scholarly journals Simulation of Left Ventricular Dynamics Using a Low-Order Mathematical Model

2017 ◽  
Vol 8 (4) ◽  
pp. 480-494 ◽  
Author(s):  
Michael J. Moulton ◽  
Brian D. Hong ◽  
Timothy W. Secomb
Keyword(s):  
Mathematical Model ◽  
Left Ventricular ◽  
Ventricular Dynamics ◽  
Low Order

Ultrasonic Visualization of Left Ventricular Dynamics

1970 ◽  
Vol 17 (3) ◽  
pp. 143-153 ◽  
Author(s):  
R.C. Eggleton ◽  
C. Townsend ◽  
J. Herrick ◽  
G. Templeton ◽  
J.H. Mitchell
Keyword(s):  
Left Ventricular ◽  
Ventricular Dynamics

Impact of ejection on magnitude and time course of ventricular pressure-generating capacity

1993 ◽  
Vol 265 (3) ◽  
pp. H899-H909 ◽  
Author(s):  
D. Burkhoff ◽  
P. P. De Tombe ◽  
W. C. Hunter
Keyword(s):  
Time Course ◽  
Cardiac Cycle ◽  
Left Ventricular Pressure ◽  
Left Ventricular ◽  
Ventricular Pressure ◽  
Time Varying ◽  
Generating Capacity ◽  
Ejection Phase ◽  
Time Point ◽  
Ventricular Dynamics

This study focuses on elucidating how ventricular afterloading conditions affect the time course of change of left ventricular pressure (LVP) throughout the cardiac cycle, with particular emphasis on revealing specific limitations in the time-varying elastance model of ventricular dynamics. Studies were performed in eight isolated canine hearts ejecting into a simulated windkessel afterload. LVP waves measured (LVPm) during ejection were compared with those predicted (LVPpred) according to the elastance theory. LVPm exceeded LVPpred from a time point shortly after the onset of ejection to the end of the beat. The instantaneous difference between LVPm and LVPpred increased steadily as ejection proceeded and reached between 45 and 65 mmHg near end ejection. This was in large part due to an average 35-ms prolongation of the time to end systole (tes) in ejecting compared with isovolumic beats. The time constant of relaxation was decreased on ejecting beats so that, despite the marked prolongation of tes, the overall duration of ejecting contractions was not greater than that of isovolumic beats. The results demonstrate a marked ejection-mediated enhancement and prolongation of ventricular pressure-generating capacity during the ejection phase of the cardiac cycle with concomitant acceleration of relaxation. None of these factors are accounted for by the time-varying elastance theory.

scholarly journals Diagnostic value of electrocardiographic markers of left bundle branch block in predicting left ventricular reverse remodeling in patients receiving cardiac resynchronization therapy

2021 ◽  
Vol 26 (9) ◽  
pp. 4500
Author(s):  
L. M. Malishevsky ◽  
V. A. Kuznetsov ◽  
V. V. Todosiychuk ◽  
N. E. Shirokov ◽  
D. S. Lebedev
Keyword(s):  
Mathematical Model ◽  
Cardiac Resynchronization Therapy ◽  
Predictive Value ◽  
Diagnostic Value ◽  
Left Ventricular ◽  
Cardiac Resynchronization ◽  
Reverse Remodeling ◽  
Resynchronization Therapy ◽  
Bundle Branch Block ◽  
T Wave

Aim. To analyze the prognostic value of 18 electrocardiographic (ECG) markers of left bundle branch block (LBBB) in predicting left ventricular (LV) reverse remodeling in patients receiving cardiac resynchronization therapy (CRT).Material and methods. The study included 98 patients. Depending on the presence of reverse remodeling during CRT, defined as a decrease in LV endsystolic volume ≥15%, the patients were divided into two groups: non-responders (n=33) and responders (n=65). We selected and analyzed 18 ECG markers included in 9 LBBB criteria.Results. Among the ECG markers significantly associated with reverse remodeling during CRT, the absence of q wave in leads V5-V6 demonstrated the highest sensitivity (92,31%), a negative predictive value (70,59%) and overall accuracy (73,47%). Normal internal deviation interval of the R wave in leads V1-V3 was also associated with the best sensitivity (92.31%), while QS with a positive T in lead aVR — the best specificity (69,7%). Discordant T wave demonstrated the highest positive predictive value (80,33%). Multivariate analysis revealed following ECG signs independently associated with reverse remodeling during CRT: QRS complex duration (odds ratio (OR)=1,022; 95% confidence interval (CI): 1,001-1,043; p=0,040); absence of q wave in leads V5-V6 (OR=4,076; 95% CI: 1,071-15,51; p=0,039); discordant T wave (OR=4,565; 95% CI: 1,708-12,202; p=0,002). These ECG findings were combined into a mathematical model that demonstrated high predictive power (AUC=0,81 [0,722-0,898], p<0,001). Once the cut-off point was determined, a binary variable was obtained that showed higher sensitivity, negative predictive value, and overall accuracy when compared with the actual LBBB criteria. The 5-year survival rate among patients with a model value above the cut-off point was 84,4%, while in patients with a value below the cut-off point — 50% (Log-rank test, p=0,001). To improve usability of the model, a mobile application was developed.Conclusion. For the first time, the diagnostic value of ECG markers of LBBB were analyzed and a mathematical model with ECG signs was proposed to predict reverse remodeling in patients receiving CRT.

Mechanics of left ventricular relaxation, early diastolic lengthening, and suction investigated in a mathematical model

2011 ◽  
Vol 300 (5) ◽  
pp. H1678-H1687 ◽  
Author(s):  
Espen W. Remme ◽  
Anders Opdahl ◽  
Otto A. Smiseth
Keyword(s):  
Mathematical Model ◽  
Relaxation Rate ◽  
Left Ventricular ◽  
Force Balance ◽  
Passive Stiffness ◽  
Ventricular Relaxation ◽  
Active Fiber ◽  
Restoring Forces ◽  
Definition Of ◽  
Early Filling

We investigated the determinants of ventricular early diastolic lengthening and mechanics of suction using a mathematical model of the left ventricle (LV). The model was based on a force balance between the force represented by LV pressure (LVP) and active and passive myocardial forces. The predicted lengthening velocity ( e′) from the model agreed well with measurements from 10 dogs during 5 different interventions ( R = 0.69, P < 0.001). The model showed that e′ was increased when relaxation rate and systolic shortening increased, when passive stiffness was decreased, and when the rate of fall of LVP during early filling was decreased relative to the rate of fall of active stress. We first defined suction as the work the myocardium performed to pull blood into the ventricle. This occurred when contractile active forces decayed below and became weaker than restoring forces, producing a negative LVP. An alternative definition of suction is filling during falling pressure, commonly believed to be caused by release of restoring forces. However, the model showed that this phenomenon also occurred when there had been no systolic compression below unstressed length and therefore in the absence of restoring forces. In conclusion, relaxation rate, LVP, systolic shortening, and passive stiffness were all independent determinants of e′. The model generated a suction effect seen as lengthening occurring during falling pressure. However, this was not equivalent with the myocardium performing pulling work on the blood, which was performed only when restoring forces were higher than remaining active fiber force, corresponding to a negative transmural pressure.

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