Assessing Acute Ventricular Volume Changes by Intracardiac Impedance in a Chronic Heart Failure Animal Model

Stahl, Carsten; Walker, Tobias; Straub, Andreas; Kettering, Klaus; Knubben, K; Greiner, Tim O.; Paule, Stefan; Lippert, M.; Czygan, Gerald; Schweika, Oliver; Kühlkamp, Volker

doi:10.1111/j.1540-8159.2009.02477.x

Cited by 10 publications

(7 citation statements)

References 22 publications

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“…Stahl et al 17 showed a strong correlation between intracardiac impedance parameters and stroke volume in a porcine model. Panescu et al 18 examined multiple impedance vectors derived from implanted biventricular implantable cardioverter-defibrillator devices in a canine/ovine model of heart failure, and demonstrated good correlation between cardiogenic impedance and progression of heart failure.…”

Section: Discussionmentioning

confidence: 97%

“…Cardiogenic impedance reflects the volumetric fluctuations within the heart during the cardiac cycle and has been used to monitor cardiac contraction in an animal model. 17 This method therefore has the potential to be used for device optimization and may be performed using the device alone, without other specific equipment. Furthermore, as the impedance data are acquired from leads positioned within and on the surface of the heart, this technique should be more specific than the use of trans-thoracic impedance.…”

Section: Introductionmentioning

confidence: 99%

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Relationship between intracardiac impedance and left ventricular contractility in patients undergoing cardiac resynchronization therapy

et al. 2011

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AimsCardiac 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/dtmax as the reference.Methods and resultsSeventeen 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/dtmax. 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/dtmax 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.ConclusionCardiogenic impedance measurements are capable of correctly identifying the maximum achievable LV dP/dtmax 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.

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Section: Discussionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Relationship between intracardiac impedance and left ventricular contractility in patients undergoing cardiac resynchronization therapy

et al. 2011

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“…20 A positive correlation between LV impedance fluctuation and stroke volume and a negative correlation between diastolic impedance and pressure have been reported in animal experiments using LV electrodes placed on the epicardial surface, outside the cardiac veins. 21–23 In other studies, quadripolar systems involving transvenous LV leads have been applied for impedance recording between RV and LV. 24,25 In these cases, however, it is impossible to tell if the transventricular impedance signal reflects the activity of the LV, RV, or both.…”

Section: Discussionmentioning

confidence: 99%

Left ventricular mechanical activity detected by impedance recording

et al. 2010

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AimsRecording and analysing impedance fluctuation along the cardiac cycle in the right (RV) and left ventricles (LV).Methods and resultsDuring a biventricular (BiV) implantation procedure, impedance was sequentially derived between the atrial ring electrode and either electrode (tip or ring) of the RV lead [transvalvular impedance (TVI)], and between the atrial ring and either the tip or ring electrode of a coronary sinus lead, positioned in a cardiac vein [left ventricle impedance (LVI)]. The LVI signal was also recorded by the implanted pacemaker at the 1 day and 3 months follow-ups. With intrinsic conduction, TVI showed an average increase of 53 ± 29 Ω during ventricular systole, whereas at the same time, LVI decreased by 45 ± 21 Ω (25 and 23 patients, respectively, out of 28 tested cases). Transvalvular impedance and LVI displayed a similar time course, which appeared to be related to the systolic timing in the RV and LV. Both LVI amplitude and duration decreased as a function of the cardiac rate. The LVI deflection started immediately after LV stimulation, and often anticipated the R-wave sensing after contralateral pacing. At the 3-month follow-up, LVI amplitude was decreased in 70% of cases and increased in the remainder, with a non-significant average change of −5 ± 85% with respect to the acute recordings.ConclusionTransvalvular impedance properties are consistent with the assumption of an inverse relationship with RV volume. Though LVI requires a different physical interpretation, the waveform duration might reflect the timing of LV myocardial contraction. In this hypothesis, the relationship between TVI and LVI could provide insight into the effects of BiV pacing on mechanical synchronization.

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“…In other animal models, intracardiac impedance measured between the LV and RV leads in a CRT platform has also been closely correlated with end-diastolic volume, end-diastolic pressure, 37 stroke volume, and LV dP/dt max . 38 Furthermore, in patients undergoing CRT device implantation, intracardiac impedance (LV-RV) is more closely correlated with echocardiographic changes in LV volume than intrathoracic impedance (RV-can). 39 These findings suggest that changes in LV volume and pressure conditions may produce a more profound change in impedance along the LV-RV vector, encompassing only cardiac tissue, as opposed to the RV-can vector, which encompasses a larger area of noncardiac tissue and may be less sensitive to minute changes in LV loading conditions.…”

Section: Merchant Et Al Implantable Sensors For Heart Failurementioning

confidence: 99%

Implantable Sensors for Heart Failure

Merchant

Dec

Singh

2010

Circ: Arrhythmia and Electrophysiology

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Assessing Acute Ventricular Volume Changes by Intracardiac Impedance in a Chronic Heart Failure Animal Model

Abstract: The strong correlation with SV allows the application of intracardiac impedance measurements for an implant-based continuous monitoring of cardiac function. Impedance may also be used for hemodynamic optimization of cardiac resynchronization therapy.

Cited by 10 publications

References 22 publications

Relationship between intracardiac impedance and left ventricular contractility in patients undergoing cardiac resynchronization therapy

Relationship between intracardiac impedance and left ventricular contractility in patients undergoing cardiac resynchronization therapy

Left ventricular mechanical activity detected by impedance recording

Implantable Sensors for Heart Failure

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