Disorder of Pacing Function
Conditions
Keywords
Echocardiography, Three-dimensional, Cardiac Surgical Procedures, Cardiac Pacing, Artificial, Anesthesia
Brief summary
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
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.
Interventions
DEVICERight ventricular epicardial pacing
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.
PROCEDUREcardiac surgery
Elective cardiac surgery, with use of cardiopulmonary bypass.
DEVICE3D TEE
Intraoperatively, all patients will be monitored by means of TEE
DEVICEPacemaker lead
All patients will have a epicardial pacemaker lead in situ.
Sponsors
Suzanne Flier, MD
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
DIAGNOSTIC
Masking
DOUBLE (Subject, Outcomes Assessor)
Intervention model description
Sequence of measurements, during sinus rhythm and during pacing is randomized.
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No
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)
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Left ventricular systolic dyssynchrony index (SDI) | Intraoperative, end of cardiac surgery (duration 10 minutes) | 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). |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Ventricular volumes and ejection fraction | Intraoperative, end of cardiac surgery (duration 10 minutes) | 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). |
| LVOT blood flow | Intraoperative, end of cardiac surgery (duration 10 minutes) | As a surrogate for cardiac output we will obtain the velocity time integral (VTI) across the left ventricular outflow tract (LVOT) |
| Presence and severity of mitral regurgitation | Intraoperative, end of cardiac surgery (duration 10 minutes) | From midesophageal position we will perform a transesophageal echocardiography (TEE) study to interrogate the mitral valve for the presence and severity of mitral regurgitation. |
Countries
Canada
Outcome results
None listed