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Arterial Flow (arterial + flow)

Distribution by Scientific Domains

Medical Sciences	93%

Kinds of Arterial Flow

hepatic arterial flow

Selected Abstracts

Hepatic arterial flow becomes the primary supply of sinusoids following partial portal vein ligation in rats

JOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 10 2006
Yukihiro Yokoyama
Abstract Background and Aim:, Partial portal vein ligation (PPVL) is a commonly used procedure to induce prehepatic portal hypertension in animal models. The aim of this study was to test the hypothesis that the hepatic arterial flow becomes the primary source feeding the sinusoids in the liver after PPVL. Methods:, Sprague,Dawley rats underwent either sham operation or partial portal vein ligation (PPVL). The number of vessels in the liver at 2 weeks postoperatively was determined by factor VIII immunolocalization and the gene expression of angiogenic factors was assessed by RT-PCR. The total hepatic arterial supply to the liver was measured using the fluorescent microsphere injection technique. To further test the hypothesis, two additional groups of rats underwent hepatic artery ligation (HAL) or PPVL plus HAL (PPHAL). The integrity of hepatic microcirculation was then evaluated in all four groups by intravital microscopy. Results:, At 2 weeks after operation, the number of vessels detected by factor VIII staining was significantly higher in PPVL compared to sham. Densitometric analysis of RT-PCR bands revealed a significant increase of vascular endothelial growth factor gene expression in PPVL compared to sham. Arterial flow to the liver measured by fluorescent microspheres was increased by 190% in PPVL compared to sham. When all four groups were compared, no prominent histological abnormality was observed in sham, HAL, and PPVL groups; however, PPHAL livers showed focal necrosis and inflammatory cell infiltration around the portal triads. Additionally, only the PPHAL livers showed a decreased sinusoidal diameter and significantly lower perfusion index (PPHAL 42.9 ± 6.1; sham 85.7 ± 7.0, PPVL 80.2 ± 6.5, HAL 70.9 ± 4.5). Conclusions:, These results suggest that the hepatic artery flow becomes the primary source for the blood supply of sinusoids and the compensatory change in the hepatic arterial system plays a critical role in maintaining microcirculatory perfusion following the restriction of the portal vein flow by PPVL. [source]

Effect of Hepatic Artery Flow on Bile Secretory Function After Cold Ischemia

AMERICAN JOURNAL OF TRANSPLANTATION, Issue 2 2003
David P. Foley
These studies evaluated the influence of hepatic arterial flow on biliary secretion after cold ischemia. Preparation of livers for transplantation or hepatic support impairs biliary secretion. The earliest indication of cold preservation injury during reperfusion is circulatory function. Arterial flow at this time may be critical for bile secretion. Porcine livers were isolated, maintained at 4° for 2 h and connected in an extracorporeal circuit to an anesthetized normal pig. The extracorporeal livers were perfused either by both the hepatic artery and portal vein (dual) or by the portal vein alone (single). Incremental doses of sodium taurocholate were infused into the portal vein of both the dual and single perfused livers, and the bile secretion was compared. Most endogenous bile acids are lost during hepatic isolation. After supplementation, the biliary secretion of phosphatidyl choline and cholesterol was significantly better in the dual than single vessel-perfused livers; however, no difference was seen in bilirubin output. Single perfused livers were completely unable to increase biliary cholesterol in response to bile acid. The dependence of bile cholesterol secretion on arterial flow indicates the importance of this flow to the detoxification of compounds dependent on phosphatidyl choline transport during early transplantation. [source]

Numerical modelling of the pressure wave propagation in the arterial flow

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 6-7 2003
Giuseppe Pontrelli
Abstract A differential model of blood flow through an arterial vessel is presented. It consists of a one-dimensional model describing the non-linear fluid,wall interaction coupled with a simple lumped parameter model which accounts for outlet boundary conditions. The model includes a local stiffening of the vessel and the wave propagation of disturbances due to prosthetic implantations is also studied. The non-linear problem is solved by a finite-difference method on a staggered grid and some numerical simulations are analysed and discussed. Copyright © 2003 John Wiley & Sons, Ltd. [source]

Doppler studies of the ovarian venous blood flow in the diagnosis of adnexal torsion

JOURNAL OF CLINICAL ULTRASOUND, Issue 8 2009
Khatib Nizar MD
Abstract Purpose. To evaluate the role of ovarian Doppler studies in diagnosing adnexal torsion. Methods. We included in that study all patients who had an adnexal mass with clinical symptoms of intermittent lower abdominal pain and were hospitalized for at least 48 hours of observation. Our protocol included: measurements of the size of the adnexal mass, presence or absence of ovarian edema, presence or absence of adnexal vascularity, presence or absence of ovarian artery flow, presence or absence of ovarian venous flow, pattern of ovarian venous flow. The ovarian artery and vein were sampled just above and lateral to the adnexa. Sensitivity, specificity, and positive and negative predictive values in the diagnosis of adnexal torsion were calculated for each of the gray-scale and Doppler sonographic (US) findings. Results. One hundred and ninety-nine patients presented with adnexal mass and intermittent lower abdominal pain. Sensitivity and specificity of tissue edema, absence of intra-ovarian vascularity, absence of arterial flow, and absence or abnormal venous flow in the diagnosis of adnexal torsion were: 21% and 100%, 52% and 91%, 76% and 99%, and 100% and 97%, respectively. All patients with adnexal torsion had absent flow or abnormal flow pattern in the ovarian vein. In 13 patients, the only abnormality was absent or abnormal ovarian venous flow with normal gray-scale US appearance and normal arterial blood flow. Of these 13 patients, 8 (62%) had adnexal torsion or subtorsion. Conclusion. Abnormal ovarian venous flow may be the only abnormal US sign observed during the early stage of adnexal torsion. © 2009 Wiley Periodicals, Inc. J Clin Ultrasound 2009 [source]

Color Doppler sonography of hepatic artery reconstruction in liver transplantation

JOURNAL OF CLINICAL ULTRASOUND, Issue 1 2002
Alessandro De Candia MD
Abstract Purpose The purpose of this study was to evaluate the Doppler spectral waveforms in the hepatic artery after liver transplantation and hepatic artery reconstruction by end-to-end anastomosis or aortohepatic bypass. The peak systolic velocities (PSVs), end-diastolic velocities (EDVs), and resistance indices (RIs) between the 2 reconstruction groups were compared to establish normal post-transplantation values. Methods We retrospectively reviewed the Doppler sonograms and the sonographic reports from 48 patients who had undergone liver transplantation, 30 with end-to-end arterial anastomoses and 18 with aortohepatic bypasses. All aortohepatic bypasses had been performed using the infrarenal technique. All sonographic examinations had been performed 3,6 months after transplantation in patients with no clinical sign of transplant failure and whose liver function test results more normal. We compared the mean hepatic artery PSVs, EDVs, and RIs of the 2 groups. Results Doppler spectral analysis allowed the detection of 2 types of arterial flow, a low-resistance pattern in the end-to-end anastomosis group and a high-resistance pattern with low diastolic flow in the infrarenal bypass group. The mean PSV ± standard deviation (SD) was 57 ± 16 seconds in the end-to-end anastomosis group and 62 ± 16 cm/second in the infrarenal bypass group. The mean EDV ± SD was 25 ± 14 cm/second in the end-to-end anastomosis group and 12 ± 4 cm/second in the infrarenal bypass group. The RIs ranged from 0.33 to 0.71 (mean ± SD, 0.58 ± 0.13) in the patients with end-to-end anastomoses and from 0.70 to 0.87 (mean ± SD, 0.77 ± 0.06) in those with infrarenal bypasses. The difference in the mean RIs between the 2 groups was statistically significant (p < 0.05). Conclusions Spectral waveform and RI are associated with the length and caliber of the type of hepatic artery anastomosis used. End-to-end anastomoses are short and have a uniform small caliber; aortohepatic bypasses are longer and have a progressively by smaller caliber. We must be cognizant of the method of anastomosis used when examining patients for complications after liver transplantation because the method used affects the resulting spectral waveform and RI. © 2002 John Wiley & Sons, Inc. J Clin Ultrasound 30:12,17, 2002. [source]

Hepatic arterial flow becomes the primary supply of sinusoids following partial portal vein ligation in rats

Ulnar Artery as Access Site for Cardiac Catheterization: Anatomical Considerations

JOURNAL OF INTERVENTIONAL CARDIOLOGY, Issue 1 2008
DOBRIN VASSILEV M.D.
Transradial approach to coronary angiography and angioplasty has been widely accepted in the last few years. As an alternative approach from the forearm, with some potential advantages, we decided to test the transulnar approach as a first-choice strategy. Methods and Results: Transulnar approach was tried in 131 patients. In 29 patients there was no palpable ulnar artery or Allen test was negative. From the remaining 92 patients we performed successful coronary angiography and angioplasties in 59 patients (64% success rate in those who had palpable artery). The most frequent reason for access site failure (54.5% of all failed procedures) was inability to introduce wire despite good arterial flow. We found that the ulnar artery was not the largest artery of the forearm (mean diameter 2.76 ± 0.08 mm compared with radial artery 3.11 ± 0.12 mm) and had relatively frequent anatomical anomalies,11.9%. There were no major local complications, with very few minor complications. Spasm frequency was 13.6%, which is higher than that reported for transradial studies. Conclusions: Transulnar artery approach is feasible for cardiac catheterization: however, it has higher access site failure rates in an unselected patient population. It could be used as an alternative option in selected patients, but operators must be prepared to overcome frequent anatomical anomalies and spasm. [source]

Magnetic resonance angiography of collateral vessels in a murine femoral artery ligation model

NMR IN BIOMEDICINE, Issue 1 2004
Shawn Wagner
Abstract The in vivo detection of growing collateral vessels following arterial occlusion is difficult in small animals. We have addressed the feasibility of performing high resolution time-of-flight angiograms to monitor the growth of collateral vessels after femoral artery occlusion in mice. We will also present a low-pass quadrature birdcage coil construction with a sufficient signal-to-noise ratio to produce high resolution. After a 4-month recovery period a C57BL/6 mouse with a surgical occlusion of the right femoral artery was used to assess the image quality and time requirements to produce magnetic resonance angiograms sufficient to assess collateral artery development using a two-dimensional gradient echo sequence. At a resolution of 100,×,100,×,100,,m and a matrix size of 256,×,128,×,256 for a 2.56,cm isometric volume, three scans were performed with one, two and four repetitions resulting in signal-to-noise ratios for the femoral artery proximal to the ligation site of 58, 126 and 194, respectively. Five C57BL/6 mice were additionally measured 4 weeks after occlusion using two repetitions and the visual collateral vessels were assessed for number and location: 2.0,±,1.2 in quadriceps muscle, 0.6,±,0.5 in adductor (deep adductor vessel), 0.0,±,0.0 in adductor (surface adductor vessels). The results showed a significant difference, two-sided t -test, p,<,0.05, in number of vessels in all the locations. We have shown that this method can be utilized to elucidate the contribution of collateral vessels to arterial flow. Copyright © 2004 John Wiley & Sons, Ltd. [source]

Recurrence of hepatic artery thrombosis following acute tacrolimus overdose in pediatric liver transplant recipient

PEDIATRIC TRANSPLANTATION, Issue 6 2005
Soshi Takahashi
Abstract:, Acute overdose of tacrolimus appears to cause no or minimal adverse clinical consequences. We encountered a pediatric case who underwent liver transplantation associated with hepatic artery thrombosis (HAT), which recurred following acute tacrolimus overdose. A 10-month-old girl underwent living-related liver transplantation because of biliary atresia. To reconstruct the hepatic artery, the right gastroepiploic artery of the donor was interposed between the right hepatic artery of the recipient (2.5 mm in diameter) and the left hepatic graft artery (1 mm in diameter) under microscopy. On postoperative day 4, Doppler ultrasonography showed a remarkable reduction in hepatic arterial flow, which was consistent with HAT. The patient underwent immediate hepatic arteriography and balloon angioplasty. The stenotic sites were dilated by the procedure. Tacrolimus was infused intravenously after transplantation and the infusion rate was adjusted to achieve a target concentration of 18,22 ng/mL, which remained stable until the morning of day 6. An unexpectedly high blood concentration of tacrolimus (57.4 ng/mL) was detected at 6:00 pm on day 6, and tacrolimus was discontinued at 9:00 pm; however, the tacrolimus level reached 119.5 ng/mL at 0:00 h on day 7. While the concentration decreased to 55.2 ng/mL on the morning of day 7, the hepatic arterial flow could not be observed by Doppler ultrasonography. Emergent hepatic arteriography showed stenosis of the artery at the proximal site of the anastomosis. Balloon angioplasty was again performed and the stenotic site was successfully dilated. High level of tacrolimus exposure to the hepatic artery with injured endothelium by preceding angioplasty may have been related to the recurrence of HAT in the present case. [source]

Effect of Hepatic Artery Flow on Bile Secretory Function After Cold Ischemia

Changes in peak systolic velocity induced by chronic therapy with phosphodiesterase type-5 inhibitor

ANDROLOGIA, Issue 3 2006
M. C. Sighinolfi
Summary The aim of this study was to assess the influence of chronic therapy with phosphodiesterase type-5 inhibitor on penile haemodynamics at colour Doppler ultrasound. Thirty patients affected by erectile dysfunction (ED) of different aetiology tested with the International Index of Erectile Function (IIEF-5) were evaluated with penile colour Doppler ultrasound during basic and dynamic phases (10 ,g PGE1) before and after chronic self-administration of sildenafil citrate (dosage: 100 mg as required, two to three times a week) for a period of 5,20 months (mean: 12.3). Treatment was interrupted 14,21 days before the second ultrasound evaluation. Peak systolic velocity (PSV) and end-diastolic velocity (EDV) were recorded by means of colour Doppler; cut off values were 25 and 5 cm s,1 respectively. Data were compared by nonparametric tests. Twenty-two of the 30 patients showed normal pre-treatment PSV, while eight of 30 had an insufficient arterial flow. Mean pre-treatment EDV was 4.7 ± 0.5. After chronic therapy with sildenafil, a global improvement of 10.5% on PSV was seen (P < 0.001), without any statistical difference between patients with normal pre-treatment peak and those with a borderline one. No statistically significant changes were found for EDV (P = 0.98). It is concluded that chronic therapy with phosphodiesterase-5 inhibitor results in a significant improvement in PSV values, probably due to a penile chronic vasoactive enhancement. [source]

Development of the Baylor Gyro Permanently Implantable Centrifugal Blood Pump as a Biventricular Assist Device

ARTIFICIAL ORGANS, Issue 9 2001
Kenji Nonaka
Abstract: The Baylor Gyro permanently implantable centrifugal blood pump (Gyro PI pump) has been under development since 1995 at Baylor College of Medicine. Excellent results were achieved as a left ventricular assist device (LVAD) with survival up to 284 days. Based on these results, we are now focusing on the development of a biventricular assist device (BVAD) system, which requires 2 pumps to be implanted simultaneously in the preperitoneal space. Our hypothesis was that the Gyro PI pump would be an appropriate device for an implantable BVAD system. The Gyro PI 700 pump is fabricated from titanium alloy and has a 25 ml priming volume, pump weight of 204 g, height of 45 mm, and pump diameter of 65 mm. This pump can provide 5 L/min against 100 mm Hg at 2,000 rpm. In this study, 6 half-Dexter healthy calves have been used as the experimental model. The right pump was applied between the infundibular of the right ventricle and the main pulmonary artery. The left pump was applied between the apex of the left ventricle and the thoracic descending aorta. As for anticoagulation, heparin was administered at the first postoperative week and then converted to warfarin sodium from the second week after surgery. Both pump flow rates were controlled maintaining a pulmonary arterial flow of less than 160 ml/kg/min for the sake of avoidance of pulmonary congestion. Blood sampling was done to assess visceral organ function, and the data regarding pump performance were collected. After encountering the endpoint, which the study could not keep for any reasons, necropsy and histopathological examinations were performed. The first 2 cases were terminated within 1 week. Deterioration of the pump flow due to suction phenomenon was recognized in both cases. To avoid the suction phenomenon, a flexible conduit attached on the inlet conduit was designed and implanted. After using the flexible inflow conduit, the required power and the rotational speed were reduced. Furthermore, the suction phenomenon was not observed except for 1 case. There was no deterioration regarding visceral organ function, and pulmonary function was maintained within normal range except for 1 case. Even though the experimental animal survived up to 45 days with the flexible inflow conduit, an increase in power consumption due to thrombus formation behind the impeller became a problem. Lower rotational speed, which was probably produced by the effectiveness of the flexible inflow conduit, was speculated to be one of the reasons. And the minimum range of rotational speed was 1,950 rpm in these 6 BVAD cases and the previous 3 cases of LVAD. In conclusion, 6 cases of BVAD implantation were performed as in vivo animal studies and were observed up to 45 days. The flexible inflow conduit was applied in 4 of 6 cases, and it was effective in avoiding a suction phenomenon. The proper rotational speed of the Gyro PI 700 pump was detected from the viewpoint of antithrombogenicity, which is more than 1,950 rpm. [source]

External cephalic version induced fetal cerebral and umbilical blood flow changes are related to the amount of pressure exerted

BJOG : AN INTERNATIONAL JOURNAL OF OBSTETRICS & GYNAECOLOGY, Issue 5 2004
Tak Yeung Leung
Objective To correlate the applied pressure during external cephalic version with the changes in fetal middle cerebral arterial and umbilical arterial flow before and after the procedure. Design A prospective observational study over a two-year period. Setting External cephalic version was performed in a university hospital. Population Sixty-nine women with singleton breech-presenting pregnancy at or above 36 weeks of gestation undergoing external cephalic version. Methods During external cephalic version, the operator wore a pair of pressure-sensing gloves which had thin piezo-resistive sensors positioned on the palmar surface. During each version procedure, real-time pressure readings were recorded from all sensors, and then analysed with a computer program. The amount of pressure applied over time was presented by pressure,time integral. The pulsatility indices of both fetal middle cerebral artery and umbilical artery before and after external cephalic version were measured. The changes of pulsatility indices of both middle cerebral artery and umbilical artery were presented as a ratio of the post-external cephalic version pulsatility indices to pre-external cephalic version pulsatility indices, denoted by middle cerebral artery pulsatility index ratio and umbilical artery pulsatility index ratio, respectively. The statistical correlation between pressure,time integral and middle cerebral artery pulsatility index ratio and umbilical artery pulsatility index ratio are analysed using Pearson's correlation test. Main outcome measures Changes in pulsatility indices of fetal middle cerebral and umbilical arteries and fetal heart rate after external cephalic version. Results The overall success rate of external cephalic version was 77%. There was a significant negative correlation between pressure,time integral and both middle cerebral artery pulsatility index ratio (P= 0.001) and umbilical artery pulsatility index ratio (P= 0.012). When women were categorised according to placental site, pressure,time integral was negatively correlated with middle cerebral artery pulsatility index ratio only when the placenta was posteriorly located (P= 0.003), and with umbilical artery pulsatility index ratio only when the placenta was laterally located (P= 0.03). Conclusions The greater the force applied during external cephalic version, the greater the reduction in pulsatility indices of middle cerebral artery and umbilical artery, indicating an increase in blood flow through these arteries. The increase in cerebral blood flow after external cephalic version is more prominent when the placenta is lying posteriorly, while the increase in umbilical flow is more prominent when the placenta is lying laterally. These findings suggest that the vascular changes probably represent a direct effect of force exerted on the fetal head and the placenta. [source]

Staged in situ bypass

BRITISH JOURNAL OF SURGERY (NOW INCLUDES EUROPEAN JOURNAL OF SURGERY), Issue 4 2000
T. A. Ojimba
Background: After femoral revascularization, following embolectomy or proximal reconstruction, the need for additional distal revascularization may be unpredictable. This dilemma may be addressed by anastomosing the detached upper end of the long saphenous vein to the femoral arteriotomy, as for in situ bypass, permitting some outflow into proximal vein tributaries. Later, if ischaemia persists, distal arterial flow can be established by closed retrograde saphenous valvulotomy. Methods: Over 12 years this technique was employed in 26 legs in 22 patients, following inflow reconstruction in 15 and femoral embolectomy in seven. Postoperative observation showed persisting distal ischaemia in 14 legs and distal bypass was completed after 1,9 days, using local anaesthesia without femoral re-exposure. One patient died at 15 days and 13 grafts were patent on discharge from hospital. Results: In 12 legs in 11 patients, limb perfusion was deemed adequate after operation. Four patients (five legs) died in hospital and seven were discharged. No further procedure was required in five and the proximal long saphenous vein presumably thrombosed. In two legs the whole long saphenous system had become pulsatile at 7 and 8 months, and a distal bypass was completed. No amputations were required in this series. Conclusion: Staged in situ bypass can avoid prolonged and complex reconstructions in frail patients and facilitates the use of local anaesthesia, where necessary. © 2000 British Journal of Surgery Society Ltd [source]