Mean transit time for the assessment of myocardial perfusion by videodensitometry.

Abstract

The intrinsic limitations of coronary arteriography to predict the physiological effects of coronary obstructions are well known. Therefore, more direct assessments of the functional significance of coronary stenoses are becoming increasingly important. Study of contrast passage by electrocardiogram-triggered digital radiography has been proposed as a way of assessing changes in myocardial perfusion. The main problems in this approach are the limited time for motionless image acquisition, the potential alteration of vascular volume between different states, and the changing flow pattern induced by contrast agents. This has led to empiric substitution of mean transit time (Tmn) by other time parameters and to representation of vascular volume by maximal contrast intensity (D..). To avoid these problems, intact dogs were studied during almost motionless image acquisition of 20-25 consecutive paced heart beats obtained with synchronous radiographic pulses. In (weight, 26-36 kg) were anesthetized with sodium pentobarbital 25 mg/kg i.v., a left thoracotomy was performed, and epicardial pacing electrodes were sutured on the left atrium. The proximal part of the left circumflex artery (LCx) was gently dissected free, over a distance of 1.0-1.5 cm proximal of the origin of the first large obtuse marginal branch. A ring-mounted 20-MHz pulsed Doppler probe (Crystal Biotech Inc., Holliston, Massachusetts) was placed around the artery and a circular balloon occluder (R.E. Jones, Silver Springs, Maryland) was placed just distal to the Doppler probe. The pericardium and chest were closed, and the instrumentation leads were placed in a subcutaneous pocket until the time of study.At day 11 after instrumentation, each dog was anesthetized by nicomorphine 10 mg/hr i.v. and ethrane. The subcutaneous pocket was opened, and the wires of the Doppler probe were connected to the appropriate recording equipment (545C-4 Directional Pulsed Doppler Flowmeter, Department of Bioengineering, University of Iowa, Iowa City, Iowa). The pacing electrodes were attached to a trigger unit (Department of Bioengineering, University of Nijmegen, The Netherlands) and the occluder tube was connected to a 5-ml syringe. Both femoral arteries were dissected free. An 8F pigtail manometer catheter (Millar microtipped-catheter transducer SPC-780C) was introduced into the left femoral artery and positioned for simultaneous pressure recording in the left ventricle and the ascending aorta. A 5F left Judkins catheter was introduced into the right femoral artery and advanced into the ostium of the left main coronary artery. Electrocardiogram, left ventricular pressure and its first derivative, aortic pressure, and phasic and mean coronary blood flow velocity in the LCx were recorded on an eightchannel recorder (Hewlett-Packard).After intravenous infusion of 5 mg propranolol during 20 minutes to prevent disproportionate increase in heart rate, an initial dose of dipyridamole (0.75 mg/kg) was administered intravenously during 4 minutes to create maximal dilation ...

Quantification of coronary microvascular resistance using angiographic images for volumetric blood flow measurement: in vivo validation

“…Several previous studies have evaluated coronary blood flow by using angiographic images. Pijls et al (40,41,42) measured the mean transit time for the assessment of myocardial perfusion by videodensitometry. Molloi et al (35,37) have shown that the FPA analysis technique can be used to measure absolute coronary blood flow by analyzing the propagation of a contrast material signal in the coronary system.…”

Acute type A aortic dissection in an adult patient with Turner's syndrome

“…7 Coronary angiographic video densitometry has been evaluated in patent vessels using the mean transit time of contrast clearance to assess myocardial perfusion, according to the principles of indicator dilution theory. 8 Based on these considerations, we sought to develop a more exact, inexpensive, and easy to apply angiographic method for characterising coronary collaterals. Our aim in this study was to test the hypothesis that the time to clearance or washout of radiographic contrast medium trapped distal to an occluded collateral receiving vessel is inversely related to collateral flow, and that this provides an accurate method of characterising coronary collaterals (figs 1 and 2).…”

Computerized quantitative assessment of myocardial perfusion on coronary angiograms

“…In most previous studies [Pijls 1990] [Korosoglou 2007], myocardial ROI was smaller than in our method. We have chosen to include the whole distribution bed of the infarct-related vessel in the ROI because the distribution of contrast material in the myocardium is usually not homogeneous.…”

“…Pijls et al used least squares minimization with gammadistribution function [Pijls 1990]. A two-compartment mathematical model was also proven to be useful for regional perfusion assessment in a canine model [Eigler 1989] and later in humans [Schühlen 1994].…”

“…Ultrasonic and electromagnetic flow meters were used to validate measurements [Eigler 1989] [Pijls 1990]. …”