Effects Of Atrioventricular Delay Research Articles

Effects of AV Delay and VV Delay on Left Atrial Pressure and Waveform in Ambulant Heart Failure Patients: Insights into CRT Optimization

We hypothesized that left atrial pressure (LAP) obtained by a permanent implantable sensor is sensitive to changes in cardiac resynchronization therapy (CRT) settings and could guide CRT optimization to improve the response rate. We investigated the effect of CRT optimization on LAP and its waveform parameters in ambulant heart failure (HF) patients. CRT optimization was performed in eight ambulant HF patients, using echocardiography as reference. LAP waveform was acquired at each of eight atrioventricular (AV) intervals and five inter-ventricular (VV) intervals. Selected waveform parameters were also evaluated for their sensitivity to CRT changes and agreement with echocardiography-guided optimal settings. Optimal AV and VV intervals varied considerably between patients. All patients exhibited significant changes in waveform morphology with AV optimization. Optimal AV delay determined from echocardiography ranged between 140 ms and 225 ms. Mean LAP tended to be lower at optimal setting 14 ± 3 mmHg compared to shorter (<100 ms) or longer (>160 ms) AV settings (P = 0.16). There were clear trends to smaller peak a-wave (P = 0.11) and gentler positive a-slope (P = 0.15) and positive v-slope (P = 0.09) with longer AV delays. Mean LAP and negative v-wave slope correlated well with echo-guided optimal setting, r = 0.91 (P = 0.001) and 0.79 (P = 0.03), respectively. No significant effects on LAP or waveform were seen during VV optimization. LAP and its waveform changes considerably with AV optimization. There is good agreement between echo-guided optimal setting and LAP. LAP could provide an objective guide to CRT optimization. (Clinical Trial Registry information: URL: http://www.clinicaltrials.gov. Unique Identifier: NCT00632372).

Fast Multiscale Modeling of Cardiac Electrophysiology Including Purkinje System

In this paper, we present a modeling methodology to couple the cardiac conduction system to cardiac myocytes through a model of Purkinje-ventricular junctions to yield fast and realistic electrical activation of the ventricles. A patient-specific biventricular geometry is obtained from processing computed tomography scan data. A one-manifold implementation of the fast marching method based on Eikonal-type equations is used for modeling heart electrophysiology, which facilitates the multiscale 1-D-3-D coupling at very low computational costs. The method is illustrated in in-silico experiments where we analyze and compare alternative pacing strategies on the same patient-specific anatomy. We also show very good agreement between the results from the proposed approach and more detailed and comprehensive biophysical models for modeling cardiac electrophysiology. The effect of atrioventricular delay on the distribution of activation time in myocardium is studied with two experiments. Given the reasonable computational times and realistic activation sequences provided by our method, it can have an important clinical impact on the selection of optimal implantation sites of pacing leads or placement of ablation catheter's tip in the context of cardiac rhythm management therapies.

Effects of Atrio-ventricular Delay and Interventricular Delay on Continuous left Atrial Pressure and Waveforms in Ambulant Heart Failure Patients: A Novel Method for Cardiac Resynchronisation Therapy Optimization

(62% in week one and 67% in week two), atrial arrhythmia (114% and 89%) and heart failure (44% and 67%). There was a dramatic surge of stress cardiomyopathy, especially following the second earthquake (none in 2009, six cases in the first two weeks following the 2010 earthquake and 24 cases in the first week of the 2011 earthquake). More data are currently been gathered and analysed following the 2011 earthquake. Conclusion: We have demonstrated significant increases in acute cardiology admissions following both earthquakes. This finding has important implications for future disaster planning. may be helpful for CRT optimisation. We evaluated the effect of changes in atrio-ventricular delay (AVD) and inter-ventricular delay (VVD) on LAP and its waveform morphology using a novel implantable LAP sensor. Methods: Eight ambulant patients (age 66± 12 yrs, EF 30± 10%) implanted with separate CRT-D and a new LAP monitoring system (PROMOTETM RF and HeartPODTM ISL, both from St. Jude Medical) underwent CRT optimization with echocardiographic guidance including transmitral and left ventricular outflow tract Doppler indices. LAP and intracardiac electrogramswere recorded at eight AVDs and five VVDs. Each LAP recording was 20 seconds long and was band-pass filtered to remove both high-frequency noise and respiration artifact. QRStriggered ensemble average waveforms were calculated for each recording and plotted to evaluate the effects of the different AVDs and VVDs on the LAP waveform. Results: Mean LAPs were lower in the more optimal echocardiography guided settings. All patients exhibited a dramatic response in waveform morphology to the changes in AVD (see figure) with the c-wave moving progressively into the a-wave and producing large cannon a-waves with shorter, less optimal AVD. VVD changes produced a less dramatic effect on LAP morphology. The effects were consistent between patients, with individual patient signals correlating closely with the mean population signal r= 0.80± 0.14. doi:10.1016/j.hlc.2011.03.019 Effects of Atrio-ventricular Delay and Interventricular Delay on Continuous left Atrial Pressure and Waveforms in Ambulant Heart Failure Patients: A Novel Method for Cardiac Resynchronisation Therapy Optimization W. Chan1,∗, A. Blomqvist 2, I. Melton1, K. Noren2, R.I. Crozier 1, Troughton1 1 Christchurch Hospital, New Zealand 2 St. Jude Medical AB, Sweden Background: Left atrial pressure (LAP) is sensitive to cardiac resynchronisation therapy (CRT) device settings and Conclusion: LAP and its waveformmorphology are sensitive to the effects of AVD and VVD in a consistent manner across patients. Further investigation of the role of LAP in CRT interval optimisation is warranted. A B S T R A C T S Heart, Lung and Circulation 379 2011;20:376–419 Abstracts

Effects of Atrio-Ventricular Delay and Interventricular Delay on Continuous Left Atrial Pressure and Waveforms in Ambulant Heart Failure Patients: A Novel Method for Cardiac Resynchronisation Therapy Optimisation

Background: Left atrial pressure (LAP) is sensitive to cardiac resynchronisation therapy (CRT) device settings and may be helpful for CRT optimisation. We evaluated the effect of changes in atrio-ventricular delay (AVD) and inter-ventricular delay (VVD) on LAP and its waveform morphology using a novel implantable LAP sensor. Methods: Eight ambulant patients (age 66 ± 12 yrs, EF 30 ± 10%) implanted with separate CRT-D and a new LAP monitoring system (PROMOTE™ RF and HeartPOD™ ISL, both from St Jude Medical) underwent CRT optimization with echocardiographic guidance including transmitral and left ventricular outflow tract Doppler indices. Left atrial pressure and intracardiac electrograms were recorded at eight AVDs and five VVDs. Each LAP recording was 20 seconds long and was band-pass filtered to remove both high-frequency noise and respiration artifact. QRS-triggered ensemble average waveforms were calculated for each recording and plotted to evaluate the effects of the different AVDs and VVDs on the LAP waveform. Results: Mean LAPs were lower in the more optimal echocardiography guided settings. All patients exhibited a dramatic response in waveform morphology to the changes in AVD with the c-wave moving progressively into the a-wave and producing large cannon a-waves with shorter, less optimal AVD. Inter-ventricular delay changes produced a less dramatic effect on LAP morphology. The effects were consistent between patients, with individual patient signals correlating closely with the mean population signal r = 0.80 ± 0.14. Conclusion: Left atrial pressure and its waveform morphology are sensitive to the effects of AVD and VVD in a consistent manner across patients. Further investigation of the role of LAP in CRT interval optimisation is warranted.

Effects of Atrioventricular Delay in Patients with DDD Pacemaker and Normal Systolic Function

Effects of Atrioventricular Delay in Patients with DDD Pacemaker and Normal Systolic Function