Maximizing myocardial perfusion with combined dipyridamole and phenylephrine
Intravenous dipyridamole (DP), a potent coronary vasodilator, has been used as a pharmacological exercise substitute for Thallium scintigraphy. Increased coronary artery flow occurs in animals. Humans with severe coronary disease have been imaged with Thallium using this technique. However, in both animals and man, the systemic blood pressure decreases especially at higher dosages. Myocardial perfusion (MP) is dependent on delivery pressure as well as the diameter of the coronary artery. The authors therefore maintained blood pressure by infusion of phenylephrine (PE) during maximal coronary artery dilatation from DP. Seven anesthetized, mongrel, open chest dogs weighing 20-25 kgs were infused with DP alone, 0.075 mg/kg/min for 10 minutes. Mp was measured in a highly localized small volume (0.5 cm/sup 3/) of myocardium using a silicon avalanche radiation detector to record the washout of a 2-5 mCi bolus of xenon in saline using the Kety-Schmidt formula. Polyethylene tubing (O.D. 0.03 inches) was directed into the proximal LAD using a brass canula introduced through the carotid artery. In 5 other dogs, 0.1 mg of PE was added to the DP. DP alone caused only a minor elevation of MP (15%) while the blood pressure decreased. In contrast with PE, the pressure was maintained and MP more than doubled. With continued infusion, both pressure and MP fell. In conclusion, elevation of MP by a coronary dilator DP can be enhanced when combined with a vasopressor (PE) and may be better for pharmacological stimulation of MP for Thallium imaging. Prolonged administration of DP may decrease rather than increase MP even during infusion of phenylephrine.
- Research Organization:
- Veterans Administration Medical Center, Long Beach, CA
- OSTI ID:
- 7088957
- Report Number(s):
- CONF-840619-
- Journal Information:
- J. Nucl. Med.; (United States), Vol. 25:5; Conference: 31. annual meeting of the Society of Nuclear Medicine, Los Angeles, CA, USA, 5 Jun 1984
- Country of Publication:
- United States
- Language:
- English
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DOGS
MYOCARDIUM
DRUGS
DIAGNOSTIC USES
LABELLING
MYOCARDIAL INFARCTION
DIAGNOSIS
SCINTISCANNING
THALLIUM 201
BLOOD PRESSURE
CORONARIES
HUMAN POPULATIONS
IMAGE PROCESSING
INTRAVENOUS INJECTION
PRESSURE DROP
VOLUME
XENON
ANIMALS
ARTERIES
BETA DECAY RADIOISOTOPES
BLOOD VESSELS
BODY
CARDIOVASCULAR DISEASES
CARDIOVASCULAR SYSTEM
COUNTING TECHNIQUES
DAYS LIVING RADIOISOTOPES
DIAGNOSTIC TECHNIQUES
DISEASES
ELECTRON CAPTURE RADIOISOTOPES
ELEMENTS
FLUIDS
GASES
HEART
HEAVY NUCLEI
INJECTION
INTAKE
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
MAMMALS
MUSCLES
NONMETALS
NUCLEI
ODD-EVEN NUCLEI
ORGANS
POPULATIONS
PROCESSING
RADIOISOTOPE SCANNING
RADIOISOTOPES
RARE GASES
SECONDS LIVING RADIOISOTOPES
THALLIUM ISOTOPES
USES
VERTEBRATES
550601* - Medicine- Unsealed Radionuclides in Diagnostics