Myocardial Contraction – ABC CARDIOL

ABCIC

Systematic Review

Myocardial Work: a Systematic Review of Novel Echocardiography Method and Clinical Applications

Sidhi Laksono et al. Hillary Kusharsamita Mefri Yanni Astri Astuti

Abstract

Background:

Myocardial work (MW) is a novel imaging modality that has emerged as a potential left ventricular (LV) function assessment in various clinical settings. MW calculates speckle-tracking echocardiography strain curves with an estimated LV pressure curve by non-invasively utilizing standard brachial blood pressure curves.

Objective:

This study aimed to provide a summary of current knowledge of non-invasive MW and its clinical applications, including in heart failure, coronary artery disease, cardiomyopathy, and hypertension. In addition, the limitations, and recommendations of MW in clinical practice are discussed.

Methods:

We searched the PubMed database using the following keywords: (myocardial constructive work) OR (wasted septal work) OR (global myocardial work) OR (myocardial work) OR (myocardial constructive work) OR (novel echocardiography). We further subjected 12 studies to full-text review and included them in this systematic review.

Results:

While MW indices, particularly global work index and global constructed work, have shown good correlations with ejection fraction (EF) and strain parameters, the opportunity of offering incremental information that is unaffected by loading conditions has made MW application particularly useful in a variety of clinical settings.

Conclusion:

Compared to EF and global longitudinal strain, MW is a promising test with higher sensitivity and accuracy for identifying individuals with cardiovascular disease. Clinicians should also evaluate symptoms and electrocardiographic findings until extensive multicenter studies validating this strategy are performed to establish the incremental value of MW in daily echocardiographic assessments.

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Editorial

Cardioprotective Effect of Resistance Exercise on Left Ventricular Remodeling Associated with Monocrotaline-Induced Pulmonary Arterial Hypertension

Silvio A. Oliveira-Junior et al. Alex Y. Ogura Marianna R. Carvalho Paula F. Martinez

Pulmonary arterial hypertension (PAH) is characterized by progressive pulmonary vascular resistance, affecting several arteries and arterioles. These changes are associated with increased right ventricular afterload and remodeling, characterized by severe hypertrophy, initially adaptive and derived from vascular pressure gradient.^, Afterward, these alterations are accompanied by right ventricular dilation and impaired contractile performance, resulting in reduced ejection fraction and ventricular failure.^, Clinically, right ventricular size and function parameters alterations have a recognized association with bad prognosis in pulmonary arterial hypertension.

During the PAH development, when right ventricular filling pressure has been increased, and cardiac output is deteriorating, there are concomitant volumetric and pressoric overload into the right ventricle. These effects make the interventricular septum move to the left side, sustaining a paradoxical movement. Next, left ventricle (LV) ejection fraction and diastolic performance are affected, facing impaired early diastolic filling, reduced end-diastolic volume, and adverse remodeling.^, Therefore, LV dysfunction configures a secondary and important effect from PAH onset.^{, ,}

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IJCS

Editorial

Hyperthyroidism and Cardiac Contractility

Dhiãnah Santini de Oliveira Chachamovitz

Much information is lacking on hyperthyroidism and cardiac function, especially in isolated muscles. Certainly, the time the heart muscle is exposed to elevated thyroid hormones (TH) influences the magnitude of their effects. The primary changes seem to be related to increases in the heart mass/body mass ratio and in relaxation kinetics.

These cardiac changes may also be related not only to the time of exposure to excess thyroid hormones, but to the level or intensity of hyperthyroidism, as well as the underlying cardiac condition, which may reflect exercise conditioning and overload. In this sense, the cellular mechanisms of muscle adaptation, energy and oxygen consumption, certainly make differences. As well as muscle strength and sarcoplasmic/endoplasmic reticulum calcium (SRCa) activity, they may also have different individual adaptive characteristics.

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ABCIC

Original Article

Left Ventricular Longitudinal Linear Displacement Versus Global Longitudinal Strain on Cardiovascular Magnetic Resonance

Rafael Almeida Fonseca et al. Sergio Marrone Ribeiro Clerio Francisco de Azevedo Filho Roney Sampaio … Flávio Tarasoutchi Carlos Eduardo Rochitte

Abstract

Background

Left ventricular (LV) systolic diastolic function is prognostic in cardiovascular diseases and can be assessed via global longitudinal strain (GLS) on echocardiography and cardiac magnetic resonance (CMR). However, GLS by CMR requires the use of expensive software. Longitudinal linear displacement (LLD) may be a simple and inexpensive alternative to GLS, but the two have not been systematically compared.

Objective

To compare LLD with GLS and LV ejection fraction (LVEF) in aortic valve disease patients and controls.

Methods

We included 44 participants (26 with aortic valve disease, 19 controls). GLS was determined using CVI42 software (Circle Cardiovascular Imaging), while the LLD linear measurements of the distance between the base/apex of the LV included maximum displacement (MD), maximum velocity in early diastole (MVED), atrioventricular junction velocity in diastasis (VDS), and VDS/MVED ratio.

Results

DM and MVED were correlated with GLS (r=0.69 and r=0.65, respectively) and LVEF (r=0.47 and r=0.57, p<0.001 for both). DM and MVED showed areas under the receiver operating characteristic curve (AUC) of 0.88 and 0.91, and at the best cut-off point (-0.13 and 0.66), sensitivities of 72.43% and 57.14% and specificities of 80.65% and 87.10%, respectively, compared to GLS. Using LVEF as a reference, we obtained AUC of 0.70 and 0.82, and at the best cut-off point (-0.11 and 0.61), sensitivities of 75.00% and 50.00% and specificities of 72.97% and 78.38%, respectively.

Conclusion

LLD demonstrated similar performance to that of GLS. MD derived from LLD was the best parameter during systole, while MVED was the best during diastole. Our findings demonstrate the routine, quick, and inexpensive assessment of diastolic function on CMR.

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Original Article

Effects of Hyperthyroidism on Contractility and Na+/Ca2+ Exchanger Activity in the Isolated Papillary Muscle of Rats

Angela Mara Rambo et al. João Victor Capelli Peixoto Rebeca Alves Lins de Albuquerque Ilana Kassouf Silva Rosalvo Tadeu Hochmueller Fogaça

Abstract

Background:

Hyperthyroidism (Hy) is an endocrine disorder, in which the thyroid hormones markedly alter the cardiac function. Increased myocardial contractility and cardiac output, improvement in diastolic relaxation, changes in electrical activity, increments in ventricular mass, and arrhythmias have been reported. However, the influences of thyroid hormones upon molecular mechanisms of cardiac functions have not yet been fully understood.

Objectives:

To evaluate changes in cardiac contractile parameters and the Na+/Ca2+ exchanger (NCX) function in induced hyperthyroid rats.

Methods:

Hy was induced by intraperitoneal injections of T3 (15 μg/100 g) for 10 days. Contractile parameters and NCX function were evaluated in the isolated papillary muscle. Data normality was confirmed by the Shapiro-Wilk test. The comparison between groups was performed through an unpaired Student’s t-test. Results are expressed as mean ± SD. The accepted significance level was p < 0.05.

Results:

Our data revealed, in the Hy group, an increase of 30.98% in the maximum speed of diastolic relaxation (–284.64 ± 70.70 vs. –217.31 ± 40.30 mN/mm2/sec (p = 0.027)) and a boost of 149% in the NCX function in late phase of relaxation (20.17 ± 7.90 vs. 50.22 ± 11.94 minutes (p = 0.002)), with no changes in the maximum twitch force (p = 0.605) or maximum speed of systolic contraction (p = 0.208) when compared to the control.

Conclusion:

The improvement in relaxation parameters is hypothetically attributed to an increase in Sarco-Endoplasmic Reticulum Ca2+ATPase isoform 2 (SERCA2) expression and an increased calcium flow through L-type channels that boosted the NCX function.

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Original Article

Standard Echocardiography, Strain and Strain Rate by Two-Dimensional Speckle Tracking in Capuchin Monkey (Cebus Apella, Linnaeus, 1758)

Laecio da Silva Moura et al. Renan Paraguassú de Sá Rodrigues Andrezza Braga Soares da Silva Gerson Tavares Pessoa … Francisco das Chagas Araújo Sousa Jacyara de Jesus Rosa Pereira Alves Luiz Bezerra Neto Kassio Vieira Macedo Marcelo Campos Vieira Flávio Ribeiro Alves

Abstract

Introduction

The capuchin monkey is a type of nonhuman primate that has shown great potential for preclinical studies because of its anatomical and physiological similarities to humans.

Objective

To study the indices of myocardial deformation in anesthetized capuchin monkeys using speckle tracking.

Methods

Sixteen animals from the Zoobotanical Park, Teresina, Piauí, Brazil, were used and chemically restrained using a combination of ketamine and midazolam. Echocardiography recordings were obtained in B, M and Doppler modes, and strain and strain rate were measured using speckle tracking.

Results

The variables that showed statistically significant correlation coefficients in relation to weight were LVFWd, LVIDd, LVIDs, E wave, A’RV, MAM and TAPSE. HR showed a positive correlation with the E wave and A wave and a negative correlation with IVRT. FS presented a positive correlation with the E/A wave relationship (r = 0.61). TAPSE showed positive correlations with E’RV and A’RV. The values obtained for circumferential (-18.17 ± 4.68%), radial (47.13 ± 5.24%) and longitudinal (- 26.46 ± 5.15%) strain for the capuchin monkeys were within the normal ranges for males and females.

Conclusion

The present study provides the first reference values for echocardiographic measurements in B, M and Doppler modes for capuchin monkeys anesthetized with ketamine and midazolam. The strain and strain rate values obtained using speckle tracking showed similarities with those obtained in humans, suggesting that this tool has the potential to be exploited in preclinical studies using the capuchin monkey model. (Arq Bras Cardiol: Imagem cardiovasc. 2018;31(1):4-13)

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Brief Communication

Cardiodepressive Effect of Eugenyl Acetate in Rodent Heart

Leisiane Pereira Marques et al. Samuel Santos Beserra Danilo Roman-Campos Antonio Nei Santana Gondim

Introduction

Cardiovascular diseases are a public health problem being among the leading causes of death worldwide. In this perspective, there is a growing interest in the search for new substances with pharmacological actions on the cardiovascular system, including drugs of natural origin.

The Syzygium aromaticum (L.) Merr. & L.M. Perry, popularly known as clove, produces several chemical compounds that have a wide range of biological effects. Eugenol () is the most abundant bioactive compound found in clove essential oil, followed by eugenyl acetate (EA) ().

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IJCS

Editorial

Heart Failure – Pathophysiology and Current Therapeutic Implications

Mariana Vieira de Oliveira Bello et al. Fernando Bacal

The concept of translational medicine involves promoting the rapid transfer of observations made in the areas of research and pathophysiological understanding to the medical practice. This approach is a reality in major Brazilian research centers which link academia and clinical practice.

Heart failure (HF) is a complex syndrome that can manifest itself as heart failure with preserved ejection fraction (HFpEF), acute heart failure, or chronic heart failure with reduced ejection fraction (HFrEF). Here, we will cover the type of HF whose pathophysiology is understood the best and thus has disease-modifying treatments: HFrEF.

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Editorial

At Last, a Sensitive Method to Detect Incipient Systolic Dysfunction!

Carlos Eduardo Suaide Silva

Left ventricular systolic function evaluation has always been one of the main attributions of echocardiography. The degree of ventricular systolic dysfunction is an important predictor of outcome for a large number of diseases, including ischemic heart disease, cardiomyopathy, valvular heart disease, and congenital heart disease. In this area, the ejection fraction has been sovereign for many decades, but despite being a parameter that can, in most cases, inform the real state of global ventricular function, in many situations it may be normal in the presence of evident systolic or diastolic dysfunction.

Known clinical examples are the several cases of heart failure with preserved ejection fraction (HFpEF) or patients with hypertrophic cardiomyopathy, among others. For this reason, an index that can identify early ventricular dysfunction that is not connected with the ejection fraction has been sought for a long time.

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Editorial

Risk Scores for Stroke Prevention in Patients with Non-Valvular Atrial Prevention: Is it Time to Put Parameters of Left Atrial Appendage Morphology and Function Into Clinical Practice?

Angelo A. V. de Paola

Overall, one-third of thromboembolic events originated from the heart. Left atrial appendage (LAA) and its anatomic complexity has been implicated in 90% of cases of thrombus formation and cardioembolic events in patients with non-valvular atrial fibrillation (AF). Risk scores to predict thromboembolism from AF, such as CHADS₂ and CHA₂DS₂VASc are widely used to guide anticoagulation therapy and varies in relation to comorbidities associated with the thrombogenic substrate; however, because of its clinical conception, they did not include atrial anatomy (atrial enlargement), function (flow velocities) and electrophysiology (atrial fibrillation burden). Patients with CHA₂DS₂VASc score ≥ 2 are at intermediate or higher risk (event rate ≥ 2-3%/year) and anticoagulation is recommended. Left atrial variables such as LAA function and morphology, routinely studied by transesophageal echocardiography (TEE), were not considered in these scores.

In 2012, Di Biase et al.; published a retrospective study of 932 patients with AF and computed tomography (CT)/magnetic resonance imaging (MRI) classification of four different types of LAA morphologies: chicken wing, cactus, windsock and cauliflower. Non-chicken wing categories were 4 to 8 times more likely to have had stroke/TIA. Eight additional cross-sectional studies utilizing this classification for LAA morphology in 2,210 patients (6 with CT and 2 with TEE), found a significant association with non-chicken-wing morphology and stroke in 5 series^– and no significant difference in 3 other studies.^–

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Editorial

Global Longitudinal Strain or Measurement of Ejection Fraction: Which Method is Better in Stratifying Patients with Heart Failure?

Filipe Ferrari et al. Willian Roberto Menegazzo

Heart failure (HF) is a complex syndrome that has a poor prognosis and a stigma of high mortality. The current prevalence estimated in the United States is six million cases, with a predicted incidence of another two million patients until 2030. Brazil, specifically, had more than 26 thousand deaths by HF in 2012 and approximately 230 thousand hospitalizations attributed to this disease.

The main HF symptoms include progressive dyspnea, fatigue, exercise intolerance, and signs of volume overload, reducing the functional capacity and quality of life of patients and greatly increasing the risk of morbidity and mortality. In this regard, a peak oxygen consumption (maxVO₂), on average, approximately 50% lower is not uncommon in HF patients when compared to healthy individuals paired by variables such as age and gender. The cardiopulmonary exercise testing (CPET) is a method widely used and trusted in this scenario, with a consistent role in risk stratification of HF patients and various variables obtained with consolidated prognostic value. MaxVO₂ is an important marker of one-year mortality, surpassing ejection fraction and pulmonary capillary wedge pressure, used as Class I to define candidates for heart transplantation. Other prognostic markers obtained from CPET that proved to be important in this population include the measurement of ventilatory efficiency through the VE/VCO₂ slope, regular ventilation, oxygen uptake efficiency slope (OUES), heart rate recovery (HRR) in the first minute, chronotropic competence, and partial pressure of carbon dioxide at rest (PetCO₂).^,

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Original Article

Association between Morphodynamic Variables by Transesophageal Echocardiography and CHA2DS2-Vasc Values

Renata Rejane Linhares et al. Dalmo Antonio Ribeiro Moreira Luciana Braz Peixoto Andresa Paes da Cruz … Luara Piovam Garcia Rodrigo Bellio de Mattos Barretto David Costa de Souza Le Bihan Carlos Eduardo Suaide Silva

Abstract

Background:

In atrial fibrillation (AF), the CHA₂DS₂-VASc score calculates the risk for stroke. Di Biase classified the left atrial appendage (LAA), using magnetic resonance imaging, into 4 morphological types and correlated it with cerebrovascular events. Transesophageal echocardiography (TEE) also evaluates LAA and is a more widespread technique.

Objective:

To evaluate, using TEE, the possibility of characterizing LAA and to analyze its morphological aspects using the CHA₂DS₂VASc score.

Methodology:

A total of 247 patients were divided into three groups considering the CHA₂DS₂-VASc score: Group 1: 0 and 1; Group 2: 2 and 3 and, Group 3: ≥ 4 points. TEE produced the echocardiographic data. LAA was classified into thrombogenic and non-thrombogenic morphologies. In the analysis of statistical tests, a significance level of 5% was adopted.

Results:

The average age was 50 and 16.2% presented AF. In Group 1, we observed normal variables with a lower prevalence of AF (8.7%, p < 0.001). In group 2, spontaneous contrast was detected in 26.7%, (p < 0.001), thrombus in 6.7% (p = 0.079) and flow velocity in LAA < 0.4 m/s in 22.7% (p < 0.001) of the cases. Group 3 presented the highest percentages of AF (31.8%, p < 0.001), stroke/TIA (77.3%, p < 0.001), EF < 55% (18.2%, p = 0.010) and higher prevalence of thrombogenic type LAA (72.7%, p = 0.014). A higher occurrence of stroke/TIA was observed in patients with thrombogenic LAA (25.2%) compared to the non-thrombogenic group (11.2%), (p = 0.005).

Conclusions:

The thrombogenic morphology of LAA identified in TEE presented a higher risk of stroke regardless of the CHA₂DS₂VASc score. Patients with higher scores had greater abnormalities in echocardiographic variables.

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Brief Communication

Influence of Aerobic Training on The Mechanics of Ventricular Contraction After Acute Myocardial Infarction: A Pilot Study

Giovani Luiz De Santi et al. Henrique Turin Moreira Eduardo Elias Vieira de Carvalho Júlio César Crescêncio … André Schmidt José Antônio Marin-Neto Lourenço Gallo-Júnior

Abstract

The study of myocardial contractility, based on the new anatomical concepts that govern cardiac mechanics, represents a promising strategy of analysis of myocardial adaptations related to physical training in the context of post-infarction.

We investigated the influence of aerobic training on physical capacity and on the evaluation parameters of left ventricular contraction mechanics in patients with myocardial infarction.

Thirty-one patients (55.1 ± 8.9 years) who had myocardial infarction in the anterior wall were prospectively investigated in three groups: interval training group (ITG) (n = 10), moderate training group (MTG) n = 10) and control group (CG) (n = 10). Before and after 12 weeks of clinical follow-up, patients underwent cardiopulmonary exercise testing and cardiac magnetic resonance imaging. The trained groups performed supervised aerobic training on treadmill, in two different intensities.

A statistically significant increase in peak oxygen uptake (VO₂) was observed in the ITG (19.2 ± 5.1 at 21.9 ± 5.6 ml/kg/min, p < 0.01) and in the MTG 18.8 ± 3.7 to 21.6 ± 4.5 ml/kg/min, p < 0.01). The GC did not present a statistically significant change in peak VO₂. A statistically significant increase in radial strain (STRAD) was observed in the CG: basal STRAD (57.4 ± 16.6 to 84.1 ± 30.9%, p < 0.05), medial STRAD (57.8 ± 27, 9 to 74.3 ± 36.1%, p < 0.05) and apical STRAD (38.2 ± 26.0 to 52.4 ± 29.8%, p < 0.01). The trained groups did not present a statistically significant change of the radial strain.

The present study points to a potential clinical application of the parameters of ventricular contraction mechanics analysis, especially radial strain, to discriminate post-infarction myocardial adaptations between patients submitted or not to aerobic training programs.

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Original Article

Moderate Continuous Aerobic Exercise Training Improves Cardiomyocyte Contractility in Β1 Adrenergic Receptor Knockout Mice

Aurora Corrêa Rodrigues et al. Antônio José Natali Daise Nunes Queiroz da Cunha Alexandre Jayme Lopes Dantas Costa … Anselmo Gomes de Moura Miguel Araújo Carneiro-Júnior Leonardo Bonato Félix Patrícia Chakur Brum Thales Nicolau Prímola-Gomes

Abstract

Background:

The lack of cardiac β₁-adrenergic receptors (β₁-AR) negatively affects the regulation of both cardiac inotropy and lusitropy, leading, in the long term, to heart failure (HF). Moderate-intensity aerobic exercise (MCAE) is recommended as an adjunctive therapy for patients with HF.

Objective:

We tested the effects of MCAE on the contractile properties of left ventricular (LV) myocytes from β₁ adrenergic receptor knockout (β₁ARKO) mice.

Methods:

Four- to five-month-old male wild type (WT) and β₁ARKO mice were divided into groups: WT control (WTc) and trained (WTt); and β₁ARKO control (β₁ARKOc) and trained (β₁ARKOt). Animals from trained groups were submitted to a MCAE regimen (60 min/day; 60% of maximal speed, 5 days/week) on a treadmill, for 8 weeks. P ≤ 0.05 was considered significant in all comparisons.

Results:

The β₁ARKO and exercised mice exhibited a higher (p < 0.05) running capacity than WT and sedentary ones, respectively. The β₁ARKO mice showed higher body (BW), heart (HW) and left ventricle (LVW) weights, as well as the HW/BW and LVW/BW than WT mice. However, the MCAE did not affect these parameters. Left ventricular myocytes from β₁ARKO mice showed increased (p < 0.05) amplitude and velocities of contraction and relaxation than those from WT. In addition, MCAE increased (p < 0.05) amplitude and velocities of contraction and relaxation in β₁ARKO mice.

Conclusion:

MCAE improves myocyte contractility in the left ventricle of β₁ARKO mice. This is evidence to support the therapeutic value of this type of exercise training in the treatment of heart diseases involving β₁-AR desensitization or reduction.

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Original Article

Effect Of Resistance Training On Myocardial Contractility In Vitro After Sleep Deprivation

Sara Quaglia de Campos Giampá et al. Marcos Mônico-Neto Helton de Sá Souza Marco Túlio de Mello … Sergio Tufik Leslie Andrews Portes Andrey Jorge Serra Paulo José Ferreira Tucci Hanna Karen Moreira Antunes

Abstract

Background:

Resistance training promotes cardiovascular health benefits that may affected by sleep deprivation.

Objective:

To evaluate the effect of high-intensity resistance training on myocardial contractility in rats subsequently subjected to paradoxical sleep deprivation.

Methods:

Forty male Wistar rats were distributed into control group (CTRL), resistance training (REST), 96-hour paradoxical sleep deprivation (PSD96) and resistance training followed by 96-hour paradoxical sleep deprivation (REST/PSD96). The animals underwent high-intensity resistance training for 8 weeks, 5x/week. Twenty-four hours after the last training session, the PSD96 and REST/PSD96 groups were submitted to paradoxical sleep deprivation, which was followed by the in vitro study of isolated papillary muscle contractile mechanics.

Results:

In comparison with the CTRL group, a lower papillary muscle length and increased cross sectional area were found in PSD96 and RETS/PSD96, which were associated with decreased temporal parameters of contraction force and relaxation. Decreased resting tension and slowing of relaxation time were found in the PSD96 group only. This effect was attenuated by previous resistance training.

Conclusion:

Resistance training partially prevented contractile changes induced by PSD, minimizing the slowing in relaxation time. Thus, high-intensity exercise seems to not fully protect the cardiac tissue from PSD-induced effects.

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Original Article

Functional Effects of Hyperthyroidism on Cardiac Papillary Muscle in Rats

Fabricio Furtado Vieira et al. Robson Ruiz Olivoto Priscyla Oliveira da Silva Julio Cesar Francisco Rosalvo Tadeu Hochmuller Fogaça

Abstract

Background:

Hyperthyroidism is currently recognized to affect the cardiovascular system, leading to a series of molecular and functional changes. However, little is known about the functional influence of hyperthyroidism in the regulation of cytoplasmic calcium and on the sodium/calcium exchanger (NCX) in the cardiac muscle.

Objectives:

To evaluate the functional changes in papillary muscles isolated from animals with induced hyperthyroidism.

Methods:

We divided 36 Wistar rats into a group of controls and another of animals with hyperthyroidism induced by intraperitoneal T3 injection. We measured in the animals’ papillary muscles the maximum contraction force, speed of contraction (+df/dt) and relaxation (-df/dt), contraction and relaxation time, contraction force at different concentrations of extracellular sodium, post-rest potentiation (PRP), and contraction force induced by caffeine.

Results:

In hyperthyroid animals, we observed decreased PRP at all rest times (p < 0.05), increased +df/dt and -df/dt (p < 0.001), low positive inotropic response to decreased concentration of extracellular sodium (p < 0.001), reduction of the maximum force in caffeine-induced contraction (p < 0.003), and decreased total contraction time (p < 0.001). The maximal contraction force did not differ significantly between groups (p = 0.973).

Conclusion:

We hypothesize that the changes observed are likely due to a decrease in calcium content in the sarcoplasmic reticulum, caused by calcium leakage, decreased expression of NCX, and increased expression of a-MHC and SERCA2.

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Original Article

Effect of Fetal Hypothyroidism on Cardiac Myosin Heavy Chain Expression in Male Rats

Nasibeh Yousefzadeh et al. Sajad Jeddi Mohammad Reza Alipour

Abstract

Background:

Thyroid hormone deficiency during fetal life could affect the cardiac function in later life. The mechanism underlying this action in fetal hypothyroidism (FH) in rats has not been elucidated thus far.

Objective:

The aim of this study is to evaluation the effect of FH on cardiac function in male rats and to determine the contribution of α-myosin heavy chain (MHC) and β-MHC isoforms.

Methods:

Six pregnant female rats were randomly divided into two groups: The hypothyroid group received water containing 6-propyl-2-thiouracil during gestation and the controls consumed tap water. The offspring of the rats were tested in adulthood. Hearts from the FH and control rats were isolated and perfused with langendroff setup for measuring hemodynamic parameters; also, the heart mRNA expressions of α- MHC and β-MHC were measured by qPCR.

Results:

Baseline LVDP (74.0 ± 3.1 vs. 92.5 ± 3.2 mmHg, p < 0.05) and heart rate (217 ± 11 vs. 273 ± 6 beat/min, p < 0.05) were lower in the FH rats than controls. Also, these results showed the same significance in ±dp/dt. In the FH rats, β-MHC expression was higher (201%) and α- MHC expression was lower (47%) than control.

Conclusion:

Thyroid hormone deficiency during fetal life could attenuate normal cardiac functions in adult rats, an effect at least in part due to the increased expression of β-MHC to α- MHC ratio in the heart.

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Original Article

Predictors of Arrhythmic Events Detected by Implantable Loop Recorders in Renal Transplant Candidates

Rodrigo Tavares Silva et al. Martino Martinelli Filho Giselle de Lima Peixoto José Jayme Galvão de Lima … Sérgio Freitas de Siqueira Roberto Costa Luís Henrique Wolff Gowdak Flávio Jota de Paula Roberto Kalil Filho José Antônio Franchini Ramires

Abstract

Background:

The recording of arrhythmic events (AE) in renal transplant candidates (RTCs) undergoing dialysis is limited by conventional electrocardiography. However, continuous cardiac rhythm monitoring seems to be more appropriate due to automatic detection of arrhythmia, but this method has not been used.

Objective:

We aimed to investigate the incidence and predictors of AE in RTCs using an implantable loop recorder (ILR).

Methods:

A prospective observational study conducted from June 2009 to January 2011 included 100 consecutive ambulatory RTCs who underwent ILR and were followed-up for at least 1 year. Multivariate logistic regression was applied to define predictors of AE.

Results:

During a mean follow-up of 424 ± 127 days, AE could be detected in 98% of patients, and 92% had more than one type of arrhythmia, with most considered potentially not serious. Sustained atrial tachycardia and atrial fibrillation occurred in 7% and 13% of patients, respectively, and bradyarrhythmia and non-sustained or sustained ventricular tachycardia (VT) occurred in 25% and 57%, respectively. There were 18 deaths, of which 7 were sudden cardiac events: 3 bradyarrhythmias, 1 ventricular fibrillation, 1 myocardial infarction, and 2 undetermined. The presence of a long QTc (odds ratio [OR] = 7.28; 95% confidence interval [CI], 2.01–26.35; p = 0.002), and the duration of the PR interval (OR = 1.05; 95% CI, 1.02–1.08; p < 0.001) were independently associated with bradyarrhythmias. Left ventricular dilatation (LVD) was independently associated with non-sustained VT (OR = 2.83; 95% CI, 1.01–7.96; p = 0.041).

Conclusions:

In medium-term follow-up of RTCs, ILR helped detect a high incidence of AE, most of which did not have clinical relevance. The PR interval and presence of long QTc were predictive of bradyarrhythmias, whereas LVD was predictive of non-sustained VT.

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Ablation of Premature Ventricular Contraction with the Help of a Notch

Firat Özcan et al. Serkan Topaloğ lu Osman Turak Serkan Çay Dursun Aras

A 43-year-old male patient presented with a complaint of palpitation. Electrocardiography revealed premature ventricular contraction (PVC) that appeared to be originating from the left ventricular outflow tract. Tall positive R waves were observed in leads II, III, and aVF, and the R transition was observed at V2 in precordial leads. A notch was realized on the downward deflection of QS, which was only at lead V1. () This finding indicates that the region between the right and left coronary commissures is the origin of VPS. In addition, 24-h Holter monitoring revealed 32000 PVCs. Therefore, an electrophysiology study was planned. During the procedure, the catheter was moved between the right coronary and left coronary commissures, and the ablation catheter was placed at the ventricular side of the commissures where the earliest signal recorded was at 40 ms. At this site, pacing produced 12/12 morphology with PVC. In addition, at this site, we demonstrated a deflection prior to the intracardiac ventricular electrogram of PVCs corresponding to the notch. This deflection was after the intracardiac ventricular electrogram during sinus beats (). Ablation was performed at 20 watt 45 degrees, and it terminated all PVCs at this site.

PVCs can be very disturbing in some patients, and medical treatment may be tried. Long-term impacts of PVC may be deleterious for systolic ventricular function. Ablation of culprit source of PVC is an effective treatment and may improve systolic function of the left ventricle. Our patient was on a long-term medical treatment that failed to terminate PVCs. We preferred ablation for treatment. In this case, we would like to mention that ECG is an important, simple, cheap, and widely available tool that can be used for localization.

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Artigo Original

Left ventricular synchrony and function in pediatric patients with definitive pacemakers

Michel Cabrera Ortega et al. Adel Eladio Gonzales Morejón Giselle Serrano Ricardo

BACKGROUND: Chronic right ventricular pacing (RVP) induces a dyssynchronous contraction pattern,producing interventricular and intraventricular asynchrony. Many studies have shown the relationship of RVP with impaired left ventricular (LV) form and function. OBJECTIVE: The aim of this study was to evaluate LV synchrony and function in pediatric patients receiving RVP in comparison with those receiving LV pacing (LVP). METHODS:LV systolic and diastolic function and synchrony were evaluated in 80 pediatric patients with either nonsurgical or postsurgical complete atrioventricular block, with pacing from either the RV endocardium (n = 40) or the LV epicardium (n = 40). Echocardiographic data obtained before pacemaker implantation, immediately after it, and at the end of a mean follow-up of 6.8 years were analyzed. RESULTS: LV diastolic function did not change in any patient during follow-up. LV systolic function was preserved in patients with LVP. However, in children with RVP the shortening fraction and ejection fraction decreased from medians of 41% ± 2.6% and 70% ± 6.9% before implantation to 32% ± 4.2% and 64% ± 2.5% (p < 0.0001 and p < 0.0001), respectively, at final follow-up. Interventricular mechanical delay was significantly larger with RVP (66 ± 13 ms) than with LVP (20 ± 8 ms). Similarly, the following parameters were significantly different in the two groups: LV mechanical delay (RVP: 69 ± 6 ms, LVP: 30 ± 11 ms, p < 0.0001); septal to lateral wall motion delay (RVP: 75 ± 19 ms, LVP: 42 ± 10 ms, p < 0.0001); and, septal to posterior wall motion delay (RVP: 127 ± 33 ms, LVP: 58 ± 17 ms, p < 0.0001). CONCLUSION: Compared with RV endocardium, LV epicardium is an optimal site for pacing to preserve cardiac synchrony and function.

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Artigo Original

Morphology and contractility in cardiomyocytes of rats with low exercise performance

Judson Fonseca Quintão Júnior et al. Antônio José Natali Miguel Araújo Carneiro Júnior Cynthia Aparecida de Castro … Lucas Rios Drummond Victor Neiva Lavorato Leonardo Bonato Felix Jader dos Santos Cruz Thales Nicolau Prímola-Gomes

BACKGROUND: Aerobic capacity is essential to physical performance, and low aerobic capacity is related to the triggering of various cardiovascular diseases. OBJECTIVE: To compare the morphology and contractility of isolated rat cardiomyocytes with low performance and standard performance for exercise. METHODS: Wistar rats with 10 weeks of age underwent a protocol of treadmill running to fatigue, and were divided into two groups: Low Performance (LP) and Standard Performance (SP). Then, the animals were sacrificed, the heart was quickly removed and, by means of enzymatic dissociation, left ventricular cardiomyocytes were isolated. The cell and sarcomeres length and width of cardiomyocytes were measured using an edge detection system. The isolated cardiomyocytes were electrically stimulated at 1 and 3 Hz and cell contraction was measured by registering the change of their length. RESULTS: The cell length was shorter in the LP group (157.2 1.3µm; p < 0.05) compared to SP (161.4 1.3µm), and the same result was observed for the volume of cardiomyocytes (LP, 25.5 0.4. vs. SP, 26.8 ± 0.4 pL; p < 0.05). The time to peak contraction (LP, 116 1 vs. SP 111 2ms) and total relaxation (LP, 143 3 vs. SP 232 3ms) were higher in the LP group. CONCLUSION: We conclude that left ventricular myocytes of animals with low performance for exercise are smaller than animals with standard performance. In addition to that, they present losses in contractile capacity.

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Case Report

Two-dimensional strain in Takotsubo cardiomyopathy

Carlos Bellini G. Gomes et al. Gustavo J. Veras

This report presents the late follow-up of a case of Takotsubo cardiomyopathy with good clinical outcome and improved left ventricular global systolic function. However, there was persistence of significant regional longitudinal systolic dysfunction evaluated using a new echocardiographic technique (speckle tracking), with corresponding measures of strain (S) and strain rate (SR). We emphasize the importance of this new method to monitoring this cardiomyopathy, since it identifies patients with persistent systolic dysfunction who will possibly benefit from maintenance of clinical therapy

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Ischemic preconditioning influence ventricular function in off-pump revascularization surgery

José Ernesto Succi et al. Luís Roberto Gerola Guilherme Menezes Succi Renata A.C.F. de Almeida … Leonardo Sérgio Rocha Novais Bruno Rocha

BACKGROUND: Ischemic preconditioning is a method that prepares and protects cells to tolerate a long period of ischemia with the least possible injury. OBJECTIVES: Evaluate the influence of ischemic preconditioning over left ventricular function during off-pump myocardial revascularization. METHOD: Forty patients with clinical indication for off-pump myocardial revascularization were randomized in two groups, with or without ischemic preconditioning. Ischemic preconditioning was carried out by performing coronary occlusion for two minutes and releasing blood flow for one minute; two cycles were performed. Left ventricular contractility was evaluated through transesophageal Doppler by measuring blood flow acceleration in the descending aorta – Hemosonic 100. The acceleration measurements were performed at the start of the surgery, after heart positioning and five and ten minutes after coronary occlusion. RESULTS: There was no significant difference in left ventricular contractility between the two groups. At the beginning of the procedure flow acceleration was 9.37 ± 2.9m/s² in the preconditioning group and 12.5 ± 3.1 m/s² in no-preconditioning group (p = 0.23); after positioning of heart, it was 8.47 ± 3.3 and 8.31 ± 3.6 m/s² (p = 0.96); after five minutes – 8.7 ± 4.1 and 7.94 ± 2.9 m/s² (p = 0.80); and after ten minutes – 9.2 ± 4.5 and 7.98 ± 3.4 m/s² (p = 0.71). However, contractility evolution was different throughout time in each group. The preconditioning group maintained left ventricular contractility during the entire procedure, since the beginning (0.52), while the group without ischemic preconditioning presented reduction in left ventricular contractility (p = 0.0034). CONCLUSION: Ischemic preconditioning prevented the decrease in left ventricular contractility during off-pump myocardial revascularization surgery.

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Case Report

Prinzmetal's angina

Eduardo Contreras Zuniga et al. Juan Esteban Gomez Mesa Sandra Ximena Zuluaga Martinez Vanesa Ocampo Cristian Andres Urrea

This syndrome is due to focal spasm of an epicardial coronary artery, leading to severe myocardial ischemia. Although it is frequently thought that the spasm occurs in arteries without stenosis, many Prinzmetal patients have spasm adjacent to atheromatous plaques. The exact cause of the spasm has not been well defined, but it may be related to the hypercontractility of the vascular smooth muscle due to vasoconstrictor mitogens, leukotrienes, or serotonin. In some patients, it is a manifestation of a vasospastic disorder and it is associated with migraine, Raynaud’s phenomenon, or aspirin-induced asthma. We present a case associated with transient ST-segment depression.

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