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Ventricular evoked response in patients with hypertrophic obstructive cardiomyopathy treated with DDD pacing
J R Sant'Anna1, R Prati, H Hutten
1Instituto de Cardiologia, Rio Grande do Sul/Fundação Universitária de Cardiologia, Porto Alegre, Brazil.
Insights
Dual-chamber (DDD) pacing significantly reduced the left ventricular outflow tract gradient (LVOTG) in hypertrophic obstructive cardiomyopathy (HOCM) patients. Intramyocardial electrograms effectively assessed these ventricular evoked responses (VER).
Area of Science:
- Cardiology
- Biomedical Engineering
- Medical Devices
Background:
- Hypertrophic obstructive cardiomyopathy (HOCM) is characterized by a significant left ventricular outflow tract gradient (LVOTG).
- Dual-chamber (DDD) pacing is a therapeutic option for managing drug-refractory HOCM.
- Ventricular evoked responses (VER) can provide insights into left ventricular dynamics.
Purpose of the Study:
- To evaluate the impact of decreasing LVOTG via DDD pacing on VER in HOCM patients.
- To determine the relationship between AV delay settings and changes in LVOTG and VER.
- To assess the utility of intramyocardial electrograms for monitoring left ventricular dynamics.
Main Methods:
- Implantation of a Physios CTM dual-chamber pulse generator in 9 severe HOCM patients.
- Sequential programming of AV delays (150 ms to 50 ms) to assess LVOTG and VER.
- Correlation analysis between LVOTG values and VER magnitude.
Main Results:
- DDD pacing significantly reduced mean LVOTG from 98 ± 22 mmHg to 59 ± 24 mmHg.
- AV delays > 100 ms resulted in a significantly lower decrease in VER depolarization duration (VERDD) compared to AV delays ≤ 100 ms.
- A significant correlation (r = 0.69; p < 0.05) was observed between LVOTG values and VER magnitude.
Conclusions:
- DDD pacing effectively reduces LVOTG in HOCM patients.
- AV delay programming influences VER and LVOTG.
- Intramyocardial electrograms are a sensitive tool for assessing left ventricular dynamics in HOCM patients undergoing DDD pacing.
Objective:
To assess the changes in ventricular evoked responses (VER) produced by the decrease in left ventricular outflow tract gradient (LVOTG) in patients with hypertrophic obstructive cardiomyopathy (HOCM) treated with dual-chamber (DDD) pacing.
Methods:
A pulse generator Physios CTM (Biotronik, Germany) was implanted in 9 patients with severe drug-refractory HOCM. After implantation, the following conditions were assessed: 1) Baseline evaluation: different AV delay (ranging from 150 ms to 50 ms) were sequentially programmed during 5 to 10 minutes, and the LVOTG (as determined by Doppler echocardiography) and VER recorded; 2) standard evaluation, when the best AV delay (resulting in the lowest LVOTG) programmed at the initial evaluation was maintained so that its effect on VER and LVOTG could be assessed during each chronic pacing evaluation.
Results:
LVOTG decreased after DDD pacing, with a mean value of 59 +/- 24 mmHg after dual chamber pacemaker, which was significantly less than the gradient before pacing (98 + 22 mmHg). An AV delay > 100 ms produced a significantly lower decrease in VER depolarization duration (VERDD) when compared to an AV delay < or = 100 ms. Linear regression analyses showed a significant correlation between the LVOTG values and the magnitude of VER (r = 0.69; p < 0.05) in the 9 studied patients.
Conclusion:
The telemetry obtained intramyocardial electrogram is a sensitive means to assess left ventricular dynamics in patients with HOCM treated with DDD pacing.