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.

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.

scholarly journals Postnatal neonatal myocardial adaptation is associated with loss of tolerance to tachycardia: a simultaneous invasive and noninvasive assessment

2016 ◽  
Vol 310 (5) ◽  
pp. H598-H607 ◽  
Author(s):  
Etienne Fortin-Pellerin ◽  
Nee S. Khoo ◽  
Lindsay Mills ◽  
James Y. Coe ◽  
Jesus Serrano-Lomelin ◽  
...  
Keyword(s):  
Atrial Tachycardia ◽  
Age Groups ◽  
Left Ventricular ◽  
Atrial Pacing ◽  
Apical Rotation ◽  
Filling Time ◽  
Basal Rotation ◽  
Preload Reduction ◽  
Myocardial Adaptation ◽  
The Impact

Doppler studies at rest suggest left ventricular (LV) diastolic function rapidly improves from the neonate to infant. Whether this translates to its response to hemodynamic challenges is uncertain. We sought to explore the impact of early LV maturation on its ability to tolerate atrial tachycardia. As tachycardia reduces filling time, we hypothesized that the neonatal LV would be less tolerant of atrial tachycardia. Landrace cross piglets of two age groups (1–3 days; NPs; 14–17 days, YPs; n = 7/group) were instrumented for an atrial pacing protocol (from 200 to 300 beats/min) and assessed by invasive monitoring and echocardiography. NPs maintained their LV output and blood pressure, whereas YPs did not. Although negative dP/d t in NPs at baseline was lower than that of YPs (−1,599 ± 83 vs. −2,470 ± 226 mmHg/s, respectively, P = 0.007), with increasing tachycardia negative dP/d t converged between groups and was not different. Both groups had similar preload reduction during tachycardia; however, NPs maintained shortening fraction while YPs decreased (NPs: 35.4 ± 1.4 vs. 31.8 ± 2.2%, P = 0.35; YPs: 31.4 ± 0.8 vs. 22.9 ± 0.8%, P < 0.001). Contractility measures did not differ between groups. Peak LV twist and untwisting rate also did not differ; however, NPs tended to augment LV twist through increased apical rotation and YPs through increasing basal rotation ( P = 0.009). The NPs appear more tolerant of atrial tachycardia than the YPs. They have at least similar diastolic performance, enhanced systolic performance, and different LV twist mechanics, which may contribute to improved tachycardia tolerance of NPs.

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.

P2603Impaired right ventricular force-frequency relationship in patients with heart failure is associated with diastolic dysfunction and worse functional capacity

2019 ◽  
Vol 40 (Supplement_1) ◽  
Author(s):  
A Giammarresi ◽  
M Losito ◽  
V Labate ◽  
F Bandera ◽  
M Caracciolo ◽  
...  
Keyword(s):  
Heart Failure ◽  
Heart Rate ◽  
Ejection Fraction ◽  
Right Ventricular ◽  
Left Ventricular ◽  
Peak Exercise ◽  
Force Frequency ◽  
Lv Ejection Fraction ◽  
Frequency Relationship ◽  
The Right

Abstract Background The force-frequency relationship (FFR) is an important intrinsic regulatory mechanism of cardiac contractility, related to changes in Ca2+ availability within the myocardial cell. In normal hearts this relationship is positive, so that an increase in contractile force is induced by elevation of the stimulation frequency. In heart failure (HF), the force-frequency relationship can be markedly depressed, but most studies focused their attention on left ventricular function and little is known about the right ventricle (RV). Purpose We aimed at performing a comprehensive analysis of HF phenotypes based on the right ventricular force-frequency relationship. To this purpose we stratified a large cohort of HF patients using the relationship between RV function (assessed by tricuspid annular plane systolic excursion, TAPSE) and heart rate (HR) during a symptom-limited cardiopulmonary exercise test (CPET). Material and methods We prospectively enrolled 184 HF patients, irrespective of their LV ejection fraction. We performed a stress echocardiographic evaluation using a tiltable cycle ergometer, recording standard images to assess LV systolic, diastolic, and valvular function. We divided patients in 2 groups using the slope of the linear relationship between TAPSE and HR at rest and at peak exercise, as follows: slope ≥0,01 for “positive” FFR, slope <0,01 for “flat or negative” FFR. Differences between groups were tested using unpaired t-tests for continuous variables (or Mann-Whitney U tests, when appropriate) and chi-square tests for categorical variables. Results 55 patients had a “flat or negative” FFR: they were slighty older (age 70±10 vs. 66±12; p=0,036), but the 2 groups had similar clinical characteristics such as hypertension, diabetes or COPD rate. Patients with a “flat or negative” FFR had a worse diastolic function, with higher left ventricular filling pressures (E/e' ratio 24±10 vs. 19±11 p=0,022) and left atrial volume (LAVi 55±29 ml/m2 vs. 44±20 ml/m2; p=0,009). No differences in LV ejection fraction, mitral regurgitation and pulmonary artery systolic pressure were observed between the groups. TAPSE at rest was similar between the groups (18±5 mm vs. 18±4 mm; p=0,553) but significantly different at peak exercise (16±4 mm vs. 22±5 mm; p<0,001). Average peak heart rate was similar in the 2 groups. Patients with a “flat or negative” FFR exhibited a significantly lower peak VO2 (11,6±3,0 ml/min/kg vs. 13,5±4,4 ml/min/kg; p=0,003), whereas they had a higher VE/VCO2 slope (35,1±9,6 vs. 32,3±8,2 p=0,05). RV Force-Frequency relationship Conclusion The “flat or negative” right ventricular force-frequency relationship identifies a peculiar phenotype, with a higher grade of diastolic dysfunction and an impaired exercise capacity. The inability to adapt right ventricular contractility with increasing heart rate seems not related to RV afterload (similar PASP increase) but rather to an intrinsic failure of the right heart.

Contribution of frequency-augmented inward Ca2+ current to myocardial contractility

2009 ◽  
Vol 87 (1) ◽  
pp. 69-75 ◽  
Author(s):  
Leonard D. Parilak ◽  
David G. Taylor ◽  
Yejia Song ◽  
Thomas Burkart ◽  
John C. Shryock ◽  
...  
Keyword(s):  
Heart Rate ◽  
Action Potential ◽  
Myocardial Contractility ◽  
Human Action ◽  
Left Ventricular ◽  
Monophasic Action Potential ◽  
Force Frequency ◽  
Rate Dependent ◽  
Frequency Relationship

The sarcoplasmic reticular Ca2+ pump (SERCA) is thought to be the primary determinant of heart rate-dependent increases in myocardial contractile [Ca2+]i and force (force–frequency relationship (FFR)), an important mechanism to increase cardiac output. This report demonstrates a rate-dependent role for inward Ca2+ current (ICa) in the human and rat FFR. Human action potential plateau height increased linearly with contractility when heart rate increased in vivo, as measured by monophasic action potential catheter and echocardiography. Rat rate-dependent developed force and cytosolic [Ca2+]i transients were quantified in isolated left ventricular papillary muscles, and ICa and action potential duration in cardiomyocytes. ICa and SERCA measurements better reflected [Ca2+]i and force transients than SERCA activity alone. These data support a direct and (or) indirect contribution to myocardial contractility by ICa at heart rates from approximately 1 to 3–4 Hz (60 to 180–240 bpm) in tandem with SERCA to sustain the typical ‘bell shape’ of the FFR across species.

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

Positive Inotropic and Lusitropic Effects of Triiodothyronine in Conscious Dogs with Pacing-induced Cardiomyopathy 

1997 ◽  
Vol 87 (1) ◽  
pp. 102-109 ◽  
Author(s):  
Iyad N. Jamali ◽  
Paul S. Pagel ◽  
Douglas A. Hettrick ◽  
Dermot Lowe ◽  
Judy R. Kersten ◽  
...  
Keyword(s):  
Heart Rate ◽  
Myocardial Contractility ◽  
Diastolic Pressure ◽  
Left Ventricular ◽  
Conscious Dogs ◽  
Segment Length ◽  
Lv Function ◽  
Baseline Heart Rate ◽  
Stroke Work ◽  
Lv Dysfunction

Background The effects of triiodothyronine (T3) on systemic hemodynamics, myocardial contractility (preload recruitable stroke work slope; Mw), and left ventricular (LV) isovolumic relaxation (time constant; tau) were examined before and after the development of pacing-induced cardiomyopathy in conscious dogs. Methods Dogs (n = 8) were chronically instrumented for measurement of aortic and LV pressure, dP/dtmax, subendocardial segment length, and cardiac output. Dogs received escalating doses (0.2, 2.0, and 20.0 mg/kg, intravenous) of T3 over 5 min at 1-h intervals, and peak hemodynamic effects were recorded 10 min after each dose and 24 h after the final dose. Dogs were then continuously paced at 220-240 beats/min for 21 +/- 2 days. Pacing was temporarily discontinued after the development of severe LV dysfunction, and administration of T3 was repeated. Results T3 produced immediate and sustained (24 h) increases (P &lt; 0.05) in Mw and dP/dtmax in dogs before the initiation of pacing, consistent with a positive inotropic effect. No changes in tau occurred. Rapid ventricular pacing over 3 weeks increased baseline heart rate (sinus rhythm) and LV end-diastolic pressure, decreased mean arterial and LV systolic pressures, and caused LV systolic (decreases in Mw and dP/dtmax) and diastolic (increases in tau) dysfunction. T3 caused immediate and sustained increases in Mw (63 +/- 7 during control to 82 +/- 7 mmHg after the 2 mg/kg dose) and decreases in tau (65 +/- 8 during control to 57 +/- 6 ms after the 20 mg/kg dose), indicating that this hormone enhanced myocardial contractility and shortened LV relaxation, respectively, in the presence of chronic LV dysfunction. In contrast to the findings in dogs with normal LV function, T3 did not affect heart rate and calculated indices of myocardial oxygen consumption and reduced LV end-diastolic pressure (27 +/- 3 during control to 20 +/- 2 mmHg after the 2 mg/kg dose) in cardiomyopathic dogs. Conclusions The findings indicate that T3 produces favorable alterations in hemodynamics and modest positive inotropic and lusitropic effects in conscious dogs with LV dysfunction produced by rapid LV pacing.

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.

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