Noritaka Toda

Doppler Index and Plasma Level of Atrial Natriuretic Hormone Are Improved by Optimizing Atrioventricular Delay in Atrioventricular Block Patients with Implanted DDD Pacemakers

TODA, N., et al.: Doppler Index and Plasma Level of Atrial Natriuretic Hormone Are Improved by Optimizing Atrioventricular Delay in Atrioventricular Block Patients with Implanted DDD Pacemakers. Doppler index is the sum of isovolumetric contraction time and isovolumetric relaxation time divided by ejection time and has clinical value as an index of combined systolic and diastolic myocardial performance. This crossover study compared the Doppler index and atrial natriuretic hormone (atrial natriuretic peptide) [ANP] between optimal (AV) delay and prolonged AV delay in patients with DDD pacemakers. The study included 14 patients (6 men, 8 women, age 78.4 ± 9.3 [SD] years) with AV block with an implanted DDD pacemaker. AV delay was prolonged in a 25‐ms, stepwise fashion starting from 125 ms to 250 ms. Pacing rate was set at 70 beats/min. Cardiac output (CO) was assessed by pulsed Doppler echocardiography, and optimal AV delay was defined as the AV delay at which CO was maximum, and an AV delay setting of 250 ms as prolonged AV delay. Plasma level of ANP and Doppler index determined by echocardiography were measured 1 week after programming. AV delay was switched to another AV delay and measurements were repeated after 1 week. Optimal AV delay was 159 ± 19 ms. Doppler index was significantly lower at optimal AV delay than at prolonged AV delay (0.68 ± 0.26 vs 0.92 ± 0.30, P < 0.05). The plasma ANP level was significantly lower at optimal AV delay than at prolonged AV delay (29.0 ± 30.7 vs 52.6 ± 44.9 pg/mL, P < 0.05). In conclusion, the Doppler index and the plasma ANP level were significantly lower at optimal AV delay than at prolonged AV delay. This study shows the importance of the optimal AV delay setting in patients with an implanted DDD pacemaker, the Doppler index and plasma ANP levels are good indicators for optimizing AV delay.

Optimal Atrioventricular Delay Setting Determined by QT Sensor of Implanted DDDR Pacemaker

ISHIKAWA, T., et al.: Optimal Atrioventricular Delay Setting Determined by QT Sensor of Implanted DDDR Pacemaker. QT interval (QTI) may change when cardiac function is improved by optimizing the AV delay. QTI is used as the sensor for rate responsive pacemakers. Evoked (e)QTI is measured as the time duration from the ventricular pace‐pulse to the T sense point, which is the steepest point of the intracardiac T wave. The relationship between AV delay and eQTI and cardiac function was studied in 13 patients (74.2 ± 9.3 [SD] years old) with an implanted QT‐driven DDDR pacemaker. A special pacemaker software module was downloaded into the pacemaker memory for eQTI data logging. AV delay was set at 100, 120, 150, 180, 210, and 240 ms. Cardiac output (CO) was measured by continuous Doppler echocardiography. eQTI was 343.3 ± 22.4, 345.1 ± 22.5, and 343.4 ± 23.2 ms (P < 0.01, repeated ANOVA) and CO was 4.2 ± 0.8, 4.6 ± 0.8, and 4.2 ± 0.8 L/min (P < 0.0001, repeated ANOVA) when AV delay was set at the AV delay shortened by one step (AV[−]) and prolonged by one step (AV[+]) from the AV delay at which QT interval was maximum (AV[max]) in seven patients, in whom the peak AV delay at which the eQTI was maximal could be identified. eQTI decreased from 341.1 ± 20.9 to 339.4 ± 21.1 ms (P < 0.0001) and CO decreased from 4.4 ± 1.4 to 4.1 ± 1.3 L/min (P < 0.005) when AV delay was prolonged from AV(max) to AV(+) in all patients. eQTI decreased from 345.1 ± 22.5 to 343.3 ± 22.4 ms (P < 0.0005) and CO decreased from 4.6 ± 0.8 to 4.2 ± 0.8 L/min (P < 0.05) when AV delay was shortened from AV(max) to AV(−) in seven patients. Thus, CO was maximal when AV delay was set at the AV delay at which eQTI was maximal. In conclusion, the optimal AV delay can be predicted from the eQTI sensed by an implanted pacemaker, and automatic setting of the optimal AV delay can be achieved by the QT sensor of an implanted pacemaker.

Long-term effect of cardiac pacing on sleep-disordered breathing in patients with conventional indications for a permanent pacemaker

The effect of cardiac pacing on sleep‐disordered breathing is controversial. We investigated the long‐term effect of cardiac pacing on sleep disordered breathing in patients with conventional indications for permanent pacemakers