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The reliability of cardiogenic impedance and correlation with echocardiographic and plethysmographic parameters for predicting CRT time intervals post implantation
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Cardiology-Arrhythmia. (Carina Blomström Lundqvist)
St Thomas Hospital, London. (Matthew)
St Jude Med, Jarfalla, Sweden.
St Jude Med, Jarfalla, Sweden.
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2013 (English)In: Journal Of Interventional Cardiac Electrophysiology, ISSN 1383-875X, Vol. 37, no 2, 155-162 p.Article in journal (Refereed) Published
Abstract [en]

Aims

Encouraging data have been reported on the use of cardiogenic impedance (CI) in cardiac reshynchronization therapy (CRT) optimization. The purpose of this study was to: evaluate the stability of certain CI vectors 24 hours post implantation, study the correlation between these CI signals and selected echocardiographic parameters, examine the possibility of non-invasive calibration of patient-specific impedance-based prediction models.

Methods and results

Thirteen patients received a CRT-D device with monitor capability of the dynamic impedance between several electrodes. At implantations patient-specific impedance-based prediction models were created for identification of optimal atrioventricular (AV) and interventricular (VV) delays and calibrated on invasive measurements of left ventricular contractility (LV dP/dtmax). Simultaneously non-invasive measurements of LV dP/dtmax and stroke volume (SV) were obtained using a finger plethysmograph. Patients were re-evaluated with echocardiography and new CI measurements the day after implantation.The haemodynamic benefit achieved by optimal VV setting according to the patient-specific impedance-based prediction models at follow-up was not as large as the one obtained at implantation. In a multivariate partial least square regression analysis a correlation was found between aortic VTI and a generic linear combination of CI features (P<0,005). No correlation was found between the patient-specific impedance-based prediction models and the non-invasive measurements of LV dP/dtmax and SV.

Conclusions

Cardiogenic impedance signals can be used to optimize CRT settings but seems less feasible as an ambulatory tool since calibration is required. The positive correlation between aortic-VTI and CI measurements seems promising; although a larger cohort is required to create an echocardiography-based patient-specific model.

Place, publisher, year, edition, pages
2013. Vol. 37, no 2, 155-162 p.
Keyword [en]
cardiac resynchronization therapy, cardiogenic impedance, device optimization
National Category
Cardiac and Cardiovascular Systems
Identifiers
URN: urn:nbn:se:uu:diva-179547DOI: 10.1007/s10840-013-9795-5ISI: 000321268700005PubMedID: 23625092OAI: oai:DiVA.org:uu-179547DiVA: diva2:546246
Available from: 2012-08-22 Created: 2012-08-19 Last updated: 2016-08-11Bibliographically approved
In thesis
1. Cardiac Resynchronization Therapy Optimization: Comparison and Evaluation of Non-invasive Methods
Open this publication in new window or tab >>Cardiac Resynchronization Therapy Optimization: Comparison and Evaluation of Non-invasive Methods
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The general purpose of this thesis was to investigate new cardiac resynchronization therapy (CRT) optimization techniques and to assess their reliability when compared to invasive measurements of left ventricular contractility (LV dP/dtmax).We first assessed whether cardiac output (CO) measured by trans-thoracic impedance cardiography could correctly identify the optimal interventricular (VV) pacing interval while using invasive measurements of LV dP/dtmax as reference. We did not find any significant statistical correlation between the two optimizing methods when their corresponding optimal VV intervals were compared.

We also tested the hypothesis that measurements of right ventricular contractility (RV dP/dtmax) could be used to guide VV delay optimization in CRT. The comparison of optimal VV intervals obtained from the left and right ventricular dP/dtmax did not show a statistically significant correlation; however, a positive correlation was found when broader VV intervals were evaluated and we concluded that this finding deserves further investigation.

An interesting alternative for CRT optimization is the use of device integrated algorithms or sensors capable to adapt the CRT settings to the current needs of the individual patient. In this respect we investigated the use of cardiogenic impedance (CI) measurements obtained through the CRT-D device as a method for CRT optimization with invasive measurements of LV dP/dtmax as a reference. Our results showed that CI could be measured through the device after implantation and that a patient-specific impedance-based prediction model was capable to accurately predict the optimal AV and VV delays. To follow up on these positive results we re-evaluated the patient-specific impedance-based prediction models 24 hours post implantation and investigated the possibility of calibrating them using parameters derived from non-invasive measurements of arterial pressure obtained by finger pelthysmography at implantation.The results showed that the patient-specific impedance-based prediction models did not perform as well on the follow-up data as they did on the data from implantation day and that they correlated poorly with plethysmographic parameters.

Our studies suggest that novel methods for CRT optimization should be thoroughly evaluated and compared to established measures of left ventricular function prior to introduction into clinical practice.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2012. 52 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 802
Keyword
cardiac resynchronization therapy, device optimization, left ventricular contractility
National Category
Cardiac and Cardiovascular Systems
Research subject
Cardiology
Identifiers
urn:nbn:se:uu:diva-179785 (URN)978-91-554-8450-7 (ISBN)
Public defence
2012-10-05, Robergsalen, Akademiska Sjukhuset, Ing. 40, Uppsala, 13:00 (English)
Opponent
Supervisors
Available from: 2012-09-14 Created: 2012-08-22 Last updated: 2013-01-22Bibliographically approved

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