Superior mesenteric artery blood flow velocity and estimated volume flow: duplex Doppler US study of preterm and term neonates

To obtain information about intestinal hemodynamics of healthy neonates, the authors assessed velocity and volume of blood flow with duplex Doppler sonography in the superior mesenteric artery (SMA) in 91 stable preterm and term neonates. Blood flow velocity in the SMA and estimated volume blood flow increased linearly with gestational age and increasing body weight. The mean estimated volume blood flow (+/- standard deviation) was 43 mL/kg/min +/- 13 and did not depend on differences in body weight. The authors also assessed blood flow velocity in the SMA and volume blood flow in 18 infants with conditions that may affect blood supply to the bowel. Twelve infants who were small for gestational age appeared to have an abnormally low resistance of the vascular bed of the SMA during the 1st days of life, as compared with stable appropriate-for-gestational-age infants matched for gestational age. Three of six term neonates with cardiovascular abnormalities had left ventricular outflow obstruction and an abnormal blood flow velocity waveform of the SMA, suggesting a decrease in blood supply to the bowel. The results of this study may help in evaluations of intestinal perfusion in infants with abnormal conditions.     

Sexual impotence caused by vascular disease: diagnosis with duplex sonography

We used duplex Doppler sonography to assess the hemodynamic function of the penis in patients with impotence to determine if there is arterial disease or if the veins are incompetent. The penis was scanned in the flaccid state, then again after erection was induced by intracorporal injection of papaverine. The diameter of each cavernosal artery was measured before and after injection and, by using Doppler sonography, the maximal systolic velocity in each cavernosal artery was measured. The Doppler gate was placed over the dorsal vein to detect any flow in that vein signifying venous leakage. The Doppler gate then was placed over the cavernosal veins in an attempt to detect cavernosal venous incompetence. Forty-five men with impotence were included in the study. In 39 patients, the cause of impotence was confirmed by other studies. The diameter of the cavernosal arteries and the increase in diameter of these arteries after induction of an erection were similar in all diagnostic groups. The peak systolic velocity, however, was decreased in patients with arterial insufficiency as compared with the velocity in normal subjects. In normal subjects, the mean peak velocity was 47 +/- 9 cm/sec; in patients with mild to moderate arterial insufficiency it was 35 +/- 16 cm/sec; in patients with severe arterial insufficiency it was 7 +/- 8 cm/sec. The difference in peak velocities between the right and left cavernosal arteries after papaverine injection (asymmetric arterial response) was significantly larger in patients with mild to moderate arterial insufficiency than in other diagnostic groups. Four patients with venous incompetence had detectable flow in the dorsal vein, but no flow could be detected with Doppler sonography in the cavernosal veins in any patients, including those who were proved to have significant cavernosal venous leaks. Our findings suggest that Doppler measurement of maximal systolic velocity in the cavernosal arteries after papaverine injection is an accurate indicator of arterial function. Asymmetric flow in the cavernosal arteries also suggests some degree of arterial insufficiency. Diameters of the cavernosal arteries and their increase after injection are not predictive of arterial patency. Doppler sonography cannot show cavernosal venous leakage, but in some cases it can show dorsal venous incompetence.     

Assessment of coronary flow reserve with fast cine phase contrast magnetic resonance imaging: comparison with measurement by Doppler guide wire.

Fast cine phase contrast magnetic resonance imaging (fast cine phase contrast MRI) can measure phasic coronary flow velocity in humans. The purpose of this study was to compare the coronary flow velocity reserves measured by MR IMAGING with those obtained by Doppler guide wire. Nineteen patients with ischemic or valvular heart disease were studied. Fast cine phase contrast MR images of the left anterior descending (LAD) artery were acquired during breath-hold time in the basal state and after administration of dipyridamole. Flow velocity in the LAD artery was also measured with Doppler guide wire before and after venous injection of dipyridamole in all subjects. Flow velocity in the coronary artery measured with MR IMAGING in the basal state (12.5 +/- 4.9 cm/sec) was significantly lower than that obtained with Doppler guide wire (32.4 +/- 12.1 cm/sec, P < 0.01). However, MR assessments of coronary flow velocity reserve showed a good linear correlation with those measured by Doppler guide wire (r = 0.91). In conclusion, fast cine phase contrast MR imaging is a useful technique, which can provide a noninvasive assessment of flow reserve ratios in patients with coronary artery disease. J. Magn. Reson. Imaging 1999;10:563-568.     

Comparison of vertebral artery velocity and flow volume measurements for diagnosis of vertebrobasilar insufficiency using color duplex sonography

INTRODUCTION: The aim of this study was to compare the measurements of vertebral artery (VA) systolic flow velocity and flow volume for diagnosis of vertebrobasilar insufficiency (VBI). MATERIAL AND METHODS: We examined 96 patients who were referred for evaluation of VBI. Net vertebral artery flow volume and mean systolic flow velocity were determined by using color duplex sonography. We had grouped the patients into three according to VA flow volume: group 1 was consisted of patients with severely damped VA flow volume (lower than 120 mL/min), group 2 was consisted of patients with moderately damped VA flow volume (120-200 mL/min), group 3 was consisted of patients with normal VA flow volume (>200 mL/min). The mean systolic flow velocities in each group were compared by one-way ANOVA. RESULTS: Mean VA systolic flow velocities of groups 1, 2 and 3 were 32 +/- 12, 42 +/- 10 and 46 +/- 8 cm/s, respectively. Mean VA systolic flow velocity in group 1 was significantly lower than that of group 2 (P = 0.001). However, there were no significant differences between VA systolic flow velocities in groups 2 and 3 (P = 0.2). CONCLUSIONS: According to our findings, measurement of volume in addition to velocity is more valuable in detection of moderately damped VA flow volumes in diagnosis of VBI.     

Ultrasonographically predicting the extent of collateral flow through superficial temporal artery-to-middle cerebral artery anastomosis

BACKGROUND AND PURPOSE: This study was performed to elucidate whether the extent of bypass flow through superficial temporal artery-to-middle cerebral artery (STA-MCA) anastomosis could be indirectly estimated by measuring the blood flow velocity in the superficial temporal artery (STA) by using duplex ultrasonography. METHODS: We analyzed 29 patients (31 sides) who underwent STA-MCA bypass surgery for occlusive cerebrovascular disease (28 sides) or unclippable cerebral aneurysm that required therapeutic occlusion of the internal carotid artery (three sides). The flow velocities of the STA were measured by using ultrasonography. For patients who underwent the surgery unilaterally, the flow velocity ratios of the operated side to the contralateral side for the individual arteries were calculated. The correlation between these flow velocity parameters and the extent of bypass flow, which was graded based on the findings of cerebral angiography, was investigated. RESULTS: Both the affected STA flow velocity and the STA flow velocity ratio, particularly those in the end diastole, increased in patients with more extensive bypass flow. In patients with extensive, moderate, and poor bypass flow, the end diastolic flow velocities of the operated STA were 27.4 +/- 8.8, 23.0 +/- 7.8, and 13.5 +/- 7.5 cm/s, respectively and the end diastolic flow velocity ratios of the STA were 3.4 +/- 0.8, 2.1 +/- 0.5 and 1.3 +/- 0.4, respectively. The pulsatility index and resistance index of the affected STA were significantly lower in the patients with more extensive bypass flow. The optimal threshold value of the end diastolic flow velocity ratio of STA for the group with extensive bypass flow was 2.75, whereas that for the group with poor bypass flow was 1.60. With the obtained values, the sensitivity and specificity were 87.5% and 93.9% for the group with extensive bypass flow and 95.2% and 95.0% for the group with poor bypass flow, respectively. CONCLUSION: The blood flow velocity in the operated STA seems to be a highly sensitive parameter for predicting the extent of bypass flow in patients undergoing STA-MCA anastomosis.     

Sonographic assessment of splanchnic arteries and the bowel wall

The intestinal wall can be visualized using high resolution transabdominal ultrasound. The normal intestinal wall thickness in the terminal ileum, cecum, and right and left colon is <2mm when examined with graded compression. It is important to appreciate that a contracted intestinal segment can be misinterpreted as a thickened wall. Vascularisation can be mainly displayed in the second hyperechoic layer (submucosal layer) as well as vessels penetrating the muscularis propria. Imaging of the gastrointestinal wall is dependent on the experience of the examiner as well dependent on the equipment used. Acute or chronic inflammation of the intestinal wall is accompanied by increased perfusion of the mesentery, which can be displayed non-quantitatively with colour duplex. In contrast, ischemia is characterised by hypoperfusion of the mesenteric arteries and the bowel wall. The most promising sonographic approach in assessing splanchnic arteries and the bowel wall is combining the analysis of superior and inferior mesenteric inflow by pulsed Doppler scanning (systolic and diastolic velocities, resistance index) with the end-organ vascularity by colour Doppler imaging diminishing the influence of examination technique only displaying bowel wall vascularity. Colour Doppler imaging has been described as helpful in a variety of gastrointestinal disorders, particularly in patients with Crohn's disease, celiac disease, mesenteric artery stenosis and other ischemic gastrointestinal diseases, graft versus host disease and hemorrhagic segmental colitis.     

Characterization of arteriovenous malformation feeding vessels by carbon dioxide reactivity.

PURPOSETo characterize cerebral hemodynamics in patients immediately before microsurgical resection of moderate to large arteriovenous malformations during isoflurane anesthesia.METHODSIn angiographically defined arteriovenous malformation feeding and nonfeeding arteries, transcranial Doppler studies were performed in 25 surgeries on 22 patients. The mean blood flow velocity and pulsatility index were recorded in the middle, anterior, and posterior cerebral arteries. Transcranial Doppler velocities were measured at end-tidal carbon dioxide tensions (PetCO2) of about 25 and 35 mm Hg. Carbon dioxide reactivity was calculated as percentage mean blood flow velocity change per mm Hg PetCO2 change.RESULTSPatient demographic and clinical data for the arteriovenous malformation group followed the expected strata of a large arteriovenous malformation population. All patients were neurologically stable before surgery. A total of 43 feeding arteries and 55 nonfeeding arteries were studied. Compared with nonfeeders, feeders exhibited higher mean blood flow velocity (68 +/- 5 vs 31 +/- 3 cm/sec, P < 0.0001) and lower pulsatility index (0.64 +/- 0.03 vs 0.88 +/- 0.04, P < 0.001); anterior and middle cerebral artery velocities at normo- and hypocapnia were significantly higher than posterior cerebral arteries for both feeders and nonfeeders (P < 0.001). Carbon dioxide reactivity was 0.2 +/- 0.2%/mm Hg in feeders and 2.1 +/- 0.2%/mm Hg in nonfeeders, with no significant difference between arteries. In four of eight patients with lesions fed by the anterior circulation (middle cerebral artery with or without anterior cerebral artery feeders), posterior cerebral artery nonfeeders exhibited low reactivity. In 2 of 5 patients with ipsilateral posterior cerebral artery feeders, contralateral posterior cerebral artery nonfeeders exhibited impaired reactivity.CONCLUSIONSQuantitative transcranial Doppler studies are technically feasible in the operating room or interventional suite during anesthesia. Hemodynamic assessment using physiologic challenges of arteriovenous malformation feeders as well as angiographically uninvolved vessels may be useful as criteria in the assessment of malformations and arteriovenous malformation patients may exhibit abnormal vasoreactivity in distant uninvolved perfusion territories, suggesting a deranged neural control mechanism.     

Flow profiles in the left anterior descending and the right coronary artery assessed by MR velocity quantification: effects of through-plane and in-plane motion of the heart.

PURPOSE: The purpose of this work was to compare the temporal profiles of volume flow in the left anterior descending artery (LAD) and the right coronary artery (RCA) and to assess the effect of through-plane and in-plane myocardial motion. METHOD: In eight healthy volunteers, MR phase-difference velocity quantification was applied with prospective ECG triggering, pixel size of 1.16 x 0.98 mm2 (LAD) or 1.25 x 0.98 mm2 (RCA), velocity sensitivity of 40 cm/s, and data acquisition time window of 64 ms for LAD (3 ky lines per heartbeat) and 24 ms for RCA. In-plane motion was measured from the magnitude images. RESULTS: In the LAD, systolic peak and mean flow values were 0.94+/-0.28 and 0.30 +/-0.22 ml/s, respectively. Diastolic peak and mean flows were 2.42+/-0.56 and 1.38+/-0.43 ml/s. The systolic to diastolic ratio was 0.37+/-0.12 for peak flow and 0.22+/-0.15 for mean flow. Mean flow through the cardiac cycle was 59.1+/-15.0 ml/min. In the RCA, systolic peak and mean flow values were 1.96+/-0.69 and 0.74+/-0.31 ml/s, respectively. Diastolic peak and mean flows were 1.80+/-0.53 and 0.83+/-0.20 ml/s. The systolic to diastolic ratio was 0.97+/-0.58 for peak flow and 0.85+/-0.39 for mean flow. Mean flow through the cardiac cycle was 38.4+/-10.8 ml/min. The in-plane velocity of the coronary artery cross-section was 6.4+/-1.8 cm/s for the LAD and 14.9 +/-4.0 cm/s for the RCA (given by peak values in diastole). CONCLUSION: It is confirmed noninvasively with MR that the LAD shows a predominantly diastolic flow, whereas the RCA shows about equal flow values in systole and diastole. Through-plane motion correction is required for assessing the true flow patterns. The in-plane velocities of the coronary artery cross-sections imply a maximum data acquisition time window, estimated at 58 ms for the LAD and at 23 ms for the RCA.     

Superselective microcoil embolization of colonic hemorrhage

OBJECTIVE: We evaluated therapeutic microcoil embolization in a group of patients with severe colonic hemorrhage. MATERIALS AND METHODS: Twenty-seven patients with severe colonic bleeding due to diverticular disease (n = 19), angiodysplasia (n = 6), cecal ulcer (n = 1), or unknown cause (n = 1) underwent attempted microcoil embolization (n = 25). Microcatheters were used in all procedures, and embolization was performed at the level of the vasa recta or the marginal artery of Drummond. Branches of the superior mesenteric artery were embolized in 12 patients, branches of the inferior mesenteric artery were embolized in 12 patients, and branches of both the superior and inferior mesenteric arteries were embolized in one patient. RESULTS: Technical success was achieved in 93% (25/27) of the procedures. However, immediate hemostasis occurred in 96% (26/27) of patients because in one failed procedure, an occlusive dissection of the inferior mesenteric artery arrested bleeding. Three patients rebled within 24 hr. One patient was treated with endoscopic cauterization, and two patients underwent right hemicolectomy. One patient who underwent right hemicolectomy for rebleeding had ischemic changes found on pathologic analysis of the resected specimen, and a second patient who underwent embolization of branches of the superior and inferior mesenteric arteries developed bowel infarction requiring left hemicolectomy. Prolonged clinical success occurred in 81% (22/27) of patients. CONCLUSION: Therapeutic microcoil embolization for severe colonic hemorrhage is an effective and well-tolerated procedure.     

Doppler ultrasonography evaluation of paraumbilical vein and portal hypertension

Portal hypertension is associated to the development of portosystemic collateral veins, particularly the paraumbilical vein. PURPOSE: To evaluate the biometric and hemodynamic characteristics of the portal vessels related to the presence of a patent paraumbilical vein, in the setting of portal hypertension secondary to hepatosplenic schistosomiasis. METHODS: 75 patients with portal hypertension secondary to hepatosplenic schistosomiasis were evaluated by Doppler US. The patients were studied based on the presence (group B) or not (Group A) of a patent paraumbilical vein. The diameter and blood flow velocity of the portal vessels and of the paraumbilical vein were recorded. RESULTS: The paraumbilical vein was detected in 17.33% of patients. The results showed an increase of the diameter of the main and left portal vessels whenever a patent paraumbilical vein was present (portal vein: A = 1.14 +/- 0.29 cm/B = 1.33 +/- 0.16 cm; left branch: A = 0.95 +/- 0.25 cm/B = 1.30 +/- 0.24 cm). The mean blood flow velocity was also increased in the portal trunk (A = 15.96 +/- 6.17 cm/sec/B = 19.82 +/- 6.26 cm/sec) and in the left portal branch (A = 14.77 +/- 4.29 cm/sec/B = 19.92 +/- 6.88 cm/sec). CONCLUSION: The presence of a patent paraumbilical vein is related to significant biometric and hemodynamic variations in the portal venous system, in the setting of portal hypertension secondary to hepatosplenic schistosomiasis.     

Left ventricular systolic and diastolic asynchronism in patients with ischemic cardiopathy: its effects on ventricular filling]

To assess whether left ventricular asynchrony would influence filling in coronary artery disease, 27 patients with coronary artery disease and 39 normal subjects were studied by rest radionuclide angiography. Lower ejection fraction and peak filling rate were found in the coronary artery disease group (56% +/- 17% versus 65% +/- 6%, p less than 0.05; 1.8 +/- 0.7 versus 2.9 +/- 1.4 end-diastolic volumes/s, p less than 0.05). Moreover, the patients with coronary artery disease had a prolonged isovolumic relaxation period (114 +/- 86 ms versus 70 +/- 43 ms, p less than 0.05). Two indices of left ventricular asynchrony were evaluated: the coefficient of variation of regional time to end-systole, and the coefficient of variation of regional time to peak filling rate. The coefficient of variation of regional time to peak filling rate was higher in the coronary artery disease group (10.1% +/- 10%) than in the normal subjects (6.2% +/- 3.7%, p less than 0.05). Both these parameters were inversely related to global peak filling rate in the coronary artery disease group. These findings suggest that in patients with coronary artery disease left ventricular systolic and diastolic asynchrony plays a role in determining left ventricular diastolic properties.     

Echocardiographic evaluation of left ventricular diastolic function in patients with aortic valve stenosis

Impairment of left ventricular diastolic function in aortic valve stenosis occurs very early and precedes the impairment of systolic function. Aim was to examine left ventricular diastolic function and its association with severity of myocardial hypertrophy and clinical picture. The paper comprised 78 patients with isolated aortic valve stenosis in whom were performed ultrasonography and catheterization. No significant differences in parameters of diastolic filling were observed in patients with mild hypertrophy and preserved systolic function compared to healthy subjects. In patients with moderate myocardial hypertrophy, left ventricular filling was decreased in an early diastole (Emax 51 +/- 5 cm/s, Evti 6.4 +/- 1.1 cm) and increased in late diastole (Amax 88 +/- 11 cm/s, Avti 11.4 +/- 1.8 cm), while deceleration time was prolonged (DT 171 +/- 32 ms). Pulmonary vein flow was decreased during diastole (Dmax 33 +/- 5 cm/s, Dvti 7.6 +/- 2 cm). Pseudonormalization of flow through mitral valve was observed in patients with pronounced hypertrophy of left ventricular wall (mass > 180 g/m2): increase of the velocity during the phase of fast left ventricular filling (Emax 72 +/- 13 cm/s, Evti 9.8 +/- 2.1 cm), decrease during atrial contraction (Amax 31 +/- 6 cm/s, Avti 3.7 +/- 0.4 cm), reduction in deceleration time (DT 116 +/- 11 ms), while pulmonary vein flow velocity was increased during the early diastole (Dmax 64 +/- 17 cm/s, Dvti 10.7 +/- 2.2 cm). Likewise, significant correlation between clinical picture and type of blood flow through mitral valve was observed.     

Role of flowmetric analysis and of color-Doppler ultrasonography with contrast media in the different phases and follow-up of Graves' disease]

PURPOSE: The objectives of this study were: 1) to evaluate the role of color-Doppler ultrasonography (CDU) assessment of thyroid vascularity, measuring the peak systolic velocity (PSV) at the level of the inferior thyroid artery, and the intrathyroid vascularization in Graves' diseas; 2) to evaluate the role of contrast agent administration in predicting the relapse of hyperthyroidism or the biological activity of the disease after withdrawal of antithyroid drugs. PATIENTS AND METHOD: The study included 74 Graves' patients (59 F/ 15 M; mean age 45 years; range 23-71). Graves' disease was diagnosed according to the usual clinical and laboratory criteria. On the basis of the clinical and biochemical findings we divided Graves' patients into 4 different groups. Treatment was continued for at least 12 months, CDU examination was carried out after discontinuing therapy. Eight patients showed a relapse of hyperthyroidism within 5 months after suspension of therapy. In all cases the evaluation of intraparenchymal vascularization and PSV at the level of the inferior thyroid artery in basal conditions was followed by administration of contrast agent (Levovist, 300 mg/ml), with slow infusion (<2 ml/min) to avoid blooming artifact. Intraparenchymal vascularization was classified into 4 patterns according to Vitti et al. RESULTS: The value of the peak systolic velocity (PSV) at the level of the inferior thyroid artery was the best predictor of relapse. A value higher than 40 cm/sec was present in all the patients that showed relapse and only in two patients with stable remission. Administration of contrast agent is important to evaluate the biological activity of the disease. In the 5 patients exhibiting slightly increased vascularization after contrast agent administration we could assume the clinico-pathological recovery. CONCLUSIONS: CDU study of thyroid vascularization, based on the measurement of PSV at the level of the inferior thyroid artery and on the response to contrast agent administration is useful to distinguish three groups of patients: A) PSV >40 cm/sec with pattern III for at least 10 minutes from the beginning of the contrast agent administration (High risk of relapse); B) PSV <40 cm/sec with pattern II or III after contrast agent administration (Biological activity of the disease-Thyroiditis); C) PSV <40 cm/sec with Pattern I after contrast agent administration (Poor biological activity of the disease-recovery).     

拉萨地区高原肺水肿经颅多普勒21例分析

目的:通过经颅多普勒(TCD)检测,了解高原肺水肿(HAPE)患者颅内脑底动脉环上的主要动脉血流动力学及各血流的生理参数,为高原肺水肿的诊断及治疗提供一些参考.方法:将已确诊的HAPE患者,与颞窗通过低频脉冲多普勒(2MHZ),获得颅内脑底动脉环上的主要动脉的多普勒超声频移信号,进行TCD检测.结果:TCD检测后了解到颅内脑底动脉环上的主要动脉:颈内动脉末梢、大脑中动脉、大脑前动脉血流速度(收缩期血流速度,平均血流速度,舒张末期血流速度)与正常人的TCD测值相比明显增快,但舒张末期血流速度(VE )增快较收缩期血流速度(VP )不明显,故频谱仍为低阻波形,搏动指数(PI)、收缩期血流速度与舒张末期血流速度的比值(S/D)正常,阻力指数有所降低.结论:经TCD检测可知高原肺水肿患者在高原(在低氧环境下),颅内主要脑血管扩张,脑血流量增加即颈内动脉系统的MCA,ACA,PICA血流速度(Vs,Vm,Vd)增快,通过TCD检查可为高原医生早期诊断及治疗提供参考.     

In-plane coronary arterial motion velocity: measurement with electron-beam CT

PURPOSE: To determine the speed of and changes in the speed of coronary arterial movement during the cardiac cycle with electron-beam computed tomography (CT). MATERIALS AND METHODS: With electron-beam CT, 20 consecutive cross-sectional images were acquired at the mid right coronary artery (with 50-msec acquisition time, 8-msec intersection delay, 7-mm section thickness, and intravenous administration of 40 mL of contrast agent) in 25 patients. On the basis of the displacement of the left anterior descending, left circumflex, and right coronary arterial cross sections from image to image, movement velocity in the transverse imaging plane was calculated and was correlated with the simultaneously recorded electrocardiogram. RESULTS: The velocity of in-plane coronary arterial motion varied considerably during the cardiac cycle. Peaks were caused by ventricular systole and diastole and by atrial contraction. The mean velocity was 46.6 mm/sec +/- 12. 5 (SD). The mean velocity of right coronary arterial movement (69.5 mm/sec +/- 22.5) was significantly faster than that of the left anterior descending (22.4 mm/sec +/- 4.1) or the left circumflex coronary artery (48.4 mm/sec +/- 15.0). The lowest mean velocity (27. 9 mm/sec) was at 48% of the cardiac cycle. CONCLUSION: The lowest velocity of coronary arterial movement, which displays considerable temporal variation, was at 48% of the cardiac cycle.     

Hemodynamics revealed by Doppler sonography in patients who have undergone creation of transjugular intrahepatic portosystemic shunts: comparison of 10- and 12-mm metallic stents

OBJECTIVE: The purpose of this study was to determine whether differences exist in baseline flow velocities in the main portal vein and the stent after the creation of transjugular intrahepatic portosystemic shunts with 10- and 12-mm Wallstents. SUBJECTS AND METHODS: We used Doppler sonography to determine baseline flow velocities in the stent and the main portal vein in 80 patients (38 patients with 10-mm Wallstents dilated to 10 mm and 42 patients with 12-mm Wallstents dilated to 12 mm) who had undergone creation of trans jugular intrahepatic portosystemic shunts without complications. RESULTS: We found no significant difference in the maximum flow velocity in the stent between the patients with 10-mm stents (160.3+/-34.3 cm/sec) and those with 12-mm stents (164.4+/-33.8 cm/sec). We also found no significant difference in the minimum flow velocity in the stent between the 10-mm group (132.4+/-28.9 cm/sec) and the 12-mm group (126.7+/-28.3 cm/sec). However, flow velocity through the main portal vein was significantly higher in the patients with 12-mm stents (53.6+/-18.4 cm/sec) than in those with 10-mm stents (45.1+/-13.8 cm/sec) (p < .03). CONCLUSION: After creation of transjugular intrahepatic portosystemic shunts, baseline flow velocities in the main portal vein in patients with 12-mm stents exceeded those in patients with 10-mm stents, although neither maximum nor minimum flow velocities in the stent differed between these two groups of patients. These findings suggest that criteria for shunt malfunction that use flow velocity in the main portal vein may need modification when 12-mm stents are being evaluated.     

Detection of coronary artery disease by analysis of ventricular filling

Rapid left-ventricular (LV) diastolic filling assessed by radionuclide ventriculography is reevaluated in patients with coronary artery disease and normal LV systolic function considering the effects of age and heart rate. Thirty normal subjects were studied along with 44 patients with coronary artery disease and normal LV ejection fractions. The peak filling rate was not quite significantly different between the controls and patients (2.67 +/- 0.95 EDV/sec versus 2.25 +/- 0.65 EDV/sec, p = 0.08), and the time to peak filling rate was not different. When an inappropriate young control group was compared with coronary disease patients aged 40-65 yr, large differences in peak filling rate were seen. Sensitivity for detection of disease was very low (0%-9%) except when the inappropriate young control group was used. Thus, analysis of rapid diastolic filling cannot detect individual patients with coronary disease who have normal LV ejection fractions. Previous reports to the contrary may have suffered from failure to include the effects of age and heart rate.     

Griffiths' point: critical anastomosis at the splenic flexure. Significance in ischemia of the colon.

Griffiths' point is defined as the site of (a) communication of the ascending left colic artery with the marginal artery of Drummond, and (b) anastomotic bridging between the right and left terminal branches of the ascending left colic artery at the splenic flexure of the colon. It is upon this critical point at the splenic flexure that collateral circulation between the superior mesenteric artery and the marginal artery branch of the inferior mesenteric artery supplying the descending colon is dependent. Analysis of arteriographic studies shows that anastomosis at Griffiths' point is present in 48%, poor or tenuous in nine percent, and absent in 43%. This critical point is of significance in occlusive vascular impairment of the left colon, both in spontaneous instances and following surgical ligation of the inferior mesenteric artery, and in "nonocclusive" ischemic colitis. Its relationship to arteriosclerotic stenoses and low flow states is discussed. Individuals with absence of dependable anastomoses at Griffiths' point at the splenic flexure may be particularly vulnerable to low perfusion states and develop the syndrome of ischemic colitis. Complete arteriographic evaluation is necessary in ischemia of the colon. This includes particularly assessment of atherosclerotic changes at or near the ostia of the major visceral arteries and the vascular arrangement at Griffiths' point.     

Assessment of stenosis: implications of variability of Doppler measurements in normal-appearing carotid arteries.

PURPOSE: To examine the variability of Doppler measurements along the extra-cranial courses of the nondiseased common carotid artery (CCA) and internal carotid artery (ICA) and determine the effect of this variability on assessment of carotid arterial stenosis. MATERIALS AND METHODS: During the study period, 580 patients were referred for carotid arterial ultrasonography (US), including Doppler measurements of flow velocities in the proximal, middle, and distal portions of the CCA, in the bulb, and in the proximal and distal portions of the ICA. Eighty-five patients (average age, 59 years) with normal ICAs and CCAs formed the cohort for this study. RESULTS: The range of peak systolic velocity (PSV) measurement (maximum minus minimum) averaged 20 cm/sec +/- 13 in the CCA and 15 cm/sec +/- 13 in the ICA. ICA/CCA velocity ratios varied, depending on the CCA measurement location. In five arteries, PSV ratios exceeded a threshold of 1.8 (suggesting > or = 60% stenosis); in 23 arteries, end diastolic velocity ratios exceeded a threshold of 2.4 (also suggesting > or = 60% stenosis). Right-to-left CCA PSV ratios were abnormal in up to 26 patients (suggesting > 50% ICA stenosis), depending on where CCA measurements were obtained. When the CCA ratios were obtained at the same level, 16 were in the abnormal range. CONCLUSION: Variability of Doppler measurements in the CCA and ICA in patients without visible disease is substantial and could lead to inaccuracies in carotid arterial stenosis assessment.     

Detection of vascular complications in renal allografts with color Doppler flow imaging

One hundred ninety-five color Doppler flow (CDF) examinations were performed in 146 renal allografts to assess the capabilities of this technique in detecting intra- or extrarenal vascular complications. Conventional angiography was also performed in 44 transplants. In the group of transplants with angiographic correlation, CDF sonography enabled correct identification of 30 of 34 vascular complications. CDF showed 10 of 11 significant stenoses of the renal artery or of one of its main branches. There were two false-positive renal artery stenoses (one normal artery and one 40% stenosis). Nine of nine renal artery thromboses and the single pseudoaneurysm were also identified. Within the parenchyma, CDF sonography demonstrated five of five segmental infarcts, two of two postbiopsy arteriovenous fistulas, and three of six segmental or interlobar artery stenoses. Measurement of peak systolic velocity showed a significant difference (P less than .05) between a group (n = 8) with significant stenosis of the renal artery or one of its main branches (mean, 215.2 cm/sec +/- 32) and a group (n = 14) without stenosis (mean, 99.2 cm/sec +/- 19).