Preload-induced alterations in capacitance-free diastolic pressure-flow relationship

Aversano, Thomas; Klocke, Francis J.; Mates, Robert E.; Canty, John M.

doi:10.1152/ajpheart.1984.246.3.h410

Cited by 37 publications

(33 citation statements)

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“…LVEDP tended to be lower after sildenafil; a decrease in diastolic intracavitary pressure would reduce extravascular forces that impede blood flow in the microcirculation. 18 In contrast, a trend existed toward increased heart rate after sildenafil; increase in heart rate would increase extravascular forces opposing coronary blood flow and might cause a decrease in myocardial perfusion. 19 However, neither the change in LVEDP nor the change in heart rate were significant.…”

Section: Pde5 Inhibition During Exercise With Myocardial Ischemiamentioning

confidence: 98%

Cyclic Nucleotide Phosphodiesterase Type 5 Activity Limits Blood Flow to Hypoperfused Myocardium During Exercise

Traverse

Chen

et al. 2000

Circulation

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Background-Nitric oxide (NO) causes vasodilation by stimulation of guanylate cyclase in vascular smooth muscle to produce cGMP. The resultant vasodilator effect is regulated by a family of cGMP phosphodiesterases (PDEs). Sildenafil, a selective inhibitor of PDE5 used for treatment of erectile dysfunction, has been found to cause relaxation of isolated epicardial coronary artery segments. The present study examined the effects of sildenafil on coronary blood flow and hemodynamics during exercise in normal and ischemic heart. Methods and Results-In chronically instrumented normal dogs, sildenafil 2 mg/kg PO caused a slight but significant increase in left anterior descending (LAD) coronary blood flow during resting conditions, with a nonsignificant trend toward increased coronary flow during treadmill exercise. Exercise in the presence of LAD stenosis that decreased distal coronary pressure to 57Ϯ2 mm Hg reduced LAD flow during exercise from 69Ϯ8 to 41Ϯ7 mL/min (PϽ0.05), with hypoperfusion most severe in the subendocardium. At the same distal coronary pressure, sildenafil increased LAD flow in the ischemic region to 50Ϯ11 mL/min (PϽ0.05). Increase in ischemic region blood flow produced by sildenafil was uniform across the LV wall, given that no change occurred in the transmural distribution of perfusion. Conclusions-Inhibition of PDE5 with sildenafil caused vasodilation of coronary resistance vessels with an increase of blood flow into an ischemic myocardial region during exercise in the presence of coronary artery stenosis. (Circulation.

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Section: Pde5 Inhibition During Exercise With Myocardial Ischemiamentioning

confidence: 98%

Cyclic Nucleotide Phosphodiesterase Type 5 Activity Limits Blood Flow to Hypoperfused Myocardium During Exercise

Traverse

Chen

et al. 2000

Circulation

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“…Finally, inner wall flow can be further limited if intraventricular diastolic pressure is elevated. 9 Although these effects are normally counterbalanced by autoregulatory adjustments in transmural microvascular tone, they are unopposed when the coronary bed is maximally vasodilated. The resulting transmural gradients in flow are usually modest in normally perfused areas, as reflected in the present study by minimal transmural flow gradients in normally perfused myocardium (Figure 7).…”

Section: Lee Et Al Mri Vs Radionuclide Perfusion Imagingmentioning

confidence: 99%

Magnetic Resonance Versus Radionuclide Pharmacological Stress Perfusion Imaging for Flow-Limiting Stenoses of Varying Severity

et al. 2004

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Background-Although magnetic resonance first-pass imaging (MRFP) has potential advantages in pharmacological stress perfusion imaging, direct comparisons of current MRFP and established radionuclide techniques are not available. Methods and Results-Graded regional differences in coronary flow were produced during global coronary vasodilation in chronically instrumented dogs by partially occluding the left circumflex artery. Regional differences in full-thickness flow quantified using microspheres were compared with regional differences obtained with MRFP and radionuclide SPECT imaging ( 99m Tc-sestamibi and 201 Tl). Relative regional flows (RRFs) derived from the initial areas under MRFP signal intensity-time curves were linearly related to reference microsphere RRFs over the full range of vasodilation (yϭ0.93xϩ4.3; r 2 ϭ0.77). Relationships between 99m Tc-sestamibi and 201 Tl RRFs and microsphere RRFs were curvilinear, plateauing as flows increased. The high spatial resolution of the MRI enabled transmural flow to be evaluated in 3 to 5 layers across the myocardial wall. Reductions in subendocardial flow were visually apparent in MRFP images for Ն50% reductions in full-thickness flow. Endocardial-to-epicardial gradients in MRFP flow increased progressively with stenosis severity, whereas transmural flow patterns in remote normally perfused myocardium remained normal. Flow reductions of Ն50% not identified by radionuclide imaging were apparent in MRFP full-thickness and transmural analyses.

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“…There is no doubt that ischemia would have occurred at low flows in the beating heart, but even then it could not explain our results. Although global ischemia could influence flow in the circumflex vascular bed by raising left ventricular end-diastolic pressure, the effect of such increased preload is to raise, not lower, the pressure axis intercepts (Aversano et al, 1984).…”

Section: Effects Of Interarterial Pressure Gradientsmentioning

confidence: 99%

Effects of pressure gradients between branches of the left coronary artery on the pressure axis intercept and the shape of steady state circumflex pressure-flow relations in dogs.

Messina¹,

Hanley²,

Uhlig³

et al. 1985

Circulation Research

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SUMMARY. When steady state pressure-flow relations are studied in the circumflex coronary artery, pressure gradients develop between it and other branches of the left coronary artery. To assess the effects of these pressure gradients, we compared the pressure axis intercept and shape of steady state circumflex pressure-flow relations in the presence and absence of gradients after autoregulation was abolished, both in the beating heart and during long diastoles in dogs. We used peripheral coronary pressures and radionuclide-labeled microspheres to assess arterial collateral flow. In the beating heart, interarterial pressure gradients reduced the curvature at low circumflex pressures, and overestimated the mean pressure axis intercept by 7.8 mm Hg (P < 0.05). The results were similar for the pressure-flow relations derived during long diastoles. This overesrimation exaggerates the difference between the pressure axis intercept and coronary sinus pressure. The peripheral coronary pressure and microsphere results indicate that these effects are mediated largely by arterial collateral flow. {Circ Res 56: 11-19, 1985) CORONARY arterial pressure-flow relations have been used to investigate the physical forces that regulate coronary blood flow (Cross et al., 1961;Downey and Kirk, 1975;Bellamy, 1978). The pressure axis intercept of these relations has been interpreted as the downstream pressure opposing forward flow in the coronary circulation; however, this pressure has greatly exceeded the coronary sinus pressure, which traditionally has been assumed to be the downstream pressure. The shape of these relations, found to be linear by some (Dole and Bishop, 1982;Eng et al., 1982) but curvilinear by others (L'Abbate et al., 1980;Klocke et al., 1981), is thought to convey information about the conductance of the coronary circulation. Because of this variability of the pressure axis intercept and the shape of coronary arterial pressure-flow relations, the physiological significance of both remains uncertain.One factor that might account for this variability is the specific coronary artery in which the pressureflow relation is obtained. In our laboratory, we have consistently found that the pressure axis intercept of a steady state circumflex pressure-flow relation (Verrier et al., 1980;Vlahakes et al., 1982) is much higher than that in a steady state left main coronary arterial pressure-flow relation (Rouleau et al., 1979;Uhlig et al., 1984). A possible explanation for the higher pressure axis intercept of the circumflex pressure-flow relation may be that when circumflex pressure is selectively lowered below that in the other branches of the left coronary artery, interarterial pressure gradients occur and are accompanied by collateral flow that is not measured by the upstream flow transducer. This error in measurement could underestimate total circumflex flow and thus overestimate the pressure axis intercept. Whether these pressure gradients also affect the shape of a circumflex pressure-flow relation is unknown.To assess...

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Preload-induced alterations in capacitance-free diastolic pressure-flow relationship

Cited by 37 publications

References 0 publications

Cyclic Nucleotide Phosphodiesterase Type 5 Activity Limits Blood Flow to Hypoperfused Myocardium During Exercise

Cyclic Nucleotide Phosphodiesterase Type 5 Activity Limits Blood Flow to Hypoperfused Myocardium During Exercise

Magnetic Resonance Versus Radionuclide Pharmacological Stress Perfusion Imaging for Flow-Limiting Stenoses of Varying Severity

Effects of pressure gradients between branches of the left coronary artery on the pressure axis intercept and the shape of steady state circumflex pressure-flow relations in dogs.

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