Fisiología respiratoria: circulación pulmonar / Respiratory physiology: pulmonary circulation

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.

Prevalencia de disfunción diastólica de acuerdo con las guías diagnósticas de 2009 y 2016. Relación con la valoración hemodinámica no invasiva / Prevalence of diastolic dysfunction (DD) according to the diagnostic guidelines of 2009 and 2016. Relationship with non-invasive hemodynamic assessment

Resumen Objetivos: Evaluar la prevalencia de DD de acuerdo con los criterios de las guías del 2009 y 2016, y su relación con la distensibilidad arterial sistémica (DAS) y la resistencia vascular periférica (RVP). Material y métodos: Se analizó a 306 pacientes ≥ 40 años de edad, con fracción de expulsión ≥ 50%. Se calcularon en todos DAS y RVP. Resultados: La prevalencia de DD fue de 32.7% y 22.9% según las guías de 2009 y 2016, respectivamente (p = < 0.0001). De acuerdo con las guías del 2009, los pacientes con DD presentaron una media de DAS menor que aquéllos con función normal (p = 0.0001), de modo similar a las guías del 2016 (p = 0.0007). La DD, según las guías de 2009 y 2016, mostró valores más altos de RVP que los normales (p = 0.005 y p = 0.018, respectivamente). Asimismo, la DD fue predictora, en el análisis univariado, de DAS < 0.60 ml.mm Hg-1 y RVP > 1,400 mmHg.min.l-1 según ambas guías. En el análisis multivariado, la DD, de acuerdo con las guías del 2009, persistió como predictor independiente de RVP > 1,400 mmHg.min.l-1. Conclusión: Las guías del 2016 reducen la prevalencia de DD. Ésta, tanto en las guías del 2009 como en las del 2106, fue predictor univariado de DAS < 0.60 ml.mmHg-1 y RVP > 1,400 mmHg.min.l-1. La DD, de acuerdo con las guías de 2009, resultó predictora independiente de RVP > 1,400 mmHg.min.l-1.

Abstract Objectives: To assess the prevalence of developmental disabilities (DD) according to the criteria of the 2009 and 2016 guidelines, and its association with systemic arterial compliance (DAS) and peripheral vascular resistance (RVP). Material and methods: 306 patients aged ≥ 40 years, with ejection fraction ≥ 50% were analyzed. It was estimated in all DAS and RVP. Results: The prevalence of DD was 32.7% and 22.9% according to the 2009 and 2016 guidelines, respectively (p ≤ 0.0001). Patients with DD according to the 2009 guideline had a lower average of DAS than those with normal function (p = 0.0001). Similar with the 2016 guide (p = 0.0007). The presence of DD according to the 2009 and 2016 guideline showed higher RVP values than normal values (p = 0.005 and p = 0.018, respectively). The DD according to both guidelines was a predictor, in the univariate analysis, of DAS < 0.60 ml.mmHg−1 and RVP > 1400 mmHg.min.l−1. The DD according to the 2009 guideline persisted as an independent predictor, in the multivariate analysis, of RVP > 1400 mmHg.min.l−1. Conclusion: The 2016 guide decreases the prevalence of DD. The DD, both from the 2009 and 2106 guidelines, were univariate predictors of DAS <0.60 ml.mmHg−1 and RVP > 1400 mmHg.min.l−1. The DD according to the 2009 guide, was an independent predictor of RVP > 1400 mmHg.min.l−1.

Anxiety increases the blood pressure response during exercise

Aim: The hypothesis that higher levels of anxiety promote greater blood pressure (BP) responses during physical exercise is tested. The hypothesis that metaborreflex response is increased in an anxious individual is tested as well. Methods: There were 43 volunteers divided by anxiety level: 12 volunteers with mild, moderate and severe symptoms (anxious-group) and 31 volunteers with a minimum level of anxiety (control-group). Arterial BP, heart rate, and forearm blood flow were measured simultaneously during handgrip exercise and post-exercise ischemia, and forearm vascular resistance (FVR) was calculated. Results: Anxious group present higher systolic, diastolic and mean BP at rest when compared with control group (130±11 vs. 122±12 mmHg, p=0.048; 70±6 vs. 65±8 mmHg, p=0.033; 90±7 vs. 84±9 mmHg, p=0.033, respectively) and higher response of systolic, diastolic and mean BP and FVR during exercise when compared with control group (20±9 vs. 13±7 mmHg, p=0.009; 17±8 vs. 11±6 mmHg, p=0.006; 18±8 vs. 11±6 mmHg, p=0.005; and 0±13 vs. -7±9 units, p=0,003, respectively). During post-exercise ischemia, the anxious group also present higher response of diastolic BP, mean BP and FVR when compared with a control group (11±12 vs. 3±4 mmHg, p=0,001, 10±8 vs. 3±5 mmHg, p=0,002; 9±11 vs. -2± 8 units, p=0,03, respectively). Conclusion: Anxious individuals present higher BP responses during physical exercise when compared with those with minimal anxiety symptoms. This increased response may be explained, in part, by increased peripheral vascular resistance due to the greater metaborreflex response.(AU)

Uso de ecocardiografia junto ao leito para medir índices cardíaco e de resistência vascular sistêmica em pacientes pediátricos com choque séptico / The use of bedside echocardiography for measuring cardiac index and systemic vascular resistance in pediatric patients with septic shock

RESUMO Objetivo: Acompanhar o índice cardíaco e o índice de resistência vascular sistêmica até a ressuscitação. Métodos: Por meio de ecocardiografia junto ao leito, obteve-se um conjunto de parâmetros hemodinâmicos, inclusive débito cardíaco, volume sistólico, índice cardíaco, índice de resistência vascular sistêmica, integral velocidade-tempo, índice de desempenho miocárdico, tempo de reenchimento capilar e frequência cardíaca no momento zero após infusão de fluidos em bolo, e início e utilização de fármacos inotrópicos, com seguimento até 6 horas e 24 horas. Resultados: Incluíram-se 45 pacientes com choque séptico adquirido na comunidade. Os focos de infecção foram gastrenterite (24%), perfuração intestinal com necessidade de cirurgia emergencial (24%), pneumonia (20%), infecção do sistema nervoso central (22%) e infecção de tecidos moles (8%). Os isolados mais frequentes foram de Klebsiella e Enterobacter. Estimamos os fatores que afetaram o índice cardíaco: pressão venosa central elevada no momento zero (r = 0,33; p = 0,024) e persistência de frequência cardíaca elevada após 6 horas (r = 0,33; p = 0,03). O índice de resistência vascular sistêmica foi alto na maioria dos pacientes no momento zero e após 24 horas, e por ocasião da ressuscitação, afetando inversamente o índice cardíaco, assim como a integral velocidade-tempo (r = -0,416; -0,61; 0,55 e -0,295). O tempo de reenchimento capilar aumentado foi preditor clínico de valores baixos de integral velocidade-tempo após 24 horas (r = -0,4). O índice de mortalidade foi de 27%. Nos pacientes que não sobreviveram, observaram-se índices de resistência vascular sistêmica mais baixos e débitos cardíacos mais altos. Conclusão: O índice de resistência vascular sistêmica esteve persistentemente elevado em pacientes com choque frio, o que influenciou no índice de volume sistólico, no índice cardíaco e na integral velocidade-tempo. O uso de ecocardiografia para obtenção de mensurações hemodinâmicas é importante em pacientes pediátricos com choque séptico, para que se possam ajustar as doses de vasodilatadores e vasopressores, e obter os objetivos da ressuscitação em tempo apropriado.

ABSTRACT Objective: Follow-up of cardiac index and systemic vascular resistance index by bedside echocardiography until resuscitation. Methods: A set of hemodynamic parameters was obtained, including cardiac output, stroke volume, cardiac index, systemic vascular resistance index, velocity time integral, myocardial performance index, capillary refill time, and heart rate at 0 hours after fluid boluses before the start of inotropes, and followed up after 6 hours and 24 hours. Results: Included were 45 patients with community-acquired septic shock. Septic foci were gastroenteritis (24%), intestinal perforation requiring emergency surgery (24%), pneumonia (20%), central nervous system infection (22%) and soft tissue infection (8%). Klebsiella and Enterobacter were the most frequent isolates. We estimated the factors affecting the cardiac index: high central venous pressure at zero time (r = 0.33, p = 0.024) and persistently high heart rate at hour 6 (r = 0.33, p = 0.03). The systemic vascular resistance index was high in most patients at 0 and 24 hours and at the time of resuscitation and inversely affected the cardiac index as well as affecting the velocity time integral (r = -0.416, -0.61, 0.55 and -0.295). Prolonged capillary refill time was a clinical predictor of the low velocity time integral at 24 hours (r = -0.4). The mortality was 27%. Lower systemic vascular resistance index and higher cardiac output were observed in nonsurviving patients. Conclusion: There was a persistently high systemic vascular resistance index in cold shock patients that influenced the stroke volume index, cardiac index, and velocity time integral. The use of echocardiograms for hemodynamic measurements is important in pediatric septic shock patients to adjust dilators, and vasopressor doses and achieve resuscitation targets in a timely manner.

Comparison of Cardiac and Vascular Parameters in Powerlifters and Long-Distance Runners: Comparative Cross-Sectional Study / Comparação de Parâmetros Cardíacos e Vasculares em Powerlifters e Corredores de Longa Distância: Um Estudo Transversal Comparativo

Abstract Background: Cardiac remodeling is a specific response to exercise training and time exposure. We hypothesized that athletes engaging for long periods in high-intensity strength training show heart and/or vascular damage. Objective: To compare cardiac characteristics (structure and function) and vascular function (flow-mediated dilation [FMD] and peripheral vascular resistance [PVR]) in powerlifters and long-distance runners. Methods: We evaluated 40 high-performance athletes (powerlifters [PG], n = 16; runners [RG], n = 24) and assessed heart structure and function (echocardiography), systolic and diastolic blood pressure (SBP/DBP), FMD, PVR, maximum force (squat, bench press, and deadlift), and maximal oxygen uptake (spirometry). A Student's t Test for independent samples and Pearson's linear correlation were used (p < 0.05). Results: PG showed higher SBP/DBP (p < 0.001); greater interventricular septum thickness (p < 0.001), posterior wall thickness (p < 0.001) and LV mass (p < 0.001). After adjusting LV mass by body surface area (BSA), no difference was observed. As for diastolic function, LV diastolic volume, wave E, wave e', and E/e' ratio were similar for both groups. However, LA volume (p = 0.016) and BSA-adjusted LA volume were lower in PG (p < 0.001). Systolic function (end-systolic volume and ejection fraction), and FMD were similar in both groups. However, higher PVR in PG was observed (p = 0.014). We found a correlation between the main cardiovascular changes and total weight lifted in PG. Conclusions: Cardiovascular adaptations are dependent on training modality and the borderline structural cardiac changes are not accompanied by impaired function in powerlifters. However, a mild increase in blood pressure seems to be related to PVR rather than endothelial function.

Resumo Fundamento: Remodelamento cardíaco é uma resposta específica ao tempo e modalidade de treinamento. Nós hipotetizamos que atletas de treinamento de força de alta intensidade, por longo tempo, mostram dano à estrutura cardíaca e/ou vascular. Objetivo: Comparar as características cardíacas (estrutura e funcionalidade) e função vascular (dilatação fluxo-mediada, FMD e resistência vascular periférica, PVR) em powerlifters e corredores. Métodos: Nós avaliamos 40 atletas de alto-desempenho (powerlifters [PG], n = 16; corredores [RG], n = 24). Mensuramos estrutura e funcionalidade cardíaca (ecocardiografia), pressão arterial (SBP/DBP), FMD, PVR, força máxima (agachamento, supino e levantamento terra) e consumo máximo de oxigênio (ergoespirometria). Foi utilizado teste T de Student e correlação linear de Pearson (p < 0,05). Resultados: PG mostrou maior SBP/DBP (p < 0,001), espessura de septo interventricular (p < 0,001), parede posterior (p < 0,001) e massa do VE (p < 0,001); após ajuste pela superfície corporal (BSA), não houve diferença na massa do VE. O volume do VE, onda E, onda e', e a razão E/e' foram similares entre os grupos. O volume do AE (p = 0,016), mesmo ajustado pela BSA (p < 0,001) foi menor no PG. A função sistólica (volume sistólico final e fração de ejeção) e FMD foram similares nos grupos. Contudo, foi observada maior PVR no PG (p = 0,014). Houve uma correlação direta entre as alterações cardíacas e a carga total levantada no PG. Conclusões: As adaptações cardiovasculares são dependentes da modalidade e os valores encontrados na estrutura do coração não são acompanhados por prejuízo na funcionalidade. Entretanto, um leve aumento na pressão arterial pode estar associado com maior PVR e não com a função endotelial.

Lidocaine and pinacidil added to blood versus crystalloid cardioplegic solutions: study in isolated hearts

Abstract Objective: The present study aimed the functional recovery evaluation after long term of cardiac arrest induced by Custodiol (crystalloid-based) versus del Nido (blood-based) solutions, both added lidocaine and pinacidil as cardioplegic agents. Experiments were performed in isolated rat heart perfusion models. Methods: Male rat heart perfusions, according to Langendorff technique, were induced to cause 3 hours of cardiac arrest with a single dose. The hearts were assigned to one of the following three groups: (I) control; (II) Custodiol-LP; and (III) del Nido-LP. They were evaluated after ischemia throughout 90 minutes of reperfusion. Left ventricular contractility function was reported as percentage of recovery, expressed by developed pressure, maximum dP/dt, minimum dP/dt, and rate pressure product variables. In addition, coronary resistance and myocardial injury marker by alpha-fodrin degradation were also evaluated. Results: At 90 minutes of reperfusion, both solutions had superior left ventricular contractile recovery function than the control group. Del Nido-LP was superior to Custodiol-LP in maximum dP/dt (46%±8 vs. 67%±7, P<0.05) and minimum dP/dt (31%±4 vs. 51%±9, P<0.05) variables. Coronary resistance was lower in del Nido-LP group than in Custodiol-LP (395%±50 vs. 307%±13, P<0.05), as well as alpha-fodrin degradation, with lower levels in del Nido-LP group (P<0.05). Conclusion: Del Nido-LP cardioplegia showed higher functional recovery after 3 hours of ischemia. The analysis of alpha-fodrin degradation showed del Nido-LP solution provided greater protection against myocardial ischemia and reperfusion (IR) in this experimental model.

Exercise Training Attenuates Sympathetic Activity and Improves Morphometry of Splenic Arterioles in Spontaneously Hipertensive Rats / Treinamento Físico Atenua a Atividade Simpática e Melhora a Morfometria das Arteríolas Esplênicas em Ratos Espontaneamente Hipertensos

Abstract Background: Alterations in the structure of resistance vessels contribute to elevated systemic vascular resistance in hypertension and are linked to sympathetic hyperactivity and related lesions in target organs. Objective: To assess the effects of exercise training on hemodynamic and autonomic parameters, as well as splenic arteriolar damages in male Wistar Kyoto (WKY) and Spontaneously Hypertensive Rats (SHR). Methods: Normotensive sedentary (WKYS) and trained (WKYT) rats, and hypertensive sedentary (SHRS) and trained (SHRT) rats were included in this study. After 9 weeks of experimental protocol (swimming training or sedentary control), arterial pressure (AP) and heart rate (HR) were recorded in freely moving rats. We assessed the autonomic control of the heart by sympathetic and vagal autonomic blockade. Morphometric analyses of arterioles were performed in spleen tissues. The statistical significance level was set at p < 0.05. Results: Resting bradycardia was observed in both trained groups (WKYT: 328.0 ± 7.3 bpm; SHRT: 337.0 ± 5.2 bpm) compared with their respective sedentary groups (WKYS: 353.2 ± 8.5 bpm; SHRS: 412.1 ± 10.4 bpm; p < 0.001). Exercise training attenuated mean AP only in SHRT (125.9 ± 6.2 mmHg) vs. SHRS (182.5 ± 4.2 mmHg, p < 0.001). The WKYT showed a higher vagal effect (∆HR: 79.0 ± 2.3 bpm) compared with WKYS (∆HR: 67.4 ± 1.7 bpm; p < 0.05). Chronic exercise decreased sympathetic effects on SHRT (∆HR: -62.8 ± 2.8 bpm) in comparison with SHRS (∆HR: -99.8 ± 9.2 bpm; p = 0.005). The wall thickness of splenic arterioles in SHR was reduced by training (332.1 ± 16.0 µm2 in SHRT vs. 502.7 ± 36.3 µm2 in SHRS; p < 0.05). Conclusions: Exercise training attenuates sympathetic activity and AP in SHR, which may be contributing to the morphological improvement of the splenic arterioles.

Resumo Fundamento: Alterações na estrutura dos vasos de resistência contribuem para elevar a resistência vascular sistêmica na hipertensão, estando ligadas à hiperatividade simpática e lesões em órgãos-alvo. Objetivo: Avaliar os efeitos do treinamento físico nos parâmetros hemodinâmicos e autônomos, assim como as lesões arteriolares esplênica em ratos machos Wistar Kyoto (WKY) e espontaneamente hipertensos (SHR). Métodos: Ratos normotensos sedentários (WKYS) e treinados (WKYT), e ratos hipertensos sedentários (SHRS) e treinados (SHRT) foram incluídos neste estudo. Após nove semanas de aplicação do protocolo experimental (treinamento de natação ou controle sedentário), registraram-se a pressão arterial (PA) e a frequência cardíaca (FC) dos ratos em movimento livre. Avaliamos o controle autônomo do coração através de bloqueio autônomo simpático e vagal. Análises morfométricas das arteríolas esplênicas foram realizadas. Adotou-se o nível de significado estatístico de p < 0,05. Resultados: Observou-se bradicardia de repouso nos dois grupos treinados (WKYT: 328,0 ± 7,3 bpm; SHRT: 337,0 ± 5,2 bpm) em comparação aos seus respectivos grupos sedentários (WKYS: 353,2 ± 8,5 bpm; SHRS: 412,1 ± 10,4 bpm; p < 0,001). O treinamento físico atenuou a PA média apenas no grupo SHRT (125,9 ± 6,2 mmHg vs. 182,5 ± 4,2 mmHg no SHRS; p < 0,001). O grupo WKYT mostrou maior efeito vagal (∆FC: 79,0 ± 2,3 bpm) em comparação ao grupo WKYS (∆FC: 67,4 ± 1,7 bpm; p < 0,05). Exercício crônico diminuiu os efeitos simpáticos em SHRT (∆FC: -62.8 ± 2.8 bpm) em comparação a SHRS (∆FC: -99,8 ± 9,2 bpm; p = 0,005). A espessura da parede das arteríolas esplênicas nos SHR foi reduzida pelo treinamento (332,1 ± 16,0 µm2 nos SHRT vs. 502,7 ± 36,3 µm2 nos SHRS; p < 0,05). Conclusões: O treinamento físico atenua a atividade simpática e a PA em SHR, o que pode contribuir para melhorar a morfologia das arteríolas esplênicas.

Autonomic and Vascular Control in Prehypertensive Subjects with a Family History of Arterial Hypertension / Controle Autonômico e Vascular em Pré-Hipertensos com Histórico Familiar de Hipertensão Arterial

Abstract Background: Individuals with a family history of systemic arterial hypertension (FHSAH) and / or prehypertension have a higher risk of developing this pathology. Objective: To evaluate the autonomic and vascular functions of prehypertensive patients with FHSAH. Methods: Twenty-five young volunteers with FHSAH, 14 normotensive and 11 prehypertensive subjects were submitted to vascular function evaluation by forearm vascular conductance(VC) during resting and reactive hyperemia (Hokanson®) and cardiac and peripheral autonomic modulation, quantified, respectively, by spectral analysis of heart rate (ECG) and systolic blood pressure (SBP) (FinometerPRO®). The transfer function analysis was used to measure the gain and response time of baroreflex. The statistical significance adopted was p ≤ 0.05. Results: Pre-hypertensive individuals, in relation to normotensive individuals, have higher VC both at rest (3.48 ± 1.26 vs. 2.67 ± 0.72 units, p = 0.05) and peak reactive hyperemia (25, 02 ± 8.18 vs. 18.66 ± 6.07 units, p = 0.04). The indices of cardiac autonomic modulation were similar between the groups. However, in the peripheral autonomic modulation, greater variability was observed in prehypertensive patients compared to normotensive individuals (9.4 [4.9-12.7] vs. 18.3 [14.8-26.7] mmHg2; p < 0.01) and higher spectral components of very low (6.9 [2.0-11.1] vs. 13.5 [10.7-22.4] mmHg2, p = 0.01) and low frequencies (1.7 [1.0-3.0] vs. 3.0 [2.0-4.0] mmHg2, p = 0.04) of SBP. Additionally, we observed a lower gain of baroreflex control in prehypertensive patients compared to normotensive patients (12.16 ± 4.18 vs. 18.23 ± 7.11 ms/mmHg, p = 0.03), but similar delay time (-1.55 ± 0.66 vs. -1.58 ± 0.72 s, p = 0.90). Conclusion: Prehypertensive patients with FHSAH have autonomic dysfunction and increased vascular conductance when compared to normotensive patients with the same risk factor.

Resumo Fundamento: Indivíduos com histórico familiar de hipertensão arterial sistêmica (HFHAS) e/ou pré-hipertensão apresentam maior risco de desenvolver essa patologia. Objetivo: Avaliar as funções autonômica e vascular de pré-hipertensos com HFHAS. Métodos: Vinte e cinco voluntários jovens com HFHAS, sendo 14 normotensos e 11 pré-hipertensos foram submetidos à avaliação da função vascular, por meio da condutância vascular do antebraço (CV) durante repouso e hiperemia reativa (Hokanson®), e da modulação autonômica cardíaca e periférica, quantificada, respectivamente, por meio da análise espectral da frequência cardíaca (ECG) e da pressão arterial sistólica (PAS) (FinometerPRO®). A análise da função de transferência foi utilizada para mensurar o ganho e o tempo de resposta do barorreflexo. A significância estatística adotada foi p ≤ 0,05. Resultados: Pré-hipertensos, em relação aos normotensos, tem maior CV tanto em repouso (3,48 ± 1,26 vs. 2,67 ± 0,72 unidades; p = 0,05) quanto no pico hiperemia reativa (25,02 ± 8,18 vs. 18,66 ± 6,07 unidades; p = 0,04). Os índices da modulação autonômica cardíaca foram semelhantes entre os grupos. Entretanto, na modulação autonômica periférica, foi observado, nos pré-hipertensos em relação aos normotensos, maior variabilidade (9,4 [4,9-12,7] vs. 18,3 [14,8-26,7] mmHg2; p < 0,01) e maiores componentes espectrais de muito baixa (6,9 [2,0-11,1] vs. 13,5 [10,7-22,4] mmHg2; p = 0,01) e baixa frequências (1,7 [1,0-3,0] vs. 3,0 [2,0-4,0] mmHg2; p = 0,04) da PAS. Adicionalmente, observamos menor ganho do controle barorreflexo nos pré-hipertensos em relação aos normotensos (12,16 ± 4,18 vs. 18,23 ± 7,11 ms/mmHg; p = 0,03), porém, tempo de retardo semelhante (-1,55 ± 0,66 vs. -1,58 ± 0.72 s; p = 0,90). Conclusão: Pré-hipertensos com HFHAS tem disfunção autonômica e condutância vascular aumentada quando comparados a normotensos com o mesmo fator de risco.

Association of Inflammation and Endothelial Dysfunction with Coronary Microvascular Resistance in Patients with Cardiac Syndrome X / Associação de Inflamação e Disfunção Endotelial com Resistência Microvascular Coronariana em Pacientes com Síndrome Cardíaca X

Abstract Background: Although a proportion of CSX patients have impaired brachial artery flow-mediated dilatation (FMD) in response to hyperemia, suggesting that endothelial dysfunction in these patients may be systemic and not just confined to the coronary circulation; the underlying mechanisms triggering endothelial dysfunction in these patients are still incompletely understood. Objectives: To assess the association of the index of Microcirculatory Resistance (IMR) with endothelial dysfunction and inflammation in patients with CSX. Methods: We studied 20 CSX patients and 20 age and gender-matched control subjects. Thermodilution-derived coronary flow reserve (CFR) and IMR were measured using a pressure-temperature sensor-tipped guidewire. Brachial artery FMD was measured using high-resolution, two-dimensional ultrasound images obtained with a Doppler ultrasound device (HDI-ATL 5000, USA) with a 5 MHz to 12 MHz linear-array transducer. Results: Compared with in control subjects, CFR was significantly lower (2.42 ± 0.78 vs. 3.59 ± 0.79, p < 0.001); IMR was higher (32.2 ± 8.0 vs. 19.5 ± 5.5, p < 0.001); the concentration of hs-CRP and FMD was higher (4.75 ± 1.62 vs. 2.75 ± 1.50; 5.24 ± 2.41 vs. 8.57 ± 2.46, p < 0.001) in CSX patients. The Duke treadmill score (DTS) was correlated positively to CFR and FMD (0.489 and 0.661, p < 0.001), it was negative to IMR and hsCRP (-0.761 and -0.087, p < 0.001) in CSX patients. Conclusions: The main finding in this study is that the DTS measured in patients with CSX was associated to hsCRP and FMD. Moreover, the independent effects of exercise tolerance can significantly impair FMD and hsCRP in CSX patients; especially it is particularly important to whom where FMD was associated negatively with IMR.

Resumo Fundamentos: Embora uma proporção de pacientes com SCX tenha dilatação mediada por fluxo da artéria braquial (DMF) prejudicada em resposta à hiperemia, sugerindo que a disfunção endotelial nestes pacientes pode ser sistémica e não limitar-se à circulação coronariana, os mecanismos subjacentes que desencadeiam a disfunção endotelial nestes pacientes ainda não são completamente compreendidos. Objetivos: Avaliar a associação do índice de resistência microcirculatória (IMR) com a disfunção endotelial e a inflamação em pacientes com SCX. Métodos: Estudaram-se 20 pacientes com SCX e 20 sujeitos de controle emparelhados em idade e género. A reserva de fluxo coronariano derivada da termodiluição (RFC) e a IMR forma medidas usando um fio guia com ponta de sensor de temperatura e pressão. A DMF da artéria braquial foi medida utilizando imagens ultrassónicas bidimensionais de alta resolução obtidas com um aparelho de ultrassom Doppler (HDI-ATL 5000, EE.UU.) com transdutor linear de 5 MHz a 12 MHz. Resultados: Em comparação com os sujeitos de controle, a RFC foi significativamente menor (2,42 ± 0,78 vs 3,59 ± 0,79, p < 0,001); o IMR foi maior (32,2 ± 8,0 frente a 19,5 ± 5,5, p < 0,001); a concentração de PCR-as e DMF foi maior (4,75 ± 1,62 frente a 2,75 ± 1,50, 5,24 ± 2,41 diante de 8,57 ± 2,46, p < 0,001) em pacientes com SCX. A escore de Duke (ED) se correlacionou positivamente com RFC e DMF (0,489 e 0,661, p < 0,001), foi negativa para IMR e PCR-as (-0,761 e -0,087, p < 0,001) em pacientes com SCX. Conclusões: O principal achado neste estudo é que o ED medido em pacientes com SCX esteve associado a PCR-as e DMF. Por outra parte, os efeitos independentes da tolerância ao exercício podem piorar significativamente a DMF e a PCR-as em pacientes com SCX especialmente, é particularmente importante que a DMF se associou negativamente com a RIM.

Antiretroviral therapy and arterial elasticity in HIV-infected patients

Cardiovascular risk is increased in HIV-infected patients and has become a leading cause of morbimortality in this population. The purpose of this study is to compare HIV-infected patients on antiretroviral therapy (ART) and ART-naïve HIV-infected patients regarding arterial elasticity. From September 2010 to September 2015, 105 HIV-infected subjects were enrolled, 41 ART-naïve and 64 on ART with stable viral suppression. Elasticity of large and small arteries (LAE and SAE) was assessed by analysis of radial pulse waveforms using a calibrated device. A single set of measurements was performed. Multivariate linear regression models were constructed to estimate independent correlates of arterial elasticity. On-ART and ART-naïve patients were similar with respect to gender, age, body mass index, Framingham cardiovascular risk score, smoking habits, and CD4+ counts. Median time on treatment was 60 months and 79% of patients were on regimens based on non-nucleoside reverse-transcriptase inhibitors. No significant differences in LAE and SAE assessments were found between groups. However, time on ART and cholesterol levels were independently associated with LAE impairment. No association between arterial elasticity and CD4+ counts was found. We conclude that cumulative exposure to ART may play a role on LAE impairment and deserves further investigation.

El riesgo cardiovascular está incrementado en los pacientes HIV seropositivos y se ha convertido en una de las principales causas de morbimortalidad en esta población. El objetivo de este estudio fue comparar la elasticidad de grandes y pequeñas arterias (LAE y SAE) en pacientes infectados por HIV con y sin terapia antirretroviral. De septiembre de 2010 a septiembre de 2015 se enrolaron 105 pacientes con infección por HIV, 41 vírgenes de antirretrovirales y 64 con tratamiento estable en supresión viral. LAE y SAE fueron evaluados mediante análisis de la onda de pulso radial. Se construyeron modelos de regresión lineal múltiple para evaluar los predictores independientes de la elasticidad arterial. Los grupos en tratamiento y naïve fueron similares con respecto al sexo, edad, índice de masa corporal, índice de Framingham, tabaquismo y recuento de CD4+. La mediana de tiempo en tratamiento antirretroviral fue 60 meses y el 79% de los pacientes recibieron inhibidores no nucleosídicos. No hubo diferencias significativas entre los grupos en los valores de LAE y SAE. Sin embargo, el tiempo en tratamiento y el nivel de colesterol plasmático se asociaron independientemente con deterioro de LAE. No observamos asociaciones entre la elasticidad arterial y los recuentos de CD4+. Concluimos que la exposición acumulada al tratamiento antirretroviral podría contribuir al deterioro de la LAE. Este hallazgo merece ulterior investigación.

Intraoperative analysis of flow dynamics in arteriovenous composite y grafts

Abstract Objective: Composite graft of left internal thoracic artery and great saphenous vein in revascularization of the left coronary system is a technique well described in literature. The aim of this study is to analyze blood flow dynamics in this configuration of composite graft especially in what concerns left internal thoracic artery's adaptability and influence of great saphenous vein segment on left internal thoracic artery's flow. Methods: Revascularization of left coronary system with composite graft, with left internal thoracic artery revascularizing the anterior interventricular artery and a great saphenous vein segment, anastomosed to the left internal thoracic artery, revascularizing another branch of the left coronary system, was performed in 23 patients. Blood flow was evaluated by transit time flowmetry in all segments of the composite graft (left internal thoracic artery proximal segment, left internal thoracic artery distal segment and great saphenous vein segment). Measures were performed in baseline condition and after dobutamine-induced stress, without and with non-traumatic temporary clamping of the distal segments of the composite graft. Results: Pharmacological stress resulted in increase of blood flow values in the analyzed segments (P<0.05). Non-traumatic temporary clamping of great saphenous vein segment did not result in statistically significant changes in the flow of left internal thoracic artery distal segment, both in baseline condition and under pharmacological stress. Similarly, non-traumatic temporary clamping of left internal thoracic artery distal segment did not result in statistically significant changes in great saphenous vein segment flow. Conclusion: Composite grafts with left internal thoracic artery and great saphenous vein for revascularization of left coronary system, resulted in blood flow dynamics with physiological adaptability, both at rest and after pharmacological stress, according to demand. Presence of great saphenous vein segment did not alter physiological blood flow dynamics in distal segment of left internal thoracic artery.

Prognostic Value of Pulmonary Vascular Resistance by Magnetic Resonance in Systolic Heart Failure / Valor Prognóstico da Resistência Vascular Pulmonar através de Ressonância Magnética em Insuficiência Cardíaca

Abstract Background: Pulmonary hypertension is associated with poor prognosis in heart failure. However, non-invasive diagnosis is still challenging in clinical practice. Objective: We sought to assess the prognostic utility of non-invasive estimation of pulmonary vascular resistances (PVR) by cardiovascular magnetic resonance to predict adverse cardiovascular outcomes in heart failure with reduced ejection fraction (HFrEF). Methods: Prospective registry of patients with left ventricular ejection fraction (LVEF) < 40% and recently admitted for decompensated heart failure during three years. PVRwere calculated based on right ventricular ejection fraction and average velocity of the pulmonary artery estimated during cardiac magnetic resonance. Readmission for heart failure and all-cause mortality were considered as adverse events at follow-up. Results: 105 patients (average LVEF 26.0 ±7.7%, ischemic etiology 43%) were included. Patients with adverse events at long-term follow-up had higher values of PVR (6.93 ± 1.9 vs. 4.6 ± 1.7estimated Wood Units (eWu), p < 0.001). In multivariate Cox regression analysis, PVR ≥ 5 eWu(cutoff value according to ROC curve) was independently associated with increased risk of adverse events at 9 months follow-up (HR2.98; 95% CI 1.12-7.88; p < 0.03). Conclusions: In patients with HFrEF, the presence of PVR ≥ 5.0 Wu is associated with significantly worse clinical outcome at follow-up. Non-invasive estimation of PVR by cardiac magnetic resonance might be useful for risk stratification in HFrEF, irrespective of etiology, presence of late gadolinium enhancement or LVEF.

Resumo Fundamento: A hipertensão pulmonar está associada a mau prognóstico em insuficiência cardíaca. No entanto, o diagnóstico não-invasivo é desafiador na prática clínica. Objetivo: Avaliar a utilidade prognóstica da estimativa não-invasiva das resistências vasculares pulmonares (RVP) medidas através de ressonância magnética cardiovascular na previsão de desfechos cardiovasculares adversos em insuficiência cardíaca com fração de ejeção reduzida (ICFEr). Métodos: Registro prospectivo de pacientes com fração de ejeção do ventrículo esquerdo (FEVE) < 40% internados recentemente por insuficiência cardíaca descompensada, durante três anos. As RVP foram calculadas com base na fração de ejeção do ventrículo esquerdo e velocidade média do fluxo na artéria pulmonar estimada por ressonância magnética cardíaca. Durante a evolução, reinternação por insuficiência cardíaca e mortalidade por todas as causas foram consideradas eventos adversos. Resultados: Foram incluídos 105 pacientes (FEVE média de 26,0 ± 7,7%, etiologia isquêmica em 43%). Os valores de RVP nos pacientes que apresentaram eventos adversos durante o seguimento em longo prazo foram mais altos (6,93 ± 1,9 versus 4,6 ± 1,7 unidades Wood estimadas (uWe), p < 0,001). Na análise de regressão multivariada de Cox, RVP ≥ 5 eWu (valor de corte segundo a curva ROC) mostrou-se independentemente associada a um maior risco de eventos adversos aos 9 meses de seguimento (RR = 2,98; IC 95% = 1,12-7,88; p < 0,03). Conclusões: Em pacientes com ICFEr, a presença de RVP ≥ 5,0 uW está associada a uma evolução clínica significativamente pior. A estimativa não-invasiva da RVP através de ressonância magnética cardíaca pode ser útil na estratificação de risco em ICFEr, independentemente da etiologia, presença de realce tardio pelo gadolínio ou FEVE.

The Effect of Pulsatility Index on Infarct Volume in Acute Lacunar Stroke

PURPOSE: Lacunar stroke, in the context of small vessel disease, is a type of cerebral infarction caused by occlusion of a penetrating artery. Pulsatility index (PI) is an easily measurable parameter in Transcranial Doppler ultrasound (TCD) study. PI reflects distal cerebral vascular resistance and has been interpreted as a surrogate marker of small vessel disease. We hypothesized that an increased PI, a marker of small vessel disease, might be associated with a larger infarct volume in acute lacunar stroke. MATERIALS AND METHODS: This study included 64 patients with acute lacunar stroke who underwent TCD and brain MRI. We evaluated the association between the mean PI value of bilateral middle cerebral arteries and infarct volume on diffusion-weighted MRI using univariate and multivariate linear regression. RESULTS: The mean infarct volume and PI were 482.18±406.40 mm3 and 0.86±0.18, respectively. On univariate linear regression, there was a significant positive association between PI and infarct volume (p=0.001). In the multivariate model, a single standard deviation increase of PI (per 0.18) was associated with an increase of 139.05 mm3 in infarct volume (95% confidence interval, 21.25 to 256.85; p=0.022). CONCLUSION: We demonstrated that PI was an independent determinant of infarct volume in acute lacunar stroke. The PI value measured in acute stroke may be a surrogate marker of the extent of ischemic injury.

Andreas Vesalius as a renaissance innovative neuroanatomist: his 5th centenary of birth / Andreas Vesalius como neuroanatomista inovador renascentista: seu 5° centenário de nascimento

Andreas Vesalius (1514-1564) is considered the Father of Modern Anatomy, and an authentic representative of the Renaissance. His studies, founded on dissection of human bodies, differed from Galeno, who based his work on dissection of animals, constituted a notable scientific advance. Putting together science and art, Vesalius associated himself to artists of the Renaissance, and valued the images of the human body in his superb work De Humani Corporis Fabrica.This paper aims to honor this extraordinary European Renaissance physician and anatomist, who used aesthetic appeal to bind text and illustration, science and art. His achievements are highlighted, with an especial attention on neuroanatomy. Aspects about his personal life and career are also focused.

Andreas Vesalius (1514-1564) é considerado o Pai da Anatomia Moderna e um autêntico representante da Renascença. Seus estudos, baseados na dissecação de corpos humanos, diferiam dos de Galeno, que baseava seu trabalho em dissecação de animais, constituiu-se em um notável avanço científico. Reunindo ciência e arte, Vesalius associou-se a artistas da Renascença e valorizou as imagens do corpo humano em seu soberbo trabalho De Humani Corporis Fabrica. Este artigo visa honrar esse extraordinário médico e anatomista da Renascença europeia, que fez uso do apelo estético para coligar texto e ilustração, ciência e arte. Suas realizações são realçadas, com atenção especial na neuroanatomia. Também são colocados em foco aspectos da sua vida pessoal e de sua carreira.

Doppler flowmetry of ophthalmic arteries for prediction of pre-eclampsia / Dopplerfluxometria de artérias oftálmicas para predição de pré-eclâmpsia

Background: central nervous system (CNS) hyperperfusion is one of the events that constitute the pathophysiological basis for the clinical manifestations and complications of pre-eclampsia (PE). Detecting the increased flow in the CNS through Doppler flowmetry of the ophthalmic artery might precede the clinical onset of PE and could be used as a marker for subsequent development of PE. Objective: to evaluate the ophthalmic artery resistive index (OARI) values in the second trimester of pregnancy for prediction of the clinical manifestations of PE. Objective: to evaluate the ophthalmic artery resistive index (OARI) values in the second trimester of pregnancy for prediction of the clinical manifestations of PE. Methods: a total of 73 patients with risk factors for the development of PE were selected from the prenatal service at the HC-UFMG. They were submitted to ophthalmic artery Doppler flowmetry between 24 and 28 weeks of pregnancy and monitored until the end of the pregnancy to verify the occurrence of PE. ROC curves were created to determine the predictive characteristics of the OARI. Results: fourteen of the patients selected developed PE and 59 remained normotensive until the postpartum period. Patients with subsequent development of PE presented OARI values lower than patients that remained normotensive (0.682±0.028 X 0.700±0.029, p=0.044). Considering the development of PE as an outcome, the area under the OARI curve was 0.694 (CI 0.543 to 0.845), with no points obtaining good values of sensitivity or specificity. Conclusion: Doppler flowmetry of ophthalmic arteries between 24 and 28 weeks of pregnancy did not present itself as a good exam for predicting PE. .

Introdução: a hiperperfusão do sistema nervoso central (SNC) é um dos eventos que constitui substrato fisiopatológico para as manifestações clínicas e complicações da pré-eclâmpsia (PE). O fluxo aumentado no SNC, detectado por meio da dopplerfluxometria de artérias oftálmicas, poderia anteceder as manifestações clínicas da PE e, consequentemente, ser utilizado como marcador de subsequente desenvolvimento de PE. Objectivo: avaliar os valores do índice de resistência das artérias oftálmicas (Irao) no segundo trimestre gestacional para a predição das manifestações clínicas da PE. Métodos: pacientes com fatores de risco para desenvolvimento de PE foram selecionadas no serviço de pré-natal do Hospital das Clínicas da Universidade Federal de Minas Gerais (HC-UFMG). Elas foram submetidas à dopplerfluxometria de artérias oftálmicas entre 24 e 28 semanas de gestação e acompanhadas até o final da gestação para averiguar a ocorrência de PE. Curvas ROC foram criadas para determinar as características preditivas do Irao. Resultados: das pacientes selecionadas, 14 desenvolveram PE e 59 mantiveram-se normotensas até o puerpério. Pacientes com subsequente desenvolvimento de PE apresentaram valores de Irao menores do que pacientes que se mantiveram normotensas (0,682±0,028 vs. 0,700±0,029, p=0,044). Ao considerar o desenvolvimento de PE como desfecho, a área sobre a curva do Irao foi de 0,694 (IC 0,543-0,845), sem pontos com bons valores de sensibilidade ou especificidade. Conclusão: a dopplerfluxometria de artérias oftálmicas entre 24 e 28 semanas de gestação não se demonstrou um bom exame para a predição de PE. .

Influence of population and exercise protocol characteristics on hemodynamic determinants of post-aerobic exercise hypotension

Due to differences in study populations and protocols, the hemodynamic determinants of post-aerobic exercise hypotension (PAEH) are controversial. This review analyzed the factors that might influence PAEH hemodynamic determinants, through a search on PubMed using the following key words: “postexercise” or “post-exercise” combined with “hypotension”, “blood pressure”, “cardiac output”, and “peripheral vascular resistance”, and “aerobic exercise” combined only with “blood pressure”. Forty-seven studies were selected, and the following characteristics were analyzed: age, gender, training status, body mass index status, blood pressure status, exercise intensity, duration and mode (continuous or interval), time of day, and recovery position. Data analysis showed that 1) most postexercise hypotension cases are due to a reduction in systemic vascular resistance; 2) age, body mass index, and blood pressure status influence postexercise hemodynamics, favoring cardiac output decrease in elderly, overweight, and hypertensive subjects; 3) gender and training status do not have an isolated influence; 4) exercise duration, intensity, and mode also do not affect postexercise hemodynamics; 5) time of day might have an influence, but more data are needed; and 6) recovery in the supine position facilitates systemic vascular resistance decrease. In conclusion, many factors may influence postexercise hypotension hemodynamics, and future studies should directly address these specific influences because different combinations may explain the observed variability in postexercise hemodynamic studies.

Sildenafil vs. Nitroprussiato de Sódio durante Teste de Reatividade Pulmonar pré-transplante cardíaco / Sildenafil vs. sodium before nitroprusside for the pulmonary hypertension reversibility test before cardiac transplantation

FUNDAMENTO: A hipertensão pulmonar é associada ao pior prognóstico no pós-transplante cardíaco. O teste de reatividade pulmonar com Nitroprussiato de Sódio (NPS) está associado a elevados índices de hipotensão arterial sistêmica, disfunção ventricular do enxerto transplantado e elevadas taxas de desqualificação para o transplante. OBJETIVO: Neste estudo, objetivou-se comparar os efeitos do Sildenafil (SIL) e NPS sobre variáveis hemodinâmicas, neuro-hormonais e ecocardiográficas durante teste de reatividade pulmonar. MÉTODOS: Os pacientes foram submetidos, simultaneamente, ao cateterismo cardíaco direito, ao ecocardiograma e à dosagem de BNP e gasometria venosa, antes e após administração de NPS (1 - 2 µg/Kg/min) ou SIL (100 mg, dose única). RESULTADOS: Ambos reduziram a hipertensão pulmonar, porém o nitrato promoveu hipotensão sistêmica significativa (Pressão Arterial Média - PAM: 85,2 vs. 69,8 mmHg, p < 0,001). Ambos reduziram as dimensões cardíacas e melhoraram a função cardíaca esquerda (NPS: 23,5 vs. 24,8 %, p = 0,02; SIL: 23,8 vs. 26 %, p < 0,001) e direita (SIL: 6,57 ± 2,08 vs. 8,11 ± 1,81 cm/s, p = 0,002; NPS: 6,64 ± 1,51 vs. 7,72 ± 1,44 cm/s, p = 0,003), medidas pela fração de ejeção ventricular esquerda e Doppler tecidual, respectivamente. O SIL, ao contrário do NPS, apresentou melhora no índice de saturação venosa de oxigênio, medido pela gasometria venosa. CONCLUSÃO: Sildenafil e NPS são vasodilatadores que reduzem, de forma significativa, a hipertensão pulmonar e a geometria cardíaca, além de melhorar a função biventricular. O NPS, ao contrário do SIL, esteve associado a hipotensão arterial sistêmica e piora da saturação venosa de oxigênio.

BACKGROUND: Pulmonary hypertension is associated with a worse prognosis after cardiac transplantation. The pulmonary hypertension reversibility test with sodium nitroprusside (SNP) is associated with a high rate of systemic arterial hypotension, ventricular dysfunction of the transplanted graft and high rates of disqualification from transplantation. OBJECTIVE: This study was aimed at comparing the effects of sildenafil (SIL) and SNP on hemodynamic, neurohormonal and echocardiographic variables during the pulmonary reversibility test. METHODS: The patients underwent simultaneously right cardiac catheterization, echocardiography, BNP measurement, and venous blood gas analysis before and after receiving either SNP (1 - 2 µg/kg/min) or SIL (100 mg, single dose). RESULTS: Both drugs reduced pulmonary hypertension, but SNP caused a significant systemic hypotension (mean blood pressure - MBP: 85.2 vs. 69.8 mm Hg; p < 0.001). Both drugs reduced cardiac dimensions and improved left cardiac function (SNP: 23.5 vs. 24.8%, p = 0.02; SIL: 23.8 vs. 26%, p < 0.001) and right cardiac function (SIL: 6.57 ± 2.08 vs. 8.11 ± 1.81 cm/s, p = 0.002; SNP: 6.64 ± 1.51 vs. 7.72 ± 1.44 cm/s, p = 0.003), measured through left ventricular ejection fraction and tissue Doppler, respectively. Sildenafil, contrary to SNP, improved venous oxygen saturation, measured on venous blood gas analysis. CONCLUSION: Sildenafil and SNP are vasodilators that significantly reduce pulmonary hypertension and cardiac geometry, in addition to improving biventricular function. Sodium nitroprusside, contrary to SIL, was associated with systemic arterial hypotension and worsening of venous oxygen saturation.

Vascular dysfunction by myofibroblast activation in patients with idiopathic pulmonary fibrosis and prognostic significance

In this study, we demonstrated the importance of telomerase protein expression and determined the relationships among telomerase, endothelin-1 (ET-1) and myofibroblasts during early and late remodeling of parenchymal and vascular areas in usual interstitial pneumonia (UIP) using 27 surgical lung biopsies from patients with idiopathic pulmonary fibrosis (IPF). Telomerase+, myofibroblasts α-SMA+, smooth muscle cells caldesmon+, endothelium ET-1+ cellularity, and fibrosis severity were evaluated in 30 fields covering normal lung parenchyma, minimal fibrosis (fibroblastic foci), severe (mural) fibrosis, and vascular areas of UIP by the point-counting technique and a semiquantitative score. The impact of these markers was determined in pulmonary functional tests and follow-up until death from IPF. Telomerase and ET-1 expression was significantly increased in normal and vascular areas compared to areas of fibroblast foci. Telomerase and ET-1 expression was inversely correlated with minimal fibrosis in areas of fibroblast foci and directly associated with severe fibrosis in vascular areas. Telomerase activity in minimal fibrosis areas was directly associated with diffusing capacity of the lung for oxygen/alveolar volume and ET-1 expression and indirectly associated with diffusing capacity of the lungs for carbon monoxide and severe fibrosis in vascular areas. Cox proportional hazards regression revealed a low risk of death for females with minimal fibrosis displaying high telomerase and ET-1 expression in normal areas. Vascular dysfunction by telomerase/ET-1 expression was found earlier than vascular remodeling by myofibroblast activation in UIP with impact on IPF evolution, suggesting that strategies aimed at preventing the effect of these mediators may have a greater impact on patient outcome.

Time course of the hemodynamic responses to aortic depressor nerve stimulation in conscious spontaneously hypertensive rats

The time to reach the maximum response of arterial pressure, heart rate and vascular resistance (hindquarter and mesenteric) was measured in conscious male spontaneously hypertensive (SHR) and normotensive control rats (NCR; Wistar; 18-22 weeks) subjected to electrical stimulation of the aortic depressor nerve (ADN) under thiopental anesthesia. The parameters of stimulation were 1 mA intensity and 2 ms pulse length applied for 5 s, using frequencies of 10, 30, and 90 Hz. The time to reach the hemodynamic responses at different frequencies of ADN stimulation was similar for SHR (N = 15) and NCR (N = 14); hypotension = NCR (4194 ± 336 to 3695 ± 463 ms) vs SHR (3475 ± 354 to 4494 ± 300 ms); bradycardia = NCR (1618 ± 152 to 1358 ± 185 ms) vs SHR (1911 ± 323 to 1852 ± 431 ms), and the fall in hindquarter vascular resistance = NCR (6054 ± 486 to 6550 ± 847 ms) vs SHR (4849 ± 918 to 4926 ± 646 ms); mesenteric = NCR (5574 ± 790 to 5752 ± 539 ms) vs SHR (5638 ± 648 to 6777 ± 624 ms). In addition, ADN stimulation produced baroreflex responses characterized by a faster cardiac effect followed by a vascular effect, which together contributed to the decrease in arterial pressure. Therefore, the results indicate that there is no alteration in the conduction of the electrical impulse after the site of baroreceptor mechanical transduction in the baroreflex pathway (central and/or efferent) in conscious SHR compared to NCR.