Physiological hypotheses-Intramyocardial pressure. A new concept, suggestions for measurement

Westerhof, Nicolaas

doi:10.1007/bf01906964

Cited by 56 publications

(35 citation statements)

References 67 publications

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“…In general, the reported results are somewhat inconsistent and appear to depend on measurement technique. As Westerhof (22) summarizes, some authors have found subendocardial IMP higher than VP, whereas others have found IMP to be lower than peak systolic VP (5). Most groups, however, agree that IMP decreases relatively smoothly from endocardium to epicardium, as suggested by some theoretical models (22).…”

Section: Discussionmentioning

confidence: 99%

“…As Westerhof (22) summarizes, some authors have found subendocardial IMP higher than VP, whereas others have found IMP to be lower than peak systolic VP (5). Most groups, however, agree that IMP decreases relatively smoothly from endocardium to epicardium, as suggested by some theoretical models (22). This distribution may be related to the greater stress and strain predicted by models for the subendocardial layers (26).…”

Section: Discussionmentioning

confidence: 99%

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Intramyocardial pressure measurements in the stage 18 embryonic chick heart

Chabert

Taber

2002

American Journal of Physiology-Heart and Circulatory Physiology

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/ajpheart.00364. 2001.-Intramyocardial pressure (IMP) and ventricular pressure (VP) were measured in the trabeculating heart of the stage 18 chick embryo (3 days of incubation). Pressure was measured at several locations across the ventricle using a fluid-filled servo-null system. Maximum systolic and minimum diastolic IMP tended to be greater in the dorsal wall than in the ventral wall, but transmural distributions of peak active (maximum minus minimum) IMP were similar in both walls. Peak active IMP near midwall was similar to peak active VP, but peak active IMP in the subepicardial and subendocardial layers was four to five times larger. These results suggest that the passive stiffness of the dorsal wall is greater than that of the ventral wall and that during contraction the inner and outer layers of both walls generate more contractile force and/or become less permeable to flow than the middle part of the wall. Measured pressures likely correspond to regional variations in wall stress that may influence morphogenesis and function in the embryonic heart. heart development; cardiac mechanics; chick embryo MECHANICAL FORCES affect form and function in the developing embryonic heart. Although this fact has been recognized for a long time, the nature and magnitude of these forces remain largely unexplored. One of these forces, blood pressure, has been measured in chick (3,6,9,11,14,21) and zebrafish (7) embryos, but it is the ventricular wall stress due to this pressure that likely controls, in part, the processes of growth, remodeling, and morphogenesis (20).Both solid and fluid components of the heart wall are subjected to stress. Currently, there is no direct way to reliably measure the stress in the solid part of the wall (8), and so, theoretical models are used to estimate solid stress (12,25,26). Intramyocardial pressure (IMP) in the fluid compartments, however, can be measured using a micropressure transducer. Although somewhat inconsistent, published measurements of IMP in the mature heart have yielded considerable insight into the mechanical behavior of the heart wall and have shown that IMP is affected by ventricular pressure (VP), perfusion pressure, and muscle contractility (5,13,15,18,23,27).The purpose of the present study was to measure IMP in the ventricle of the beating, stage 18 embryonic chick heart. This stage of development (3 days of incubation) coincides with the onset of myocardial trabeculation, a critical morphogenetic process (17). Results indicate that IMP varies regionally. In general, maximum systolic and minimum diastolic IMP were greater in the dorsal wall than in the ventral wall, but the peak active (maximum minus minimum) IMP distributions were similar in both walls. Peak active IMP at midwall was similar to peak active VP, but peak active IMP in the subepicardial and subendocardial wall layers was four to five times larger. We speculate that such regional variations in IMP may play a role in the growth and remodeling of trabeculae and may reflect material heterogeneity of the ...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Intramyocardial pressure measurements in the stage 18 embryonic chick heart

Chabert

Taber

2002

American Journal of Physiology-Heart and Circulatory Physiology

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“…A minimal model should contain a representation of the relationships between inflow pressures, ventricular pressures and outflow pressures. An example is the cyclical elastance model of the heart [2], a remarkably simple model adequate to give reasonable approximations to the pressure waveforms in the ventricle and aorta, and reasonable stroke volumes, and even reasonable durations of transients in response to changes in state.…”

Section: Models Of the Cardionomementioning

confidence: 99%

Toward Modeling the Human Physionome

Bassingthwaighte

1995

Advances in Experimental Medicine and Biology

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The physionome is the description of the physiological dynamics of the normal intact organism. The march of science brings us now into the era where integration of the various facets of the knowledge of biology and medicine has become a major issue. Modeling is a vehicle for the combining of information from molecular biology, biophysics, and medical biology, but must be combined with strategies for databasing the raw data with greater efficiency than is currently possible. The lessons from the genome project can be applied to the next level major projects, the morphonome and the physionome, the objective being to put integrated forms of the data into the hands of physicians and medical scientists.

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“…In the venous compartment no valves are present, thus an increase in developed venous pressure leads instantaneously to a decrease in venous volume. However, if the end-diastolic volume increases, as indicated by the arrow along the diastolic pressure-volume curve (for instance by prolongation of diastole), systolic venous pressure will be increased in the following systole, depending on the amount of volume displaced, irrespective of the developed left ventricular pressure (figure modified from Westerhof, 1990). A change in inotropic state of the ventricle will affect the venous pressure pulse by changing the slope of the end-systolic elastance relation.…”

Section: Statistical Testsmentioning

confidence: 99%

“…An alternative hypothesis to explain pressure generation in intramyocardial vessels put forward by Krams et al (1989) and Westerhof (1990) predicts that the pressure in the intramyocardial vessels depends on cyclical elastance variations and vascular volume (see Introduction). As is illustrated in Fig.…”

Section: Generation Of Pressure Pulses In Intramyocardial Veinsmentioning

confidence: 99%

Cardiac contraction and intramyocardial venous pressure generation in the anaesthetized dog.

Vergroesen

Han

Goto

et al. 1994

The Journal of Physiology

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1. Two hypotheses relating to the influence of contraction of the heart on coronary venous pressure (Pv) were tested. The first assumes a direct transmission of left ventricular pressure (PLv). According Progress in understanding the mechanics of the coronary circulation has been hampered by a lack of insight into the events that take place in the intramyocardial small vessels. Recent studies indicate that intramyocardial vascular blood volumes vary during the heart cycle in a fashion that is related to the resistance of the microvessels (Hoffman & Spaan, 1990). Moreover, volume variations are related to the capacitive flow components that contribute to the phasic behaviour of coronary arterial and venous flow (Spaan, Bruinsma & Laird, 1983). In order to gain a better understanding of the factors that control the mechanism of blood flow into and out of the intramyocardial vessels it is important that we identify the forces that are exerted by contraction of the heart on the vessels and how these are modified by vascular tone. In the past it was widely accepted that contraction forces were related to tissue pressure, which in turn was directly determined by the pressures generated within the left ventricular cavity (Downey & Kirk, 1975). This hypothesis assumes a direct transmission of left ventricular pressure, one to one at the subendocardium and decreasing to zero at the subepicardium. If this hypothesis is correct then in an epicardial vein, cannulated retrogradely, the pressure pulse should essentially equal 0 5 times the left ventricular pressure pulse. Contradicting this hypothesis, Krams, Sipkema & Westerhof (1989) showed that in the isolated cat heart changes in the elastance of the myocardium between systole and diastole could be a major factor determining systolic to diastolic flow differences in the coronary arteries. According to this alternative hypothesis the magnitude of the pressure pulse in any compartment inside the heart muscle would then be determined by the volume of this compartment and by the maximal systolic elastance of the heart muscle. Krams et al. (1989) found no direct transmission of the left ventricular pressure pulse on the flow pulsations. However, the coronary vessels may not be simply affected by either elastance or left ventricular pressure. Kouwenhoven, Vergroesen, Han & Spaan (1992) showed in a recent study that left ventricular pressure can affect considerably coronary arterial pressure and early systolic flow, depending on the mode of perfusion of the coronary circulation. The two modes of perfusion can be denoted as pressure clamping or constant M$S 1860, pp. 343-353 343

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Physiological hypotheses-Intramyocardial pressure. A new concept, suggestions for measurement

Cited by 56 publications

References 67 publications

Intramyocardial pressure measurements in the stage 18 embryonic chick heart

Intramyocardial pressure measurements in the stage 18 embryonic chick heart

Toward Modeling the Human Physionome

Cardiac contraction and intramyocardial venous pressure generation in the anaesthetized dog.

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