Strength Duration Curve for Epicardial Left Ventricular Stimulation

Scally, D O Monique; Heston, J R N Karen; Rudnick, Andrew; Deger, Florin T.; Greenberg, Richard M.

doi:10.1111/j.1540-8159.2007.00721.x

Cited by 7 publications

(10 citation statements)

References 4 publications

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Section: Discussionmentioning

confidence: 86%

“…The mean stimulation chronaxie of 0.15 ms for the lead tip and 0.23 ms for the coil are situated at the lower edge of the 0.2 ms to 0.6 ms chronaxie range reported for electrodes with a surface area from 2 mm 2 to 10 mm 2 . 30,[32][33][34][35][36] In historical data, amplitude resolution was limited, with the finest voltage step being 20% to 40% of rheobase. Strength-duration curves were usually reconstructed from 3 to 5 not-quite-exact data points, which introduced imprecision into the chronaxie extrapolation and spurred recent recommendations on how to improve the methodology.…”

Section: Comparison Of Our Results With the Literaturementioning

confidence: 99%

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A Comparison of Chronaxies for Ventricular Fibrillation Induction, Defibrillation, and Cardiac Stimulation: Unexpected Findings and Their Implications

Lawo

Deneke

Schrader

et al. 2009

Cardiovasc electrophysiol

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It may be reasonable to study whether LEC pulses from 0.25 ms to 0.30 ms in duration and up to 250 V in amplitude would increase therapeutic yield in VT termination without VF induction in humans. Contrary to the current belief, the discrepancy between defibrillation and stimulation chronaxie is not caused by different electrode size. We postulate that the time constant of the fast sodium channel reactivation may be the underlying reason.

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Section: Discussionmentioning

confidence: 86%

Section: Comparison Of Our Results With the Literaturementioning

confidence: 99%

A Comparison of Chronaxies for Ventricular Fibrillation Induction, Defibrillation, and Cardiac Stimulation: Unexpected Findings and Their Implications

Lawo

Deneke

Schrader

et al. 2009

Cardiovasc electrophysiol

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“…6,12 However, none of these studies have compared the difference of strength-duration curves between the 6 commercially available LV configurations, nor have reported these strength-duration curves in terms of delivered energy. We found the Tip3 RV coil configuration to have the lowest voltage and energy strength-duration curve, whereas the Ring3 Can configuration had the highest energy strengthduration curve ( Figure, A and B).…”

Section: Prior Studies Comparing LV Pacing Configurationsmentioning

confidence: 99%

“…15,16 However, most published studies of clinical data of strength-duration curve have been performed using peak voltage. 3,6,8,12,17 (3) Strength-duration curves were constructed using the Lapicque formula (rheobase voltage and chronaxie). LV thresholds were obtained at 0.4 ms and 1.5 ms (rheobase), and chronaxie pulse width was obtained using twice the rheobase voltage.…”

mentioning

confidence: 99%

Disparity in Left Ventricular Stimulation Among Different Pacing Configurations in Cardiac Resynchronization Therapy

Huízar

Kaszala

Koneru

et al. 2012

Circ: Arrhythmia and Electrophysiology

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Background-Cardiac resynchronization therapy (CRT) demands high energy utilization due to continuous biventricular pacing. Current technology allows 6 pacing configurations for a bipolar left ventricular (LV) lead. Understanding the energy requirements for each configuration will allow optimization of pacing output. Methods and Results-Pacing impedance, LV voltage threshold at 1.5 ms (rheobase) and 0.4 ms and chronaxie were obtained in 6 LV configurations in 49 consecutive patients undergoing CRT implantation or replacement. Strengthduration curves were derived using the Lapicque formula. Pacing impedances and voltage thresholds at 1.5 and 0.4 ms, calculated minimum threshold energy at chronaxie, current drain, energy thresholds at 0.4 ms, and strength-duration curves were statistically different between LV configurations (PϽ0.05). The lowest threshold energy requirements were found in Tip3right ventricular (RV) coil and Tip3 Can configuration. Energy strength-duration curves involving the ring as the cathode (Ring3 RV, Ring3 Can, and Ring3 Tip) had the highest LV thresholds. The pacing configuration with the lowest energy threshold correlated 89% of the time with the lowest voltage threshold at 0.4 ms. The probability to reach LV thresholds Ͻ1.5 V at 0.4 ms was increased from 51% with 2 LV configurations to 67% with 6 LV configurations. Conclusions-Pacing impedance, LV thresholds, minimum threshold energy at chronaxie, current drain, voltage, and energy strength-duration curves were statistically different between LV pacing configurations. LV pacing configuration with the lowest voltage threshold does not always reflects the lowest energy threshold, particularly in the presence of a low impedance configuration. The availability of 6 LV configurations increases the probability of optimizing LV pacing output. (Circ Arrhythm Electrophysiol. 2012;5:140-146.)Key Words: cardiac resynchronization therapy Ⅲ biventricular pacing Ⅲ pacing thresholds Ⅲ strength-duration curve C ardiac resynchronization therapy (CRT) has been developed as an adjunctive therapy in patients with congestive heart failure and left bundle-branch block. This therapy requires effective, safe, and permanent biventricular pacing to obtain clinical benefit and anatomic remodeling. 1 With implantation of a bipolar lead in the coronary sinus, current technology allows electronic programming of 6 different left ventricular (LV) pacing configurations or vectors. Frequently, LV pacing thresholds show a wide variation among LV pacing configurations in the same patient. To our knowledge, no prior studies have investigated the difference in LV thresholds and strength-duration curves between LV pacing configurations in the same patient. The main objective of this study was to determine and understand the difference of LV pacing thresholds and strength-duration curves among different LV pacing configurations, which in turn might provide insights to optimize LV pacing output and battery longevity. Clinical Perspective on p 146 MethodsThis prospective study inc...

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“…Strength-duration curves were theoretically studied for optimizing ventricular defibrillation thresholds for both square-wave stimulation pulses and exponential discharge pulses and were shown to be ideally hyperbolic (Irnich 2008;Koning et al 1975). Experimental studies of strength-duration relationships were conducted, e.g., in the left ventricular epicardium of patients undergoing cardiac resynchronization therapy (Dhar et al 2009;Scally et al 2007), in the right ventricular apex for transvenous defibrillation in humans and in animal models, as well as in the atria and ventricles of patients with acutely implanted pacing leads (Coates and Thwaites 2000;Gold and Shorofsky 1997;Lawo et al 2009). …”

Section: Introductionmentioning

confidence: 99%

Subthreshold Parameters of Cardiac Tissue in a Bi-Layer Computer Model of Heart Failure

Zlochiver

2010

Cardiovasc Eng

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Current density threshold and liminal area are subthreshold parameters of the cardiac tissue that indicate its susceptibility to external and internal stimulations. Extensive experimental and theoretical research has been conducted to quantify these two parameters in normal conditions for both animal and human models. Here we employed a 2D numerical model of human cardiac tissue to assess these subthreshold parameters under the pathological conditions of heart failure and fibrosis. Stimuli were applied over an area ranging from 0.04 to 1 mm² using various pulse durations. The current density threshold decreased with increasing stimulation area or pulse duration. No significant changes were found in both parameters between control conditions and heart failure in the atrial tissue, while in the ventricular tissue, heart failure resulted in significantly reduced excitability with higher stimulation current magnitudes needed for excitation and larger liminal areas. This results from the specific ionic remodeling in ventricular heart failure that affects both subthreshold active currents such as I(K₁) and connexin 43 conductance. In fibrosis, increased fibroblast to myocyte coupling coefficient had a non-linear influence on current density thresholds, with an initial increase of current magnitude followed by a relaxation phase down to the current magnitude threshold for the control condition with no fibrosis. The results show that subthreshold excitation properties of the myocardium are influenced in a complex, non-linear manner by cardiac pathologies. Such observations may contribute to our understanding of impulse capturing properties, relevant, for example, for the generation of ectopic foci-originated arrhythmias and for the efficient design of cardiac stimulating electrodes.

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Strength Duration Curve for Epicardial Left Ventricular Stimulation

Cited by 7 publications

References 4 publications

A Comparison of Chronaxies for Ventricular Fibrillation Induction, Defibrillation, and Cardiac Stimulation: Unexpected Findings and Their Implications

A Comparison of Chronaxies for Ventricular Fibrillation Induction, Defibrillation, and Cardiac Stimulation: Unexpected Findings and Their Implications

Disparity in Left Ventricular Stimulation Among Different Pacing Configurations in Cardiac Resynchronization Therapy

Subthreshold Parameters of Cardiac Tissue in a Bi-Layer Computer Model of Heart Failure

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