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BACKGROUND: The Angiographic Microvascular Resistance (AMR), derived from a solitary angiographic view, has emerged as a viable substitute for the Index of Microcirculatory Resistance (IMR). However, the prognostic significance in ST-Segment Elevation Myocardial Infarction (STEMI) patients is yet to be established. This research endeavors to explore the prognostic capabilities of AMR in patients diagnosed with STEMI. METHODS: In this single-center, retrospective study, 232 patients diagnosed with STEMI who received primary Percutaneous Coronary Intervention (PCI) were recruited from January 1, 2018, to June 30, 2022. Utilizing the maximally selected log-rank statistics analysis, participants were divided into two cohorts according to an AMR threshold of 2.55 mmHg*s/cm. The endpoint evaluated was a composite of all-cause mortality or hospital readmission due to heart failure. RESULTS: At a median follow-up of 1.74 (1.07, 3.65) years, the composite endpoint event was observed in 28 patients within the higher AMR group and 8 patients within the lower AMR group. The higher AMR group showed a significantly higher risk for composite outcome compared to those within the low-AMR group (HRadj: 3.33; 95% CI 1.30‒8.52; p = 0.03). AMR ≥ 2.55 mmHg*s/cm was an independent predictor of the composite endpoint (HR = 2.33; 95% CI 1.04‒5.21; p = 0.04). Furthermore, a nomogram containing age, sex, left ventricle ejection fraction, post-PCI Quantitative Flow Ratio (QFR), and AMR was developed and indicated a poorer prognosis in the high-risk group for STEMI patients at 3 years. (HR=4.60; 95% CI 1.91‒11.07; p < 0.01). CONCLUSIONS: AMR measured after PCI can predict the risk of all-cause death or readmission for heart failure in patients with STEMI. AMR-involved nomograms improved predictive performance over variables alone.

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We sought to investigate possible impaired hyperaemia during dynamic handgrip exercise (HGE) in young healthy individuals who had recovered from COVID-19. We tested the vascular function in individuals recovered from COVID-19 using a nitric oxide donor (i.e., sodium nitroprusside; SNP), which could revert a possible impaired endothelial function during HGE. Further, we tested whether individuals who recovered from COVID-19 would present exaggerated brachial vascular resistance under an adrenergic agonist (i.e., phenylephrine; PHE) stimuli during HGE. Participants were distributed into two groups: healthy controls (Control; men: n = 6, 30 ± 3 years, 26 ± 1 kg/m2; and women: n = 5, 25 ± 1 years, 25 ± 1 kg/m2) and subjects recovered from COVID-19 (post-COVID; men: n = 6, 29 ± 3 years, 25 ± 1 kg/m2; and women: n = 10, 32 ± 4 years, 22 ± 1 kg/m2). Participants in the post-COVID group tested positive (RT-PCR) 12-14 weeks before the protocol. Heart rate (HR), brachial blood pressure (BP), brachial blood flow (BBF) and vascular conductance (BVC) at rest were not different between groups. The HGE increased HR (Control: Δ9 ± 0.4 bpm; and post-COVID: Δ11 ± 0.4 bpm) and BP (Control: Δ6 ± 1 mmHg; and post-COVID: Δ12 ± 0.6 mmHg) in both groups. Likewise, BBF (Control: Δ632 ± 38 ml/min; and post-COVID: Δ620 ± 27 ml/min) and BVC (Control: Δ6.6 ± 0.4 ml/min/mmHg; and post-COVID: Δ6.1 ± 0.3 ml/min/mmHg) increased during HGE. SNP did not change HGE-induced hyperaemia but did decrease BP, which induced a reflex-related increase in HR. PHE infusion also did not change the HGE-induced hyperaemia but raised BP and reduced HR. In conclusion, exercise-induced hyperaemia is preserved in healthy young subjects 12-14 weeks after recovery from COVID-19 infection.

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It is of paramount importance to characterize the individual hemodynamic response of patients with postural orthostatic tachycardia syndrome (POTS) to select the best therapeutic intervention. Our aim in this study was to describe the hemodynamic changes in 40 patients with POTS during the head-up tilt test and compare them with 48 healthy patients. Hemodynamic parameters were obtained by cardiac bioimpedance. Patients were compared in supine position and after 5, 10, 15, and 20 minutes of orthostatic position. Patients with POTS demonstrated higher heart rate (74 beats per minute [64 to 80] vs 67 [62 to 72], p <0.001) and lower stroke volume (SV) (83.0 ml [72 to 94] vs 90 [79 to 112], p <0.001) at supine position. The response to orthostatic challenge was characterized by a decrease in SV index (SVI) in both groups (ΔSVI in ml/m2: -16 [-25 to -7.] vs -11 [-17 to -6.1], p = NS). Peripheral vascular resistance (PVR) was reduced only in POTS (ΔPVR in dyne.seg/cm5:-52 [-279 to 163] vs 326 [58 to 535], p <0.001). According to the best cut-off points obtained using the receiver operating characteristic analysis for the variation of SVI (-15.5%) and PVR index (PVRI) (-5.5%), we observed 4 distinct groups of POTS: 10% presented an increase in both SVI and PVRI after the orthostatic challenge, 35% presented a PVRI decrease with SVI maintenance or increase, 37.5% presented an SVI decrease with PVRI maintenance or elevation, and 17.5% presented a reduction in both variables. Body mass index, ΔSVI, and ΔPVRI were strongly correlated with POTS (area under the curve = 0.86 [95% confidence interval 0.77 to 0.92], p <0.0001). In conclusion, the use of appropriate cut-off points for hemodynamic parameters using bioimpedance cardiography during the head-up tilt test could be a useful strategy to identify the main mechanism involved and to select the best individual therapeutic strategy in POTS.

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La adaptación fisiológica de los recién nacidos de la vida intrauterina a la extrauterina incluye cambios fisiológicos complejos. Para que se complete con éxito la transición fetal a neonatal, los recién nacidos deben lograr el aclaramiento de líquido pulmonar, la generación de CRF e inicio de la respiración, para permitir el intercambio de gases y la oxigenación de los tejidos. En este artículo se describen estos mecanismos, algunas bases del desarrollo pulmonar y de la circulación fetal; y las medidas que se requieren para asistir al recién nacido cuando no logran completar esta transición espontáneamente, lo que ocurre en el 5 al 10 % de los casos.

The physiological adaptation of newborns from intrauterine to extrauterine life includes complex physiological changes. For the fetal to neonatal transition to be successfully completed, neonates must achieve lung fluid clearance, FRC generation, and initiation of respiration to allow gas exchange and tissue oxygenation. This article describes these mechanisms, some bases of lung development and fetal circulation; and the measures required to assist the newborn, when they fail to complete this transition spontaneously, which occurs in the 5 to 10% of cases.

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INTRODUCTION: Pulmonary artery denervation (PADN) can reduce the sympathetic nervous system (SNS) activity, reduce pulmonary artery pressure (PAP), and improve the quality of life in patients with pulmonary hypertension (PH). We conducted a systematic meta-analysis of the effectiveness of PADN in the treatment of PH patients. METHODS: This is a comprehensive literature search including all public clinical trials investigating the effects of PADN on PH. Outcomes were mean pulmonary artery pressure (mPAP), pulmonary vascular resistance (PVR), cardiac output (CO), right ventricular (RV) Tei index, 6-minute walk distance (6MWD), and New York Heart Association (NYHA) cardiac function grading. RESULTS: A total of eight clinical studies with 213 PH patients who underwent PADN were included. Meta-analysis showed that after PADN, mPAP (mean difference [] -12.51, 95% confidence interval [CI] -17.74 to -7.27, P<0.00001) (mmHg) and PVR ( -5.17, 95% CI -7.70 to -2.65, P<0.0001) (Wood unit) decreased significantly, CO ( 0.59, 95% CI 0.32 to 0.86, P<0.0001) (L/min) and 6MWD ( 107.75, 95% CI 65.64 to 149.86, P<0.00001) (meter) increased significantly, and RV Tei index ( -0.05, 95% CI -0.28 to 0.17, P=0.63) did not change significantly. Also after PADN, the proportion of NYHA cardiac function grading (risk ratio 0.23, 95% CI 0.14 to 0.37, P<0.00001) III and IV decreased significantly. CONCLUSION: This meta-analysis supports PADN as a potential new treatment for PH. Further high-quality randomized controlled studies are needed.

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Several limitations regarding pulse pressure variation (PPV) use have been reported. Our aim was to describe changes in the PPV operative performance as a predictor of fluid responsiveness during the development of a swine endotoxin shock model and to assess hemodynamic variables associated with PPV changes. A swine porcine endotoxin shock model was established (Escherichia Coli 055:B5 endotoxin) in 7 pigs, and 3 pigs were included in the control group. The endotoxin was infused until the mean arterial pressure (MAP) dropped below 50 mmHg (TH0); then, the model animal was reanimated with fluids and vasopressors. We performed fluid challenges every hour for 6 h. ROC curve analysis and a linear mixed model were performed. The area under the curve of PPV decreased from 0.95 (0.81-1.00) to 0.60 (0.17-1.00) at TH0. Its cutoff increased from 10.5 to 22.00% at TH0. PPV showed an inverse relationship with stroke volume, mean systemic filling pressure, MAP, and systemic vascular resistance (SVR) (p < 0.001, AIC = 111.85). The PPV operative performance as a predictor of fluid responsiveness decreased with the progression of shock. This could lead to an inverse association between PPV and the following variables: MAP and SVR.

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There is a consensus that arterial hypertension (AH) is associated with stroke. Therefore, this study aimed to evaluate the histology of the microvasculature associated with the mucosa of the posterior nasal cavity to identify possible factors related to vascular weakening and rupture. Histological sections were obtained from hypertensive and normotensive individuals, regardless of epistaxis. Our results showed that the group with AH had: (a) smaller median diameter of the lumen of arteries and arterioles; (b) increased thickness of the intimal arteries and arterioles, slight inflammatory infiltrate, and rupture of internal elastic lamina; (c) greater thickness of the middle tunica in arterioles; (d) lower percentage of histological sections with non-injured intimal layers in capillaries, arterioles, and small arteries; (e) lower percentage of histological sections with intact media tunic and/or myocytes juxtaposed in arteries and arterioles; (f) no difference between the diameters of small arteries or arterioles. The intima was thicker in individuals with severe epistaxis than in the normotensive group, but it did not differ from the AH group. Thus, hypertension may cause structural lesions in the vascular layers, and in the absence of tissue repair and the persistence of AH, these lesions may favour vascular rupture, especially during hypertensive peaks.

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Introdução: A hipertensão arterial sistêmica (HAS) pode levar a consequências cardiovasculares graves quando não tratadas adequadamente. No entanto, alguns indivíduos, mesmo realizando tratamento recomendado, a pressão arterial (PA) se mantém elevada, passando a ser chamada de hipertensão arterial refratária (HAR). A denervação simpática renal (DSR) é uma terapia amplamente estuda e com resultados promissores que surgiu como alternativa para controlar a PA em pacientes resistentes ao tratamento convencional. Relato de caso: Participante da pesquisa, sexo masculino, 67 anos, com queixa de cefaleia e elevação dos níveis pressóricos. Avaliação cardíaca com alteração apenas da PA (182x113 mmHg), demais sistemas sem variações. Diagnosticado com HAS estágio 3, realizou todas as etapas do tratamento medicamentoso, porém resistente as terapias propostas. Diante do caso, foi diagnosticado com HAR. Sendo realizado DSR que mostrou resultados satisfatórios de redução progressiva da pressão arterial central e periférica. Conclusão: A DSR mostrou-se eficaz no controle gradual e sustentado da PA do participante da pesquisa. Contudo, somente através de estudos clínicos mais amplos e rigorosos será capaz de comprovar a eficácia da DSR no tratamento da PA alta persistente (AU).

Introduction: Systemic arterial hypertension (SHT) can lead to severe cardiovascular outcomes when not properly treated. However, in some individuals, even with recommended treatment, blood pressure (BP) remains high, and is now referred to as Resistant hypertension (RHTN). Renal sympathetic denervation (RDn) is a widely studied and promising therapy that has emerged as an alternative to control BP in patients resistant to conventional treatment. Case report: Research participant, male, 67 years old, complaining of headache and elevated blood pressure. Cardiac assessment with only BP alteration (182x113 mmHg), other systems without variations. Diagnosed with stage 3 hypertension, performed all stages of drug treatment, but resistant to the proposed therapies. Given the case, was diagnosed with RHTN. Being performed RDn that showed satisfactory results of progressive reduction of central and peripheral blood pressure. Discussion: Sympathetic hyperactivity of the renal nervous system releases catecholamines that raise BP. Based on this, the RDn uses a catheter connected to the radiofrequency device that through the femoral artery goes to the two renal arteries and emits energy in the sympathetic fibers attached to the walls of these arteries, destroying them. RDn has been the target of several clinical studies, the best-known being Simplicity HTN-1, 2 and 3 which brought significant and questionable results regarding the efficacy of the procedure. Conclusion: RDn proved to be effective in gradually and sustained BP control of the research participant. However, only through broader and more rigorous clinical studies will it be able to prove the efficacy of RDn in combating persistent high BP (AU).

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El pulmón recibe sangre desde la circulación bronquial y pulmonar. La circulación pulmonar presenta importantes diferencias con la sistémica, sus vasos sanguíneos poseen características únicas que le permiten cumplir sus diferentes funciones, siendo la más importante el intercambio gaseoso. Existen múltiples factores, activos y pasivos, que están involucrados en la regulación de la resistencia vascular y flujo sanguíneo pulmonar.

The lung receives blood from the bronchial and the pulmonary circulation. The pulmonary circulation presents important differences with the systemic circulation, its blood vessels have unique characteristics that allow them to fulfill their different functions, the most important being gas exchange. There are multiple factors, active and passive, that are involved in the regulation of vascular resistance and pulmonary blood flow.

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