3D Echocardiographic Assessment of Epicardial Pacing After Cardiopulmonary Bypass.

Suzanne Flier, MD40 enrolled

Overview

This study evaluates the usefulness of 3D echocardiography to guide pacemaker therapy in the operating room in cardiac surgical patients. Each patient will serve as his own control, following a paired design.

Cardiac surgical patients sometimes require temporary pacing wires to optimize cardiac function during weaning from cardiopulmonary bypass (CPB), and/or to treat hemodynamically significant brady-arrhythmias. The available patient series report that 8.6% to 23.9% of patient undergoing coronary artery bypass grafting (CABG) or valve surgery require temporary pacing at some time after CPB. The site of pacemaker wire placement seems to be a crucial determinant of cardiac output. In non-surgical patients isolated right ventricular (RV) pacing seems to induce electromechanical dyssynchrony of the RV and the left ventricle (LV). A normal ventricle in sinus rhythm displays a simultaneous contraction of all segments of the heart, so that regional minimal volume (i.e. maximal contraction) will occur at the same time. Isolated RV pacing seems to result in a left bundle branch type electrical activation sequence, with delayed contraction of some of the segments. The LV, but not the RV, seems to negatively affected by this state of dyssynchrony, resulting in decreased cardiac output. In surgical patients however, there is not such data available yet. Since isolated RV epicardial wire placement is still widely practiced in cardiac surgery, and in our own institution, we would like to study the effect of RV pacing on LV synchrony and LV output. Again from studies in non-surgical patients receiving resynchronization therapy, we know that real-time three-dimensional (3D) echocardiography is very useful to pick up subtle changes in LV synchrony and thereby guide synchronization of ventricular contraction. However, to date the usefulness of real-time 3D echocardiography to guide pacemaker therapy in cardiac surgery is unknown. In the present feasibility study in cardiac surgical patients, we want to investigate the acute effects of isolated RV pacing on LV synchrony, and LV output.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

DIAGNOSTIC

Masking

DOUBLE

Enrollment

Conditions

Disorder of Pacing Function

Interventions

Right ventricular epicardial pacingDEVICE

The patient's own heart rate at that moment will be the starting point for the study. Right ventricle pacing will be instituted by selecting a rate that is 5 beats above the patient's own heart rate. We will use a stepwise approach where we increase the pacermaker's rate with steps of 5 beats until we have 100% capture of the pacemaker beats. After waiting for at least one minute of pacing we will obtain a set of measurements.

cardiac surgeryPROCEDURE

Elective cardiac surgery, with use of cardiopulmonary bypass.

3D TEEDEVICE

Intraoperatively, all patients will be monitored by means of TEE

Eligibility

Sex: ALLMin age: 18 Years

Medical Language ↔ Plain English

Inclusion Criteria: * Adult patient scheduled to undergo elective cardiac surgery by means of full sternotomy and use of cardiopulmonary bypass * Preoperative moderate to good LV function, ejection fraction \> 30% * Age \> 18 yrs. old * Preoperative sinus rhythm * Pacemaker lead inserted by cardiac surgeon during surgery * Underlying sinus rhythm after cardiopulmonary bypass before the end of surgery * Able to understand written and verbal patient information * Signed informed consent Exclusion Criteria: * Emergency cardiac surgery * Minimally invasive surgery * Contraindication to TEE * Redo surgery * Hemodynamic instability after CPB (late exclusion criterium) * No pacemaker lead inserted by cardiac surgeon (late exclusion criterium) * No sinus rhythm during chest closure towards the end of surgery (late exclusion criterium)

Locations (1)

University Hospital - London Health Sciences Centre

London, Ontario, Canada

Outcomes

Primary Outcomes

Left ventricular systolic dyssynchrony index (SDI)

For each segment of 16 segments excluding the apical cap in a standard 17-segment model, the time to reach regional minimal volume is calculated as a fraction of the total cardiac cycle (RR interval) and expressed as a percentage.10 The standard deviation of these measurements is defined as the SDI. Three-dimensional SDI is therefore the dispersion time to reach the minimum systolic volume (as recommended).

Time frame: Intraoperative, end of cardiac surgery (duration 10 minutes)

Secondary Outcomes

Ventricular volumes and ejection fraction

We will obtain a full volume 3D dataset and obtain end diastolic (EDV) and end systolic volume (ESV). By subtracting ESV from EDV we will obtain the ejection fraction (EF).

Time frame: Intraoperative, end of cardiac surgery (duration 10 minutes)

LVOT blood flow

As a surrogate for cardiac output we will obtain the velocity time integral (VTI) across the left ventricular outflow tract (LVOT)

Time frame: Intraoperative, end of cardiac surgery (duration 10 minutes)

Presence and severity of mitral regurgitation

From midesophageal position we will perform a transesophageal echocardiography (TEE) study to interrogate the mitral valve for the presence and severity of mitral regurgitation.

Time frame: Intraoperative, end of cardiac surgery (duration 10 minutes)

Data from ClinicalTrials.gov

This platform is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional.