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 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.

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

Invasive hemodynamics and force-frequency relationships in open- versus closed-chest mice

1997 ◽  
Vol 273 (5) ◽  
pp. H2528-H2533 ◽  
Author(s):  
Brian D. Hoit ◽  
Nancy Ball ◽  
Richard A. Walsh
Keyword(s):  
Heart Rate ◽  
Systolic Pressure ◽  
Left Ventricular ◽  
Force Frequency ◽  
Closed Chest ◽  
Open Chest ◽  
Systolic And Diastolic Function ◽  
Frequency Relationship ◽  
Maximal Rise ◽  
Open Versus

We compared hemodynamics, ventricular function, and force-frequency relationships in six open-chest and six closed-chest anesthetized mice (FVB/N strain). Left ventricular (LV) pressure was measured with a 1.8- or 1.4-Fr Millar catheter placed via the right carotid artery and the LV apex in the closed- and open-chest state, respectively. Pacing was performed with electrodes placed either directly on atrial appendages (open chest) or with a 1-Fr bipolar catheter via the jugular vein (closed chest). Closed-chest animals had greater spontaneous heart rate (267 ± 106 vs. 147 ± 27 beats/min), LV systolic (81 ± 14 vs. 48 ± 9 mmHg) and diastolic pressures (11.2 ± 4.8 vs. 5.6 ± 2.4 mmHg), and maximal rise (+dP/d t max: 6,208 ± 2,519 vs. 3,682 ± 671 mmHg/s) and fall in pressure development (−dP/d t max: −6,094 ± 2,386 vs. −3,001 ± 399 mmHg/s). LV systolic pressure (98 ± 18 vs. 52 ± 11 mmHg), +dP/d t max (9,240 ± 2,459 vs. 5,777 ± 2,473 mmHg/s), and −dP/d t max(−8,375 ± 2,551 vs. −3,753 ± 1,170 mmHg/s) were significantly higher when animals were matched at a heart rate of 420 beats/min in closed-chest vs. open-chest animals. Biphasic force-frequency relationships were seen in all animals, but the critical heart rate was greater in the closed- than open-chest animals (432 ± 42 vs. 318 ± 42 beats/min). We conclude that 1) there are significant differences between invasive indexes of systolic and diastolic function between the closed- and open-chest preparations, 2) there is a biphasic force-frequency relationship in the anesthetized mouse, and 3) dP/d t max can be used to assess the cardiovascular phenotype.

Modulation of force-frequency relation by phospholamban in genetically engineered mice

1999 ◽  
Vol 276 (6) ◽  
pp. H2245-H2250 ◽  
Author(s):  
Vivek J. Kadambi ◽  
Nancy Ball ◽  
Evangelia G. Kranias ◽  
Richard A. Walsh ◽  
Brian D. Hoit
Keyword(s):  
Heart Rate ◽  
Myocardial Contractility ◽  
Left Ventricular ◽  
Atrial Pacing ◽  
Force Frequency ◽  
Cardiac Sarcoplasmic Reticulum ◽  
Peak Rate ◽  
Genetically Engineered Mice ◽  
Frequency Relation

Phospholamban levels regulate cardiac sarcoplasmic reticulum Ca2+ pump activity and myocardial contractility. To determine whether and to what extent phospholamban modulates the force-frequency relation and ventricular relaxation in vivo, we studied transgenic mice overexpressing phospholamban (PLBOE), gene-targeted mice without phospholamban (PLBKO), and isogenic wild-type controls. Contractility was assessed by the peak rate of left ventricular (LV) isovolumic contraction (+dP/d t max), and diastolic function was assessed by both the peak rate (−dP/d t max) and the time constant (τ) of isovolumic LV relaxation, using a high-fidelity LV catheter. Incremental atrial pacing was used to generate heart rate vs. −dP/d t max(force-frequency) relations. Biphasic force-frequency relations were produced in all animals, and the critical heart rate (HRcrit) was taken as the heart rate at which dP/d t max was maximal. The average LV +dP/d t maxincreased in both PLBKO and PLBOE compared with their isogenic controls (both P < 0.05). The HRcrit for LV +dP/d t max was significantly higher in PLBKO (427 ± 20 beats/min) compared with controls (360 ± 18 beats/min), whereas the HRcrit in PLBOE (340 ± 30 beats/min) was significantly lower compared with that in isogenic controls (440 ± 25 beats/min). The intrinsic heart rates were significantly lower, and the HRcrit and the ±dP/d t max at HRcrit were significantly greater in FVB/N than in SvJ control mice. We conclude that 1) the level of phospholamban is a critical negative determinant of the force-frequency relation and myocardial contractility in vivo, and 2) contractile parameters may differ significantly between strains of normal mice.

Myocardial function defined by strain rate and strain during alterations in inotropic states and heart rate

2002 ◽  
Vol 283 (2) ◽  
pp. H792-H799 ◽  
Author(s):  
Frank Weidemann ◽  
Fadi Jamal ◽  
George R. Sutherland ◽  
Piet Claus ◽  
Miroslaw Kowalski ◽  
...  
Keyword(s):  
Heart Rate ◽  
Strain Rate ◽  
Contractile Function ◽  
Wall Stress ◽  
Atrial Pacing ◽  
Systolic Strain ◽  
Regional Deformation ◽  
Deformation Parameters ◽  
Systolic Wall Stress ◽  
Regional Contractile Function

For porcine myocardium, ultrasonic regional deformation parameters, systolic strain (εsys) and peak systolic strain rate (SRsys), were compared with stroke volume (SV) and contractility [contractility index (CI)] measured as the ratio of end-systolic strain to end-systolic wall stress. Heart rate (HR) and contractility were varied by atrial pacing (AP = 120–180 beats/min, n = 7), incremental dobutamine infusion (DI = 2.5–20 μg · kg−1 · min−1, n = 7), or continuous esmolol infusion (0.5 mg · kg−1 · min−1) + subsequent pacing (120–180 beats/min) (EI group, n= 6). Baseline SRsys and εsys averaged 5.0 ± 0.4 s−1 and 60 ± 4%. SRsysand CI increased linearly with DI (20 μg · kg−1 · min−1; SRsys = 9.9 ± 0.7 s−1, P < 0.0001) and decreased with EI (SRsys = 3.4 ± 0.1 s−1, P < 0.01). During pacing, SRsys and CI remained unchanged in the AP and EI groups. During DI, εsys and SV initially increased (5 μg · kg−1 · min−1; εsys = 77 ± 6%, P < 0.01) and then progressively returned to baseline. During EI, SV and εsys decreased (εsys = 38 ± 2%, P < 0.001). Pacing also decreased SV and εsys in the AP (180 beats/min; εsys = 36 ± 2%, P < 0.001) and EI groups (180 beats/min; εsys = 25 ± 3%, P< 0.001). Thus, for normal myocardium, SRsys reflects regional contractile function (being relatively independent of HR), whereas εsys reflects changes in SV.

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