Intramyocardial pressure in the canine heart and its relationship to coronary blood flow. by Frederick William Heineman

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Pagination232 leaves.
Number of Pages232
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Open LibraryOL14731214M

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Pressure and stress. Here, significant differences are well established. Robicsek and Thubrikar measured the intramyocardial pressure at different levels of the myocardium in a canine a modified version of the law of Laplace, they demonstrated that the intramyocardial coronary arteries undergo significantly lower levels of mural stress, in both the linear dimension (shear stress Cited by: 3.

J Thorac Cardiovasc Surg. Oct;64(4) Intramyocardial pressure. The persistence of its transmural gradient in the empty heart and its relationship to myocardial oxygen by: Coronary heart disease is one of the major health problems in indus trialized nations because of its high incidence and severity.

Recent innovations in medical and surgical treatment of coronary heart dis ease have increased the importance of accurate diagnostic methods for determining the severity of coronary disease, identifying potential treatment alternatives, and evaluating the results of. KEY WORDS intramyocardial pressure pressure-flow relationship maximal dilation dogs extravascular resistance blood flow model • Systole impedes the rate of coronary inflow (1), but the mechanism whereby contraction interacts with blood flow has yet to be defined.

In a previous study we have suggested that intramyocardial pressures reduce. Intramyocardial pressure. A study of its regional variations and its relationship to intraventricular pressure.

Baird RJ, Manktelow RT, Shah PA, Ameli FM. PMID: [PubMed - indexed for MEDLINE] MeSH Terms. Animals; Aorta; Blood Flow Velocity; Blood Pressure* Blood Pressure Determination; Coronary Vessels* Dogs; Endocardium; Heart Cited by: The heart is uniquely responsible for providing its own blood supply through the coronary circulation.

Regulation of coronary blood flow is quite complex and, after over years of dedicated. Since coronary blood flow is primarily diastolic and subendocardial flow is totally so, consideration of the diastolic pressure gradient - and hence diastolic intramyocardial pressure - is important.

We found that preload had no meaningful effect on diastolic coronary flow during maximal vasodilation (Rmin) at aortic root pressures of 70 to Abstract. Two phenomena determine the heart’s resistance to coronary blood flow — the caliber of the resistance vessels as determined by smooth muscle in the walls of the coronary vessels and deformation of those vessels by the mechanical motion of the beating heart.

In a state of steady maximal hyperemia, as can be achieved with adenosine, coronary autoregulation is abolished, and coronary blood flow is directly proportional to blood pressure.

This principle has been used to substitute the measurements of flow by the more simple and reproducible measurements of pressure[ 32 ]. 4) The current flow was often disproportionate to the voltage gradient between and minutes after occlusion, possibly indicating electrical uncoupling of the infarcting cells from normal cells.

These data indicate that intramyocardial current flow develops early after acute coronary occlusion. Blood pressure,stroke and coronary heart disease. Part 1. Prolonged differences in blood pressure: prospective observational studies corrected for.

Pressure work of the heart has long been known to be more costly in terms of myocardial oxygen consumption and coronary blood flow than an apparently equivalent volume work.

This problem was restudied in the dog. Pressure work and volume work were shown to be equivalent when the analysis was carried out from the point of view that the heart.

We have observed that hydrogen peroxide (H2O2), the dismutated product of superoxide, is a coronary metabolic dilator and couples myocardial oxygen consumption to coronary blood flow. Baird, R.J., Goldbach, M.M., and de la Rocha, A.Intramyocardial pressure: the persistence of its transmural gradient in the empty heart and its relationship to myocardial oxygen consumption.

J Thorac Cardiovasc Surg – We analysed the relationship between artery pressure (AP) and coronary flow (F) in the canine coronary bed, using an electrical analog model of the coronary circulation.

The model contained a capacitance of epicardial vessels, input and terminal resistances, diode, and the number of e.m.f., simulated the intramyocardial pressure and zero-flow.

Baird RJ, Manktelow RT, Shah PA, Ameli FM: Intramyocardial pressure. The persistence of its transmural gradient in the empty heart and its relationship to myocardial oxygen consumption.

J Thoracic and Cardiovasc Surg ;– Google Scholar. Intramyocardial pressure was considered to arise via contraction-related myocyte thickening and transmission of ventricular cavity pressure into the heart wall.

1D network geometry from published. The topic of the J-curve relationship between blood pressure and coronary artery disease (CAD) has been the subject of much controversy for the past decades. An inverse relationship between diastolic pressure and adverse cardiac ischemic events (i.e., the lower the diastolic pressure the greater the risk of coronary heart disease and adverse outcomes) has been observed in numerous studies.

Blood flow in coronary vessels is governed by the principles of fluid dynamics, namely: the flow is the result of the pressure gradient across the vascular bed divided by the resistance.

Aortic root pressure minus right atrial pressure or left ventricular diastolic pressure defines the pressure gradient or perfusion pressure.

Summary. The hemodynamic properties of the coronary circulation are generally defined by coronary arterial pressure—flow relations. Under normal physiological conditions, such a relationship demonstrates the ability of the coronary system to keep coronary flow at a rather constant level depending on oxygen consumption.

cise physical meaning of the coronary pressure-flow relationship are still unsettled issues. Two recent studies indicate that the coronary ar-terial pressure-flow relationship is often curved (Klocke et al., ; Messina et al., ), and an-other study shows that a straight relationship may be obtained even when coronary resistance is known.

The peripheral coronary circulation was modeled by an intramyocardial pump model. An innovative feature introduced in CCM is a physiological model between the coronary circulation and the end systolic pressure volume relationship function of the ventricles. CCM was integrated with the whole, closed-loop model of the cardiovascular system.

Carotid Artery Diseases Renal Artery Obstruction Carotid Artery Injuries Arterial Occlusive Diseases Coronary Disease Infarction, Middle Cerebral Artery Retinal Artery Occlusion Carotid Artery Thrombosis Aneurysm Carotid Stenosis Carotid Artery, Internal, Dissection Constriction, Pathologic Coronary Stenosis Myocardial Infarction Vertebral.

Paradoxically the heart, which is solely dedicated to supplying blood to the organs, restricts its own blood supply during peak contraction (fig 1).

To overcome this restriction, the heart has numerous mechanisms which delicately balance the blood flow demands of the systemic and coronary circulation. Figure 1 Striking difference in the flow velocity waveform between the proximal aorta (A) and.

Objective: To investigate the underlying mechanisms of a decreased coronary flow reserve after myocardial infarction (MI) by analysing the characteristics of the diastolic hyperaemic coronary pressure–flow relationship. Design: Prospective study. Setting: Tertiary care hospital.

Patients: 68 patients with a recent MI and 27 patients with stable angina pectoris (AP; control group). The current study was designed to utilize cardiac micro–computed tomography (micro-CT) technology as a novel imaging strategy, to define the 3-dimensional coronary circulation in the young and aged heart and its relationship to LV fibrosis and function.

Heart rate is the most important determinant of MVO heart rate doubles, myocardial oxygen uptake approximately doubles.

Heart rate is a dominant factor in the O2 supply-demand ratio for two reasons: Increases in heart rate also increase oxygen consumption, and increases in heart rate reduce subendocardial coronary flow owing to shortening of the diastolic filling period.

Relationship between changes in bipolar electrograms and regional myocardial blood flow during acute coronary artery occlusion in the dog. Circ Res. ; Crossref Medline Google Scholar; 47 Mirvis DM, Ramanathan KB, Wilson JL. Regional blood flow correlates of ST-segment depression in tachycardia-induced myocardial ischemia.

Background Changes in intramyocardial blood volume (IBV) mediate autoregulatory adaptations to coronary stenosis. This study investigated whether (1) myocardial contrast echocardiography (MCE) can quantify changes in IBV during coronary stenosis and (2) the relation between coronary resistance– and MCE-derived IBV could yield insight into structural mechanisms of IBV change.

Despite the fact that coronary blood flow was held constant at a relatively normal value of 95 d m i n. gm of tissue, there was coronary vasodilatation evidenced by a fall in perfusion pressure from mm Hg to 78 mm Hg. point, flow distribution in the myocardium is subject principally to mechanical forces such as myocardial wall tensions.

Intramyocardial pressure: effect of preload on transmural distribution of systolic coronary blood flow. Am J Cardiol. ; – doi: /(75) Crossref Medline Google Scholar; Giezeman MJ, VanBavel E, Grimbergen CA, Spaan JA.

Compliance of isolated porcine coronary small arteries and coronary pressure-flow. In our concept of the interaction between intramyocardial pressure (IMP) and myocardial perfusion, IMP is defined as the hydrostatic pressure in the soft tissue surrounding the myocardial fibers. the modulations of coronary artery flow were found to be similar to those found in animal experiments in open-chest dogs.

Issue Section: Research. (Mean values SE.) In Group 2 dogs, mean aortic pressure was 95 mm Hg before bypass and 42 ' mm Hg during the first 30 minutes of perfusion (see the Table; Fig.

After initiation of bypass, circumflex coronary artery blood flow decreased from 31 to 18 mumin. ΔP is the driving pressure gradient between the origin of the coronary vasculature in the aortic root and its orifice, that is, of the coronary sinus into the right atrium. Now the coronary vasculature has one particular and unique property: it is being compressed by the contracting myocardium throughout systole, such that the pipe is—at least functionally—obstructed and no flow occurs.

Coronary circulation is the circulation of blood in the blood vessels that supply the heart muscle (myocardium). Coronary arteries supply oxygenated blood to the heart muscle, and cardiac veins drain away the blood once it has been deoxygenated.

Because the rest of the body, and most especially the brain, needs a steady supply of oxygenated blood that is free of all but the slightest. Hiroyuki Suga's research works with 4, citations and 1, reads, including: Energy Costs of PVA and Emax: Constancy and Variability. Objectives: To compare the relationship between dobutamine myocardial blood flow (MBF), rate–pressure product (RPP) and stenosis severity in patients with coronary artery disease (CAD).

Methods: 27 patients with single-vessel CAD were allocated to three groups based on stenosis severity: group 1, 50–69% (n = 9); group 2, 70–89% (n = 9); and group 3, ⩾ 90% (n = 9).

Nine normal. Coronary Circulation The coronary vasculature supplies blood to the muscles of the heart (myocardium). These coronary arteries are the first branches (right & left coronary arteries) that arise from the aorta, and they run on the surface of the heart’s muscle.

Branches from the arteries penetrate the muscle in order to supply blood to deeper [ ]. The relationship between blood volume, blood pressure, and blood flow is intuitively obvious.

Water may merely trickle along a creek bed in a dry season, but rush quickly and under great pressure after a heavy rain. Similarly, as blood volume decreases, pressure and flow decrease. As blood volume increases, pressure and flow increase.

The coronary microcirculation is a dynamic vascular bed that responds through changes in arteriolar resistance to metabolic tissue demands, changes in blood flow, and neurohormonal stimuli. Also Visit Click here for information on Cardiovascular Physiology Concepts, 2nd edition, a textbook published by Lippincott Williams & Wilkins ().

Click here for information on Normal and Abnormal Blood Pressure, a textbook published by Richard E. Klabunde ().change in coronary flow imposed was an abrupt large change instead of stepwise smaller ones, this might influence the result.

Four experiments of this type were done in three preparations. Aortic pressure, stroke volume, and heart rate were held constant. In these four experiments, coronary blood flow was changed from toto the phasic nature of coronary blood flow (CBF) is attributable to unique interactions between the continuously beating heart and coronary vessels, especially during ventricular systole when coronary flow is impeded and often transiently reversed (2, 24).This systolic reduction and reversal of flow, the coronary systolic flow impediment, results from the compressive effect of cardiac.

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