Optimized multisite ventricular pacing in postoperative single-ventricle patients

Pacing in Pediatric Patients with Postoperative Atrioventricular Block

Surgery for congenital heart disease may compromise atrioventricular (AV) nodal conduction, potentially resulting in postoperative AV block. In the majority of cases, AV nodal function recovers during the early postoperative period and may only require short-term pacing support, typically provided via temporary epicardial wires. Permanent pacing is indicated when the postoperative AV block persists for more than 7 to 10 days due to the risk of mortality if a pacemaker is not implanted. Although there is a subset of patients who may have late recovery of AV nodal function, those with continued postoperative AV block will need lifelong pacing therapy.

Techniques for Cardiac Resynchronization Therapy in Patients with Congenital Heart Disease

Cardiac resynchronization therapy (CRT) for congenital heart disease has shown promising suucess as an adjunct to medical therapy for heart failure. While cardiac conduction defects and need for ventricular pacing are common in congential heart disease, CRT indications, techniques and long term outcomes have not been well establaished. This is a review of the techniques nad short term outcomes of CRT for the following complex congenital heart disease conditions: single ventricle physiology, systemic right ventricle, and the subpulmonic right ventricle.

Ventricular function and dyssynchrony in children with a functional single right ventricle using real time three-dimensional echocardiography after fontan operation

BACKGROUND

This study aimed to evaluate the feasibility and clinical value of real time three-dimensional echocardiography (RT-3DE) for assessing ventricular systolic dysfunction and dyssynchrony in children with an functional single right ventricle (FSRV) having undergone the Fontan procedure.

METHODS

Twenty-five children with an FSRV and 25 healthy children were enrolled in our study. RV volume analysis was performed compared with magnetic resonance imaging (MRI) as the reference standard in FSRV patients. The patients were divided into wide and narrow QRS interval groups. Global and regional functions of the RV in three compartments (inflow, body, and outflow) were compared between FSRV and control subjects, including RV systolic dyssynchrony indices of maximal difference of time to minimal volume (Tmsv-Dif), standard deviation of time to minimal volume (Tmsv-SD), maximal difference of time to minimal volume corrected by R-R interval (Tmsv-Dif%), and standard deviation of time to minimal volume corrected by R-R interval (Tmsv-SD%).

RESULTS

RT-3DE measurements were significantly lower than MRI measurements for RV-EDV, RV-ESV, RV-SV, and RVEF (p < 0.01).Compared with controls, patients with an FRSV had significantly higher dyssynchrony indices and significantly lower global EF in both narrow QRS interval and wide QRS interval groups. Tmsv-SD% was shown to be most strongly correlated with MRI-RVEF (r = -.570, p = 0.003).

CONCLUSIONS

RT-3DE tended to underestimate RV ventricular volume in children with FSRV. Children with an FSRV and either a wide or narrow QRS interval had reduced ventricular function and higher dyssynchrony than normal subjects. Worsening RV dyssynchrony is associated with overall decline in function after the Fontan operation.

Right Ventricular Mechanical Dyssynchrony in Hypoplastic Left Heart Syndrome: Correlation with Systolic Function and QRS Duration

The single right ventricle (RV) in hypoplastic left heart syndrome (HLHS) often develops systolic dysfunction with time and this affects prognosis. Mechanical dyssynchrony has been reported in HLHS but has not consistently correlated with systolic function or electrical dyssynchrony. The aims of this study were to assess the relationship between RV mechanical dyssynchrony, RV systolic function, and QRS duration on surface electrocardiography. We hypothesized that surface QRS duration would not be an adequate indicator of mechanical dyssynchrony compared with dyssynchrony parameters. Retrospective analysis of echocardiograms of patients with HLHS divided into preserved vs reduced RV function. We measured two RV function parameters: (1) fractional area change (FAC) and (2) global longitudinal strain (RVGLS). We measured two dyssynchrony parameters: (1) the standard deviation of the time to peak strain for 9 segments (tPS-9) and (2) time difference between the earliest and latest time to peak strain (RV dyssynchrony index or RVDI) both corrected for R-R interval. We also measured the QRS duration from surface EKG. Mechanical dyssynchrony parameters were compared to both RV systolic function and to QRS duration. 41 patients with HLHS were identified: 21 had preserved function and 20 had reduced function defined by a FAC < 35%. The reduced function group had a significantly lower mean FAC and RVGLS. RVDI was higher in the dysfunction group and had a modest correlation with FAC (r = 0.48) and RVGLS (r = 0.57). tPS-9 was longer in the dysfunction group and had a modest correlation with FAC (r = 0.45) and RVGLS (r = 0.57). QRS duration was longer in the dysfunction group and had a modest correlation with FAC (r = 0.56) and RVGLS (r = 0.56). The weakest correlations were between QRS duration and tPS-9 (r = 0.32) and QRS duration and RVDI (r = 0.10). RV dysfunction measured by FAC was associated with mechanical dyssynchrony measured by increased RVDI and tPS-9. QRS duration was longer in the group with dysfunction but did not correlate with directly measured mechanical dyssynchrony. This may have potential implications for cardiac resynchronization therapy in univentricular patients as assessed by mechanical dyssynchrony parameters rather than QRS duration alone.

Cardiac Arrhythmias in Adults with Congenital Heart Disease: Pacemakers, Implantable Cardiac Defibrillators, and Cardiac Resynchronization Therapy Devices

Implanting cardiac rhythm medical devices in adults with congenital heart disease requires training in congenital heart disease. The techniques and indications for device implantation are specific to the anatomic diagnosis and state of disease progression. It often requires a team of physicians and is best performed at a specialized adult congenital heart center.

A Review of Surgical Atrioventricular Block with Emphasis in Patients with Single Ventricle Physiology

We perceived an increased incidence of surgical atrioventricular (AV) block in patients with single ventricle physiology undergoing two ventricle rehabilitation for hypoplastic left heart syndrome compared to the overall incidence of surgical AV block for our institution. Retrospective investigation of our center's data revealed a statistically significant increase in the incidence of surgical AV block in the single ventricle population and two ventricle rehabilitation population compared to the two ventricle population. Here we review the literature with respect to historic definitions, incidence, risk factors, pre- and post-op management, current indications for pacemaker placement and added cost and comorbidity associated with surgical AV block. We then offer possible strategies for decreasing the incidence of surgical AV block within both the single and two ventricle populations.