The morphologic consequences of systemic training

DIGOXINA E VERAPAMIL INDUZEM HIPERTROFIA EM CARDIOMIÓCITOS DE RATOS SEDENTÁRIOS E/OU TREINADOS

RESUMO Introdução: Cardiotônicos e bloqueadores de canais de cálcio são fármacos que alteram o Ca2+ intracelular e afetam o coração. Objetivo: Avaliar os efeitos da administração de verapamil e digoxina sobre a morfologia cardíaca de ratos submetidos ao treinamento intervalado (TAI). Métodos: Ratos Wistar machos divididos em seis grupos (N = 8): Controle, Digoxina (30,0 µg.kg-1/dia), Verapamil (5,0 mg.kg-1/dia), Treinado, Treinado+digoxina e Treinado+verapamil. O TAI foi realizado em esteira rolante (60 min/dia/60 dias) concomitantemente com a administração dos fármacos. Fragmentos do ventrículo esquerdo (VE) foram coletados para análise histológica. Resultados: A digoxina e o verapamil aumentaram a área total do VE (p < 0,002), capilares/área VE (p < 0,01) e área de cardiomiócitos (p < 2,8e-10), sendo que, nesta última variável, o verapamil promoveu efeito ainda maior que a digoxina. O TAI aumentou VE/PC (p < 4e-05), o diâmetro interno do VE (p < 2,7e-6), a área de cardiomiócitos (p < 1,8e-6) e reduziu o [Lac] (p < 2,6e-5). Houve interação entre TAI e fármacos na área total (p < 9,8e-5), capilares (p < 0,04), células/área (p < 0,004) e área de cardiomiócitos (p < 2e-16). Conclusão: A digoxina promoveu hipertrofia de cardiomiócitos e, quando associada ao TAI, potencializou a hipertrofia. O verapamil foi mais eficiente em aumentar a área de cardiomiócitos em comparação com a digoxina, porém somente de forma isolada.

Hypertrophic response of the association of thyroid hormone and exercise in the heart of rats

Background

Cardiac hypertrophy is a component of cardiac remodeling occurring in response to an increase of the activity or functional overload of the heart.

Objective

Assess hypertrophic response of the association of thyroid hormone and exercise in the rat heart.

Methods

We used 37 Wistar rats, male, adults were randomly divided into four groups: control, hormone (TH), exercise (E), thyroid hormone and exercise (H + E); the group received daily hormone levothyroxine sodium by gavage at a dose of 20 μg thyroid hormone/100g body weight, the exercise group took swimming five times a week, with additional weight corresponding to 20% of body weight for six weeks; in group H + E were applied simultaneously TH treatment groups and E. The statistics used was analysis of variance, where appropriate, by Tukey test and Pearson correlation test.

Results

The T4 was greater in groups TH and H + E. The total weight of the heart was greater in patients who received thyroid hormone and left ventricular weight was greater in the TH group. The transverse diameter of cardiomyocytes increased in groups TH, E and H + E. The percentage of collagen was greater in groups E and H + E Correlation analysis between variables showed distinct responses.

Conclusion

The association of thyroid hormone with high-intensity exercise produced cardiac hypertrophy, and generated a standard hypertrophy not directly correlated to the degree of fibrosis.

Effect of parity on maternal cardiac function during the first trimester of pregnancy

OBJECTIVE

To investigate maternal cardiac adaptation in the first trimester of pregnancy with increasing maternal parity.

METHODS

This was a cross-sectional study carried out at the antenatal clinic of a teaching hospital. We examined 4689 pregnant women at 11 + 0 to 13 + 6 weeks of gestation, performing two-dimensional echocardiography of the maternal left ventricle. There were 2352 parous and 2337 nulliparous women. The relationships between parity, maternal cardiac function and neonatal birth weight were analyzed.

RESULTS

Parous compared to nulliparous women had a significantly higher median cardiac output (5.6 vs. 5.2 L/min) and median cardiac index (2.3 vs. 2.1 L/min/m(2)). This was owing to a significantly higher median stroke volume (73.5 vs. 70.5 mL), heart rate (76 vs. 75 bpm), left ventricular outflow diameter (20.4 vs. 20.0 mm) and lower total vascular resistance (1190.8 vs. 1253.7 dyne s/cm(5)) and median uterine artery pulsatility index (1.6 vs. 1.7). Mean arterial blood pressure was not significantly different between the groups. There was a progressive increase in all maternal cardiac variables, apart from total peripheral resistance, which decreased with increasing parity. Birth weight was higher in parous compared to nulliparous women (3.39 vs. 3.23 kg) and it was independently related to maternal hemodynamic variables and demographic and social characteristics (age, height, weight, ethnicity, smoking).

CONCLUSION

Pregnancy in parous compared to nulliparous women is characterized by higher maternal cardiac output and birth weight.

Resistance exercise in individuals with and without cardiovascular disease: 2007 update: a scientific statement from the American Heart Association Council on Clinical Cardiology and Council on Nutrition, Physical Activity, and Metabolism

Prescribed and supervised resistance training (RT) enhances muscular strength and endurance, functional capacity and independence, and quality of life while reducing disability in persons with and without cardiovascular disease. These benefits have made RT an accepted component of programs for health and fitness. The American Heart Association recommendations describing the rationale for participation in and considerations for prescribing RT were published in 2000. This update provides current information regarding the (1) health benefits of RT, (2) impact of RT on the cardiovascular system structure and function, (3) role of RT in modifying cardiovascular disease risk factors, (4) benefits in selected populations, (5) process of medical evaluation for participation in RT, and (6) prescriptive methods. The purpose of this update is to provide clinicians with recommendations to facilitate the use of this valuable modality.

Cardiac Manifestations of Exhaustive Exercise in Nonathletic Adults: Does Cardiac Fatigue Occur?

The aim of the study was to examine the impact of prolonged exercise leading to physical exhaustion on left ventricular (LV) systolic and diastolic function in untrained healthy subjects, and to examine cardiovascular determinants of exercise performance. Twenty-four nonathletic healthy adults (14 males, 10 females; mean age 42 +/- 11 years) were exercised on a treadmill at 70% of maximal oxygen consumption until physical exhaustion occurred after an average of 84 +/- 39 minutes. Two-dimensional and Doppler echocardiography was performed before and 15 minutes after exercise to assess LV function and geometry, and right ventricular (RV) systolic function. After prolonged exercise, LV ejection fraction and geometry were unchanged, but LV end-diastolic volume, end-systolic volume, and stroke volume decreased. However, due to a higher heart rate (HR), cardiac output increased at 15 minutes post exercise. RV fractional shortening was unchanged. LV peak early to atrial filling velocity ratio decreased post exercise, with an increase in percent atrial contribution. However, less preload-dependent variables of LV diastolic function such as deceleration time, LV inflow propagation rate, mitral annular tissue Doppler and myocardial performance index were unchanged. Preexercise stroke volume and HR were the only predictors (r = 0.86, P < 0.01) of exercise duration. However, age, resting blood pressure, indices of systolic and diastolic function, and LV geometry were not predictors. Prolonged exercise leading to physical exhaustion is not associated with systolic or diastolic dysfunction. Reduced early LV diastolic filling and the relative increase in left atrial contribution seen with prolonged exercise are likely due to preload reduction rather than true diastolic dysfunction.

Effects of angiotensin-converting enzyme polymorphism on aortic elastic parameters in athletes

BACKGROUND

Physiologic adaptations in an athlete's heart include increased left and right ventricular chamber size, left ventricular wall thickness and mass. Angiotensin-converting enzyme (ACE) is a key enzyme in angiotensin II production causing cardiac hypertrophy. The cloning of the ACE gene has made it possible to identify a deletion (D)-insertion (I) polymorphism that appears to affect the level of serum ACE activity. Therefore, the ACE genes, which have been shown to be polymorphic, could be candidate genes for large-artery stiffness.

METHODS

56 endurance athletes and 46 sedentary subjects were included in this study, and they underwent both complete echocardiographic examination, and analysis of ACE insertion (I) and deletion (D) allele frequencies in peripheral blood. The aortic diameter was recorded by M-mode echocardiography at a level 3 cm above the aortic valve. Aortic systolic diameter was measured at the time of full opening of the aortic valve, and diastolic diameter was measured at the peak of QRS. Aortic strain, stiffness index and distensibility were calculated.

RESULTS

Left ventricular mass index and left ventricular ejection fraction were significantly higher in athletes than controls (p < 0.001). The aortic distensibility index and strain were significantly greater in athletes compared with controls (respectively: 5.8 +/- 2.7 vs. 4.7 +/- 1.8 cm(-2) dyn(-1) 10(-6), p = 0.017; 12.3 +/- 2.4 vs. 9.3 +/- 3.1, p < 0.001). The aortic stiffness index was significantly lower in athletes than in controls (4.8 +/- 1.9 vs. 6.1 +/- 2.1, p < 0.001). The aortic distensibility index and strain were statistically different in ACE DD vs. DI groups and DD vs. II groups of athletes. The aortic stiffness index was statistically different in ACE DD vs. II groups of athletes. Aortic parameters were similar according to ACE genotypes in controls.

CONCLUSION

The results of this study indicate that aortic distensibility was increased by prolonged training in endurance athletes, particularly in those with the ACE II genotype. This effect represents an extracardiac adaptation to chronic prolonged training in athletes.

Features of cardiac disease demonstrated on CT pulmonary angiography

The heart and mediastinal structures can be overlooked at CT pulmonary angiogram (CTPA). This pictorial review will demonstrate the features of cardiac disease that may be evident on a CTPA. CTPA allows assessment of not only the pulmonary arteries for embolism, but also of the bronchi, lung parenchyma, mediastinum and heart. Co-existent underlying or incidental cardiac disease is often present. Potentially life-threatening alternative diagnoses in a patient with chest symptoms can be reliably identified. Pathologies of the myocardium including hypertrophic cardio myopathy, pericardial disease, valvular disease, coronary artery disease, and intracardiac abnormalities are demonstrated pictorially. CTPA is increasingly used for the detection of pulmonary embolism. Most patients investigated have pathology other than PE as a cause of their symptoms. Frequently information about the heart is produced that provides important clues to determine the cause for the presenting symptoms and signs or reveals co-existing pathology. It is important to have a clear understanding of the features of cardiac disease which may be seen on a CTPA.

Physiological effects of exercise on the cardiopulmonary system

The cardiopulmonary adaptations made to dynamic and static exercise show the amazing ability of the human body to alter physiological processes in order to meet metabolic demands. A remarkable partnership that allows individuals to maximize their abilities and obtain goals exists between the cardiovascular and pulmonary systems. The adaptations of the cardiopulmonary system depend heavily on the intensity, duration, frequency, and type of exercise being performed. Although most of this article examined dynamic and static exercise separately, the majority of individuals train using a combination of these two modes. The overall adaptations will vary with the chosen degree of each exercise mode. An appropriate exercise program allows for improvements in the cardiopulmonary system that help develop and maintain fitness levels.

[Heart and sports: modifications of electrocardiogram, late potentials and echocardiography. Study of 75 sportsmen and 46 witnesses]

The authors report the results of prospective study, which compared 75 sports subjects and 45 witnesses. All subjects were male, the differentiating parameter being the type of sport practiced. This work analysed surface Electrocardiogramme, thransthoracic echocardiography and high amplification ECG. The statistical study used the student test t compare means and the Chi2 test for the percentages, the signification limit was fixed to 5%. Clinically, our two series didn't show a significant statistical difference, concerning: age, weight, height or arterial pressure. On the electrocardiographical level, the sport's men have a lower cardiac frequency (p = 0.005), a larger PR space (p = 0.05), an important Sokolow parameter (p < 0.005), and repolarisation disorders represented, essentially by negative T waves (p = 0.02) and an upper movement of ST segment in V2-V3 (p < 0.005). Echocardiography showed a dilatation of the right cavities: right auricular (p = 0.0125) and right ventricular (p = 0.025). Move over, it has been showed that the sport's men left ventricular walls were tabor (septal wall, p = 0.0125), (posterior wall, p = 0.025), despite a difference in the values of the left ventricular telediastolic diameter (4 mm average in the two series). The signification limit was not reached and it was also showed that the left auricular was also dilated (p = 0.025). The study of the delayed Potentials, tried to bring an explication to certain sudden deaths of sport's men which are to date unexplained and which could have a rhythmical origin? It is also to be noted that sport's men present more delayed ventricular Potentials. However, the statistical signification was not reached (p = 0.07).

Maternal left ventricular mass and diastolic function during pregnancy

OBJECTIVE

To evaluate changes in left ventricular mass and diastolic function during normal pregnancy.

METHODS

This was a cross-sectional study of 125 pregnant women at 9-42 weeks of gestation and 19 non-pregnant female controls. Two-dimensional and M-mode echocardiography of the maternal left ventricle and left atrium was performed.

RESULTS

During pregnancy left ventricular mass increased by 52%. There was an increase in left ventricular end-diastolic and end-systolic diameters (12% and 20%, respectively), left ventricular posterior wall diameter during diastole and systole (22% and 13%, respectively) and left intraventricular septum during diastole and systole (15% and 19%, respectively). Mitral valve A-wave maximum velocity increased during pregnancy by 19%, while mitral valve E-wave maximum velocity and the ratio of E-wave/A-wave velocities increased early in pregnancy by about 14% and 6%, respectively, with a subsequent decline to 4% and 10%, respectively, below non-pregnant levels.

CONCLUSION

Left ventricular mass increases during pregnancy, while left ventricular diastolic function, as demonstrated by the changes in mitral valve flow velocities, increases in the first two trimesters but declines in the third trimester.

Asymmetric redirection of flow through the heart

Through cardiac looping during embryonic development, paths of flow through the mature heart have direction changes and asymmetries whose topology and functional significance remain relatively unexplored. Here we show, using magnetic resonance velocity mapping, the asymmetric redirection of streaming blood in atrial and ventricular cavities of the adult human heart, with sinuous, chirally asymmetric paths of flow through the whole. On the basis of mapped flow fields and drawings that illustrate spatial relations between flow paths, we propose that asymmetries and curvatures of the looped heart have potential fluidic and dynamic advantages. Patterns of atrial filling seem to be asymmetric in a manner that allows the momentum of inflowing streams to be redirected towards atrio-ventricular valves, and the change in direction at ventricular level is such that recoil away from ejected blood is in a direction that can enhance rather than inhibit ventriculo-atrial coupling. Chiral asymmetry might help to minimize dissipative interaction between entering, recirculating and outflowing streams. These factors might combine to allow a reciprocating, sling-like, 'morphodynamic' mode of action to come into effect when heart rate and output increase during exercise.