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At least 55 records · Page 3Linked to original sources
PubMed1992

Atrial contractility affects phasic blood flow velocity of atrial small vessels in the dog.

OBJECTIVES: The aim was to evaluate the relative contribution of atrial muscle contraction and atrial pressure to the phasic patterns of left atrial arterial and venous flows. METHODS: Using a laser Doppler velocimeter, blood velocities were measured in the atrial small arteries and veins (outer diameter: 150-500 microns) in anaesthetised open chest dogs (n = 21). The velocity sensor was fixed on the vessel surface with a drop of cyanoacrylate glue when good quality Doppler signals were consistently observed. Left atrial pressure and the contractility of the left atrium were changed by premature ventricular contraction and by intracoronary injection of isoprenaline (0.5 microgram), respectively. RESULTS: Premature ventricular contraction increased left atrial pressure significantly during arterial velocity measurements from 8.1(SD 2.7) to 16.4(1.3) mm Hg and during venous measurements from 8.2(1.2) to 14.3(3.7) mm Hg. However, premature ventricular contraction did not change the blood velocity patterns, the maximum deceleration rate of the systolic velocity wave in arteries, or the maximum acceleration rate of the systolic velocity wave in veins. Although isoprenaline did not change the left atrial pressure, it decreased minimum arterial blood velocity during atrial systole, from 3.3(3.4) to -2.5(3.2) cm.s-1, and increased maximum venous blood velocity from 15.9(5.5) to 19.2(7.4) cm.s-1. Isoprenaline also increased both the maximum arterial systolic velocity deceleration rate, from 90(45) to 234(143) cm.s-2, and the maximum venous systolic velocity acceleration rate from 356(230) to 763(366) cm.s-2. CONCLUSIONS: (1) Left atrial pressure is not a major determinant of the blood flow patterns of the atrial arteries and veins, and therefore it may not closely reflect pressure around mural vessels. (2) Atrial contractility affects the blood flow patterns of the atrial arteries and veins.

Animals↗
PubMed1992

The circulation in the nipple-areola complex following subcutaneous mastectomy in breast cancer.

To evaluate the decrease in circulation in the nipple-areola complex after subcutaneous mastectomy and immediate implantation of a submuscular prosthesis, the blood flow was studied by both fluorescein flowmetry and laser Doppler flowmetry in 24 patients with invasive breast cancer. In 14 patients a lazy-S-shaped horizontal lateral incision was used, and 10 underwent a subcutaneous reduction mammaplasty. After subcutaneous mastectomy with a lazy-S incision there was no significant decrease in blood flow in the nipple-areola complex compared with that in the untreated contralateral breast. In the breasts in which reduction mammaplasty had been done, the blood flow was reduced by 74% as measured by fluorescein (p less than 0.01), and 70% by laser Doppler flowmetry (p less than 0.05), compared with the contralateral breast. Five patients had partial or complete epidermal, and one patient had total dermal, necrosis of the complex, but there was no deep necrosis. No fluorescence was seen within the areas in which necrosis later developed in any of these six cases. The laser Doppler signal in the corresponding areas, however, was not reduced. The results show that the circulation in the nipple-areola complex is reduced more after subcutaneous reduction mammaplasty than after subcutaneous mastectomy with a lazy-S incision.

Adult↗
PubMedDate not supplied

Design and evaluation of an instrument to measure microcirculatory blood flow and oxygen saturation simultaneously.

There are compelling clinical advantages in being able to monitor, simultaneously and continuously, blood oxygen saturation and tissue perfusion from the same volume of tissue. We describe the design of a new instrument capable of combining both functions. It uses a laser diode at 805 nm to give a blood flow index and oxygenation information at that wavelength, and a pulsed LED at 660 nm to complete the estimation of oxygen saturation. By using a compensating photodetector these readings can be made relatively insensitive to sampling site. After calibrating the instrument on forehead sites it reliably read the oxygen saturation of sites on the thigh with a bias of -0.2% and a precision of +/- 1.7% relative to an IL 282 CO-oximeter.

Calibration↗
PubMedDate not supplied

Oxford Optronix MPM 3S: a clinical assessment of a microvascular perfusion monitor.

The Oxford Optronix MPM 3S is a new microvascular perfusion monitor which is promoted as a device for use in the operating theatre. It uses a semiconductor laser diode and applies the Doppler principle to derive a semi-quantitative estimation of microvascular flow. We assessed this instrument with eight healthy volunteers who each performed eight different orthostatic arm manoeuvres while forearm skin blood flow was monitored. The different manoeuvres caused statistically significant changes in the instrument's reading which generally were consistent with expected changes in blood flow. The monitor also was assessed in the theatre environment with four anaesthetized patients. It proved easy to use, and was not subject to electrical interference from other equipment including short-wave diathermy. The major practical limitation of the technique is the semi-quantitative nature of the measurement. The instrument appears to have potential clinical uses in plastic and vascular surgery.

Adult↗
PubMedDate not supplied

Characteristics of laser Doppler flowmeters with differing optical arrangements.

Recently, various laser Doppler flowmeter (LDF) systems have been used for evaluation of tissue microcirculation. However, indifference has often been shown by doctors and researchers regarding their sampling volume, stability and accuracy, which differ with various optical arrangements. In this study we evaluated the characteristics of three LDF systems with different optical arrangements. The sampling depths in both blood and tissue were found to differ with the different optical arrangements, although the laser power emitted from the probes is nearly equivalent. Each depth significantly changed at haematocrits between 5.0 and 36.5%. The stability and the accuracy of the measurements also differed. In the practical case of tissue microcirculation it is important to measure blood flow with an understanding of the material differences in the characteristics of the LDF systems.

Animals↗
PubMedDate not supplied

Some flow visualization and laser-Doppler-velocity measurements in a true-to-scale elastic model of a human aortic arch--a new model technique.

Flow studies were done in an elastic true-to-scale silicone rubber model of an aortic arch to study further hemodynamic influences on atherosclerosis. The model was prepared from a cast of a young woman. A revised model technique was used. The model had a compliance similar to that of the human aortic arch. Velocity measurements were done in the model with a two component laser-Doppler-anemometer in steady and pulsatile flow using a calcium chloride solution with a viscosity of eta = 3.18 mPas and density of rho = 1.28 kg/m3 at 20 degrees C. The time average Reynolds numbers over a whole cycle in the ascending aorta was Re = 1350. The Womersley parameter for pulsatile flow was a = 20. The pulse wave velocity in the ascending aorta was about c = 5.4 m/sec. The secondary flow behavior was discussed for steady and pulsatile flow. Reverse flows were found, especially along the inner radius of the aortic arch in the descending aorta in steady and pulsatile flow and also in small areas of the ascending aorta and at the branches of the aortic arch. The formation of atherosclerotic plaques at preferred local flow regions is discussed.

Aorta, Thoracic↗
PubMed1992

Alterations of skin microcirculatory rhythmic oscillations in different positions of the lower extremity.

Microcirculatory vasomotion is considered to be an important mechanism promoting and facilitating the transfer of blood cells through skin capillaries. Since skin vulnerability of the leg is closely associated with gravitational factors and skin micro-circulation, we investigated by a laser Doppler apparatus influence of postural changes on skin blood flow oscillations in lower limbs of healthy volunteers. Our data show a marked decrease in microcirculatory oscillation amplitudes at a frequency 7.6 (+/- 0.6) min-1 after lowering the leg. This could be reversed by the application of compressive bandage. Our study points toward a potentially important mechanism of microcirculatory impairment during orthostasis.

Adult↗
PubMedDate not supplied

Comparison of heated-probe laser Doppler and transcutaneous oxygen measurements for predicting outcome of ischemic wounds.

Transcutaneous oxygen (TcPO2) measurement has proven to be an accurate means of predicting healing of ischemic wounds. This study compares the ability of TcPO2 and laser Doppler, modified by the addition of a heated probe (LDHP), to assess wound outcome. TcPO2 and LDHP measurements were made at the same site for 80 wounds, which consisted of 51 amputations (25 above knee, 6 below knee, 20 forefoot) and 29 ulcerations. Healing was defined as complete wound closure. Failure to heal was defined by the necessity for proximal amputation in 22 wounds (6 amputations, 16 ulcers). Outcome criteria were chosen to maximize accuracy and either positive or negative predictive values. Criteria with the greatest accuracy and positive predictive value for wound healing were > or = 11 mmHg for TcPO2 and > or = 50 mv for LDHP range. Criteria with the most appropriate accuracy and negative predictive value for wound failure were < 5 mmHg for TcPO2 and < 35 mv LDHP range. All wounds whose LDHP range was < 35 mv failed to heal, whereas some wounds with a TcPO2 of 0-1 mmHg healed successfully. An absolute prediction of wound healing (100% specificity and negative predictive value) was offered when either LDHP range was > or = 125 mv or TcPO2 was > or = 33 mmHg, although accuracy of either measurement at this criteria was unacceptable for more general application. We conclude that TcPO2 or LDHP will assess wound outcome with similar overall accuracy, although each test may be better for predicting a specific outcome.

Aged↗
PubMedDate not supplied

Cutaneous circulation in Raynaud's phenomenon during emotional stress. A morphological and functional study using capillaroscopy and laser-Doppler.

In order to assess the effects of emotional stress on the cutaneous microcirculation in patients suffering from Raynaud's phenomenon (RP) a group of 18 patients with this pathology and 16 healthy control subjects underwent an "arithmetical test". The microcirculatory response was examined using a laser Doppler apparatus. The results obtained showed a constantly reduced flow during mental stress in normal subjects; in the RP group it was possible to observe: a first subgroup with a reduced flow similar to that seen in normal subjects, and a second subgroup with a paradoxically increased flow. It is likely that the normal vasoconstrictor response is the expression of the functional impairment of the microcirculation alone (primary RP), whereas vasodilatation in response to mental stress is a sign, of the organic development of the disease right from an early stage.

Female↗
PubMedDate not supplied

Evaluation by captopril renal scintigraphy and echo-Doppler flowmetry of hypertensive patients at high risk for renal artery stenosis.

Sixty-three hypertensive patients with probability of obstructive renal artery disease underwent both Captopril renal scintigraphy (CRS) and echo-Doppler flowmetry (EDF) before undergoing renal angiography. Angiography revealed renal artery stenosis (RAS) in 42 patients (unilaterally in 26 and bilaterally in 16). The sensitivity and specificity in the identification of RAS > or = 50% were 90% and 94%, respectively for Captopril renography, and 85% and 78% for echo-Doppler flowmetry. Captopril renography correctly identified stenoses greater than 50%, which is usually held to be the limit of hemodynamic significance. While the Doppler examination was more sensitive than Captopril renography (sensitivity 79% versus 64%) in the detection of all degrees of RAS, less information on the functional significance of RAS was provided. Both CRS and EDF could be usefully employed to assess kidney perfusion, but their appropriate clinical use must take into account inherent differences between the two techniques.

Adolescent↗
PubMed1992

[Effects of biomicrosphere on the cochlear blood flow, blood pressure and heart rate in guinea pigs].

Cochlear blood flow (CBF) in guinea pigs was measured by Laser Doppler flowmeter and biomicrosphere method. The effects of dosages of biomicrospheres and time factor on the CBF, blood pressure and heart rate were observed. The findings suggest that 9 x 10(6). 10.5 x 10(6) biomicrospheres may be most suitable for measuring CBF with biomicrosphere method, and some physiological parameters of the guinea pig must be taken down within 2-10 minutes after microsphere injection.

Animals↗
PubMed1992

Intraoperative and postoperative monitoring of microsurgical free tissue transfers.

Numerous techniques have been described for monitoring the postoperative viability of microsurgical free tissue transfers, and their sensitivity and reliability continue to be evaluated in animal experiments and clinical trials. Relative advantages and disadvantages of these various postoperative monitoring techniques are discussed. The concept of intraoperative monitoring of the microsurgical anastomoses during closure and inset of a free flap is introduced because many free flaps may fail on the operating table, but this only becomes clinically apparent several hours later in the early postoperative period.

Animals↗
PubMed1992

[The effects of intracoronary injection of nitroglycerin on the coronary circulation: evaluation using a Doppler catheter].

To evaluate the effects of intracoronary injection of nitroglycerin (NTG) on the coronary circulation, we measured the flow velocity of the coronary artery using a Doppler catheter. The Doppler catheter was introduced into the region proximal to the left anterior descending artery (LAD) via an 8F guide catheter positioned at the orifice of the left coronary artery. We measured the flow velocity at a point of 3 mm distal to the catheter tip. One mg (2 ml) of NTG was injected via the 8F guide catheter for 10 sec, followed by injection of 3 ml of normal saline. Then the increasing rate of the diastolic coronary flow velocity in the LAD was calculated. Five ml of iopamidol (dye) was also injected for comparison. The subjects consisted of 14 normal persons (G-N), and 12 patients with angina pectoris accompanying critical stenoses of the LAD, who had no ECG changes or no abnormalities by left ventriculography. The subjects with angina pectoris were subclassified as 90% stenoses (G-A: 5 patients), and 99% stenoses (G-B: 7 patients) in the LAD. 1. After intracoronary injection of NTG, the aortic pressure dropped to various degrees in G-N. In 7 of the normal subjects, who had less than a 20% aortic pressure drop, the increased diastolic flow velocity was more rapid than the control diastolic flow velocity 30 sec after the peak velocity.(ABSTRACT TRUNCATED AT 250 WORDS)

Angina Pectoris↗
PubMedDate not supplied

[Clinical and instrumental evaluation of erectile impotence: a proposal of a diagnostic protocol].

There has been increasing interest in recent years in patients complaining of erectile dysfunction. This has prompted research and the development of diagnostic procedures aimed at allowing increasingly rapid characterization of the type of impotence involved (psychogenic or organic) and thus the most effective treatment. In this preliminary study, we present our study methodology in patients with erectile dysfunction, emphasising in particular the diagnostic procedures best suited to revealing the presence of an organic cause in the pathogenesis of impotence.

Erectile Dysfunction↗
PubMed1992

An experimental study on direct revascularization of bronchial circulation by microvascular anastomosis.

The effects of direct revascularization of the bronchial artery after bronchoplasty were estimated by laser Doppler velocimetry and india ink injection in dogs. Bronchoplastic surgery at the right main bronchus was performed in all dogs, and the bronchial artery was reconstructed using the internal thoracic artery in the reconstruction group. The mucosal blood flow was measured at the distal side of the anastomosis. India ink was injected into the aorta in the nonreconstruction group and into the internal thoracic artery in the reconstruction group. The peripheral blood flow had diminished immediately after surgeries to 59% of the baseline value and took 14 days to recover to the baseline value in the nonreconstruction group. However, in the reconstruction group, the blood flow recovered at once to 78% of the baseline value and had returned to that value in 5 days. Statistically significant differences were noted between the groups from just after operation to day 7. India ink data confirmed these findings. In the nonreconstruction group, no ink was observed in the peripheral bronchial vessels on day 3; it was noted in part of the vessels on day 7 and in most on day 14. On the other hand, a relatively large number of vessels were stained just after operation in the reconstruction group. Thus reconstruction of the bronchial artery by means of the anastomosis with the internal thoracic artery can be said to be a useful and effective method for preventing airway ischemia.

Anastomosis, Surgical↗
PubMed1992

[Preliminary study on the variability of the fetal cerebral velocimetry in various vessels of the Circle of Willis].

The authors have tried to analyse in a small series, the possibility as well as the variability of blood flow velocity waveforms in the different vessels of the circle of willis using colour Doppler. Fourteen patients were assessed. The 14 fetuses were of normal growth and/or had normal umbilical arterial blood flow velocity waveforms as well as normal uterine blood flow. The mean term at the time of examination was 23.8 +/- 2.9 standard deviation with the extremes going from 28.5 standard deviation to 40.5. The examinations were carried out using colour Doppler (Acuson) machine by the abdominal route with a 3.5-5 MHz bi-frequency sound. The vessels that were explored were the middle cerebral artery (CM), posterior cerebral artery (CP), the internal carotid artery (CI), the anterior cerebral artery (CA) in the region of the circle of Willis. CM and CA were able to be recorded in 100% of the cases, CP and CI in 93% of cases (13 out of 14 cases). The difference between he mean index (D/S, D = residual velocity in the diastole, S = maximum velocity in the systole) in each of these vessels was not statistically significant. In 3 out of 16 measurements (19%) the CP index was considered to be pathological while the index in the other vessels was normal, or when a different form of measurement was carried out in the region of CP, it was normal. This was also the case once for CA, but never for CM or CI.(ABSTRACT TRUNCATED AT 250 WORDS)

Artifacts↗