Left ventricular circumference changes in right heart bypassed preparations

He, Chao; Taylor, RR; Rh, McDonald; Jp, Gilmore

doi:10.1152/ajplegacy.1966.211.3.681

Cited by 10 publications

(4 citation statements)

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“…For example, assuming the ventricle to be spherical, if the muscle fibers were arranged entirely at random and developing equal force, then mean wall tension would underestimate the tension actually developed by individual fibers by a factor of two. During the isovolumic phase of auxotonic contractions there is shortening of the left ventricular base-to-apex length with an increase in circumferential dimensions (30,31) that tends to produce a more spherical configuration, although much of the increase in external circumference can be accounted for by the approximately 10% increase in wall thickness (32). The magnitude of shape changes, as reflected in the external circumference, varies directly with the pressure developed during the isovolumic phase of contraction (31), and in fully isovolumic contractions, the external circumference increases progressively until peak pressure is reached (33).…”

Section: Taylor Ross Covell Sonnenblickmentioning

confidence: 99%

“…During the isovolumic phase of auxotonic contractions there is shortening of the left ventricular base-to-apex length with an increase in circumferential dimensions (30,31) that tends to produce a more spherical configuration, although much of the increase in external circumference can be accounted for by the approximately 10% increase in wall thickness (32). The magnitude of shape changes, as reflected in the external circumference, varies directly with the pressure developed during the isovolumic phase of contraction (31), and in fully isovolumic contractions, the external circumference increases progressively until peak pressure is reached (33). The relative error involved in mean tension estimation by assuming the ventricle to be spherical rather than a prolate spheroid of equal volume with a major-minor axis of 2:1 is approximately 8% (34).…”

Section: Taylor Ross Covell Sonnenblickmentioning

confidence: 99%

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A Quantitative Analysis of Left Ventricular Myocardial Function in the Intact, Sedated Dog

Taylor

Ross

Covell

et al. 1967

Circulation Research

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Instantaneous contractile element velocity was calculated from left ventricular pressure and its first derivative during isovolumic left ventricular contractions produced by sudden balloon occlusion of the ascending aorta during diastole in closed-chest, sedated dogs. Wall tension was derived from ventricular pressure and volume, the latter being obtained from the pressure-volume relation of the arrested ventricle. During isovolumic contractions, there was an inverse curvilinear relation between tension and velocity, except at the onset of contraction and near peak tension. Increasing diastolic ventricular volume shifted the tension-velocity relations to the right, with increase in mean total isovolumic tension from 188 to 471 g/cm 2 , but without an obvious change in extrapolation to maximum velocity, which averaged 3.0 circumferences/sec. End-diastolic pressure-tension and circumference-tension relations indicated that active tension development continued to increase up to the maximum measured enddiastolic pressures of approximately 20 mm Hg. The normalized data, pooled from 15 animals, showed little scatter in the data for tension and velocity. It is concluded that the contractile properties of left ventricular muscle in the intact, sedated dog may be meaningfully described by tension-velocity relations obtained from single isovolumic contractions. The responses of the intact ventricle to increased diastolic volume and digitalis glycosides are analogous to those of isolated cardiac muscle. The small variability in the normalized tension-velocity relations in the normal dog suggests that it will also be possible to characterize abnormal left ventricular function with this approach.ADDITIONAL KEY WORDS mechanics of cardiac muscle ventricular filling left ventricular ejected fraction force-velocity relations left ventricular tension digitalis glycosides• Cardiac function in the intact animal and man is ordinarily assessed in hemodynamic terms which reflect not only the function of the heart but also the body's metabolic demands and the state of the peripheral circulation. The relations between cardiac filling pressure and the stroke volume, stroke work, or stroke power, which are of considerable value in assessing cardiac function in

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Section: Taylor Ross Covell Sonnenblickmentioning

confidence: 99%

Section: Taylor Ross Covell Sonnenblickmentioning

confidence: 99%

A Quantitative Analysis of Left Ventricular Myocardial Function in the Intact, Sedated Dog

Taylor

Ross

Covell

et al. 1967

Circulation Research

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“…Attempts have been made to study myocardial mechanics in vivo by means of indicator dilution technique (1 6, 21, 23), angiocardiography in dog and man with and without epicardial markers (12,18,19,27), and by distance transducers sewn into the myocardium (1,7,8,13,15,22). Most available information concerning myocardial mechanics has been obtained on isolated preparations of papillary muscle, which do not contract spontaneously, and have a specialized function.…”

mentioning

confidence: 99%

Relationship Between Local Myocardial Dimensions and Left Ventricular Volume in Dogs

Lekven

Bugge-Asperheim

Kiil

1972

Scandinavian Journal of Clinical and Laboratory Investigation

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Ultrasonic elements inserted parallel to the surface of the anterior wall of the left ventricle in open-chest dogs were used to determine myocardial distances (MCL). During saline loading with and without administration of isoproterenol, end-systolic and end-diastolic MCL were compared with the corresponding ventricular volumes (ESV and EDV), estimated by thermodilution technique. In individual experiments, correlation coefficients for the relationship between MCL3 and ventricular volumes ranged from 0.91 to 0.99. It is concluded that stroke volume can be analyzed in terms of endsystolic and end-diastolic MCL, and that the thermodilution technique correctly determines ESV/EDV.

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“…The first derivative of left ventricular pressure development (dp/dt) was obtained by electronic differentiation. External left ventricular circumference segment length was determined with mereury-inrubber gauges sutured to the wall of the left ventricle, as described previously (14). Positivepressure ventilation was maintained by a Harvard pump.…”

Section: Heart-lung Preparationmentioning

confidence: 99%

Mechanism of Action of Tris (Hydroxymethyl) Aminomethane on the Negative Inotropic Effect of Carbon Dioxide

González¹,

Cingolani²,

Mattiazzi³

et al. 1971

Circulation Research

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Administration of isotonic THAM to the blood of the heart-lung preparation induced a decrease in the negative inotropic effect of CO 2 , suggested by the fact that, at constant stroke work, an increase in Pco 2 of 26 ± 1.9 mm Hg was followed by an increase in left ventricular end-diastolic pressure (LVEDP) of 3.8 ± 0.2 mm Hg before the infusion of THAM; after THAM was given, a similar increase in Pco 2 induced an increase in LVEDP of 1.8 ± 0.2 mm Hg (P<0.01). When pH was increased by 0.15M NaHCO 3 , no changes in myocardial contractility or in the tolerance of the heart to CO 2 were found. On the other hand, hemodilution with isotonic sucrose reproduced the effect of THAM. Either sucrose or THAM produced a decrease in plasma Na. Myocardial contractility, previously increased by THAM or sucrose, returned to control after plasma Na was restored. When cat papillary muscles were immersed in Ringer's solution with normal (142 mn) and low (112 msi) Na concentration, it was observed that a similar increase in Pco 2 originated a smaller decrease in contractility when the muscles were in the low Na solution. It is concluded that the effect of THAM in the present experiments is due, at least to an important extent, to changes in extracellular Na.KEY WORDS myocardial contractility cat papillary muscle dog heart-lung preparation low extracellular [Na] extracellular pH hemodilution osmolarity• Tris (hydroxymethyl) aminomethane (THAM) is an amine buffer that was introduced in 1960 (1) in the clinical treatment of acid base disorders. Its use has been stimulated by the observation that it apparently buffers the intracellular as well as the extracellular space (2, 3).The cardiovascular actions of THAM have been extensively studied (4-12). It has been shown that the infusion of THAM in acidotic dogs increases myocardial contractile force (4-9) and that the replacement of NaHCO 3 by This study was supported in part by a grant from the Comision de Investigacion Cientifica, Universidad National de La Plata, Argentina.From the Institute de Fisiologia, Facultad de Ciencias Medicas, La Plata, Argentina.Dr. Gonzalez' present address is Department of Physiology, University of Kansas Medical Center, Kansas City, Kansas 66103.Received July 8, 1970. Accepted for publication November 5, 1970. THAM is associated with an increase in the developed tension of the isolated atrium (11). However, when THAM titrated to pH 7.4 is injected into the coronary circulation, no changes in myocardial contractile force are produced (9). In preliminary experiments from this laboratory (13) we observed that the administration of 0.3M THAM solution increased myocardial contractility in the isolated heart-lung preparation. On the other hand, the in vitro replacement of NaHCO.s by THAM was followed by an increase in contractility of cat papillary muscles only when a significant decrease in Na concentration of the medium was achieved (12).To supply further information about the effect of THAM upon myocardial contractility and the mechanism of its actio...

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Left ventricular circumference changes in right heart bypassed preparations

Cited by 10 publications

References 0 publications

A Quantitative Analysis of Left Ventricular Myocardial Function in the Intact, Sedated Dog

A Quantitative Analysis of Left Ventricular Myocardial Function in the Intact, Sedated Dog

Relationship Between Local Myocardial Dimensions and Left Ventricular Volume in Dogs

Mechanism of Action of Tris (Hydroxymethyl) Aminomethane on the Negative Inotropic Effect of Carbon Dioxide

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