[Principles of hemodynamics and sonographic techniques for the evaluation of veins of the neck and limbs]. / Notions d'hémodynamique et techniques ultrasonores pour l'exploration des veines du cou et des membres.

Deep venous thrombosis and venous insufficiency are now easily diagnosed with US imaging. US allows anatomic evaluation of the vessel walls and dynamic evaluation of flow velocities. Knowledge of vascular anatomy and physiology is required to interpret US data. The sensitivity of US for the diagnosis of deep venous thrombosis is up to 95% at the leg level, 98% at the popliteal level, and 100% at the femoral level with a specificity of nearly 100%. Venography is thus rarely performed. The sensitivity for the diagnosis of deep venous thrombosis at the neck level is up to 90%. Follow-up can easily be performed because of the wide availability of US.

Whole-body (201)Tl scintigraphy can detect exercise lower limb perfusion abnormalities in asymptomatic diabetic patients with normal Doppler pressure indices.

Significant lower limb arterial obstruction is usually detected by Doppler ankle-brachial pressure index (ABPI) measurement. However, ABPI is non-contributory in cases of diabetic medial sclerosis or calcifications and is unsuitable for the detection of small vessel involvement. Thallium-201, a perfusion agent, is frequently used for the investigation of coronary artery disease, and whole-body (201)Tl scintigraphy (WBS) has also been reported to be useful in the assessment of peripheral artery disease (PAD). Thus, we evaluated the clinical feasibility of simultaneous myocardial and lower limb perfusion assessment. WBS was performed after treadmill exercise and myocardial scintigraphy, and again 4 h later. Calf (201)Tl fractional activities (percentage of whole-body (201)Tl uptake) were calculated. We determined a threshold value of normal post-exercise calf (201)Tl uptake (mean of the (201)Tl fractional uptakes minus 2 SD) in a control group of nine healthy volunteers. We checked its accuracy in a pilot group of 25 diabetic patients with proven PAD. This method permitted the detection of lower limb perfusion abnormalities in 38% of 47 asymptomatic diabetic patients with no evidence of PAD. In conclusion, for asymptomatic diabetic patients, whole-body (201)Tl scintigraphy after a treadmill test seems an efficient method of showing lower limb perfusion abnormalities not detected by ABPI measurement. It allows the evaluation of vascular status with no additional inconvenience for patients when performed after myocardial scintigraphy.

Parasympathetic activity during parabolic flight, effect of LBNP during microgravity.

BACKGROUND/HYPOTHESIS: During parabolic flight, in the standing position, changes are partly due to an acute shift in fluid between the lower extremities, the head and the thorax (Vaïda P, et al. J Appl Physiol 1997; 82:1091-7; and Bailliart O, et al. J Appl Physiol 1998; 85:2100-5). We hypothesized that modifications of parasympathetic activity associated with changes in hydrostatic pressure gradients induced by changes in gravity could be detected by analysis of short time periods. METHODS: We assessed heart rate variability (HRV) in 11 healthy volunteers by indices of temporal analysis (NN, SDNN, RMSSD) and normalized indices such as coefficients of variation CV-SDNN and CV-RMSSD and ratio SDNN/RMSSD. A lower body negative pressure (LBNP) at -50 mm Hg was randomly applied during the microgravity phase (0 Gz) to counteract the lack of hydrostatic pressure in the lower part of the body. RESULTS: NN, CV-SDNN and CV-RMSSD decreased during hypergravity phases and increased during microgravity and during early normogravity (1 Gz) period at the end of parabolas. With LBNP changes are less pronounced at 0 Gz and in the 1 Gz post parabolic period. CONCLUSION: We concluded that parasympathetic nervous activity is recordable by temporal analysis of HRV during short periods of time. LBNP applied during 0 Gz phase reduced the parasympathetic activation at 0 Gz and post parabolic 1 Gz.

Evidence of fetal cerebral vasodilatation induced by submaximal maternal dynamic exercise in human pregnancy.

To investigate the relationship between maternal exercise and fetal circulatory responses in humans during the third trimester of pregnancy, changes in uterine, umbilical and fetal cerebral circulations were measured by pulsed-Doppler ultrasound method in 14 healthy volunteer pregnant women before and just after a moderate non-exhaustive exercise. Maternal heart rate increased significantly reaching 80% of the theoretical maximal heart rate (TMHR) while uterine resistance indices did not change. The fetal heart rate and umbilical mean velocity were unchanged while umbilical resistance index decreased slightly (0.58 +/- 0.06 versus 0.62 +/- 0.07, P < 0.05). The fetal internal carotid artery mean velocity increased (23.2 +/- 5.3 versus 20.4 +/- 4.1 cm/s, P < 0.02) and the cerebral resistance index decreased (0.71 +/- 0.11 versus 0.80 +/- 0.10, P < 0.01). We conclude that submaximal maternal exercise at 80% of TMHR does not significantly alter uterine perfusion but involves a slight fetal cerebral vasodilation which could be due to a moderate fetal hemoglobin desaturation.

[Maximal exercise in spinal cord injured subjects: effects of an antigravity suit]. / Exercice physique maximal chez le blesse medullaire: interet de la contention veineuse sous-lesionnelle.

Paraplegics have low aerobic capacity because of the spinal cord injury. Their functional muscle mass is reduced and usually untrained. They have to use upperbody muscles for displacements and daily activities. Sympathic nervous system injury is responsible of vasomotricity disturbances in leg vessels and possible abdominal vessels, proportionally to level injury. If cord injury level is higher than T5, then sympathic cardiac efferences may be damaged. Underbody muscles atrophy and vasomotricity disturbances contribute to phlebostasis. This stasis may decrease venous return, preload and stroke volume (Starling). To maintain appropriate cardiac output, tachycardia is necessary, especially during exercise. Low stroke volume, all the more since it is associated with cardio-acceleration disturbances, may reduce cardiac output reserve, and so constitutes a limiting factor for adaptation to exercise. The aim of this study was to verify if use of an underlesional pressure suit may increase cardiac output reserve because of lower venous stasis, and increase performance. We studied 10 able-bodied and 14 traumatic paraplegic subjects. Able-bodied subjects were 37 +/- 6 years old, wellbeing, not especially trained with upperbody muscles: there were 2 women and 8 men. Paraplegics were 27 +/- 7 years old, wellbeing except paraplegia, five of them practiced sport regularly (athletism or basket for disabled), and the others just daily propelled their wheelchair; there were 5 women and 9 men. For 8 of them, cord injury levels were located below T7, between T1 and T6 for the others. The age disability varied from 6 months to 2 years for 9 of them, it was approximately five years for 4 of them, and 20 years for one. We used a maximal triangular arm crank exercise with an electro-magnetic ergocycle Gauthier frame. After five minutes warm up, it was proceeded in one minute successive stages until maximal oxygen consumption is raised. VO2, VCO2, RER were measured by direct method with an Ergostar analyser every 30 seconds. Heart rate was registered continuously using a cardio-frequence-meter Baumann, and ECG was observed on a Cardiovit electro-cardiograph. Each subject reached maximal exercises on different days: one without any contention, and the other one with abdomen and legs contention using an antigravity suit, inflated to 45-50 mm Hg for legs and 30-40 mm Hg for abdomen. The able-bodied subjects VO2 peak was 24 +/- 5.8 mL min-1 kg-1, without any change on peak VO2 and on cardiac frequency when pressure suit was used. Results were different for paraplegics: peak VO2 was significantly higher (21.5 +/- 6.5 mL min-1 kg-1 without contention and 23.8 +/- 6.3 mL min-1 kg-1 with contention), heart rate was significantly lower at all stages of exercise with antigravity suit and comfort was better during exercise and rest. In our study, contention contributed to increase paraplegics's performances, but responses depend also on spinal cord level, injury age, spasticity. Therefore, testing paraplegics using an antigravity suit may be useful to determine if neurovegetative disturbances significantly modify their cardiac adaptation and capability. If gravity suit is efficient, contention tights might be prescribed, with respect to subject's legs measurements. But, because these tights are very difficult to put on, their efficiency has to be proved before, the motivation of the subject is essential too.

Simultaneous ultrasonic measurement of carotid blood flow and intracerebral haemodynamics in man.

Common carotid blood flow and middle cerebral artery velocities were determined simultaneously by using a range gated Doppler velocimeter and transcranial apparatus in ten subjects. Middle cerebral artery velocities were used as an index of cerebral resistance. Different gas mixture concentrations were breathed in order to change cerebral haemodynamic conditions. In each condition there was a simultaneous modification of blood gases and cervicocerebral haemodynamics in common carotid blood flow and cerebral vascular resistance index. Carotid blood flow and the resistance index in middle cerebral artery changed also on opposite side. Acute hypercapnia in normoxia increases common carotid blood flow by 33% and simultaneously decreases cerebral resistance index by 11%. Normocapnic hyperoxia was associated with a fall in common carotid blood flow by 13% and with an increase in cerebral resistance index by 7%. There was a inter-subject statistically significant relation between common carotid blood flow and index of cerebral resistances (0.78 < r < 0.98). However there was an individual reactivity with large scatter when data from different subjects were pooled. Nevertheless the results provide evidence that changes in middle cerebral artery resistance indices are reflected by common carotid blood flow modifications.

Improvement of digital coronary angiography: high resolution processing coupled with a real time functional synchronization procedure.

The use of Digital Subtraction Angiography in coronary applications is restricted by the difficulty in: 1. Obtaining a good resolution of the distal branches. 2. Avoiding, for the purpose of subtraction, the motion artifacts induced by artery and background displacement during the cardiac and respiratory cycles. 3. Preserving the dynamic vascular motion. 4. And storing the digital dynamic information on a permanent support. We used for this study an angiography system, based upon a high resolution 45 MIPS-32 Mbyte image processor, interfaced with a 2.75 Gbyte Winchester drive allowing the real time storage of either 30 frames/s in the 512*512*8 bits matrix or of 7.5 f/s in the 1024*1024*8 bits matrix. To preserve the most important dynamic informations on the basis of the 7.5 f/s maximal storage rate, we developed a synchronization device able to recognize in real time, from chronologic delays derived by using both ECG and Aortic Pressure curves, the functional End-Diastolic (ED) and the End-Systolic (ES) positions, even in the case of heart rates varying during the procedure. The ED and the ES images are stored together with the Mid-Systolic (MS), the 1/3-Diastolic (1/3D) and 2/3-Diastolic (2/3D) images. To establish the validity of this sampling method, which uses a reduced number of frames per cardiac cycle, 7200 coronary injections performed during 450 routine coronary angiographies were compared by two independent observers (A and B), using: first a Digital (D) 5 frames/cycle sequence, and secondly a cine Film (F) 50 frames/s sequence acquired immediately after the corresponding D injection. The D technique resulted in the best image and diagnostic quality, particularly when the F quality was estimated 'fair' or 'poor' by both observers, and in an important reduction on X-Ray doses. The visualisation of the sequential ED, MS, ES, 1/3D and 2/3D frames gives the possibility: 1. of saving the dynamic information, as a regular sample of functional images can be displayed with a cine loop technique. 2. of facilitating cardiac synchronized subtractions. 3. of reducing the amount of frames per cycle, thus allowing an important reduction of X-ray doses and the digital and permanent storage of the most important cardiac cycles.

[Comparison of humeral blood flow during rewarming and recooling of the hand in normal subjects or presenting Raynaud's phenomenon]. / Comparaison des débits sanguins huméraux lors du réchauffement et du refroidissement de la main chez des sujets sains ou présentant un phénomène de Raynaud.

Vascular reactivity to heat and cold was studied in 11 normal subjects without vascular disease and in 23 patients with Raynaud's phenomenon (etiologies: Raynaud's disease, scleroderma, thoracic outlet syndrome). The study of hand and digital temperatures and brachial artery blood flow was performed in ambiant conditions (room temperature 23.5 +/- 1 degree C) and after thermal (cold or warm exposure: 10, 33 and 40 degrees C), mechanical and metabolic modifications (with a wrist tourniquet). In these conditions, blood flow was studied at each temperature, before, during and after 3 minutes ischemia of the hand. Analysis of results showed that vasomotricity possibilities were preserved but that responses were not identical. Patients with primary Raynaud's phenomenon, and even more those with scleroderma as well, had reduced brachial artery blood flow after cooling (10 degrees C). After ischemia, maximal blood flow was also reduced. The microcirculatory disease existing in Raynaud's phenomenon limits the vasodilator capacity of hand vessels, but probably more in tissues with vascular lesions. Vasodilation seems to be limited during exposure to low well as high temperatures, but vasoconstriction capacity is not disturbed.

Effects of bisoprolol on local vascular resistance.

Changes in systolic and diastolic blood pressure, heart rate, arterial blood flow and vascular resistance in the arm and in the leg were investigated in 9 healthy volunteers (22-40 years) after oral dosing with bisoprolol 10 mg, propranolol 40 mg, and placebo in a randomized double-blind cross-over study. Arterial blood flow and vascular resistance were determined in brachial and femoral arteries with unimpeded circulation, after exclusion of the hand or foot by placing a tourniquet on the wrist or ankle, and during post-ischaemic hyperaemia. Distal arterial occlusion allows one to isolate a predominantly muscular circulation in the forearm or, to a lesser extent, in the leg. Both active drugs induced a significant fall in heart rate and systolic blood pressure versus placebo with no significant difference between the drugs. Brachial and femoral flow rates were reduced by both drugs probably due to a fall in cardiac output, but the two beta blockers produced different effects on vascular resistance: propranolol significantly increased brachial vascular resistance compared with placebo and bisoprolol, both during unimpeded circulation and during occlusion of the hand by a wrist tourniquet. Bisoprolol had no influence on brachial vascular resistance. Both drugs induced small increases in femoral vascular resistance. The different action on local vascular resistance in the brachial artery territory could be interpreted as the expression of the high beta 1 selectivity of bisoprolol leaving the vascular beta 2 receptors unopposed, whereas non-selective propranolol acts on both beta-adrenoceptor subtypes.

Experiences with a new procedure for the measurement of the ophthalmic artery pressure: ophthalmomanometry-Doppler.

A novel, noninvasive method to determine simultaneously ophthalmic artery pressure (OAP) and flow direction, called ophthalmomanometry-Doppler, is presented. This technique uses a device consisting of a chamber with an apperture hermetically adaptable to the orbital borders. The chamber is equipped with a Doppler probe and an arrival pipe for compressed air connected to a manometer. The OAP measurement procedure consists of applying a pressure in the chamber while the Doppler probe detects periorbital Doppler signals. The systolic OAP corresponds to the Doppler signal disappearance during chamber pressure increase. Studies performed on normal subjects with direct recording of the internal carotid artery pressure (ICP) and indirect determination of the brachial artery pressure (BAP) demonstrated that OAP values assessed by the ophthalmomanometry-Doppler device were highly correlated with simultaneous ipsilateral intra-arterial systolic ICP measurements (r = 0.95, n = 10) and with simultaneous recordings of the BAP (r = 0.85, n = 40). The ophthalmic pressure index (OAP/ICP and OAP/BAP ratio, respectively) ranged from 0.60-0.77 with a mean (+/- SD) of 0.68 (+/- 0.04) in the 50 normal subjects. Preliminary clinical trials show diminished OAP/BAP ratios in patients with occlusive carotid disease ipsilateral to hemodynamically significant lesions. The values obtained on these normal subjects provide baseline data for further investigation of pathologic conditions. This new procedure is simple, convenient, rapid, and safe and provides reproducible information on both OAP and flow parameters, which are important indices in the evaluation of severe carotid artery disease.

[Noninvasive determination of stroke volume with impulse Doppler echocardiography: comparison with the Fick method]. / Nichtinvasive Herzzeitvolumenbestimmung mit Impulsdoppler-Echokardiographie: Vergleich mit der Fick-Methode.

Pulsed Doppler echocardiographic studies were performed in 14 patients (eleven with mitral valve disease, two with coronary artery disease, one with aortic and mitral valve replacement) for determination of cardiac output and the results compared with those obtained from simultaneous measurements carried out according to the Fick principle. Determination of cardiac output and stroke volume was achieved with a pulsed Doppler instrument specifically designed in our laboratory (repetition frequency 10 kHz, maximal penetrance 7.7 cm, ultrasonic beam diameter 3 cm at a distance of 5 cm from the transducer). Doppler measurements of the instantaneous blood flow velocity in the ascending aorta were obtained with the transducer in a suprasternal position. Through integration of the mean spatial velocity over an entire cardiac cycle, the distance traversed by the blood during one heart beat was obtained and then multiplied by the echocardiographically-determined cross-section area of the aorta and the heart rate to yield the cardiac output. There was a statistically-significant linear correlation between the cardiac output determined by Doppler (CO-D) and Fick (CO-F): CO-D = 0.92 CO-F X 0.48, r = 0.85, n = 14. The mean values for the two methods were 3.89 and 3.68 1/min, respectively. The correlation between the two methods improved if only those patients with sinus rhythm were taken into consideration (CO-D = 1.05 CO-F - 0.21, r = 0.93, n = 11). The results show that the pulsed Doppler method used enables accurate determination of cardiac output. The method can be carried out in all patients without aortic stenosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Prolonged remission in Raynaud's phenomenon after prostacyclin infusion.

We infused prostacyclin (PGI2) (7.5 ng/kg/min) during 5 h, three times at weekly intervals in 8 patients with Raynaud's phenomenon (RP). In 4 patients, improvement was long-term, more than 90 days after the last infusion (good responders); in 3 patients, improvement was mild, less than 15 days, and in one patient no improvement was observed (poor responders). Clinical response was always accompanied by improvement, although less prolonged, of capillary appearance and/or function, as judged by microscopy and/or hemodynamic tests (pulse volume index; radial artery blood flow). Lastly, increased catabolism of PGI2 seemed to be excluded in poor responders, since no statistical difference in PGI2 metabolism could be observed between the two groups.

[Value of functional vascular study during endoluminal angioplasty in patients with obliterative arteriopathy of the legs]. / Intérêt de l'exploration fonctionnelle vasculaire au cours de l'angioplastie endoluminale chez des malades atteints d'artériopathie oblitérante des membres inférieurs.

Femoral blood flow, circulation time and arterial pressure at different levels, at rest and after a supervised treadmill test, were measured in 20 patients with obliterating arteriopathy of the lower limbs treated by percutaneous transluminal angioplasty (PTA), in a context of non-invasive vascular functional investigation. These haemodynamic parameters were measured pre-operatively, on the 1st post-operative day and in some case up to 18 months subsequently. Results on the whole were most satisfactory. In 18 patients, the haemodynamic improvement which was observed on the first post-operative day and confirmed by the clinical course persisted long after PTA; in one patient, with relapse of his haemodynamic signs, repeat angioplasty was carried out; another patient was referred for surgery after further clinical and haemodynamic deterioration. In the diagnosis and haemodynamic monitoring of patients with vascular stenoses, particularly those that have been treated by PTA, non-invasive functional investigation constitutes an important step, which is both effective and simple to carry out.