Cardiovascular Response and Control during Exercise<sup>1–</sup><sup>3</sup>

Stone, H. L.; Liang, I. Y. S.

doi:10.1164/arrd.1984.129.2p2.s13

Cited by 19 publications

(11 citation statements)

References 19 publications

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“…The magnitude of the fall in speed pulsatility during each maximal exercise study was highly significant. This is consistent with the known effect of exercise to increase stroke volume in normal subjects (15) and with reports of increased stroke volume with exercise even in patients with left ventricular failure (20). Therefore, the reduction in speed pulsatility index cannot be explained by reduced LV filling at high heart rates.…”

Section: Discussionsupporting

confidence: 91%

“…This is consistent with the known effect of exercise to increase stroke volume in normal subjects (15) and with reports of increased stroke volume with exercise even in patients with left ventricular failure (20). This is consistent with the known effect of exercise to increase stroke volume in normal subjects (15) and with reports of increased stroke volume with exercise even in patients with left ventricular failure (20).…”

Section: Discussionsupporting

confidence: 89%

“…Changes in heart rate seen across the patient group varied widely with some patients failing to develop a significant tachycardia at all. The same cannot be said for increases in heart rate for which there is multiple unrelated underlying causes (15). The difference between pulmonary capillary wedge pressures and mean aortic pressure (pressure gradient across the left ventricle) while bearing only an approximate relation to the actual pressure gradient across the pump was of equal statistical significance.…”

Section: Discussionmentioning

confidence: 97%

“…It could also be argued that increased delivery from the right ventricle underlies the increase in pulmonary capillary wedge pressure (PCWP) accounting mainly for the reduced pressure gradient across the left ventricle. The same cannot be said for increases in heart rate for which there is multiple unrelated underlying causes (15).…”

Section: Discussionmentioning

confidence: 99%

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Exercise Studies in Patients With Rotary Blood Pumps: Cause, Effects, and Implications for Starling‐Like Control of Changes in Pump Flow

Salamonsen¹,

Pellegrino²,

Hayes

et al. 2013

Artificial Organs

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This multicenter study examines in detail the spontaneous increase in pump flow at fixed speed that occurs in exercise. Eight patients implanted with the VentrAssist rotary blood pump were subjected to maximal and submaximal cycle ergometry studies, the latter being completed with patients supine and monitored with right heart catheter and echocardiography. Maximal exercise studies conducted in each patient at three different pump speeds on separate days established initially the magnitude and consistency of increases in pump flow that correlated well with changes in heart rate. However, there was considerable variation, coefficients of variation for mean heart rate and pump flow being 47.9 and 49.3%, respectively. Secondly, these studies indicated that increasing pump flows caused significant improvements in maximal exercise capacity. An increase of 2.1 L/min (35%) in maximum blood flow caused 12 W (16%) further increase in achievable work, 1.26 (9.3%) mL/kg/min in maximal oxygen uptake, and 2.3 (23%) mL/kg/min in anaerobic threshold. Mean increases in lactate were 0.85 mm (24%), but mean B-type natiuretic peptide fell by 126 mm, (-78%). From submaximal supine exercise studies, multiple linear regression of pump flow on factors thought to underlie the spontaneous increase in pump flow indicated that it was associated with increases in heart rate (P = 0.039), pressure gradient across the left ventricle (P = 0.032), and right atrial pressure (P = 0.003). These changes have implications for the recently reported Starling-like controller for pump flow based on pump pulsatility values, which emulates the Starling curve relating pump output to left ventricular preload. Unmodified, the controller would not permit the full benefits of this effect to be afforded to patients implanted with rotary blood pumps. A modification to the pump control algorithm is proposed to eliminate this problem.

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Section: Discussionsupporting

confidence: 91%

Section: Discussionsupporting

confidence: 89%

Section: Discussionmentioning

confidence: 97%

Section: Discussionmentioning

confidence: 99%

See 2 more Smart Citations

Exercise Studies in Patients With Rotary Blood Pumps: Cause, Effects, and Implications for Starling‐Like Control of Changes in Pump Flow

Salamonsen¹,

Pellegrino²,

Hayes

et al. 2013

Artificial Organs

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“…Heart rates were also comparable for all three groups. This suggests that the changes in cardiac output will have been similar [25] in the three groups. Therefore during exercise a higher systemic vascular resistance has been 'unmasked' in the CS-treated patients.…”

Section: Discussionmentioning

confidence: 75%

Hypertensive Exercise Responses in Ciclosporin-Treated Normotensive Renal Transplant Recipients

Scott¹,

Hay²,

Higenbottam³

et al. 1990

Nephron

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Although many patients taking ciclosporin (CS) for the long term develop hypertensive side effects, a proportion do not. We have studied the blood pressure response to graded upright bicycle exercise while continuously recording the metabolic rate in 18 normotensive renal transplant recipients whose mean age was 30.8 years (range 16–54). Nine were treated with CS alone and 9 with azathioprine and a steroid, prednisolone (AzS). Both groups performed a progressive exercise test, with work increasing by 25 W every 4 min from rest. All patients completed a workload of at least 75 W during the test. A group of 8 normal subjects whose mean age was 29 years (range 19–44) were exercised with the same protocol. The CS group had a significantly higher mean systemic blood pressure at both 50 and 75 W (124 and 132 mm Hg, respectively), compared with the AzS group (103 and 108 mm Hg; p < 0.01). The blood pressure response to exercise in the AzS group was similar to that observed in the normal group. This was despite a higher metabolic rate at each stage of work in the AzS group as compared with the CS or normal groups. Despite being normotensive at rest, renal transplant patients who are treated with CS have evidence of a vasopressor effect, with systemic vascular resistance inappropriately high for exercise, implying reduced compliance of the vascular bed.

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Lactate Transport and Exchange During Exercise

Gladden

1996

Comprehensive Physiology

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The sections in this article are: Why Does [La] Increase During Exercise? Muscle Hypoxia: The Traditional Hypothesis Evidence Against Muscle Hypoxia Multiple Factors Criticism of Evidence Against O 2 ‐limitation Near‐Equilibrium Steady State: A Unifying Hypothesis? Summary The Lactate Shuttle Carrier‐Mediated Lactate Transport Lactate Transport in Sarcolemmal Vesicles Lactate Transport in Isolated Cells Reconstitution of the Lactate Carrier Lactate Transport In Situ Summary Muscle as a Consumer of Lactate: Regulating Factors Lactate Concentration Metabolic Rate Blood Flow Hydrogen Ion Concentration Muscle Fiber Type Exercise Training Summary Blood Transport of Lactate Lactate Distribution between Plasma and RBCs Comparative Aspects of Lactate Transport in RBCs Altitude The Lactate Paradox Explanations for the Lactate Paradox Summary

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Cardiovascular Response and Control during Exercise^1–³

Cited by 19 publications

References 19 publications

Exercise Studies in Patients With Rotary Blood Pumps: Cause, Effects, and Implications for Starling‐Like Control of Changes in Pump Flow

Exercise Studies in Patients With Rotary Blood Pumps: Cause, Effects, and Implications for Starling‐Like Control of Changes in Pump Flow

Hypertensive Exercise Responses in Ciclosporin-Treated Normotensive Renal Transplant Recipients

Lactate Transport and Exchange During Exercise

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Cardiovascular Response and Control during Exercise1–3

Cited by 19 publications

References 19 publications

Exercise Studies in Patients With Rotary Blood Pumps: Cause, Effects, and Implications for Starling‐Like Control of Changes in Pump Flow

Exercise Studies in Patients With Rotary Blood Pumps: Cause, Effects, and Implications for Starling‐Like Control of Changes in Pump Flow

Hypertensive Exercise Responses in Ciclosporin-Treated Normotensive Renal Transplant Recipients

Lactate Transport and Exchange During Exercise

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Cardiovascular Response and Control during Exercise^1–³