Contractile function in canine right ventricle

1980 ◽  
Vol 239 (6) ◽  
pp. H794-H804 ◽  
Author(s):  
G. D. Meier ◽  
A. A. Bove ◽  
W. P. Santamore ◽  
P. R. Lynch
Keyword(s):  
High Speed ◽  
Animal Studies ◽  
Contractile Function ◽  
Minor Component ◽  
Local Deformation ◽  
Wall Thickening ◽  
Free Wall ◽  
Ventricular Performance ◽  
Length Changes ◽  
Principal Directions

Regional right ventricular (RV) motion was examined in six acutely instrumented dogs by implanting radiopaque markers in three regions of the free wall: the apex, the midventricle, and the outflow tract. These markers were filmed at the paced heart rate of 180 beats/min with a high-speed biplane X-ray system, and their motion was analyzed with a digital computer. Local deformation was separated into percent length changes in the two mutually perpendicular principal directions. The major component exhibited shortening along a path from apex to conus. (apex - 13.6%, midventricle -13.1%, conus -8.7%); the minor component exhibited small amounts of lengthening and some shortening (apex +4.7%, midventricle +1.8%, conus -0.5%). From these two measurements we calculated the peak RV free wall thickening (apex 13.6%, midventricle 14.1%, conus 10.9%). The experimental technique developed for this study was found to be suitable for the repeated analysis of intact ventricular performance in chronic animal studies. The results reveal that in systole the RV free wall undergoes a sequential contraction, which begins at the apex and ends in the conus.

Assessment of Myocardial Viability in Persistent Defects on Thallium-201 SPECT after Reinjection Using Gradient-Echo MRI

1996 ◽  
Vol 35 (05) ◽  
pp. 146-152 ◽  
Author(s):  
A. Kögler ◽  
H.-A. Schmitt ◽  
D. Emrich ◽  
H. Kreuzer ◽  
D. L. Munz ◽  
...  
Keyword(s):  
Wall Thickness ◽  
Myocardial Viability ◽  
Cardiac Cycle ◽  
Single Photon ◽  
Contractile Function ◽  
Left Ventricular ◽  
Wall Thickening ◽  
Gradient Echo ◽  
Systolic Wall Thickening

SummaryThis prospective study assessed myocardial viability in 30 patients with coronary heart disease and persistent defects despite reinjection on TI-201 single-photon computed tomography (SPECT). In each patient, three observers graded TI-201 uptake in 7 left ventricular wall segments. Gradient-echo magnetic resonance imaging in the region of the persistent defect generated 12 to 16 short axis views representing a cardiac cycle. A total of 120 segments were analyzed. Mean end-diastolic wall thickness and systolic wall thickening (± SD) was 11.5 ± 2.7 mm and 5.8 ± 3.9 mm in 48 segments with normal TI-201 uptake, 10.1 ± 3.4 mm and 3.7 ± 3.1 mm in 31 with reversible lesions, 11.3 ± 2.8 mm and 3.3 ± 1.9 mm in 10 with mild persistent defects, 9.2 ± 2.9 mm and 3.2 ±2.2 mm in 15 with moderate persistent defects, 5.8 ± 1.7 mm and 1.3 ± 1.4 mm in 16 with severe persistent defects, respectively. Significant differences in mean end-diastolic wall thickness (p <0.0005) and systolic wall thickening (p <0.005) were found only between segments with severe persistent defects and all other groups, but not among the other groups. On follow-up in 11 patients after revascularization, 6 segments with mild-to-moderate persistent defects showed improvement in mean systolic wall thickening that was not seen in 6 other segments with severe persistent defects. These data indicate that most myocardial segments with mild and moderate persistent TI-201 defects after reinjection still contain viable tissue. Segments with severe persistent defects, however, represent predominantly nonviable myocardium without contractile function.

Stability of Milling Operations With Asymmetric Cutter Dynamics in Rotating Coordinates

2016 ◽  
Vol 138 (8) ◽  
Author(s):  
Alptunc Comak ◽  
Orkun Ozsahin ◽  
Yusuf Altintas
Keyword(s):  
Time Domain ◽  
Machine Tools ◽  
High Speed ◽  
End Mill ◽  
Spindle Shaft ◽  
Milling Operations ◽  
Stability Model ◽  
Principal Directions ◽  
The Stability ◽  
Rotating Coordinates

High-speed machine tools have parts with both stationary and rotating dynamics. While spindle housing, column, and table have stationary dynamics, rotating parts may have both symmetric (i.e., spindle shaft and tool holder) and asymmetric dynamics (i.e., two-fluted end mill) due to uneven geometry in two principal directions. This paper presents a stability model of dynamic milling operations with combined stationary and rotating dynamics. The stationary modes are superposed to two orthogonal directions in rotating frame by considering the time- and speed-dependent, periodic dynamic milling system. The stability of the system is solved in both frequency and semidiscrete time domain. It is shown that the stability pockets differ significantly when the rotating dynamics of the asymmetric tools are considered. The proposed stability model has been experimentally validated in high-speed milling of an aluminum alloy with a two-fluted, asymmetric helical end mill.

scholarly journals High-resolution cardiovascular function confirms functional orthology of myocardial contractility pathways in zebrafish

2010 ◽  
Vol 42 (2) ◽  
pp. 300-309 ◽  
Author(s):  
Jordan T. Shin ◽  
Eugene V. Pomerantsev ◽  
John D. Mably ◽  
Calum A. MacRae
Keyword(s):  
High Speed ◽  
Dynamic Range ◽  
Model Organism ◽  
Cardiovascular Physiology ◽  
Zebrafish Embryos ◽  
Cardiovascular Development ◽  
Zebrafish Model ◽  
Ventricular Performance ◽  
Pharmacological Agents

Phenotype-driven screens in larval zebrafish have transformed our understanding of the molecular basis of cardiovascular development. Screens to define the genetic determinants of physiological phenotypes have been slow to materialize as a result of the limited number of validated in vivo assays with relevant dynamic range. To enable rigorous assessment of cardiovascular physiology in living zebrafish embryos, we developed a suite of software tools for the analysis of high-speed video microscopic images and validated these, using established cardiomyopathy models in zebrafish as well as modulation of the nitric oxide (NO) pathway. Quantitative analysis in wild-type fish exposed to NO or in a zebrafish model of dilated cardiomyopathy demonstrated that these tools detect significant differences in ventricular chamber size, ventricular performance, and aortic flow velocity in zebrafish embryos across a large dynamic range. These methods also were able to establish the effects of the classic pharmacological agents isoproterenol, ouabain, and verapamil on cardiovascular physiology in zebrafish embryos. Sequence conservation between zebrafish and mammals of key amino acids in the pharmacological targets of these agents correlated with the functional orthology of the physiological response. These data provide evidence that the quantitative evaluation of subtle physiological differences in zebrafish can be accomplished at a resolution and with a dynamic range comparable to those achieved in mammals and provides a mechanism for genetic and small-molecule dissection of functional pathways in this model organism.

Contractile function in chronic gradually developing subcoronary aortic stenosis

1981 ◽  
Vol 240 (1) ◽  
pp. H80-H84
Author(s):  
B. A. Carabello ◽  
R. Mee ◽  
J. J. Collins ◽  
R. A. Kloner ◽  
D. Levin ◽  
...  
Keyword(s):  
Aortic Stenosis ◽  
Cardiac Hypertrophy ◽  
Cardiac Muscle ◽  
Animal Studies ◽  
Contractile Function ◽  
Pressure Overload ◽  
Left Ventricular ◽  
Stroke Work ◽  
Group A ◽  
Group B

Whether hypertrophied cardiac muscle functions normally or abnormally is a point of controversy in the literature. Most animal studies showing depressed performance of hypertrophied cardiac muscle have used experimental methods in which hypertrophy was produced by acutely imposing a pressure overload on the left or right ventricle, which may cause myocardial injury. To assess the possibility that chronic, slowly developing hypertrophy is associated with normal myocardial function, we developed an experimental model in which increased afterload is imposed gradually on the left ventricle in the dog. A snug band was placed around the aorta beneath the left coronary artery in puppies without producing a stenosis. As the puppies grew, relative aortic stenosis developed as increased cardiac output flowed across that fixed outflow area. One group (group A) of six puppies was banded early, whereas a second group (group B, five puppies) was banded late and served as controls. Left ventricular weight (g) to body weight (kg) ratio remained normal in group B animals (3.9 +/- 0.14), whereas this ratio was increased to 5.3 +/- 0.24 (P < 0.001) in group A animals indicating development of moderate cardiac hypertrophy. Ejection fraction, dP/dt, Vcf, and stroke work per gram of myocardium were virtually identical in both groups. We conclude that moderate, gradually developing cardiac hypertrophy as produced by this model is associated with normal myocardial contractile performance.

Placental growth factor increases regional myocardial blood flow and contractile function in chronic myocardial ischemia

2013 ◽  
Vol 304 (6) ◽  
pp. H885-H894 ◽  
Author(s):  
Xiaoshun Liu ◽  
Piet Claus ◽  
Ming Wu ◽  
Geert Reyns ◽  
Peter Verhamme ◽  
...  
Keyword(s):  
Blood Flow ◽  
Growth Factor ◽  
Myocardial Perfusion ◽  
Contractile Function ◽  
Placental Growth Factor ◽  
Regional Myocardial Blood Flow ◽  
Wall Thickening ◽  
Systolic Wall Thickening ◽  
Regional Myocardial Blood ◽  
Chronic Myocardial Ischemia

Placental growth factor (PlGF) has a distinct biological phenotype with a predominant proangiogenic role in disease without affecting quiescent vessels in healthy organs. We tested whether systemic administration of recombinant human (rh)PlGF improves regional myocardial blood flow (MBF) and systolic function recovery in a porcine chronic myocardial ischemia model. We implanted a flow-limiting stent in the proximal left anterior descending coronary artery and measured systemic hemodynamics, regional myocardial function using MRI, and blood flow using colored microspheres 4 wk later. Animals were then randomized in a blinded way to receive an infusion of rhPlGF (15 μg·kg−1·day−1, n = 9) or PBS (control; n = 10) for 2 wk. At 8 wk, myocardial perfusion and function were reassessed. Infusion of rhPlGF transiently increased PlGF serum levels >30-fold (1,153 ± 180 vs. 33 ± 18 pg/ml at baseline, P < 0.001) without affecting systemic hemodynamics. From 4 to 8 wk, rhPlGF increased regional MBF from 0.46 ± 0.11 to 0.85 ± 0.16 ml·min−1·g−1, with a concomitant increase in systolic wall thickening from 11 ± 3% to 26 ± 5% in the ischemic area. In control animals, no significant changes from 4 to 8 wk were observed (MBF: 0.45 ± 0.07 to 0.49 ± 0.08 ml·min−1·g−1 and systolic wall thickening: 14 ± 4% to 18 ± 1%). rhPlGF-induced functional improvement was accompanied by increased myocardial neovascularization, enhanced glycogen utilization, and reduced oxidative stress and cardiomyocyte apoptosis in the ischemic zone. In conclusion, systemic rhPlGF infusion significantly enhances regional blood flow and contractile function of the chronic ischemic myocardium without adverse effects. PlGF protein infusion may represent an attractive therapeutic strategy to increase myocardial perfusion and energetics in chronic ischemic cardiomyopathy.

Coronary hyperperfusion augments myocardial oxygen consumption

1996 ◽  
Vol 271 (4) ◽  
pp. H1384-H1393 ◽  
Author(s):  
Y. Ishibashi ◽  
J. Zhang ◽  
D. J. Duncker ◽  
C. Klassen ◽  
T. Pavek ◽  
...  
Keyword(s):  
Blood Flow ◽  
Oxygen Consumption ◽  
Coronary Blood Flow ◽  
Myocardial Oxygen Consumption ◽  
Contractile Function ◽  
Left Ventricular ◽  
Wall Thickening ◽  
Systolic Thickening ◽  
Subepicardial Layer ◽  
Systolic Wall Thickening

This study was performed to test the hypothesis that increases in myocardial oxygen consumption (MVo2) and myocardial contractile function during exercise are flow limited. Studies were performed in 15 chronically instrumented normal dogs. MVo2 and regional percent systolic wall thickening were measured during control conditions and during maximal vasodilation produced by infusion of adenosine (20-75 micrograms.kg-1.min-1) or adenosine combined with nitroglycerin (0.4 micrograms.kg-1.min-1; TNG) into the left anterior descending coronary artery during a three-stage graded treadmill exercise protocol. Adenosine and adenosine plus TNG significantly increased coronary blood flow by 298 +/- 26 and 306 +/- 24%, respectively, at rest and by 134 +/- 7 and 145 +/- 9%, respectively, during the heaviest level of exercise (each P < 0.01). Adenosine and adenosine plus TNG increased MVo2 at rest, but this was associated with a parallel increase in heart rate, so that MVo2 per beat was not significantly changed. Systolic wall thickening was also not changed by hyperperfusion during resting conditions. However, MVo2 per beat was increased by 12 +/- 4% with adenosine and by 13 +/- 5% with adenosine plus TNG during moderate exercise and by 23 +/- 5% with adenosine and by 27 +/- 4% with adenosine plus TNG during the heaviest level of exercise (each P < 0.05). Systolic thickening of the full left ventricular wall did not change during hyperperfusion, but thickening in the subepicardial layer was increased by 14 +/- 3% with adenosine and 18 +/- 3% with adenosine plus TNG during the heaviest level of exercise (each P < 0.05). There was no difference in wall thickening between adenosine and adenosine plus TNG. These findings imply that the increases in MVo2 which occur during exercise are limited by coronary blood flow.

Nonuniform transmural recovery of contractile function in stunned myocardium

1989 ◽  
Vol 257 (2) ◽  
pp. H375-H385 ◽  
Author(s):  
R. Bolli ◽  
B. S. Patel ◽  
C. J. Hartley ◽  
J. I. Thornby ◽  
M. O. Jeroudi ◽  
...  
Keyword(s):  
Contractile Function ◽  
Recovery Of Function ◽  
Left Ventricular ◽  
Stunned Myocardium ◽  
Wall Thickening ◽  
Base Line ◽  
Doppler Probe ◽  
Group 2 ◽  
Systolic Wall Thickening ◽  
Group 1

With the use of an epicardial Doppler probe, systolic wall thickening was selectively measured in the inner, mid, and outer layers of the left ventricular (LV) wall in 16 conscious dogs undergoing a 15-min left anterior descending artery (LAD) occlusion followed by 7 days of reperfusion (REP). Under control conditions, percent thickening fraction (ThF) was significantly greater (P less than 0.01) in the inner layer [36.0 +/- 2.3% (mean +/- SE)] than in the mid (28.6 +/- 2.1%) or outer (21.3 +/- 2.2%) layers. During LAD occlusion, 11 dogs exhibited transmural dyskinesis (group 1), whereas 5 had transmural hypokinesis (group 2). In group 1, all layers exhibited comparable degrees of paradoxical systolic thinning during LAD occlusion. After REP, however, recovery was delayed in the inner compared with the mid and outer layers. At 2 h, ThF averaged 34.2 +/- 11.9% of base line in the endocardium vs. 61.7 +/- 16.2% in the midmyocardium and 51.0 +/- 12.3% in the epicardium (F = 4.29, P less than 0.002); similar differences were noted at 3 and 4 h. In the mid and outer layers, ThF returned to base-line values by 24 h, whereas in the inner layer it was still significantly depressed (P less than 0.05) at 24 h (77.3 +/- 5.1% of base line) and recovered by 48 h. The inner-to-outer ThF ratio was decreased (P less than 0.01) for 24 h after REP, indicating maldistribution of thickening in the "stunned" myocardium. In group 2, all layers exhibited hypokinesis during LAD occlusion. Again, recovery of function after REP was delayed in the endocardium compared with the other layers. This study demonstrates that after both severe ischemia resulting in dyskinesis and mild ischemia resulting in hypokinesis, REP is associated with slower recovery of function in the inner than in the outer layers. Thus myocardial "stunning" is a nonuniform phenomenon with maximal severity in the subendocardium.

Myocardial bioenergetics during acute hibernation

1997 ◽  
Vol 273 (3) ◽  
pp. H1452-H1463 ◽  
Author(s):  
J. Zhang ◽  
Y. Ishibashi ◽  
Y. Zhang ◽  
M. H. Eijgelshoven ◽  
D. J. Duncker ◽  
...  
Keyword(s):  
Blood Flow ◽  
Contractile Function ◽  
Creatine Phosphate ◽  
Wall Thickening ◽  
Resonance Spectroscopy ◽  
Blood Flow Ratio ◽  
Ischemic Period ◽  
Myocardial O2 Consumption ◽  
Final Extent ◽  
Myocardial Bioenergetics

During moderate reductions of blood flow, the myocardium downregulates contractile function and ATP utilization to result in reduced but stable ATP levels, recovery or stability of (reduced) creatine phosphate (CP), and preservation of myocyte viability. The intent of this study was to determine the influence of the level of ischemic blood flow and the major determinants of myocardial O2 consumption (MVO2) (heart rate and systolic blood pressure) on recovery of CP during prolonged moderate myocardial hypoperfusion. 31P-nuclear magnetic resonance spectroscopy was used to measure CP, ATP, and Pi in the subepicardium (Epi) and subendocardium (Endo) of 13 open-chest dogs. Wall thickening was measured with sonomicrometry. A coronary stenosis reduced mean myocardial blood flow (microspheres) from 1.10 +/- 0.07 to 0.71 +/- 0.06 ml.g-1.min-1 (P < 0.01) and the Endo-to-Epi blood flow ratio from 1.12 +/- 0.07 to 0.59 +/- 0.06 (P < 0.01), and dyskinesis developed. Coronary blood flow and systolic wall thickening did not change significantly during 4 h of hypoperfusion. Epi CP and ATP fell to 80 +/- 4% (P < 0.05) and 93 +/- 3% of control, respectively, at 30 min. Epi CP then recovered to 87 +/- 5% while ATP decreased further to 83 +/- 5% of baseline by the end of the 240-min ischemic period. Endo CP and ATP fell to 53 +/- 4 and 77 +/- 5% of control, respectively, at 30 min; then Endo CP recovered to 85 +/- 6% while ATP decreased further to 68 +/- 6% of baseline at 240 min of hypoperfusion. ADP levels were significantly increased at 30 min but recovered to baseline by 240 min of hypoperfusion. delta Pi/CP increased significantly (Endo > Epi) at the onset of ischemia and then progressively decreased. At 30 min, mild myocardial acidosis was observed in some hearts with variable pH recovery during continuing hypoperfusion. The data demonstrate that variations in blood flow cannot account for the magnitude of the initial fall in CP or for the final extent of recovery. However, the rate at which CP recovered was significantly correlated with the level of blood flow. Variations in the determinants of MVO2 did not account for differences in CP recovery.

scholarly journals Clinical and functional characteristics of children with ventricular arrhythmias depending on the ectopic focus localization

2021 ◽  
Vol 28 (4) ◽  
pp. 15-23
Author(s):  
O. V. Yeliseyeva
Keyword(s):  
Sinus Rhythm ◽  
Ventricular Arrhythmias ◽  
Contractile Function ◽  
Electrophysiological Study ◽  
Stress Test ◽  
Structural Heart Disease ◽  
Holter Monitoring ◽  
Free Wall ◽  
Functional Features ◽  
The Right

Aim. To determine the prevalence of ventricular arrhythmias (VA) among children with cardiac arrhythmias and to assess the clinical, functional, and electrophysiological characteristics of VA, depending on the localization of the ectopic focus.Methods. The study included 260 children, 153 (58,8%) boys, the mean age of patients was 13.4±3.1years. Based on clinical and anamnestic data, ECG, Holter monitoring, echocardiography, dosed exercise test, invasive electrophysiological study (EPS), radiofrequency ablation (RFA) a comparative assessment of the clinical and functional features of the most frequently diagnosed localizations of the ectopic focus in children with VA was carried out according to the data of invasive EPS, RFA.Results. According to invasive EPI, the most frequent localization of VA in children is the right ventricle outflow tract (RVOT) - 144 (55%), less often - the Valsalva sinuses - 52 (20%) and the RV free wall - 47 (18%). In most cases (255 children, 98%) there was a focal arrhythmia (trigger activity). The localization of ectopia in the RV free wall is characterized by the predominance of single ventricular premature beats (VPB) or in combination with a paired VPB (78,7%) and polymorphism of ventricular complexes (30%). The peculiarity of ventricular tachycardia in this localization is its stable character (17,0%) and low heart rate in volleys (idioventricular rhythm) (12,8%). When the focus was localized in the RVOT, as well as when it was localized in the RV free wall, single VPB or in combination with paired VPB prevailed (84,7%), but polymorphism of ventricular complexes was less often observed (10,4%). Differences in myocardial contractility at the sinus rhythm in right ventricular arrhythmias were revealed. Thus, the ejection fraction at the localization of the lesion in the RV free wall was significantly lower than in the RVOT (63.4±5.5% and 65.8±5.9%, respectively; p<0.01). Hemodynamic significance is characteristic for RV arrhythmias (21.3% and 16.0% of patients) and was practically not observed at the left-sided localization of the arrhythmogenic focus (3.8%; p<0.01). VA in patients without structural heart disease, regardless of the localization of the arrhythmic focus in children, is asymptomatic and is detected, in most cases, within the framework of clinical examination 206 patients, 79.2%. The prevalence of syncope in children with idiopathic VA is 15.8% (41 patients), and in most cases, they are of vaso-vagal origin. In most children (178, 70%), idiopathic VA is dependent on the level of parasympathetic influences on the heart, disappearing or significantly decreasing during exercise, which is revealed during the stress test confirming the high role of autonomic influences on the regulation of heterotopic rhythm in children with VA.Conclusion. VA is a common arrhythmia in children. Depending on the localization of the arrhythmogenic focus, characteristic features of the structure and density of the heart, as well as differences in the contractile function of the myocardium on the sinus rhythm and on the ectopic complex were revealed.

4934Biventricular global and regional strain measured by cardiovascular magnetic resonance based tissue tracking

2019 ◽  
Vol 40 (Supplement_1) ◽  
Author(s):  
Y Qu ◽  
D Buckert ◽  
G S Ma ◽  
V Rasche
Keyword(s):  
Reference Values ◽  
Contractile Function ◽  
Three Dimensional ◽  
Reference Value ◽  
Wall Thickening ◽  
Specific Reference ◽  
Peak Strain ◽  
Clinical Routine ◽  
Tissue Tracking ◽  
Global Peak

Abstract Background CMR based tissue tracking (CMR-TT), considered as a novel modality, provides additional insight into left and right ventricular (LV/RV) mechanical function and deformation. The vendor-specific reference values of global and regional strains for volunteers without history of cardiovascular disease are necessary as an important step in clinical routine to help detect early abnormality. Purpose To determine the reference value of LV/RV multi-dimensional global and segmental strains and diagnostic specificity of global longitudinal peak strain (GLS). Biventricular global and segmental radial, circumferential and longitudinal systolic peak strains (GRS, GCS, GLS and SRS, SCS, SLS) of 150 healthy adults in three age subgroups (G20–40, G41–60 and G61–80) were derived by post-hoc imaging software in standard steady-state free precession cine images acquired at 1.5T. LV strains were calculated with three-dimensional (3D) CMR-TT in the modified AHA 16-segment model via a short-axis stack and long axis 2-, 3-, 4-chamber cine images, and RV strains were generated with 2D CMR-TT via 4-chamber cine images. Results The reference values of LV global peak strains resulted as 44.4±13.0% for GRS, −17.0±2.7% for GCS, and −15.4±2.3% for GLS, respectively. RV-GLS was measured as −24.9±5.1%. Global and segmental strains might differ between males and females. Females showed significant age-associated difference of LV global peak strains (P<0.05) as the opposite of males (Figure 1). Females also presented higher magnitude of LV global peak strains than males in the eldest group G61–80 (P<0.05). Unlike LV, no age-associated difference of RV-GLS was detected in both gender groups. However, females showed less negative RV-GLS than males in G20–40 and more negative RV-GLS than males older than 40 years old (P<0.05). The local discrepancy of biventricular SRS, SCS and SLS was observed. It seemed that LV mid-cavity played a more essential role on LV shortening (more negative SCS and SLS) than wall thickening (smaller SRS) compared with base and apex. RV basal and mid SLS, derived from segment 1–4, was more negative than apical SLS derived from segment 5–6. The specificity of LV- and RV-GLS cut-off value (mean value+1.96*standard deviation) generated from the vendor-, age- and gender-specific reference value in evaluating heart contractile function reached 97.3% and 94.7%, respectively. Conclusions Considering the vendor-, gender- and age-associated difference of biventricular global strains, specific reference values need to be established to facilitate the wide application of strain in clinical routine. Meanwhile, segmental strains are also fundamental for detecting local abnormality of myocardial deformation.

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