The Process of Plaque Rupture: The Role of Vasa Vasorum and Medial Smooth Muscle Contraction Monitored by the Cardio-Ankle Vascular Index.

A warning sign for impending cardiovascular events is not fully established. In the process of plaque rupture, the formation of vulnerable plaque is important, and oxidized cholesterols play an important role in its progression. Furthermore, the significance of vasa vasorum penetrating the medial smooth muscle layer and being rich in atheromatous lesions should be noted. The cardio-ankle vascular index (CAVI) is a new arterial stiffness index of the arterial tree from the origin of the aorta to the ankle. The CAVI reflects functional stiffness, in addition to structural stiffness. The rapid rise in the CAVI means medial smooth muscle cell contraction and strangling vasa vasorum. A rapid rise in the CAVI in people after a big earthquake, following a high frequency of cardiovascular events has been reported. There are several cases that showed a rapid rise in the CAVI a few weeks or months before suffering cardiovascular events. To explain these sequences of events, we proposed a hypothesis: a rapid rise in the CAVI means medial smooth muscle contraction, strangling vasa vasorum, leading to ischemia and the necrosis of vulnerable plaque, and then the plaque ruptures. In individuals having a high CAVI, further rapid rise in the CAVI might be a warning sign for impending cardiovascular events. In such cases, treatments to decrease the CAVI better be taken soon.

A Case of Young Obese Heart Failure Patient Using Multidisciplinary Treatment Centered on the Fantastic Four Improved Cardio Ankle Vascular Index and Cardiac Function.

Obesity-induced heart failure (HF) in young people is a serious problem. The treatments for HF have developed in recent years. The following four basic HF drugs have been widely recognized as the "Fantastic Four": beta-adrenergic blocking agents, mineralocorticoid receptor antagonists (MRA), sodium glucose transporter 2 inhibitors (SGLT2 inhibitors), and angiotensin receptor neprilysin inhibitors (ARNI). However, the interaction between the heart and blood vessels has not received much attention. The cardio-ankle vascular index (CAVI) is an arterial stiffness index that is unaffected by blood pressure at the time of measurement. A 34-year-old obese man was admitted with dyspnea and edema. His cardiac function was severely impaired, and CAVI was increased. After administration of multidisciplinary HF treatment centered on the "Fantastic Four", his cardiac function and CAVI improved dramatically in a short time period. This case suggests the importance of improvement both cardiac and vascular function for the treatment of HF.

Changes in blood pressure and arterial stiffness monitored using the cardio-ankle vascular index during hemodialysis.

During hemodialysis (HD), blood pressure (BP) changes are frequently observed. However, the mechanism of BP changes during HD has not been fully clarified. The cardio-ankle vascular index (CAVI) reflects the arterial stiffness of the arterial tree from the origin of the aorta to the ankle independent from BP during measurement. Additionally, CAVI reflects functional stiffness in addition to structural stiffness. We aimed to clarify the role of CAVI in regulating the BP system during HD. We included 10 patients undergoing 4-hour HD (total 57 HD sessions). Changes in the CAVI and various hemodynamic parameters were evaluated during each session. During HD, BP decreased and CAVI significantly increased (CAVI, median [interquartile range]; 9.1 [8.4-9.8] [0 min] to 9.6 [9.2-10.2] [240 min], p < 0.05). Changes in CAVI from 0 min to 240 min were significantly correlated with water removal rate (WRR) (r = -0.42, p = 0.002). Changes in CAVI at each measurement point were negatively correlated with ΔBP (Δsystolic BPeach MP, r = -0.23, p < 0.0001; Δdiastolic BPeach MP, r = -0.12, p = 0.029). Whereas one patient exhibited a simultaneous decrease in BP and CAVI during the initial 60 min of HD. Arterial stiffness monitored with CAVI generally increased during HD. CAVI elevation is associated with decreased WWR and BP. An increase in CAVI during HD may reflect the contraction of smooth muscle cells and play an important role in BP maintenance. Hence, measuring CAVI during HD may distinguish the cause of BP changes.

The role of arterial stiffness in the onset of Takotsubo cardiomyopathy observed with noradrenaline administration and intracranial blood injection in rabbits.

Takotsubo cardiomyopathy (TCM) has been reported to occur after subarachnoid hemorrhage, and the involvement of a critical activity of catecholamines has been mentioned, but the details of its onset have not been fully clarified. Recently, proper arterial stiffness could be measured with cardio-ankle vascular index. Therefore, we aimed to clarify the role of arterial stiffness in onset of TCM using rabbits under infusion of noradrenaline and injection of blood into brain ventricle. Rabbits were divided into three groups: infusion of noradrenaline (group A), infusion of noradrenaline + injection of saline into the brain ventricle (group B), infusion of noradrenaline + injection of blood in the brain ventricle (group C). Aortic arterial stiffness beta (Aß) and femoral arterial stiffness beta (Fß) were defined according to definition of the cardio-ankle vascular index. Blood pressure (BP), Aß, Fß, and femoral vessel resistance (FVR) were measured. Left ventricular movement were monitored with echocardiography. BP increased uniformly in all three groups. Fß in the group A, B and C increased from 3.6 ± 3.2, 3.6 ± 3.6 and 3.9_ ± 4.2 to 15 ± 2, 17.9 ± 2.4, 34.8 ± 9.1 due to the ICP enhancements in addition to noradrenaline administration, respectively. Fß in groups B and C was significantly larger than that in group A. On echocardiography, a much higher akinesic area of the apex was observed in group C compared with group A and B. Cardiac movements similar to TCM were observed slightly in group B and definitely in group C. Noradrenaline administration infusion and blood injection into the brain ventricle induced TCM accompanying with enhanced femoral arterial stiffness. These results suggested that elevated arterial stiffness might be involved in the formation of TCM in addition to a critical activity of catecholamines and an increase in intracranial pressure with blood injection.

Rapid Rise in Cardio-Ankle Vascular Index as a Predictor of Impending Cardiovascular Events -Smooth Muscle Cell Contraction Hypothesis for Plaque Rupture.

Predictive factors for vascular events have not been established. The vasculature of the atheroma is supplied by penetration of the vasa vasorum through the smooth muscle cell layer from the adventitia. Smooth muscle cell contraction induces compression of the vasa vasorum, resulting in ischemia in intimal atheromatous lesions. Cardio-ankle vascular index (CAVI) has become known as an index of arterial stiffness of the arterial tree from the origin of the aorta to the ankle. CAVI reflects the progress of arteriosclerosis, and a rapid rise in CAVI indicates arterial smooth muscle cell contraction. We hypothesized that rapidly increased arterial stiffness evaluated by CAVI may be a predictor of impending cardiovascular events.

Analysis of effects of acute hypovolemia on arterial stiffness in rabbits monitored with cardio-ankle vascular index.

Although elasticity of the conduit arteries is known to be contribute effective peripheral circulation via Windkessel effects, the relationship between changes in intra-aortic blood volume and conduit artery elasticity remains unknown. Here we assessed the effects of change in intra-aortic blood volume induced by blood removal and subsequent blood transfusion on arterial stiffness and the involvement of autonomic nervous activity using our established rabbit model in the presence or absence of the ganglion blocker hexamethonium (100 mg/kg). Blood removal at a rate of 1 mL/min gradually decreased the blood pressure and blood flow of the common carotid artery but increased a stiffness indicator the cardio-ankle vascular index, which was equally observed in the presence of hexamethonium. These results suggest that arterial stiffness acutely responds to changes in intra-aortic blood volume independent of autonomic nervous system modification.

Recurrent Takotsubo syndrome complicated with ischemic enteritis successfully treated by hydration: a case report.

BACKGROUND: Takotsubo syndrome is a sudden and an acute form of transient cardiac dysfunction, triggered by mental and physical stress. The treatment for Takotsubo syndrome is not well understood and is incompletely established. Takotsubo syndrome is partly thought to be caused by coronary ischemia under sympathetic nerve activation. CASE PRESENTATION: We report the case of an 80-year-old Japanese woman with recurrent Takotsubo syndrome complicated with ischemic enteritis. In this case, abdominal pain and dehydration due to ischemic enteritis is thought to have triggered Takotsubo syndrome. Her life was saved with rapid, adequate intravenous hydration. She was diagnosed with coronary vasospastic angina using coronary angiography on her second admission. This case highlights the potential of adequate intravenous hydration in increasing coronary blood flow. In our case, it should be noted that pulmonary congestion was mild and may have improved Takotsubo syndrome without the use of diuretics. CONCLUSION: Adequate hydration must be considered for prompt improvement of cardiac function in Takotsubo syndrome. Replenishment of fluid to increase coronary blood flow, improvement of heart load without exacerbating heart failure, and stabilization of circulation dynamics can help treat patients with Takotsubo syndrome without using diuretics.

Predictive Value of the Cardio-Ankle Vascular Index for Cardiovascular Events in Patients at Cardiovascular Risk.

Background Arterial stiffness is an important predictor of cardiovascular events; however, indexes for measuring arterial stiffness have not been widely incorporated into routine clinical practice. This study aimed to determine whether the cardio-ankle vascular index (CAVI), based on the blood pressure-independent stiffness parameter ß and reflecting arterial stiffness from the origin of the ascending aorta, is a good predictor of cardiovascular events in patients with cardiovascular disease risk factors in a large prospective cohort. Methods and Results This multicenter prospective cohort study, commencing in May 2013, with a 5-year follow-up period, included patients (aged 40‒74 years) with cardiovascular disease risks. The primary outcome was the composite of cardiovascular death, nonfatal stroke, or nonfatal myocardial infarction. Among 2932 included patients, 2001 (68.3%) were men; the mean (SD) age at diagnosis was 63 (8) years. During the median follow-up of 4.9 years, 82 participants experienced primary outcomes. The CAVI predicted the primary outcome (hazard ratio, 1.38; 95% CI, 1.16‒1.65; P<0.001). In terms of event subtypes, the CAVI was associated with cardiovascular death and stroke but not with myocardial infarction. When the CAVI was incorporated into a model with known cardiovascular disease risks for predicting cardiovascular events, the global χ2 value increased from 33.8 to 45.2 (P<0.001), and the net reclassification index was 0.254 (P=0.024). Conclusions This large cohort study demonstrated that the CAVI predicted cardiovascular events. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT01859897.

Increased Arterial Stiffness in Chronic Thromboembolic Pulmonary Hypertension Was Improved with Riociguat and Balloon Pulmonary Angioplasty: A Case Report.

BACKGROUND: The role of arterial stiffness in the pathophysiology of chronic thromboembolic pulmonary hypertension (CTEPH) is unclear. The cardio-ankle vascular index (CAVI) is a novel arterial stiffness index reflecting stiffness of the arterial tree from the origin of the aorta to the ankle, independent from blood pressure at the time of measurement. CAVI reflects functional stiffness, due to smooth muscle cell contraction or relaxation, and organic stiffness, due to atherosclerosis. Here, we report the case of a patient with an increased CAVI due to CTEPH and the improvement after riociguat administration and balloon pulmonary angioplasty (BPA). CASE PRESENTATION: A 65-year-old man suffered from dyspnea on exertion, and he was diagnosed with distal CTEPH. The mean pulmonary artery pressure (mPAP) was 51 mmHg, and the initial CAVI was 10.0, which is high for patient's age. In addition to right ventricular dysfunction, left ventricular dysfunction was observed as reduced global longitudinal strain (GLS-LV). After riociguat administration, CAVI decreased to 9.1 and GLS-LV improved from -10.3% to -17.3%, although pulmonary hypertension remained (mPAP 41 mmHg). Subsequently, a total of five BPA sessions were performed. Six months after the final BPA, mPAP decreased to 19 mmHg and GLS-LV improved to 19.3%. The patient was symptom free and his 6-minute walk distance improved from 322 m to 510 m. CAVI markedly decreased to 5.8, which is extremely low for his age. CONCLUSION: These observations suggested that arterial stiffness as measured by CAVI was increased in CTEPH, potentially deteriorating cardiac function because of enhanced afterload. The mechanism of the increase of CAVI in this case of CTEPH was obscure; however, riociguat administration and BPA might improve the pathophysiology of CTEPH partly by decreasing CAVI.

Rapid Rise of Cardio-Ankle Vascular Index May Be a Trigger of Cerebro-Cardiovascular Events: Proposal of Smooth Muscle Cell Contraction Theory for Plaque Rupture.

Cardiovascular diseases have been recognized as the main cause of death all over the world. Recently, the established cardio-ankle vascular index (CAVI) has become known as an index of arterial stiffness of the arterial tree from the origin of the aorta to the ankle. CAVI reflects the progress of arteriosclerosis, and a rapid rise in CAVI indicates arterial smooth muscle cell contraction. Considering the vasculature of the atheroma where vasa vasorum penetrates the smooth muscle cell layer and supplies blood to the intimal atheromatous lesion, a rapid rise of CAVI means "choked" atheroma. Thus, we proposed a "smooth muscle cell contraction" hypothesis of plaque rupture.

Effects of Enhanced Intracranial Pressure on Blood Pressure and the Cardio-Ankle Vascular Index in Rabbits.

AIM: Stroke is well known to lead to hypertension; nevertheless, the role of vascular function in hypertension remains unclear. In this study, we aimed to clarify the mechanism underlying increased arterial stiffness following stroke. METHODS: The cardio-ankle vascular index (CAVI) was measured in five New Zealand White rabbits. Under general anesthesia, intracranial pressure (ICP) was increased by injecting saline (15 mL) into the cisterna magna. ICP was monitored using a catheter inserted into the subarachnoid space via right frontal bone craniotomy. Blood pressure (BP), CAVI, and common carotid flow (CCF) were evaluated, and the responses of these parameters to increased ICP were analyzed. RESULTS: Saline injection into the cisterna magna increased the ICP by over 20 mmHg. Both BP and CAVI increased from 63.2±4.84 to 128.8±14.68 mmHg and from 4.02±0.28 to 4.9±0.53, respectively. Similarly, BP and CCF increased. When hexamethonium was administered before the increase in ICP, the increase in BP (132.2±9.41 mmHg with 10 mg/kg hexamethonium vs. 105.6±11.01 mmHg with 100 mg/kg hexamethonium) and CAVI (5.02±0.64 with 10 mg/kg hexamethonium vs. 4.82±0.42 with 100 mg/kg hexamethonium) were suppressed in a dose-dependent manner. CONCLUSION: Increased ICP causes an increase in BP and CAVI, suggesting that enhanced stiffness of the muscular arteries contributes to high BP. Blocking the autonomic nervous system with hexamethonium suppresses the increase in BP and CAVI, indicating that these increases are mediated by activation of the autonomic nervous system.

CAVI-Lowering Effect of Pitavastatin May Be Involved in the Prevention of Cardiovascular Disease: Subgroup Analysis of the TOHO-LIP.

AIM: In the TOHO Lipid Intervention Trial Using Pitavastatin (TOHO-LIP), a multicenter randomized controlled trial, pitavastatin significantly reduced cardiovascular (CV) events compared to atorvastatin in patients with hypercholesterolemia. To investigate the mechanism by which pitavastatin preferentially prevents CV events, we investigated the relationship between CV events and cardio-ankle vascular index (CAVI) using the TOHO-LIP database. METHODS: For the subgroup analysis, we selected patients from a single center, Toho University Sakura Medical Center. After excluding those who had CV events at baseline or during the first year, 254 patients were enrolled. The primary end point was the same as that of TOHO-LIP, and three-point major cardiac adverse events (3P-MACE) was added as secondary end point. RESULTS: The cumulative 5-year incidence of 3P-MACE (pitavastatin 1.6%, atorvastatin 6.1%, P=0.038) was significantly lower in pitavastatin group (2 mg/day) than in atorvastatin group (10 mg/day). CAVI significantly decreased only in pitavastatin group during the first year (9.50-9.34, P=0.042), while the change in low-density lipoprotein cholesterol (LDL-C) did not differ between the two groups. The change in CAVI during the first year positively correlated with 3P-MACE and tended to be an independent predictor of 3P-MACE in Cox proportional hazards model (hazard ratio, 1.736; P=0.079). The annual change in CAVI throughout the observation period was significantly higher in subjects with CV events compared to those without. CONCLUSIONS: In this subgroup analysis, the reduction in CV events tended to be associated with the CAVI-lowering effect of pitavastatin, which was independent of the LDL-C-lowering effect.

Effect of nicorandil administration on cardiac burden and cardio-ankle vascular index after coronary intervention.

Myocardial injury is a problem associated with percutaneous coronary intervention (PCI). This study aimed to clarify the role of nicorandil administration in preventing myocardial injury. This study included patients with stable angina who underwent PCI from November 2013 to June 2016. Of 58 consecutive patients, the first 20 patients received only saline infusion after PCI (control group); the other 38 patients received a continuous intravenous infusion of nicorandil and saline after PCI (nicorandil group). Troponin I and brain natriuretic peptide (BNP) levels were measured. Vascular parameters, such as blood pressure (BP), cardiac output, cardio-ankle vascular index (CAVI), and estimated systemic vascular resistance (eSVR), were measured. Troponin I of both groups increased 12 h after PCI. Changes in BNP levels between immediately after PCI and 12 h after PCI were significantly higher in the control than in the nicorandil group (10.8 ± 44.2 vs. - 2.6 ± 14.6 pg/ml, p = 0.04). In the nicorandil group, BP, eSVR, and CAVI decreased significantly at 12 h after PCI compared with those immediately after PCI (p < 0.0001), whereas no change was observed in the control group. In a single linear analysis, the change in BP (r = 0.36, p < 0.01) and nicorandil administration (r = - 0.47, p < 0.001) was significantly correlated with the change in CAVI, multiple regression analysis revealed that the changes in CO and eSVR were significant contributing factors for the changes in CAVI. PCI could result in myocardial injury and/or cardiac burden in patients with stable angina. Nicorandil administration after PCI may be effective in relieving the burden by decreasing arterial stiffness (CAVI).

Factors affecting superficial vein visibility at the upper limb in healthy young adults: A cross-sectional observational study.

OBJECTIVE: Venipuncture is an invasive procedure, and repeated puncture attempts may be uncomfortable or even traumatic for patients. Vein visibility is one of the most influential variables for the failure of venipuncture; however, the factors affecting vein visibility remain unclear. The present study was conducted to identify the factors influencing vein visibility at the upper limb in healthy young adults. METHODS: Twenty-seven healthy volunteers were included. All measurements were performed at the right arm, right cubital fossa, and right forearm. The depth and cross-sectional area of superficial veins were measured by ultrasonography. Skin color was assessed by a spectrophotometer and quantified according to Commission International d'Eclairage L*a*b* values. RESULTS: Invisible superficial veins were significantly deeper and had a larger cross-sectional area than visible superficial veins. Skin color b* of invisible superficial veins was significantly higher than that of visible superficial veins. Vein depth, skin color b*, and gender markedly affected superficial vein visibility at the upper limb. The cutoff for vein depth was 2.3 mm (area under the curve = 0.91). CONCLUSION: The present results confirmed that vein depth, skin color b*, and gender strongly influenced vein visibility at the upper limb. The cutoff for vein depth was 2.3 mm.

Outcome of pitavastatin versus atorvastatin therapy in patients with hypercholesterolemia at high risk for atherosclerotic cardiovascular disease.

BACKGROUND: There has been no report about outcome of pitavastatin versus atorvastatin therapy in high-risk patients with hypercholesterolemia. METHODS: Hypercholesterolemic patients with one or more risk factors for atherosclerotic diseases (n = 664, age = 65, male = 54%, diabetes = 76%, primary prevention = 74%) were randomized to receive pitavastatin 2 mg/day (n = 332) or atorvastatin 10 mg/day (n = 332). Follow-up period was 240 weeks. The primary end point was a composite of cardiovascular death, sudden death of unknown origin, nonfatal myocardial infarction, nonfatal stroke, transient ischemic attack, or heart failure requiring hospitalization. The secondary end point was a composite of the primary end point plus clinically indicated coronary revascularization for stable angina. RESULTS: The mean low-density lipoprotein cholesterol (LDL-C) level at baseline was 149 mg/dL. The mean LDL-C levels at 1 year were 95 mg/dL in the pitavastatin group and 94 mg/dL in the atorvastatin group. There were no differences in LDL-C levels between both groups, however, pitavastatin significantly reduced the risk of the primary end point, compared to atorvastatin (pitavastatin = 2.9% and atorvastatin = 8.1%, HR, 0.366; 95% CI 0.170-0.787; P = 0.01 by multivariate Cox regression) as well as the risk of the secondary end point (pitavastatin = 4.5% and atorvastatin = 12.9%, HR = 0.350; 95%CI = 0.189-0.645, P = 0.001). The results for the primary and secondary end points were consistent across several prespecified subgroups. There were no differences in incidence of adverse events between the statins. CONCLUSION: Pitavastatin therapy compared with atorvastatin more may prevent cardiovascular events in hypercholesterolemic patients with one or more risk factors for atherosclerotic diseases despite similar effects on LDL-C levels.

Anatomically safe sites for intramuscular injections: a cross-sectional study on young adults and cadavers with a focus on the thigh.

The anatomical safety of intramuscular injections at the deltoid and ventrogluteal sites has been investigated; however, the anatomical relationship between intramuscular injection sites in the thigh and major blood vessels and nerves remains unclear. We aimed to compare intramuscular injection sites in the rectus femoris and vastus lateralis with those at the deltoid and ventrogluteal sites and identify safe intramuscular injection sites in the thigh. Twenty-seven young adult volunteers were recruited, and the thicknesses of subcutaneous tissue and muscle as well as the number of blood vessels present were evaluated at two sites on the deltoid, ventrogluteal, and thigh using ultrasound equipment. The right thighs of 24 cadavers were used, and the thickness of muscle, number of blood vessels or nerves present, and the distance between each examined site and major blood vessels or nerves were evaluated in the rectus femoris and vastus lateralis. A major blood vessel was observed in the middle of the rectus femoris in young adults. In cadavers, the descending branch of the lateral circumflex femoral artery and muscle branch of the femoral nerves to the vastus lateralis were observed at the middle point, distal two-thirds point, and middle point between the middle and distal two-thirds points of the rectus femoris, but not at the middle of the vastus lateralis. The middle of the vastus lateralis is an appropriate site for intramuscular injections because of the low risk of vascular or nerve damage. The present results support good practices for site selection for intramuscular injections.

Gender differences in the influence of obstructive sleep apnea on optic nerve head circulation.

We investigated gender differences in the optic nerve head (ONH) microcirculation status in association with obstructive sleep apnea (OSA) by using laser speckle flowgraphy (LSFG). We evaluated 150 men (60.5 ± 11.0 yrs) and 45 women (63.0 ± 10.6 yrs) who underwent overnight polysomnography. The mean blur rate (MBR), maximum (Max) MBR, and minimum (Min) MBR were evaluated. The parameters were analyzed separately for the tissues, vessels, and throughout the ONH (All). The apnea hypopnea index (AHI: times/hr), the lowest SpO2%, and the mean SpO2% were calculated as indicators of OSA. We investigated which MBR sections are correlated with OSA parameters separately in the men and women. All MBR sections in the women were significantly positively correlated with the lowest SpO2. In the men, no MBR section was correlated with any OSA parameters. The factors contributing independently to MBR-Tissue were height (ß = 0.31) and lowest SpO2 (ß = 0.30). The lowest SpO2 in the women was significantly positively correlated with Max MBR-Tissue, Max MBR-All, and Min MBR-All. Our results confirmed a gender difference in characteristics of ONH microcirculation in association with OSA.

Sleep-Disordered Breathing Is a Stronger Risk Factor for Proliferative Diabetic Retinopathy than Metabolic Syndrome and the Number of Its Individual Components.

PURPOSE: To evaluate whether the features of sleep-disordered breathing (SDB) are stronger independent factors for proliferative diabetic retinopathy (PDR) compared to the incidence of metabolic syndrome (MetS) and the number of its individual components. METHODS: We studied a cross-sectional total of 132 patients with type 2 diabetes. Thirty-nine patients had non-proliferative diabetic retinopathy (NPDR) and 93 patients had PDR. Pulse oximetry was conducted, and the patients' mean oxygen saturation (mean SpO2%) and 4% oxygen desaturation index (4% ODI times/hour) were evaluated. We compared the SDB and MetS variables between the NPDR and PDR patients. A logistic regression analysis was used to determine the independent factors for the diagnosis of PDR. RESULTS: The MetS diagnosis was made significantly more often in the PDR group (p = 0.04). The number of individual MetS components was significantly greater in the PDR group compared to the NPDR group (p = 0.01). The mean SpO2 of the NPDR group was not significantly different from that of the PDR group. The 4% ODI in the NPDR group was significantly lower than that in the PDR group (p = 0.01). The logistic regression analysis using the prevalence of MetS and the number of MetS components revealed that younger age and high 4%ODI value were independent factors contributing to the diagnosis of PDR. CONCLUSION: Our findings confirmed that compared to MetS and the number of its individual components, SDB may be a factor contributing to the progression to PDR. However, further careful longitudinal validation studies are needed.

Physiological role of nitric oxide for regulation of arterial stiffness in anesthetized rabbits.

We assessed effects of acetylcholine and Nω-Nitro-l-arginine methyl ester hydrochloride (l-NAME) on the cardio-ankle vascular index (CAVI), an indicator of arterial stiffness from origin of aorta to tibial artery, in halothane-anesthetized rabbits. Acetylcholine decreased the blood pressure, femoral vascular resistance and CAVI, whereas l-NAME did not affect the CAVI at a hypertensive dose. The acetylcholine-induced decrement of CAVI was completely suppressed by l-NAME. These results suggest that the arterial stiffness in rabbits may be independent from homeostatic production of nitric oxide, however, it can be decreased by large amounts of nitric oxide that are intrinsically produced by exogenously administered acetylcholine.