P6484Invasive and non-invasive characterisation of low gradient aortic stenosis

2019 ◽  
Vol 40 (Supplement_1) ◽  
Author(s):  
H Z R McConkey ◽  
M Marber ◽  
J Lee ◽  
H Ellis ◽  
J Joseph ◽  
...  
Keyword(s):  
Aortic Stenosis ◽  
Research Training ◽  
Augmentation Index ◽  
Myocardial Perfusion Reserve ◽  
Systolic Pressure ◽  
Left Ventricular ◽  
Volume Index ◽  
Stress Perfusion ◽  
Stroke Work ◽  
Rapid Pacing

Abstract Background Low gradient severe aortic stenosis (LGAS) is associated with unfavourable outcomes when compared to high gradient aortic stenosis (HGAS), yet the contributing pathophysiology is poorly understood. Methods Symptomatic LGAS and HGAS patients undergoing trans-catheter aortic valve implantation (TAVI) underwent 3T stress perfusion cardiac magnetic resonance imaging (CMR) pre-(within 24 hours) and post-(4–6 months) TAVI. Left ventricular (LV) contractility and coronary flow/pressure were measured during hyperaemia and rapid pacing, immediately before and after TAVI, using a conductance LV catheter and dual-pressure and Doppler sensor–tipped guidewire in the mid-left anterior descending coronary artery. Results 24 patients were recruited resulting in 19 suitable datasets (LGAS N=9, HGAS N=10, equally matched for comorbidities and B-natriuretic peptide level). LGAS patients had a smaller LV end diastolic volume index (p=0.035) and lower LV mass index (LVMI) (p=0.037). Pre-TAVI stress global endocardium-epicardium gradient was 0.88±0.09 and global myocardial perfusion reserve (MPR) 2.0±0.48 in 14 patients (6 LGAS and 8 HGAS patients, no difference between groups). Pre-TAVI, baseline coronary data demonstrated lower augmentation pressure (AP, p=0.035) and augmentation index (AIx, p=0.02) in the LGAS group. LGAS patients also exhibited a shorter ejection time (p=0.015), larger forward compression waves during rest, hyperaemia and rapid pacing, and smaller backward expansion waves (BEW) (p=0.001). Lower baseline end systolic pressure (p=0.004), inotropy (dP/dt+, p=0.045), lusitropy (dP/dt-, p=0.069), and stroke work (p=0.019) were observed in the LGAS group. Whilst LV size was smaller the LGAS group, rapid pacing induced a more significant drop in end systolic volume (p=0.045) and ejection fraction (p=0.015) in patients with HGAS. Post-TAVI, the hyperaemic BEW fell sharply (p<0.001), along with coronary VTI (p=0.02), and average pulse velocity (p=0.028), and AP and AIx remained lower (p=0.034 and p=0.031, respectively). The forward expansion wave was reduced in LGAS during rapid pacing. The HGAS group displayed a more profound drop in dP/dt+ (p=0.011) and dP/dt- p=0.014) at rest following intervention. Repeat CMR demonstrated statistically significant reduction in LV size and LVMI (p=0.012 and p<0.001, respectively) with significant increase in 3D global peak radial, circumferential and longitudinal strain (p=0.004, p=0.001 and p=0.018, respectively). Post-TAVI stress global endocardium-epicardium gradient was 0.88±0.13 and MPR 2.46±0.59 (improved from pre-TAVI, p=0.05). There was no difference in remodelling patterns or perfusion between the two groups. Conclusion This is the first study detailing the combined invasive and CMR pathophysiological changes in LGAS. Despite invasive parameters indicating a disease of less severe AS, the level of perfusion abnormality is disproportionate which may in part, relate to their adverse prognosis. Acknowledgement/Funding This research is funded by a Clinical Research Training Fellowship grant from the British Heart Foundation (FS/16/51/32365).

Left atrial dynamics in the hemodynamic response during exercise in patients with asymptomatic severe aortic stenosis: a cardiopulmonary imaging study

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
T Sugimoto ◽  
F Bandera ◽  
M Barletta ◽  
E Alfonzetti ◽  
M Guazzi
Keyword(s):  
Aortic Stenosis ◽  
Left Atrial ◽  
Cardiopulmonary Exercise Testing ◽  
Systolic Pressure ◽  
Stroke Volume Index ◽  
Left Ventricular ◽  
Low Flow ◽  
Volume Index ◽  
Aortic Valve Area ◽  
Significant Difference

Abstract Background The hemodynamic impact of left atrial (LA) dynamics in aortic stenosis (AS) in relation to cardiopulmonary response to exercise has never been studied. We aimed at investigating the link between LA function vs valvulo-arterial impedance (Zva) and right ventricular (RV)-to-pulmonary circulation (PC) coupling in asymptomatic severe AS patients. Methods A total of 94 patients: 64 asymptomatic severe AS patients (aortic valve area (AVA) &lt;1.0 cm2 or AVA index &lt;0.6 cm2/m2) with ejection fraction &gt;50% and 30 gender-matched control subjects underwent cardiopulmonary exercise testing combined with Echo-Doppler with assessment of LA strain and RV-to-PC coupling (tricuspid annular peak systolic excursion (TAPSE)/ pulmonary arterial systolic pressure (PASP) ratio). AS patients were divided into 3 groups according to peak aortic jet velocity (PV), mean pressure gradient (MPG) and stroke volume index (SVI). Zva was assessed using (MPG + systolic blood pressure)/ SVI ratio. Results Paradoxical low-flow low-gradient AS (PLFLG: PV &lt;4 m/s and MPG &lt;40 mmHg, SVI ≤35ml/m2, N=18, AVA 0.77±0.16 cm2), Normal-flow low-gradient AS (NFLG: PV &lt;4 m/s and MPG &lt;40 mmHg, SVI &gt;35ml/m2, N=23, AVA 0.85±0.16 cm2) and High-gradient AS (HG: PV ≥4 m/s or MPG ≥40 mmHg, N=20, AVA 0.62±0.17 cm2) had a higher LA volume index than Control (Control 22±6, PLFLG 33±11*, NFLG 38±12* and HG 33±9* ml/m2, *P&lt;0.05 vs Control). There was no significant difference in peak VO2 (17±5 ml/min/kg) and VE/VCO2 slope (28±3) among 3 AS groups although PLFLG had lower peak cardiac output (7.0±2.4 L/min) compared to NFLG (9.0±2.3 L/min) and HG (9.2±3.3 L/min). In PLFLG and NFLG AS, LA strain at rest (21±9 and 26±13%) and during exercise (26±12 and 31±14%) were decreased compared to Control (37±8% at rest, 43±11% during exercise) but maintained some reserve during exercise (P&lt;0.001). HG AS had no increase in LA strain (31±15% at rest, 28±15% during exercise) (Figure A). In AS groups, no significant correlation at rest was observed between LA strain and Zva, whereas a negative correlation was observed during exercise (R=−0.4, P=0.003, Figure B). LA strain was also correlated with TAPSE/PASP at rest and exercise (R=0.44 and 0.47, P&lt;0.01, respectively, Figure C). Conclusions In asymptomatic severe AS, the study of LA functional adaptation to exercise plays a key role in the hemodynamic unfavorable cascade from AS-related left ventricular afterload to RV-to-PC uncoupling. Funding Acknowledgement Type of funding source: None

Age-related left ventricular function in the mouse: analysis based on in vivo pressure-volume relationships

1999 ◽  
Vol 277 (5) ◽  
pp. H1906-H1913 ◽  
Author(s):  
Bo Yang ◽  
Douglas F. Larson ◽  
Ronald Watson
Keyword(s):  
Contractile Function ◽  
Systolic Pressure ◽  
Left Ventricular ◽  
Volume Index ◽  
Lv Function ◽  
Mouse Heart ◽  
Stroke Work ◽  
Arterial Elastance ◽  
Systolic Volume ◽  
End Systolic Volume

Our study compared left ventricular (LV) function between senescent and young adult mice through in situ pressure-volume loop analysis. Two groups of mice ( n = 9 each), 6-mo-old and 16-mo-old (senescent) mice, were anesthetized with urethan and α-chloralose, and their LV were instrumented with a Millar 1.4-Fr conductance micromanometer catheter for the acquisition of the pressure-volume loops. The senescent mice had a significantly decreased contractile function related to load-dependent parameters, including stroke volume index, ejection fraction, cardiac output index, stroke work index, and maximum derivative of change in systolic pressure over time. The load-independent parameters, preload recruitable stroke work and the slope (end-systolic volume elastance) of the end-systolic pressure-volume relationship, were significantly decreased in the senescent mice. Heart rate and arterial elastance were not different between the two groups; however, the ventricular-to-vascular coupling ratio (ratio of elastance of artery to end-systolic volume elastance) was increased by threefold in the senescent mice ( P < 0.001). Thus there were significant decreases in contractile function in the senescent mouse heart that appeared to be related to reduced mechanical efficiency but not related to arterial elastance.

scholarly journals 2363

2017 ◽  
Vol 1 (S1) ◽  
pp. 36-36
Author(s):  
Leo Buckley ◽  
Justin Canada ◽  
Salvatore Carbone ◽  
Cory Trankle ◽  
Michele Mattia Viscusi ◽  
...  
Keyword(s):  
Heart Failure ◽  
Blood Pressure ◽  
Stroke Volume ◽  
Systolic Pressure ◽  
Left Ventricular ◽  
Volume Index ◽  
Stroke Work ◽  
Systolic Volume ◽  
Arterial Blood ◽  
End Systolic Volume

OBJECTIVES/SPECIFIC AIMS: Our goal was to compare the ventriculo-arterial coupling and left ventricular mechanical work of patients with systolic and diastolic heart failure (SHF and DHF). METHODS/STUDY POPULATION: Patients with New York Heart Association Functional Class II-III HF symptoms were included. SHF was defined as left ventricular (LV) ejection fraction<50% and DHF as >50%. Analysis of the fingertip arterial blood pressure tracing captured with a finger plethysmography cuff according to device-specific algorithms provided brachial artery blood pressure and stroke volume. LV end-systolic volume was measured separately via transthoracic echocardiography. Arterial elastance (Ea), a measure of pulsatile and nonpulsatile LV afterload, was calculated as LV end-systolic pressure (ESP)/end-diastolic volume. End-systolic elastance (Ees), a measure of load-independent LV contractility, was calculated as LV ESP/end-systolic volume. Ventriculo-arterial coupling (VAC) ratio was defined as Ea/Ees. Stroke work (SWI) was calculated as stroke volume index×LV end-systolic pressure×0.0136 and potential energy index (PEI) as 1/2×(LV end-systolic volume×LV end-systolic pressure×0.0136). Total work index (TWI) was the sum of SWI+PEI. RESULTS/ANTICIPATED RESULTS: Patients with SHF (n=52) and DHF (n=29) were evaluated. Median (IQR) age was 57 (51–64) years. There were 48 (58%) and 59 (71%) patients were male and African American, respectively. Cardiac index was 2.8 (2.2–3.2) L/minute and 3.0 (2.8–3.3) L/minute in SHF and DHF, respectively (p=0.12). Self-reported activity levels (Duke Activity Status Index, p=0.48) and heart failure symptoms (Minnesota Living with Heart Failure Questionnaire, p=0.55) were not different between SHF and DHF. Ea was significantly lower in DHF compared with SHF patients [1.3 (1.2–1.6) vs. 1.7 (1.4–2.0) mmHg; p<0.001] whereas Ees was higher in DHF vs. SHF [2.8 (2.1–3.1) vs. 0.9 (0.7-1.3) mmHg; p<0.001). VAC was 1.8 (1.3–2.8) in SHF Versus 0.5 (0.4–0.7) in DHF (p<0.001). Compared with SHF, DHF patients had higher SWI [71 (57–83) vs. 48 (39–68) gm×m; p<0.001) and lower PEI [19 (12–26) vs. 44 (36–57) gm×m; p<0.001]. TWI did not differ between SHF and DHF (p=0.14). Work efficiency was higher in DHF than SHF [0.80 (0.74–0.84) vs. 0.53 (0.46–0.64); p<0.001]. DISCUSSION/SIGNIFICANCE OF IMPACT: The results underscore the differences in pathophysiology between SHF and DHF patients with similar symptom burden and exercise capacity. These results highlight the difference in myocardial energy utilization between SHF and DHF.

Applanation Tonometry for Assessment of Left Ventricular Systolic Load

2019 ◽  
Vol 12 (2) ◽  
pp. 94-99
Author(s):  
Rene D. Mileva-Popova ◽  
Nina Y. Belova
Keyword(s):  
Arterial Stiffness ◽  
Augmentation Index ◽  
Age Groups ◽  
Systolic Pressure ◽  
Left Ventricular ◽  
Applanation Tonometry ◽  
Non Invasive ◽  
Pressure Area ◽  
Older Subjects ◽  
And Gender

Summary Vascular-ventricular coupling is a major determinant of left ventricular load. The aim of our study was to assess non- invasively left ventricular load and its dependency on central hemodynamics. Sixty-five healthy and gender-matched individuals were divided in two groups according to their age: 20y/o and 50y/o. Applanation tonometry was performed using the Sphygmocor device. Central pressures and pulse wave analysis indices were computed. Central systolic (120±3 vs. 98±2 mm Hg) and pulse pressures (43±3 vs. 29±1 mm Hg) as well as the augmentation index (AIx75) (23±3 vs. 6±2%) were significantly higher in the 50y/o group (p<0.01). These parameters are relevant markers of arterial stiffness and evidenced the development of central arterial morphological and functional alterations in the older subjects. The time-tension index (TTI) computed from the systolic pressure area was significantly higher in the 50y/o subjects as compared to the 20y/o group (2378±66 vs. 1954±73 mmHg×s, p<0.01). Moreover, we have shown the presence of significant correlation between TTI and AIx75 (p<0.01) in both age groups. This finding confirmed the contribution of arterial stiffness for the impaired vascular-ventricular coupling. In conclusion, applanation tonometry might be utilized for non-invasive evaluation of the left ventricular load, which is an important parameter of cardiovascular risk.

Desflurane, Sevoflurane, and Isoflurane Impair Canine Left Ventricular-Arterial Coupling and Mechanical Efficiency

1996 ◽  
Vol 85 (2) ◽  
pp. 403-413 ◽  
Author(s):  
Douglas A. Hettrick ◽  
Paul S. Pagel ◽  
David C. Warltier
Keyword(s):  
Arterial Pressure ◽  
Myocardial Contractility ◽  
Minimum Alveolar Concentration ◽  
Systolic Pressure ◽  
Mechanical Efficiency ◽  
Left Ventricular ◽  
Stroke Work ◽  
Arterial Elastance ◽  
Ventricular Afterload ◽  
Left Ventricular Arterial Coupling

Background The effects of desflurane, sevoflurane, and isoflurane on left ventricular-arterial coupling and mechanical efficiency were examined and compared in acutely instrumented dogs. Methods Twenty-four open-chest, barbiturate-anesthetized dogs were instrumented for measurement of aortic and left ventricular (LV) pressure (micromanometer-tipped catheter), dP/dtmax, and LV volume (conductance catheter). Myocardial contractility was assessed with the end-systolic pressure-volume relation (Ees) and preload recruitable stroke work (Msw) generated from a series of LV pressure-volume diagrams. Left ventricular-arterial coupling and mechanical efficiency were determined by the ratio of Ees to effective arterial elastance (Ea; the ratio of end-systolic arterial pressure to stroke volume) and the ratio of stroke work (SW) to pressure-volume area (PVA), respectively. Results Desflurane, sevoflurane, and isoflurane reduced heart rate, mean arterial pressure, and left ventricular systolic pressure. All three anesthetics caused similar decreases in myocardial contractility and left ventricular afterload, as indicated by reductions in Ees, Msw, and dP/dtmax and Ea, respectively. Despite causing simultaneous declines in Ees and Ea, desflurane decreased Ees/Ea (1.02 +/- 0.16 during control to 0.62 +/- 0.14 at 1.2 minimum alveolar concentration) and SW/PVA (0.51 +/- 0.04 during control to 0.43 +/- 0.05 at 1.2 minimum alveolar concentration). Similar results were observed with sevoflurane and isoflurane. Conclusions The present findings indicate that volatile anesthetics preserve optimum left ventricular-arterial coupling and efficiency at low anesthetic concentrations (&lt; 0.9 minimum alveolar concentration); however, mechanical matching of energy transfer from the left ventricle to the arterial circulation degenerates at higher end-tidal concentrations. These detrimental alterations in left ventricular-arterial coupling produced by desflurane, sevoflurane, and isoflurane contribute to reductions in overall cardiac performance observed with these agents in vivo.

Pressure-Volume Relationship By Pharmacological Stress Cardiovascular Magnetic Resonance

2021 ◽  
Author(s):  
Antonella Meloni ◽  
Antonio De Luca ◽  
Cinzia Nugara ◽  
Maria Vaccaro ◽  
Camilla Cavallaro ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Characteristic Curve ◽  
Systolic Pressure ◽  
Left Ventricular ◽  
Volume Index ◽  
Cardiac Events ◽  
Pharmacological Stress ◽  
Systolic Volume ◽  
Stress Cmr ◽  
Dipyridamole Stress

Abstract Background. The variation between rest and peak stress end-systolic pressure-volume relation (ΔESPVR) is an index of myocardial contractility, easily obtained during routine stress echocardiography and never tested during dipyridamole stress-cardiac magnetic resonance (CMR). We assessed the ΔESPVR index in patients with known/suspected coronary artery disease (CAD) who underwent dipyridamole stress-CMR.Methods. One-hundred consecutive patients (24 females, 63.76±10.17 years) were considered. ESPVR index was evaluated at rest and stress from raw measurement of systolic arterial pressure and end-systolic volume by biplane Simpson’s method. Results. The ΔESPVR index showed a good inter-operator reproducibility. Mean ΔESPVR index was 0.48±1.45 mmHg/mL/m2. ΔESPVR index was significantly lower in males than in females. ΔESPVR index was not correlated to rest left ventricular end-diastolic volume index or ejection fraction. Forty-six of 85 patients had myocardial fibrosis detected by the late gadolinium enhancement technique and they showed significantly lower ΔESPVR values. An abnormal stress CMR was found in 25 patients and they showed significantly lower ΔESPVR values. During a mean follow-up of 56.34±30.04 months, 24 cardiovascular events occurred. At receiver-operating characteristic curve analysis, a ΔESPVR<0.02 mmHg/mL/m2 predicted the presence of future cardiac events with a sensitivity of 0.79 and a specificity of 0.68. Conclusions. The noninvasive assessment of the ΔESPVR index during a dipyridamole stress-CMR exam is feasible and reproducible. The ΔESPVR index was independent from rest LV dimensions and function and can be used for a comparative assessment of patients with different diseases. ΔESPVR by CMR can be a useful and simple marker for additional prognostic stratification.

Left ventricular-arterial coupling in conscious dogs

1991 ◽  
Vol 261 (1) ◽  
pp. H70-H76 ◽  
Author(s):  
W. C. Little ◽  
C. P. Cheng
Keyword(s):  
Stroke Volume ◽  
Systolic Pressure ◽  
Left Ventricular ◽  
Arterial System ◽  
Conscious Dogs ◽  
Stroke Work ◽  
Arterial Elastance ◽  
Inotropic State ◽  
End Diastolic Volume ◽  
Wide Range

We investigated the criteria for the coupling of the left ventricle (LV) and the arterial system to maximize LV stroke work (SW) and the transformation of LV pressure-volume area (PVA) to SW. We studied eight conscious dogs that were instrumented to measure LV pressure and determine LV volume from three ultrasonically determined dimensions. The LV end-systolic pressure (PES)-volume (VES) relation was determined by caval occlusion. Its slope (EES) was compared with the arterial elastance (EA) and determined as PES per stroke volume. At rest, with intact reflexes, EES/EA was 0.96 +/- 0.20 EES/EA was varied over a wide range (0.18-2.59) by the infusion of graded doses of phenylephrine and nitroprusside before and during administration of dobutamine. Maximum LV SW, at constant inotropic state and end-diastolic volume (VED), occurred when EES/EA equaled 0.99 +/- 0.15. At constant VED and contractile state, SW was within 20% of its maximum value when EES/EA was between 0.56 and 2.29. The conversion of LV PVA to SW increased as EES/EA increased. The shape of the observed relations of the SW to EES/EA and SW/PVA to EES/EA was similar to that predicted by the theoretical consideration of LV PES-VES and arterial PES-stroke volume relations. We conclude that the LV and arterial system produce maximum SW at constant VED when EES and EA are equal; however, the relation of SW to EES/EA has a broad plateau. Only when EA greatly exceeds EES does the SW fall substantially. However, the conversion of PVA to SW increases as EES/EA increases. These observations support the utility of analyzing LV-arterial coupling in the pressure-volume plane.

scholarly journals P1370 Correlation of aortic stenosis by integrated transthoracic and transesophageal echocardiography with calcium score

2020 ◽  
Vol 21 (Supplement_1) ◽  
Author(s):  
S Schwartzenberg ◽  
Y Shapira ◽  
M Vaturi ◽  
M Nassar ◽  
A Hamdan ◽  
...  
Keyword(s):  
Aortic Valve ◽  
Aortic Stenosis ◽  
Stroke Volume Index ◽  
Left Ventricular ◽  
Low Flow ◽  
Volume Index ◽  
Left Ventricular Ejection ◽  
Aortic Valve Area ◽  
Ventricular Ejection Fraction ◽  
Coronary Ct

Abstract Funding Acknowledgements None BACKGROUND Aortic stenosis (AS) classification depends on left-ventricular ejection-fraction (LVEF &lt;≥50%), aortic valve area (AVA&lt;≥1cm2), mean pressure gradient (MG&lt;≥40mmHg), peak velocity&lt;≥400 cm/sec, and stroke-volume index (SVI&lt;≥35ml/m2). Aortic Valve Agatston CT score (AVC) correlates with AS severity by trans-thoracic echo (TTE), but its association with AS severity determined by integrated TTE and TEE is unknown. PURPOSE We investigated correlation of AVC with dichotomous AS grouping by Integrated TTE + TEE vs TTE only. METHODS 64 TAVI candidates underwent sequential TTE and TEE, of which 24 underwent coronary CT within 4 months. Based on recommended conservative vs invasive treatment implication (A/B respectively), AS types were aggregated separately by TTE or Integrated TTE-TEE into two groups: Group-A (Moderate AS and Normal-Flow Low-Gradient), and Group-B (High-Gradient, Low-EF Low-Flow Low-Gradient, and Paradoxical Low-Flow Low-Gradient). Continuous and dichotomous AVC correlation (cutoffs based on guidelines) with echo binary classification was then determined. RESULTS Patients were 81.1(77.3-84.6) years old, 18(48.6%) were women, and had LVEF of 60% (49-65). AVC-score distribution in the two AS A/B Groups by two echo modalities is presented in the boxplot Figure. Only classification by TTE held discriminative accuracy in A/B grouping, with Area-Under-Curve of 0.736 (CI 0.57-0.9), and optimal threshold value of 1946 AU having 77% sensitivity and 74% specificity. Compared with AVC dichotomous classification, integrated TTE + TEE upgraded AS class (from A to B) in 5/6 (83.3%) patients vs 12/18 (66.7%) in which it downgraded AS class from B to A. CONCLUSIONS Aortic valve calcification correlates well with AS class dichotomized by operative implication through conventional TTE but not through integrated TTE + TEE. Our preliminary results appear to be caused by initial selection bias of patients in whom coronary CT performance was deemed to be justified by the treating physician rather than reflect a true better correlation between CT score and AS assessment by TTE vs by integrated TTE + TEE. Abstract P1370 Figure.

Optimal matching between canine left ventricle and afterload

1988 ◽  
Vol 254 (6) ◽  
pp. H1051-H1058
Author(s):  
E. S. Myhre ◽  
A. Johansen ◽  
H. Piene
Keyword(s):  
Systolic Pressure ◽  
Left Ventricular ◽  
Right Atrial ◽  
Stroke Work ◽  
External Work ◽  
Volume Load ◽  
Before And After ◽  
Anesthetized Dogs ◽  
Pressure Volume Relationship ◽  
Optimal Values

A parabolic relationship exists between ventricular external work and arterial load at given preload and contractility. Previous data indicate that the working point falls close to the parabola optimum. By combining the left ventricular (LV) end-systolic pressure-volume relationship (ESPVR) and an equation describing external stroke work, optimum values of stroke volume (SV), the slope (Emax) of the ESPVR, and arterial resistance (Rp) corresponding with the optimum (i.e., mSV, mEmax, mRp) were obtained. Experiments in anesthetized dogs were performed to test whether mSV, mEmax, and mRp also correspond to observed SV, Emax, and Rp at three different levels of volume load (right atrial pressure, RAP) before and after acute depression of LV contractility. Comparisons of observed and optimal values of SV, Emax, and Rp were made before and after LV depression. Before embolization, the ratios were SV/mSV 1.10–1.20 (RAP 5–15 mmHg); Emax/mEmax 1.21–1.41; and Rp/mRp 0.84–0.69. After LV depression, SV/mSV was 0.80–0.83, Emax/mEmax was 0.78–0.71, and Rp/mRp was 1.56–1.46. The ratios were all significantly changed (P less than 0.01) by the induced LV depression. The present analysis may offer a new tool to detect nonoptimal relations between cardiac and arterial functions.

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.

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