3D Echocardiographic Assessment of Epicardial Pacing After Cardiopulmonary Bypass.

Study Overview
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Brief Summary
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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.

Detailed Description
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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.

Official Title
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The Hemodynamic Effect of Transient Epicardial Right Ventricular Pacing After Cardiopulmonary Bypass, Assessed by Real-time Three-dimensional Echocardiography.

Conditions
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Disorder of Pacing Function

Intervention / Treatment
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* Device: Right ventricular epicardial pacing
* Procedure: cardiac surgery
* Device: 3D TEE
* Device: Pacemaker lead


Participation Criteria
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Eligibility Criteria
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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)

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Diagnostic
Allocation: Randomized
Intervention Model: Crossover Assignment
Interventional Model Description: Sequence of measurements, during sinus rhythm and during pacing is randomized.
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Sham Comparator: Non-paced<br>cardiac surgery 3D TEE measurements of systolic dyssynchrony right ventricular epicardial pacemaker lead (off) | Procedure: cardiac surgery<br>* Elective cardiac surgery, with use of cardiopulmonary bypass.<br>Device: 3D TEE<br>* Intraoperatively, all patients will be monitored by means of TEE<br>* Other names: three-dimensional transesophageal echocardiography;Device: Pacemaker lead<br>* All patients will have a epicardial pacemaker lead in situ.<br>|
| Experimental: Paced<br>The patient is randomized to the order of measurements taken, and serves as his own control. cardiac surgery 3D TEE measurements of systolic dyssynchrony right ventricular epicardial pacemaker lead (on) | Device: Right ventricular epicardial pacing<br>* 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.<br>Procedure: cardiac surgery<br>* Elective cardiac surgery, with use of cardiopulmonary bypass.<br>Device: 3D TEE<br>* Intraoperatively, all patients will be monitored by means of TEE<br>* Other names: three-dimensional transesophageal echocardiography;Device: Pacemaker lead<br>* All patients will have a epicardial pacemaker lead in situ.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| 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). | Intraoperative, end of cardiac surgery (duration 10 minutes) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| 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). | 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) | 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. | Intraoperative, end of cardiac surgery (duration 10 minutes) | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Echocardiography, Three-dimensional, Cardiac Surgical Procedures, Cardiac Pacing, Artificial, Anesthesia