Improved technique for implanting electromagnetic flowmeter probes on the coronary artery.

Alexander, J. T.; Wc, Sealy; Greenfield, Jr Jc

doi:10.1152/jappl.1969.27.1.139

Cited by 18 publications

(9 citation statements)

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“…A 2.5-to 3.5-mm Howell ST-type electromagnetic flowmeter probe (Howell Instruments, Camarillo, Calif.) and a pneumatic occluder were positioned on the proximal left circumflex coronary artery (12). The proximal end of the catheters, the occluder, and the leads to the electromagnetic flowmeter probe were tunneled to the base of the neck and placed in a subcutaneous pouch.…”

Section: Methodsmentioning

confidence: 99%

Myocardial Blood Flow Distribution in Concentric Left Ventricular Hypertrophy

Rembert¹,

Kleinman²,

Fedor³

et al. 1978

J. Clin. Invest.

163

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A B S T R A C T Regional myocardial blood flow during both control conditions and ischemia-induced vasodilatation was studied in eight chronically instrumented awake dogs. Seven of these animals had coarctationbanding ofthe ascending aorta performed at 6 wk of age, and the other dog had congenital subvalvular aortic stenosis. The mean left ventricular weight for the group was 157±7.6 g, and the left ventricular body weight ratio was 8.76+0.47 g/kg. None ofthe animals exhibited signs of congestive heart failure.During the control state, the mean left ventricular systolic pressure was 249+12 mm Hg and the left ventricular end-diastolic pressure was 11.5±0.5 mm Hg. The aortic diastolic pressure was 74±6 mm Hg. Mean left circumflex coronary artery blood flow was 71±6 cm3/min. In the animals with coarctation-banding, 52±6% of the flow occurred during systole. In the dog with congenital subvalvular aortic stenosis, 5% of the coronary flow was systolic. Mean transmural blood flow during resting conditions was 0.97±0.08 cm3/min per g, and the ratio of endocardial to epicardial flow (endo/epi) was 0.88±0.07. During reactive hyperemia, the mean transmural blood flow increased to 3.5±0.30 cm3/min per g; however, the endo/epi decreased to 0.52±0.06.These studies document a difference in transmural blood flow distribution between the normal and the hypertrophied left ventricle: during resting conditions, in the normal ventricle, the highest flow occurs in the endocardial layer, whereas in the hypertrophied ventricle, the highest flow is in the middle layers with the endocardial flow less than the epicardial flow.

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Section: Methodsmentioning

confidence: 99%

Myocardial Blood Flow Distribution in Concentric Left Ventricular Hypertrophy

Rembert¹,

Kleinman²,

Fedor³

et al. 1978

J. Clin. Invest.

163

View full text Add to dashboard Cite

show abstract

Section: Methodsmentioning

confidence: 99%

“…Care was taken to attain mechanical stability of the flow probe on the coronary artery to ensure a consistently stable baseline during later coronary flow measurements. 6 An inflatable cuff-type hydraulic occluder constructed in our laboratory of polyvinyl chloride tubing (o.d., 2.7 mm) was placed around the circumflex coronary artery distal to the electromagnetic flowmeter probe.7 Injection of water into the occluder tubing with a tuberculin syringe allowed precisely controlled partial inflation of the occluder to cause reproducible restriction of coronary artery inflow. The electromagnetic flowmeter leads, aortic and left atrial catheters, and hydraulic occluder tube were tunneled dorsally into a subcutaneous pouch at the base of the neck but were not exteriorized to protect them from damage.…”

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confidence: 99%

Distribution of myocardial blood flow in the exercising dog with restricted coronary artery inflow.

Ball¹,

Bache²

1976

Circulation Research

106

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SUMMARY The effect of a proximal coronary artery stenosis on transmural myocardial blood flow during exercise was studied in nine dogs with electromagnetic flowmeter probes and hydraulic occluders on the left circumflex coronary artery. Regional myocardial blood flow at rest and during treadmill exercise was estimated with radioactive microspheres 7-10 j»m in diameter. Exercise studies were performed during unrestricted coronary artery inflow (control exercise) and during partial inflation of the occluder to a level which did not reduce flow at rest but which limited the increase in flow during exercise to 66 ± 6% (mild restriction) or 44 ± 3% (severe restriction) of the value during control exercise. Mean myocardial blood flow at rest was 0.94 ± 0.06 rnl/min per g of myocardium and increased to 2.45 ± 0.15 ml/min per g during control exercise, with uniform distribution across the wall of the left ventricle. Flow to the subepicardial myocardium was significantly greater during exercise in the presence of a mild restriction than during control exercise, whereas flow to deeper layers of myocardium was progressively decreased below the control level. A similar pattern of redistribution of flow occurred during exercise in the presence of a severe restriction, but flow to all transmural layers was below that during mild restriction, resulting in more marked subendocardial underperfusion. Thus, exercise in the presence of stenosis resulted in transmural redistribution of myocardial blood flow with subendocardial underperfusion in proportion to the degree of restriction of coronary artery inflow.IN THE presence of occlusive coronary artery disease patients who have normal electrocardiograms at rest may develop S-T segment depression during exercise, often in association with chest pain. This electrocardiographic change suggests that in these patients exercise may result in selective ischemia of the subendocardial myocardium.1 Previous experimental studies in animals have demonstrated that in contrast to the uniform left ventricular perfusion that exists during unimpeded coronary artery inflow, transmural redistribution of flow may occur during restricted inflow. Thus, in open-chest dogs reduction of coronary inflow below the metabolic requirements of the myocardium resulted in transmural redistribution of myocardial blood flow with preferential underperfusion of the subendocardial myocardium.2 " 6In patients with occlusive coronary artery disease, arterial inflow at rest may be adequate and transmural distribution uniform, but because arterial inflow is unable to increase adequately during exercise a similar redistribution of myocardial blood flow may occur with preferential underperfusion of the subendocardial myocardium. The present study was an attempt to determine whether, in an experimental model with a flow-limiting proximal coronary artery stenosis, exercise could result in the proposed redistribution of myocardial blood flow. MethodsNine adult mongrel dogs weighing 22-34 kg were anesthetized with sodium thiamyl...

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“…In this situation, during the interval when coronary flow was restricted to the preocclusion control level considerable capacity to increase oxygen extraction would exist and the blood flow debt might, at least in part, have been repaid by increasing oxygen extraction without need for further increase of coronary blood flow. In man, nitroglycerin has been demonstrated to decrease left ventricular volume secondary to reduction of arterial pressure as well as to decreased venous return resulting from systemic venodilation (10,20). Reduction of left ventricular volume would result in decreased left ventricular systolic tension development, a major determinant of myocardial oxygen consumption (21).…”

Section: Effects Of Nitroglycerin On Transmural Myocardial Blood Flowmentioning

confidence: 99%

Effects of nitroglycerin on transmural myocardial blood flow in the unanesthetized dog.

et al. 1975

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AB STRA CT This study was designed to determine the effect of nitroglycerin upon transmural distribution of myocardial blood flow in the awake dog during normal conditions and in the presence of ischemia-induced coronary vasodilation. Studies were performed in chronically prepared dogs with electromagnetic flowmeters and hydraulic occluders on the left circumflex coronary artery. Regional myocardial blood flow was estimated by using radionuclide-labeled microspheres, 7-10 im in diameter, injected into the left atrium. During control conditions endocardial flow (0.86±SEMI 0.05 ml/min per g) slightly exceeded epicardial flow (0.72±0.03 ml/min per g, P < 0.05), and this distribution of flow was not significantly altered by nitroglycerin. After a 5-s coronary artery occlusion, reactive hyperemia occurred with excess inflow of arterial blood effecting 360+15 15% repayment of the blood flow debt incurred during occlusion. When arterial inflow was limited to the preocclusion rate during coronary vasodilation after a 5-s total coronary artery occlusion, flow to the subepicardial myocardium was increased at the expense of underperfusion of the subendocardial myocardium, and the delayed reactive hyperemia was markedly augmented (mean blood flow debt repayment = 775±105%, P < 0.01). These data suggested that subendocardial underperfusion during the interval of coronary vasodilation in the presence of a flow-limiting

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Improved technique for implanting electromagnetic flowmeter probes on the coronary artery.

Cited by 18 publications

References 0 publications

Myocardial Blood Flow Distribution in Concentric Left Ventricular Hypertrophy

Myocardial Blood Flow Distribution in Concentric Left Ventricular Hypertrophy

Distribution of myocardial blood flow in the exercising dog with restricted coronary artery inflow.

Effects of nitroglycerin on transmural myocardial blood flow in the unanesthetized dog.

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