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Sinus and atrioventricular nodal function: Preoperative and early postoperative assessment in children
Insights
Postoperative atrial pacing studies reveal that junctional recovery is a more reliable indicator of sinus node depression than sinus nodal recovery time. Atrioventricular node function assessment was unreliable, but nodal depression correlated with increased dysrhythmias.
Area of Science:
- Pediatric Cardiology
- Electrophysiology
- Cardiac Surgery
Background:
- Assessing sinus and atrioventricular (AV) nodal function pre- and post-cardiac surgery is crucial for understanding postoperative complications.
- Rapid atrial pacing is a common method to evaluate nodal function, but its reliability in the early postoperative period requires further investigation.
Purpose of the Study:
- To compare preoperative and early postoperative sinus and AV nodal function in children undergoing cardiac surgery.
- To identify reliable electrophysiological markers for detecting nodal dysfunction after surgery.
Main Methods:
- Ninety-three rapid atrial pacing studies were conducted in 38 children.
- Studies were performed preoperatively and within 48 hours and 4-8 days postoperatively.
- Sinus nodal recovery time (SNRT) and AV nodal function (Wenckebach cycle length) were assessed.
Main Results:
- SNRT was an unreliable index of sinus node depression due to inconsistent postoperative changes.
- Junctional recovery focus was a more definitive indicator of sinus node depression.
- AV nodal function assessment showed decreased function in 27% of studies, but the method was deemed unreliable.
- Nodal depression (sinus or AV) was strongly associated with a higher incidence of dysrhythmias (80-100% of affected patients).
Conclusions:
- Junctional recovery is a more reproducible marker for postoperative sinus node depression than SNRT.
- Standard electrophysiological tests for AV nodal function may be unreliable in the early postoperative period.
- Despite variability, sinus and AV nodal depression post-surgery significantly increases the risk of dysrhythmias.
Abstract:
Ninety-three rapid atrial pacing studies were performed in 38 children to compare preoperative and early postoperative function of the sinus and atrioventricular (AV) nodes. The interval between the preoperative and postoperative studies was under 6 months in the majority of patients. Postoperative studies were performed within 48 hours of operation and between 4 and 8 days after operation. Sinus nodal function as measured by sinus nodal recovery time (SNRT) was an unreliable index in determining depression since the number who improved postoperatively (10/55) was nearly equal to the number that worsened (12/55). The majority who had abnormal function postoperatively demonstrated a junctional rather than sinus recovery focus. This finding appears a more definitive and more reproducible indicator of sinus node depression in the postoperative patient. Postoperative AV nodal function was decreased (as measured by the cycle length [CL] at which Wenckebach periodicity occurred) in 15 of 55 studies (27%) of the entire group. There was nearly an equal chance for improvement (24%) in function. This also applied to those patients who had sequential studies. Therefore, this method of assessment for AV nodal function was unreliable, or else the operation did not affect the node significantly. The latter is unlikely in view of late postoperative data. The greatest utility of this test was to determine the capability for AV conduction in certain patients with slow escape rhythms in the absence of surface P waves, and to differentiate complete heart block from AV dissociation when atrial activity was absent. Despite the variability of effects on the sinus and AV nodes in these patients, those who demonstrated depression had a significantly higher incidence of dysrhythmias (80% of patients with sinus nodal depression and 100% of patients with AV nodal depression).