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Ventricular Depolarisation Variation in Sinus and Premature Ventricular Complexes (PVC)
243 Ventricular Depolarisation Variation in Sinus and Premature Ventricular Complexes (PVC) B. Shi 1,2,∗ , S. Harding 1,3 , A. Jimenez 1,3 , P. Larsen 1,2 1 Wellington
Cardiovascular Research Group, New Zealand of Otago Wellington, New Zealand 3 Wellington Regional Hospital, New Zealand 2 University
Background: Ventricular re-entrant arrhythmias are commonly initiated by PVCs. The initiation of arrhythmia is partly dependent on the timing of the PVCs. In addition, the spatial variation of depolarisation associated with PVCs may also be critical in the initiation of reentry, as greater spatial variation is more likely to promote conduction block. However the extent to which spatial variation of depolarisation differs in PVCs compared to sinus beats, or between PVCs of different morphology is unknown. Methods and results: Spatial variation in depolarisation can be characterised by absolute (QRSabs) and relative (QRSrel) QRS non-dipolar components derived from 12lead ECG using singular value decomposition analysis. In 85 patients receiving ICD implants with an average of 7 ± 8 PVCs over 60 s, we found that QRSabs and QRSrel were larger in PVCs than in sinus beats (0.47 ± 0.58 mV2 vs. 0.21 ± 0.25 mV2 , p < 0.0001; 0.54 ± 0.57% vs. 0.31 ± 0.34%, p < 0.0001) indicating greater spatial variation in depolarisation. In 44 patients with multifocal PVCs (2–9 morphologies), we observed in some patients little change in spatial variation between different morphologies, while in others spatial variation was markedly different between morphologies (Coefficient of variation of QRSabs ranged from 7 to 104% and QRSrel ranged from 3 to 113%). Conclusion: PVCs exhibited greater spatial variation of depolarisation than sinus beats and multifocal PVCs from the same patient in some cases exhibited highly variable levels of spatial depolarisation variability. Therefore, the probability of initiating reentry may vary significantly between different PVCs. The utility of characterising PVCs for arrhythmic risk stratification is under investigation.
CSANZ 2013 Abstracts
S103
isation is a product of conduction velocity, length of the reentrant circuit, and the extent to which this circuit changes on a cycle to cycle basis. In this study we examined the relationship between these properties and structural properties of the ventricle. Methods: 12 lead VF was recorded during ICD implant testing in patients who had a pre-implant MRI. VF was analysed to derive the dominant frequency (DF), bandwidth, proportion of power at DF, sample entropy and autocorrelation peak. These characteristics were related to the presence of scar, LVEF, LVEDV and LVESV derived from MRI. Results: In 23 patients, nine had ischaemic scar and six had non-ischaemic scar. Significantly slower VF was observed (lower DF) in the presence of scar (DF 5.0 Hz vs 5.7 Hz in those without scar, p = 0.0251), mainly due to the ischaemic group (mean DF 4.8 Hz). Significant correlations were found between DF and LVEF (r = 0.60, p = 0.0026), and inverse correlations between DF and LVEDV (r = −0.59, p = 0.0029) and DF and LVESV (r = −0.60, p = 0.0026) that could not be entirely accounted for on the basis of scar characteristics. Other statistical measures of VF were not correlated to structural measures. Conclusion: Slower VF was seen in patients with ischaemic scar, possibly due to either longer reentrant pathways or slow conduction in the scar border zone, and in patients with increased with ventricular size where longer reentrant pathways may exist. Other VF characteristics appear to be less related to ventricular structure. http://dx.doi.org/10.1016/j.hlc.2013.05.245 Electrophysiology – Clinical Devices, Mapping & Ablation 245 A Comparison of Right Ventricular Apical (RVA) and NonApical (RVNA) Defibrillator (ICD) Lead Position: A Single Centre Experience L. Eng ∗ , B. Hunt, K. Dauber, J. Hill, P. Gould, G. Kaye Princess Alexandra Hospital, Australia
http://dx.doi.org/10.1016/j.hlc.2013.05.244 244 VF Frequency is Influenced by Cardiac Structure E. Woodcock 1,2,∗ , S. Harding 3 , B. Shi 1 , N. Lever 4 , P. Larsen 1 1 Department of Surgery and Anaesthesia, University of Otago,
Wellington, New Zealand 2 Cardiology Department, Christchurch Hospital, Christchurch,
New Zealand 3 Cardiology
Department, Wellington Hospital, Wellington, New Zealand 4 Greenlane Cardiovascular Service, Auckland Hospital, Auckland, New Zealand Background: Ventricular fibrillation (VF) waveforms have a high level of underlying organisation. This organ-
There is little data on long term effectiveness on RVNA vs RVA ICD lead position. Objective: To investigate ICD lead stability and efficacy of delivered therapy between RVNA and RVA positions. Methods: We conducted a retrospective review of 512 patients who received an ICD at our institution from 1999 to 2011. A comparison of demographic and baseline characteristics, lead impedance, sensing and pacing threshold, and device therapies was performed between leads at RVNA and those at RVA. Results: The two groups had similar baseline demographic and clinical characteristics. The average follow up period in the RVNA cohort was 40.4 ± 25.9 months and in the RVA was 38 ± 31.8 months (p = 0.43). No significant difference was detected in the proportion of patients receiving an appropriate ICD defibrillation (RVNA 10.4% vs. RVA 16.8%; p = 0.07), inappropriate defibrillation (RVNA 7.6% vs. RVA 7.6%; p = 0.99) or
ABSTRACTS
Heart, Lung and Circulation 2013;22:S1–S125
Cardiovascular Research Group, New Zealand of Otago Wellington, New Zealand 3 Wellington Regional Hospital, New Zealand 2 University
Background: Ventricular re-entrant arrhythmias are commonly initiated by PVCs. The initiation of arrhythmia is partly dependent on the timing of the PVCs. In addition, the spatial variation of depolarisation associated with PVCs may also be critical in the initiation of reentry, as greater spatial variation is more likely to promote conduction block. However the extent to which spatial variation of depolarisation differs in PVCs compared to sinus beats, or between PVCs of different morphology is unknown. Methods and results: Spatial variation in depolarisation can be characterised by absolute (QRSabs) and relative (QRSrel) QRS non-dipolar components derived from 12lead ECG using singular value decomposition analysis. In 85 patients receiving ICD implants with an average of 7 ± 8 PVCs over 60 s, we found that QRSabs and QRSrel were larger in PVCs than in sinus beats (0.47 ± 0.58 mV2 vs. 0.21 ± 0.25 mV2 , p < 0.0001; 0.54 ± 0.57% vs. 0.31 ± 0.34%, p < 0.0001) indicating greater spatial variation in depolarisation. In 44 patients with multifocal PVCs (2–9 morphologies), we observed in some patients little change in spatial variation between different morphologies, while in others spatial variation was markedly different between morphologies (Coefficient of variation of QRSabs ranged from 7 to 104% and QRSrel ranged from 3 to 113%). Conclusion: PVCs exhibited greater spatial variation of depolarisation than sinus beats and multifocal PVCs from the same patient in some cases exhibited highly variable levels of spatial depolarisation variability. Therefore, the probability of initiating reentry may vary significantly between different PVCs. The utility of characterising PVCs for arrhythmic risk stratification is under investigation.
CSANZ 2013 Abstracts
S103
isation is a product of conduction velocity, length of the reentrant circuit, and the extent to which this circuit changes on a cycle to cycle basis. In this study we examined the relationship between these properties and structural properties of the ventricle. Methods: 12 lead VF was recorded during ICD implant testing in patients who had a pre-implant MRI. VF was analysed to derive the dominant frequency (DF), bandwidth, proportion of power at DF, sample entropy and autocorrelation peak. These characteristics were related to the presence of scar, LVEF, LVEDV and LVESV derived from MRI. Results: In 23 patients, nine had ischaemic scar and six had non-ischaemic scar. Significantly slower VF was observed (lower DF) in the presence of scar (DF 5.0 Hz vs 5.7 Hz in those without scar, p = 0.0251), mainly due to the ischaemic group (mean DF 4.8 Hz). Significant correlations were found between DF and LVEF (r = 0.60, p = 0.0026), and inverse correlations between DF and LVEDV (r = −0.59, p = 0.0029) and DF and LVESV (r = −0.60, p = 0.0026) that could not be entirely accounted for on the basis of scar characteristics. Other statistical measures of VF were not correlated to structural measures. Conclusion: Slower VF was seen in patients with ischaemic scar, possibly due to either longer reentrant pathways or slow conduction in the scar border zone, and in patients with increased with ventricular size where longer reentrant pathways may exist. Other VF characteristics appear to be less related to ventricular structure. http://dx.doi.org/10.1016/j.hlc.2013.05.245 Electrophysiology – Clinical Devices, Mapping & Ablation 245 A Comparison of Right Ventricular Apical (RVA) and NonApical (RVNA) Defibrillator (ICD) Lead Position: A Single Centre Experience L. Eng ∗ , B. Hunt, K. Dauber, J. Hill, P. Gould, G. Kaye Princess Alexandra Hospital, Australia
http://dx.doi.org/10.1016/j.hlc.2013.05.244 244 VF Frequency is Influenced by Cardiac Structure E. Woodcock 1,2,∗ , S. Harding 3 , B. Shi 1 , N. Lever 4 , P. Larsen 1 1 Department of Surgery and Anaesthesia, University of Otago,
Wellington, New Zealand 2 Cardiology Department, Christchurch Hospital, Christchurch,
New Zealand 3 Cardiology
Department, Wellington Hospital, Wellington, New Zealand 4 Greenlane Cardiovascular Service, Auckland Hospital, Auckland, New Zealand Background: Ventricular fibrillation (VF) waveforms have a high level of underlying organisation. This organ-
There is little data on long term effectiveness on RVNA vs RVA ICD lead position. Objective: To investigate ICD lead stability and efficacy of delivered therapy between RVNA and RVA positions. Methods: We conducted a retrospective review of 512 patients who received an ICD at our institution from 1999 to 2011. A comparison of demographic and baseline characteristics, lead impedance, sensing and pacing threshold, and device therapies was performed between leads at RVNA and those at RVA. Results: The two groups had similar baseline demographic and clinical characteristics. The average follow up period in the RVNA cohort was 40.4 ± 25.9 months and in the RVA was 38 ± 31.8 months (p = 0.43). No significant difference was detected in the proportion of patients receiving an appropriate ICD defibrillation (RVNA 10.4% vs. RVA 16.8%; p = 0.07), inappropriate defibrillation (RVNA 7.6% vs. RVA 7.6%; p = 0.99) or
ABSTRACTS
Heart, Lung and Circulation 2013;22:S1–S125