External Artery Diameter Research Articles

Pathophysiology of Vascular Stenosis and Remodeling in Moyamoya Disease.

Moyamoya disease (MMD) and moyamoya syndrome (MMS) are progressive vascular pathologies unique to the cerebrovasculature that are important causes of stroke in both children and adults. The natural history of MMD is characterized by primary progressive stenosis of the supraclinoid internal carotid artery, followed by the formation of fragile collateral vascular networks. In MMS, stenosis and collateralization occur in patients with an associated disease or condition. The pathological features of the stenosis associated with MMD include neointimal hyperplasia, disruption of the internal elastic lamina, and medial attenuation, which ultimately lead to progressive decreases in both luminal and external arterial diameter. Several molecular pathways have been implicated in the pathophysiology of stenosis in MMD with functions in cellular proliferation and migration, extracellular matrix remodeling, apoptosis, and vascular inflammation. Importantly, several of these molecular pathways overlap with those known to contribute to diseases of systemic arterial stenosis, such as atherosclerosis and fibromuscular dysplasia (FMD). Despite these possible shared mechanisms of stenosis, the contrast of MMD with other stenotic pathologies highlights the central questions underlying its pathogenesis. These questions include why the stenosis that is associated with MMD occurs in such a specific and limited anatomic location and what process initiates this stenosis. Further investigation of these questions is critical to developing an understanding of MMD that may lead to disease-modifying medical therapies. This review may be of interest to scientists, neurosurgeons, and neurologists involved in both moyamoya research and treatment and provides a review of pathophysiologic processes relevant to diseases of arterial stenosis on a broader scale.

Pregnancy-induced long-term uterine vascular remodeling in the rat

Despite the available research investigating uterine physiology during and immediately following pregnancy, including at the vascular and muscular levels, knowledge of the potential long-term timeline of such changes is limited. Thus, our study sought to investigate the potential long-term changes in uterine vasculature and horn length in the postpartum rat, following delivery and weaning. Female Long-Evans rats (n = 9–11 rats/group/timepoint) were divided into two groups: a pregnant group and an age-matched virgin control group. Rat weight, food consumption and vaginal impedance measurements were recorded throughout the experiment. Rats in the pregnant group were bred and pregnancy was confirmed using ultrasound imaging. The uterus and its vasculature were collected at various timepoints following weaning: 3 (week of weaning), 8–9 and 13 weeks postpartum, and at age-equivalent timepoints in the virgin group, and the diameters of the main uterine artery and vein, and lengths of the mesometrial segmental vessels (MSV) and uterine horns were recorded. The results indicated a significant difference between the previously-pregnant and virgin rats in both internal and external arterial diameters (but not arterial wall thickness), as well as the uterine horn length, 3 weeks postpartum, but not 8–9 and 13 weeks postpartum. Significant differences were observed in both venous diameter and MSV length at all timepoints measured. Placental scars were also observed in previously-pregnant rats at all timepoints measured. Our study highlights the long-term impact of pregnancy on the uterine vasculature and the necessity for consideration of such changes on subsequent pregnancies, as well as pregnancy-related vascular pathologies.

CT angiography with 15 mL contrast material injection on time-resolved imaging for endovascular abdominal aortic aneurysm repair

PurposeTo assess the utility of whole-aorta CT angiography (CTA) with 15 mL contrast material (CM) on time-resolved imaging for endovascular abdominal aortic repair (EVAR). MethodsTwenty-six patients with a high-risk of post-contrast acute kidney injury (PC-AKI) underwent CTA with 15 mL CM using temporal maximum intensity projection (tMIP-CTA) generated from time-resolved imaging. The aortoiliac CT values were measured. Two observers measured the arterial diameters in unenhanced CT and tMIP-CTA images, and image quality was evaluated on a 5-point scale. The presence of the accessory renal artery, inferior mesenteric artery (IMA) occlusion, and instructions for use (IFU) of EVAR were evaluated. ResultsCT examinations were successfully performed, and no patients developed PC-AKI. The mean CT values of the whole aorta were 267.5 ± 51.4 HU, which gradually decreased according to the distal levels of the aorta. Bland-Altman analysis revealed excellent agreement for the external arterial diameter measurements between unenhanced CT and tMIP-CTA. Excellent interobserver agreement was achieved for the measurements of the external (ICCs, 0.910–0.992) and internal arterial diameters (ICCs, 0.895–0.993). Excellent or good overall image quality was achieved in 24 (92 %) patients. The presence of the accessory renal artery, IMA occlusion and the assessment of IFU were in 100 % agreement. Multivariate analysis revealed aortic volume as the most significant independent factor associated with strong aortic enhancement (p = 0.004). ConclusionsWhole-aorta tMIP-CTA on time-resolved imaging is useful for maintaining contrast enhancement and image quality for EVAR planning, and can substantially reduce the amount of CM.

P3581Periinterventional cocoa flavanol supplementation prevents functional and structural damage to the arterial wall after transradial catheter intervention

Abstract Background The transradial approach is commonly preferred over the femoral approach for coronary angiography to reduce vascular complications like bleeding, aneurysm formation and all-cause mortality ensuring early ambulation after coronary procedures. However, there is growing evidence that damage to the radial artery endothelium elicits intimal hyperplasia, vascular remodeling and might ultimately lead to total vessel occlusion. Objective Our study aimed to investigate the effects of dietary flavanol intervention on (a) early endothelial functional recovery and (b) late structural changes i.e. intimal hyperplasia after mechanical vascular wall injury in the human forearm model during coronary angiography. Methods Radial artery flow-mediated vasodilation (RA-FMD), local stiffness (fractional diameter change, Fdc), intima-media thickness (IMT), luminal and external arterial diameter at the site of intervention and the contralateral control artery were measured in 38 male patients (19 flavanol intervention, 19 placebo control) undergoing transradial coronary angiography (TCA) at baseline, after 7 days of 450mg flavanol supplementation BID, directly after TCA and 6 months after TCA. Circulating levels of endothelial microparticle (EMP) subpopulations CD31+/41-, CD62e+and CD144+were analyzed simultaneously as a surrogate for endothelial functional integrity and activation. Results One week of flavanol supplementation, not placebo, significantly increased RA-FMD (8.88±2.03% vs. 11.17±2.89%, p<0.01 in flavanol and 8.64±1.87% vs. 8.32±1.63%, p=n.s. in placebo). RA-FMD significantly decreased in the intervention artery directly after TCA, which was partly mitigated by flavanol supplementation (delta to baseline: −2.61±0.82% in flavanol vs. −4.91±0.63% in placebo, p=0.034). TCA induced significant intimal hyperplasia in the radial artery (0.36±0.02mm vs. 0.44±0.04mm, p<0.01) in placebo, but not in the flavanol group (0.36±0.02mm vs. 0.37±0.02mm, p=n.s.) after 6 month. One week of flavanol supplementation increased Fdc (1.94±0.99 vs. 3.07±1.31, p<0.01). No changes occurred in the placebo group (1.99±1.29 vs. 1.96±1.17, p=n.s.). On the contralateral arm, the decrease in RA-FMD was blunted by flavanols (delta to baseline: +0.42±1.05% in flavanol vs. −0.61±1.55% in placebo) along with decreased circulating levels of EMPs. Conclusions TCA impairs endothelial function (RA-FMD), vascular physicomechanics (Fdc) and induces intimal hyperplasia (IMT). Periinterventional flavanol supplementation blunts the acute decreases in endothelial function and physicomechanics and prevents chronic negative vascular remodeling.

Effect of botulinum toxin type A injection in the viability of dorsal flap in rats

Purpose: Botulinum toxin A (BoNTA) increased the viability of skin flap in healthy rats. Most of the studies injected this substance some days (7-15) before the flap surgery. This treatment is used only for elective surgery, there was no data about the efficacy of BontA when injected in the surgical period. This study aimed to analyze the effect of BontA on the viability of Random flap in a intra surgical injection. Methods: Twenty male Wistar rats (250–300 g) were randomly divided into four groups: saline injection 15 days prior the surgery (G1), BoNTA injection 15 days prior the surgery (G2), saline injection intraoperative period (G3), BoNTA injection intraoperative (G4). A dorsal cutaneous flap (3×10cm) was performed. Survival area and total area of the flaps were measured. Lumen diameter, external arterial diameter and lumen/wall thickness ratio were recorded. Results: Viable area increased in Bonta 15days group when compared to saline-15days (1080.7 ± 307.5 mm2 vs. 1594.5 ± 419.7mm2, p= 0.01) and in the Bonta –intraoperative injection when compared to saline intraoperative injection (1133.3 ± 462.0 mm2 vs. 1389.9 ± 320.4 mm2, p=0.014). The ratio viable area/total area showed similar results (G1 versus G2, 0.43 vs. 0.74; p<0.001, respectively) and G3 versus G4 (0.44 vs. 0.61 p= 0,04). We did not find any difference in the microscopic analysis (lumen diameter, external arterial diameter and lumen/wall thickness ratio). Conclusion: BoNTA injected fifteen days before the surgery increased skin flap viability. However, BontA injected intraoperatory time did not increased the flap viability.

Current smoking aggravates intimal hyperplasia after arterial injury following transradial catheterization

Objectives: The aim of the study was to investigate the effect of current smoking on long term arterial structural remodeling processes after arterial injury induced by transradial coronary angiography (TCA). Background: Cigarette smoking is the most important modifiable cardiovascular risk factor, leading to endothelial dysfunction, and delayed recovery of endothelial function after arterial injury. Methods: We recruited 50 patients, 59±10 years, undergoing TCA with a transradial access (5-F) that were current smokers (n=21) or had quit smoking >1 year prior to TCA (n=29). In a first series (n=10), we investigated the time course of radial artery endothelial function by flow-mediated vasodilation (FMD) up to 72 h after TCA. In a second series (n=40), we investigated long term arterial thickening as intima-media thickness (IMT), luminal and external arterial diameter, and fractional diameter change (FDC) along with FMD at >1 month after TCA. The contralateral radial artery served as a control. Results: Current smokers exhibited significantly lower FMD at baseline (8.0±0.9% vs 9.5±0.7%, p=0.016) and decreased to similar values at 6 h after TCA (4.1±1.6% vs 4.8±1.6%, p=0.479). Whereas in former smokers' radial artery FMD had returned to baseline at 24 h, smokers remained impaired at 24 h and recovered at 48 h (7.8±1.1% vs. 9.8±0.8%, p=0.009). At later time points (9.7±2.9 months), FMD was not changed. Overall, the IMT of the intervention arm was significantly thicker (0.40±0.07 mm vs 0.31±0.06 mm, p<0.01) and FDC (6.7±4.6% vs 2.8±3.5% p<0.01) lower as compared to the control arm. Subgroup analysis revealed that smoker's IMT thickening was significantly greater as compared to former smokers (0.45±0.06 mm vs. 0.37±0.05 mm, p=0.001), the outside diameter was significantly greater (2.95±0.32 mm vs. 2.71±0.33 mm, p=0.048), at similar luminal diameters (2.02±0.34 mm vs. 2.12±0.36 mm, p=0.072), and the FDC was significantly lower (5.4±3.7% vs. 2.3±1.2%, p=0.029) suggesting accelerated arterial thickening and stiffening. Values for IMT correlated with cigarette consumption within 24 h of TCA (r=0.62, p<0.001). Control arm measurements were not different between groups. Conclusion: Our data suggest that current smoking status strongly impacts on the recovery of endothelial function and structural maintenance of arteries following arterial injury potentially interfering with vascular repair mechanisms. Therefore, enforcement of peri-interventional smoking abstinence may help to prevent intimal hyperplasia.

P51: Current smoking aggravates intimal hyperplasia after arterial injury following transradial catheterization

Objectives The aim of the study was to investigate the effect of current smoking on long term arterial structural remodeling processes after arterial injury induced by transradial coronary angiography (TCA). Background Cigarette smoking is the most important modifiable cardiovascular risk factor, leading to endothelial dysfunction, and delayed recovery of endothelial function after arterial injury. Methods We recruited 50 patients, 59 ± 10 years, undergoing TCA with a transradial access (5-F) that were current smokers (n = 21) or ex-smokers that had quit smoking >1 year prior to TCA ( n = 29). In a first series ( n = 10), we confirmed the time course of endothelial functional recovery up to 72 h following TCA by flow-mediated vasodilation (FMD) of the radial artery. In a second series ( n = 40), we investigated long term arterial remodeling at the site of TCA injury by intima-media thickness (IMT), luminal and external arterial diameter, and fractional diameter change (FDC) along with FMD at 9–12 months after TCA. The contralateral radial artery served as a control. Results Current smokers exhibited significantly lower radial artery FMD at baseline (8.0 ± 0.9% vs. 9.5 ± 0.7%, p = 0.016) and decreased to similar values at 6 h after TCA (4.1 ± 1.6% vs. 4.8 ± 1.6%, p = 0.479). Whereas in former smokers’ radial artery FMD had returned to baseline at 24 h, smokers’ FMD remained impaired at 24 h and only recovered at 48 h (7.8 ± 1.1% vs. 9.8 ± 0.8%, p = 0.009); at a mean follow-up of 9.7 ± 2.9 months, FMD was not different from baseline values. However, significant structural changes were detectable at the vascular access site with IMT in the intervention arm thicker (0.40 ± 0.07 mm vs. 0.31 ± 0.06 mm, p p p = 0.001), the outside diameter was significantly greater (2.95 ± 0.32 mm vs. 2.71 ± 0.33 mm, p = 0.048), at similar luminal diameters (2.02 ± 0.34 mm vs. 2.12 ± 0.36 mm, p = 0.072), and the FDC was significantly lower(5.4 ± 3.7% vs. 2.3 ± 1.2%, p = 0.029) indicating more pronounced arterial stiffening and positive remodeling in current smokers. Values for IMT correlated with cigarette consumption within 24 h of TCA ( r = 0.62, p Conclusion Our data suggest that current smoking status strongly impacts on the recovery of endothelial function and structural maintenance of arteries following arterial injury potentially interfering with vascular repair mechanisms. Therefore, enforcement of peri-interventional smoking abstinence may be necessary to allow optimal regeneration. Disclosure Nothing to disclose.

Clinical course of homozygous familial hypercholesterolemia during childhood: report on 4 unrelated patients with homozygous or compound heterozygous mutations in theLDLR gene

Natural history of the disease in 4 unrelated Polish children with homozygous familial hypercholesterolemia (FH) is described. Their phenotypic homozygosity was established by identification of known LDLR gene mutations on both alleles, respectively: p.G592E & p.G592E in Patient 1; p.G592E & p.C667Y in Patient 2; p.S177L & p.R350X in Patient 3; and p.G592E & deletion in the promoter region, exons 1 and 2 in Patient 4. Heterozygosity of the mutations was revealed in all patients' mothers and fathers (obligatory heterozygotes) and in 1 out of 4 siblings studied. FH was diagnosed at the age of 4 months to 9 years by cholesterol screening among family members of patients with early cardiovascular disease episodes. At the time of FH detection, the children were asymptomatic. Only in 2, some skin eruptions were found. Antihyperlipidemic therapy was started, including a lipid-lowering diet, cholestyramine, and HMG-CoA inhibitors if necessary. No cardiovascular symptoms appeared during the observation up to the age of 18, 20, 19, and 17 years, respectively. An increase in external carotid artery diameter was found in a patient at the age of 9 years, and LDL-apheresis was introduced in his therapy. We conclude that the analysis of LDLR gene mutations in the studied FH children made it possible to identify 4 presymptomatic FH homozygotes and to introduce early appropriate treatment. Multicenter analysis of such persons would finally determine if the early lipid-lowering procedures can significantly reduce the risk of premature cardiovascular disease in homozygous FH.

The Segmental Pectoralis Major Free Flap

The pectoralis major muscle may be suited for free transplantation of a segment of the muscle. We investigated the length and diameter of its vascular pedicle to determine its feasibility. The length of the pedicle, its arterial diameter, and its entry point into the muscle were determined in 17 cadaveric flaps. The pedicle length up to the medial border of the pectoralis minor muscle averaged 6.6 cm. The mean external arterial diameter was 1.8 mm, and the venous diameter was consistently larger. The vascular pedicle consistently entered the muscle lateral to the midpoint of, and a mean of, 8.8 cm caudal to the clavicular line. The vascular length and diameter are sufficient for microvascular anastomosis. Although an anatomic landmark for the cranial border of the flap could not be defined, the sternocostal part of the pectoralis major muscle may potentially be used as a segmental free flap.

Morphology of the Internal Elastic Lamina in Arteries from Pulmonary Hypertensive Patients: a Confocal Laser Microscopy Study

The development and progression of pulmonary hypertension lesions involve continuous remodeling of the arterial wall, including the extracellular matrix components. The integrity of the internal elastic lamina may represent a barrier to cell migration and formation of intimal proliferative lesions. Some patients with congenital cardiac shunts develop precocious intimal occlusive lesions,whereas others evolve with isolated medial hypertrophy. We studied the 2-D and 3-D morphology of the internal elastic lamina of peripheral pulmonary arteries to search for any difference regarding the type of histological lesion. Fifteen lung biopsies collected for diagnostic purposes from patients with congenital shunts and 6 control lungs (mean ages, 15.8 and 14.7 mo) were studied using the confocal laser scanning microscope, under predetermined conditions of laser intensity, brightness and contrast. We measured the thickness of the internal elastic lamina and determined the number of gaps and projections of elastic tissue towards the medial and intimal layers. The mean internal elastic lamina thickness was significantly higher in arteries from cases with isolated medial hypertrophy when compared with controls and to those with proliferative lesions (P < .05). The number of gaps of the internal elastic lamina was higher in arteries >100 μm in diameter from the group with intimal lesions when compared to the cases presenting with isolated hypertrophy, but did not differ from the controls. There was a positive linear correlation between the external arterial diameter and the thickness of the internal elastic lamina (r = .74, P < .001) in cases presenting isolated medial hypertrophy. The increased thickness and smaller number of gaps of the internal elastic lamina may act as a barrier that prevents smooth muscle cell migration in patients with pulmonary hypertension without intimal proliferative lesions. On the other hand, a greater number of gaps does not represent, by itself, unrestrained migration, because controls also showed fenestrated laminae.

Arterial wall properties and Womersley flow in Fabry disease.

Fabry disease is an X-linked recessive lysosomal storage disease resulting in the cellular accumulation of globotriaosylceramide particularly globotriaosylceramide. The disease is characterized by a dilated vasculopathy with arterial ectasia in muscular arteries and arterioles. Previous venous plethysomographic studies suggest enhanced endothelium-dependent vasodilation in Fabry disease indicating a functional abnormality of resistance vessels. We examined the mechanical properties of the radial artery in Fabry disease, a typical fibro-muscular artery. Eight control subjects and seven patients with Fabry disease had a right brachial arterial line placed allowing real time recording of intra-arterial blood pressure. Real time B-mode ultrasound recordings of the right radial artery were obtained simultaneously allowing calculation of the vessel wall internal and external diameter, the incremental Young's modulus and arterial wall thickness. By simultaneously measurement of the distal index finger-pulse oximetry the pulse wave speed was calculated. From the wave speed and the internal radial artery diameter the volume flow was calculated by Womersley analysis following truncation of the late diastolic phase. No significant difference was found between Fabry patients and controls for internal or external arterial diameters, the incremental Young's modulus, the arterial wall thickness, the pulse wave speed and the basal radial artery blood flow. Further, no significant difference was found for the radial artery blood flow in response to intra-arterial acetylcholine or sodium nitroprusside. Both drugs however, elevated the mean arterial flow. The current study suggests that no structural or mechanical abnormality exists in the vessel wall of fibro-muscular arteries in Fabry disease. This may indicate that a functional abnormality downstream to the conductance vessels is the dominant feature in development Fabry vasculopathy.

In vitro diameter response of rat femoral artery to flow in the presence and absence of endothelium

We have examined the diameter response of rat femoral artery segments in the presence and absence of endothelium to changes in flow rate. The segments were isolated, mounted on microcannulae, maintained at 37°C, and perfused at 90 mmHg with Tyrode's solution. The external arterial diameter was measured using video-microscopy. The mean control diameter was 741±22 μm (mean±SEM, n=7). The arteries were preconstricted to 75±1% of the control diameter with a superfusion of 1 μM norepinephrine (NE). Endothelial function was verified by perfusion of 1 μM acetylcholine (ACh). Two different flow protocols were employed: step changes in flow ( n=7) and low-frequency sinusoidal flow changes ( 0.01 Hz <f<0.05 Hz ,n=3 ). The endothelium was then removed by perfusion of the artery with 0.3% CHAPS ( n=7) and the flow protocol repeated. All arteries contracted with increasing flow. For rapid step changes in flow, contractions and relaxations were modelled with an exponential fit where characteristic time constants were 34±2 and 40±3 s, respectively (functional endothelium) and 35±2 and 37±2 s, respectively (non-functional endothelium). The time constants in the presence and absence of endothelium were not significantly different (paired t-test, p>0.05). Sinusoidal flow oscillations resulted in sinusoidal diameter oscillations, whose amplitude and phase lag were inversely proportional to the frequency of the flow oscillations. A first-order low-pass filter, with a time constant of 28±3 and 30±5 s for arteries with and without functional endothelium, respectively, was used to describe the relation between oscillatory flow and diameter. The response of the rat femoral arteries to changes in flow was not found to be different whether the endothelium was intact or removed.

Comparative effects of frovatriptan and sumatriptan on coronary and internal carotid vascular haemodynamics in conscious dogs.

The effects of frovatriptan and sumatriptan on internal carotid and coronary vascular haemodynamics were investigated and compared in conscious dogs. Frovatriptan and sumatriptan (0.1 - 100 microg kg(-1)) induced a transient increase in external coronary artery diameter (eCOD) of up to 2.9+/-1.2 and 1.8+/-0.6%, respectively (both P:<0.05). This was followed by a prolonged and dose-dependent decrease in eCOD of up to -5.2+/-1.2 and -5.3+/-0.9% (both P:<0.05), with ED(50) values of 86+/-21 and 489+/-113 micromol kg(-1), respectively. In contrast, only a decrease in the external diameter of the internal carotid artery was observed (-6.0+/-0.6 and -6.2+/-1.4%, both P:<0.05, and ED(50) values of 86+/-41 and 493+/-162 micromol kg(-1), respectively). Frovatriptan was thus 5.7 fold more potent than sumatriptan at the level of both large coronary and internal carotid arteries. After endothelium removal by balloon angioplasty in coronary arteries, the initial dilatation induced by the triptans was abolished and delayed constriction enhanced. The selective antagonist for the 5-HT(1B) receptors SB224289 dose-dependently blocked the effects of sumatriptan on large coronary and internal carotid arteries whereas the selective antagonist for the 5-HT(1D) receptors BRL15572 did not affect any of these effects. In conclusion, frovatriptan and sumatriptan initially dilate and subsequently constrict large coronary arteries in the conscious dog, whereas they directly constrict the internal carotid artery. The vascular endothelium modulates the effects of these triptans on large coronary arteries. Finally, 5-HT(1B) but not 5-HT(1D) receptors are primarily involved in canine coronary and internal carotid vasomotor responses to sumatriptan.

DIAMETROS DE LAS ARTERIAS CEREBELAR SUPERIOR Y CEREBELAR ANTERIOR-INFERIOR EN EL SEGMENTO PONTINO-ANTERIOR

At present, the clinical specialized literature, insist in the necessity of an anatomical precise knowledge, necessary for the success in neurochirurgical interventions during the approaching to the posterior cranial fossa. Based in previous reports, we have made an anatomical revision of the superior cerebellar artery and anterior inferior cerebellar artery focused to its anterior pontine segments with data that may contribute to their study and that they could be of practical useful. This study was done in 70 brains of brazilian adult cadavers, from both sexes, collected at the Anatomy Laboratory Sao Paulo Medical School / UNIFESP (Sao Paulo, Brazil), and to which them, we registred their anthropological data. It was considered the cephalics measurements too. We took the brains from skulls, using established anatomical techniques and inyected its vascular system with red collored neopren latex and fixed into a 10 % formaldehyde solution. At right side, masculine sex, the external diameter of superior cerebellar artery was 2.0 to 2.9 mm in range in 66.7% of the cases, and in the feminine sex in 82.1%; in 75.0% in dolicho-mesocephalics and 71.1% in the brachycephalics. The anterior inferior cerebellar artery external diameter at right side, masculine sex, this range of 1.0 to 1.5 mm was observed in 50% of the cases, the same porcentagem was registred in the feminine sex; in 53.1% in the dolicho-mesocephalicsand; in 47.4% in the brachycephalics. The authors insists in the variability observed in the patterns, upon taking in consideration, besides the side and sex, other parameters suchs as the cephalic index, that they are important in the face of the evident heterogeneity of our indoamerican populations

Effects of Cryopreservation on the Viscoelastic Properties of Human Arteries

The purpose of this study was to use our newly developed mock circulation loop to determine the effects of cryopreservation on the common carotid artery (CCA) and the superficial femoral artery (SFA). Fourteen healthy arteries (7 CCA and 7 SFA) harvested from multiple organ donors between the ages of 18 and 35 years were tested before and after cryopreservation at -140 degrees C using dimethyl sulfoxide and the vapor phase of liquid nitrogen. Mean storage time was 4.2 months. The mock pulse rate was 60 beats/min and the following four systolic/diastolic pressures settings were used: 50/110, 80/140, 110/170, and 140/200 mm Hg. Simultaneous measurements of intra-arterial pressure and external arterial diameter were made using an intra-arterial pressure sensor and external piezoelectric sensors. Measured data were used to calculate pulsatility, volumetric compliance, stiffness, midwall radial arterial stress, Young's modulus, and the incremental modulus. After SFA cryopreservation, no significant changes were observed. Conversely, CCA cryopreservation led to a significant decrease in compliance and pulsatility and a significant increase in stiffness. Young's modulus, the incremental modulus, and midwall radial arterial stress did not change significantly. A clearcut decrease in hysteresis was observed after cryopreservation in the CCA. No evidence of structural changes was detected on light and scanning electron microscopy. Baseline findings in this study were consistent with classification of the CCA as an elastic artery and the SFA as a muscular artery. Cryopreservation had no effect on the viscoelastic properties of muscular arteries (SFA). Cryopreservation affected only values related to the cylindrical shape of the elastic arteries (CCA). It had no effect on values related to wall structure.

Myogenic response of isolated pressurized rabbit ear artery is independent of endothelium

Central ear artery segments, removed from urethan-anesthetized rabbits, were used to assess whether distention activation was dependent on intact and functional endothelium (ENDO). Changes in external arterial diameter were measured with light-dependent diode array mounted above the vessel. After constriction with norepinephrine, slow increases in pressure from 60 to 80 or 100 mmHg performed over 120 s (pressure ramps) failed to initiate distention, but initial diameter was maintained. Rapidly applied (500 ms) pressure increases (pressure jumps) across same pressure ranges gave rise to initial distention and a myogenic response resulting in a return to almost initial diameter while new pressure was maintained for 120 s. Myogenic activity was measured from extent of recovery of vessel to its initial diameter during maintenance of pressure jumps or ramps. Rapid jumps and slow ramps were performed in presence of an intact ENDO and again after ENDO was removed by passage of intraluminal gas. With pressure jumps 60 to 80 mmHg, degree of recovery in ENDO-denuded vessels was 91.9% compared with 89.5% in ENDO intact vessels. For pressure jumps 60 to 100 mmHg, extent of recovery was 87.4 and 89.6%. During application of pressure ramps of 20 or 40 mmHg, vessel diameter did not increase by greater than 5%. There are no significant differences in these data, and we conclude that myogenic response in rabbit ear artery is mediated independently of endothelial-derived factors, irrespective of whether myogenic activation is induced by pressure jumps or ramps.

Cor Pulmonale: Correlation with Central Airway Lesions, Peripheral Airway Lesions, Emphysema, and Control of Breathing

We have analyzed the heart and lung findings in 31 patients in the National Institutes of Health (NIH) Nocturnal Oxygen Therapy Trial (NOTT) with particular emphasis on cor pulmonale. Increased right ventricular weight was related to decreased bronchiolar diameter, decreased ratio of bronchiolar diameter to external arterial diameter, and an increased proportion of airways less than 400 microns in diameter. No relationship was found between the severity of emphysema, mucous gland enlargement, peripheral airway mucous plugging, or other measurement of central and peripheral airways. Patients with right ventricles weighing more than 100 g had higher pulmonary artery pressures at rest and higher arterial CO2 levels than those weighing 100 g or less. When the patients were divided into Types A, B, and X according to Burrows' criteria, those with Type X had a higher volume proportion of mucous glands; type B were intermediate; and Type A had the smallest. The amount of bronchial muscle was less in Type B patients than in Type A, and right ventricles weighted less in Type A patients than in Type B. Hypoxic ventilatory drive was lower in Type B patients than in Type A. Absolute right ventricular weight appeared to be a better measurement of right ventricular enlargement than relative right ventricular weight in the NIH NOTT patients. We conclude that right ventricular weight in patients with hypoxic chronic airflow obstruction (CAO) is related to airway narrowing, and that the Type B syndrome is associated with decreased ventilatory drive.

Myogenic Tone of the Rat Testicular Subcapsular Artery has a Role in Autoregulation of Testicular Blood Supply

An in vitro method is described for the isolation, cannulation, and pressurization of a 10-mm segment of the adult rat testicular subcapsular artery by use of a 200-microns micropipette connected to an adjustable-height reservoir. External and internal arterial diameters were measured by a digital filar micrometer eyepiece calibrated with a Microcode scaler. Transmural pressure was increased stepwise by 20 mm Hg from 20 to 180 mm Hg at 10-min intervals. The following novel triphasic myogenic response was found: a 22.5% increase in lumen cross-sectional area from 20 to 40 mm Hg (p less than 0.05); a 37.3% decrease in lumen cross-sectional area from 40 to 100 mm Hg (p less than 0.05); and a 72.4% increase in lumen cross-sectional area from 100 to 180 mm Hg (p less than 0.05). Papaverine (0.1 mM) completely blocked the transmural pressure-induced vasoconstriction, indicating an active increase in vascular smooth muscle tone by transmural pressure. The calculated blood flow through the testicular subcapsular artery of the adult rat, from measured internal radii at various transmural pressures ranging from 20 to 180 mm Hg by Poiseuille's equation, was constant from 40 to 100 mm Hg and showed a progressive increase from 100 to 180 mm Hg. These data suggest that the myogenic response of the adult rat testicular subcapsular artery may have an important role in the autoregulation of the testicular blood supply.

Pulmonary vasculature of piglets after correction of aorta-pulmonary shunts

In a previous article we described the functional and structural changes produced in the pulmonary arterial circulation of the growing pig by an aorta-pulmonary shunt. The present work describes the hemodynamic and morphologic adaptation that follows correction of the shunt. In four piglets, aged 5 weeks, an anastomosis was made between the thoracic descending aorta and the pulmonary trunk and left patent for 5 weeks. At the end of that time the mean pulmonary artery pressure (PAP) was 20 +/- 3.8 mm Hg (mean +/- SD), compared with 9 +/- 2.1 mm Hg in a group of four age-matched sham-operated control piglets. The shunt was then surgically closed. After 10 weeks' recovery, the PAP was similar and normal in the two groups. We have already shown that pulmonary hypertension of similar degree and duration to that at the end of the patent shunt period produces the following structural changes, assessed by quantitative techniques: (1) preacinar arteries of normal external diameter but with a thicker medial coat than normal and (2) intra-acinar arteries in normal concentration, of smaller external diameter than normal, but with a medial coat appropriate to the external diameter: Smooth muscle is found in more peripheral arteries than is normal. In the present study, at the end of the recovery period, the shunt animals were compared with the sham-operated animals and had thicker medial coats in preacinar and intra-acinar arteries, muscle in more peripheral arteries than is normal, and an increased arterial and alveolar concentration for unit lung area. These results indicate that, in the growing porcine lung, "recovery" from an aorta-pulmonary shunt that was associated with moderate pulmonary hypertension restores external arterial diameter to normal but leaves a thicker medial coat at the preacinar and intra-acinar levels and muscle more peripheral in the arterial bed. In addition, after shunt correction, multiplication of alveoli and arteries proceeds at a faster rate than normal, at least during the first 10 weeks of recovery.

Analysis for the non-invasive determination of arterial properties and for the transcutaneous continuous monitoring of arterial blood pressure

Analyses are developed for the procedures of (i) the noninvasive determination of the arterial elastic properties and (ii) the transcutaneous continuous monitoring of arterial blood pressure. Expressions for the pulse wave velocity and arterial pressure are derived, separately, in terms of (1) the nonlinear arterial elastic properties (the coefficients of the strain energy density function), the internal and external diameters of the deformed pressurised artery and the ratio of the unpressurised arterial internal and external diameters, and (2) the nonlinear arterial elastic properties, unpressurised tube diameters and the external diameter of the pressurised artery. It is then shown that if the values of the pulse velocities at an arterial section and of the corresponding arterial diameters are obtained (say, by transcutaneous ultrasonic monitoring) at three instants, then adequate equations are obtained (from the above pulse velocity expressions) which can be solved to yield the values of the arterial properties and the undeformed arterial internal and external diameters. These values are substituted in the expression for arterial pressure, to yield an expression for the arterial pressure, solely in terms of the external arterial diameters. Hence, by continuously transcutaneously ultrasonically monitoring the external arterial diameter, the arterial pressure can be monitored continuously and noninvasively. The feasibility and the required accuracy of making these measurements are currently under investigation.