Exploring Horizons in the Treatment of Vasoplegia in Shock Syndromes

Vasoplegic endothelial dysfunction stands out as one of the most prominent shock syndromes in the intensive care unit, and despite continual therapeutic advances, it is still associated with poor prognosis in critical cases. This scenario is compatible with a significant inflammatory disturbance, with a propensity for increased vascular permeability and deterioration of endothelial response to modulators: a microcirculation disaster. The hemodynamic support's backbone is based primarily on fluid replacement and the use of vasopressor and inotropic agents in nonresponsive patients, aiming to establish a mean arterial pressure of at least 65 mmHg and therefore promote adequate tissue reperfusion. The present study's primary target is to discuss the combination of 3 concepts as a useful strategy for improving results against the high rates of mortality in critically ill patients. These 3 concepts are (1) the use of "broad-spectrum vasopressors," (2) vasopressorsparing strategy, and (3) microcirculation protection.

Methylene Blue to Neonatal Septic Shock treatment in neonate pigs. Clinics (Sao Paulo) 2022;77:100139. [PMID: 36459779 PMCID: PMC9706526 DOI: 10.1016/j.clinsp.2022.100139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

OBJECTIVE

The authors design an animal model of neonatal sepsis to analyze the treatment of neonatal septic shock with Methylene Blue (MB) in a swine model.

METHODS

The study design included twenty male newborn pigs divided into four groups: 1) The control group; 2) The sepsis group (induced with lipopolysaccharide); 3) The MB group, and 4) The MB-treated sepsis group. Septic shock was defined as Blood Pressure (BP) dropping 20% below the baseline value. Continuous Blood Pressure (BP), Nitric Oxide (NO) levels, cyclic Guanosine Monophosphate (cGMP), malondialdehyde acid, base excess, lactate, arterial blood gases, hematocrit, and echocardiography were analyzed.

RESULTS

The BP of the sepsis group treated with MB showed a slight improvement in the first hour after treatment; however, a significant difference was not observed compared to the untreated sepsis group. Besides hemodynamic stability, the current study did not show symptomatic pulmonary hypertension, suggesting that MB was safe in neonates and children. An improvement in Base Excel (BE) levels after MB administration in septic animals may indicate a possible improvement in microcirculation.

CONCLUSION

The MB improved biomarkers related to septic shock prognosis, although an improvement in the blood levels could not be detected. MB might be a beneficial drug for hemodynamic instability in infants.

Oral glutamine dipeptide or oral glutamine free amino acid reduces burned injury progression in rats

This study was carried out to evaluate the effect of Glutamine, as a dipeptide or a free amino acid form, on the progression of burn injuries in rats. Thirty male Wistar rats were burned with a comb metal plate heated in boiling water (98 °C) for three minutes, creating four rectangular full-thickness burn areas separated by three unburned interspaces (zone of stasis) in both dorsum sides. The animals were randomized into three groups (n=10): saline solution (G1-Control) and treated groups that orally received Glutamine as dipeptide (G2-Dip) or free amino acid (G3-FreeAA). Two and seven days after burn injury, lesions were photographed for unburned interspaces necrosis evolution assessment. Seven days after injury, glutathione seric was measured and histopathological analysis was performed. By photographs, there was a significant reduction in necrosis progression in G3-Free-AA between days two and seven. Histopathological analysis at day 7 showed a significantly higher stasis zone without necrosis and a higher number of fibroblasts in G2-Dip and G3-FreeAA compared with G1-Control. Also, glutathione serum dosage was higher in G2-Dip. The plasmatic glutathione levels were higher in the G2-Dip than the G1-Control, and there was a trend to higher levels in G3-FreeAA. The reduction in histological lesions, greater production of fibroblasts, and greater amounts of glutathione may have benefited the evolution of burn necrosis, which showed greater preservation of interspaces.

Atrial Septal Aneurysm and Atrial Septal Defect Association - an Uncommon But Well- Recognized Association

Atrial septal aneurysm (ASA) is an uncommon but wellrecognized cardiac abnormality. This educational text reviews the case of a 54-year-old female presenting an ASA related to a small ostium secundum atrial septal defect. The considerable signs and symptoms, interestingly, have not been justified by the clinical and hemodynamic investigations. So, we opted for a better imaging investigation with cardiac catheterization and transesophageal echocardiography. The surgical process was earlier indicated and performed with aid of cardiopulmonary bypass.

Frailty Among Non-Elderly Patients Undergoing Cardiac Surgery

Fundamento:

Geralmente vista como uma característica da velhice, a fragilidade também pode ocorrer em pessoas não idosas, principalmente naquelas que sofrem de doenças crônicas. A fragilidade pode aumentar o risco operatório.

Objetivos:

Determinar a prevalência de fragilidade em pacientes submetidos à cirurgia de revascularização do miocárdio (CRM) e/ou troca ou reconstrução valvar e/ou cirurgia valvar, bem como a influência da fragilidade nos desfechos pós-operatórios.

Métodos:

Nosso estudo incluiu 100 adultos que foram submetidos a operações cardíacas eletivas consecutivas. A fragilidade foi avaliada por meio da escala de Fried. Os pacientes também realizaram um teste de caminhada de 6 minutos, e medimos as pressões inspiratória e expiratória máximas. Um valor de p < 0,05 foi considerado significativo.

Resultados:

De uma coorte de 100 pacientes, com base nos critérios de fragilidade de Fried, 17 pacientes (17%) foram considerados frágeis, 70 (70%) pré-frágeis e apenas 13 (13%) não frágeis. Entre os portadores de valvopatia, 11 (18,6%) foram considerados frágeis e 43 (73%) pré-frágeis. Cinquenta e três por cento dos pacientes considerados frágeis tinham menos de 60 anos (mediana=48 anos). As diferenças no fenótipo de fragilidade entre os pacientes com valvopatia e doença arterial coronariana não foram estatisticamente significativas (p=0,305). A comparação entre pacientes não frágeis, pré-frágeis e frágeis não mostrou diferença significativa na distribuição das comorbidades e do estado funcional cardíaco, independentemente da doença cardíaca. No entanto, a mortalidade hospitalar mostrou-se significativamente maior em pacientes frágeis (29,4%, p=0,026) que em pacientes pré-frágeis (8,6%) e não frágeis (0%).

Conclusões:

A fragilidade é prevalente mesmo entre pacientes não idosos submetidos a CRM ou cirurgia cardíaca valvar e está associada a maior mortalidade hospitalar pós-operatória.

Effect of Diterpene Manool on the Arterial Blood Pressure and Vascular Reactivity in Normotensive and Hypertensive Rats

BACKGROUND

Many studies have shown that the diterpenoid classes exert a significant effect on the cardiovascular system. Diterpenes, in particular, are among the main compound links to cardiovascular properties such as vasorelaxant, inotropic, diuretic and hypotensive activity. While the manool vasorelaxation mechanism is visible, its effect on blood pressure (BP) is still unknown.

OBJECTIVE

To evaluate the in vivo hypotensive effect of manool and check the ex vivo vasorelaxation effect in rat aortic rings.

METHODS

The animals were divided randomly into two groups: normotensive and hypertensive. The normotensive group was sham-operated, and the 2K1C model was adopted for the hypertensive group. Invasive BP monitoring was performed for manool tests at different doses (10, 20 and 40 mg/kg). Concentration-response curves for manool were obtained in the aorta rings, with endothelium, pre-contracted with phenylephrine (Phe) after incubation with Nω-nitro-L-arginine methyl ester(L-NAME) or oxadiazole [4,3-a]quinoxalin-1-one (ODQ). Nitric oxide (NOx) plasma levels were measured by chemiluminescence assay.

RESULTS

After manool administration, BP was reduced in normotensive and hypertensive groups, and this effect was inhibited by L-NAME in hypertensive animals only in 10 mg/kg dose. Ex vivo manool promoted vasorelaxation, which was inhibited by L-NAME and ODQ incubation or endothelium removal. NOx plasma levels increased in the hypertensive group after manool administration. Manool elicits endothelium-dependent vascular relaxation in rat aorta mediated by the NO/cGMP signaling pathway and BP reduction, also by NOx plasma increase. These combined effects could be involved in modulating peripheral resistance, contributing to the antihypertensive effect of diterpene.

CONCLUSION

These effects together could be involved in modulating peripheral resistance, contributing to the antihypertensive effect of diterpene.

Effects of NO/cGMP inhibitors in a rat model of anaphylactoid shock

Anaphylactic shock can be defined as an acute syndrome, and it is the most severe clinical manifestation of allergic diseases. Anaphylactoid reactions are similar to anaphylactic events but differ in the pathophysiological mechanism. Nitric oxide (NO) inhibitors during anaphylaxis suggest that NO might decrease the signs and symptoms of anaphylaxis but exacerbate associated vasodilation. Therefore, blocking the effects of NO on vascular smooth muscle by inhibiting the guanylate cyclase (GC) would be a reasonable strategy. This study aimed to investigate the effects of NO/cGMP pathway inhibitors methylene blue (MB), N^ω-nitro-L-arginine methyl ester hydrochloride (L-NAME), and indigo carmine (IC) in shock induced by compound 48/80 (C48/80) in rats. The effect was assessed by invasive blood pressure measurement. Shock was initiated by C48/80 intravenous bolus injection 5 min before (prophylactic) or after (treatment) the administration of the inhibitors MB (3 mg/kg), L-NAME (1 mg/kg), and IC (3 mg/kg). Of the groups that received drugs as prophylaxis for shock, only the IC group did not present the final systolic blood pressure (SBP) better than the C48/80 group. Regarding shock treatment with the drugs tested, all groups had the final SBP similar to the C48/80group. Altogether, our results suggested that inhibition of GC and NO synthase in NO production pathway was not sufficient to revert hypotension or significantly improve survival.

Right Atrium Tumor Extension Through the Inferior Vena Cava. Considerations About Nine Cases Operated Under Cardiopulmonary Bypass

Introduction

Adrenocortical and renal cell carcinomas rarely invade the right atrium (RA). These neoplasms need surgical treatment, are very aggressive and have poor prognostic and surgical outcomes.

Case series

We present a retrospective cohort of nine cases of RA invasion through the inferior vena cava (four adrenocortical carcinomas and five renal cell carcinomas). Over 13 years (2002-2014), nine patients were operated in collaboration with the team of urologists. Surgery was possible in all patients with different degrees of technical difficulty. All patients were operated considering the imaging examinations with the aid of CPB. In all reported cases (renal or suprarenal), the decision to use CPB with deep hypothermic circulatory arrest (DHCA) on surgical strategy was decided by the team of urological and cardiac surgeons.

Conclusion

Data retrospectively collected from patients of public hospitals reaffirm: 1) Low incidence with small published series; 2) The selected cases did not represent the whole historical casuistry of the hospital, since they were selected after the adoption of electronic documentation; 3) Demographic data and references reported in the literature were presented as tables to avoid wordiness; 4) The series highlights the propensity to invade the venous system; 5) Possible surgical treatment with the aid of CPB in collaboration with the urology team; 6) CPB with DHCA is a safe and reliable option; 7) Poor prognosis with disappointing late results, even considering the adverse effects of CPB on cancer prognosis are expected but not confirmed.

In vitro evidence that endothelium-dependent vasodilatation induced by clozapine is mediated by an ATP-sensitive potassium channel

BACKGROUND

There is a definite association between antipsychotic drugs and arterial hypertension. However, endothelium functions are scarcely considered. This investigation was carried out to study the mechanisms involved in clozapine endothelium-dependent vascular reactivity.

METHODS

The experimental animals were male Wistar rats with a mean age of 70-90 days (250-300 g). The endothelium-dependent vascular reactivity was studied by measuring the isometric force and then constructing clozapine concentration-response curves. The force registrations were obtained in the aorta rings with and without the endothelium precontracted with phenylephrine (PE10^-6M) treatment; this followed incubation for 30 min in "organ chambers" with different inhibitors: l- NAME (nitric oxide/cGMP); indomethacin (PGI2/cAMP); tetraethylammonium (TEA), and specific hyperpolarization blockers (paxillin, apamin, glibenclamide). The data were presented as the mean ± standard error of the mean (SEM) and were compared by one-way ANOVA or two-way ANOVA followed by the Bonferroni post-test.

RESULTS

The primary outcomes were: 1) Clozapine-induced endothelium-dependent relaxation was not inhibited by indomethacin, l-NAME, ODQ, and methylene blue (MB); 2) The combination of l-NAME + indomethacin partially prevented the relaxation; 3) Clozapine did not induce relaxation in vessels contracted with KCl; 4) TEA did not block the clozapine-induced relaxation in vessels precontracted with PE (10^-6 M); 5) The potassium channel blockers paxillin and apamin did not prevent relaxation but glibenclamide did.

CONCLUSION

Concerning the mechanisms involved in clozapine endothelium-dependent vascular reactivity, the present study suggests that there is synergistic participation that probably occurs through a crosstalk mechanism of the cAMP, cGMPpathways and hyperpolarization.

Methylene Blue for Refractory Shock in Polytraumatized Patient: A Case Report

BACKGROUND

Methylene blue (MB) has been advocated for the treatment of shock refractory to standard measures. MB is proposed to increase blood pressure in shock by interfering with guanylate cyclase and nitric oxide synthase (NOS) activity. Several studies have evaluated the vasoconstrictive and positive inotropic effects of MB in septic shock patients. However, there is a paucity of studies involving trauma patients.

CASE REPORT

A 4-year-old boy was hit by a truck while riding his bicycle and was treated with fluid resuscitation at the emergency department and then taken to the operating room for damage-control surgery. He had liver, diaphragm, rectal, and thoracic injuries. At the pediatric intensive care unit (PICU), he remained hypotensive despite volume, dopamine, epinephrine, and norepinephrine infusion. A dose of 0.5 mg/kg of i.v. MB was administered. During the next 2 h after MB administration, we were able to wean him off norepinephrine, and doses of epinephrine and dopamine were reduced. Ultimately, he was discharged from the PICU 13 days later in good condition. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Trauma patients who have experienced bleeding and survived the initial insult are still at risk of dying from continuing systemic hypoperfusion and the resultant multiple organ dysfunctions. Use of a low dose of MB as an adjuvant to treat shock might improve survival of these patients.

Effect of rosmarinic acid on the arterial blood pressure in normotensive and hypertensive rats: Role of ACE

BACKGROUND

In recent years, it has been demonstrated the inhibitory effect of some plant species on the angiotensin-converting enzyme and rosmarinic acid is a prominent constituent of these species.

HYPOTHESIS/PURPOSE

This study was carried out to verify the effect of rosmarinic acid on blood pressure through inhibitory activity on angiotensin-converting enzyme in rats.

STUDY DESIGN

The arterial hypertension was promoted using 2-kidneys 1-clip model in rats. The potential inhibitory rosmarinic acid effect on angiotensin-converting enzyme activity was compared with captopril actions by analyzing in vivo blood pressure dose-response curves to angiotensin I and bradykinin. The in vitro plasma angiotensin-converting enzyme activity was measured by fluorimetry using the substrate Abz-FRK(Dnp)P-OH substrate. In addition, dosages of nitrite/nítrate analysis were carried out.

RESULTS

(1) rosmarinic acid caused systolic blood pressure dose-dependent decrease in hypertensive rats; (2) The angiotensin I dose-response curves demonstrated that rosmarinic acid promotes minor changes in systolic blood pressure only in the hypertensive group; (3) The bradykinin dose-response curves showed that both rosmarinic acid and captopril promoted a systolic blood pressure reduction, but only the captopril effect was significant; (4) The angiotensin-converting enzyme activity in rat lung tissue was inhibited by the rosmarinic acid in a dose dependent manner; (5) The analysis of nitrite/nítrate plasma concentrations showed no significant difference among the experimental groups.

CONCLUSION

The rosmarinic acid is effective in reducing blood pressure, selectively, only in hypertensive animals. The rosmarinic acid (173µM) promoted almost a 98.96% reduction on angiotensin-converting enzyme activity.

The Left Atrial Appendage Revised

Nonvalvular atrial fibrillation is associated with a 4- to 5-fold strokes increase and may be responsible for 15% to 20% of all strokes in the elderly. In this scenario, the left atrial appendage thrombus would be the associated with 90% of cases. The use of anticoagulants, percutaneous devices, and the left atrial appendage surgical exclusion is still an open discussion. For left atrial appendage procedures, relevant anatomic spatial relationships have to be emphasized, besides the chance of the normal physiological functioning would be eliminated with the proceedings. There are evidences that the left atrial appendage closure during routine cardiac surgery is significantly associated with an increased risk of early postoperative atrial fibrillation. Therefore, the purpose of this review is to focus basic aspects for continuous medical education. In summary, the rationale of this text is to emphasize anatomical and pharmacological aspects involved in the simple surgical exclusion of left atrial appendage under cardiopulmonary bypass. There are several operative techniques, but to conclude this revision it will present one of them based on the discussed basic sciences.

The Diterpene Sclareol Vascular Effect in Normotensive and Hypertensive Rats

BACKGROUND:

The diterpene Sclareol has antimicrobial action, cytotoxic and cytostatic effects and anti-tumor activities. However, researches on the cardiovascular system are scarce.

OBJECTIVE:

This study was designed to investigate the mechanisms involved in the Sclareol cardiovascular effect in normotensive and hypertensive rats.

METHODS:

The arterial hypertension was promoted using 2-kidneys 1-clip model in rats. The effect of sclareol on blood pressure was performed by using three dose (10, 20 and 40 mg/kg). Cumulative dose-response curves for Sclareol were determined for endothelium-intact and endothelium-denuded aortic rings in presence or absence of L-NAME and ODQ. The NOx levels were measure in the plasma sample.

RESULTS:

The Sclareol administration in vivo caused a significant reduction in blood pressure in both groups. In vitro the sclareol promoted relaxation in aorta, with endothelium, pre-contracted to Phe. The inhibitors of the nitric oxide synthase and soluble guanylate cyclase were as efficient as the removal of endothelium, in inhibiting the Sclareol-induced relaxation. Otherwise, it was no change of NOx. Also, for unknown reasons, the Sclareol is not selective for hypertensive animals.

CONCLUSION:

The diterpene Sclareol showed in vivo hypotensive and in-vitro vasodilator effects; The chemiluminescence plasmatic NO analysis showed no significant difference between groups and The Sclareol exhibit better effect on normotensive than hypertensive animals to reduce blood pressure. It is concluded that the diterpenes metabolites would be a promising source prototype for the development of new agents in the cardiovascular therapy.

FUNDAMENTO:

O diterpeno Esclareol tem ação antimicrobiana, efeitos citotóxicos e citostáticos e atividades antitumorais. No entanto, pesquisas sobre o sistema cardiovascular são escassas.

OBJETIVO:

Este estudo foi desenvolvido para investigar os mecanismos envolvidos no efeito cardiovascular de Esclareol em ratos normotensos e hipertensos.

MÉTODOS:

A hipertensão arterial foi promovida utilizando modelo de 2 clones de 1-clipe em ratos. O efeito do esclareol sobre a pressão arterial foi realizado utilizando três doses (10, 20 e 40 mg/kg). As curvas dose-resposta cumulativas para Esclareol foram determinadas para anéis aórticos endotélio-intactos e desprovidos de endotélio na presença ou ausência de L-NAME e ODQ. Os níveis de NOx foram medidos na amostra de plasma.

RESULTADOS:

A administração de Esclareol in vivo causou uma redução significativa na pressão sanguínea em ambos os grupos. In vitro o esclareol promoveu relaxamento na aorta, com endotélio, pré-contraído a Phe. Os inibidores da óxido nítrico sintase e da guanilato ciclase solúvel foram tão eficientes quanto a remoção do endotélio, na inibição do relaxamento induzido por Esclareol. Por outra parte, não houve mudança de NOx. Além disso, por razões desconhecidas, o Sclareol não é seletivo para animais hipertensos.

CONCLUSÃO:

O diterpeno Esclareol apresentou efeitos hipotensores in vivo e vasodilatadores in vitro; A análise de NO plasmático por quimioluminescência não mostrou diferença significativa entre os grupos e O Esclareol exibe melhor efeito sobre os animais normotensos do que hipertensos para reduzir a pressão arterial. Conclui-se que os metabólitos de diterpenos seriam um protótipo de fonte promissora para o desenvolvimento de novos agentes na terapia cardiovascular.

Bovine Pericardial Patch Augmentation of One Insufficient Aortic Valve Cusp with Twenty-three-year Positive Clinical Follow-up Independent of the Patch Degeneration

Scientific progress shall ultimately boost the current acceptance level for conservative aortic valve surgery. The present text aimed to report the 23-year long-term follow-up of one patient operated with bovine pericardium cusp extension. Growing confidence in the efficacy of the operation will allow a more expeditious indication for surgical treatment, as is already the case in mitral valve repair. This change of attitude will certainly make it possible for patients to be sent for operation in mild aortic valve regurgitation. The present report reinforces the concept and highlights the impression that the aortic valvoplasty, independent of the progressive bovine pericardium degeneration, may positively change the natural history of the aortic valve insufficiency.

Speculative Considerations about Some Cardiology Enigmas

Background:

Enigmas often lead to hypotheses and speculations. For this reason, especially for the sake of the reader’s motivation, we opted for the plain discussion of some cardiology enigmas.

Objective:

The present text was aimed to discuss speculatively some cardiology enigmas.

Method:

Text was freely designed in the context of coronary artery and heart valve diseases.

Results:

The results were presented as the combination enigma/hypothesis. 1) The absence of arteriosclerosis in intramyocardial coronary arteries/ endothelium-myocardial interaction (crosstalk); 2) The unique and always confirmed superior evolution of the internal thoracic artery as coronary graft/ higher NO basal release 3) The prophylactic left internal thoracic artery graft in mildly-stenosed coronary lesions/need of more accurate functional imaging techniques; 4) The high incidence of perioperative atrial fibrillation in patients with coronary artery disease/atrial ischemia associated to left circumflex coronary lesions; 5) The handling of disease-free saphenous vein grafts at the time of re-operation/biological serendipity with graft vein segments; 6) The possible aortic stenosis protection against coronary artery disease/ endothelium myocardium interaction (crosstalk) improving NO release.

Conclusion:

The discussed topics associated with their respective speculative hypothesis remain as enigmas, but would become motivations for investigations

Cardiopulmonary Bypass Ischemic Hepatitis Reported in Five Patients

Objective

In cardiac surgery, the lung, renal and neurological events are the most frequent complications. Less common, acute liver failure is a serious complication that adds high morbidity, mortality, and costs. Therefore, this communication aimed to retrospectively evaluate five patients who presented, in 2014, severe acute liver failure in the immediate postoperative period.

Methods

Retrospective data analysis of patients' medical records that showed severe liver failure has been computed in the medical records of five patients undergoing cardiac surgery at the Hospital da Faculdade de Medicina de Ribeirão Preto - USP in the immediate postoperative period from February 1, 2014 to December 12, 2014. The study selected five males patients, 60 to 67 years old, cardiopulmonary bypass mean time of 101.4 minutes (varying from 80 to 140 minutes), who presented acute perioperative liver failure.

Results

The five patients showed an impressive increase of blood transaminase (serum alanine aminotransferase), suggesting acute hepatitis. The evolution of all patients was catastrophic, with severe hemodynamic effects and death. Many studies suggest that systemic hypotension is an important pathogenic factor for ischemic hepatitis. However, our data and previous studies raise the possibility that other yet unknown factors other than hypotension may be part of the pathophysiology of cardiopulmonary bypass after ischemic hepatitis (anticoagulation inadequate for the quality of heparin and protamine, etc.).

Conclusion

Currently, there are no conclusive studies on the prevention of perioperative liver failure. More well-designed studies are needed on the introduction and evolution of liver dysfunction after cardiac surgery.

Use of Methylene Blue to Treat Hypovolemic Shock Followed by Ischemia-Reperfusion Injury in the Postoperative Orthotopic Liver Transplant Patient: A Case Report

A 57-year-old female patient received elective liver transplant due to nonalcoholic steatohepatitis complicated by hepatocellular carcinoma. Her preoperative Model for End-Stage Liver Disease score was 11. The total transplant ischemic time was 10 hours and 35 minutes, and the warm ischemic time was 35 minutes. Even with aggressive fluid overload and use of high concentrations of vasoactive amines, the patient developed possible primary graft dysfunction with poor response to fluids and vasopressor support, suggesting vasoplegic syndrome. On the basis of the hypothesis of vasoplegic syndrome, the patient received methylene blue intravenously (100 mg bolus for 12 h/1.5 mg/kg). The catastrophic situation was controlled. The patient's urine output markedly improved, she was subsequently weaned from vasoactive support, and mechanical ventilation was discontinued 2 days later. The patient was discharged on the 20th postoperative day.

In vitro reactivity ("organ chamber") of guinea pig tracheal rings-methodology considerations

The present text was motivated by the difficulties faced by our postgraduate students when using airways studies protocols and will take into consideration the three mechanisms of relaxation: (I) guanosine 3,5-cyclic monophosphate (cGMP)/NO-dependent; (II) adenosine 3,5-cyclic monophosphate (cAMP)/PGI2-dependent, and (III) hyperpolarization-dependent. Tracheal rings are studied in an organ bath containing a gassed physiological salt solution, usually at a temperature of 37 °C. An agent or procedure that causes contraction [acetylcholine (Ach) or metacholine] of the smooth muscle is needed before study airway dilator drugs. The presented airways studies protocols are useful to study the bronchial epithelial-dependent reactivity.

An adaptation for exhaled breath condensate collection in rabbits

AIM

To set up and test the feasibility of a handmade apparatus adapted for exhaled breath condensate (EBC) collection in medium-sized animals.

MATERIALS AND METHODS

The apparatus was produced using an 18-mm thick u-shaped borosilicate glass. The u-shaped tube body is 25 cm in diameter, and the horizontal portions are 12 cm in diameter. The base consists of a tube joint 14/20 or 14 mm thick by 20 cm in diameter, and has a length of 5 cm. This has a hole that is plugged for condensate flow to a 1.5 mL polypropylene microtube that stores the condensate during collection. Was placed inside a styrofoam box and immersed in crushed ice and salt to ensure cooling. The temperature was monitored and maintained throughout the collection at -10°C. One of the outputs of the u-shaped tube was connected to the expiratory limb of the ventilator.

RESULTS

An experimental model of ALI, induced by oleic acid (OA) was adopted to determine the concentration of biomarkers of oxidative stress: malondialdehyde (MDA), glutathione (GSH), and nitrite/nitrate (NOx). The proposed model allows measurement of NOx, MDA, and GSH. However, the NOx and MDA levels in the EBC were not significant. It was only possible to observe an upward trend, which suggests a temporal evolution of the presence of these markers in the EBC.

CONCLUSION

The EBC collection method adapted is effective to generate sufficient content that allows to determine the levels of different biomarkers, such as NOx, MDA, and GSH, that are involved in oxidative and inflammatory stress processes during respiratory diseases.

Protective Effect of Aortic Stenosis on the Coronary Arteries. Hypothetic Considerations to an Old Enigma

A literature overview of angiographic studies has shown that the prevalence of significant coronary disease in patients with aortic stenosis (AS) varies from 20 to 60%. Early necropsy studies suggested that patients with AS had a lower than expected incidence of coronary artery disease (CAD), originating the concept of a protective effect of AS on the coronary arteries. The myth of AS protection against CAD would be better explained as endothelium-myocardial interaction (crosstalk) protection triggered by left ventricular overload. Therefore, the cGMP/NO pathway induced by the AS overload pressure would explain the low incidence of CAD, which is compatible with the amazing natural long-term evolution of this cardiac valve disease.

Adjuvant Pericardial Sac Restraining in Heart Failure Treatment. A Medical Hypothesis Illustrated by a Case Report

Ventricular constraint therapy has been used to prevent and reverse the progression of heart failure in ischemic and nonischemic cardiomyopathies. We hypothesized that ventricular restraint should be tried by closing the pericardium that was previously opened following left ventricle topographical projection. The surgical technique presentation is illustrated by a remarkable 13-year outcome of one patient with dilated cardiomyopathy treated surgically by mitral prosthesis, Cox/Maze III surgery to treat atrial fibrillation, and associated to the ventricular constraint using the patient's own pericardium. The ventricular pericardial restraint role is unclear, since the patient had multiple corrections that could be responsible for the good outcome; however it is viable deserving investigations.

Effects of methylene blue in acute lung injury induced by oleic acid in rats

BACKGROUND

In acute lung injury (ALI), rupture of the alveolar-capillary barrier determines the protein-rich fluid influx into alveolar spaces. Previous studies have reported that methylene blue (MB) attenuates such injuries. This investigation was carried out to study the MB effects in pulmonary capillary permeability.

METHODS

Wistar rats were divided into five groups: (I) Sham: saline bolus; (II) MB, MB infusion for 2 h; (III) oleic acid (OA), OA bolus; (IV) MB/OA, MB infusion for 2 h, and at 5 min after from the beginning, concurrently with an OA bolus; and (V) OA/MB, OA bolus, and after 2 h, MB infusion for 2 h. After 4 h, blood, bronchoalveolar lavage (BAL), and lung tissue were collected from all groups for analysis of plasma and tissue nitric oxide, calculation of the wet weight to dry weight ratio (WW/DW), and histological examination of lung tissue. Statistical analysis was performed using nonparametric test.

RESULTS

Although favourable trends have been observed for permeability improvement parameters (WW/WD and protein), the results were not statistically significant. However, histological analysis of lung tissue showed reduced lesion areas in both pre- and post-treatment groups.

CONCLUSIONS

The data collected using this experimental model was favourable only through macroscopic and histological analysis. These observations are valid for both MB infusions before or after induction of ALI.

Acute but not chronic metabolic acidosis potentiates the acetylcholine-induced reduction in blood pressure: an endothelium-dependent effect

Metabolic acidosis has profound effects on vascular tone. This study investigated the in vivo effects of acute metabolic acidosis (AMA) and chronic metabolic acidosis (CMA) on hemodynamic parameters and endothelial function. CMA was induced by ad libitum intake of 1% NH4Cl for 7 days, and AMA was induced by a 3-h infusion of 6 M NH4Cl (1 mL/kg, diluted 1:10). Phenylephrine (Phe) and acetylcholine (Ach) dose-response curves were performed by venous infusion with simultaneous venous and arterial blood pressure monitoring. Plasma nitrite/nitrate (NOx) was measured by chemiluminescence. The CMA group had a blood pH of 7.15±0.03, which was associated with reduced bicarbonate (13.8±0.98 mmol/L) and no change in the partial pressure of arterial carbon dioxide (PaCO2). The AMA group had a pH of 7.20±0.01, which was associated with decreases in bicarbonate (10.8±0.54 mmol/L) and PaCO2 (47.8±2.54 to 23.2±0.74 mmHg) and accompanied by hyperventilation. Phe or ACh infusion did not affect arterial or venous blood pressure in the CMA group. However, the ACh infusion decreased the arterial blood pressure (ΔBP: -28.0±2.35 mm Hg [AMA] to -4.5±2.89 mmHg [control]) in the AMA group. Plasma NOx was normal after CMA but increased after AMA (25.3±0.88 to 31.3±0.54 μM). These results indicate that AMA, but not CMA, potentiated the Ach-induced decrease in blood pressure and led to an increase in plasma NOx, reinforcing the effect of pH imbalance on vascular tone and blood pressure control.

Twenty years of vasoplegic syndrome treatment in heart surgery. Methylene blue revised

Objective

This study was conducted to reassess the concepts established over the past 20 years, in particular in the last 5 years, about the use of methylene blue in the treatment of vasoplegic syndrome in cardiac surgery.

Methods

A wide literature review was carried out using the data extracted from: MEDLINE, SCOPUS and ISI WEB OF SCIENCE.

Results

The reassessed and reaffirmed concepts were 1) MB is safe in the recommended doses (the lethal dose is 40 mg/kg); 2) MB does not cause endothelial dysfunction; 3) The MB effect appears in cases of NO up-regulation; 4) MB is not a vasoconstrictor, by blocking the cGMP pathway it releases the cAMP pathway, facilitating the norepinephrine vasoconstrictor effect; 5) The most used dosage is 2 mg/kg as IV bolus, followed by the same continuous infusion because plasma concentrations sharply decrease in the first 40 minutes; and 6) There is a possible "window of opportunity" for MB's effectiveness. In the last five years, major challenges were: 1) Observations about side effects; 2) The need for prophylactic and therapeutic guidelines, and; 3) The need for the establishment of the MB therapeutic window in humans.

Conclusion

MB action to treat vasoplegic syndrome is time-dependent. Therefore, the great challenge is the need, for the establishment the MB therapeutic window in humans. This would be the first step towards a systematic guideline to be followed by possible multicenter studies.

High conductance potassium channels activation by acid exposure in rat aorta is endothelium-dependent

Background

We investigated, previously, the mechanism by which extracellular acidification promotes relaxation in rat thoracic aorta. These studies suggested that extracellular acidosis promotes vasodilation mediated by NO, K_ATP and SK_Ca, and maybe other K⁺ channels in isolated rat thoracic aorta. This study was carried out to investigate the paxilline-mediated hyperpolarization induced by acid exposure.

Results

The relaxation response to HCl-induced extracellular acidification (7.4–6.5) was measured in rat aortic rings pre-contracted with phenylephrine (PE, 10⁻⁶ M). The vascular reactivity experiments were performed in endothelium-intact and denuded rings, in the presence of paxilline (10⁻⁶ M), which is an inhibitor of high calcium conductance potassium BK_Ca channels. In rings with endothelium, paxilline inhibits relaxation, triggered by acidification at all pH values lower than 7.2 and had no effect on rings without endothelium, showing that the activation of BK_Ca is endothelium-dependent.

Conclusion

High conductance potassium channel activation induced by acid exposure is endothelium-dependent.

A variant technique for the surgical treatment of left ventricular aneurysms

Objective

To present a surgical variant technique to repair left ventricular aneurysms.

Methods

After anesthesia, cardiopulmonary bypass, and myocardial protection with hyperkalemic tepic blood cardioplegia: 1) The left ventricle is opened through the infarct and an endocardial encircling suture is placed at the transitional zone between the scarred and normal tissue; 2) Next, the scar tissue is circumferentially plicated with deep stitches using the same suture thread, taking care to eliminate the entire septal scar; 3) Then, a second encircling suture is placed, completing the occlusion of the aneurysm, and; 4) Finally, the remaining scar tissue is oversewn with an invaginating suture, to ensure hemostasis. Myocardium revascularization is performed after correction of the left ventricle aneurysm. The same surgeon performed all the operations.

Results

Regarding the post-surgical outcome 4 patients (40%) had surgery 8 eight years ago, 2 patients (20%) were operated on over 6 years ago, and 1 patient (10%) was operated on more than 5 years ago. Three patients (30%) were in functional class I, class II in 2 patients (20%) and 2 patients (20%) with severe comorbidities remains in class III of the NYHA. There were three deaths (at four days, 15 days and eight months) in septuagenarians with acute myocardial infarction, diabetes and pulmonary emphysema.

Conclusion

The technique is easy to perform, safe and it can be an option for the correction of left ventricle aneurysms.

Artificial phrenoesophageal ligament. An experimental study in dogs

This report deals with the preparation of a 'true' artificial phrenoesophageal ligament aimed at restoring effective anchoring of the esophagus to the diaphragm, keeping the esophagogastric sphincter in the abdomen. A total of 24 mongrel dogs were assigned to four groups: (i) Group I (n = 4): the esophageal diaphragm hiatus left wide open; (ii) Group II (n = 8): the anterolateral esophagus walls were attached to the diaphragm by the artificial ligament and the esophageal hiatus was left wide opened; (iii) Group III (n = 5): in addition to the use of the artificial ligament, the esophageal hiatus was narrowed with two retroesophageal stitches; (iv) Group IV (n = 7): the only procedure was the esophageal hiatus narrowing with two retroesophageal stitches. The phrenoesophagogastric connections were released, sparing the vagus nerves. Five animals of groups III and IV, which did not develop hiatal hernia, were submitted to esophageal manometry immediately before and 15 days after surgery. In group I, all animals developed huge sliding hiatal hernias. In group II, two dogs (25%) had a paraesophageal hernia between the two parts of the artificial ligament. In group III, neither sliding hiatal hernia nor paraesophageal hernia occurred. In group IV, two animals (28.6%) developed sliding esophageal hiatus hernia. Regarding esophageal manometry, postoperative significant difference between groups III and IV (P = 0.008) was observed. Thus, the artificial phrenoesophageal ligament maintained the esophagus firmly attached to the diaphragm in all animals and the esophagogastric sphincter pressure was significantly higher in this group.

Presentation of an experimental method to induce in vitro ("organ chambers") respiratory acidosis and its effect on vascular reactivity

PURPOSE

To create in vitro a model to generate acidosis by CO2 bubbling "organ chambers", which would be useful for researchers that aim to study the effects of acid-base disturbs on the endothelium-dependent vascular reactivity.

METHODS

Eighteen male Wistar rats (230-280 g) were housed, before the experiments, under standard laboratory conditions (12h light/dark cycle at 21°C), with free access to food and water. The protocol for promoting in vitro respiratory acidosis was carried out by bubbling increased concentrations of CO2. The target was to achieve an ideal way to decrease the pH gradually to a value of approximately 6.6.It was used, initially, a gas blender varying concentrations of the carbogenic mixture (95% O2 + 5% CO2) and pure CO2.

RESULTS

1) 100% CO2, pH variation very fast, pH minimum 6.0; 2) 90%CO2 pH variation bit slower, pH minimum 6.31; 3) 70%CO2, pH variation slower, pH minimum 6.32; 4) 50% CO2, pH variation slower, pH minimum 6:42; 5) 40 %CO2, Adequate record, pH minimum 6.61, and; 6) 30 %CO2 could not reach values below pH minimum 7.03. Based on these data the gas mixture (O2 60% + CO2 40%) was adopted.

CONCLUSION

This gas mixture (O2 60% + CO2 40%) was effective in inducing respiratory acidosis at a speed that made, possible the recording of isometric force.

Presentation of a needle for direct or percutaneous myocardium stem cells injection

The instrument has a locking mechanism and is composed of an external needle with blunt tip, with multiple 0.5 mm diameter holes. Internally it is fitted with a mandrill needle, which can be mobilized inside occluding or releasing the lateral holes. The procedure for producing micro lesions is done by exchanging the blunt mandrill for a brush-mandrill, provided with micro bristles that are structurally designed to fill the holes with small exteriorization of bristles. As an option to brush mandrill there is a second self-expandable feather shaped mandrill.

Evaluation of oxidative stress in the late postoperative stage of liver transplantation

INTRODUCTION

Liver transplant recipients are at an increased oxidative stress risk due to pre-existing hepatic impairment, ischemia-reperfusion injury, immunosuppression, and functional graft rejection. This study compared the oxidative status of healthy control subjects, patients with liver cirrhosis on the list for transplantation, and subjects already transplanted for at least 12 months.

PATIENTS AND METHODS

Sixty adult male patients, aged between 27 and 67 years, were subdivided into 3 groups: a control group (15 healthy volunteers), a cirrhosis group (15 volunteers), and a transplant group (30 volunteers). Oxidative stress was evaluated by activity of reduced glutathione, malondialdehyde, and vitamin E.

RESULTS

There was a significant difference (P < .01) in the plasma concentration of reduced glutathione in the 3 groups, with the lowest values observed in the transplanted group. The malondialdehyde values differed significantly (P < .01) among the 3 groups, with the transplanted group again having the lowest concentrations. The lowest concentrations of vitamin E were observed in patients with cirrhosis compared with control subjects, and there was a significant correlation (P < .05) among the 3 groups. No correlations were found between reduced glutathione and vitamin E or between vitamin E and malondialdehyde. However, there were strong correlations between plasma malondialdehyde and reduced glutathione in the 3 groups: control group, r = 0.9972 and P < .0001; cirrhotic group, r = 0.9765 and P < .0001; and transplanted group, r = 0.8981 and P < .0001.

CONCLUSIONS

In the late postoperative stage of liver transplantation, oxidative stress persists but in attenuated form.

Prevalence of heart disease demonstrated in 60 years of the Arquivos Brasileiros de Cardiologia

Considering the historical and academic relevance of the Brazilian Archives of Cardiology (ABC), as its MEDLINE indexing began in 1950, it was assumed as a hypothesis that the analysis of the publications over the last 60 years could reflect the changing trends of heart disease in Brazil.

The study data were collected using a program developed for this purpose, allowing the automatic extraction of information from the MEDLINE database. The study information were collected by searching "Brazilian Archives of Cardiology AND selected parameter in English". Four observational groups were determined: (1) major groups of heart diseases (coronary artery disease, valvular heart disease, congenital heart disease and cardiomyopathies); (2) relevant diseases in clinical practice (cardiac arrhythmias, cor pulmonale, myocardial infarction and congestive heart failure); (3) cardiovascular risk factors (hypertension, diabetes, dyslipidemia and atherosclerosis); and (4) group determined due to the growing trend of publications on congestive heart failure seen in previous groups (congestive heart failure, myocardial infarction, rheumatic heart disease and Chagasic heart disease)

All publications within the established groups were described, highlighting the increasing importance of heart failure and diabetes as risk factors. A relatively easy search was carried out, using the computer program developed for literature search covering six decades. Emphasizing the limitations of the study, we suggest the existence of an epidemiological link between cardiac diseases that are prevalent in Brazil and the publications of the Brazilian Archives of Cardiology.

Guanylate cyclase inhibition by methylene blue in circulatory shock caused by acute necrotizing pancreatitis: a word of caution based on a porcine model

OBJECTIVE

To study the therapeutic application of guanylate cyclase inhibition by methylene blue in an experimental model of acute pancreatitis in pigs.

METHODS

acute necrotizing pancreatitis was induced in anesthetized pigs by the retrograde infusion of 1 ml/kg of 5% sodium taurocholate and 8 U/kg enterokinase in the pancreatic duct. Three groups were studied (n = 5): control (C), pancreatitis (AP), and MB bolus followed by pancreatitis (MB+P). The data included serum and abdominal fluid enzymes, hemodynamic variables, arterial hemogasometry, abdominal fluid volume, inflammatory markers, plasma nitrite/nitrate (NOx), plasma myeloperoxidase (MPO) and plasma malondialdehyde (MDA). One- and two-way analysis of variance (ANOVA) was performed, followed by the Bonferroni test (p < 0.05).

RESULTS

amylase and lipase were three and 10-fold higher in the AP group. Myeloperoxidase activity was 50% higher in the AP group. The hemodynamic data indicated early hypovolemic shock followed by cardiogenic shock. Severe fluid translocation to the peritoneal cavity was observed. Plasma NOx remained unchanged. The MB+P group had a five-fold increase in MDA compared with the C group.

CONCLUSION

preemptive application of MB in pigs with AP demonstrated no significant effects on hemodynamic and inflammatory variables. The use of MB is inadequate in cases of exponential NO release, and extreme caution must be exercised, given the increase in lipid peroxidation based on the malondialdehyde dosage.

Sanguineous normothermic, intermittent cardioplegia, effects on hypertrophic myocardium. Morphometric, metabolic and ultrastructural studies in rabbits hearts

OBJECTIVES

The present investigation aimed to study the protective effect of intermittent normothermic cardioplegia in rabbit's hypertrophic hearts.

METHODS

The parameters chosen were 1) the ratio heart weight / body weight, 2) the myocardial glycogen levels, 3) ultrastructural changes of light and electron microscopy, and 4) mitochondrial respiration.

RESULTS

1) The experimental model, coarctation of the aorta induced left ventricular hypertrophy; 2) the temporal evolution of the glycogen levels in hypertrophic myocardium demonstrates that there is a significant decrease; 3) It was observed a time-dependent trend of higher oxygen consumption values in the hypertrophic group; 4) there was a significant time-dependent decrease in the respiratory coefficient rate in the hypertrophic group; 5) the stoichiometries values of the ADP: O2 revealed the downward trend of the values of the hypertrophic group; 6) It was possible to observe damaged mitochondria from hypertrophic myocardium emphasizing the large heterogeneity of data.

CONCLUSION

The acquisition of biochemical data, especially the increase in speed of glycogen breakdown, when anatomical changes are not detected, represents an important result even when considering all the difficulties inherent in the process of translating experimental results into clinical practice. With regard to the adopted methods, it is clear that morphometric methods are less specific. Otherwise, the biochemical data allow detecting alterations of glycogen concentrations and mitochondria respiration before the morphometric alterations should be detected.

The lignan (-)-cubebin inhibits vascular contraction and induces relaxation via nitric oxide activation in isolated rat aorta

Cubebin, the most abundant lignan in Piper cubeba, has been described as having several effects as trypanocidal, antimycobacterial, antispasmodic, antimicrobial, anti-inflammatory, and analgesic. This study investigated the vasorelaxant effect produced by (-)-cubebin in isolated rat aortic rings pre-contracted with phenylephrine (Phe), and the possible mechanism involved in this event was evaluated. Endothelium-dependent relaxation was evoked by acetylcholine and (-)-cubebin in intact aortic rings, while endothelium-independent vasorelaxation was elicited by sodium nitroprusside and (-)-cubebin in denuded rings. Cumulative concentration-response curves for Phe (10(-10) -10(-5)  M) were determined for endothelium-intact and endothelium-denuded aortic rings in either the presence or absence of (-)-cubebin. Dose-response curves were also constructed for pre-incubation of vascular rings with Nω-nitro-L-arginine methyl ester (L-NAME) (a non-specific nitric oxide synthase inhibitor), indomethacin (an unspecific cyclooxygenase inhibitor), and 1H-[1,2,4] oxadiazolo [4,3-a]quinoxalin-1-one (ODQ) (a guanylyl cyclase inhibitor). (-)-Cubebin was found to exert a vasorelaxant effect irrespective of the presence of endothelium, which was abolished by pretreatment with L-NAME and ODQ, but not with indomethacin. In addition, (-)-cubebin was able to reduce Phe contraction in the case of intact rings. These results suggest that (-)-cubebin promotes vasorelaxation via NO/cGMP pathway in rat aorta, without prostacyclin involvement.