Doppler Ultrasound Flowmeter Research Articles

Doppler Ultrasound Flowmetry Predicts 15 Year Outcome in Patients with Skin Melanoma

This prospective cohort study was conducted to find the role of tumor neovascularization in skin melanoma measured by preoperative Doppler ultrasound flowmetry in determining the 15-year outcome. Department of Surgery, University of Wales College of Medicine, Cardiff, UK. Seventy-one primary melanomas in 67 patients were studied with a 10MHz Doppler ultrasound flowmeter. The flow signals were recorded on an audiotape. The peak systolic frequency, mean systolic frequency, and minimum diastolic frequency were measured on a spectrum analyzer. The follow-up (median 144months) information is complete till December 2005 on 63 patients. Blood flow signals were detected in 41 lesions; these were labeled Doppler flow positive. No flow was detected in 22 lesions, labeled Doppler flow negative. Among the Doppler flow positive group, 39% patients have died with metastatic melanoma, whereas none of the patients with a Doppler-negative lesion have died or developed any recurrence. Higher peak systolic frequency (above 2,500MHz.) was associated with a hazard ratio for death due to melanoma of (HAZARD RATE = 5.99). Higher risk of death, locoregional, and systemic recurrences were associated with higher peak systolic frequency. Doppler flowmetry performed preoperatively is a noninvasive, quick, and simple method to assess tumor blood flow which may help in predicting long-term survival and planning neoadjuvant therapies aimed at inhibiting angiogenesis or targeting tumor vasculature.

Doppler ultrasound as an adjunct to the differential diagnosis of pigmented skin lesions

One hundred and forty-one pigmented skin tumours were examined with a 10 MHz ultrasound Doppler flowmeter to investigate the value of detecting blood flow in the diagnosis of raised pigmented skin lesions. Most of the benign lesions except for those with an angiomatous basis were devoid of blood flow signals while all basal cell carcinomas and 96 per cent of thick melanomas (greater than or equal to 0.9 mm) were associated with detectable Doppler frequency shift signals. While the characteristics of analysed Doppler waveforms are of research interest, the simple detection of blood flow by a hand held instrument gives sufficient information for clinical purposes. In practice this simple test has been sufficiently reliable to prove a useful adjunct in the diagnosis of raised pigmented skin lesions. It has been found particularly helpful in the common clinical problem of differentiation of nodular melanoma from basal cell papilloma and benign intradermal naevus. If such a lesion is thought to be benign, and has detectable flow signals, one should reconsider the diagnosis. Absence of flow signals is strong confirmation of a benign clinical diagnosis. The test should be regarded as an adjunct to clinical diagnosis since, in common with all noninvasive diagnostic techniques, false negative and false positive cases will be encountered. The technique is not appropriate to macular lesions since these are usually flow negative, irrespective of the pathology.

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NONINVASIVE BLOOD PRESSURE MONITORING IN PATIENTS WITH CONTINUOUS FLOW ROTARY LVAD

Recently, clinically implantable rotary blood pumps made it possible to support patients for extended time periods in full mobility, without the necessity of any invasive catheters. However, low pulsatility of arterial blood pressure, compromises determination of this important parameter by the classical Riva-Rocci cuff pressure-method:. Therefore, the Riva-Rocci blood pressure measurement was modified using an Ultrasound Doppler flowmeter instead of a microphone to determine the pinch-off point of peripheral flow. A continuous wave Doppler-flowmeter (Huntleigh® DopplerII) with a bidirectional data display was used. Comparisons with invasive measurement showed good agreement, with the doppler-determined values below below the systolic value of invasive monitoring. Depending on pulsatility ratio a difference of less than 5 to 10mmHg was observed. To allow single-hand use of the equipment, the ultrasound sensor can be mounted on a guiding splint for proper positioning above the radial artery. It is concluded that this method allows reliable, noninvasive determination of arterial pressure in daily routine of rotary-pump assisted patients.

Intraoperative hemodynamic assessment of gastroepiploic artery and saphenous vein bypass grafts: A comparative study

Objective: Blood flow characteristics of right gastroepiploic artery and saphenous vein conduits were compared during bypass surgery. Methods: This study is based on a consecutive series of 97 patients undergoing a bypass graft to the right coronary artery, posterior descending artery, or posterolateral branch using either a pediculated right gastroepiploic artery (n = 52) or a saphenous vein (n = 45) bypass graft. Flows and velocity profiles were measured with an 8-MHz pulsed-wave Doppler ultrasound flowmeter. Thorough flow measurements were made (1) after cessation of cardiopulmonary bypass and (2) before chest closure. Results: At the end of cardiopulmonary bypass, flow in the right gastroepiploic artery (59.0 ± 6.7 mL/min) did not differ ( P = .08) from flow in the saphenous vein (46.1 ± 2.7 mL/min). Mean trace velocity was 11.9 ± 0.7 cm/s in the right gastroepiploic artery and 11.6 ± 0.8 cm/s in the saphenous vein ( P = .80), but peak systolic velocity was 29.4 ± 1.2 cm/s for the right gastroepiploic artery and 23.1 ± 1.3 cm/s for the saphenous vein ( P < .001). Likewise, before chest closure, flow was 57.1 ± 4.7 mL/min in the right gastroepiploic artery and 46.5 ± 4.0 mL/min in the saphenous vein ( P = .10), mean velocity was 12.9 ± 0.7 and 11.6 ± 0.8 cm/s, respectively ( P = .22), and systolic peak velocity was 30.0 ± 1.2 and 22.3 ± 1.2 cm/s, respectively ( P < .001). Conclusions: There were no flow differences between right gastroepiploic artery and saphenous vein grafts implanted into the same coronary bed in comparable groups of patients. Waveform shape of the right gastroepiploic artery grafts was characterized by a wider spectral dispersion resulting in a higher maximal frequency. (J Thorac Cardiovasc Surg 1999;118:330-8)

EFFECT OF TREATMENT OF LIDOCAINE, PROSTAGLANDIN PGE OR CHLORPROMASINE ON POST-ISCHEMIC RENAL BLOOD FLOW AND KIDNEY FUNCTION.

309 The effect of intraarterial administration of lidocaine, prostaglandine E1 or chlorpromasine on renal blood flow, parenchymal microcirculation and post-ischemic function after acute warm kidney ischemia was investigated. Seventy rats, uni-nephrectomised one month before investigation, were operated under general anaesthesia. Renal vessels were occluded for 90 minutes. Animals were divided into groups of ten rats each. Rat in the first group received 200 μg/kg/min of PGE1, in the second - lidocaine 1 mg/kg in bolus followed by 0.1 mg/min, and in the third - chlorpromasine 2 mg/kg intraarterialy in bolus followed by 0,06 mg/kg infusion during 30 min prior to renal vessels occlusion. Groups IV, V and VI received the same doses of PGE1, lidocaine or chlorpromasine during 30 min after revascularisation. The control groups were treated the same way with 1ml 0,9% NaCl. Renal blood flow (RBF) was measured using ultrasound Doppler flowmeter, renal cortical blood flow (CBF) was measured with laser-doppler flowmeter. Vascular resistance (VR) was calculated from the blood flow and mean arterial pressure. Rats were observed for 21 days in metabolic boxes; serum creatinine concentration and clearance were measured. Results. Mean results of RBF, CBF and VR in all groups 60 min after revascularisation (table). The highest RBF as well as CBF and lowest VR after revascularisation and complete recovery to pre-clamping values were observed after pre-clamping PGE1 administration. Return to normal creatinine and clearance values was better in this group and nine of ten rats survived the experimentTableConclusions. The highest renal blood flow and cortical flow were observed after pre-clumping PGE1 administration and they correlated with the best post-operative kidney recovery. Despite slightly worse results after lidocaine administration its effect deserves attention due to its incomparably lower cost.

Effect of anastomosis and geometry of vessel curvature on blood flow velocity and patency in microvessels.

The effect of the geometry of the vessel and the number of anastomoses on the blood flow was studied. Four different shapes of the vessel were constructed by using a 6-cm-long double vein graft model with three anastomoses: (1) an alpha loop, (2) an omega loop, (3) a sigmoid curve, and (4) straight. Blood flow was measured by an ultrasound Doppler flowmeter. The result showed no alternation in blood flow across different geometry and through three patent microanastomoses. However, six out of seven vein grafts were thrombosed at 24 hr postoperative due to vascular kinks. This model demonstrates potential sites of kinking at the dissection end of the femoral artery, the microanastomoses, the side branches of the vein graft, and the adventitial adhesions. This model is recommended to microvascular trainees for the study of kinking and the management of redundant pedicles and vein grafting.

The use of Doppler ultrasound in the clinical management of acute testicular pain

To evaluate the reliability and the clinical application of the use of a hand-held Doppler ultrasound flowmeter probe as an aid to differential diagnosis in the assessment of cases with acute testicular pain presenting to a district general hospital. Over a period of 1 year, testicular Doppler ultrasonic assessment was performed on 56 patients admitted with acute scrotal pain. A hand-held Doppler ultrasound probe was used, with a transducer operating at 8 MHz. All the patients were assessed pre-operatively by a single operator in the Accident and Emergency department before transfer to theatre. The decision to explore the testis was made purely on clinical grounds by which ever emergency surgical team was on duty. The operating surgeons were not informed of the result of Doppler examinations before surgical exploration. Twenty-two patients were subsequently shown to have torsion of the testis at surgical exploration, all of whom had no Doppler signal over the affected side. Of the remaining 34 patients, who were subsequently shown not to have torsion at operation, normal testicular blood flow and cord-compression tests were demonstrated confidently in 33 patients when examined pre-operatively. Thus the sensitivity was 100% (22/22) and the specificity 97% (33/34). Testicular Doppler examination using an 8 MHz probe in conjunction with the cord-compression test is a useful, simple and highly accurate clinical tool which can differentiate between testicular torsion and other conditions presenting with acute testicular pain. It is also inexpensive and readily available in the district general hospital situation.

Determination of Doppler Probe Angle In Pulsed Ultrasonic Doppler Flowmeter

Ultrasound Doppler flowmeters are widely used to measure blood flow velocity in medical practice. For quantitative measurement of blood flow velocity, the Doppler probe angle has to be determined because the principle of the Doppler flow measurement is dependent on the angle between ultrasound beam and the axis of blood vessel. The purpose of this paper is to present a technique to determine the Doppler probe angle using a standard ultrasound pulsed Doppler blood flowmeter without the requirement of a specially designed probe. The technique is based on the determination of vessel position with respect to the skin surface. Experimental results show high accuracy of the method in a vessel-skin angle range of 5-40^{o}.

Hemodynamic changes in blood flow through the denervated liver in pigs.

We investigated the effects of liver denervation on hemodynamic circulation in seven anesthetized pigs. Simultaneous measurements of the hepatic artery and portal vein were performed with an ultrasound Doppler flow meter before and after liver denervation. Neither resting systemic nor hepatic hemodynamics changed following liver denervation. However, temporary occlusion of the portal vein resulted in a significant increase in hepatic artery flow in the innervated liver (from 123 +/- 15 ml/min to 177 +/- 17 ml/min, p < .01), whereas, in the denervated liver, a significant decrease was observed (from 128 +/- 11 ml/min to 106 +/- 19 ml/min, p < .05). Thus, the reciprocity between the hepatic artery and portal vein in the hepatic artery flow during portal vein occlusion might intensify symptoms of portal vein thrombosis in liver transplantation. In the denervated liver, a significant decrease also occurred in systolic blood pressure and central venous pressure from 1 to 3 min after portal vein occlusion. Since the liver plays a crucial role in the maintenance of cardiovascular homeostasis during blood loss, it is likely that denervation at the porta hepatis induced a lack of vasoconstriction in the portal territory. Liver denervation might further exacerbate this response to hypotension. The current study confirms that the hepatic nerves play an important role in hepatic arterial and portal venous interactions aimed at maintaining a constant blood flow through the liver. We also suggest that the hepatic nerves are important for cardiovascular homeostasis.

The Effect of Nicardipine on Carotid Blood Flow Velocity, Local Cerebral Blood Flow, and Carbon Dioxide Reactivity During Cerebral Aneurysm Surgery

We studied the effects of nicardipine (initial infusion rate 0.5 μ·kg−1·min−1) on blood flow velocity in the internal carotid artery, local cerebral blood flow (LCBF), and carbon dioxide reactivity in 20 patients undergoing craniotomy for cerebral aneurysm clipping under isoflurane anesthesia. The blood flow velocity in the internal carotid artery was measured at T0 and T3 by a 20-MHz pulsed ultrasound Doppler flowmeter. LCBF was measured by the thermal gradient blood flow meter. Group A consisted of 10 patients with a good neurologic status (Hunt and Kosnik Grade I); Group B consisted of 10 patients with a poor status (Grades II-IV). Nicardipine was infused until the mean arterial blood pressure decreased to about 75% of the initial value and was maintained at this level until the completion of aneurysm clipping. The measurements of hemodynamics and LCBF were performed after the exposure of the internal carotid artery (T0), and 10 and 30 min after the start of nicardipine (T1 and T2, respectively), before aneurysm clipping (T3), and 30 min after its discontinuation (T4). Carbon dioxide reactivity [% ÂLCBF/ÂPaCO2 (% / mm Hg)] was evaluated at T0, T3, and T4. Mean arterial blood pressure decreased after nicardipine infusion in both groups. LCBF did not change during nicardipine infusion in either group. Blood flow velocity increased significantly in Group A after nicardipine infusion from 45.1 ± 6.9 to 51.5 ± 6.4 cm/s (P < 0.05), but in Group B flow velocity did not change. Carbon dioxide reactivity did not change after nicardipine infusion but correlated with LCBF before (r2 = 0.495, P < 0.05), during (r2 = 0.706, P < 0.01), and after hypotension (r2 = 0.555, P < 0.05). These results suggest that nicardipine may be a useful drug to treat intraoperative hypertension during cerebral aneurysm surgery. (Anesth Analg 1993;76:1227-33)

The Effect of Nicardipine on Carotid Blood Flow Velocity, Local Cerebral Blood Flow, and Carbon Dioxide Reactivity During Cerebral Aneurysm Surgery

We studied the effects of nicardipine (initial infusion rate 0.5 micrograms.kg-1 x min-1) on blood flow velocity in the internal carotid artery, local cerebral blood flow (LCBF), and carbon dioxide reactivity in 20 patients undergoing craniotomy for cerebral aneurysm clipping under isoflurane anesthesia. The blood flow velocity in the internal carotid artery was measured at T0 and T3 by a 20-MHz pulsed ultrasound Doppler flowmeter. LCBF was measured by the thermal gradient blood flow meter. Group A consisted of 10 patients with a good neurologic status (Hunt and Kosnik Grade I); Group B consisted of 10 patients with a poor status (Grades II-IV). Nicardipine was infused until the mean arterial blood pressure decreased to about 75% of the initial value and was maintained at this level until the completion of aneurysm clipping. The measurements of hemodynamics and LCBF were performed after the exposure of the internal carotid artery (T0), and 10 and 30 min after the start of nicardipine (T1 and T2, respectively), before aneurysm clipping (T3), and 30 min after its discontinuation (T4). Carbon dioxide reactivity [% ALCBF/APaCO2 (%/mm Hg)] was evaluated at T0, T3, and T4. Mean arterial blood pressure decreased after nicardipine infusion in both groups. LCBF did not change during nicardipine infusion in either group. Blood flow velocity increased significantly in Group A after nicardipine infusion from 45.1 +/- 6.9 to 51.5 +/- 6.4 cm/s (P < 0.05), but in Group B flow velocity did not change.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of intracoronary nitroglycerin administration on phasic pattern and transmural distribution of flow during coronary artery stenosis.

Nitroglycerin is effective in relieving myocardial ischemia; however, intracoronary nitroglycerin often fails to relieve angina and has been reported to have deleterious effects on subendocardial blood flow. To understand the mechanisms involved, we evaluated the direct effect of nitroglycerin on coronary circulation of the ischemic hearts. We measured the phasic pattern of intramyocardial coronary arterial flow with an 80-channel, 20-MHz pulsed Doppler ultrasound flowmeter under moderate to severe coronary artery stenosis (distal perfusion pressure approximately 45 mm Hg group 1, n = 6) and transmyocardial blood flow distribution using radioactive microspheres while maintaining coronary pressure at a low constant level (40 mm Hg, group 2, n = 6). In anesthetized open-chest dogs, the left main coronary artery was perfused directly from the right carotid or femoral artery. In this bypass circuit, pressure was controlled with an occluder or a reservoir was connected to the circuit. In group 1, the systolic and diastolic pressures distal to the stenosis decreased significantly after intracoronary administration of nitroglycerin at maximal coronary flow from 66.5 +/- 18.5 to 56.5 +/- 13.8 mm Hg (p less than 0.01) and from 36.6 +/- 14.4 to 27.5 +/- 8.9 mm Hg (p less than 0.01), respectively. The phasic pattern of the septal artery flow was predominantly diastolic and was characterized by systolic reverse flow even in the absence of stenosis. Coronary stenosis increased systolic reverse flow. Nitroglycerin increased diastolic forward flow (p less than 0.05) but augmented systolic reverse flow markedly (p less than 0.001). In group 2, nitroglycerin increased subepicardial flow (p less than 0.05) but failed to increase subendocardial flow. With the administration of nitroglycerin, the subendocardial-to-subepicardial flow ratio decreased significantly from 0.73 +/- 0.19 to 0.32 +/- 0.14 (p less than 0.01). The increased systolic reverse flow after intracoronary administration of nitroglycerin may be closely related to failure of subendocardial blood flow to increase with increase subepicardial flow.

Effects of Environmental Hyperthermia on Cardiovascular Function in the Rat Embryo

Effects of hyperthermia on the cardiovascular function of the mammalian embryo have not been well defined. The effect of hyperthermia on the blood flow and umbilical artery blood pressure was studied in rat embryos at gestational d 12 by using a method developed in our laboratory. When the temperature was changed from 37 to 42 degrees C, the heart rate increased by 15% (n = 33). Mean umbilical artery blood pressure, measured by a servo-null micropressure system, decreased from 0.64 +/- 0.05 to 0.53 +/- 0.04 mm Hg (n = 11), whereas blood flow velocity at the conotruncus, a measure of cardiac output, obtained by a 20-MHz pulsed Doppler ultrasound flowmeter, increased by 36 +/- 11% (n = 11). Mean umbilical artery blood flow increased by 66 +/- 13% (n = 11) and its vascular resistance, calculated by ratio analysis, decreased from 3.7 (median) to 1.8 units. These changes returned to baseline values when the temperature was returned to 37 degrees C. The change in blood pressure was different from that seen in the chick embryo, indicating that there is species difference in the hemodynamic effect.

Enhanced patency of small-diameter tubings after surface immobilization of heparin fragments. A study in the dog.

The luminal surfaces of polyethylene and polyurethane tubings of 1 mm inner diameter and 1 m in length were coated with heparin by end point attachment and thereafter sterilized in ethylene oxide. The tubings were inserted as arterio-venous shunts from the aorta to the superior caval vein via a carotid artery and a jugular vein. Patency was assessed with an ultrasound doppler flow meter and flow measurements. All nonheparinized shunts occluded within 10 days with a mean elapsed time from the insertion of the tubing is the last positive doppler registration being 3.5 days. The corresponding patency time for heparinized shunts was 25.9 days. The occlusion of the heparinized tubings was due to the incorporation of the ends of the tubings in the walls of aorta and caval vein, whereas the nonheparinized tubings occluded as a result of clot formation. It is concluded that surface immobilization of heparin with sequences capable of activating antithrombin may be beneficial in the development of small-diameter vascular protheses.

Vascularity in cutaneous melanoma detected by Doppler sonography and histology: Correlation with tumour behaviour

The blood flow in 71 primary skin melanomas was investigated by a 10MHz Doppler ultrasound flowmeter and flow signals were analysed on an Angioscan-II spectrum analyser. Doppler flow signals were detected in 44 tumours, with a close relationship to Breslow's tumour thickness. No blood flow signal was detected in 27 lesions and 25 of these had a tumour thickness of 0.8 mm or less. Ninety-seven per cent of tumours of thickness greater than 0.8 mm had detectable Doppler flow signals. Histological assessment of vascularity by Ulex europaeus agglutinin 1 lectin staining showed a high vascularity at the tumour base of Doppler positive lesions. The vascularity quantified by measurement on an IBAS-2 image analyser correlated well with the blood flow demonstrated by Doppler ultrasound. This study indicates the development of a neovascular bed as the tumour thickness approaches 0.8 mm. Doppler signal analysis revealed higher peak and mean systolic frequencies over melanomas associated with regional or systemic spread than flow signals from melanomas of patients remaining disease-free for 2 years.

Hemodynamic Effect of Percutaneous Transluminal Angioplasty for Lower Limb Atherosclerosis

Measurements of ankle pressure index (API) and arterial flow velocity including calculation of pulsatility index (PI) from the common femoral and pedal arteries were performed in 89 limbs of 75 patients before and after percutaneous transluminal angioplasty (PTA) (63 iliac and 26 femoropopliteal). A pulsed wave Doppler ultrasound flowmeter was used. An increase of API at rest of at least 0.15 or the absence of pressure drop after exercise following PTA was used as criteria for a hemodynamically successful angioplasty. In patients with hemodynamically successful PTA of an iliac obstruction PI increased from 4.2 to 8.6 (p less than 0.001); 91 per cent of these patients improved clinically. When iliac angioplasty was hemodynamically unsuccessful, PI remained unchanged; 11 per cent of these patients improved clinically. All limbs with hemodynamically successful PTA of a femoropopliteal obstruction improved clinically and PI increased from 3.1 to 8.7 (p less than 0.001). After hemodynamically unsuccessful femoropopliteal PTA, PI remained unchanged though 25 per cent of these patients improved clinically. These results illustrate that measurement of arterial flow velocity with calculation of PI may be a useful supplement for the functional evaluation of the effect of PTA, since symptomatic response alone may be unreliable.

Arterial blood flow in deep venous thrombosis of the lower limbs

Calf blood flow was measured in 19 patients with deep venous thrombosis (DVT) of the lower limb using a mercury strain gauge. The affected limb had a significantly (P less than 0.05) higher blood flow (2.9 +/- 1.4 ml/min. 100 g of tissue) then the contralateral limb (2.3 +/- 1.2 ml/min. 100 g). Blood flow velocity in the common femoral artery measured with a pulsed Doppler ultrasound flowmeter in 13 patients was also significantly (P less than 0.05) higher in the limb with DVT (6.6 +/- 2.8 cm/s) compared to the contralateral limb (5.3 +/- 3.0 cm/s). Interstitial fluid hydrostatic pressure (Pif) was measured by the "wick-in-needle" technique in the deep posterior compartment of the leg. There was a significant (P less than 0.001) increase in the limb with DVT (6.3 +/- 5.5 mmHg) compared to the contralateral limb (1.2 +/- 3.4 mmHg).

Doppler ultrasound surface monitoring of both arterial and venous flow in clinical free tissue transfers.

A hand-held nondirectional Doppler ultrasound flowmeter has been used to monitor the arterial and venous patency of 60 clinical free tissue transfers. Based on information obtained, three flaps were re-explored, at which time the preoperative diagnosis of arterial or venous occlusion was confirmed. Two of the three flaps were salvaged. This readily available, noninvasive system has been useful in monitoring clinical free tissue transfers whose surfaces are exposed.

Monitoring microvascular anastomoses by spectral analyzing multifrequency bidirectional CW ultrasound Doppler flowmeter.

A new technique is presented for monitoring microvascular free tissue transfer. When performing free myocutaneous latissimus dorsi flap transfer to the lower limb, the flap artery and vein often lie on top of each other. Using conventional CW or pulsed ultrasound Doppler flowmeters, it is impossible to examine the patency of arterial and venous anastomoses simultaneously. However, a bidirectional CW ultrasound Doppler system and its spectral analyzing display can simultaneously examine both anastomoses, by separating arterial inflow from venous backflow multifrequencies.