Contribution of systemic arterial compliance and systemic vascular resistance to effective arterial elastance changes during exercise in humans

The respective contribution of systemic vascular resistance ( R) and total arterial compliance ( C) to the arterial load remains to be established in humans. Effective arterial elastance ( Ea), i.e., the left ventricular end-systolic pressure (LVESP)-over-stroke volume ratio, is a reliable estimate of arterial load. It is widely accepted that Ea mainly relates to mean aortic pressure (MAP) and thus to the R-to- T ratio ( R/ T ratio), where T is cycle length. We tested the contribution of R/ T and 1/ C to Ea in 20 normotensive and 46 hypertensive subjects (MAP range: 84–160 mmHg). The multilinear model applied ( Ea = 1.00 R/ T + 0.42/ C – 0.04; r2 = 0.97). The sensitivity of Ea to a change in R/ T was 2.5 times higher than to a similar change in 1/ C in both normotensive and hypertensive adults. The LVESP was more strongly related to systolic aortic pressure (SAP; r2 = 0.94) than to MAP ( r2 = 0.83), and LVESP matched 90% SAP (bias = 0 ± 5mmHg). An alternative model of Ea is proposed, in which Ea is proportional to the heart rate × SAP product-over-cardiac index ratio whatever the MAP.

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Systemic arterial compliance, systemic vascular resistance, and effective arterial elastance during exercise in endurance-trained men

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00009.2008 ◽

2008 ◽

Vol 295 (1) ◽

pp. R228-R235 ◽

Cited By ~ 18

Author(s):

Takeshi Otsuki ◽

Seiji Maeda ◽

Motoyuki Iemitsu ◽

Yoko Saito ◽

Yuko Tanimura ◽

...

Keyword(s):

Oxygen Uptake ◽

Vascular Resistance ◽

Maximal Oxygen Uptake ◽

Doppler Ultrasonography ◽

Arterial Compliance ◽

Left Ventricular ◽

Dependent Manner ◽

Arterial Elastance ◽

Effective Arterial Elastance ◽

The Difference

Systemic arterial compliance (C) and vascular resistance (R) regulate effective arterial elastance (Ea), an index of artery load. Increases in Ea during exercise are due primarily to reductions of C and maintain optimal ventricular-arterial coupling. Because C at rest and left ventricular functional reserve are greater in endurance-trained (ET) compared with sedentary control (SC) humans, we hypothesized that reductions of C and increases in Ea are greater in ET than SC individuals. The aim of this study was to investigate C, R, and Ea during exercise in ET and SC humans. C, R, Ea, and cardiac cycle length (T) were measured at rest and during exercise of 40, 60, and 80% maximal oxygen uptake using Doppler ultrasonography in 12 SC and 13 ET men. C decreased in an exercise intensity-dependent manner in both groups, but its reductions were greater in the ET than SC subjects. Consequently, although C at rest was greater in the ET than SC group, the intergroup difference in C disappeared during exercise. Exercise-related changes in R/T were relatively slight and R/T was lower in the ET than the SC group, both at rest and during exercise. Although Ea at rest was lower in the ET than SC group, there were no intergroup differences in Ea at 40, 60, or 80% maximal oxygen uptake. We conclude that the reductions of C from rest to exercise are more marked in ET than SC humans. This may be related to the exercise-associated disappearance of the difference in Ea between ET and SC humans.

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Contribution of Arterial Compliance and Vascular Resistance to Effective Arterial Elastance Changes During Exercise

Medicine & Science in Sports & Exercise ◽

10.1249/00005768-200605001-01709 ◽

2006 ◽

Vol 38 (Supplement) ◽

pp. S185

Author(s):

Takeshi Otsuki ◽

Seiji Maeda ◽

Motoyuki Iemitsu ◽

Yoko Saito ◽

Yuko Tanimura ◽

...

Keyword(s):

Vascular Resistance ◽

Arterial Compliance ◽

Arterial Elastance ◽

Effective Arterial Elastance

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Relaxin Modifies Systemic Arterial Resistance and Compliance in Conscious, Nonpregnant Rats

Endocrinology ◽

10.1210/en.2003-1612 ◽

2004 ◽

Vol 145 (7) ◽

pp. 3289-3296 ◽

Cited By ~ 93

Author(s):

Kirk P. Conrad ◽

Dan O. Debrah ◽

Jackie Novak ◽

Lee A. Danielson ◽

Sanjeev G. Shroff

Keyword(s):

Systemic Vascular Resistance ◽

Vascular Resistance ◽

Therapeutic Potential ◽

Muscle Tone ◽

Arterial Compliance ◽

Renal Arteries ◽

Conscious Rat ◽

Systemic Hemodynamic ◽

Arterial Load ◽

Passive Mechanics

Abstract Relaxin emanates from the corpus luteum of the ovary and circulates during pregnancy. Because the hormone is a potent renal vasodilator and mediates the renal vasodilation and hyperfiltration of pregnancy in conscious rats, we reasoned that it might also contribute to the broader cardiovascular changes of pregnancy. We began investigating this concept by testing whether relaxin can modify systemic arterial hemodynamics and load when chronically administered to nonpregnant rats. The major objectives of the present work were to determine whether relaxin administration to nonpregnant rats 1) modifies cardiac output (CO), systemic vascular resistance, and global arterial compliance (AC), and 2) regulates the passive mechanics of isolated arteries. To accomplish the first objective, we developed a conscious rat model for assessment of global AC. Passive mechanics of small renal arteries were assessed using a pressure arteriograph. Chronic administration of recombinant human relaxin by sc osmotic minipump to conscious, female, nonpregnant rats reduced the steady arterial load by decreasing systemic vascular resistance, increased CO, and reduced the pulsatile arterial load by increasing global AC as quantified by two indices—AC estimated from the diastolic decay of aortic pressure and CO and AC estimated by the ratio of stroke volume-to-pulse pressure. In another group of rats, relaxin administration also regulated the passive mechanics of small renal arteries, indicating that, in addition to reduction in vascular smooth muscle tone, modification of the vascular structure (e.g. extracellular matrix) contributes to the increase in global AC. These findings suggest a role for relaxin in the systemic hemodynamic changes of pregnancy, as well as novel therapeutic potential for relaxin in modifying arterial stiffness and cardiac afterload.

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Effect of Beta-adrenergic Blockade on Elevated Arterial Compliance and Low Systemic Vascular Resistance in Cirrhosis

Scandinavian Journal of Gastroenterology ◽

10.1080/00365520120440 ◽

2001 ◽

Vol 36 (6) ◽

pp. 653-657

Author(s):

S. Møller, F. Bendtsen, J. H. Henri

Keyword(s):

Systemic Vascular Resistance ◽

Vascular Resistance ◽

Arterial Compliance ◽

Adrenergic Blockade ◽

Beta Adrenergic

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Abstract 15631: The Hemodynamic Determinants and Physiologic Correlates of QTc Interval Using Impedance Cardiography in Heart Failure

Circulation ◽

10.1161/circ.132.suppl_3.15631 ◽

2015 ◽

Vol 132 (suppl_3) ◽

Author(s):

Fadi Khraim ◽

Rodolfo Pike ◽

Jennifer Williams ◽

Salah S Al-Zaiti

Keyword(s):

Heart Failure ◽

Systemic Vascular Resistance ◽

Vascular Resistance ◽

Impedance Cardiography ◽

Arterial Compliance ◽

Qtc Interval ◽

Cardiac Events ◽

Heart Failure Patients ◽

Qrs Duration ◽

Duration Effect

Background: Prolonged QTc interval is a known risk factor for adverse cardiac events, including sudden and non-sudden cardiac death. Understanding the determinants and physiologic correlates of QTc can guide the proper strategy for the primary prevention of sudden death in high risk patients. Methods & Results: This was an observational study that recruited ambulatory heart failure patients (NYHA I-III) from an outpatient clinic in NL, Canada. In supine resting position, consented participants underwent non-invasive 12-lead ECG and hemodynamic monitoring using BioZ Dx Impedance Cardiography (Sonosite Inc., WA, USA). ECGs were evaluated by a reviewer blinded to clinical data. Participants with pacing (n=12) or left bundle branch block (n=9) were excluded. Three measures of interest were automatically computed: (1) QTc interval (i.e., from QRS onset to T offset), (2) QRS duration (i.e., from QRS onset to QRS offset), and (3) JTc (i.e., QTc interval minus QRS duration). Effect sizes were computed using Pearson’s r coefficients. The final sample (n=23) was 62±13 years of age and 70% male with LVEF of 34±10%. The mean QTc was 441±39 milliseconds, and 10 patients (43%) had prolonged QTc (≥450 milliseconds). QTc interval negatively correlated with cardiac output (r= -0.57), and positively correlated with systemic vascular resistance (r= +0.57), as well as thoracic fluid content (r= +0.43). QRS duration alone was not specifically associated with any hemodynamic parameter, but JTc interval positively correlated with total arterial compliance (r=+0.42). Conclusions: In heart failure patients, we interestingly found that increased systemic vascular resistance results in QTc interval prolongation, where repolarization time is specifically influenced by arterial compliance. This suggests potential benefit from antihypertensive therapy targeted at lowering systemic vascular resistance in those with prolonged QTc/JTc. Nevertheless, these intervals need to be interpreted with caution in patients with thoracic fluid overload (e.g., pulmonary edema).

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Hemodynamic correlates of effective arterial elastance in mitral stenosis before and after balloon valvotomy

Journal of Applied Physiology ◽

10.1152/jappl.1997.83.4.1083 ◽

1997 ◽

Vol 83 (4) ◽

pp. 1083-1089 ◽

Cited By ~ 4

Author(s):

Patrice Colin ◽

Michel Slama ◽

Alec Vahanian ◽

Yves Lecarpentier ◽

Gilbert Motté ◽

...

Keyword(s):

Mitral Stenosis ◽

Arterial Compliance ◽

Aortic Pressure ◽

Pulse Interval ◽

Wave Reflections ◽

Arterial Elastance ◽

Before And After ◽

Hydraulic Load ◽

Balloon Valvotomy ◽

Effective Arterial Elastance

Colin, Patrice, Michel Slama, Alec Vahanian, Yves Lecarpentier, Gilbert Motté, and Denis Chemla. Hemodynamic correlates of effective arterial elastance in mitral stenosis before and after balloon valvotomy. J. Appl. Physiol. 83(4): 1083–1089, 1997.—This study had the purpose of documenting the hemodynamic correlates of effective arterial elastance (Ea; i.e., an accurate estimate of hydraulic load) in mitral stenosis (MS) patients. The main hypothesis tested was that Ea relates to the total vascular resistance (R)-to-pulse interval duration ( T) ratio (R/ T) in MS patients both before and after successful balloon mitral valvotomy (BMV). High-fidelity aortic pressure recordings were obtained in 10 patients (40 ± 12 yr) before and 15 min after BMV. Ea value was calculated as the ratio of the steady-state end-systolic aortic pressure (ESAP) to stroke volume (thermodilution). Ea increased after BMV (from 1.55 ± 0.63 to 1.83 ± 0.71 mmHg/ml; P < 0.05). Throughout the procedure, there was a strong linear relationship between Ea and R/ T: Ea = 1.09R/ T − 0.01 mmHg/ml, r = 0.99, P = 0.0001. This ultimately depended on the powerful link between ESAP and mean aortic pressure [MAP; r = 0.99, 95% confidence interval for the difference (MAP − ESAP) from −18.5 to +4.5 mmHg]. Ea was also related to total arterial compliance (area method) and to wave reflections (augmentation index), although to a lesser extent. After BMV, enhanced and anticipated wave reflections were observed, and this was likely to be explained by decreased arterial compliance. The present study indicated that Ea depended mainly on the steady component of hydraulic load (i.e., R) and on heart period (i.e., T) in MS patients.

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Peripheral circulatory control of preload-afterload mismatch with angiotensin in dogs

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1987.253.1.h126 ◽

1987 ◽

Vol 253 (1) ◽

pp. H126-H132

Author(s):

R. W. Lee ◽

L. D. Lancaster ◽

D. Buckley ◽

S. Goldman

Keyword(s):

Heart Rate ◽

Cardiac Output ◽

Stroke Volume ◽

Systemic Vascular Resistance ◽

Vascular Resistance ◽

Arterial Compliance ◽

Peripheral Circulation ◽

Aortic Pressure ◽

Venous Compliance ◽

Mean Aortic Pressure

To determine whether changes in the venous circulation were responsible for preload-afterload mismatch with angiotensin, we examined the changes in the heart and the peripheral circulation in six splenectomized dogs after ganglion blockade during an angiotensin infusion to increase mean aortic pressure 25 and then 50%. The peripheral circulation was evaluated by measuring mean circulatory filling pressure (MCFP), arterial compliance, and venous compliance. A 25% increase in mean aortic pressure increased MCFP from 6.2 +/- 0.3 to 7.6 +/- 0.3 mmHg (P less than 0.001) but did not change cardiac output, heart rate, or stroke volume. Systemic vascular resistance increased (P less than 0.01) from 0.50 +/- 0.02 to 0.59 +/- 0.03 mmHg X min X kg X ml-1. Arterial and venous compliances decreased (P less than 0.01) from 0.08 +/- 0.03 to 0.06 +/- 0.03 ml X mmHg-1 X kg-1 and from 2.1 +/- 0.1 to 1.6 +/- 0.1 ml X mmHg-1 X kg-1, respectively. A 50% elevation in mean aortic pressure increased MCFP from 7.1 +/- 0.4 to 9.5 +/- 0.9 mmHg (P less than 0.001) but did not change heart rate. At this level of aortic pressure, cardiac output and stroke volume decreased (P less than 0.01) 12 and 19%, respectively, whereas systemic vascular resistance increased (P less than 0.001) from 0.48 +/- 0.03 to 0.83 +/- 0.05 mmHg X min X kg X ml-1. Arterial and venous compliances decreased (P less than 0.01) from 0.08 +/- 0.01 to 0.05 +/- 0.01 ml X mmHg-1 X kg-1 and from 2.1 +/- 0.1 to 1.4 +/- 0.1 ml X mmHg-1 X kg-1, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

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Influence of critical closing pressure on systemic vascular resistance and total arterial compliance: A clinical invasive study

Archives of Cardiovascular Diseases ◽

10.1016/j.acvd.2017.03.008 ◽

2017 ◽

Vol 110 (12) ◽

pp. 659-666 ◽

Cited By ~ 4

Author(s):

Denis Chemla ◽

Edmund M.T. Lau ◽

Philippe Hervé ◽

Sandrine Millasseau ◽

Mabrouk Brahimi ◽

...

Keyword(s):

Systemic Vascular Resistance ◽

Vascular Resistance ◽

Arterial Compliance ◽

Total Arterial Compliance ◽

Critical Closing Pressure ◽

Closing Pressure

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Arterial Stiffness Is Associated With QTc Interval Prolongation in Patients With Heart Failure

Biological Research For Nursing ◽

10.1177/1099800417737835 ◽

2017 ◽

Vol 20 (3) ◽

pp. 255-263

Author(s):

Salah Al-Zaiti ◽

Samir Saba ◽

Rodolfo Pike ◽

Jennifer Williams ◽

Fadi Khraim

Keyword(s):

Heart Failure ◽

Arterial Stiffness ◽

Systemic Vascular Resistance ◽

Vascular Resistance ◽

Arterial Compliance ◽

Qtc Interval ◽

Interval Prolongation ◽

Indirect Measure ◽

Total Arterial Compliance ◽

Qtc Interval Prolongation

Background: A prolonged corrected QT (QTc) interval is a known risk factor for adverse cardiac events. Understanding the determinants and physiologic correlates of QTc is necessary for selecting proper strategies to reduce the risk of adverse events in high-risk patients. We sought to evaluate the role of arterial stiffness in heart failure as a determinant of QTc prolongation. Method: This was an observational study that recruited ambulatory heart failure patients (New York Heart Association Classes I–II) from an outpatient heart failure clinic. In the supine resting position, consented patients underwent noninvasive 12-lead electrocardiograph (ECG) and hemodynamic monitoring using BioZ Dx impedance cardiography. ECGs were evaluated by a reviewer blinded to clinical data, and QTc interval was automatically computed. Patients with pacing or bundle branch block (BBB) were analyzed separately. Strengths of associations were evaluated using Pearson’s r coefficients and multivariate linear regression. Results: The final sample ( N = 44) was 62 ± 13 years of age and 64% male with ejection fraction of 34% ± 12%. At univariate level, QTc interval moderately ( r > .50) correlated with cardiac output, left cardiac work index, systemic vascular resistance, and total arterial compliance in patients with intrinsically narrow QRS complexes. At the multivariate level, increasing systemic vascular resistance and decreasing total arterial compliance remained independent predictors of widening QTc interval in this group ( R2 = .54). No significant correlations were seen in patients with pacing or BBB. Conclusions: In the absence of conduction abnormalities, magnitude of arterial stiffness, an indirect measure of endothelial dysfunction, is associated with QTc interval prolongation.

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