scholarly journals Effect of Transmural Differences in Excitation-Contraction Delay and Contraction Velocity on Left Ventricle Isovolumic Contraction: A Simulation Study

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
J. Vaverka ◽  
J. Burša ◽  
J. Šumbera ◽  
M. Pásek
Keyword(s):  
Heart Failure ◽  
Left Ventricle ◽  
Wall Stress ◽  
Element Model ◽  
Ventricular Wall ◽  
Shortening Velocity ◽  
Electromechanical Delay ◽  
Contraction Coupling ◽  
Physiological Importance ◽  
Isovolumic Contraction

Recent studies have shown that left ventricle (LV) exhibits considerable transmural differences in active mechanical properties induced by transmural differences in electrical activity, excitation-contraction coupling, and contractile properties of individual myocytes. It was shown that the time between electrical and mechanical activation of myocytes (electromechanical delay: EMD) decreases from subendocardium to subepicardium and, on the contrary, the myocyte shortening velocity (MSV) increases in the same direction. To investigate the physiological importance of this inhomogeneity, we developed a new finite element model of LV incorporating the observed transmural gradients in EMD and MSV. Comparative simulations with the model showed that when EMD or MSV or both were set constant across the LV wall, the LV contractility during isovolumic contraction (IVC) decreased significantly (dp/dtmax⁡  was reduced by 2 to 38% and IVC was prolonged by 18 to 73%). This was accompanied by an increase of transmural differences in wall stress. These results suggest that the transmural differences in EMD and MSV play an important role in physiological contractility of LV by synchronising the contraction of individual layers of ventricular wall during the systole. Reduction or enhancement of these differences may therefore impair the function of LV and contribute to heart failure.

scholarly journals Impact of Decreased Transmural Conduction Velocity on the Function of the Human Left Ventricle: A Simulation Study

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Jiří Vaverka ◽  
Jiří Moudr ◽  
Petr Lokaj ◽  
Jiří Burša ◽  
Michal Pásek
Keyword(s):  
Energy Consumption ◽  
Left Ventricle ◽  
Conduction Velocity ◽  
Heart Function ◽  
Pressure Rise ◽  
Shortening Velocity ◽  
Electromechanical Delay ◽  
Windkessel Model ◽  
Isovolumic Contraction ◽  
The Impact

This study investigates the impact of reduced transmural conduction velocity (TCV) on output parameters of the human heart. In a healthy heart, the TCV contributes to synchronization of the onset of contraction in individual layers of the left ventricle (LV). However, it is unclear whether the clinically observed decrease of TCV contributes significantly to a reduction of LV contractility. The applied three-dimensional finite element model of isovolumic contraction of the human LV incorporates transmural gradients in electromechanical delay and myocyte shortening velocity and evaluates the impact of TCV reduction on pressure rise (namely, dP/dtmax) and on isovolumic contraction duration (IVCD) in a healthy LV. The model outputs are further exploited in the lumped “Windkessel” model of the human cardiovascular system (based on electrohydrodynamic analogy of respective differential equations) to simulate the impact of changes of dP/dtmax and IVCD on chosen systemic parameters (ejection fraction, LV power, cardiac output, and blood pressure). The simulations have shown that a 50% decrease in TCV prolongs substantially the isovolumic contraction, decelerates slightly the LV pressure rise, increases the LV energy consumption, and reduces the LV power. These negative effects increase progressively with further reduction of TCV. In conclusion, these results suggest that the pumping efficacy of the human LV decreases with lower TCV due to a higher energy consumption and lower LV power. Although the changes induced by the clinically relevant reduction of TCV are not critical for a healthy heart, they may represent an important factor limiting the heart function under disease conditions.

Estimation of Left Ventricular Wall Stiffness by Analysis of Late Diastolic Pressure Components

2011 ◽  
Author(s):  
Casandra L. Niebel ◽  
Kelley C. Stewart ◽  
Takahiro Ohara ◽  
John J. Charonko ◽  
Pavlos P. Vlachos ◽  
...  
Keyword(s):  
Heart Failure ◽  
Left Ventricle ◽  
Diastolic Dysfunction ◽  
Diastolic Pressure ◽  
Left Ventricular Diastolic Dysfunction ◽  
Left Ventricular ◽  
Ventricular Wall ◽  
Ventricular Relaxation ◽  
Wall Stiffness ◽  
Ventricular Diastolic Dysfunction

Left ventricular diastolic dysfunction (LVDD) is any abnormality in the filling of the left ventricle and is conventionally evaluated by analysis of the relaxation driven phase, or early diastole. LVDD has been shown to be a precursor to heart failure and the diagnosis and treatment for diastolic failure is less understood than for systolic failure. Diastole consists of two filling waves, early and late and is primarily dependent on ventricular relaxation and wall stiffness.

scholarly journals Mechanically Unloading the Left Ventricle Before Coronary Reperfusion Reduces Left Ventricular Wall Stress and Myocardial Infarct Size

Circulation ◽  
2013 ◽  
Vol 128 (4) ◽  
pp. 328-336 ◽  
Author(s):  
Navin K. Kapur ◽  
Vikram Paruchuri ◽  
Jose Angel Urbano-Morales ◽  
Emily E. Mackey ◽  
Gerard H. Daly ◽  
...  
Keyword(s):  
Left Ventricle ◽  
Infarct Size ◽  
Myocardial Infarct ◽  
Wall Stress ◽  
Left Ventricular ◽  
Left Ventricular Wall ◽  
Myocardial Infarct Size ◽  
Ventricular Wall ◽  
Coronary Reperfusion

Abstract 17200: Plasma BNP Declines in the First Two Years After Transplant and is Elevated at the Time of Treated Rejection

Circulation ◽  
2018 ◽  
Vol 138 (Suppl_1) ◽  
Author(s):  
Tom J Valikodath ◽  
Neal Jorgensen ◽  
Erin Albers ◽  
Borah Hong ◽  
Joshua Friedland-Little ◽  
...  
Keyword(s):  
Heart Failure ◽  
Natriuretic Peptide ◽  
Ventricular Dysfunction ◽  
Multivariable Analysis ◽  
Wall Stress ◽  
Ventricular Wall ◽  
The Relationship ◽  
Pediatric Recipients ◽  
Over Time

Introduction: Plasma B-type natriuretic peptide (BNP) is a biomarker used to diagnose and monitor ventricular dysfunction and heart failure. However, the response of the allograft to produce BNP from ventricular wall stress and inflammation may be different, particularly in an understudied population such as pediatric recipients. Hypothesis: BNP levels decrease over time after transplant as the allograft recovers; but BNP will be higher during rejection. Methods: Enrolled all heart recipients from January 2007 to December 2016. Rejection surveillance included serial echocardiography, annual biopsy, and BNP q 1-3 months. Rejection is defined as requiring augmentation of immunosuppression from biopsy grade ≥ 2R or ≥ pAMR2 or from clinical diagnosis. Results: Among 114 patients studied, 60% were male with age at transplant 5.8 ± SD 6.5 yrs. Follow-up was 3.7 ± 2.7 yrs and 37 patients (32%) experienced 75 episodes of rejection. A total of 8358 BNP samples were obtained. BNP decreased linearly after transplant leveling off after 2 years (Fig 1). BNP was 671 ± 1115 (n=75) at rejection vs. 187 ± 423 pg/mL (n=501) without rejection confirmed by biopsy. By multivariable analysis, Ln BNP was associated with rejection (RR 1.56; 95% CI 1.35-1.80). Figure 2 shows the relationship between change in BNP and risk of rejection. Multivariable longitudinal Cox proportional model incorporating BNPs leading to 1 st rejection showed Ln BNP to be associated with rejection (HR 2.22; 95% CI 1.53-3.23, p<0.001). Conclusion: BNP continues to decrease in the 1 st 2 years after transplant. At rejection, BNP is elevated, and this test can be further developed to screen for rejection.

Trabecular cutting: a novel surgical therapy to increase diastolic compliance

2019 ◽  
Vol 127 (2) ◽  
pp. 457-463
Author(s):  
Meagan Oglesby ◽  
Danny Escobedo ◽  
Gladys Patricia Escobar ◽  
Fatemeh Fatemifar ◽  
Edward Y. Sako ◽  
...  
Keyword(s):  
Heart Failure ◽  
Left Ventricle ◽  
Diastolic Pressure ◽  
Ex Vivo ◽  
Systolic Function ◽  
Wall Stress ◽  
Rabbit Heart ◽  
Left Ventricular ◽  
Before And After ◽  
Diastolic Compliance

Heart failure with preserved ejection fraction (HFpEF) is a common cause of hospital admission in patients over 65 yr old and has high mortality. HFpEF is characterized by left ventricular (LV) hypertrophy that reduces compliance. Current HFpEF therapies control symptoms, but no existing medications or therapies can sustainably increase LV compliance. LV trabeculae develop hypertrophy and fibrosis that contribute to reduced LV compliance. This study expands our previous results in ex vivo human hearts to show that severing LV trabeculae increases diastolic compliance in an ex vivo working rabbit heart model. Trabecular cutting was performed in ex vivo rabbit hearts set up in a working heart perfusion system perfused with oxygenated Krebs-Henseleit buffer. A hook was inserted in the LV to cut trabeculae. End-systolic and end-diastolic pressure-volume relationships during transient preload reduction were recorded using an admittance catheter in the following three groups: control (no cutting; n = 9), mild cutting (15 cuts; n = 5), and aggressive cutting (30 cuts; n = 5). In a second experiment, each heart served as its own control. Hemodynamic data were recorded before and after trabecular cutting ( n = 10) or sham cutting ( n = 5) within the same heart. In the first experiments, trabecular cutting did not affect systolic function ( P > 0.05) but significantly increased overall diastolic compliance ( P = 0.009). Greater compliance was seen as trabecular cutting increased ( P = 0.002, r2 = 0.435). In the second experiment, significant increases in systolic function ( P = 0.048) and diastolic compliance ( P = 0.002) were seen after trabecular cutting compared with baseline. In conclusion, trabecular cutting significantly increases diastolic compliance without reducing systolic function. NEW & NOTEWORTHY We postulate that, in mammalian hearts, free-running trabeculae carneae exist to provide tensile support to the left ventricle and minimize diastolic wall stress. Because of hypertrophy and fibrosis of trabeculae in patients with left ventricular hypertrophy, this supportive role can become pathologic, worsening diastolic compliance. We demonstrate a novel operation involving cutting trabeculae as a method to acutely increase diastolic compliance in patients presenting with heart failure and diastolic dysfunction to improve their left ventricle compliance.

Assessment and relevance of ventricular wall stress in heart failure

2008 ◽  
Vol 29 (18) ◽  
pp. 2316-2316 ◽  
Author(s):  
P. Alter ◽  
H. Rupp ◽  
B. Maisch
Keyword(s):  
Heart Failure ◽  
Wall Stress ◽  
Ventricular Wall

scholarly journals ANALYSIS OF CHANGES IN THE SERUM LEVEL NT-proBNP AFTER ACE INHIBITORS THERAPY IN PATIENTS WITH HEART FAILURE

2017 ◽  
Vol 52 (3) ◽  
pp. 193
Author(s):  
Halla Hisan Hartoto ◽  
Bambang Subakti Zulkarnain ◽  
Muhammad Aminuddin
Keyword(s):  
Heart Failure ◽  
Left Ventricle ◽  
Ace Inhibitors ◽  
Ace Inhibitor ◽  
Nyha Class ◽  
Wall Stress ◽  
Response To Therapy ◽  
Inhibitor Therapy ◽  
Elevated Concentration ◽  
Patients With Heart Failure

BNP secreted by left ventricle as response to wall stress in patient with heart failure. Elevated concentration of NT-pro-BNP correlate with severity of heart failure across all stages of the condition and left ventricle ejection fraction in patient. Several clinical trials have demonstrated that neurohormonal modulation on the RAAS decreases NT-proBNP level and results in favorable outcomes. One of the drug used for blocked RAAS system is ACE inhibitor, decrease of NT-proBNP level show response to therapy include therapy with ACE inhibitors. To analize changes in the levels serum NT-proBNP levels after ace inhibitor therapy in patients with heart failure and monitoring creatinine serum. This study was a observational, prospective, non-randomized trial involving patient age 21-75 years, with NYHA class II-III HF, using ACE inhibitor therapy plus other therapy maximum 3 months before study without ARB or beta blocker. We compared serum NT-pro-BNP and creatinin serum parameters before and after two months treatment with ACE inhibitor. This study conducted in cardiovascular ambulatory patient dr. Soetomo hospital Surabaya. Between August-November 2015, 13 patient (38-63 years, 6 woman, 7 men) include in this study. The mean baseline level of NT-proBNP is 2166.92±1236.73 pg/ml, and creatinin serum 1.023±0.601 mg/dL. The NT-pro-BNP were significantly decreased after two months of treatment with ACE inhibitors 1508.23±651 pg/mL (p=0.025), there were no significant differences creatinin serum between two groups 0.951±0.0365 mg/dL (p=0.111). The results demonstrated the benefits of ACE inhibitor on the neurohormonal profile in patients with HF. If necessary we could measure NT-proBNP level to support prognosis data and monitoring effectivity therapy especially ACE inhibitor which had antiremodelling effect towards patients with HF.

scholarly journals Remodeling of left circumflex coronary arterial tree in pacing-induced heart failure

2015 ◽  
Vol 119 (4) ◽  
pp. 404-411 ◽  
Author(s):  
Yunlong Huo ◽  
Ghassan S. Kassab
Keyword(s):  
Heart Failure ◽  
Left Ventricle ◽  
Flow Resistance ◽  
Coronary Circulation ◽  
Supply And Demand ◽  
Wall Stress ◽  
Arterial Tree ◽  
Computer Reconstruction ◽  
Vascular Flow ◽  
And Control

Congestive heart failure (CHF) is a very serious heart disease that manifests an imbalance between left ventricle supply and demand. Although the mechanical demand of the failing heart has been well characterized, the systematic remodeling of the entire coronary arterial tree that constitutes the supply of the myocardium is lacking. We hypothesize that the well-known increase in ventricle wall stress during CHF causes coronary vascular rarefaction to increase the vascular flow resistance, which in turn compromises the perfusion of the heart. Morphometric (diameters, length, and numbers) data of the swine left circumflex (LCx) arterial tree were measured in both CHF ( n = 6) and control ( n = 6) groups, from which a computer reconstruction of the entire LCx tree was implemented down to the capillary level to enable a hemodynamic analysis of coronary circulation. The vascular flow resistance was increased by ∼75% due to a significant decrease of vessel numbers (∼45%) and diameters in the first capillary segments (∼10%) of the LCx arterial tree after 3-4 wk of pacing. The structural remodeling significantly changed the wall shear stress in vessel segments of the entire LCx arterial tree of CHF animals. This study enhances our knowledge of coronary arterial tree remodeling in heart failure, which provides a deeper understanding of the deterioration of supply-demand relation in left ventricle.

Sign in / Sign up

Export Citation Format

Share Document