurgitation, and monitor for distention during initial antegrade cardioplegia delivery. The volume of cardioplegia required for asystole was recorded.

Participants

Fifty-eight patients aged over 18 years scheduled for cardiac surgery requiring aortic cross-clamping.

Measurements and Main Results

There was a weak correlation of left ventricular mass and antegrade cardioplegia volume required for asystole (r = 0.35, p = 0.047). The degree of left ventricular distention correlated moderately with the severity of aortic regurgitation (r = 0.55, p = 0.007) and was excessive and stopped early (aborted) in 24% of all patients, including 18% of 39 patients without aortic regurgitation. An aortic regurgitation vena contracta of 0.3 cm predicted aborted cardioplegia with modest accuracy (AUC 0.81, 0.66-0.99, p = 0.02, sensitivity 71%, specifity 81%).

Conclusions

Estimated left ventricular mass is not a useful predictor of the initial volume of antegrade cardioplegia required to induce asystole. However transesophageal echocardiography can predict and monitor for left ventricular distention, which is common.

Section snippets

Methods

This prospective cohort study received ethics approval from the Monash Health (12399Q) and Melbourne Health (QA2013047) Human Research Ethics Committees as a quality assurance project, and patient consent was not required. Patients were screened when the primary investigator was available (convenience sampling) from consecutive patients older than 18 years presenting for cardiac surgery requiring cardiopulmonary bypass (CPB) and myocardial protection during aortic cross-clamping with antegrade

Statistical Analysis

The estimated sample size of 60 patients was based on unpublished data from a pilot study. In the pilot study, a moderate correlation (r = 0.67) between estimated LV mass and volume of cardioplegia required for asystole was found by a single observer in 14 consecutive patients undergoing CABG surgery without detectable AR. Using an estimated incidence of at least trivial AR in cardiac surgical patients of 33%, this would require 21 patients to enroll 14 patients without AR. However, in the

Results

Out of 60 patients recruited between December 2012 and February 2014, 2 patients were excluded, leaving 58 patients with data for analysis. One patient was excluded due to inadequate echocardiography imaging (no transgastric views), and another patient was excluded as the surgery was performed without cardioplegia. Patient characteristics and surgical data are shown in Table 1.

Aortic regurgitation (of any severity) was detected in 19 patients who were excluded from the correlation analysis of

Discussion

The authors’ study showed that the estimation of LV mass by intraoperative TEE was not clinically useful for estimating the amount of initial volume of antegrade cardioplegia required to achieve asystole. However, it was shown that TEE was useful for routine monitoring for left ventricular distention during antegrade cardioplegia delivery as excessive LV distention was common, requiring conversion to retrograde delivery to achieve asystole in a quarter of patients and occurs in nearly 20% of

Acknowledgments

The authors are grateful for the assistance from the cardiac surgeons, anesthetists, and clinical perfusionists at Monash Medical Centre and The Royal Melbourne Hospital who assisted with data collection. They also thank Sandy Clarke and Darsim Haji for statistical advice. There was no funding provided or competing interests declared.

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