The reliability of a modified videodensitometric and photodensitometric sampling technique for measuring phasic flow rates in the coronary artery system was examined. Electromagnetic flow measurements were performed in a circulatory model with continuous and pulsatile flow and intraoperatively in aortocoronary bypass grafts; cineangiograms were made simultaneously. Based on the front velocities of injected boluses of contrast medium, the densitometric measurement overestimated the electromagnetically measured flow systematically by about 20%. Systolic and diastolic flow rates in aortocoronary bypass grafts and coronary arteries determined from biplane cineangiograms in 34 patients generally revealed the typical pulsatile flow pattern familiar from electromagnetic and ultrasonic flow measurements. Flow velocities in unstenosed coronary arteries were nearly identical before and after branchings of the vessels, whereas the corresponding flow rates were higher in proximal than in distal segments. The identical flow velocities in different branches of the same vessel and the low variability of this parameter in different patients may be a suitable index of the effect of stenoses on coronary arterial blood flow. Circulation 68, No. 2, 337-347, 1983. THE SEVERITY of coronary artery disease is currently estimated by subjective evaluation of morphologic vessel abnormalities visualized by coronary angiography. Several methods have been used in the past to provide a quantitatiye means of measuring coronary blood flow in man, including indicator-dilution and radioisotope techniques as well as Doppler ultrasonic flow catheter measurements and densitometric evaluations of coronary angiograms. 1-8 Generally x-ray densitometry is based on the determination of the mean transit time of contrast medium. Mean transit time is defined as the difference between the mean appearance times of the contrast medium measured from the "densograms" (time function of x-ray density) at a proximal site and a distal site over the vessel.95In an attempt to avoid several methodologic difficulties inherent in this technique, we determined transit times from the fronts of the densograms (appearance From time) instead of the mean appearance time. The flow rates determined from the front velocities were compared with those flow values measured electromagnetically during the interval of the passage of the contrast medium. The measurements were performed in a model circulation and during coronary revascularization. From these examinations, the systematic deviation between electromagnetic and densitometric flow measurements was determined. In addition, the influence of the injected contrast medium on coronary artery flow was evaluated. The aim of this study was to establish the methodologic requirements for densitometric measurements of systolic and diastolic flow in the coronary artery system.
In the case reported it provided complete pain relief in a difficult pain problem. The was, however, no improvement in the pain or presence of the HPOA-associated gynaecosize of his gynaecomastia. mastia raised the possibility of a hormonal After one week he became reluctant to conaetiology for the clinical picture and perhaps tinue with twice daily injections and requested suggests that the symptomatic response to that the octreotide was stopped. Within 24 octreotide was because of a direct effect on the hours his symptoms had returned, prompting underlying disease mechanisms rather than a reintroduction of octreotide, this time 200 g primary analgesic effect. by a 24 hour subcutaneous infusion to avoid Octreotide may be a useful analgesic for the discomfort of repeated injections. He again treating the pain of HPOA when more conbecame pain-free and mobile, sufficient to enventional treatment has failed. It needs further able discharge home after only three days.evaluation, however, to determine its mechanism of action and thus enable identification of patients who are most likely to benefit. Discussion A B Figure 2 Computed tomographic scan of the chest showing (A) striking hypertranslucency of the left lung associated with an increase in volume and decrease in the diameter of the pulmonary vessels and (B) compression of the left mainstem bronchus by a 3.5 cm aneurysm of the descending aorta.studies showed an obstructive pattern with eurysms may be classified as arteriosclerotic, syphilitic, traumatic, dissecting, post-stenotic, forced expiratory volume in one second (FEV 1 ) 1.36 l (32% predicted), forced ventilatory cap-and mycotic. The cause of our patient's aneurysm was probably post-traumatic as he had acity (FVC) 1.91 l (38% predicted), forced mid expiratory flow ) 0.47 l (23% pre-had a chest trauma two years prior to his admission. Serological tests for syphilis were dicted), residual volume (RV) 258 l (161% predicted), and total lung capacity (TLC) 6.32 l negative.Aneurysms of the thoracic aorta may be (99% predicted). There was no response to an inhaled bronchodilator. The carbon monoxide found by chance on chest radiographs in an otherwise asymptomatic patient, or may preslung transfer factor (T) was 50% predicted, arterial oxygen tension (Pa 2 ) was 8.5 kPa, ar-ent as pain from aortitis, erosion of the sternum or vertebral column and compression of the terial carbon dioxide tension (Pa 2 ) 4.7 kPa, and pH 7.47.spinal nerves, or as symptoms arising from compression of adjacent structures. 4 ResVentilation-perfusion isotopic lung scans showed absence of ventilation and perfusion of piratory symptoms result from compression of the tracheobronchial tree. In some cases the left lung. Fibreoptic bronchoscopic examination revealed an extrinsic compression of compression may cause severe respiratory failure and indicate the need for emergency surthe left main bronchus. The rest of the bronchial tree was normal. A computed tomo-gery. 5 In most patients, as in our case, dyspnoea alone without chest p...
The evaluation of regional myocardial blood flow (RMBF) during cardiac catheterization is of particular diagnostic interest. The purpose of this investigation was to validate x-ray densitometric parameters for the evaluation of RMBF. In five anesthetized dogs, arterial flow in the circumflex coronary artery was measured continuously with an electromagnetic flowmeter, and RMBF was determined by colored microspheres. Five different perfusion levels were created by mechanical obstruction of the coronary artery or by intravenous infusion of adenosine. At each steady-state perfusion level, digital subtraction coronary angiograms were obtained for densitometric analysis. Results documented a close correlation between the related time parameters 1/Mean Transit Time (1/MTT, r2 = 0.969), and 1/Rise Time (1/RT, r2 = 0.965) and RMBF over a wide range between 0.36 ml/(min x g) and 11.16 ml/(min x g). Maximum myocardial contrast density (Imax) also showed a good, but inverse correlation (r2 = 0.889) with RMBF and, therefore, did not reflect vascular volume. Contrast medium Appearance Time (AT) showed no correlation to RMBF (r2 = 0.017). Repeat densitometric measurements for different perfusion levels revealed a good reproducibility for MTT (accuracy: 0.001 s; precision: 0.447 s or 6.7 %) and RT (accuracy: 0.014 s; precision: 0.202 s or 10.4 %), while AT (accuracy: 0.072 s; precision: 0.420 s or 68.5%) and Imax (accuracy: 0.022 GL; precision: 1.197 GL or 44.5%) showed substantial variation. Myocardial perfusion reserve (MPR) calculated from RT (r2 = 0.90) or MTT (r2 = 0.94) showed better correlations to RMBF reserve than MPR calculated from AT (r2 = 0.04). In conclusion, only 1/MTT and 1/RT showed a good reproducibility and a close correlation to RMBF. Therefore, only these parameters can be recommended for calculations of RMBF and its reserve under clinical conditions.
Distal embolization is the most important complication of balloon dilatation of degenerated saphenous vein grafts. We describe a case of massive embolization associated with transient occlusion in which larger distal embolization and myocardial infarction were avoided despite transient but complete occlusion of a filter protection system (Angioguard).
The relation between videodensitometrically measured front velocity and electromagnetically assessed flow was examined in a circulatory model with continuous as well as pulsatile flow (89 experiments). The diameter of the tubes in the videodensitometric measuring section was 0.305 to 0.518 cm. A linear correlation was proved in flow velocities up to Reynold's number Re = 225. The exact flow, measured electromagnetically, was overestimated in continuous flow by 21% (r = 0.99, Syx = +/- 14.5 ml/min) and in pulsatile flow by 24% (r = 0.98, Syx = +/- 20.8 ml/min). In view of these results the phasic and average flow can be calculated accurately using videodensitometric techniques.
To investigate whether left ventricular performance can be described independent of loading conditions, twelve patients underwent intraoperatively two cineangiographies of the left ventricle with simultaneous pressure recordings. The first ventriculography was performed with ejecting left ventricle without assistance by the extracorporeal circulation. The second one was performed with ejecting left ventricle partially unloaded by the extracorporeal circulation. Myocardial perfusion pressure (mean aortic pressure) was held constant. Due to this procedure marked decreases in preload (end-diastolic wall stress: -54%) and modest changes in afterload (mean systolic wall stress: -23%) were achieved. End-diastolic volume index was reduced from 84 ml/m2 to 57 ml/m2, whereas end-systolic volume index decreased slightly from 33 ml/m2 to 29 ml/m2. Left ventricular end-diastolic pressure decreased from 12 mm Hg to 7 mm Hg, while peak pressure remained nearly unchanged. Usual parameters of ejection phase (EF, Vmw) as well as power per wall volume (PW) were markedly affected by unloading. In contrast to these parameters, the power index (PI), i.e., the ratio of power per wall volume and end-diastolic wall stress, remained unchanged when left ventricular preload was reduced: PI under control: 5.2 +/- 1.8 sec-1; PI under unloading: 5.2 +/- 1.5 sec-1. This power index can easily be determined from routine angiographies. It may provide a new approach to the assessment of left ventricular function in man.
Electromagnetic flow measurements in aorto coronary bypass grafts and cine angiography were performed simultaneously during bypass surgery. Using the front velocities of injected boli of contrast medium the videodensitometric measurement (QVD) overestimates the electromagnetically measured flow (QEM) systematically about 20% (QVD = 1.26 . QEM = 4 ml/min; Syx = 10.8 ml/min; r = 0.97). During the passage of the front of the contrast medium through the videodensitometric measuring windows, the flow is altered by the injection about + 13.6 ml/min on an average.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
334 Leonard St
Brooklyn, NY 11211
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.