Pacing in Patients With Congenital Heart Disease
Pacing in Patients With Congenital Heart Disease
Ebstein's anomaly is characterised by failure of delamination of the tricuspid valve leaflets with resultant apical displacement of the septal leaflet (± posterior leaflet) (Figure 3). The displaced tricuspid valve divides the RV into two parts – an atrialised portion lying between the tricuspid annulus and the displaced tricuspid orifice, and the remainder of the true RV, which lies beyond the tricuspid valve.
(Enlarge Image)
Figure 3.
The diagnosis of Ebstein's anomaly is usually made by echocardiography. The left two-dimensional image shows the apically displaced tricuspid leaflet (S), grossly dilated right atrium (RA), atrialised portion of the right ventricle (*). The left ventricle (LV) is compressed due to the grossly enlarged right heart. The right colour-Doppler frame confirms the presence of severe tricuspid regurgitation secondary to failure of the tricuspid valve leaflets to co-apt
The relevance to pacemaker implanters is that approximately 20–25% of such patients develop arrhythmias and conduction abnormalities and 3–4% require pacing. The most common indications for pacing include persistent atrial standstill and AV block (de novo, post-AV node ablation or post-surgery). The atrialised portion of the RV varies in size, muscularity and thickness, but it has the electrophysiological characteristics of the RV. Hence, the RV lead can be placed above the valve rather than through it. Active fixation leads should be used in the atrium, the atrialised portion of the RV and in the RV apex or RV outflow tract to avoid displacement in such patients, who often have significant tricuspid regurgitation. It is worth remembering that other congenital cardiac defects may co-exist with Ebstein's anomaly, e.g. atrial septal defect, ventricular septal defect. When it is impossible to insert electrodes in the right atrium and ventricle, one may use the cardiac veins via the coronary sinus to achieve left ventricular pacing. However, in pacemaker-dependent patients, epicardial pacing may be more appropriate.
During the surgical correction for the tricuspid valve (reconstruction/replacement), a pacing lead can be inserted intra-operatively. After annuloplasty, the lead can be placed across the valve in the usual fashion. If valve replacement is required, a lead can be buried behind the sewing ring and the lead tunnelled to the anterior abdominal wall or pectoral region and connected to a generator, or capped for future use. Generally, however, if a mechanical prosthesis is implanted, epicardial pacing should be the method of choice, although, even here, endocardial pacing is not impossible if the coronary sinus is positioned on the atrial side of the prosthesis. Permanent pacing leads can be placed across a bio-prosthetic tricuspid valve without too much difficulty.
Ebstein's Anomaly
Ebstein's anomaly is characterised by failure of delamination of the tricuspid valve leaflets with resultant apical displacement of the septal leaflet (± posterior leaflet) (Figure 3). The displaced tricuspid valve divides the RV into two parts – an atrialised portion lying between the tricuspid annulus and the displaced tricuspid orifice, and the remainder of the true RV, which lies beyond the tricuspid valve.
(Enlarge Image)
Figure 3.
The diagnosis of Ebstein's anomaly is usually made by echocardiography. The left two-dimensional image shows the apically displaced tricuspid leaflet (S), grossly dilated right atrium (RA), atrialised portion of the right ventricle (*). The left ventricle (LV) is compressed due to the grossly enlarged right heart. The right colour-Doppler frame confirms the presence of severe tricuspid regurgitation secondary to failure of the tricuspid valve leaflets to co-apt
The relevance to pacemaker implanters is that approximately 20–25% of such patients develop arrhythmias and conduction abnormalities and 3–4% require pacing. The most common indications for pacing include persistent atrial standstill and AV block (de novo, post-AV node ablation or post-surgery). The atrialised portion of the RV varies in size, muscularity and thickness, but it has the electrophysiological characteristics of the RV. Hence, the RV lead can be placed above the valve rather than through it. Active fixation leads should be used in the atrium, the atrialised portion of the RV and in the RV apex or RV outflow tract to avoid displacement in such patients, who often have significant tricuspid regurgitation. It is worth remembering that other congenital cardiac defects may co-exist with Ebstein's anomaly, e.g. atrial septal defect, ventricular septal defect. When it is impossible to insert electrodes in the right atrium and ventricle, one may use the cardiac veins via the coronary sinus to achieve left ventricular pacing. However, in pacemaker-dependent patients, epicardial pacing may be more appropriate.
During the surgical correction for the tricuspid valve (reconstruction/replacement), a pacing lead can be inserted intra-operatively. After annuloplasty, the lead can be placed across the valve in the usual fashion. If valve replacement is required, a lead can be buried behind the sewing ring and the lead tunnelled to the anterior abdominal wall or pectoral region and connected to a generator, or capped for future use. Generally, however, if a mechanical prosthesis is implanted, epicardial pacing should be the method of choice, although, even here, endocardial pacing is not impossible if the coronary sinus is positioned on the atrial side of the prosthesis. Permanent pacing leads can be placed across a bio-prosthetic tricuspid valve without too much difficulty.
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