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[Delayed atrial excitation following bifocal pacemaker stimulation]
Insights
DDD pacemaker therapy effectively managed drug-resistant ventricular tachycardia in a patient with heart failure. Optimal results required personalized, prolonged atrioventricular intervals, demonstrating the need for individualized pacemaker settings.
Area of Science:
- Cardiology
- Biomedical Engineering
- Electrophysiology
Background:
- Drug-resistant ventricular tachycardia in ischemic heart disease with severe left ventricular failure presents a significant therapeutic challenge.
- Standard treatments often prove insufficient, necessitating advanced pacing strategies.
Observation:
- A patient with these conditions was treated with a DDD pacemaker system set at 90 beats/min for overdrive suppression.
- High-dose beta-blocker therapy was also administered.
- Electrocardiogram (ECG) revealed a 100 ms delay between the atrial spike and P-wave, indicating ineffective atrial contraction.
Findings:
- Hemodynamic effects of the ineffective atrial contraction were evaluated using various monitoring techniques.
- Positive effects of physiological pacing were achieved only by further prolonging the atrioventricular (AV) interval by 100 ms.
- This suggests that optimal AV intervals can vary significantly between individuals.
Implications:
- The study highlights that DDD pacemakers may require individually tailored, prolonged AV intervals for optimal physiological pacing.
- This finding is crucial for optimizing pacing modes like VAT, VDD, and DVI in specific patient cases.
- Individualized programming is key to maximizing the benefits of pacemaker therapy in complex cardiac conditions.
Abstract:
A patient with drug-resistant ventricular tachycardia due to ischemic heart disease with severe left ventricular failure was successfully treated by the implantation of a DDD pacemaker system pacing at a rate of 90 beats/min (overdrive suppression). Additional therapy with high doses of beta-blockers was necessary. The ECG demonstrated a delay of 100 ms between atrial spike and p-wave. The hemodynamic effects of this ineffective atrial contraction were assessed by jugular venous puls tracing, phonocardiography, echocardiography, and radionuclide-ventriculography. The desired positive effects of physiological pacing could only be achieved by further prolongation of the A-V interval by these 100 ms. This observation shows that, with DDD pacemakers, AV intervals of varying length may be necessary with VAT or VDD and DVI modes in individual cases.