Bo M. T. Lantz

Noninvasive blood flow measurements by doppler ultrasound with applications to renal artery flow determination

A description of a new Doppler ultrasound flow measuring instrument is given along with representative measurements of blood flow in the canine renal artery and the human aortic arch, renal artery, and transplanted kidney renal artery. The instrument is briefly described, and a discussion of the limitations of the technique is presented.

Effect of Respiration on Cardiac Motion Determined by Cineangiography: Implications concerning Three-Dimensional Heart Reconstruction Using Computer Tomography

Based on 39 cineangiographies in 23 patients performed during respiration with tracing of the cardiac chambers and the diaphragm, it has been found that the heart moves significantly with respiration, approximately half as much as the diaphragm during shallow or normal respiration. The cardiac respiratory motion indicates that gating of the respiratory cycle as well as the cardiac cycle is necessary in three-dimensional reconstruction of the heart using a large number of heart beats for recording.

Determination of Blood Flow through Arteriovenous Fistulae and Shunts

A videodensitometric method for estimating relative flow was employed in a patient with a bovine arteriovenous fistula. Analogous arteriovenous communications of different sizes were created in two dogs for comparison. Local and general hemodynamic parameters were measured. The videodensitometric method proved to be highly accurate compared to electromagnetic flow readings and is the method of choice in estimating shunt flow in connection with routine angiography.

Venous return and the pneumatic antishock garment in hypovolemic baboons

The pneumatic antishock garment is widely used in trauma patients because it compresses small veins and should augment venous return. If the garment does augment venous return, it should probably be used in all injured patients in shock, regardless of injuries and regardless of anticipated transport time. On the other hand, the garment could distort and narrow large retroperitoneal and abdominal veins and impede venous return. We quantitated venous return in normovolemic and hypovolemic baboons. The garment both augmented and impeded venous return, the two effects counteracting each other. We believe that the pneumatic antishock garment should be used selectively.

Angiographic determination of splanchnic blood flow.

A new videodensitometric method of measuring blood flow in the splanchnic arteries as a fraction of the cardiac output was compared to electromagnetic flow readings in dogs. A previous investigation regarding the accuracy of the method in vitro was extended to prove that the videodensitometric technique was highly accurate also in vivo. The simplicity of the technique suggests that the videodensitometric method could be used to estimate blood flow in splanchnic arteries during routine angiography.

On-Line Monitoring of Sequential Blood Flow Reduction during Splenic Embolization

Partial embolization of the spleen has been well established for the treatment of hypersplenism. A weakness of the technique is the lack of an objective method to quantitate the flow reduction during the procedure. The video dilution technique (VDT) has earlier been used to measure blood flow in regional arteries using video cassette replay. By adapting the VDT concept of relative flow to digital subtraction angiography, it is possible to calculate the flow reduction instantly following each injection of embolic material. We present a case of partial splenic embolization where the flow in the splenic artery was reduced to a predetermined level of 50 per cent of baseline flow. The clinical results were excellent. By observing the clinical results of partial embolization, terminated at different levels of flow reduction, it will be possible to optimize the results and prevent overembolization.

Angiographic measurement of coronary blood flow by video dilution technique.

A simplified video dilution technique has been developed whereby neither coronary dimensions nor contrast velocity need be measured to obtain coronary blood flow relative to a control flow. In 6 dogs, the distal left anterior descending coronary artery flow was measured by simultaneous electromagnetic flowmeter and video dilution technique. For the 236 paired measurements, the electromagnetic flow ranged from 23 to 196 ml/min for each series. When the first measure of a series was considered the control, the flow ratio difference between electromagnetic and video dilution values had a standard deviation of 12 per cent. When each series was broken into pairs, flow ratio difference between these values had a standard deviation of 10 per cent. Thus, the video dilution technique allows accurate measurement of coronary blood flow relative to a control state, utilizing only the known amount of contrast medium injected and the image from videotape replay of the injection. A patient is presented to illustrate the technique during coronary angiography. Applications include determination of coronary reserve during reactive hyperemia to assess the hemodynamic significance of coronary lesions, and determination of the effects of drugs upon coronary blood flow.

New videodensitometric method for measuring renal artery blood flow at routine arteriography: validation in the canine model.

A contrast medium was injected in the aortic arch and selectively in a renal artery to estimate the renal blood flow as a percentage of the cardiac output by the videodensitometric (VD) method. Twenty-six paired VD measurements in four mongrel dogs were obtained and the results compared to electromagnetic (EM) flow readings from the aortic arch and a renal artery. The relative renal blood flow estimated by the VD method averaged 9.1% and correlated with the EM flow average of 9.6% with r = 0.96. Previous in vitro investigations of relative flow in a model have now been validated in vivo. These results suggest that videodensitometry could be a clinical tool for measuring renal blood flow in conjunction with routine arteriography.

Assessment of peripheral blood flow in man by video dilution technique: a preliminary report.

Video dilution technique is now available for clinical use in evaluating patients with peripheral vascular disease. The measurements can easily be performed in any modern angiographic suite. The only additional equipment required is a videodensitometer, video tape recorder, and a strip chart recorded. The new technique has been developed and tested in a hydrodynamic model and compared to volumetric flows. Further, the video dilution technique has been compared to electromagnetic flow readings using a canine model to measure the cerebral, renal, splanchnic, and extremity circulation and has proven to be extremely accurate (n = 389; r = 0.99). By applying the technique to patients with peripheral vascular disease, it is possible to evaluate the hemodynamic significance of stenotic lesions and arteriovenous shunts. Other uses of video dilution technique include evaluating the effects of vasoactive drugs and the adequacy of transluminal angioplasty.

Aortic compliance in hypercholesterolemic Watanabe rabbits compared to normal New Zealand controls.

This study was designed to test the hypothesis that severe atherosclerosis changes aortic compliance. Compliance of a vessel is defined as change in volume per unit change in pressure and is a measure of the stiffness or distensibility of the vascular wall. Part of the energy delivered by the left ventricle in systole is used to propel the blood forward into the aorta and part of it to distend the aorta and major vessels. During diastole, the arterial walls recoil and provide energy for propulsion of blood, thereby making blood flow continuous. It is known that Watanabe hereditary hyperlipidemic rabbits develop severe atherosclerosis beginning at 6 months of age. Compliance of the ascending thoracic aorta was studied angiographically in eight Watanabe hereditary hyperlipidemic rabbits of ages greater than 6 months and six normal lipidemic New Zealand white rabbits of ages greater than 6 months, used as controls. The normal New Zealand white rabbits had an average blood cholesterol of 27.4 mg/dL, SD = 13.8, and a regional compliance in the ascending aorta of 0.004 mL/mm Hg, SD = 0.002, compared to the Watanabe hereditary hyperlipidemic rabbits with a cholesterol of 583.1 mg/dL, SD = 162.7, and a compliance of 0.0022 mL/mm Hg, SD = 0.0015. These are significant differences (p less than .05). In addition, the histopathology of the aorta of the Watanabe hyperlipidemic rabbit compared to that of the controls showed a significant decrease in the number of medial lamellar elastin units, an indicator of the decreased elasticity of the blood vessel wall.