Reproducibility of noninvasive vascular laboratory measurements of the peripheral circulation

This study reports the reproducibility of noninvasive vascular laboratory measurements for the diagnosis of peripheral arterial occlusive disease and compares their variability to other clinical measurements, including pulse rate, hemoglobin, white blood cell count, blood urea nitrogen, and creatinine. To study the reproducibility of these measurements, we considered three components that affect the repeatability; the variation associated with the measurement process, the variation associated with transient changing characteristics of the patients with time, and the variation among the patients. It is useful to consider the variation of each component relative to the variation among the patients, measured in units of standard deviation. The variation associated with the measurement process (expressed as the relative precision) was determined by repeating the measurements in pairs at random times throughout the study period. The relative precision was 0.3% for the measurements of ankle-arm systolic blood pressure ratio and treadmill walking time, 2.7% for pulsatility index, and 1.2% to 4.2% for the other clinical, hematologic, and biochemical measurements. The temporal variations were determined by repeating the measurements over a 6-week period in 15 patients. The normalized long-term fluctuation was 1.7% for ankle-arm systolic pressure ratio, 3.2% for treadmill walking time, 7.5% for pulsatility index, and 1.3% to 5.5% for the other measurements. For each test, the 95% confidence interval for an individual patient's measurements and the values above which the difference between two successive measurements can be considered significantly different (95%) have been calculated. It is concluded that the reproducibility of standard vascular laboratory measurements compares favorably to the other clinical, hematologic, and biochemical measurements evaluated in this study.     

Doppler Velocimetry Parameters of Periurethral Vessels in Postmenopausal Incontinent Women Receiving Estrogen Replacement

Estrogen deficit causes significant alterations in the lower urinary tract of women, largely affecting urinary continence mechanisms. The urethral vascular bed accounts for about one-third of urethral pressure, and as it undergoes marked hormonal influence we became interested in investigating its behaviour both prior to and during estrogen replacement. We selected 25 postmenopausal patients with urinary stress incontinence and studied the periurethral vessels by means of Doppler velocimetry, analyzing the number of vessels, systolic peak, minimum diastole, resistance and pulsatility indexes and the A/B ratio, prior to estrogen replacement and after 1 and 3 months of hormone use. We concluded that estrogen replacement alone in postmenopausal women with urinary stress incontinence increased the number of periurethral vessels, systolic peak and minimum diastole; however, a trend of no statistical significance towards the reduction of resistance and pulsatility rates of periurethral vessels was found; nor was a significant difference in the A/B ratio shown.     

Power Doppler of the Urethra in Continent or Incontinent, Pre- and Postmenopausal Women

Urethral pressure should exceed bladder pressure, both at rest and on stress, for urinary continence to occur. A decrease in urethral pressure is a major factor explaining the pathogenesis of urinary incontinence. A number of elements, such as smooth and striated periurethral muscles, and connective, vascular and elastic tissues, contribute to urethral pressure. The periurethral vessels are influenced by hormonal changes during the menstrual cycle, during pregnancy and postmenopause. We studied the periurethral vessels in 97 women, 57 of whom were incontinent and 40 continent, using power color Doppler velocimetry. The number of periurethral vessels, systolic peak, minimum diastolic values, pulsatility and resistance indexes, as well as systolic–diastolic ratio, were assessed. Statistically significant differences were found between incontinent women in the premenopausal period and those in the postmenopausal period, regarding the number of periurethral vessels, systolic peak, minimum diastolic values, pulsatility and resistance indexes.     

Pulsatility Index of Temporal and Renal Arteries as an Early Finding of Arteriopathy in Diabetic Patients

The objective of this study was to investigate the relationship between alterations in the elasticity of the temporal and the renal arteries and the grade of arteriopathy, using the pulsatility index in type II diabetic patients and healthy volunteers. All individuals were divided into groups. Group A consisted of 15 patients without risk factors (hyperlipidemia, hypertension, obesity, and smoking) and had well-controlled diabetes mellitus as demonstrated by normal values of HbA1c. Group B had 20 patients with two risk factors (hyperlipidemia and hypertension) and normal HbA1c. Group C (25 patients) had four risk factors and high values of HbA1c, and group D consisted of 20 healthy individuals. All patients were examined by use of color Doppler ultrasonography. Pulsatility index values were measured in the temporal and renal arteries. Pulsatility indices of temporal arteries were higher in group C than in groups A and B, whereas for the renal arteries, no significant difference was detected between the four groups. In our study there seems to be strong correlation between increased values of pulsatility index, mainly in the temporal arteries, and grade of arteriopathy in type II diabetic patients.     

Undetected aorto-iliac insufficiency: a reason for early failure of saphenous vein bypass grafts for obstruction of the superficial femoral artery.

A series of 29 femoropopliteal bypass operations is described. The patients were selected carefully to exclude those with clinical and aortographic evidence of aorto-iliac disease. A pulsatility index was calculated from the velocity waveforms recorded over the common femoral and popliteal arteries. The pulsatility index is the ratio of the amplitude of the waveform to its mean height over one cardiac cycle. There was a highly significant difference in the result of the operation between patients with a pulsatility index of 4 or more in the common femoral artery and patients with a pulsatility index of less than 4. We concluded that calculation of this pulsatility index provides useful additional evidence when selecting patients suitable for a femoropopliteal bypass.     

Mediation Analysis of Aortic Stiffness and Renal Microvascular Function

Aortic stiffening, assessed by carotid-femoral pulse wave velocity, is associated with CKD. Transmission of excessive flow pulsatility into the low-impedance renal microvasculature may mediate this association. However, direct analyses of macrovascular–microvascular relations in the kidney are limited. Using arterial tonometry, iohexol clearance, and magnetic resonance imaging, we related arterial stiffness, GFR, urinary albumin excretion, and potential mediators, including renal artery pulsatility index, renal vascular resistance, and arterial volume in the cortex, in 367 older adults (ages 72–92 years) participating in the Age, Gene/Environment Susceptibility-Reykjavik Study. In a model adjusted for age, sex, heart rate, and body size, aortic stiffness was related to GFR (Slope of regression B=−2.28±0.85 ml/min per SD, P=0.008) but not urine albumin (P=0.09). After accounting for pulsatility index, the relation between aortic stiffness and GFR was no longer significant (P=0.10). Mediation analysis showed that 34% of the relation between aortic stiffness and GFR was mediated by pulsatility index (95% confidence interval of indirect effect, −1.35 to −0.29). An additional 20% or 36% of the relation was mediated by lower arterial volume in the cortex or higher renal vascular resistance, respectively, when offered as mediators downstream from higher pulsatility index (95% confidence interval of indirect effect including arterial volume in the cortex, −2.22 to −0.40; 95% confidence interval of indirect effect including renal vascular resistance, −2.51 to −0.76). These analyses provide the first evidence that aortic stiffness may contribute to lower GFR by transferring excessive flow pulsatility into the susceptible renal microvasculature, leading to dynamic constriction or vessel loss.     

Carotid doppler hemodynamics in posttraumatic intracranial hypertension

Repeated Doppler sonograms were performed on the common carotid arteries of patients with severe brain injury. The evolution of the flow-wave shape in 9 patients who developed massive intracranial hypertension and finally died with cerebral circulatory arrest demonstrated that, with increasing peripheral vascular resistance, the diastolic flow diminished while the peak systolic flow was not significantly affected. Thus, the so-called pulsatility index, a measure of the pulsatile characteristic of the sonogram, can be used as a semiquantitative measure of intracranial perfusion. Measurements on healthy control subjects provided pulsatility indexes between 1.5 and 2.0. In cases of posttraumatic brain edema, these values increased gradually. These data suggest that values higher than 3 are associated with severe intracranial hypertension and the decerebrate state. In angiographically demonstrated cerebral circulatory arrest, the pulsatility index was found to range between 6 and 8.     

Fourier Transform Infrared Imaging Microspectroscopy and Tissue-Level Mechanical Testing Reveal Intraspecies Variation in Mouse Bone Mineral and Matrix Composition

Fracture susceptibility is heritable and dependent upon bone morphology and quality. However, studies of bone quality are typically overshadowed by emphasis on bone geometry and bone mineral density. Given that differences in mineral and matrix composition exist in a variety of species, we hypothesized that genetic variation in bone quality and tissue-level mechanical properties would also exist within species. Sixteen-week-old female A/J, C57BL/6J (B6), and C3H/HeJ (C3H) inbred mouse femora were analyzed using Fourier transform infrared imaging and tissue-level mechanical testing for variation in mineral composition, mineral maturity, collagen cross-link ratio, and tissue-level mechanical properties. A/J femora had an increased mineral-to-matrix ratio compared to B6. The C3H mineral-to-matrix ratio was intermediate of A/J and B6. C3H femora had reduced acid phosphate and carbonate levels and an increased collagen cross-link ratio compared to A/J and B6. Modulus values paralleled mineral-to-matrix values, with A/J femora being the most stiff, B6 being the least stiff, and C3H having intermediate stiffness. In addition, work-to-failure varied among the strains, with the highly mineralized and brittle A/J femora performing the least amount of work-to-failure. Inbred mice are therefore able to differentially modulate the composition of their bone mineral and the maturity of their bone matrix in conjunction with tissue-level mechanical properties. These results suggest that specific combinations of bone quality and morphological traits are genetically regulated such that mechanically functional bones can be constructed in different ways.     

Renal vascular resistance in normal children – a color Doppler study

To investigate the relationship between age and renal vascular resistance and to establish nomative data of the systolic/diastolic ratio (S/D ratio), pulsatility index (PI), and resistant index (RI) of the renal artery in the normal pediatric population, we studied 252 normal children aged newborn to 13 years (a total of 449 kidneys) with a color Doppler unit. After the normality of the kidney was established, color flow mapping was performed to localize the segmental portion of the renal artery. Flow velocity waveforms were then obtained by pulsed Doppler, and S/D ratio, PI, and RI were calculated. Multiple regression analysis confirmed the age dependence of the S/D ratio, PI, and RI of the renal artery in normal children. Renal vascular resistance continuously declines after birth and stabilizes at the age of 102 – 130 months. Normative data for S/D ratio, PI, and RI of the renal artery in normal children were established for each age group. Since renal vascular resistance decreases with age and stabilizes at 8 – 10 years, we suggest using different normal ranges for each age group when studying renal vascular resistance in pediatric patients. Received October 5, 1995; received in revised form and accepted April 24, 1996     

Effect of crystalloid and colloid preloading on uteroplacental and maternal haemodynamic state during spinal anaesthesia for caesarean section

We have studied the effects of crystalloid 1 litre (lactated Ringer's) or colloid 0.5 litre (hydroxyethyl starch) preloading in 26 healthy parturients undergoing elective Caesarean section under spinal anaesthesia. Maternal placental uterine artery circulation was measured using a pulsed colour Doppler technique with simultaneous measurement of maternal haemodynamics. A high incidence of maternal hypotension was observed during spinal anaesthesia in the crystalloid group (62%) but the incidence was lower in the colloid group (38%). Central venous pressure was increased significantly in both groups after preload but decreased shortly after induction of spinal anaesthesia to baseline values. The mean pulsatility index (PI) in the uterine arteries did not change during preload or spinal block. A surprising finding was the widespread variation and some high values for the uterine artery PI after spinal anaesthesia. These individual increases in PI were transient and always returned to baseline values within 2 min. These results suggest that preloading with either solution is ineffective in preventing maternal hypotension and that changes in maternal heart rate, systolic arterial pressure and central venous pressure during spinal anaesthesia were not associated with rapid individual increases in uteroplacental vascular resistance. These changes seemed not to have any major effect, however, on the clinical condition of the newborn, as assessed by Apgar scores and umbilical artery pH values.      

S100B blood levels correlate with rewarming time and cerebral Doppler in pediatric open heart surgery

BACKGROUND: Brain hyperthermia, accompanying the rewarming phase of cardiopulmonary bypass (CPB), has been involved in the genesis of postoperative brain damage. Blood S100B levels are emerging as a marker of brain distress, and could offer a reliable monitoring tool at different times during and after open heart surgery. METHODS: Thirty-two patients undergoing repair of congenital heart disease with CPB and deep hypothermic circulatory arrest (DHCA) were monitored by S100B blood levels and middle cerebral artery Doppler velocimetry pulsatility index (MCA PI) before, during, and after surgical procedure at five predetermined time-points. RESULTS: Both S100B and MCA PI significantly increased, MCA PI values exhibiting a peak at the end of surgery time-point (p > 0.05), while S100B blood levels were increased at the end of CPB (p < 0.05). Multivariate analysis, with S100B levels measured at the end of CPB as dependent variable, showed a positive significant correlation with MCA PI (p = 0.04), with the CPB and the rewarming duration (p = 0.03 and p = 0.009, respectively). CONCLUSIONS: The present results show a significant correlation between a biochemical marker of brain damage and an index of increased cerebrovascular resistance, with higher levels during the rewarming CPB phase in pediatric open heart surgery.     

Effect of posture on popliteal artery hemodynamics

HYPOTHESIS: Marked peripheral vasodilation and rubor characterize critically ischemic limbs on dependency. We believe that intermittent claudication is also associated with peripheral hemodynamic changes on postural alteration, which differ distinctly from normal. Evaluation of such differences and understanding of the underlying physiological derangements may be essential in the development of treatments for intermittent claudication. We comparatively assess the effect of posture on lower limb arterial hemodynamics in normal subjects and in patients with intermittent claudication (or Fontaine II) due to peripheral vascular disease, determined in the popliteal artery. DESIGN: A cohort study. SETTING: A university-associated tertiary care hospital. PATIENTS: Thirty-seven legs of 29 normal subjects (group A) and 50 legs of 36 patients with intermittent claudication (ankle-brachial index range, 0.39-0.76; median, 0.57) (group B). INTERVENTIONS: Popliteal artery volume flow (vFl), mean velocity, and luminal diameter were measured on (1) recumbency, (2) sitting, and (3) return to recumbency in groups A and B using color duplex imaging. MAIN OUTCOME MEASURES: The pulsatility index, peak systolic velocity, and end diastolic velocity (EDV) were measured on (1) recumbency, (2) sitting, and (3) return to recumbency. RESULTS: Popliteal artery vFl in normal subjects decreased from 110 +/- 43 mL/min on recumbency to 57 +/- 27 mL/min on sitting (P<.001) and returned to 111 +/- 46 mL/ min on resumption of recumbency (P<.001). Similarly, in patients with intermittent claudication, vFl decreased from 113 +/- 52 mL/min on recumbency to 76 +/- 41 mL/min on sitting (P<.001) and increased on resumption of recumbency to 114 +/- 53 mL/min (P<.001). There was no difference (P = .97) in the vFl between the study groups on recumbency, but sitting vFl in normal subjects was significantly lower than in patients with intermittent claudication (P = .04). The mean velocity, peak systolic velocity, and EDV displayed a similar pattern of change as vFl. The pulsatility index in both groups increased significantly on sitting (P<.001) and decreased on return to recumbency (P<.001). All data are given as mean +/- SD. CONCLUSIONS: Lower limb arterial vFl, mean velocity, peak systolic velocity, and EDV decrease significantly (P<.001) when posture is altered from recumbency to sitting, in normal subjects and in patients with intermittent claudication. A decrease in the EDV and an increase in the pulsatility index on sitting indicate enhancement of arterial resistance to flow secondary to peripheral vasoconstriction. Quantitative differences between the groups in vFl (P<.04), EDV (P<.01), and pulsatility index (P<.001) on dependency indicate that the orthostatic vasoactive response in patients with intermittent claudication is significantly subdued, reflecting a marked derangement in venoarteriolar response.     

Doppler studies in normal kidneys of healthy children

Despite the widespread use of Doppler ultrasound in kidney diseases of adults and children, there are only a few, partially contradictory reports of normal values of resistance index (RI) and pulsatility index (PI) of renal perfusion in a healthy pediatric population. This study was carried out to determine normal values for these parameters in a larger group of probands. For the RI correlation with age was most pronounced in the right renal artery, with children over 6 years having a significantly lower RI than younger children. The PI was relatively independent of side and age. These results are somewhat different to previous reports. These differences may influence future Doppler sonographic investigations of acute and symmetrically affected kidneys (nephrological diseases). Our data suggest that the RI of the right renal artery might be most useful. In chronical or unilateral kidney diseases (unilateral ureteral obstruction, reflux, or operation) investigation of the PI in addition to the RI may aid diagnosis.     

Carotid Doppler Flow After Cardiopulmonary Bypass and Mild Hypothermia in Neonatal Piglets

Although the mechanisms of neurological disorders after cardiac surgery in neonates are still not fully understood, alterations in blood flow after cardiopulmonary bypass (CPB) may lead to cerebral injury. The aim of the study was the analysis of flow changes in the carotid artery of neonatal piglets after CPB. Ten neonatal piglets (younger than 7 days) were connected to the CPB and further management underwent three steps: (i) cooling to 32°C core temperature within 30 min; (ii) cardiac arrest under cardioplegic myocardial protection for 90 min; and (iii) rewarming to 37°C after cross‐clamp release (60 min of reperfusion). In summary, piglets were separated from CPB after a total duration time of 180 min. The blood flow was measured in the left carotid artery by an ultrasonic flow probe before CPB (baseline), immediately after CPB, 30 min, and 60 min after CPB. Additionally, the pulsatility index and the resistance index were calculated and compared. Finally, the relation of the carotid artery flow data with the corresponding pressure data at each time point was compared. After termination of CPB, the carotid artery mean flow was reduced from 28.34 ± 13.79 mL/min at baseline to 20.91 ± 10.61 mL/min and remained reduced 30 and 60 min after CPB termination (19.71 ± 11.11 and 17.64 ± 15.31 mL/min, respectively). Both the pulsatility and the resistance index were reduced immediately after CPB termination and increased thereafter. Nevertheless, values did not reach statistical significance. In conclusion, the carotid Doppler flow immediately after CPB and mild hypothermia in neonatal piglets was lower than before CPB due to reduced vascular resistance. Additionally, the pressure–flow relation revealed that immediately after CPB, a higher pressure is required to obtain adequate flow.     

Intraoperative assessment of coronary artery bypass graft: transit-time flowmetry versus angiography.

BACKGROUND: Transit-time flowmetry has been used to assess graft status intraoperatively. This study examines the validity of this method by comparing its results with the findings of simultaneously performed graft angiography. METHODS: The left internal thoracic artery (LITA) anastomosed to the left anterior descending artery (LAD) was assessed intraoperatively with both transit-time flowmetry and graft angiography in 30 patients. The patients were stratified into two groups based on intraoperative angiographic findings. In 18 patients (group A), the LITA and the LAD were well filled with contrast medium and the anastomosis was widely patent. In the other 12 patients (group B), spastic LITA or LAD was observed. Postoperative angiography was also performed before discharge from the hospital. RESULTS: The mean graft flow was 44.0 +/- 25.4 mL/min in group A and 23.4 +/- 10.0 mL/min in group B (p = 0.0129). Diastolic-dominant flow pattern was observed in both groups, and the ratio of peak diastolic flow to peak systolic flow and the percent diastolic time-flow integral were not statistically different between the groups. The pulsatility index was almost the same between the two groups and was acceptable in both. Postoperative angiography revealed that all grafts were patent without spasm or anastomotic stenosis. CONCLUSIONS: LITA graft status is satisfactory when high graft flow with diastolic dominance is obtained. When there is vasospasm but no anastomotic problems, decreased graft flow with an acceptable pulsatility index and diastolic augmentation is observed.     

Parathyroid hormone levels, calcium-channel blockers, and the dyslipidemia of nondiabetic hemodialysis patients

BACKGROUND: Experimental studies have shown that increased levels of parathyroid hormone (PTH) in uremia may cause elevation of intracellular calcium, predisposing to insulin resistance and lipid metabolism abnormalities. Administration of calcium-channel blockers (CCBs) in these models protects against the development of lipid profile abnormalities. This study evaluates the combined effect of intact PTH (iPTH) levels and administration of CCB on the lipid profiles of nondiabetic hemodialysis patients. METHODS: One hundred and eight non-diabetic hemodialysis patients were studied for 6 months. The population was divided into four groups, according to iPTH levels and administration of CCB: (A) iPTH<70 pg/mL, administration of CCB (n=16), (B) iPTH>300 pg/mL without administration of CCB (n=43), (C) iPTH<70 pg/mL without CCB administration (n=19), and (D) iPTH>300 pg/mL with CCB administration (n=30). Serum concentrations of total cholesterol, high-density lipoprotein (HDL), triglycerides, and albumin were measured on a monthly basis. RESULTS: All results are shown as mean SE. Total cholesterol values (in mg/ dL) were for group (A) 186 +/- 4, for group (B) 205 +/- 3, for group (C) 200 +/- 3, and for group (D) 203 +/- 4 [p NS between (C) and (D), p<.05 for all other comparisons]. Triglycerides values (in mg/dL) were for group (A) 171 +/- 9, for group (B) 199 +/- 6, for group (C) 190 +/- 6, and for group (D) 191 +/- 9 (p NS for all comparisons). HDL values (in mg/dL) were for group (A) 43.8 +/- 1, for group (B) 35.8 +/- 1, for group (C) 38.3 +/- 0.7, and for group (D) 37.2 +/- 0.7 mg/dL [p NS between (C) and (D), p<.001 for all other comparisons]. Low-density lipoprotein values (in mg/dL) were for group (A) 107.6 +/- 4.4, for group (B) 149.3 +/- 2.5, for group (C) 131.2 +/- 2.9, and for group (D) 126.8 +/- 4.1 [p NS between (C) and (D), p<.001 for all other comparisons]. Atherogenic index values, calculated as [triglycerides/HDL] ratio, were for group (A) 4.6 +/- 0.04 , for group (B) 6.2 +/- 0.04, for group (C) 4.9 +/- 0.03, and for group (D) 5.9 +/- 0.03 [p NS between (C) and (D), p<.004 for all other comparisons]. CONCLUSION: In nondiabetic hemodialysis patients, lipid profile abnormalities often accompany high levels of iPTH. The decrease in iPTH and/or the administration of CCB are accompanied by significant improvements in the main lipid profiles, including the atherogenic index.     

Hemodynamic controller for left ventricular assist device based on pulsatility ratio

Hemodynamic control of left ventricular assist devices (LVADs) is generally a complicated problem due to diverse operating environments and the variability of the patients: both the changes in the circulatory and metabolic parameters as well as disturbances that require adjustment to the operating point. This challenge is especially acute with control of turbodynamic blood pumps. This article presents a pulsatility ratio controller for LVAD that provides a proper perfusion according to the physiological demands of the patient, while avoiding adverse conditions. It utilizes the pulsatility ratio of the flow through the pump and pressure difference across the pump as a control index and adjusts the pump speed according to the reference pulsatility ratio under the different operating conditions. The simulation studies were performed to evaluate the controller in consideration of the sensitivity to afterload and preload, influence of the contractility, and effect of suction sensitivity. The controller successfully adjusts the pump speed according to the reference pulsatility ratio, and supports the natural heart under diverse pump operating conditions. The resulting safe pump operations demonstrate the solid performance of the controller in terms of sensitivity to afterload and preload, influence of the contractility, and effect of suction sensitivity.     

Diabetes mellitus worsens intrarenal hemodynamic abnormalities in nondialyzed patients with chronic renal failure

Duplex Doppler sonography has been reported to be useful in examining the intrarenal hemodynamic abnormalities in various renal diseases. We investigated the impact of diabetes on intrarenal hemodynamics in patients with chronic renal failure (CRF). The resistive index and pulsatility index of the renal interlobar arteries were measured using duplex Doppler sonography in 90 CRF patients (serum creatinine >130 and <800 mmol/l, mean age 59 +/- 11 years). Forty-eight patients had type 2 diabetes and 42 did not. Twenty-nine age-matched, healthy subjects served as controls. Both resistive index and pulsatility index were greater in CRF patients than in the controls (p < 0.0001). No significant differences existed in age, sex, body mass index, total serum cholesterol, serum creatinine, estimated creatinine clearance, or mean blood pressure between the diabetic CRF and nondiabetic CRF groups. Resistive index and pulsatility index were significantly increased in the diabetic CRF patients compared to the nondiabetic CRF patients (p < 0.0001). Multiple regression analysis of all CRF patients revealed that resistive index was independently affected by the presence of type 2 diabetes (F = 44.535), as well as decreased creatinine clearance (F = 18.157) and age (F = 15.160) (R(2) = 0.559, p < 0.0001). These results clearly demonstrated that intrarenal arterial resistance is significantly increased in CRF patients with type 2 diabetes compared to similar patients without diabetes. The impact of diabetes mellitus and advanced age on intrarenal hemodynamics may be due to intrarenal arteriosclerosis and interstitital lesions. Measurements of RI values in addition to conventional ultrasound imaging may add further information on such renal lesions.     

Carotid Artery Doppler Flow Pattern After Deep Hypothermic Circulatory Arrest in Neonatal Piglets

The mechanisms of cerebral injury after cardiac surgery in neonates are not clear. The aim of the study was the analysis of flow changes in the carotid artery of neonatal piglets after deep hypothermic circulatory arrest (DHCA). Eight neonatal piglets were connected to cardiopulmonary bypass (CPB) and underwent (i) cooling to 18°C core temperature within 30 min, (ii) DHCA for 90 min, and finally (iii) rewarming to 37°C after cross‐clamp release (60 min of reperfusion). The blood flow was measured in the left carotid artery by an ultrasonic flow probe before CPB (baseline; T₀), immediately after termination of reperfusion on CPB (T₁), 30 min later (T₂), and 60 min later (T₃). Additionally, the pulsatility index and the resistance index were calculated and compared. Finally, the relationship between the carotid artery flow and the corresponding pressure at each time‐point was compared. After termination of CPB (T₁), the mean carotid artery flow was reduced from 45.26 ± 2.58 mL/min at baseline to 23.29 ± 2.58 mL/min (P < 0.001) and remained reduced 30 and 60 min later (P < 0.001 vs. baseline). Both the pulsatility index and the resistance index were increased after termination of reperfusion, with the maximum occurring 30 min after CPB end. In conclusion, the carotid artery Doppler flow in neonatal piglets was reduced after DHCA, while the indices of pulsatility and resistance increased.     

Testicular-epididymal hemodynamics and inguinal hernia

Testicular-epididymal hemodynamics is studied by ultrasonographic color velocity imaging (CVI) in patients with primary, uncomplicated inguinal hernias. This procedure allows more precision than any other known Doppler system in measuring hemodynamic parameters such as peak systolic and diastolic velocity, resistance index and pulsatility index. The results of the exploration of 480 arteries of various testicular vascular territories are compared with those obtained by other authors in young healthy individuals using color Doppler. This procedure shows that the hernia does not cause significant alterations in the arterial circulation of the testicle and epididymis.