Nitroglycerin Infusion Research Articles

Comparative effects of propofol and nitroglycerine on efficacy of rewarming in patients undergoing on-pump coronary artery bypass grafting

Objectives:To compare the effects of propofol and nitroglycerine (NTG) on the efficacy of rewarming, extra volume added during cardiopulmonary bypass and extravascular lung water (EVLW) in patients undergoing on-pump coronary artery bypass grafting.Materials and Methods:A prospective, randomized, blinded trial, twenty adult patients were randomly assigned to receive either NTG infusion (NTG group) or propofol infusion (propofol group) during rewarming.Results:After drop in temperature at the end of surgery and till 24 h were significantly less in propofol group compare to NTG group (P < 0.025). Extra volume added during cardiopulmonary bypass and net crystalloid balance till 24 h was less in the propofol group (P < 0.003). There was no difference in EVLW and postoperative outcome.Conclusions:Propofol use during moderate hypothermic cardiopulmonary bypass is associated with less after drop in temperature and less requirement of extra fluid during the perioperative period.

Oral propranolol premedication and hypotensive anesthesia in shoulder arthroscopic surgery: a randomized controlled double-blind study

Objective The current study tested whether premedication with oral propranolol (10 mg) before hypotensive anesthesia in shoulder arthroscopic surgery could diminish reflex tachycardia following endotracheal intubation and nitroglycerine (NTG) infusion, the amount of NTG used, and the minimum alveolar concentration (MAC) values of inhalational anesthetic used during hypotensive anesthesia for shoulder arthroscopic surgery. Patients and methods A total of 60 American Society of Anesthesiologists (ASA) I patients scheduled for shoulder arthroscopic surgery were included in this randomized controlled double-blinded study on oral propranolol (10 mg) or placebo as a premedication 1 h before the induction of anesthesia. Hemodynamic variables, the amount of NTG, and the MAC values of inhalational anesthetic used were recorded. Visual field visibility by the surgeon using visual analogue score was assessed. Results The heart rate, amount of NTG, and the MAC values of sevoflurane used were highly significantly lower ( P P > 0.05) was found in the visual analogue score of the surgeon between the two groups. No statistically significant complications were observed in either group. Conclusion Premedication with 10 mg of oral propranolol before shoulder arthroscopic surgery was effective in achieving hypotensive anesthesia. It reduced reflex tachycardia, decreased NTG, and sevoflurane consumption without recorded complications.

A comparative study of dexmedetomidine, magnesium sulphate, or glyceryl trinitrate in deliberate hypotension during functional endoscopic sinus surgery

Context Induced hypotension to minimize bleeding during functional endoscopic sinus surgery (FESS) is of vital importance to the surgeon and anesthetist to decrease the risk of complications as well as procedural failure. Aim This study was designed to compare the efficacy of dexmedetomidine, magnesium sulfate, or glyceryl trinitrate in inducing deliberate hypotension during FESS and their effect on postoperative recovery, discharge, and postoperative analgesic requirement. Settings and design This was a randomized prospective single-blind study. Patients and methods Sixty patients of ASA physical status I or II scheduled for FESS were equally randomly assigned into three groups. The glyceryl trinitrate group (the G group) received glyceryl trinitrate infusion of 2-10 μg/kg/min. The dexmedetomidine group (the DEX group) received dexmedetomidine bolus of 1 μg/kg, followed by 0.2-0.7 μg/kg/h infusion for maintenance, and the magnesium sulfate group (the M group) received a bolus of 50 mg/kg magnesium sulfate, followed by infusion of 15 mg/kg/h for maintenance. The target mean arterial pressure was 55-65 mmHg. Hemodynamic parameters, blood lose, surgical field quality, intraoperative atropine, ephedrine or fentanyl use, emergence time, time to achieve an Aldrete score of 9 or greater, sedation score, time of discharge from postanesthesia care unit, and time to first analgesic request were recorded. Results The studied drugs achieved the target mean arterial pressure (55-65 mmHg) with superior hemodynamic stability in the DEX group. Intraoperative blood lose and quality of the surgical field were comparable. Both dexmedetomidine and magnesium sulfate offered the advantage of inherent analgesic and sedative effect, but at the expense of longer recovery of anesthesia and discharge from postanesthesia care unit. Conclusion Dexmedetomidine, magnesium sulfate, or glyceryl trinitrate induced deliberate hypotension, with superior hemodynamic stability in dexmedetomidine. Analgesic and sedative effects were obtained with dexmedetomidine and magnesium sulfate, but with longer recovery and discharge times.

Riboflavin and vitamin E increase brain calcium and antioxidants, and microsomal calcium-ATP-ase values in rat headache models induced by glyceryl trinitrate.

The essential use of riboflavin is the prevention of migraine headaches, although its effect on migraines is considered to be associated with the increased mitochondrial energy metabolism. Oxidative stress is also important in migraine pathophysiology. Vitamin E is a strong antioxidant in nature and its analgesic effect is not completely clear in migraines. The current study aimed to investigate the effects of glyceryl trinitrate (GTN)-sourced exogen nitric oxide (NO), in particular, and also riboflavin and/or vitamin E on involved in the headache model induced via GTN-sourced exogen NO on oxidative stress, total brain calcium levels, and microsomal membrane Ca(2+)-ATPase levels. GTN infusion is a reliable method to provoke migraine-like headaches in experimental animals and humans. GTN resulted in a significant increase in brain cortex and microsomal lipid peroxidation levels although brain calcium, vitamin A, vitamin C, and vitamin E, and brain microsomal-reduced glutathione (GSH), glutathione peroxidase (GSH-Px), and plasma-membrane Ca(2+)-ATPase values decreased through GTN. The lipid peroxidation, GSH, vitamin A, β-carotene, vitamin C, and vitamin E, and calcium concentrations, GSH-Px, and the Ca(2+)-ATPase activities were increased both by riboflavin and vitamin E treatments. Brain calcium and vitamin A concentrations increased through riboflavin only. In conclusion, riboflavin and vitamin E had a protective effect on the GTN-induced brain injury by inhibiting free radical production, regulation of calcium-dependent processes, and supporting the antioxidant redox system. However, the effects of vitamin E on the values seem more important than in riboflavin.

Efficacy of different dexmedetomidine regimens in producing controlled hypotensive anesthesia during functional endoscopic sinus surgery

BackgroundThe study was designed to assess the ability of dexmedetomidine in different regimens to produce controlled hypotensive anesthesia during functional endoscopic sinus surgery in adults and the need to add an additional hypotensive agent in the form of nitroglycerin to achieve the target MAP.MethodsIn this blinded randomized controlled trail, 45 Patients, aged from 18 to 50 years, ASA physical status I and II, underwent endoscopic sinus surgery were enrolled in the study. Before induction of GA, all patients received bolus dexmedetomidine 1 μ/kg iv more than 10 min. After induction, Patients were randomly allocated into three groups, group Dex-0.4, in which patients received dexmedetomidine infusion as 0.4 μg/kg/h, group Dex-0.8, in which patients received dexmedetomidine infusion as 0.8 μg/kg/h and group Dex-P, in which patients received saline infusion. The target MAP was 55–65 mmHg, if not achieved by the infused study drug, nitroglycerin infusion was added in a titrating manner started with 0.1 μg/kg/min and increased gradually till the target MAP is reached. The surgical field quality was assessed by using Fromme et al. bleeding score.ResultsThe intraoperative MAP in group Dex-P and group Dex-0.8 was maintained within target range at all time intervals. In group Dex-0.4, the MAP showed fluctuation to fall below and increased above the target range at different time intervals. Unlike the other two groups, no nitroglycerin infusion was needed in group Dex-0.8. Fromme et al. bleeding score showed the lowest values in Dex-0.8 group and the highest values in group Dex-0.4. The differences between the three groups were statistically significant with (P < 0.05).ConclusionDexmedetomidine as bolus 1 μg/kg iv followed by iv infusion of 0.8 μg/kg/h or dexmedetomidine as pre-induction bolus 1 μg/kg iv followed by nitroglycerine iv infusion significantly decreased the mean arterial blood pressure to target values and provide satisfactory field quality.

Navigating the 7 cs of certified practice.

Navigating the 7 cs of certified practice.

EHMTI-0234. Glyceryl trinitrate provoked mast cell degranulation is secondary to the release of nitric oxide in vivo

Infusion of the nitric oxide (NO) donor, glyceryl trinitrate (GTN), provokes a migraine-like attack in migraineurs and cFos up-regulation in rat trigeminal nucleus caudalis. We studied the level of dura mast cell degranulation after infusion of GTN in awake, freely moving rats and hypothesized that the degranulation is secondary to NO.

Abstracts from the 4th European Headache and Migraine Trust International Congress: EHMTIC 2014, September 18-21, 2014, Copenhagen, Denmark.

Background and aims Calcitonin gene-related peptide (CGRP) and glyceryl trinitrate (GTN) infusion in migr aineurs provokes headache resembling spontaneous migraine. GTN infusion model was transformed to rats causing expression of protein markers as a surrogate for headache. We hypothesized that CGRP infusion in awake rats would increase molecular markers of neuronal activation in migraine relevant tissues. Methods CGRP was infused intravenously in freely moving rats. c-fos mRNA in trigeminal nucleus caudalis (TNC) was analyzed by qPCR at different time points after CGRP and saline infusion. c-Fos and Zif268 stained nuclei were counted in the TNC. c-Fos-positive nuclei were also counted in the nucleus tractus solitaries (NTS) and caudal ventrolateral medulla (CVLM), integrative sites in the brain stem for processing cardiovascular signals. Protein expression of phosphorylated-extracellular signalregulated kinase (p-ERK), p-CREB and c-Fos was analysed in the dura mater, trigeminal ganglion and TNC samples using western blot. Results CGRP infusion caused a fall in blood pressure, and activated c-Fos in the NTS and CVLM in the brain stem. After 30 min of CGRP infusion, an increase in p-ERK was observed in the dura mater. But no activation of the neuronal activation markers, c-Fos and Zif269, was observed in the TNC. Conclusion CGRP infusion caused early activation of p-ERK in the dura mater but it did not increase immediate early genes in the TNC. Thus, systemic CGRP infusion substantially acts outside blood brain barrier and the peripheral activation doses not lead to the activation of second-order trigeminal neurons. No conflict of interest.

Impact of nitroglycerin infusion on weaning off hypertensive mechanically ventilated chronic obstructive pulmonary disease patients

IntroductionMechanical ventilation (MV) weaning trial can be compared to a cardiac stress test where spontaneous ventilation is a form of an exercise and therefore hemodynamic compromise can occur during the weaning process in critically ill patients. The combined increase in arterial pressure and heart rate during unsuccessful weaning is quite suggestive of weaning failure of cardiac origin. Assessment and prediction of weaning failure from cardiac origin remain complicated in patients with chronic obstructive pulmonary disease (COPD). Recent data showed that COPD itself is a powerful independent risk factor for cardiovascular morbidity and mortality, suggesting that occult cardiac dysfunction could be frequent in patients with COPD. The immediate transition from positive pressure mechanical ventilation to spontaneous ventilation may generate significant cardiopulmonary alterations that are complex and mainly include the inspiratory fall in intrathoracic pressure, the increase in work of breathing, and the catecholamine discharge that occur during abrupt transfer from mechanical ventilation to spontaneous breathing. Therefore, it could be suggested that a treatment targeting the cardiovascular system decreasing the preload might help the heart to tolerate the critical period of weaning more effectively. MethodsThis study was carried on 60 adult male and female patients admitted to the Critical Care Medicine Departments in the Alexandria Main University Hospital and who fulfilled the diagnosis of acute exacerbation of COPD according to the Global initiative for chronic obstructive lung disease (GOLD) [1], and considered eligible for weaning after at least 24h of invasive mechanical ventilation exhibiting systemic arterial hypertension during the start of spontaneous breathing trial. 30 of them were adult patients and served as the study group (Group I), and the other 30 were age-matched adults who served as the control group (Group II). Each group was subjected to spontaneous breathing trial (SBT) using a T-piece receiving FiO2 the same as during mechanical ventilation. Control group underwent SBT alone while the nitroglycerin group underwent continuous nitroglycerin infusion started at the beginning of the SBT and titrated to maintain normal arterial systolic blood pressure that is; 120–139mmHg). Hemodynamic, oxygenation and respiratory measurements were performed on the start of SBT, and after a 2-h T-piece SBT. ResultsCompared to the start of SBT, systolic arterial blood pressure and mean arterial blood pressure decreased [from (Mean±SD) 150.33±14.26, 112.56±9.37mmHg to 134.33±11.04, 92.78±5.81mmHg, respectively] in the nitroglycerin group, while the opposite occurred in the control group as systolic arterial blood pressure and mean arterial blood pressure increased [from (Mean±SD) 144.67±13.58, 109.78±10.09mmHg to 158.0±19.43, 114.73±10.82mmHg, respectively]. Mixed central venous saturation (ScvO2) decreased significantly in the control group at the end of SBT [from (Mean±SD) 71.90±1.84 to 69.25±2.20%], while in the nitroglycerin group, ScvO2 did not change at the end in comparison to the start of SBT [from (Mean±SD) 71.63±1.75 to 71.12±1.65%]. Nitroglycerin infusion at the start of SBT enabled a successful weaning from mechanical ventilation in 90% of patients in comparison to a successful weaning from mechanical ventilation of only 63.3% in the control group. ConclusionsNitroglycerin infusion might facilitate the weaning off hypertensive COPD patients by alleviating the cardiovascular compromise occurring during liberation from MV.

Model-based oscillometric blood pressure measurement: preliminary validation in humans.

We conceived new oscillometric blood pressure (BP) estimation methods based on physical modeling. The crux of these methods is to simultaneously estimate the arterial stiffness and BP of the patient from a standard oscillometric waveform. Hence, in contrast to previous methods, the BP estimation is specific to the patient at the time of measurement and is robust against arterial stiffening. We conducted initial testing of one of the methods against invasive reference brachial BP measurements in eight cardiac catheterization patients before and after nitroglycerin infusions. The method achieved systolic, diastolic and mean BP root-mean-squared-errors of 7.2, 7.6 and 6.7 mmHg. These errors were, on average, 40% lower than an existing high-end method.

Nitroglycerine and patient position effect on central, hepatic and portal venous pressures during liver surgery.

To reduce blood loss during liver surgery, a low central venous pressure (CVP) is recommended. Nitroglycerine (NG) with its rapid onset and offset can be used to reduce CVP. In this study, the effect of NG on portal and hepatic venous pressures (PVP and HVP) in different body positions was assessed. Thirteen patients undergoing liver resection were studied. Cardiac output (CO), mean arterial pressure (MAP) and CVP were measured. PVP and HVP were measured using tip manometer catheters at baseline (BL) in horizontal position; during NG infusion, targeting a MAP of 60 mmHg, with NG infusion and the patient placed in 10 head-down position. NG infusion reduced HVP from 9.7 ± 2.4 to 7.2 ± 2.4, PVP from 12.3 ± 2.2 to 9.7 ± 3.0 and CVP from 9.8 ± 1.9 to 7.2 ± 2.1 mmHg at BL. Head-down tilt during ongoing NG resulted in increases in HVP to 8.2 ± 2.1, PVP to 10.7 ± 3 and CVP to 11 ± 1.9 mmHg. CO at BL was 6.3 ± 1.1, which was reduced by NG to 5.8 ± 1.2. Head-down tilt together with NG infusion restored CO to 6.3 ± 1.0 l/min. NG infusion leads to parallel reductions in CVP, HVP and PVP at horizontal body position. Thus, CVP can be used to guide NG dosage and fluid administration at horizontal position. NG infusion can be used to reduce HVP. Head-down tilt can be used during NG infusion to improve both blood pressure and CO without substantial increase in liver venous pressure. In head-down tilt, CVP dissociates from HVP and PVP.

CGRP infusion in unanesthetized rats increases expression of c-Fos in the nucleus tractus solitarius and caudal ventrolateral medulla, but not in the trigeminal nucleus caudalis.

Calcitonin gene-related peptide (CGRP) and glyceryl trinitrate (GTN) infusion in migraineurs provokes headache resembling spontaneous migraine, and CGRP receptor antagonists are effective in the treatment of acute migraine. We hypothesized that CGRP infusion would increase molecular markers of neuronal activation in migraine-relevant tissues of the rat. CGRP was infused intravenously (i.v.) in freely moving rats to circumvent factors like anesthesia, acute surgery and severe hypotension, the three confounding factors for c-Fos expression. The trigeminal nucleus caudalis (TNC) was isolated at different time points after CGRP infusion. The level of c-Fos mRNA and protein expression in TNC were analyzed by qPCR and immunohistochemistry. c-Fos-stained nuclei were also counted in the nucleus tractus solitarius (NTS) and caudal ventrolateral medulla (CVLM), integrative sites in the brain stem for processing cardiovascular signals. We also investigated Zif268 protein expression (another immediate early gene) in TNC. The protein expression of p-ERK, p-CREB and c-Fos was analyzed in dura mater, trigeminal ganglion (TG) and TNC samples using Western blot. CGRP infusion caused a significant dose-dependent fall in mean arterial blood pressure. No significant activation of c-Fos in the TNC at mRNA and protein levels was observed after CGRP infusion. A significant increase in c-Fos protein was observed in the NTS and CVLM in the brain stem. Zif268 expression in the TNC was also not changed after CGRP infusion. p-ERK was increased in the dura mater 30 minutes after CGRP infusion. CGRP infusion increased the early expression of p-ERK in the dura mater but did not increase c-Fos and Zif268 expression in the TNC. The rats may, thus, differ from migraine patients, in whom infusion of CGRP caused headache and a delayed migraine attack. The rat CGRP infusion model with c-Fos or Zif268 as neuronal pain markers in TNC is unsuitable for antimigraine drug testing.

Angiotensin II receptor blocker telmisartan attenuates aortic stiffening and remodelling in STZ-diabetic rats.

BackgroundPrevention or attenuation of diabetic vascular complications includes anti-hypertensive treatment with renin-angiotensin system inhibitors on account of their protective effects beyond blood pressure reduction. The present study aimed to investigate the effects of telmisartan, an angiotensin II type 1 receptor blocker (ARB), on blood pressure, aortic stiffening, and aortic remodelling in experimental type 1 diabetes in rats.MethodsDiabetes was induced by streptozotocin (STZ) (65 mg/kg) in male Wistar rats. One diabetic group was treated for 10 weeks with telmisartan (10 mg/kg/day p/o). Pressure-independent aortic pulse wave velocity (PWV) was measured under anaesthesia after intravenous infusion of phenylephrine and nitroglycerine. Aortic wall samples were collected for histomorphometrical analysis.ResultsUntreated diabetes imposed differential effects on aortic stiffening, as demonstrated by increased isobaric PWV over a range of high blood pressures, but not at lower blood pressures. This was associated with loss and disruption of elastin fibres and an increase in collagen fibres in the aortic media. Treatment with telmisartan decreased resting blood pressure, reduced aortic stiffness, and partially prevented the degradation of elastin network within the aortic wall.ConclusionsTelmisartan improved the structural and functional indices of aortic stiffening induced by untreated STZ-diabetes, demonstrating the importance of ARBs in the therapeutic approach to diabetic vascular complications.

The effects of nitroglycerin, norepinephrine and aminophylline on intrapulmonary arteriovenous anastomoses in healthy humans at rest

We have investigated the effects of the intravenous infusion of nitroglycerin (NTG), norepinephrine (NE) and aminophylline (AMP) on the opening and recruitment of intrapulmonary arteriovenous anastomoses (IPAVA) in healthy humans at rest. In ten volunteers saline contrast echocardiography was performed during administration of two doses of the NTG (3μgkg−1min−1 and 6μgkg−1min−1) and NE (0.1μgkg−1min−1 and 0.25μgkg−1min−1) as well as 30min following the administration of AMP at rate of 6mgkg−1. Echocardiography was used to assign bubble scores (0–5) based on the number and spatial distribution of bubbles in the left ventricle. Doppler ultrasound was used to estimate pulmonary artery systolic pressure. Using a Finometer the following hemodynamic parameters were assessed: heart rate, stroke volume, cardiac output, total peripheral resistance as well as systolic, diastolic and mean arterial pressure. The most important finding from the current study was that nitroglycerin, norepinephrine and aminophylline in the applied doses were not found to promote IPAVA opening in healthy humans at rest.

The effect of nitric oxide on blockade of the norepinephrine transporter, uptake‐1, by methylphenidate (1145.6)

We previously showed that fresh synthesis of nitric oxide (NO) mediates transport of substrates across uptake ‐1, norepinephrine (NE), tyramine (T), mephentermine, ephedrine, imipramine and atomoxetine, and blockade by cocaine. Synthesis of NO was blocked by Nw‐nitro‐L‐arginine (L‐NNA) and the rise in arterial pressure it induces was restored to starting level by an infusion of nitroglycerin (NG), a NO donor. In this study we explored the role of NO synthesis on the blockade of uptake‐1 by methylphenidate (MP), a drug used in the treatment of attention deficit disorder, in Sprague Dawley rats in which mean arterial pressure was measured. NE (0.05, 0.1, 0.2 ug) with direct action on adrenergic receptors but is transported across uptake‐1 and sequestered in sympathetic nerve terminals, showed potentiation of its pressor effect after MP (1.52+/‐0.4 mg/kg) by 34%‐56% and not changed further after MP/L‐NNA/NG. The pressor effect of T (0,025, 0.05, 0.1 mg) which acts indirectly by entering across uptake‐1 to release NE, was reduced after MP by 78%‐85% and restored by 424% ‐650% after MP/L‐NNA/NG. The pressor effect of methoxamine, not a substrate of uptake‐1, was not affected by pretreatment with MP or MP/L‐NNA/NG. It is concluded that the blocking effect of MP on uptake‐1 is confirmed and this blockade is significantly dependent on synthesis of NO. Supported by the American University of Beirut.

Ranolazine as Treatment of Microvascular Coronary Dysfunction in a Woman With Signs and Symptoms of Ischemia but No Obstructive Coronary Artery Disease

Women often exhibit persistent symptoms, functional disability and a relatively high prevalence of microvascular coronary dysfunction (MCD) with no obstructive coronary artery disease (CAD) when evaluated for signs and symptoms of myocardial ischemia. A 27-year-old woman was referred by her treating cardiologist for symptoms of persistent chest pain for 10 years. Cardiac catheterization showed normal coronary arteries. Given the constellation of persistent chest pain and no obstructive CAD, a diagnosis of MCD was suspected, and she underwent coronary reactivity testing (CRT) with intracoronary infusions of adenosine, acetylcholine and nitroglycerin to test nonendothelial- and endothelial-dependent, micro- and macro-vascular coronary function. CRT results were consistent with a diagnosis of MCD. The patient was started on ranolazine, with significant improvement in symptoms. Cardiac magnetic resonance imaging (CMRI) after 3 months of treatment demonstrated improvement in perfusion compared to baseline. J Med Cases. 2014;5(1):23-25 doi: http://dx.doi.org/10.4021/jmc1522w

Variant angina associated with myocardial bridging and obstructive sleep apnea syndrome after lumbar spine surgery.

Variant angina associated with myocardial bridging and obstructive sleep apnea syndrome after lumbar spine surgery.

Nitroglycerin reverts clinical manifestations of poor peripheral perfusion in patients with circulatory shock

IntroductionRecent clinical studies have shown a relationship between abnormalities in peripheral perfusion and unfavorable outcome in patients with circulatory shock. Nitroglycerin is effective in restoring alterations in microcirculatory blood flow. The aim of this study was to investigate whether nitroglycerin could correct the parameters of abnormal peripheral circulation in resuscitated circulatory shock patients.MethodsThis interventional study recruited patients who had circulatory shock and who persisted with abnormal peripheral perfusion despite normalization of global hemodynamic parameters. Nitroglycerin started at 2 mg/hour and doubled stepwise (4, 8, and 16 mg/hour) each 15 minutes until an improvement in peripheral perfusion was observed. Peripheral circulation parameters included capillary refill time (CRT), skin-temperature gradient (Tskin-diff), perfusion index (PI), and tissue oxygen saturation (StO2) during a reactive hyperemia test (RincStO2). Measurements were performed before, at the maximum dose, and after cessation of nitroglycerin infusion. Data were analyzed by using linear model for repeated measurements and are presented as mean (standard error).ResultsOf the 15 patients included, four patients (27%) responded with an initial nitroglycerin dose of 2 mg/hour. In all patients, nitroglycerin infusion resulted in significant changes in CRT, Tskin-diff, and PI toward normal at the maximum dose of nitroglycerin: from 9.4 (0.6) seconds to 4.8 (0.3) seconds (P <0.05), from 3.3°C (0.7°C) to 0.7°C (0.6°C) (P <0.05), and from [log] -0.5% (0.2%) to 0.7% (0.1%) (P <0.05), respectively. Similar changes in StO2 and RincStO2 were observed: from 75% (3.4%) to 84% (2.7%) (P <0.05) and 1.9%/second (0.08%/second) to 2.8%/second (0.05%/second) (P <0.05), respectively. The magnitude of changes in StO2 was more pronounced for StO2 of less than 75%: 11% versus 4%, respectively (P <0.05).ConclusionsDose-dependent infusion of nitroglycerin reverted abnormal peripheral perfusion and poor tissue oxygenation in patients following circulatory shock resuscitation. Individual requirements of nitroglycerin dose to improve peripheral circulation vary between patients. A simple and fast physical examination of peripheral circulation at the bedside can be used to titrate nitroglycerin infusion.

Snakebite and severe hypertension: Looking for the Holy Grail

Sir The informative case report by Ahmed et al.[1] made us realize the clinical importance of elevated blood pressure in snake bite, recall pathogenesis, and revive educational aspects, based on our earlier experiences.[2] From the description made by the authors,[1] the offending snake in this report is likely to be krait. In developing countries where snakebites are ubiquitous, it is worth considering krait bite if pain abdomen precedes paralysis. The third “P” denotes potassium level, which invariably is low in many cases.[3] Also, in a given clinical setting with elevated BP in a child with a background history of paralysis following pain abdomen, without any renal manifestations or antecedent history of encephalitis, bulbar poliomyelitis, or Guillain Barre Syndrome, one has to include krait bite in the differential diagnosis. In addition to the reasons stated by the authors for elevated BP, other mechanisms are neuromuscular blockade at bulbar level, neurotoxin venom–induced release of catecholamines, decreased parasympathetic stimulation, and dysautonomia.[3] Slow recovery in this child.[1] may be attributable to delay in administration of anti snake venom and irreversible binding of venom to presynaptic receptor, as recovery occurs only with the generation of new neuromuscular junctions. Therapeutically though nitroglycerin infusion was beneficial, usefulness of angiotensin-converting-enzyme (ACE) inhibitors in hypertension due to snake bite was documented earlier.[4] Practitioners and emergency physicians have to avoid beta-blockers in snake venom–induced hypertension, as these agents are likely to precipitate severe alpha-agonist effects via the blockage of beta-receptor effects.[2] The mechanism for snakebite-induced hypertension, importance of recognizing this entity in acute-onset hypertension in the emergency room, differentiating this from other causes of secondary hypertension, and the need for administration of anti snake venom should be instilled in the minds of students of health sciences, and incorporated in teaching and training programs. Overall, early recognition and appropriate management with the anti snake venom and supportive measures not only save the patient[5] but also prevent further progression or deterioration of clinical status, since hypertension due to snake bite is completely reversible.

Prognostic implication of the coronary microvascular dysfunction in patients with isolated left bundle branch block

The present study aims to determine the influence of microvascular dysfunction (MVD) in the prognosis of patients presenting isolated left bundle branch block (LBBB). Methods: We studied 30 patients (pts), 22 males, 8 females, mean age 57 ± 4 years, with isolated LBBB, with a mean follow up of 48 ± 6 months. The control group consisted of 20 healthy individuals, 12 males, mean age 52 ± 10 years. Both groups were screened for cardiovascular risk factors (RF); they also had an echocardiogram and Coronary CT Scan, ruling out both structural heart disease and obstructive lesions of the epicardial coronary arteries. A myocardial perfusion study was then performed, with two groups emerging according to these results: Group A, 8 pts (26%), with reversible perfusion defects, in which the diagnosis of MVD was suspected, and Group B, 22 pts (74%), with either normal perfusion or minor septal/apical reversible defects (related to LBBB). All Group A pts, and 9 of the Group B pts, underwent coronary arteriography, with intracoronary acetylcholine and nitroglycerine infusion, thus evaluating vasomotor response as endothelium dependent (acetylcholine) or endothelium independent (nitroglycerine). During follow up, we reviewed functional class, 12 lead ECG and echocardiogram on a yearly basis. Results: All Group A patients had an abnormal acetylcholine response; only three of them had abnormal response to nitroglycerine infusion, suggesting endothelium dependent MVD. Of those in Group B, only one patient had abnormal acetylcholine response. At the end of the follow up period, 3 pts (37%) in Group A, showed functional class decrease vs 5 pts (22%) of those in Group B. In Group A, a significant increase of End Diastolic Left Ventricle Diameter (EDLVD) was found (51.6 ± 3.6 vs 59.3 ± 6.8 mm; p variation. In neither group major complications (death, heart failure admissions) were found. Conclusion: We confirm the association between MVD and a worse clinical prognosis in isolated LBBB patients. Repeated ischemia and myocardial fibrosis are highlighted as possible physiopathological mechanisms, precluding a progressive left ventricular function decrease, with a higher mortality and arrhythmia risk. Endothelial function preserving strategies, both preventive and therapeutic, might be useful in improving LBBB with MVD patient’s prognosis.