Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Cardiac Resynchronization Therapy Optimization: Comparison and Evaluation of Non-invasive Methods
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Cardiology-Arrhythmia. (Blomström Lundqvist)
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 [en]
cardiac resynchronization therapy, device optimization, left ventricular contractility
National Category
Cardiac and Cardiovascular Systems
Research subject
Cardiology
Identifiers
URN: urn:nbn:se:uu:diva-179785ISBN: 978-91-554-8450-7 (print)OAI: oai:DiVA.org:uu-179785DiVA: diva2:546247
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
List of papers
1. The use of impedance cardiography for optimizing the interventricular stimulation interval in cardiac resynchronization therapy-a comparison with left ventricular contractility
Open this publication in new window or tab >>The use of impedance cardiography for optimizing the interventricular stimulation interval in cardiac resynchronization therapy-a comparison with left ventricular contractility
Show others...
2009 (English)In: Journal of interventional cardiac electrophysiology (Print), ISSN 1383-875X, E-ISSN 1572-8595, Vol. 25, no 3, 223-228 p.Article in journal (Refereed) Published
Abstract [en]

The present study aimed to assess whether impedance cardiography (IC) can correctly identify the optimal interventricular (VV) pacing interval in cardiac resynchronization therapy (CRT). Twenty four patients received a biventricular pacemaker and underwent IC for cardiac output (CO) measurements to identify the optimal VV interval. Invasive measurements of left ventricular (LV) dP/dt(max) were used as a reference. During optimization the VV interval was changed with 20 ms steps from +80 (LV pre-excitation) to-80 ms (RV pre-excitation). The optimal VV interval was defined as the one that resulted in the highest LV dP/dt(max) value and the highest CO obtained by IC, respectively. During simultaneous biventricular pacing both LV dP/dt(max) and CO increased (mean 16.6% and 16.2%, respectively) as compared to baseline. Biventricular pacing with optimized VV intervals resulted in a further absolute increase of LV dP/dt (max) and CO (5.6% and 41.3%, respectively). The average decrease in LV dP/dt(max) was 79.6 +/- 51.6 mmHg/s when the optimal VV interval was programmed according to the IC measurements. Cross spectral analysis showed no correlation between the optimal VV intervals identified by the two methods (p > 0.05) and identical optimal VV intervals were identified in only six of the 24 patients. When broader VV time intervals were compared the correlation between the two methods was statistically significant (p = 0,0166). In conclusion, the use of IC for VV interval optimization is questionable since these optimized time intervals do not seem to correlate well with those obtained by measuring LV dP/dt.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:uu:diva-103115 (URN)10.1007/s10840-009-9367-x (DOI)000268581800013 ()19263200 (PubMedID)
Available from: 2009-05-14 Created: 2009-05-14 Last updated: 2013-01-22Bibliographically approved
2. Right ventricular contractility as a measure of optimal interventricular pacing setting in cardiac resynchronization therapy
Open this publication in new window or tab >>Right ventricular contractility as a measure of optimal interventricular pacing setting in cardiac resynchronization therapy
Show others...
2009 (English)In: Europace, ISSN 1099-5129, E-ISSN 1532-2092, Vol. 11, no 11, 1496-1500 p.Article in journal (Refereed) Published
Abstract [en]

AIMS: The aim of the present study was to assess whether right ventricular (RV) contractility can be used for optimization of the interventricular (VV) interval and to study the acute hemodynamic effect of different VV intervals on right and left ventricular (LV) contractility in patients referred for cardiac resynchronization therapy (CRT). METHODS AND RESULTS: Intracardiac LV and RV dP/dt were measured with a 0.014-in. sensor-tipped pressure guidewire during pacing at nine different VV intervals ranging from +80 ms (LV pre-excitation) to -80 ms (RV pre-excitation) in 26 patients who received a biventricular pacemaker. No correlation was found between the optimal VV intervals identified by maximum LV dP/dt and RV dP/dt, which were identical in only seven cases (27%). Only when testing slightly broader intervals (+/-20 ms) was there a statistically significant correlation (P= 0.037) between the optimized VV intervals. In the majority of patients (58%) either LV or RV pre-excitation was superior to simultaneous pacing according to LV dP/dt(max) measurements. CONCLUSION: RV dP/dt(max) failed to identify the optimal VV interval when compared with LV dP/dt(max) and can therefore not be recommended for VV optimization in CRT patients.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:uu:diva-123724 (URN)10.1093/europace/eup288 (DOI)000271388700019 ()19812048 (PubMedID)
Available from: 2010-04-29 Created: 2010-04-29 Last updated: 2017-12-12Bibliographically approved
3. Relationship between intracardiac impedance and left ventricular contractility in patients undergoing cardiac resynchronization therapy
Open this publication in new window or tab >>Relationship between intracardiac impedance and left ventricular contractility in patients undergoing cardiac resynchronization therapy
Show others...
2011 (English)In: Europace, ISSN 1099-5129, E-ISSN 1532-2092, Vol. 13, no 7, 984-991 p.Article in journal (Refereed) Published
Abstract [en]

Aims Cardiac resynchronization therapy (CRT) has dramatically improved the symptoms and prognosis of patients with heart failure in large randomized clinical trials. Optimization of device settings may maximize benefit on an individual basis, although the best method for this is not yet established. We evaluated the use of cardiogenic impedance measurements (derived from intracardiac impedance signals) in CRT device optimization, using invasive left ventricular (LV) dP/dt(max) as the reference. Methods and results Seventeen patients underwent invasive haemodynamic assessment using a pressure wire placed in the LV cavity at the time of CRT device implantation. Intracardiac impedance measurements were made at different atrioventricular (AV) and interventricular (VV) delays and compared with LV dP/dt(max). We assessed the performance of patient-specific and generic impedance-based models in predicting acute haemodynamic response to CRT. In two patients, LV catheterization with the pressure wire was unsuccessful and in two patients LV lead delivery was unsuccessful; therefore, data were acquired for 13 out of 17 patients. Left ventricular dP/dt(max) was 919 +/- 182 mmHg/s at baseline and this increased acutely (by 24%) to 1121 +/- 226 mmHg/s as a result of CRT. The patient-specific impedance-based model correctly predicted the optimal haemodynamic response (to within 5% points) for AV and VV delays in 90 and 92% of patients, respectively. Conclusion Cardiogenic impedance measurements are capable of correctly identifying the maximum achievable LV dP/dt(max) as measured by invasive haemodynamic assessment. This study suggests that cardiogenic impedance can potentially be used for CRT optimization and may have a role in ambulatory assessment of haemodynamics.

Keyword
Cardiac resynchronization therapy, Cardiogenic impedance, Device optimization, Haemodynamics
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:uu:diva-156251 (URN)10.1093/europace/eur055 (DOI)000292317900015 ()
Available from: 2011-07-19 Created: 2011-07-18 Last updated: 2017-12-08Bibliographically approved
4. The reliability of cardiogenic impedance and correlation with echocardiographic and plethysmographic parameters for predicting CRT time intervals post implantation
Open this publication in new window or tab >>The reliability of cardiogenic impedance and correlation with echocardiographic and plethysmographic parameters for predicting CRT time intervals post implantation
Show others...
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.

Keyword
cardiac resynchronization therapy, cardiogenic impedance, device optimization
National Category
Cardiac and Cardiovascular Systems
Identifiers
urn:nbn:se:uu:diva-179547 (URN)10.1007/s10840-013-9795-5 (DOI)000321268700005 ()23625092 (PubMedID)
Available from: 2012-08-22 Created: 2012-08-19 Last updated: 2016-08-11Bibliographically approved

Open Access in DiVA

fulltext(2372 kB)861 downloads
File information
File name FULLTEXT01.pdfFile size 2372 kBChecksum SHA-512
eda37233def6333ee525c52298895422693dd07d9babf03847b074f8f03a6e70bb17ca46b9d2e1341628256a44ef5813f85ac65c160138bbdd386206a0d7060b
Type fulltextMimetype application/pdf