Strain Rate in Children and Young Piglets Mirrors Changes in Contractility and Demonstrates a Force-Frequency Relationship

2017 ◽  
Vol 30 (8) ◽  
pp. 797-806 ◽  
Author(s):  
Silvia V. Alvarez ◽  
Etienne Fortin-Pellerin ◽  
Mohammed Alhabdan ◽  
Jesus S. Lomelin ◽  
Michal Kantoch ◽  
...  
Keyword(s):  
Strain Rate ◽  
Force Frequency ◽  
Frequency Relationship

Strain, Strain Rate, and the Force Frequency Relationship in Patients with and without Heart Failure

2012 ◽  
Vol 25 (3) ◽  
pp. 341-348 ◽  
Author(s):  
Susanna Mak ◽  
Harriette G.C. Van Spall ◽  
Rodrigo V. Wainstein ◽  
Zion Sasson
Keyword(s):  
Heart Failure ◽  
Strain Rate ◽  
Force Frequency ◽  
Frequency Relationship

Abstract 17892: Strain Rate is Affected by Heart Rate in Younger Heart: A Simultaneous Invasive and Noninvasive in vivo Piglet Model

Circulation ◽  
2015 ◽  
Vol 132 (suppl_3) ◽  
Author(s):  
Etienne Fortin-Pellerin ◽  
Lisa K Hornberger ◽  
James Y Coe ◽  
Lindsay Mills ◽  
Jesus Serrano-Lomelin ◽  
...  
Keyword(s):  
Heart Rate ◽  
Strain Rate ◽  
Atrial Tachycardia ◽  
Young Infant ◽  
Left Ventricular ◽  
Baseline Heart Rate ◽  
Force Frequency ◽  
Filling Time ◽  
Frequency Relationship ◽  
The Impact

Introduction: In adult human and pig hearts, left ventricular (LV) systolic strain rate (SR) has been shown to be independent of heart rate (HR) in atrial tachycardia. It has been hypothesized that any increase in contractility related to the force-frequency relationship is balanced by a decrease in contractility due to reduced filling time and preload at higher HRs. In this study, we explore the impact of atrial tachycardia on SR of the young infant heart using a simultaneous invasive and noninvasive piglet model to determine whether SR of the immature heart is similarly not influenced by increasing HR. Methods: Under general anesthesia (propofol, isoflurane), 1 - 15 day old piglets were instrumented intravascularly with Millar high-fidelity and pacing catheters in the left ventricle and right atrium, respectively. After stabilization, invasive hemodynamic and echocardiography parameters were acquired at baseline, and at 200, 230 and 260bpm. Basal circumferential SR was analyzed off-line by speckle tracking (frame rates 247±7 Hz). Each animal was its own control and repeated measure ANOVA was used for comparison, data is expressed as mean ± SE. Results: Fourteen piglets of mean age 8.5±1.8 days, weight 3.6±0.5kg and baseline heart rate of 152±5bpm were assessed. Baseline LV systolic SR was -1.53±0.13 1/s and dP/dt 1656±115mmHg/s. With pacing, LV SR increased significantly (p = 0.002). The increase in SR mirrored the increase in contractility assessed invasively by dP/dt (p<0.001). M-mode LV end diastolic dimension decreased from baseline to 260bpm (73±9.9% of baseline value, p < 0.001) consistent with reduced preload with tachycardia. Conclusion: Our study suggests that in the younger heart, SR is augmented by atrial tachycardia itself even in the presence of decreased preload. This is in keeping with preservation of the force frequency relationship. Given our findings, HR should be taken into account when assessing contractility using SR in young patients.

Abstract 18262: Left Ventricle Strain Rate in Children Demonstrates Heart Rate Dependence and a Force-frequency Relationship

Circulation ◽  
2015 ◽  
Vol 132 (suppl_3) ◽  
Author(s):  
Silvia Alvarez ◽  
Mohammed Alhabden ◽  
Michal Kantoch ◽  
Joseph Atallah ◽  
Timothy Colen ◽  
...  
Keyword(s):  
Heart Rate ◽  
Strain Rate ◽  
Mechanical Response ◽  
Tissue Doppler ◽  
Atrial Pacing ◽  
Force Frequency ◽  
Non Invasive ◽  
Heart Abnormalities ◽  
Frequency Relationship ◽  
Inotropic Stimulation

Introduction: In adult pigs and human studies, strain rate (SR) is a valid and reproducible marker of contractility. It is also heart rate (HR) independent, hence lacks force-frequency relationship (FFR). Isovolumic acceleration (IVA) is a proven non-invasive load-independent measure of LV contractility used in research settings. This study sought to assess SR behavior during tachycardia and inotropic stimulation in children, compared to IVA. Methods: Twenty-four patients (median age, 13.9; range 7.8 - 22.5 years) with no structural or functional heart abnormalities were evaluated after a radiofrequency ablation procedure. Echocardiogram was performed at baseline, during atrial pacing and isoprenaline infusion to achieve 130% of baseline HR. Speckle tracking global LV longitudinal SR and tissue Doppler septal IVA were measured. Relationships between HR, SR and IVA were assessed. Percent (%) change and absolute differences between SR and IVA at baseline, pacing and isoprenaline were evaluated. Data are reported as median and interquartile ranges. Results: SR and IVA showed a moderate correlation with HR at baseline (SR: r=-0.68, p=0.0002; IVA: r=0.46, p=0.01), and during pacing (SR: r=-0.56, p=0.003; IVA: r=0.58, p=0.002). Both SR and IVA increased with pacing and isoprenaline (table 1), however the greatest % change was seen during isoprenaline infusion for IVA (p < 0.006) and SR (p < 0.0001). Conclusion: SR enhances with increasing HR in children, demonstrating a relative HR dependence and a FFR. This is contrary to findings in adult studies, thus this study highlights that children show a different LV mechanical response to chronotropic effects and therefore caution should be use when extrapolating of adult findings to children.

Abstract 15596: Maturation of Hipsc-cm Electrophysiological and Contractile Function for Enhanced Sensitivity of Cardiac Safety Assays

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Heather B Hayes ◽  
Anthony M Nicolini ◽  
Colin Arrowood ◽  
Daniel Millard
Keyword(s):  
Contractile Function ◽  
Induced Pluripotent Stem Cell ◽  
Force Frequency ◽  
Cardiac Safety ◽  
Electrophysiological Response ◽  
Mechanical Conditioning ◽  
Enhanced Sensitivity ◽  
Frequency Relationship ◽  
Positive Force

Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) have significantly advanced in vitro cardiac safety and disese modeling, yet remain an immature representation of human myocytes. Electrical or mechanical conditioning of hiPSC-CMs facilitates functional maturation, as measured by a positive force-frequency relationship, but current in vitro protocols require 2-4 weeks of conditioning. Using array-based contractility and local electrical stimulation, we detected functionally mature phenotypes and compound responses in hiPSC-CMs after only 48 hours of chronic pacing. To mature cardiomyocytes, hiPSC-CMs were cultured on 24- and 96-well MEA plates with a dedicated stimulation electrodes. Later, hiPSC-CMs were electrically or optically paced at 2Hz for 48 hours. Multimodal measures quantified contractile and electrophysiological responses to varied pacing rates and compound addition. After 48 hours of pacing, hiPSC-CMs displayed shortened repolarization timing compared to before chronic pacing (baseline: 423 +/- 21 ms; matured: 316 +/- 15 ms), without significant beat period changes (baseline: 1255 +/- 40 ms; matured: 1314 +/- 84 ms). Contractile beat amplitude was measured using array-based impedance during spontaneous beating and at increasing pacing rates (1, 1.2, 1.5, 2, and 2.5 Hz). Before chronic pacing, beat amplitude decreased with increasing pacing rate; after chronic pacing, the same wells displayed increased beat amplitudes with increasing pacing rate. The matured wells also showed enhanced sensitivity to positive inotropes, such as isoproterenol, digoxin, omecamtiv mecarbil, and dobutamine. Local extracellular action potentials (LEAP) further revealed altered electrophysiological response to ranolazine, a multichannel blocker. Unpaced control wells exhibited dose-dependent APD90 prolongation in response to ranolazine, whereas matured wells showed no APD90 change. Similar results were seen with 48 hour of optogenetic pacing at 2 Hz. Overall, hiPSC-CMs chronically paced for only 48 hours exhibited more mature functional phenotypes, including a positive force-frequnecy relationship, enhanced ionotrope sensitivity, and altered compound response.

Action potential duration and force-frequency relationship in isolated rabbit, guinea pig and rat cardiac muscle

1996 ◽  
Vol 166 (2) ◽  
pp. 150-155 ◽  
Author(s):  
P. Szigligeti ◽  
C. Pankucsi ◽  
T. B�ny�sz ◽  
A. Varr� ◽  
P. P. N�n�si
Keyword(s):  
Guinea Pig ◽  
Action Potential ◽  
Cardiac Muscle ◽  
Action Potential Duration ◽  
Force Frequency ◽  
Frequency Relationship

Force-Frequency Relationship

2012 ◽  
pp. 349-349
Author(s):  
Anne Tiedemann ◽  
Catherine Sherrington ◽  
Daina L. Sturnieks ◽  
Stephen R. Lord ◽  
Mark W. Rogers ◽  
...  
Keyword(s):  
Force Frequency ◽  
Frequency Relationship
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