Ultrasound-guided lumbar plexus block in volunteers; a randomized controlled trial.

Background: The currently best-established ultrasound-guided lumbar plexus block (LPB) techniques use a paravertebral location of the probe, such as the lumbar ultrasound trident (LUT). However, paravertebral ultrasound scanning can provide inadequate sonographic visibility of the lumbar plexus in some patients. The ultrasound-guided shamrock LPB technique allows real-time sonographic viewing of the lumbar plexus, various anatomical landmarks, advancement of the needle, and spread of local anaesthetic injectate in most patients. We aimed to compare block procedure outcomes, effectiveness, and safety of the shamrock vs LUT. Methods: Twenty healthy men underwent ultrasound-guided shamrock and LUT LPBs (2% lidocaine­adrenaline 20 ml, with 1 ml diluted contrast added) in a blinded randomized crossover study. The primary outcome was block procedure time. Secondary outcomes were procedural discomfort, number of needle insertions, injectate spread assessed with magnetic resonance imaging, sensorimotor effects, and lidocaine pharmacokinetics. Results: The shamrock LPB procedure was faster than LUT (238 [sd 74] vs 334 [156] s; P=0.009), more comfortable {numeric rating scale 0­10: 3 [interquartile range (IQR) 2­4] vs 4 [3­6]; P=0.03}, and required fewer needle insertions (2 [IQR 1­3] vs 6 [2­12]; P=0.003). Perineural injectate spread seen with magnetic resonance imaging was similar between the groups and consistent with motor and sensory mapping. Zero/20 (0%) and 1/19 (5%) subjects had epidural spread after shamrock and LUT (P=1.00), respectively. The lidocaine pharmacokinetics were similar between the groups. Conclusions: Shamrock was faster, more comfortable, and equally effective compared with LUT. Clinical trial registration: NCT02255591

Displacement of popliteal sciatic nerve catheters after major foot and ankle surgery: a randomized controlled double-blinded magnetic resonance imaging study.

BACKGROUND: Popliteal sciatic nerve catheters (PSNCs) are associated with a high frequency of displacement. We aimed to estimate the frequency of catheter displacement after 48 h with magnetic resonance imaging (MRI) in patients with PSNCs after major foot and ankle surgery randomized to catheter insertion either with a short-axis in-plane (SAX-IP) approach perpendicular to the nerve or with a short-axis out-of-plane (SAX-OOP) approach parallel to the nerve. METHODS: Forty patients were randomly allocated to SAX-IP or SAX-OOP PSNC. Ropivacaine 0.75% 20 ml was injected via the catheter followed by ropivacaine 0.2% 10 ml h(-)1 infusion. Correct primary catheter placement was ensured after initial injection of local anaesthetic via the catheter. Forty-eight hours after insertion, MRI was performed after injection of saline with added contrast (Dotarem) via the catheter. The primary outcome was catheter displacement estimated as the frequency of spread of contrast exclusively outside the paraneurium. RESULTS: All patients had correct primary catheter placement. The frequency of displacement 48 h after insertion of the PSNC was 40% when inserted perpendicular to the nerve vs 10% parallel to the nerve (difference was 30 percentage points, 95% CI: 3-53 percentage points). The relative risk of displacement was four times larger (95% CI: 0.8-10, P<0.028) in the SAX-IP vs the SAX-OOP group. The morphine consumption was 150% greater in the SAX-IP compared with the SAX-OOP group. CONCLUSION: Popliteal sciatic nerve catheters for major foot and ankle surgery inserted with ultrasound guidance parallel to the sciatic nerve have a significantly lower frequency of displacement compared with those inserted perpendicular to the nerve. CLINICAL TRIAL REGISTRATION: NCT02200016.

The suprasacral parallel shift vs lumbar plexus blockade with ultrasound guidance in healthy volunteers--a randomised controlled trial.

Surgical anaesthesia with haemodynamic stability and opioid-free analgesia in fragile patients can theoretically be provided with lumbosacral plexus blockade. We compared a novel ultrasound-guided suprasacral technique for blockade of the lumbar plexus and the lumbosacral trunk with ultrasound-guided blockade of the lumbar plexus. The objective was to investigate whether the suprasacral technique is equally effective for anaesthesia of the terminal lumbar plexus nerves compared with a lumbar plexus block, and more effective for anaesthesia of the lumbosacral trunk. Twenty volunteers were included in a randomised crossover trial comparing the new suprasacral with a lumbar plexus block. The primary outcome was sensory dermatome anaesthesia of L2-S1. Secondary outcomes were peri-neural analgesic spread estimated with magnetic resonance imaging, sensory blockade of dermatomes L2-S3, motor blockade, volunteer discomfort, arterial blood pressure change, block performance time, lidocaine pharmacokinetics and complications. Only one volunteer in the suprasacral group had sensory blockade of all dermatomes L2-S1. Epidural spread was verified by magnetic resonance imaging in seven of the 34 trials (two suprasacral and five lumbar plexus blocks). Success rates of the sensory and motor blockade were 88-100% for the major lumbar plexus nerves with the suprasacral technique, and 59-88% with the lumbar plexus block (p > 0.05). Success rate of motor blockade was 50% for the lumbosacral trunk with the suprasacral technique and zero with the lumbar plexus block (p < 0.05). Both techniques are effective for blockade of the terminal nerves of the lumbar plexus. The suprasacral parallel shift technique is 50% effective for blockade of the lumbosacral trunk.

Assessment of dose to functional sub-structures in the lower urinary tract in locally advanced cervical cancer radiotherapy.

PURPOSE: To provide an analysis of dose distribution in sub-structures that could be responsible for urinary toxicity after Image-Guided Adaptive BrachyTherapy (IGABT) in Locally Advanced Cervical Cancer (LACC). METHODS: 105 LACC patients treated with radiochemotherapy and IGABT were selected. Sub-structures (bladder wall, trigone, bladder neck, urethra) were contoured on IGABT-planning MRIs. D2cm3 and D0.1cm3, ICRU Bladder-Point (ICRU BP) and Posterior-Inferior Border of Symphysis points (PIBS, PIBS + 2 cm, PIBS - 2 cm) doses were extracted. Internal-Urethral-Ostium (IUO) and PIBS-Urethra (PIBS-U) points were defined as urethral dose surrogates. Finally, the Vaginal Reference Length (VRL) was extracted. Values were converted into total EBRT + BT equivalent dose in 2 Gy fractions using α/ß = 3 and T1/2 = 1.5 h. RESULTS: Median D2cm3 for bladder and trigone were 71.7[interquartile-range:66.5;74.1]Gy and 57.8[53.3;63.6]Gy, respectively, while median D0.1cm3 were 82.2[77.6;89.1]Gy and 70.7[62.0;76.7]Gy, respectively. Median ICRU BP dose was 63.7[56.5;70.5]Gy and correlated with trigone D2cm3 and D0.1cm3, while bladder and trigone D2cm3 had poor correlation (R2 = 0.492), as well as D0.1cm3 (R2 = 0.356). Bladder neck D0.1cm3 was always lower than trigone D0.1cm3 and higher than IUO. Correlation between PIBS + 2 cm and IUO was poor (R2 = 0.273), while PIBS and PIBS-U were almost equal (R2 = 0.990). VRL correlated with dose to bladder base. CONCLUSIONS: The study confirmed that ICRU BP and trigone doses correlate. Bladder D2cm3 is not representative of trigone dose because hotspots are often placed in the bladder dome. VRL is a good indicator for bladder base sparing. In addition to D2cm3 and D0.1cm3 for whole bladder, ICRU BP, trigone D2cm3 and D0.1cm3, IUO and PIBS are useful for lower urinary tract reporting.

Effects of exercise and respiration on blood flow in total cavopulmonary connection: a real-time magnetic resonance flow study.

BACKGROUND: Little is known about blood flow and its relationship to respiration during exercise in patients with total cavopulmonary connection (TCPC). METHODS AND RESULTS: We studied 11 patients 12.4+/-4.6 years (mean+/-SD) of age 5.9+/-2.8 years (mean+/-SD) after TCPC operation. Real-time MRI was used to measure blood flow in the superior vena cava (SVC), inferior vena cava (IVC), and ascending aorta under inspiration and expiration during supine lower-limb exercise (rest, 0.5 and 1.0 W/kg) on an ergometer bicycle. IVC and aortic flow increased from 1.60+/-0.52 and 2.99+/-0.83 L/min per m2 at rest to 2.58+/-0.71 and 3.97+/-1.20 L/min per m2 at 0.5 W/kg and to 3.25+/-1.23 and 4.62+/-1.49 L/min per m2 at 1.0 W/kg (P< or =0.05). SVC flow remained unchanged. Resting flow in the IVC was greater during inspiration (2.99+/-1.25 L/min per m2) than during expiration (0.83+/-0.44 L/min per m2) (inspiratory/mean flow ratio, 1.9+/-0.5), and retrograde flow was present during expiration (11+/-12% of mean flow). The predominance of inspiratory flow in IVC diminished with exercise to an inspiratory/mean flow ratio of 1.5+/-0.2 (P< or =0.05) and 1.4+/-0.3 at 0.5 and 1.0 W/kg, respectively. CONCLUSIONS: In the TCPC, circulation IVC and aortic but not SVC flows increase with supine leg exercise. Inspiration facilitates IVC flow at rest but less so during exercise, when the peripheral pump seems to be more important.

Reduced cardiac reserve in amiodarone-treated pigs after cardiopulmonary bypass and cardioplegic arrest.

An animal model was designed for blinded study to elucidate whether cardiac pump failure after heart surgery in amiodarone-treated patients is due to interference between the drug and the surgical procedures. Seventeen adult pigs were treated with amiodarone for 30 days (study animals, 1,400 mg/day, n = 9; untreated control animals, n = 8) followed by exposure to cardiopulmonary bypass and topical cold cardioplegic arrest (Bretschneiders solution) for 60 min. Apart from 1 g of calcium, no inotropic agents were administered. Cardiac reserve was tested by ventricular pacing (200 beats/min for 30 min or until exhaustion). No difference in hemodynamic status was observed between the treated and the untreated group before pacing. Pacing duration in the amiodarone-treated pigs was 10 +/- 3 versus 22 +/- 4 min in control pigs (p less than 0.05). Only one amiodarone-treated pig survived 30 min of pacing compared with five control pigs (11% vs. 63%, p less than 0.05). The following variables differed significantly in the two groups during pacing: cardiac output, left ventricular pressure, arterial pressure and peak positive and negative first derivative of left ventricular pressure (dP/dt). Most marked were the changes in peak positive dP/dt, indicating a compromised systolic function. The two groups did not differ in preload or afterload at any time during the experiments.

Accurate noninvasive quantitation of blood flow, cross-sectional lumen vessel area and wall shear stress by three-dimensional paraboloid modeling of magnetic resonance imaging velocity data.

OBJECTIVES: We present a new method in which a priori knowledge of the blood velocity fields within the boundary layer at the vessel wall, combined with acquisition of high resolution magnetic resonance imaging (MRI) blood velocity data, allow exact modeling at the subpixel level. BACKGROUND: Methods are lacking for accurate, noninvasive estimation of blood flow, dynamic cross-sectional lumen vessel area and wall shear stress. METHODS: Using standard acquisition of MRI blood flow velocity data, we fitted all data points (n = 69) within the boundary layer of the velocity profile to a three-dimensional paraboloid, which enabled calculation of absolute volume blood flow, circumferential vessel wall position, lumen vessel area and wall shear stress. The method was tested in a 8.00 +/ 0.01-mm diameter glass tube model and applied in vivo to the common carotid artery of seven volunteers. RESULTS: In vitro the lumen area was assessed with a mean error of 0.6%. The 95% confidence interval included the specified tube dimensions. Common carotid mean blood flow was 7.42 ml/s, and mean (standard error) diastolic/systolic vessel area was 33.25 (0.72 [2.2%])/43.46 (0.65 [1.5%]) mm2. Mean/peak wall shear stress was 0.95 (0.04 [4.2%])/2.56 (0.08 [3.1%]) N/m2. CONCLUSIONS: We describe a new noninvasive method for highly accurate estimation of blood flow, cross-sectional lumen vessel area and wall shear stress. In vitro results and statistical analysis demonstrate the feasibility of the method, and the first in vivo results are comparable to published data.

Left ventricular blood flow patterns in normal subjects: a quantitative analysis by three-dimensional magnetic resonance velocity mapping.

OBJECTIVES: Magnetic resonance velocity mapping was used to investigate the hypothesis of a vortex motion within the left ventricle interacting with mitral valve motion and inflow velocity. BACKGROUND: In vitro flow visualization studies have suggested the presence of a large anterior vortex inside the left ventricle during mitral inflow. However, to our knowledge the occurrence of this phenomenon has not been demonstrated in the human left ventricle. METHODS: Magnetic resonance velocity mapping was performed in 26 healthy volunteers using a flow-adjusted gradient sequence for three-dimensional flow velocity acquisition in the long-axis plane of the left ventricle. By computer processing, the flow vectors in the left ventricle were visualized and animated dynamically. RESULTS: The early diastolic mitral inflow was apically directed, and a large counterclockwise anterior vortex was created within the left ventricle shortly after the onset of the mid-diastolic semiclosure of the anterior mitral leaflet. During mid-diastolic diastasis, mitral inflow ceased until the flow accelerated again at atrial systole. The final closure of the mitral valve was preceded by a smaller vortex seen at the tips of the mitral leaflets. At systolic ejection, all flow vectors were directed toward the left ventricular outflow tract. The anterior vortex had a radius of 1.62 +/- 0.24 cm (mean +/- SD), and the average angular velocity (i.e., the rotation of an element about the center of the vortex within the central core) was 30.08 +/- 9.98 radians/s. The maximal kinetic energy of the anterior vortex was 4.3 x 10(-4) +/- 7.1 x 10(-5) J. CONCLUSIONS: The hypothesis of a diastolic vortex formation in the human left ventricle was confirmed, and its close temporal relation to the motion of the anterior mitral leaflet was demonstrated.

Two-dimensional mitral flow velocity profiles in pig models using epicardial Doppler echocardiography.

OBJECTIVES: This study investigated the velocity distribution across the natural mitral valve. BACKGROUND: Information about the blood velocity distribution across the mitral valve is of interest in basic fluid dynamic studies of the natural mitral valve and is needed for precise cardiac output estimates by Doppler echocardiography. METHODS: The velocity distribution across the mitral valve was measured by epicardial Doppler echocardiography in ten 90-kg anesthetized pigs. By rotating the ultrasound transducer in 30 degrees intervals from the apical position, we constructed two-dimensional velocity profiles across the left ventricular inflow tract from diameters from each rotation arranged around a reference point. The time-averaged mitral velocity profile was calculated to estimate the error in cardiac output calculations that may occur with pulsed Doppler ultrasound when a single sample volume is used to record the mean velocity across the mitral orifice. RESULTS: The time-averaged diastolic cross-sectional mitral velocity profiles at the level of the mitral annulus and leaflet tips were variably skewed because of the development of a large anterior vortex in the left ventricle during the deceleration of early diastolic inflow and atrial systole. The ratio of the time-velocity integral of the center sample volume to the spatially averaged time-velocity integral was 1.13 +/- 0.15 (mean +/- SD) (range 0.80 to 1.32). Using regression analysis, we found a correlation between the degree of nonuniformity of the cross-sectional velocity distribution and the peak velocity of the anterior vortex (r = 0.65, p < 0.01). CONCLUSIONS: The assumption of a flat mean velocity profile across the mitral valve can introduce errors of +13 +/- 15% (mean +/- SD) in cardiac output measured with pulsed Doppler ultrasound when one is interrogating a single center sample volume.

Where to place the Doppler sample volume in the human main pulmonary artery: evaluated from magnetic resonance phase velocity maps.

OBJECTIVE: To give recommendations for the placement of Doppler sample volumes for blood flow assessment in the human main pulmonary artery. METHODS: In 10 healthy volunteers MR-phase velocity measurements were obtained and computing of the mean temporal blood velocity data was performed to guide single point Doppler velocity recordings. RESULTS: The mean temporal blood velocity profiles were consistently skewed with the lowest blood velocities towards the inferior/right vessel wall. Blood velocity indices (ratio of point to mean velocities, where a point equals a square of 4 pixels) varied considerably with the lowest indices located towards the inferior/right vessel wall. A centrally located fictive sample volume revealed an average blood velocity index value (average of all 10 subjects) of 1.08 (range 0.99-1.25; s.d. 0.08) where the central point was defined at maximum systole, and a value of 1.13 (range 0.97-1.34; s.d. 0.11) when the central point was defined in end-diastole. The mean of multiple sample volumes along the inferior/right to superior/left diameter revealed a blood velocity index of 1.01 (range 0.87-1.21; s.d. 0.09) in systole and 1.03 (range 0.87-1.19; s.d. 0.09) in diastole. CONCLUSIONS: For practical clinical purposes, single point estimation of the mean blood velocity in the pulmonary artery should be performed centrally. The use of multiple sample volumes placed along the inferior/right to superior/left diameter improves the mean velocity estimate in healthy volunteers. Further studies should be conducted to reinforce the basis for Doppler velocity recording in the diseased human pulmonary artery as well as to investigate other important determinants of Doppler-derived CO, namely angle of insonation and assessment of the cross-sectional area.

Transesophageal multiplane imaging of the human pulmonary artery: a comparison of MRI and multiplane transesophageal two-dimensional echocardiography.

OBJECTIVE: To evaluate the anatomical relationship between the esophagus and pulmonary artery including assessment of the correct transesophageal Doppler insonation angle into the mid-pulmonary artery trunk. METHODS: We evaluated the anatomical relationship between the esophagus and pulmonary artery (PA) from comparable magnetic resonance (MR) and transesophageal echocardiographic (TEE) multiple two-dimensional images (0 degree, 45 degrees, 90 degrees and 135 degrees clockwise rotation of the standard transverse scanning plane when seen bearfrom the esophagus) obtained in 10 healthy, young volunteers. RESULTS: The main PA could be visualized with both techniques in all 10 volunteers and provided highly identical images of good quality. A mean insonation angle of 35 degrees (range 26 degrees-46 degrees) for a fictive esophageal Doppler beam into the main PA was disclosed. The PA trunk was short with a mean length of 23.4 mm (range 17-30 mm). CONCLUSIONS: These anatomical data contradict the general assumption of alignment of the pulmonary artery and the transesophageal Doppler beam. Angle correction should be applied in the clinical setting using MTEE by rotation of the scanning plane to approximately 45 degrees. Ignoring the insonation angle of approximately 35 degrees may cause 20% underestimation of blood flow velocity and cardiac output in the PA.

The impact of ischemic heart disease on main pulmonary artery blood flow patterns: a comparison between magnetic resonance phase velocity mapping and transesophageal color Doppler.

OBJECTIVE: To give a detailed evaluation on main pulmonary artery blood velocity patterns, in patients with ischemic heart disease and to provide recommendations for pulsed Doppler sample volume placement, in order to optimize cardiac output estimation. METHODS: Using magnetic resonance phase and esophageal color Doppler velocity mapping in 12 patients with ischemic heart disease and undergoing coronary artery by-pass grafting, very similar data on pulmonary artery blood velocity patterns were provided for comparison with each other. RESULTS: Peak blood velocities were located in the inferior half of the main pulmonary artery cross-sectional area. Early after peak systole the highest velocities shifted towards the superior/left (major curvature) with a simultaneous decrease in velocities inferiorly. The velocity decrease further evolved into retrograde flow to the inferior/right (minor curvature). This feature was significantly enhanced compared to earlier findings in healthy volunteers. The mean temporal blood velocity profiles were asymmetrically skewed, thereby giving unreliable cardiac output estimates based on single point Doppler blood velocity recordings. The error incurred may amount to more than 100% in extreme cases. According to our data, optimal assessment of cardiac output should be based on multiple sample volumes placed along the inferior/right to superior/left diameter. CONCLUSIONS: MR-phase velocity mapping and multiplane transesophageal color Doppler recordings provided similar blood velocity patterns in patients with ischemic heart disease. The skewness of the mean temporal blood velocity profile is enhanced compared with healthy subjects, resulting in error in the assessment of CO by means of pulsed Doppler echocardiography. By using multiple Doppler sample volumes, the error can be minimized.

A model for acute haemodynamic studies in the ascending aorta in pigs.

Since data on velocity fields in the ascending aorta downstream of normal aortic valves in pigs have not yet been obtained velocity profiles were visualised using a hot film anemometer needle probe before and after total cardiopulmonary bypass and cold cardioplegic arrest. Furthermore, measurements were made during increased heart rate and cardiac output. A dynamic three dimensional visualisation of velocity fields showed a skewed clockwise rotating velocity profile, developing from peak systole and continuing throughout the systolic deceleration phase. This pattern was consistent regardless of the haemodynamic state. Heart rate was increased to 180 beats.min-1 and cardiac output by a maximum of 91%. It is concluded that the pig model is valuable for haemodynamic studies in the ascending aorta before and after cold cardioplegic arrest and that the velocity profiles found in this study are important basic data for velocity field studies downstream of artificial heart valves implanted in the aortic position.

Velocity fields and turbulent stresses downstream of biological and mechanical aortic valve prostheses implanted in pigs.

Since detailed knowledge about velocity fields downstream of heart valve prostheses obtained from in vitro studies has not been followed up by similar detailed studies in vivo a pig model for acute velocity field studies downstream of aortic valve prostheses was established. Two mechanical and two bioprosthetic valves were studied and a dynamic three dimensional visualisation of velocity fields one diameter downstream performed under different haemodynamic conditions in a total of 22 pigs. The Ionescu-Shiley pericardial valve had velocity fields very similar to the normal native porcine aortic valve. The Edwards-Carpentier porcine valve caused a jet type flow, and the valve design of the St Jude Medical and Björk-Shiley Monostrut valves was reflected in the velocity profile. Normalised (mean(SEM] systolic Reynolds normal stresses in the total cross sectional area were: native porcine 15(1.5) Nm-2; St Jude Medical 24(3.4) Nm-2; Björk-Shiley Monostrut 25(1.6) Nm-2; Edwards-Carpentier Supra-annular 51(6.6) Nm-2; Ionescu-Shiley Pericardial 19(2.0) Nm-2. Reynolds normal stresses were higher in areas of rapidly changing or constantly high velocity gradients.

Turbulent stresses downstream of three mechanical aortic valve prostheses in human beings.

High levels of turbulent stresses resulting from disturbed blood flow may cause damage to red blood cells and platelets. The purpose of this study was to evaluate the spatial distribution and temporal development of turbulent stresses downstream of three mechanical aortic valve prostheses in human subjects: the St. Jude Medical, the CarboMedics, and the Starr-Edwards silicone rubber ball. Blood velocity measurements were taken at 17 measuring points in the cross-sectional area of the ascending aorta 5 to 6 cm downstream of the aortic anulus with the use of a perivascular pulsed Doppler ultrasound system. Turbulence analysis was done for each of the 17 measuring points by calculating the radial Reynolds normal stresses within 50 msec overlapping time windows during systole. By coordinating the calculated Reynolds normal stress values for each time window and for all measuring points, computerized two-dimensional color-coded mapping of the turbulent stress distribution during systole was done. For the St. Jude Medical valves the highest Reynolds normal stress (27 to 63 N/m2) were found along the central slit near the vessel walls. The temporal development and spatial distribution of Reynolds normal stresses for the CarboMedics valves were quite similar to those of the St. Jude Medical valves with maximum Reynolds normal stress values ranging from 19 to 72 N/m2. The typical Reynolds normal stress distribution for the Starr-Edwards silicone rubber ball valves was asymmetric, revealing the highest Reynolds normal stresses (11 to 56 N/m2) at various locations in the annular region between the ball and the vessel wall. The spatial distribution and temporal development of turbulent stresses downstream of the three investigated mechanical aortic valve prostheses correlated well with the superstructure of the valves. The maximum Reynolds normal stresses for the three valve types were in the same order of magnitude with exposure times sufficient to cause sublethal damage to red blood cells and platelets.

A histomorphometric method for evaluating topographic differences in degree of early atherosclerosis within the human aorta.

The aim of the study was to develop an unbiased topographically oriented method of evaluating early atherosclerotic lesions in the aorta and to apply this to a series of human aortas from young adults. A systematic sampling procedure and histomorphometric analysis of intimal thickening is described. Results from a group of 15 young adults (aged 18-40 years) showed a characteristic pattern with increasing intimal thickening when moving distally from the thoracic to the upper and finally to the lower abdominal aorta, but also a shift in the localization of the most pronounced intimal thickening from the posterior to the anterior and back to the posterior aspect. This pattern was found in aortas both with minimal and with more pronounced atherosclerosis, and supports the view that the early intimal thickening precedes the atherosclerotic lesions and marks the sites of predilection for the more advanced disease processes. An increase in intimal thickness with age could be demonstrated in the aortas without overt atherosclerosis. The simple sampling procedure, well-defined sampling sites, and ability to demonstrate and quantitate differences in intimal thickening and plaque morphology make this method well suited for relating morphometric data to other parameters of interest when studying the etiology and dynamics of atherosclerotic disease.

Multiplane transesophageal Doppler echocardiographic measurements of the velocity profile in the human pulmonary artery.

Eight healthy, unsedated volunteers were studied to introduce a new non-invasive method for detailed blood velocity measurements and to evaluate flow patterns in the human pulmonary artery during end-expiratory apnea. With a multiplane transesophageal ultrasonic probe, spectral Doppler velocity registration was performed in nine different spatial locations across the vessel area. The pulmonary trunk could be visualized in all patients. The mean temporal velocity profile was virtually flat despite an instantaneous skewness that rotated counterclockwise up to 180 degrees. Furthermore, our data indicate that a good estimate of the temporal and spatial mean velocity can be obtained from velocity recordings based on centrally placed sample volumes. This makes the future application of Doppler-based measurement of cardiac output in the pulmonary artery hopeful. The ability of multiplane transesophageal echocardiography to estimate the area of the elastic human pulmonary artery, however, has to be evaluated more extensively before the clinical importance of this tool for measurement of cardiac output can be established.

Aminopropeptide of human procollagen type I: a marker for the identification of blood from children in the mosquito blood meal.

A capture enzyme-linked immunosorbent assay (ELISA) to distinguish between blood from children and adults in the mosquito blood meal was examined using the alpha 1 chain of the aminopropeptide of human procollagen type I (PINP) as antigenic marker. Rabbit anti-human PINP (alpha 1) antibody was used as catching antibody, and either normal serum from 288 African and 58 Caucasian children and adults, or blood meals from 93 fed Aedes aegypti, were examined. PINP in excess of 40 optical density units (ODU) was detected in all children aged 0-13 years, whereas adults aged 21-77 years had PINP levels less than 25 ODU. In the transitional age group (14-20 years), the PINP levels ranged from 1 to 166 ODU. The PINP levels in 95% of the mosquito blood meals obtained from children exceeded the control levels, using 13 ODU as a cut-off value, whereas none of the blood meals from adults exceeded 13 ODU. The PINP levels in the mosquito blood meals were constant 1 and 8 h after ingestion, but they had decreased significantly after 16-19 h. Our data suggest that the test can be used to identify host preferences in studies of mosquitoes collected within 16 h after the blood meal. A field evaluation is necessary to determine the potential of the antigenic marker PINP as a tool in the identification of mosquito host preference.

Lymphatic filariasis in Uganda: baseline investigations in Lira, Soroti and Katakwi districts.

Baseline epidemiological investigations on lymphatic filariasis were conducted for the first time in Uganda in 3 communities in the districts of Lira (Alebtong area), Soroti (Lwala area) and Katakwi (Obalanga area), located to the north of Lake Kyoga at an altitude of 1000-1100 m above sea level. Individuals from the communities were examined, in April-August 1998, for Wuchereria bancrofti specific circulating antigen (by ICT card test), microfilaraemia (by counting chamber and stained blood-smear techniques) and chronic clinical manifestations of lymphatic filariasis. Endophilic mosquitoes were sampled and dissected for filarial larvae. Prevalences of circulating filarial antigen positivity were 29%, 18% and 30% in the Alebtong, Lwala and Obalanga communities, respectively. Microfilaria (mf) prevalences were 18%, 9% and 21%, and geometric mean mf intensities among mf-positive individuals were 306, 171 and 402 mf/mL blood, in the same communities. Examination of stained blood smears revealed mf of both W. bancrofti and Mansonella perstans, but more than 80% of mf-positive individuals harboured the first of these parasites. Prevalences of hydrocoele in adult (> or = 20 years) males were 28%, 7% and 17%, and prevalences of limb elephantiasis in adults were 9%, 4% and 4%, in the Alebtong, Lwala and Obalanga communities, respectively. Anopheles gambiae s.l. (mainly An. gambiae s.s.) and An. funestus were common in all 3 communities, and showed W. bancrofti infectivity rates of 1.1-1.7% and 1.3-2.9%, respectively. It is concluded that lymphatic filariasis is highly endemic in these high-altitude areas of Uganda, with An. gambiae s.l. and An. funestus being the main vectors.

Lymphatic filariasis on the coast of Ghana.

Parasitological, clinical and entomological surveys for lymphatic filariasis were carried out in 6 villages and 3 towns on the coast of Ghana. Few or no filarial infections were observed in the towns or in the villages east of Accra. However, Wuchereria bancrofti microfilaraemia was common in the 4 western villages, with overall prevalences of 9.2%-25.4% and overall microfilariae (mf) geometric mean intensities of 321-1172 mf/mL of blood. In the same villages, hydrocele affected 8.5%-27.9% of adult males (aged > or = 20 years), and 5.6%-6.6% of adult individuals had elephantiasis (mainly of the legs). In general, the patterns of filarial infection and disease in the endemic villages resembled those observed in endemic villages in the coastal part of East Africa, with the exception that in the Ghanaian focus more females than males were affected by elephantiasis. Entomological surveys revealed that Anopheles gambiae s.l. and A. funestus were vectors of filariasis in the endemic villages. Only negligible prevalences of microfilaraemia were observed in town communities located close to highly endemic villages. Control of filariasis in this area is difficult with presently available measures, and new control tools, especially development of new drug regimens for mass treatment, are greatly needed.