Duration Of Hyperemia Research Articles

Clinical features of 26 cases of COVID-19-associated conjunctivitis.

To explore the clinical features of COVID-19-associated conjunctivitis with the objective of preventing the spread of infection. Retrospective cohort study. From March 2020 to March 2021, we retrospectively reviewed 26 (9.8%) consecutive COVID-19 patients with conjunctivitis among 282 COVID-19 cases admitted to our hospital. Clinical symptoms, onset date of conjunctivitis, time to patient recovery, and eye drop intervention were investigated. In addition, risk factors for developing conjunctivitis were statistically examined among 206 inpatients available for within 5 days of the onset. A multivariate analysis of conjunctivitis risk factors was performed. Among the 282 COVID-19 patients, 4 (1.4%) had conjunctival hyperemia as the primary symptom. The median time of onset was 4 days after the COVID-19 onset. Hyperemia was observed in all cases, but other ocular symptoms were rare.The median duration of hyperemia was 3 days. A multiple logistic regression analysis revealed that a young age (p=0.005) and current smoking habit (p=0.027) were independent risk factors for conjunctivitis after COVID-19. COVID-19-associated conjunctivitis is rare in the elderly and strongly associated with a history of smoking. It often occurs in the early stages of infection, and while hyperemia is recognized as a clinical symptom, other ocular symptoms are rare or non-existent. Many cases recover within a short time.

Impact of aging on the effects of intracoronary adenosine, peak hyperemia and its duration during fractional flow reserve assessment.

Functional assessment of coronary stenoses is crucial for determining the correct therapeutic strategy. Age-related modifications in cardiovascular function could alter the functional significance of an intermediate coronary lesion. Therefore, the aim of the present study was to investigate the impact of age on fractional flow reserve (FFR) measurements in patients with intermediate coronary artery disease. We included patients undergoing coronary angiography at our Division of Cardiology from June 2008 to February 2019 for elective indication or recent acute coronary syndrome and receiving FFR assessment for an intermediate coronary stenosis (angiographic 40-70% stenoses). FFR measurement was performed by pressure-recording guidewire (Prime Wire; Volcano Imaging System Philips Healthcare, San Diego, California, USA), after induction of hyperemia with intracoronary boluses of adenosine (from 60 to 720 μg, with dose doubling at each step). We included in our study 276 patients, undergoing FFR evaluation on 314 lesions, that were divided according to age (< or ≥70 years). Elderly patients displayed a higher cardiovascular risk profile and received more often specific therapy. We found significantly higher FFR values and lower Delta FFR and time to recovery in patients with age ≥70 years old even with high-dose adenosine. Elderly patients showed a trend in lower percentage of positive FFRs, especially with high-dose (P = 0.09). Overall, any FFR ≤ 0.80 was observed in 33.5% of younger patients and 21.1% of patients ≥70 years (P = 0.02). Results were confirmed after correction for baseline differences [adjusted odds ratio (95% confidence interval) = 0.60 (0.33-1.09), P = 0.08]. This is one of the first studies investigating the impact of age on the measurement of FFR with high-dose adenosine. Patients with age >70 years old with intermediate CAD are more likely to have higher FFR values and lower duration of hyperemia after adenosine boluses, as compared with younger patients.

Abstract 15437: Intravenous Nicorandil versus Adenosine for Fractional Flow Reserve Measurement to Assess Coronary Artery Stenosis: A Systematic Review and Meta-analysis

Background: Fractional flow reserve (FFR) has become an increasingly accepted modality to assess coronary artery stenosis. Several clinical trials have been conducted to compare the effects of various pharmacologic agents, including nicorandil and adenosine, in achieving maximum coronary hyperemia. Methods: We searched PubMed, Cochrane Library, Scopus, and Web of Sciencefor randomized and observational studies comparing nicorandil with adenosine for measurement of FFR. Data were extracted from the eligible studies and pooled in a meta-analysis using the Revman software. Dichotomous data were pooled as risk ratio (RR) and continuous data were pooled as standardized mean difference (SMD) with the corresponding 95% confidence intervals (CI).We aimed to evaluate the average FFR, hyperemia, duration of hyperemia, decrease in systolic blood pressure, and pain scores assessed by visual analog scale (VAS). Results: Five studies comprising a total of 595 patients met our inclusion criteria. The combined effect estimate favored nicorandil over adenosine for mean FFR (SMD = -0.17, 95% CI [-0.28, -0.06], P = 0.004). Nicorandil was more effective in achieving adequate hyperemia as compared to adenosine (SMD = -2.06, 95% CI [-4.36, -0.84], P=0.004). However, no significant differences were reported between nicorandil and adenosine in the duration of hyperemia, the decrease in systolic blood pressure, and VAS pain scores. Conclusion: Nicorandil is associated with superior clinical outcomes and similar safety profile as compared to adenosine and should therefore be considered as an alternative agent for FFR evaluation.

Relationship between adenosine A2a receptor polymorphism rs5751876 and fractional flow reserve during percutaneous coronary intervention.

Fractional flow reserve (FFR) assessed during adenosine-induced maximal hyperemia has emerged as a useful tool for the guidance of percutaneous coronary interventions (PCI). However, interindividual variability in the response to adenosine has been claimed as a major limitation to the use of adenosine for the measurement of FFR, carrying the risk of underestimating the severity of coronary stenoses, with potential negative prognostic consequences. Genetic variants of the adenosine receptor A2a (ADORA2A gene), located in the coronary circulation, have been involved in the modulation of the hyperemic response to adenosine. However, no study has so far evaluated the impact of the single nucleotide polymorphism rs5751876 of ADORA2A on the measurement of FFR in patients undergoing percutaneous coronary intervention that was, therefore, the aim of our study. We included patients undergoing coronary angiography and FFR assessment for intermediate (40-70%) coronary lesions. FFR measurement was performed by pressure-recording guidewire (Prime Wire, Volcano), after induction of hyperemia with intracoronary boli of adenosine (from 60 to 1440μg, with dose doubling at each step). Restriction fragment length polymorphism (RFLP) analysis was performed to assess the presence of rs5751876 C>T polymorphism of ADORA2a receptor. We included 204 patients undergoing FFR measurement of 231 coronary lesions. A total of 134 patientscarried the polymorphism (T allele), of whom 41 (30.6%) in homozygosis (T/T).Main clinical and angiographic features did not differ according to ADORA2A genotype. The rs5751876 C>T polymorphism did not affect mean FFR values (p = 0.91), the percentage of positive FFR (p = 0.54) and the duration of maximal hyperemia. However, the time to recovery to baseline FFR values was more prolonged among the T-allele carriers as compared to wild-type patients (p = 0.04). Based on these results, in patients with intermediate coronary stenoses undergoing FFR assessment with adenosine, the polymorphism rs5751876 of ADORA2A does not affect the peak hyperemic response to adenosine and the results of FFR. However, a more prolonged effect of adenosine was observed in T-carriers.

Post-occlusional hyperemia for fractional flow reserve assessment and pull-back curve analysis.

Balloon occlusion is a potential method for inducing hyperemia to measure post-percutaneous coronary intervention (PCI) fractional flow reserve (FFR). The objective of this study was to determine the clinical usefulness of post-occlusional hyperemia. FFRs measured using post-occlusional hyperemia caused by 30 (FFRoccl30) and 60s (FFRoccl60) of balloon occlusion after PCI were compared in 60 lesions from 60 patients. The duration of hyperemia was also measured. There was a strong correlation between FFRoccl30 and FFRoccl60 (r = 0.969, p < 0.01). The duration of hyperemia was significantly longer with FFRoccl60 than with FFRoccl30 (68 ± 23 vs. 37 ± 15s, p < 0.01). The time required for pullback curve analysis was around 45s. However, in 7 (12%) cases, the duration of hyperemia with FFRoccl60 was < 45s, which was not enough for pull-back curve analysis. To predict the duration of hyperemia with FFRoccl60 ≥ 45s, the receiver operating characteristic curve analysis revealed a cut-off value of 25s of hyperemia with FFRoccl30. FFRoccl30 is sufficient for diagnostic purposes. FFRoccl60 is suitable for pull-back curve analysis in select cases based on predictions made using the duration of hyperemia with FFRoccl30.

Impact of increasing dose of intracoronary adenosine on peak hyperemia duration during fractional flow reserve assessment

BackgroundFractional Flow Reserve (FFR) is currently indicated as a first line strategy for the functional assessment of intermediate coronary stenoses. However, the protocol for inducing hyperemia still lacks standardization. Intracoronary adenosine boli, with a progressive increase to high-dosage, have been proposed as a sensitive and accurate strategy for the classification of coronary stenoses, although being potentially affected by the achievement of plateau of the effect and by a less prolonged and stable hyperemia as compared to intravenous administration. Therefore, the aim of the present study was to define the conditioning parameters and assess the impact of increasing-dose intracoronary adenosine on peak hyperemia duration in patients undergoing FFR for intermediate coronary stenoses. MethodsFFR was assessed in patients with intermediate (40 to 70%) lesions by pressure-recording guidewire (Prime Wire, Volcano), after induction of hyperemia with intracoronary boli of adenosine (from 60 to 1440 μg, with dose doubling at each step). Hyperemic duration was defined as the time for the variation form minimum FFR ± 0.02 and time to recovery till baseline values. ResultsWe included 87 patients, undergoing FFR evaluation of 101 lesions. Mean peak hyperemia duration and time to recovery significantly increased with adenosine doses escalation (p = 0.02 and p < 0.001). Peak hyperemia duration and time to recovery with 1440 μg adenosine were 14.5 ± 12.6 s and 45.2 ± 30.7 s, respectively. Hyperemia duration was not related to Quantitative Coronary Angiography (QCA) parameters or FFR values. In fact, a similar increase in the time of hyperemic peak was noted when comparing patients with positive or negative FFR (pbetween = 0.87) or patients with lesions < or ≥20 mm (pbetween = 0.92) and lesions involving left main coronary or proximal left anterior descending artery (LAD) (pbetween = 0.07). A linear relationship was observed between time to recovery and FFR variations, with a greater time to baseline required in patients with FFR ≤ 0.80 (p = 0.003) and in lesions ≥ 20 mm (p = 0.006), but not in LAD/LM lesions (p = 0.55). ConclusionsThe present study shows a progressive raise in the duration of peak hyperemia and time to recovery, after the administration of increasing doses of intracoronary adenosine for the assessment of FFR. Therefore, considering the potential advantages of a high-dose adenosine protocol, allowing a more prolonged hyperemia and a more precise and reliable measurement of FFR, further larger studies with such FFR strategy should certainly be advocated to confirm its safety and benefits, before its routinely use recommendation.

Real time cerebral blood flow monitoring by laser speckle contrast imaging after cardiac arrest with targeted temperature management

Brain injury is the main cause of mortality and mobidity after cardiac arrest (CA). Changes in cerebral blood flow (CBF) after reperfusion are associated with brain injury and recovery. Target temperature management (TTM) is the most effective treatment of CA patient. Despite of the advancement in detecting techniques, a real time CBF monitoring technique after CA and TTM, with a wide field of view and high spatiotemperal resolution, has not been established yet. Fourteen rats underwent 7 min asphyxia-CA and were randomly treated with 6 h post-resuscitation normothermic (36.5–37.5 °C) or hypothermic (32–34 °C) targeted temperature management (TTM) ( n = 7). rCBF was monitored by a laser speckle contrast imaging (LSCI) technique. Brain recovery was evaluated by neurologic deficit score (NDS) and quantitative EEG - information quantity (qEEG-IQ). There were regional differences in rCBF among veins of distinct cerebral areas. The rostral vein had a higher rCBF at the hyperemia phase [3–12 min after return of spontaneous circulation (ROSC)] and a lower rCBF at the hypoperfusion phase (40–90 min after ROSC) compared with both the middle and caudal veins. There were heterogeneous responses among the three components of the vascular system. The rCBF of capillaries increased more than that of veins and arteries in the hyperemia phase but decreased more in the hypoperfusion phase. Hypothermia immediately following ROSC led to a longer hyperemia duration, a lower rCBF at the hypoperfusion phase, a better NDS and a higher qEEG-IQ compared with normothermic TTM. This is the first report on continuous CBF monitoring at the level of individualized vessels with high spatial and temporal resolutions in the setting of CA. The quantified rCBF response may help uncover the mechanism of injury and recovery after global brain ischemia and TTM.

Intravenous nicorandil versus adenosine for fractional flow reserve measurement: a crossover, randomized study.

Nicorandil has vasodilatory effects on both the epicardial coronary arteries and the coronary microvasculature, thereby increasing coronary blood flow. The objective of the present study was to investigate the effectiveness of intravenous (IV) nicorandil infusion for fractional flow reserve (FFR) measurement. In this crossover randomized study, 49 patients underwent FFR measurement with a consecutive randomized order of patient-blind infusions of continuous IV adenosine administration and a single bolus IV administration of nicorandil. The primary endpoint was the difference between the FFR by nicorandil and the FFR by adenosine, as assessed by the Bland-Altman method. The mean FFR value measured by nicorandil was not significantly different from that measured by adenosine [0.8125 ± 0.1349 vs. 0.7978 ± 0.124; mean difference, 0.0147 (95% confidence interval - 0.0373, 0.0667); P = 0.58]. There was no clinically significant diagnostic discordance, with the FFR by nicorandil > 0.80 and that by adenosine < 0.75. Hyperemia was achieved earlier using nicorandil than adenosine (34 ± 13 vs. 58 ± 15, P < 0.001). The duration of hyperemia after IV nicorandil was variable (6-570s, mean 89 ± 98s). IV nicorandil decreased systolic blood pressure by 32 ± 16mm Hg (24 ± 10%) from baseline. Linear regression analysis showed that the average FFR value and the difference in systolic blood pressure were significantly associated with the bias in the FFR value between the two drugs. In conclusions, the results of the present study suggest that IV nicorandil can achieve maximal hyperemia easily and rapidly, providing an acceptable diagnostic performance for FFR assessment. However, a wide range of variation in hyperemic plateau and adecrease in blood pressure are the major limitations of this method.

Real-time quantitative monitoring of cerebral blood flow by laser speckle contrast imaging after cardiac arrest with targeted temperature management

Brain injury is the main cause of mortality and morbidity after cardiac arrest (CA). Changes in cerebral blood flow (CBF) after reperfusion are associated with brain injury and recovery. To characterize the relative CBF (rCBF) after CA, 14 rats underwent 7 min asphyxia-CA and were randomly treated with 6 h post-resuscitation normothermic (36.5–37.5℃) or hypothermic- (32–34℃) targeted temperature management (TTM) (N = 7). rCBF was monitored by a laser speckle contrast imaging (LSCI) technique. Brain recovery was evaluated by neurologic deficit score (NDS) and quantitative EEG – information quantity (qEEG-IQ). There were regional differences in rCBF among veins of distinct cerebral areas and heterogeneous responses among the three components of the vascular system. Hypothermia immediately following return of spontaneous circulation led to a longer hyperemia duration (19.7 ± 1.8 vs. 12.7 ± 0.8 min, p < 0.01), a lower rCBF (0.73 ± 0.01 vs. 0.79 ± 0.01; p < 0.001) at the hypoperfusion phase, a better NDS (median [25th–75th], 74 [61–77] vs. 49 [40–77], p < 0.01), and a higher qEEG-IQ (0.94 ± 0.02 vs. 0.77 ± 0.02, p < 0.001) compared with normothermic TTM. High resolution LSCI technique demonstrated hypothermic TTM extends hyperemia duration, delays onset of hypoperfusion phase and lowered rCBF, which is associated with early restoration of electrophysiological recovery and improved functional outcome after CA.

Postocclusional Hyperemia for Fractional Flow Reserve After Percutaneous Coronary Intervention.

Postocclusional hyperemia caused by balloon occlusion is a potential alternative method of inducing hyperemia for measuring post-percutaneous coronary intervention fractional flow reserve (FFR). The aim of this study was to investigate postocclusional hyperemia as a method of inducing hyperemia. FFR measured by postocclusional hyperemia (FFRoccl) caused by balloon occlusion after percutaneous coronary intervention was compared with FFR measured by drug-induced hyperemia (FFR measured by intravenous ATP; and FFR measured by intracoronary papaverine injection [FFRpap]) in 98 lesions from 98 patients. The hyperemia duration was also measured for FFRoccl and FFRpap. The correlation coefficient between FFRoccl, FFR measured by intravenous ATP (r=0.973; P<0.01), and FFRpap (r=0.975; P<0.01) showed almost identical values to those obtained for the correlation coefficient between FFR measured by intravenous ATP and FFRpap (r=0.967; P<0.01). No clear difference was observed on Bland-Altman analysis. Hyperemia duration was significantly longer with FFRoccl than with FFRpap (70±22 versus 51±25 s; P<0.01). Strong correlations were found between FFRoccl and FFR measured by intravenous ATP and FFRoccl and FFRpap. Hyperemia caused by FFRoccl was significantly longer than that caused by FFRpap.

2D.07

Objective: Coronary flow reserve (CFR) is a predictor of coronary artery disease. Inhalation of high concentration of the anaesthetic isoflurane (ISO) represents a non-invasive method to induce coronary vasodilation in mice avoiding intravenous adenosine infusion. However, not consistent protocols, especially concerning the time courses of the anesthesia administration, are reported. Aim of this work was to study the correct time course of coronary artery vasodilation. Design and method: Non-invasive 40 MHz Doppler ultrasound (VEVO2100, VisualSonics) was used to measure left coronary flow velocity at baseline (B, ISO1%) and at hyperemia (H, ISO2.5%). For six adult male mice (strain C57BL6, 6 months), isoflurane concentration was maintained at 1% for a 6-min period and then increased to 2.5% for the further 30 minutes. PW-Doppler images were acquired every two minutes and Velocity Time Integral (VTI) values were calculated for each time point providing VTI-time curves. Two mathematical models (sigmoid and exponential) were used to fit the data and the model providing the best fitting was used to calculate the mean time needed to reach the 90% of the plateau value (TT90). The obtained TT90 value was used to identify the duration of the high-isoflurane inhalation phase and the experiment was then repeated in ten mice (same strain and age) using the new time duration. CFR measurements (calculated as VTI(H)/VTI(B)) obtained in these conditions (CFRnew) were compared with those measured using a hyperemia duration as found in literature (approximately 4 minutes) (CFR4 min). Results: The fitting with the sigmoid model provided a lower total Absolute-Sum-of-Squares value than the exponential model (211.6 mm2 vs 405.1 mm2). The sigmoid model provided a TT90 measurements equal to 17.4 ± 6.9 minutes. Accordingly, the time point for the maximal flow was then fixed to 20.5 minutes (14 minutes of ISO2.5% after 6 minutes of ISO1%). CFR4 min values (2.10 ± 0.57) amounted to the 78.1% of CFRnew (2.8 ± 0.87) and the Bland-Altman analysis provided a significant bias of 0.69. Conclusions: These data suggest that short hyperemia durations cause a CFR underestimation; moreover, these results might be useful for the optimization of a standardized protocol for the non-invasive CFR evaluation in mice.

Effects of age and smoking on endothelial function assessed by quantitative cardiovascular magnetic resonance in the peripheral and central vasculature.

BackgroundBoth age and smoking promote endothelial dysfunction and impair vascular reactivity. Here, we tested this hypothesis by quantifying new cardiovascular magnetic resonance (CMR)-based biomarkers in smokers and nonsmokers.MethodsStudy population: young non-smokers (YNS: N = 45, mean age = 30.2 ± 0.7 years), young smokers (YS: N = 39 mean age 32.1 ± 0.7 years), older non-smokers (ONS: N = 45, mean age = 57.8 ± 0.6 years), and older smokers (OS: N = 40, mean age = 56.3 ± 0.6 years), all without overt cardiovascular disease. Vascular reactivity was evaluated following cuff-induced hyperemia via time-resolved blood flow velocity and oxygenation (SvO2) in the femoral artery and vein, respectively. SvO2 dynamics yielded washout time (time to minimum SvO2), resaturation rate (upslope) and maximum change from baseline (overshoot). Arterial parameters included pulse ratio (PR), hyperemic index (HI) and duration of hyperemia (TFF). Pulse-wave velocity (PWV) was assessed in aortic arch, thoracoabdominal aorta and iliofemoral arteries. Ultrasound-based carotid intimal-medial thickness (IMT) and brachial flow-mediated dilation were measured for comparison.ResultsAge and smoking status were independent for all parameters. Smokers had reduced upslope (−28.4%, P < 0.001), increased washout time (+15.3%, P < 0.01), and reduced HI (−19.5%, P < 0.01). Among non-smokers, older subjects had lower upslope (−22.7%, P < 0.01) and overshoot (−29.4%, P < 0.01), elevated baseline pulse ratio (+14.9%, P < 0.01), central and peripheral PWV (all P < 0.05). Relative to YNS, YS had lower upslope (−23.6%, P < 0.01) and longer washout time (13.5%, P < 0.05). Relative to ONS, OS had lower upslope (−33.0%, P < 0.01). IMT was greater in ONS than in YNS (+45.6%, P < 0.001), and also in YS compared to YNS (+14.7%, P < 0.05).ConclusionsResults suggest CMR biomarkers of endothelial function to be sensitive to age and smoking independent of each other.

A fish-based diet intervention improves endothelial function in postmenopausal women with type 2 diabetes mellitus: A randomized crossover trial

ObjectiveThe beneficial effects of fish and n-3 polyunsaturated fatty acids (PUFAs) consumption on atherosclerosis have been reported in numerous epidemiological studies. However, to the best of our knowledge, the effects of a fish-based diet intervention on endothelial function have not been investigated. Therefore, we studied these effects in postmenopausal women with type 2 diabetes mellitus (T2DM). Materials/MethodsTwenty-three postmenopausal women with T2DM were assigned to two four-week periods of either a fish-based diet (n-3 PUFAs≧3.0g/day) or a control diet in a randomized crossover design. Endothelial function was measured with reactive hyperemia using strain-gauge plethysmography and compared with the serum levels of fatty acids and their metabolites. Endothelial function was determined with peak forearm blood flow (Peak), duration of reactive hyperemia (Duration) and flow debt repayment (FDR). ResultsA fish-based dietary intervention improved Peak by 63.7%, Duration by 27.9% and FDR by 70.7%, compared to the control diet. Serum n-3 PUFA levels increased after the fish-based diet period and decreased after the control diet, compared with the baseline (1.49 vs. 0.97 vs. 1.19mmol/l, p<0.0001). There was no correlation between serum n-3 PUFA levels and endothelial function. An increased ratio of epoxyeicosatrienoic acid/dihydroxyeicosatrienoic acid was observed after a fish-based diet intervention, possibly due to the inhibition of the activity of soluble epoxide hydrolase. ConclusionsA fish-based dietary intervention improves endothelial function in postmenopausal women with T2DM. Dissociation between the serum n-3 PUFA concentration and endothelial function suggests that the other factors may contribute to this phenomenon.

Perfusion measurements of the calf in patients with peripheral arterial occlusive disease before and after percutaneous transluminal angioplasty using Mr arterial spin labeling

To evaluate muscle perfusion in patients with peripheral arterial occlusive disease (PAOD) before and after percutaneous transluminal angioplasty (PTA) of the limb by means of MR arterial spin labeling (ASL) perfusion measurements during reactive hyperemia. Ten patients with symptomatic PAOD affecting the iliac or femoral vessels were investigated before and after PTA. A pseudo-continuous arterial spin labeling (PCASL) MR technique was applied. Perfusion was measured in soleus and tibialis anterior muscle during reactive hyperemia. Key parameters such as mean perfusion value (Phyp ), time-to-peak (TTP) and duration of hyperemia (Thyp ) describing the perfusion signal curve were examined. Between baseline and post-PTA, Phyp increased in both muscle groups. At the same time, TTP and Thyp decreased in both muscle groups. At the same time the clinically assessed ankle brachial index (ABI) increased from 0.56 ± 0.10 to 0.83 ± 0.15. The impaired pain-free walking distance improved in all patients. PCASL MRI can detect changes of the key perfusion parameters Phyp , TTP, and Thyp after successful PTA of the calf muscles during reactive hyperemia and seems to be a promising tool for monitoring of interventional treatments.

Cerebral Hyperemia Measured with Near Infrared Spectroscopy during Treatment of Diabetic Ketoacidosis in Children

To use near infrared spectroscopy (NIRS) to evaluate the timing of onset and duration of cerebral hyperemia during diabetic ketoacidosis (DKA) treatment in children, and to investigate the relationship of cerebral hyperemia to intravenous fluid treatment. We randomized children aged 8-18 years with DKA to either more rapid or slower intravenous fluid treatment (19 total DKA episodes). NIRS was used to measure rSo2 during DKA treatment. NIRS monitoring began as soon as informed consent was obtained and continued until the patient was transferred out of the critical care unit. rSo2 values above the normal range (>80%) were detected in 17 of 19 DKA episodes (mean rSo2 during initial 8 hours of DKA treatment: 86% ± 7%, range 65%-95%). Elevated rSo2 values were detected as early as the second hour of DKA treatment and persisted for as long as 27 hours. Hourly mean rSo2 levels during treatment did not differ significantly by fluid treatment group. During DKA treatment, children have elevated rSo2 values consistent with cerebral hyperemia. Hyperemia occurs as early as the second hour of DKA treatment and may persist for ≥ 27 hours. Cerebral rSo2 levels during treatment did not differ significantly in patients treated with slower versus more rapid intravenous rehydration.

Spironolactone improves endothelial and cardiac autonomic function in non heart failure hemodialysis patients

Hemodialysis patients have a cardiovascular mortality rate of 20-40 times that of the general population. Aldosterone inhibition by spironolactone has exerted beneficial, prognostically significant cardiovascular effects in patients with heart failure maintained on hemodialysis or peritoneal dialysis. Our aim was to investigate spironolactone's effect in non heart failure hemodialysis patients. Fourteen stable chronic hemodialysis patients (nine men), 59.5 ± 3.1 years of age were evaluated in a sequential, fixed-dose, placebo-controlled study. Heart failure was diagnosed on the basis of signs and symptoms of heart failure or left ventricular ejection fraction less than 50%. Following an initial 4-month period of placebo administration after each dialysis, patients received spironolactone (25 mg thrice weekly after dialysis) for the next 4 months. Data were recorded at baseline, at the end of placebo administration, and at the end of spironolactone treatment and included endothelial function by forearm reactive hyperemia during venous occlusion plethysmography, cardiac autonomic status by heart rate variability in the time and frequency domain, blood pressure response, and echocardiographic and laboratory data. Placebo induced no changes in the aforementioned parameters. Following spironolactone, salutary effects were observed in the extent and duration of reactive hyperemia (P < 0.05 for both), as well as in heart rate variability (P < 0.05) and blood pressure control (P < 0.05). No changes occurred in echocardiographically derived left ventricular dimensions or mass. Low-dose spironolactone therapy in clinically stable non heart failure hemodialysis patients is associated with favorable effects on cardiovascular parameters known to adversely affect survival, such as endothelial dysfunction and heart rate variability. Spironolactone treatment might benefit long-term cardiovascular outcome of such patients.

Effects of Polymorphisms of NOS3 and GNB3 Genes on Skin Microvascular Reactivity in Normal Pregnancy

We studied the relationship between endothelial NO-synthase gene (NOS3) and G protein β3 subunit gene (GNB3) polymorphisms and reactivity of skin microvessels during physiological gestation. T-786C NOS3 polymorphism influenced the maximum blood flow rate in skin microvessels and the severity of postocclusive reactive hyperemia during the third trimester of pregnancy. The relationship between G894T NOS3 polymorphism and the duration of postocclusive reactive hyperemia was revealed. C825T GNB3 polymorphism affects the duration and severity of postocclusive reactive hyperemia during the first and third trimesters of pregnancy. Thus, NOS3 and GNB3 polymorphisms affect blood flow in the skin microvessels during physiological gestation.

Single Administration of &amp;alpha;-Glucosidase Inhibitors on Endothelial Function and Incretin Secretion in Diabetic Patients With Coronary Artery Disease

Post-prandial hyperglycemia, hyperlipidemia, and endothelial dysfunction play an important role in the pathogenesis of atherosclerosis. Improvement in post-prandial hyperglycemia on alpha-glucosidase inhibitors (alpha-GIs) is associated with a risk reduction of cardiovascular diseases, but the post-prandial effects of alpha-GIs on endothelial function and incretin secretion in type 2 diabetic patients with coronary artery disease (CAD) remain unclear. The post-prandial effects of a single administration of miglitol and voglibose on endothelial function and changing levels of glucose, insulin, lipids, glucagon-like peptide (GLP)-1, and gastric inhibitory polypeptide (GIP) were compared after a standard meal loading in 11 diabetic patients with CAD, using a placebo-controlled cross-over design. The changing levels of glucose, insulin and triglycerides at 60 min were significantly lower in the miglitol group than in the voglibose and placebo groups (all P<0.01). GLP-1 levels were significantly higher at 120 min (P<0.05) and GIP levels were significantly lower at 30 min and 60 min (P<0.05) in the miglitol group compared to other treatments. The reactive hyperemia duration at 120 min was significantly maintained in the miglitol group compared to the other groups. A single administration of miglitol significantly improved post-prandial glucose/lipid metabolism, incretin secretion, and endothelial dysfunction in diabetic patients with CAD, suggesting that miglitol may be a useful anti-atherogenic agent (UMIN000002264).

Characterization of tissue oxygen saturation and the vascular occlusion test: influence of measurement sites, probe sizes and deflation thresholds

IntroductionTissue oxygen saturation (StO2) and the vascular occlusion test (VOT) can identify tissue hypoperfusion in trauma and sepsis. However, the technique is neither standardized nor uses the same monitoring site. We hypothesized that baseline and VOT StO2 would be different in the forearm (F) and thenar eminence (TH) and that different minimal StO2 values during the VOT would result in different reoxygenation rates (ReO2).MethodsStO2 and its change during the VOT were simultaneously measured in the F and TH, with 15 mm and 25 mm probes, using the 325 InSpectra monitor in 18 healthy, adult volunteers. Two VOTs were done to a threshold thenar StO2 of 40% interchanging the 15 mm and 25 mm probes between sites. Two additional VOTs were done to thresholds of 50% and 30%. Baseline StO2 (BaseO2), the deoxygenation rate (DeO2) and ReO2 were compared between sites, probes and (%O2/minute) thresholds. Results are presented as the median (interquartile range), P-value.ResultsBaseO2, DeO2, ReO2, area under the curve and hyperemia duration values were different when comparing TH vs. F and 15 mm vs. 25 mm probes. ReO2 was different between different thresholds for the TH and 15 mm probes. TH15 mm vs. F15 mm: BaseO2, 90.4 (85.2, 93.5) vs. 85.2 (80.7, 90.2), P = 0.031; DO2, -12.1 (-16.2, -11.3) vs. -8.5 (-10.3, -7.8), P = 0.011; ReO2, 297.2 (213.7, 328.6), P < 0.0001; 15 mm vs. 25 mm probe: BaseO2, 97.2 (89.4, 94.7) vs. 87.3 (81.7, 90.9), P = 0.016; DeO2, -18.0 (-24.1, -14.8) vs. -9.9 (-15.3, -6.5), P < 0.0001; and ReO2, 401.6 (331.7, 543.2) vs. 160.5 (132.3, 366.9), P = 0.012, respectively. TH15 mm vs. TH25 mm: BaseO2, P = 0.020; DeO2, P < 0.0001; and ReO2, P < 0.0001. Threshold StO2 values (15 mm probe only): ReO2, P = 0.003; DeO2, P = 0.60. ReO2 at 40% and 50% StO2 thresholds, P = 0.01.ConclusionsBaseO2, DeO2 and ReO2 were different when measured in different anatomical sites (F and TH) and with different probe sizes, and ReO2 was different with differing VOT release StO2 threshold values. Thus, standardization of the site, probe and VOT challenge need to be stipulated when reporting data.

Vasodilation in Vasovagal Syncope and the Effect of Water Ingestion

Abnormal (increased, but also decreased) vasodilative responses have been observed in patients with vasovagal syncope (VVS). The objective was to assess reactive vasodilation in supine patients with VVS and its relation to severity of the syndrome. Reactive vasodilation was also assessed after a simple therapeutic intervention (water drinking). Thirty-four patients were studied, all with recurrent VVS and a recent positive head-up tilt test result. Seventeen matched healthy subjects served as controls. Venous occlusion plethysmography was used to assess forearm blood flow (FBF) and forearm vascular resistance resistance (1) at rest and (2) during reactive hyperemia. Clinical severity of the syndrome was related to the intensity and duration of the vasodilative reflex. The same plethysmographic measurements were repeated 60 minutes after drinking 500 ml of water. Before water drinking, no difference was observed between groups in baseline measurements. However, duration of hyperemia was longer in patients (p <0.05) and was related to the duration of the previous positive tilt test (r = -0.69, p <0.05) and total number of each patient's symptomatic vasovagal episodes (r = 0.49, p <0.05). After water ingestion, baseline FBF decreased in patients (p <0.05) and remained stable in controls. In patients, duration of hyperemia decreased to normal values. Hyperemic FBF remained similar between groups. In conclusion, increased reactive vasodilative reflexes were observed in patients with VVS. They seemed to be of significant pathophysiologic significance. Water drinking can normalize them for >or=60 minutes.