Regional and Conducted Vascular Effects of Endovascular Ultrasound Catheters.

Intra-vascular ultrasound catheters are used clinically to facilitate clot lysis. We hypothesized that these devices could also directly lower microvascular resistance and increase tissue perfusion through established shear-dependent pathways. In mice, either the proximal hind-limb muscles or the upstream femoral artery alone was exposed to an endovascular ultrasound catheter (2.3 MHz, 0.5-1.1 MPa) for 10 min. Quantitative microvascular perfusion imaging in the hind limbs exposed to the endovascular ultrasound system exhibited a more-than-twofold increase in flow (p < 0.01) compared with the contralateral control limb after exposure of either the muscle or the femoral artery alone. Using an in vivo optical imaging reporting system, an eight- to ninefold increase in tissue adenosine triphosphate (ATP) was detected in the region of insonification (p = 0.006). Ultrasound was found to produce an immediate release of ATP from ex vivo erythrocytes (p = 0.03). In situ electrochemical sensing revealed an immediate increase in nitric oxide with initiation of ultrasound which returned to baseline within 5 min of termination, as well as ultrasound-triggered nitric oxide (NO) release from erythrocytes. These data indicate that non-cavitating ultrasound produced by endovascular catheters can reduce vascular resistance and increase flow through recognized shear-dependent vasodilator pathways involving purinergic signaling and NO.

Valoración de la presión pulmonar y su repercusión sobre cavidades derechas por ecocardiografía / No disponible

El presente capítulo tiene como objetivo acercar al neumólogo el conocimiento de la ecocardiografía como herramienta fundamental para la estimación de parámetros hemodinámicos de indudable importancia para el agnóstico, la estratificación del riesgo y el manejo terapéutico de la hipertensión pulmonar (HTP) y el tromboembolismo pulmonar (TEP). En general, estas mediciones ecocardiográficas muestran una excelente correlación con la hemodinámica y los métodos empleados no son excesivamente complejos, estando al alcance de cualquier profesional con un tiempo de adiestramiento muy razonable. Este texto trata de explicar, de forma gráfica y sencilla, los distintos métodos empleados en ecocardiografía para cuantificar la presión pulmonar y las resistencias vasculares pulmonares. La ecocardiografía valora, además, las repercusiones que la HTP y el TEP ejercen sobre las cavidades derechas en su intento de adaptación, permitiéndonos analizar los principales parámetros de morfología y función ventricular derecha, que han demostrado tener un valor pronóstico en estas patologías

No disponible

Evaluation of effects of Extracorporeal Shock Wave Lithotripsy on renal vasculature with Doppler ultrasonography.

OBJECTIVES: In this prospective study, we aimed to demonstrate the effects of Extracorporeal Shock Wave Lithotripsy (ESWL) on renal blood flow in patients treated for renal/ ureteral stones. MATERIAL AND METHODS: The study group comprised 41 patients (26 males, 15 females, aged between 18-63 years, mean age 45 years), 23 with renal and 18 with ureteral stones, who underwent ESWL between March 2010 and January 2011. Colour Doppler ultrasonography and pulsed wave spectral analysis was performed before, 1 hour, and 7 days after ESWL to both ipsilateral and contralateral kidneys in order to measure resistive index (RI), pulsatility index (PI) and acceleration time (AT) values. RESULTS: One hour after ESWL, RI and PI values showed significant increase from pre-ESWL values in both ipsilateral and contralateral kidneys. However, no significant change was found in AT values. Seven days after ESWL, PI in both ipsilateral and contralateral kidneys and RI in contralateral kidney returned to pre-ESWL values. But, 7 days after ESWL, RI in the ipsilateral kidney did not return to pre-ESWL values, although decrease in RI values were observed. CONCLUSION: Spectral Doppler analysis can provide valuable information as a non-invasive method to assess the hemodynamic changes and renal microcirculation status in cases managed with ESWL.

Significant relationship between changes in brachial-ankle pulse wave velocity relative to blood pressure elevation and coronary artery disease.

OBJECTIVES: Based on well-established physiological theories, we studied correlations between changes in brachial-ankle pulse wave velocity (baPWV) relative to blood pressure (BP) elevation (elasticity of large-to-medium-sized arteries), and coronary artery disease (CAD). METHODS: The baPWV (in centimeters/second) and BP (in millimeters of mercury) were determined in 101 patients before, during, and/or after a cold pressor test using a volume-plethysmographic system. RESULTS: Significantly higher rates of increase in PWV relative to changes in BP were observed in the CAD(+) group than in the CAD(-) group when mean BP [median (25th-75th percentiles): 14.8 (8.3-24.9) vs. 8.6 (5.7-11.4) cm/s/mmHg, P<0.0001], and systolic [10.1 (6.0-17.5) vs. 6.4 (4.4-10.6) cm/s/mmHg, P=0.0023] and diastolic BP [21.0 (14.0-34.4) vs. 10.8 (6.8-16.1) cm/s/mmHg, P<0.0001] were used as BP indices. Similarly, the rates of increase in baPWV showed a significant correlation with the extent of CAD. The rate of increase in baPWV obtained using the mean, systolic and diastolic BP as indices showed an area under the receiver operating characteristic curve of 0.68-0.76, sensitivity of 65-75%, and specificity of 65-75% for the detection of CAD. The area under the receiver operating characteristic curve, sensitivity, and specificity for the rate of increase were slightly higher than those for baseline baPWV and baseline baPWV/baseline BP ratio, but not to a significant degree. CONCLUSION: The rate of increase in baPWV relative to BP elevation determined by cold pressor test is significantly and moderately correlated with CAD. To identify patients with CAD, the rate of increase in baPWV relative to changes in BP can provide considerable, but limited, information.

Arterial biomechanics after destruction of cytoskeleton by Cytochalasin D.

Vascular smooth muscle is a major structural element of the arterial wall. We examined the effects of cytoskeleton destruction, after administration of Cytochalasin D, on the biomechanical properties of porcine common carotids. Compared to untreated, maximally dilated controls, Cytochalasin D-treated arteries have shown a marked increase in compliance in the elastin-dominated pressure range. After weakening the VSM stress-bearing cytoskeleton by Cytochalasin D the artery would expand, reaching a new equilibrium state. This study brings further evidence that VSM is under tension, even when it is under zero load and at maximal vasodilation. This residual tension was released upon partial destruction of the cytoskeleton with Cytochalasin D. From a biomechanical standpoint, this means that the zero stress states of the in-series and parallel elastic components are substantially different.

Vascular injury after whole thoracic x-ray irradiation in the rat.

PURPOSE: To study vascular injury after whole thoracic irradiation with single sublethal doses of X-rays in the rat and to develop markers that might predict the severity of injury. METHODS AND MATERIALS: Rats that received 5- or 10-Gy thorax-only irradiation and age-matched controls were studied at 3 days, 2 weeks, and 1, 2, 5, and 12 months. Several pulmonary vascular parameters were evaluated, including hemodynamics, vessel density, total lung angiotensin-converting enzyme activity, and right ventricular hypertrophy. RESULTS: By 1 month, the rats in the 10-Gy group had pulmonary vascular dropout, right ventricular hypertrophy, increased pulmonary vascular resistance, increased dry lung weights, and decreases in total lung angiotensin-converting enzyme activity, as well as pulmonary artery distensibility. In contrast, irradiation with 5 Gy resulted in only a modest increase in right ventricular weight and a reduction in lung angiotensin-converting enzyme activity. CONCLUSION: In a previous investigation using the same model, we observed that recovery from radiation-induced attenuation of pulmonary vascular reactivity occurred. In the present study, we report that deterioration results in several vascular parameters for

Extracellular signal-regulated kinase (ERK) and protein kinase B (AKT) pathways involved in spinal cord stimulation (SCS)-induced vasodilation.

BACKGROUND AND AIMS: SCS is used to improve peripheral circulation in selected patients with ischemia of the extremities. However the mechanisms are not fully understood. The present study investigated whether blockade of ERK and AKT activation modulated SCS-induced vasodilation. METHODS: A unipolar ball electrode was placed on the left dorsal column at the lumbar 2-3 spinal segments in rats. Cutaneous blood flows from left and right hind foot pads were recorded with laser Doppler flow perfusion monitors. SCS was applied through a ball electrode at 60% or 90% of MT. U0126, an inhibitor of ERK kinase, or LY294002, an inhibitor of PI3K upstream of AKT, was applied to the lumbar 3-5 spinal segments (n=7, each group). RESULTS: U0126 (100 nM, 5 microM and 250 microM) significantly attenuated SCS-induced vasodilation at 60% (100 nM: P<0.05; 5 microM and 250 microM: P<0.01, respectively) and 90% of MT (100 nM and 5 microM: P<0.05; 250 microM: P<0.01, respectively). LY294002 at 100 microM also attenuated SCS-induced vasodilation at 60% and 90% of MT (P<0.05). CONCLUSIONS: These data suggest that ERK and AKT pathways are involved in SCS-induced vasodilation.

Effect of deep brain stimulation of the posterior hypothalamic area on the cardiovascular system in chronic cluster headache patients.

The objective of this study was to determine the cardiovascular effects of chronic stimulation of the posterior hypothalamic area (PHA) in cluster headache (CH) patients. Systolic and diastolic blood pressure (SBP, DBP), cardiac output, total peripheral resistance (TPR), heart rate (HR) and breathing were monitored at supine rest and during head-up tilt test (HUTT), Valsalva manoeuvre, deep breathing, cold face test and isometric handgrip in eight drug-resistant chronic CH patients who underwent monolateral electrode implantation in the PHA for therapeutic purposes. Autoregressive power spectral analysis (PSA) of HR variability (HRV) was calculated at rest and during HUTT. Each subject was studied before surgery (condition A) and after chronic deep brain stimulation (DBS) of PHA (condition B). Baseline SBP, DBP, HR and cardiovascular reflexes were normal and similar in both conditions. With respect to condition A, DBP, TPR and the LF/HF obtained from the PSA of HRV were significantly (P < 0.05) increased during HUTT in condition B. In conclusion, chronic DBS of the PHA in chronic CH patients is associated with an enhanced sympathoexcitatory drive on the cardiovascular system during HUTT.

Far-infrared therapy: a novel treatment to improve access blood flow and unassisted patency of arteriovenous fistula in hemodialysis patients.

Vascular access malfunction, usually presenting with an inadequate access flow (Qa), is the leading cause of morbidity and hospitalization in hemodialysis (HD) patients. Many methods of thermal therapy have been tried for improving Qa but with limited effects. This randomized trial was designed to evaluate the effect of far-infrared (FIR) therapy on access flow and patency of the native arteriovenous fistula (AVF). A total of 145 HD patients were enrolled with 73 in the control group and 72 in the FIR group. A WS TY101 FIR emitter was used for 40 min, and hemodynamic parameters were measured by the Transonic HD(02) monitor during HD. The Qa(1)/Qa(2) and Qa(3)/Qa(4) were defined as the Qa measured at the beginning/at 40 min later in the HD session before the initiation and at the end of the study, respectively. The incremental change of Qa in the single HD session with FIR therapy was significantly higher than that without FIR therapy (13.2 +/- 114.7 versus -33.4 +/- 132.3 ml/min; P = 0.021). In comparison with control subjects, patients who received FIR therapy for 1 yr had (1) a lower incidence (12.5 versus 30.1%; P < 0.01) and relative incidence (one episode per 67.7 versus one episode per 26.7 patient-months; P = 0.03) of AVF malfunction; (2) higher values of the following parameters, including Delta(Qa(4) - Qa(3)) (36.2 +/- 82.4 versus -12.7 +/- 153.6 ml/min; P = 0.027), Delta(Qa(3) - Qa(1)) (36.3 +/- 166.2 versus -51.7 +/- 283.1 ml/min; P = 0.035), Delta(Qa(4) - Qa(2)) (99.2 +/- 144.4 versus -47.5 +/- 244.5 ml/min; P < 0.001), and Delta(Qa(4) - Qa(2)) - Delta(Qa(3) - Qa(1)) (62.9 +/- 111.6 versus 4.1 +/- 184.5 ml/min; P = 0.032); and (3) a better unassisted patency of AVF (85.9 versus 67.6%; P < 0.01). In conclusion, FIR therapy, a noninvasive and convenient therapeutic modality, can improve Qa and survival of the AVF in HD patients through both its thermal and its nonthermal effects.

[Comparative characteristic of blood vessel filling and vascular tonus of microcirculation bed in patients with vasculo-autonomic dystonia and arterial hypertension, suffered as the result of accident on Chernobyl Atomic Electric Plant]. / Sravnitel'naia kharakteristika krovenapolneniia i tonusa sosudov mikrotsirkuliatornogo rusla pri vegetativno-sosudistoi distonii i arterial'noi gipertenzii u lits, postradavshikh vsledstvie avarii na ChAES.

Reliable difference of microvascular filling and microvascular tone of cerebral hemispheres and shins according to impedance tetrapolar plethysmography (rheoanalyzer PAS-01) data in patients with vegetovascular dystonia and arterial hypertension, suffered from Chernobyl accident was detected.

[Comparative characteristic of blood vessels filling, venous drainage and venous congestion in patients with autonomic vascular dystonia and arterial hypertention who have suffered from Chernobyl accident (according to the data of rheoencephalography and rheovasculagraphy)]. / Sravnitel'naia kharakteristika krovenapolneniia sosudov, venoznogo ottoka i venoznogo zastoia u bol'nykh s vegetativno-sosudistoi distoniei i arterial'noi gipertenziei, postradavshik vsledstvie avarii na ChAES (po dannym reoéntsefalo- i reovazografii).

Reliable differences in venous drainage and venous congestion and blood vessels filling of cerebral hemispheres in patients with vegetovascular dystonic and arterial hypertention who have suffered from Chernobyl accident have been detected by means of impedance tetrapolar plethysmography (rheoanalyzer PA5-01).

[Effect of vinpocetine on cerebral circulation in rats after exposure to radiation]. / Vliianie vinpotsetina na mozgovoe krovoobrashchenie u krys posle radiotsionnogo vozdeistviia.

Vinpocetine (5 mg/kg) increases the cerebral blood flow rate, retains autoregulation, and positively influences carbohydrate and transcapillary metabolism in rats upon single irradiation to a dose of 2 Gy.

[Effect of electromagnetic irradiation of the millimetric range on hemodynamics in patients with arterial hypertension]. / Vliianie élektromagnitnogo izlucheniia millimetrovogo diapazona na gemodinamiky u bol'nykh arterial'noi gipertoniei.

The study of efficacy of combined therapy including exposure to millimetric electromagnetic radiation (MER) in hypertensive patients has found a corrective hemodynamic effect of such treatment which appeared more potent than pharmacotherapy alone or combinations with sinusoidal modulated currents and placebo electromagnetic radiation. In hypokinetic and eukinetic types of hemodynamics MER raises cardiac output, lowers peripheral vascular resistance; in the hyperkinetic type there was a fall in the stroke and cardiac indices, compensatory rise of vascular resistance. The above changes in the course of treatment result in decline of both systolic and diastolic pressure and conversion of "extreme" types of hemodynamics in eukinetic in 11% patients. In hypertensive patients with eukinetic and hyperkinetic type of hemodynamics the best hemodynamic efficacy was achieved in combined therapy with 5.6 mm radiation.

Near-wall micro-PIV reveals a hydrodynamically relevant endothelial surface layer in venules in vivo.

High-resolution near-wall fluorescent microparticle image velocimetry (micro-PIV) was used in mouse cremaster muscle venules in vivo to measure velocity profiles in the red cell-depleted plasma layer near the endothelial lining. micro-PIV data of the instantaneous translational speeds and radial positions of fluorescently labeled microspheres (0.47 microm) in an optical section through the midsagittal plane of each vessel were used to determine fluid particle translational speeds. Regression of a linear velocity distribution based on near-wall fluid-particle speeds consistently revealed a negative intercept when extrapolated to the vessel wall. Based on a detailed three-dimensional analysis of the local fluid dynamics, we estimate a mean effective thickness of approximately 0.33 micro m for an impermeable endothelial surface layer or approximately 0.44 micro m assuming the lowest hydraulic resistivity of the layer that is consistent with the observed particle motions. The extent of plasma flow retardation through the layer required to be consistent with our micro-PIV data results in near complete attenuation of fluid shear stress on the endothelial-cell surface. These findings confirm the presence of a hydrodynamically effective endothelial surface layer, and emphasize the need to revise previous concepts of leukocyte adhesion, stress transmission to vascular endothelium, permeability, and mechanotransduction mechanisms.

[Effect of membrane-stabilizing magnetolaser therapy on cardiodynamics in patients with ischemic heart disease]. / Vliianie membranostabiliziruiushchei magnitolazernoi terapii na kardiodinamiku u bol'nykh ishemicheskoi bolezn'iu serdtsa.

AIM: To evaluate cardiodynamic changes in response to magnetolaser therapy (MLT) and these changes links with lipid shifts in cell membrane. MATERIAL AND METHODS: The study enrolled 50 patients with effort angina (functional class II-III). Of them, 37 patients were exposed to 10-day courses of MLT, 13 patients were exposed to sham procedures. Before the treatment and 3 months after it measurements were made of lipid peroxidation (LPO) products, structure of erythrocytic membrane and cardiodynamic parameters. RESULTS: MLT resulted in a significant reduction of LPO products, stabilization of cell membrane structure and positive shifts in cardiodynamics. Correlation was found between the above parameters. CONCLUSION: Improvement of inotropic, diastolic functions of the myocardium and abatement of cardiac remodeling in coronary heart disease patients in response to MLT is realized primarily due to structural stabilization of cell membrane lipid biolayer.

Ocular arterial blood flow of choroidal melanoma eyes before and after stereotactic radiotherapy using Leksell gamma knife: 2 year follow up.

AIMS: To evaluate the effect of high dose stereotactic radiotherapy on the ocular blood flow of patients with uveal melanoma. METHODS: Colour Doppler imaging (CDI) was used to measure blood flow velocity and vascular resistance in the ophthalmic, short posterior, and central retinal arteries of nine patients suffering from uveal melanoma. The measurements were taken before, 6 months, 1 year, and 2 years after stereotactic radiotherapy. Irradiation was performed with the Leksell gamma knife with the 59 (41-66.5) Gy total marginal dose divided in two equal fractions. CDI results were compared with age and sex matched healthy control eyes. RESULTS: At each time of measurement, blood flow velocity in the central retinal artery of the affected eyes was significantly reduced whereas vascular resistance was only increased at the 2 year follow up. Blood flow velocity and vascular resistance in the short posterior arteries of melanoma eyes were also only significantly altered at the 2 year follow up. Blood flow velocity and vascular resistance in the ophthalmic artery of melanoma eyes were not changed at all follow ups. CONCLUSIONS: In the melanoma eyes, blood flow velocity in the central retinal artery is reduced. High dose stereotactic radiotherapy with the Leksell gamma knife and a 59 (41-66.5) Gy total marginal dose in two fractions leads to a significant reduction of blood flow and a significant increase in resistance variables in the small ocular arteries within 2 years.

Value of uterine artery Doppler in endometrial cancer.

Twenty-seven women with endometrial cancer were studied with Doppler ultrasound coupled with a vaginal probe. Pulsatility index of the flow velocity of the uterine artery was recorded and compared to that of a control group. The subjects and the controls did not differ in blood flow measurements. There was no correlation between severity of disease and flow velocimetry values. Eleven of the patients underwent brachytherapy prior to surgery. Administration of brachytherapy resulted in a decrease of the peripheral resistance. The results of this study indicate that Doppler velocimetry of the uterine artery is not a valuable tool in discriminating between malignant and benign endometrium.

[Color doppler ultrasonography of uterine vessels during radiotherapy of advanced cervix cancers]. / Colordopplersonographische Untersuchungen uteriner Gefässe während der Radiotherapie fortgeschrittener Zervixkarzinome.

In tumor vessels of 14 patients with an advanced squamous cell carcinoma of the cervix uteri, an increase of the resistant index (RI) and the pulsatility index (PI) of tumor vessels was found later than the decrease of the volume of the tumor. For the uterine arteries these indices remained unchanged for patients with a complete remission, while for patients with incomplete remission there was a decrease of RI and PI.

A theoretical analysis of hemodynamic and biomechanical alterations in intracranial AVMs after radiosurgery.

PURPOSE: Stereotactic radiosurgery is being increasingly used to treat intracranial arteriovenous malformations (AVMs). However, successful radiosurgery may involve latent periods of 1-2 years prior to AVM obliteration. This latent period include states of altered flow patterns that may or may not influence hemorrhage probabilities. The probability of hemorrhage is likely to be related to the degree of biomechanical stress across the AVM shunt walls. This paper describes a theoretical analysis of the altered hemodynamics and biomechanical stresses within AVM shunts post-radiosurgery. METHODS AND MATERIALS: The mathematical model is comprised of linked flow compartments that represent the AVM and adjacent normal vasculature. As obliteration of the irradiated shunts occur, changes in flow rates and pressure gradients are calculated based on first order fluid dynamics. Stress on the AVM shunt walls is calculated based on tangential forces due to intramural pressure. Two basic models are presented: a distribution of shunts with fixed thin walls subject to step-function obliteration (Model I), and a distribution of shunts subject to luminal obliteration from slowly thickening walls (Model II). Variations on these models are analyzed, including sequential, selective and random shunt obliteration, and uniform or Poisson distributions of shunt radii. RESULTS: Model I reveals that the range of pressure alterations in the radiosurgically-treated AVM include the possibility of transient increases in the total biomechanical stress within the shunt walls prior to obliteration. Model II demonstrates that uniform luminal narrowing via thickened walls should lead to reduced transmural stresses. The precise temporal pattern of AVM flow decrease and biomechanical stress reduction depends on the selection of shunts that are obliterated. CONCLUSION: (a) The hemodynamic and biomechanical changes appear to be relatively independent of the shunt distribution but highly dependent on the temporal pattern of the obliterative process, (b) uniformly thickened shunt walls should uniformly decrease biomechanical stresses in the latent period prior to complete obliteration, but if uniform obliteration is not achieved, (c) transient alterations in pressure versus stress relationships may lead to temporarily increased biomechanical stress prior to complete obliteration, and (d) reduction in stress may not reach significant levels until the AVM is almost completely obliterated.

Resistance and pulsatility Doppler indices: how accurately do they reflect changes in renal vascular resistance.

Doppler indices such as the resistance (RI) and pulsatility indices (PI) are generally thought to indicate the resistance of the vascular bed supplied by the artery under investigation. However, this association remains uncertain; some studies have demonstrated an excellent correlation between alterations in vascular resistance and changes in Doppler indices, while others have shown no consistent change. In order to assess the validity of these two indices in estimating alterations in renal vascular resistance, 12 female Large White pigs, 45 weeks old, were entered into a double blind study. In nine of the pigs both kidneys received a single dose of 9.8 Gy 60Co gamma-rays; the remaining three served as sham-irradiated controls. Renal haemodynamics were measured using 131I-hippuran renography and Duplex Doppler prior to and at 8, and 12 weeks after kidney (sham-)irradiation. The sham-irradiated animals exhibited no significant changes in any of the parameters. In contrast, the animals in which both kidneys were irradiated exhibited a significant decrease (p < 0.001) in renal blood flow (RBF) 8 and 12 weeks after irradiation. In addition, both PI and RI were increased following kidney irradiation; however, this increase was not significant until 12 weeks after irradiation (p < 0.01). This suggests that the reduction in RBF was not simply a reflection of an increased vascular resistance and/or that PI and RI do not truly represent alterations in vascular resistance. Further studies are required to confirm the applicability of PI and RI in the assessment of renal haemodynamics.