Antihypertensive treatments obscure familial contributions to blood pressure variation

The linkage and association between inherent blood pressure and underlying genotype is potentially confounded by antihypertensive treatment. We estimated blood pressure variance components (genetic, shared environmental, individual-specific) in 767 adult volunteer families by using a variety of approaches to adjusting blood pressure of the 244 subjects (8.2%) receiving antihypertensive medications. The additive genetic component of variance for systolic pressure was 73.9 mm Hg(2) (SE, 8.8) when measured pressures (adjusted for age by gender within each generation) were used but fell to 61.4 mm Hg(2) (SE, 8.0) when treated subjects were excluded. When the relevant 95th percentile values were substituted for treated systolic pressures, the additive genetic component was 81.9 mm Hg(2) (SE, 9.5), but individual adjustments in systolic pressure ranged from -53.5 mm Hg to +64.5 mm Hg (mean, +17.2 mm Hg). Instead, when 10 mm Hg was added to treated systolic pressure, the additive genetic component rose to 86.6 mm Hg(2) (SE, 10.1). Similar changes were seen in the shared environment component of variance for systolic pressure and for the combined genetic and shared environmental (ie, familial) components of diastolic pressure. There was little change in the individual-specific variance component across any of the methods. Therefore, treated subjects contribute important information to the familial components of blood pressure variance. This information is lost if treated subjects are excluded and obscured by treatment effects if unadjusted measured pressures are used. Adding back an appropriate increment of pressure restores familial components, more closely reflects the pretreatment values, and should increase the power of genomic linkage and linkage disequilibrium analyses.

Familial and genomic analyses of postural changes in systolic and diastolic blood pressure

The physiological adaptation to the erect posture involves integrated neural and cardiovascular responses that might be determined by genetic factors. We examined the familial- and individual-specific components of variance for postural changes in systolic and diastolic blood pressure in 767 volunteer nuclear adult families from the Victorian Family Heart Study. In 274 adult sibling pairs, we made a genome-wide scan using 400 markers for quantitative trait loci linked with the postural changes in systolic and diastolic pressures. Overall, systolic pressure did not change on standing, but there was considerable variation in this phenotype (SD=8.1 mm Hg). Familial analyses revealed that 25% of the variance of change in systolic pressure was attributable to genetic factors. In contrast, diastolic pressure increased by 6.3 mm Hg (SD=7.0 mm Hg) on standing and there was no evidence of contributory genetic factors. Multipoint quantitative genome linkage mapping suggested evidence (Z=3.2) of linkage of the postural change in systolic pressure to chromosome 12 but found no genome-wide evidence of linkage for the change in diastolic pressure. These findings suggest that genetic factors determine whether systolic pressure decreases or increases when one stands, possibly as the result of unidentified alleles on chromosome 12. The genetics of postural changes in systolic blood pressure might reflect the general buffering function of the baroreflex; thereby, the predisposition to sudden decreases or increases in systolic pressure might cause postural hypotension or vessel wall disruption, respectively.

Cardiac adaptation to endurance exercise in rats

Endurance exercise is widely assumed to improve cardiac function in humans. This project has determined cardiac function following endurance exercise for 6 (n = 30) or 12 (n = 25) weeks in male Wistar rats (8 weeks old). The exercise protocol was 30 min/day at 0.8 km/h for 5 days/week with an endurance test on the 6th day by running at 1.2 km/h until exhaustion. Exercise endurance increased by 318% after 6 weeks and 609% after 12 weeks. Heart weight/kg body weight increased by 10.2% after 6 weeks and 24.1% after 12 weeks. Echocardiography after 12 weeks showed increases in left ventricular internal diameter in diastole (6.39 ± 0.32 to 7.90 ± 0.17 mm), systolic volume (49 ± 7 to 83 ± 11 μl) and cardiac output (75 ± 3 to 107 ± 8 ml/min) but not left wall thickness in diastole (1.74 ± 0.07 to 1.80 ± 0.06 mm). Isolated Langendorff hearts from trained rats displayed decreased left ventricular myocardial stiffness (22 ± 1.1 to 19.1 ± 0.3) and reduced purine efflux during pacing-induced workload increases. 31P-NMR spectroscopy in isolated hearts from trained rats showed decreased PCr and PCr/ATP ratios with increased creatine, AMP and ADP concentrations. Thus, this endurance exercise protocol resulted in physiological hypertrophy while maintaining or improving cardiac function.

Effects of weight loss on the cardiac parameters of obese dogs

A obesidade é uma das doenças nutricionais mais frequentemente observada em cães e pode provocar sérios problemas de saúde, como os distúrbios cardiovasculares. Realizou-se este estudo visando avaliar algumas das possíveis alterações estruturais e funcionais cardíacas decorrentes da correção da obesidade canina. Para isso foram utilizados 18 cães obesos divididos pelo peso corporal em Grupo I (até 15kg), Grupo II (entre 15,1 e 30 kg) e Grupo III (acima de 30 kg). Os animais foram submetidos à restrição calórica de forma a perderem 15% do peso vivo. Foram realizados os exames ecocardiográfico em modo-M, eletrocardiográfico e mensuração da pressão arterial dos animais antes do início do tratamento da obesidade e após atingirem o peso meta. Os resultados revelaram que após a redução de peso ocorreram diminuições significativas da espessura da parede livre do ventrículo esquerdo durante a sístole e diástole no Grupo III, diminuição da pressão arterial sistólica no Grupo III e também da pressão arterial média no Grupo II. Assim, concluiu-se que a perda de peso pode reverter as alterações estruturais cardíacas, como a hipertrofia excêntrica do ventrículo esquerdo em cães obesos acima de 30 kg, como também reduzir a pressão arterial sistêmica em cães obesos submetidos à restrição calórica mediante administração de dieta hipocalórica.

Alterações ecocardiográficas em cães sob tratamento prolongado com doxorrubicina

Avaliou-se a cardiotoxicidade da doxorrubicina utilizando-se sete cães adultos, clinicamente normais, que receberam 30mg/m² de cloridrato de doxorrubicina (Adriblastina®) por via intravenosa, a cada 21 dias, durante 168 dias (grupo A), perfazendo dose cumulativa total de 240mg/m². em outros sete cães (grupo B) administraram-se 5ml de solução salina 0,9% estéril por via intravenosa, seguindo-se o esquema de aplicação proposto anteriormente. Os animais foram avaliados, periodicamente, por meio de exames ecocardiográficos em modo-M e bidimensional. Verificou-se aumento (P<0,01) no diâmetro e volume do ventrículo esquerdo, inicialmente em sístole e, posteriormente, em diástole, hipocinesia do septo interventricular e da parede livre do ventrículo esquerdo, reduções de aproximadamente 65% nas frações de encurtamento e de ejeção, além de aumento da separação do septo do ponto E do folheto anterior da válvula mitral nos animais do grupo A. As alterações cardíacas decorrentes do tratamento crônico com doxorrubicina foram semelhantes àquelas descritas em cães com cardiomiopatia dilatada, e os índices ecocardiográficos puderam ser utilizados no acompanhamento e na prevenção da cardiotoxicidade pelo quimioterápico.

Comportamento de mergulho do boto-cinza, Sotalia guianensis, na enseada do Curral, Praia de Pipa-RN, Brasil :possíveis adaptações cardíacas ao mergulho

The marine tucuxi, Sotalia guianensis, is one of the smallest known cetaceans, has coastal habits, and occurs from Hondures to Santa Catarina, in southern Brazil. The objective of this dissertation was to describe diving behavior of the marine tucuxi in three age classes and to analyze the cardiac capacity to dive through the examination of hearts of stranded specimens. Observations were made from October 2004 to November 2005 from a vantage point, in Curral Bay at Pipa beach-RN. We used Ad Libitum sampling and All occurrences to record the behaviors. The diving was characterized by the total exposition of the tail fluke for a few seconds, in 90° or 45° angles. Were recorded 131 dives in three behavioral contexts: foraging, traveling and socialization. The difference between juveniles and adults in dive time and fluke out at 45° or 90° to search and/or capture prey is probably influenced by the strategy used and ability to capture the prey. The frequency of fluke out at 90° for foraging in adults may be related to increased physiological efficiency of adults in comparison to juveniles. However, in the context of travel and socialization the dive time and fluke out were independent between the age classes. Dive in calves were frequent during socialization (play behavior) and traveling. This, associated with synchronic calve-adult diving suggests that a relationship of these behaviors and the acquisition of experience and foraging skills. As observed in other cetaceans, the heart (n=12) of the estuarine dolphin is broad and presents long ventricles which form a round apex. The right ventricle is long and narrow. The degree of dilatation of the aortic bulb may support the heart during diastole. The characteristic morphology of the heart and short dive duration < 2 min and depth ranged from 10m in the estuarine dolphin, can be likely at physiological adaptation for diving, typical de dolphins with coastal habits. The limitation of diving time in this specie may be influenced by anatomical and physiological restrictions

Echocardiographic abnormalities in children with obstructive breathing disorders during sleep

Objectives: To assess cardiac morphology and function by means of echocardiograms of children with obstructad breathing while asleep.Methods: the study enrolled 40 children of both sexes, aged from 3 to 11 years; 30 of them had obstructed breathing during sleep (group I) and 10 children were healthy controls (group II). The two groups were similar in terms of sex, age, weight and height. The 40 children underwent echocardiogram, viewing all four chambers during systole and diastole, paying special attention to the right ventricle (RV). These data were compared by means of Student's t test (p < 0.05).Results: In group I, increased diameter and area of the right ventricle were observed during both systole and diastole. There was less variation in RV area between systole and diastole. Reduced left ventricle (LV) diastolic diameter was also observed, together with reduced ejection fraction and reduced contraction.Conclusions: the morphological and functional cardiac abnormalities observed in the RV and LV suggest that, in children, obstructed breathing during sleep can lead to cardiovascular repercussions. These abnormalities may expose these children to increased anesthetic and surgical risks.

Insuficiência cardíaca com fração de ejeção normal

A insuficiência cardíaca com fração de ejeção normal (ICFEN) é uma síndrome complexa que vem sendo largamente estudada, desde a última década. É causada por disfunção ventricular diastólica evidenciada por métodos complementares, como estudo hemodinâmico ou ecocardiograma, na presença de fração de ejeção preservada. Acomete preferencialmente indivíduos mais idosos e com comorbidades, como hipertensão arterial sistêmica, insuficiência coronariana e obesidade. Os mecanismos fisiopatológicos são complexos e multifatoriais, envolvendo a rigidez passiva do miocárdio, a geometria ventricular, a força de contenção do pericárdio e a interação entre os ventrículos. Os objetivos principais do tratamento são reduzir a congestão venosa pulmonar, a frequência cardíaca e controlar as comorbidades. Ainda não há evidências fortes de que o uso de medicações específicas, como inibidores de enzima de conversão ou betabloqueadores, interfiram na mortalidade. Os fatores de pior prognóstico incluem a idade avançada, presença de disfunção renal, diabete, classe funcional III e IV (NYHA) e estágio avançado de disfunção diastólica, com padrão restritivo ao enchimento ventricular. Outro aspecto que vem ganhando espaço na literatura é o questionamento do papel da disfunção sistólica nos quadros de ICFEN. Todos esses aspectos são abordados detalhadamente na presente revisão.

CLINICAL STUDY of NATURAL INFECTION BY Trypanosoma cruzi IN DOGS RESIDING IN A RURAL AREA IN MATO GROSSO do SUL STATE, BRAZIL

This study was carried out to describe the clinical characteristics of natural infection caused by Trypanosoma cruzi in dogs that reside in a rural area of Mato Grosso do Sul State, Brazil. Conventional and nonconventional diagnostic methods were used for screening T. cruzi infection in 75 dogs that lived in the area. Cardiovascular tests and biochemical examination of sera were also performed in four confirmed positive dogs. The following techniques were employed: indirect immunofluorescence test (IFAT), enzyme-linked immunosorbent assay with T. cruzi epimastigote antigens (EAE-ELISA) and enzyme-linked immunosorbent assay with T. cruzi excreted-secreted trypomastigote antigens (TESA-ELISA) with antibodies detected in 45.33% (n = 34), 24.0% (n = 18) and 12.0% (n = 9) of the dogs, respectively. The current prevalence of the infection was confirmed as 10.7% (n = 8) by immunoblotting test with T. cruzi excreted-secreted antigens (TESA-blot). The test that showed the best concordance index (Kappa; 0.93), sensitivity (100%) and specificity (98.5%) was TESA-ELISA, that when associated with IFAT had the same results as those obtained by TESA-blot (10.7%). Three out of the four chagasic animals showed enlarged cardiac silhouette on X-ray and an increase of the P-wave duration and QRS complex in electrocardiogram. Two dogs presented conduction disturbances, right bundle branch block in one dog and first-degree atrioventricular block and sinus arrest in another. The ecodopplercardiography presented left-ventricular-wall thickness increased during diastole, decrease of the shortening fraction and inversion in the speed peaks of the E and A waves, indicating the presence of systolic and diastolic disorders. The four animals showed enzymatic activities of creatine kinase (221-404 U/L), MB fraction of creatine kinase (189-304 U/L), elevated total proteins (7.6-10.2 g/dL) and total globulins (4.6-7.7g/dL) and reduction of albumin/globulin ratio, which suggested a myocardial injury and continuous antigenic stimulus.

Systemic hypertension in patients with glomerulonephritis

Although systemic hypertension is very common in patients with glomerulonephritis there is a dispute if this alteration is consequence of the glomerulonephritis per se or is a consequence of the renal failure secondary to the glomerular lesion. With the aim to analyze the factors associated with systemic hypertension, 196 patients with different forms of nephritis were studied. The systemic arterial pressure was measured by standard sphygmomanometer, renal function was evaluated by the determination of the serum creatinine concentration or creatinine clearance. The diagnosis of the type of glomerulonephritis was made on the basis of an examination of kidney biopsy specimens. The prevalence of arterial hypertension among patients with glomerulonephritis was 62.7%. The hypertensive patients were older (hypertensive = 30.6 ± 12.8; normotensive = 25.4 ± 1.6 years; P = 0.03). The prevalence of arterial hypertension was lower in patients with minimal glomerular lesion (12.5%), though their ages were also lower (18.1 ± 3.6 and 29.1 ± 1.03 years; P = 0.03). Arterial hypertension did not correlate with the serum levels of creatinine and albumin; creatinine clearance and 24-h proteinuria. In conclusion: In the patients with glomerulonephritis, the presence of arterial hypertension was associated with a higher mean age whereas the intensity of proteinuria, the level of renal function or the type of glomerulonephritis was not different between the two groups.

A administração precoce de hormônio de crescimento resulta em efeitos deletérios na remodelação ventricular após o infarto agudo do miocárdio

Objective: To assess the effect of growth hormone (GH) on myocardial remodeling in infarcted rats. Methods: This study comprised 24 Wistar rats divided into 3 groups as follows: 1) AMI-GH group - comprising 8 rats that underwent infarction and were treated with GH; 2) AMI group - comprising 8 rats that underwent infarction and received only the diluent of the GH solution; and 3) control group (C group) - comprising 8 rats that underwent simulated infarction. After 30 days, the animals underwent functional study through echocardiography, and the changes in myocardial contractility of the isolated left ventricular (LV) papillary muscle were studied. Results: The echocardiography identified an increase in the diastolic (C=7.32±0.49; AMI=8.50±0.73; AMI-GH=9.34±0.73; P<0.05) and systolic (C=3.38±0.47, AMI=5.16±1.24; AMI-GH=5.96±1.54; P<0.05) diameters (mm) in the LV of the infarcted animals. The AMI-GH group animals had a lower ejection fraction (%) (C=0.9±0.03; AMI=0.76±0.12; AMI-GH=0.72± 0.14; P<0.05 for C vs AMI-GH) compared with those in controls. The study of the isolated left ventricular papillary muscle showed that the AMI-GH group had changes (C=1.50±0.59; AMI= 1.28±0.38; AMI-GH=1.98±0.41; P<0.05 for C vs AMI-GH) only in the tension at rest (TR - g/mm2) and in the time delta for a 50% decrease in the tension developed (TR50, ms) after stimulation with calcium (C=23.75±9.16; AMI=-16.56±14.82; AMI-GH=-4.69±8.39; P<0.05 for C vs AMI-GH) and in the delta of tension developed (TD, g/mm2) after stimulation with isoproterenol (C=0.99±0.17; AMI=0.54±0.62; AMI-GH=0.08±0.75; P<0.05 for C vs AMI-GH) compared with those in control animals. Conclusion: The early administration of GH in the experimental infarction model in rats may result in adverse effects on the process of ventricular remodeling.

Proprioceptive neuromuscular facilitation does not increase blood pressure of healthy elderly women

Proprioceptive neuromuscular facilitation (PNF) is an attractive method to increase strength and proprioception of elderly individuals. However, a major clinical concern about the prescription of PNF is the belief that it can cause a cardiovascular overload, because it involves close-to-maximal loads and isometric contractions. Yet the acute effect of a PNF training session on cardiovascular response in elderly individuals is still unknown. Hence, the objective of this study was to evaluate the effect of PNF on diastolic and systolic blood pressure of healthy elderly people. Fifteen older women (mean age 72.40±6.82 years) performed three sets (five repetitions each) of three different PNF techniques (rhythmic initiation, dynamic reversion, and isotonic combination), executing a single movement pattern. Diastolic and systolic blood pressure (DBP and SBP) were evaluated by means of a manual sphygmomanometer immediately before and during the last two repetitions (last set) of each technique. A two-way ANOVA test (time and technique) was performed to investigate the PNF effect on blood pressure. No time (preexercise to postexercise) (p=0.33 for DBP; p=0.06 for SBP) or PNF technique (p=0.75; p=0.81) effect were observed. In conclusion, we can state that the execution of these PNF techniques is safe for the cardiovascular system of healthy elderly women, because no blood pressure increases were found. Copyright © Informa Healthcare USA, Inc.

Doppler echocardiography in athletes from different sports

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Estudo das lesões laríngeas e do grau de disfonia em pacientes com paracoccidioidomicose

Pós-graduação em Doenças Tropicais - FMB

Influência da deficiência de taurina no coração

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)