Ryanodine receptor phosphorylation in human heart failure

Heart failure is a complex disorder, characterized by activation of the sympathetic nervous system, leading to dysregulated Ca2+ homeostasis in cardiac myocytes and tissue remodeling. In a variety of diseases, cardiac malfunction is associated with aberrant fluxes of Ca2+ across both the surface membrane and the internal Ca2+ store, the sarcoplasmic reticulum (SR). One prominent hypothesis residues is that in heart failure, the activity of the ryanodine receptor (RyR2) Ca2+ release channel in the SR is increased due to excess phosphorylation and that this contributes to excess SR Ca2+ leak in diastole, reduced SR Ca2+ load and decreased contractility (Huke & Bers, 2008). There is controversy over which serine residues in RyR2 are hyperphosphorylated in animal models of heart failure and whether this is via the CaMKII or the PKA-linked signaling pathway. S2808, S2814 and S2030 in RyR2 have been variously claimed to be hyperphosphorylated. Our aim was to examine the degree of phosphorylation of these residues in RyR2 from failing human hearts. The use of human tissue was approved by the Human Research Ethics Committee, The Prince Charles Hospital, EC28114. Left ventricular tissue samples were obtained from an explanted heart of a patient with endstage heart failure (Emery Dreifuss Muscular Dystrophy with cardiomyopathy) and non-failing tissue was from a patient with cystic fibrosis undergoing heart-lung transplantation with no history of heart disease. SR vesicles were prepared as described by Laver et al. (1995) and examined with SDS-Page and Western Blot. Transferred proteins were probed with antibodies to detect total protein phosphorylation, phosphorylation of RyR2 serine residues S2808, S2814, S2030 and for the key proteins calsequestrin, triadin, junctin and FKBP12.6. To avoid membrane stripping artifact, each membrane was exposed to one phosphorylation-specific antibody and signal densities quantified using Bio-Rad Quantity One software. We found no distinguishable difference between failing and healthy hearts in the protein expression levels of RyR2, triadin, junctin or calsequestrin. We found an expected upregulation of total RyR2 phosphorylation in the failing heart sample, compared to a matched amount of RyR2 (quantified using densiometry) in healthy heart. Probing with antibodies detecting only the phosphorylated form of the specific RyR2 residues showed that the increase in total RyR2 phosphorylation in the failing heart was due to hyperphosphorylation of S2808 and S2814. We found that S2030 phosphorylation levels were unchanged in human heart failure. Interestingly, we found that S2030 has a basal level of phosphorylation in the healthy human heart, different from the absence of basal phosphorylation recently reported in rodent heart (Huke & Bers, 2008). Finally, preliminary results indicate that less FKBP 12.6 is associated with RyR2 in the failing heart, possibly as a consequence of PKA activation. In conclusion, residues S2808 and S2814 are hyperphosphorylated in human heart failure, presumably due to upregulation of the CaMKII and/or PKA signaling pathway as a result of chronic activation of the sympathetic nervous system. Such changes in RyR2 phosphorylation are believed to contribute to the leaky RyR2 phenotype associated with heart failure, which increases the incidence of arrhythmia and contributes to the severely impaired contractile performance of the failing heart. Huke S & Bers DM. (2008). Ryanodine receptor phosphorylation at serine 2030, 2808 and 2814 in rat cardiomyocytes. Biochemical and Biophysical Research Communications 376, 80-85. Laver DR, Roden LD, Ahern GP, Eager KR, Junankar PR & Dulhunty AF. (1995). Cytoplasmic Ca2+ inhibits the ryanodine receptor from cardiac muscle. Journal of Membrane Biology 147, 7-22. Proceedings

Letter: Brain natriuretic peptide is a potentially useful screening tool for the detection of cardiovascular disease in patients with rheumatoid arthritis

Patients with rheumatoid arthritis (RA) have a significantly higher risk of coronary heart disease, despite being less likely to report symptoms of angina, and are more likely to experience unrecognised myocardial infarction and sudden cardiac death than non-RA controls.1 Furthermore, left ventricular diastolic dysfunction has been described in up to 40% of patients with RA.2...

Genome-wide association study identifies eight loci associated with blood pressure

Elevated blood pressure is a common, heritable cause of cardiovascular disease worldwide. To date, identification of common genetic variants influencing blood pressure has proven challenging. We tested 2.5 million genotyped and imputed SNPs for association with systolic and diastolic blood pressure in 34,433 subjects of European ancestry from the Global BPgen consortium and followed up findings with direct genotyping (N 71,225 European ancestry, N 12,889 Indian Asian ancestry) and in silico comparison (CHARGE consortium, N = 29,136). We identified association between systolic or diastolic blood pressure and common variants in eight regions near the CYP17A1 (P = 7 × 10 24), CYP1A2 (P = 1 × 10 23), FGF5 (P = 1 × 10 21), SH2B3 (P = 3 × 10 18), MTHFR (P = 2 × 10 13), c10orf107 (P = 1 × 10 9), ZNF652 (P = 5 × 10 9) and PLCD3 (P = 1 × 10 8) genes. All variants associated with continuous blood pressure were associated with dichotomous hypertension. These associations between common variants and blood pressure and hypertension offer mechanistic insights into the regulation of blood pressure and may point to novel targets for interventions to prevent cardiovascular disease.

The mechanical triggers of plaque rupture: Shear stress vs pressure gradient

The aim of this study was to evaluate the mechanical triggers that may cause plaque rupture. Wall shear stress (WSS) and pressure gradient are the direct mechanical forces acting on the plaque in a stenotic artery. Their influence on plaque stability is thought to be controversial. This study used a physiologically realistic, pulsatile flow, two-dimensional, cine phase-contrast MRI sequence in a patient with a 70% carotid stenosis. Instead of considering the full patient-specific carotid bifurcation derived from MRI, only the plaque region has been modelled by means of the idealised flow model. WSS reached a local maximum just distal to the stenosis followed by a negative local minimum. A pressure drop across the stenosis was found which varied significantly during systole and diastole. The ratio of the relative importance of WSS and pressure was assessed and was found to be less than 0.07% for all time phases, even at the throat of the stenosis. In conclusion, although the local high WSS at the stenosis may damage the endothelium and fissure plaque, the magnitude of WSS is small compared with the overall loading on plaque. Therefore, pressure may be the main mechanical trigger for plaque rupture and risk stratification using stress analysis of plaque stability may only need to consider the pressure effect.

In vivo non-invasive high resolution MR-based method for the determination of the elastic modulus of arterial vessels

The mechanical properties of arterial walls have long been recognized to play an essential role in the development and progression of cardiovascular disease (CVD). Early detection of variations in the elastic modulus of arteries would help in monitoring patients at high cardiovascular risk stratifying them according to risk. An in vivo, non-invasive, high resolution MR-phase-contrast based method for the estimation of the time-dependent elastic modulus of healthy arteries was developed, validated in vitro by means of a thin walled silicon rubber tube integrated into an existing MR-compatible flow simulator and used on healthy volunteers. A comparison of the elastic modulus of the silicon tube measured from the MRI-based technique with direct measurements confirmed the method's capability. The repeatability of the method was assessed. Viscoelastic and inertial effects characterizing the dynamic response of arteries in vivo emerged from the comparison of the pressure waveform and the area variation curve over a period. For all the volunteers who took part in the study the elastic modulus was found to be in the range 50-250 kPa, to increase during the rising part of the cycle, and to decrease with decreasing pressure during the downstroke of systole and subsequent diastole.

Sydämen hypertrofian ja kroonisen vajaatoiminnan farmakologinen hoito

Sydämen krooninen vajaatoiminta on merkittävä maailmanlaajuinen ongelma. Se on erilaisten sydän- ja verisuonisairauksien aiheuttama monimuotoinen oireyhtymä. Sydämen vasemman kammion hypertrofia eli sydämen seinämien paksuuntuminen on yksi keskeinen tekijä, joka voi olla sydämen vajaatoiminnan taustalla. Kohonnut verenpaine on yleisin syy, joka johtaa sydänlihaksen paksuuntumiseen. Tämä johtaa sydämen pumppaustoiminnan häiriintymiseen, erilaisten neurohormonaalisten mekanismien aktivaatioon ja edelleen sydämen vajaatoimintaan. Sydämen vajaatoiminnan neurohormonaalisista mekanismeista tärkeimmät ovat reniini-angiotensiini-aldosteroni-järjestelmän ja sympaattisen hermoston aktivaatio, sydämen rakenteiden uudelleenmuovautuminen, sydänlihassolujen apoptoosi ja systeeminen tulehdustila. Sydämen hypertrofiaa ja sen syntymistä pyritään estämään kohonneen verenpaineen lääkehoidolla. Reniini-angiotensiini-aldosteronijärjestelmällä on keskeinen merkitys sydämen vajaatoiminnassa. Sydämen vajaatoiminnan ennusteeseen vaikuttavista lääkeaineista angiotensiinikonvertasin estäjät (ACEestäjät) ovat säilyttäneet johtoasemansa jo vuosikymmenten ajan. Angiotensiinireseptoreiden salpaajien (AT1-salpaajien) odotettiin syrjäyttävän ACE-estäjät sydämen vajaatoiminnan hoidossa, mutta toistaiseksi niitä pidetään vain vaihtoehtoisina lääkkeinä. Sympaattisen hermoston aktivaatiota vähentävät β-salpaajat ovat vakiinnuttaneet asemansa toiseksi tärkeimpänä lääkeryhmänä. Diureetit ovat paljon käytetty lääkeaineryhmä sydämen vajaatoiminnan hoidossa, mutta niistä ainoastaan aldosteroniantagonisteilla on tutkitusti ennustetta parantavaa vaikutusta. Kroonisen vajaatoiminnan hoidossa käytetään edelleen myös digoksiinia. Tulevaisuudessa sydämen vajaatoiminnan ennusteeseen vaikuttavia lääkeaineita voivat olla reniinin estäjät, neutraaliendopeptidaasin estäjät, vasopressiinin antagonistit tai inflammatroisiin sytokiineihin vaikuttavat molekyylit. Erikoistyön kokeellisessa osiossa tarkoituksena oli tutkia sydämen hypertrofian kehittymistä vatsa-aortta kuristetuilla rotilla ja kalsiumherkistäjä levosimendaanin sekä AT1-salpaaja valsartaanin vaikutuksia hypertrofian kehittymiseen. Kokeellisessa osiossa arvioitiin myös sydämen hypertrofian ja vajaatoiminnan jyrsijämallina käytetyn vatsa-aortan kuristuksen (koarktaation) toimivuutta ja vaikutuksia ultraäänen avulla määritettyihin kardiovaskulaarisiin parametreihin. Vatsa-aortta kuristettiin munuaisvaltimoiden yläpuolelta. Kuristus saa aikaan verenpaineen kohoamisen ja sydämen työtaakan lisääntymisen. Pitkittyessään tila johtaa sydänlihaksen hypertrofiaan ja vajaatoimintaan. 64 eläintä jaettiin ryhmiin, siten että jokaiseen ryhmään tuli kahdeksan eläintä. Ryhmistä kolmelle annettiin lääkeaineena levosimendaania kolmella eri päiväannoksella (0,01 mg/kg; 0,10 mg/kg; 1,00 mg/kg) ja kolmelle valsartaania kolmella eri päiväannoksella (0,10 mg/kg; 1,00 mg/kg; 10,00 mg/kg) juomaveden mukana. Lääkitys aloitettiin leikkauksen jälkeen ja jatkettiin kahdeksan viikon ajan. Kardiovaskulaariset parametrit, kuten isovolumetrinen relaksaatioaika (IVRT), vasemman kammion läpimitta systolessa ja diastolessa sekä seinämäpaksuudet, ejektiofraktio (EF), supistuvuusosuus (FS), minuuttitilavuus (CO) ja iskutilavuus (SV) määritettiin kahdeksan viikon kuluttua leikkauksesta ultraäänitutkimuksen avulla. Lisäksi määritettiin eläinten sydämen paino suhteessa ruumiin painoon. Tuloksia verrattiin ilman lääkehoitoa olleeseen koarktaatioryhmään. Eläinmallin toimivuutta arvioitiin vertaamalla koarktaatioryhmän tuloksia sham-operoidun ryhmän tuloksiin. Levosimendaanilla havaittiin työssä sydämen systolista toimintaa parantava vaikutus. Tämä näkyi tendenssinä parantaa ejektiofraktioita ja vasemman kammion supistuvuusosuuksia. Sydämen diastoliseen toimintaan ei kummallakaan lääkeaineella ollut merkittävää vaikutusta. Diastolista toimintaa arvioitiin isovolumetrisen relaksaatioajan muutoksilla. Sydämen hypertrofian kehittymiseen ei kummallakaan lääkeaineella ollut merkittävää vaikutusta. Eläinmallin todettiin mallintavan hyvin sydämen hypetrofiaa ihmisellä, mutta ei niinkään sydämen vajaatoimintaa.

Análise da função diastólica em mulheres medicadas com antraciclínicos no tratamento do câncer de mama

O Câncer de mama é um dos problemas de saúde pública mais importantes em nosso país. São estimados, para 2010, 49.400 novos casos de câncer de mama no Brasil, com um risco estimado de 51 casos a cada 100 mil mulheres. A estratégia de tratamento das pacientes com tumores de mama pode passar pelo uso de quimioterapia. A doxorrubicina é uma das drogas mais ativas para o câncer de mama, pertencendo ao grupo das antraciclinas. A família das antraciclinas apresenta como efeito colateral dano ao miocárdio que pode chegar a 36% dependendo da dose utilizada. O efeito sobre o miocárdio costuma ocorrer mais comumente durante ou logo após o último ciclo de quimioterapia podendo, entretanto ocorrer após vários anos do último ciclo de quimioterapia. O objetivo deste estudo foi analisar as alterações da função diastólica ventricular esquerda em mulheres usuárias de antraciclínicos no tratamento do câncer de mama. Realizamos um estudo prospectivo, em uma coorte de mulheres entre 18 e 69 anos, com câncer de mama e indicação de quimioterapia com doxorrubicina. Acompanhamos por período não inferior a 18 meses um grupo de 38 pacientes que cumpriram os critérios de elegibilidade. A dose de doxorrubicina utilizada variou de 50 a 60 mg/m/SC. Todos os pacientes são do sexo feminino, e portadores do tipo histológico carcinoma ductal infiltrante. Duas pacientes faleceram durante o estudo, de causa não cardíaca. Em nossa avaliação, ao final do estudo observamos que os parâmetros: dimensões do átrio esquerdo, dimensões do ventrículo esquerdo na diástole, dimensões do ventrículo esquerdo na sístole, velocidade da onda E, relação da fase de enchimento rápido pela sístole atrial, velocidade diastólica tardia do anel mitral, velocidade diastólica precoce do anel mitral, tempo de desaceleração e a relação da velocidade de enchimento rápido precoce de VE pela velocidade diastólica precoce do anel mitral demonstraram serem parâmetros de grande utilidade para seguimento da lesão cardíaca por antraciclínicos. Já o que não ocorreu com: a fração de encurtamento, fração de ejeção, volume do AE, volume do AE corrigido pela superfície corporal, velocidade diastólica tardia, tempo de relaxamento isovolumétrico, velocidade sistólica do anel mitral, que não apresentaram alterações significativas neste estudo. A análise da função diastólica utilizando o ecocardiograma mostrou ser um método eficaz, que em conjunto com a da função sistólica possibilita detectar precocemente o possível dano miocárdico, oriundo ao uso da quimioterapia com antraciclínicos, favorecendo uma intervenção terapêutica precoce e adequada.

Physically-Based Combinations of Views: Representing Rigid and Nonrigid Motion

Nonrigid motion can be described as morphing or blending between extremal shapes, e.g., heart motion can be described as transitioning between the systole and diastole states. Using physically-based modeling techniques, shape similarity can be measured in terms of forces and strain. This provides a physically-based coordinate system in which motion is characterized in terms of physical similarity to a set of extremal shapes. Having such a low-dimensional characterization of nonrigid motion allows for the recognition and the comparison of different types of nonrigid motion.

Intracardiac acoustic radiation force impulse imaging: a novel imaging method for intraprocedural evaluation of radiofrequency ablation lesions.

BACKGROUND: Arrhythmia recurrence after cardiac radiofrequency ablation (RFA) for atrial fibrillation has been linked to conduction through discontinuous lesion lines. Intraprocedural visualization and corrective ablation of lesion line discontinuities could decrease postprocedure atrial fibrillation recurrence. Intracardiac acoustic radiation force impulse (ARFI) imaging is a new imaging technique that visualizes RFA lesions by mapping the relative elasticity contrast between compliant-unablated and stiff RFA-treated myocardium. OBJECTIVE: To determine whether intraprocedure ARFI images can identify RFA-treated myocardium in vivo. METHODS: In 8 canines, an electroanatomical mapping-guided intracardiac echo catheter was used to acquire 2-dimensional ARFI images along right atrial ablation lines before and after RFA. ARFI images were acquired during diastole with the myocardium positioned at the ARFI focus (1.5 cm) and parallel to the intracardiac echo transducer for maximal and uniform energy delivery to the tissue. Three reviewers categorized each ARFI image as depicting no lesion, noncontiguous lesion, or contiguous lesion. For comparison, 3 separate reviewers confirmed RFA lesion presence and contiguity on the basis of functional conduction block at the imaging plane location on electroanatomical activation maps. RESULTS: Ten percent of ARFI images were discarded because of motion artifacts. Reviewers of the ARFI images detected RFA-treated sites with high sensitivity (95.7%) and specificity (91.5%). Reviewer identification of contiguous lesions had 75.3% specificity and 47.1% sensitivity. CONCLUSIONS: Intracardiac ARFI imaging was successful in identifying endocardial RFA treatment when specific imaging conditions were maintained. Further advances in ARFI imaging technology would facilitate a wider range of imaging opportunities for clinical lesion evaluation.

Determinants of left ventricular mass as measured by Doppler echocardiography in pre-adolescents

This study examined factors contributing to the differences in left ventricular mass as measured by Doppler echocardiography in children. Fourteen boys (10.3 ± 0.3 years of age) and 1 1 girls (10.5 ± 0.4 years of age) participated in the study. Height and weight were measured, and relative body fat was determined from the measurement of skinfold thickness according to Slaughter et al. (1988). Lean Body Mass was then calculated by subtracting the fat mass from the total body mass. Sexual maturation was self-assessed using the stages of sexual maturation by Tanner (1962). Both pubic hair development and genital (penis or breast for boys and girls respectively) development were used to determine sexual maturation. Carotid Pulse pressure was assessed by applanation tomometry in the left carotid artery. Cardiac mass was measured by Doppler Echocardiography. Images of cardiac structures were taken using B-Mode and were then translated to M- Mode. The dimensions at the end diastole were obtained at the onset of the QRS complex of the electrocardiogram in a plane through a standard position. Measurements included: (a) the diameter of the left ventricle at the end diastole was measured from the septum edge to the endocardium mean border, (b) the posterior wall was measured as the distance from to anterior wall to the epicardium surface, and (c) the interventricular septum was quantified as the distance from the surface of the left ventricle border to the right ventricle septum surface. Systolic time measurements were taken at the peak of the T-wave of the electrocardiogram. Each measurement was taken three to five times before averaging. Average values were used to calculate cardiac mass using the following equation (Deveraux et al. 1986). Weekly physical activity metabolic equivalent was calculated using a standardize activity questionnaire (Godin and Shepard, 1985) and peakV02 was measured on a cycloergometer. There were no significant differences in cardiovascular mesurements between boys and girls. Left ventricular mass was correlated (p<0.05) with size, maturation, peakV02 and physical activity metabolic equivalent. In boys, lean body mass alone explained 36% of the variance in left ventricular mass while weight was the single strongest predictor of left ventricular mass (R =0.80) in girls. Lean body mass, genital developemnt and physical activity metabolic equivalent together explained 46% and 81% in boys and girls, respectively. However, the combination of lean body mass, genital development and peakV02 (ml kgLBM^ min"') explained up to 84% of the variance in left ventricular mass in girls, but added nothing in boys. It is concluded that left ventricular mass was not statistically different between pre-adolescent boys and girls suggesting that hormonal, and therefore, body size changes in adolescence have a main effect on cardiac development and its final outcome. Although body size parameters were the strongest correlates of left ventricular mass in this pre-adolescent group of children, to our knowledge, this is the first study to report that sexual maturation, as well as physical activity and fitness, are also strong associated with left ventricular mass in pre-adolescents, especially young females. Arterial variables, such as systolic blood pressure and carotid pulse pressure, are not strong determinants of left ventricular mass in this pre-adolescent group. In general, these data suggest that although there is no gender differences in the absolute values of left ventricular mass, as children grow, the factors that determine cardiac mass differ between the genders, even in the same pre-adolescent age.

Left ventricular structure in children with developmental coordination disorder

Developmental coordination disorder (p-DCD) is a neuro-developmental disorder featuring impairment in developing motor coordination. This study examined left ventricular mass (LVM) in children with p-DCD (n=63) and controls (n=63). LVM was measured using echocardiography. Body composition was determined using BOD POD and peak oxygen uptake (peak V02) was measured by a progressive exercise test. Height, weight and blood pressure were also measured. LVM was not significantly elevated in p-DCD compared to controls. Peak V02 was lower and SBP, BMI, HR, and BF(%) were significantly higher in p-DCD. They also demonstrated elevated stroke volume (SV), cardiac output (CO), end-diastolic volume, and ventricular diameter in diastole. In regression analyses, p-DCD was a significant predictor of SV and CO after accounting for height, FFM, V02FFM, and sex. These differences in children with p-DCD indicate obesity related changes in the left ventricle and may represent early stages of developing hypertrophy of the left ventricle.

Sélection de gènes de référence pour la normalisation des expériences de PCR quantitative dans un modèle de dysfonction diastolique de lapin

La dysfonction diastolique du ventricule gauche (DDVG) réfère à une rigidité ainsi qu’à des troubles de relaxation au niveau de ce ventricule pendant la phase de la diastole. Nos connaissances sur les mécanismes moléculaires sous-jacents de cette pathologie demeurent limités. Les analyses géniques sont indispensables afin de bien identifier les voies par lesquelles cette maladie progresse. Plusieurs techniques de quantification de l’expression génique sont disponibles, par contre la RT-qPCR demeure la méthode la plus populaire vu sa haute sensibilité et de ses coûts modérés. Puisque la normalisation occupe un aspect très important dans les expériences de RT-qPCR, nous avons décidé de sélectionner des gènes montrant une haute stabilité d’expression dans un modèle de DDVG de lapin. Nous avons alors exposé 18 lapins blancs soit à une diète normale (n=7) ou bien à une diète hypercholestérolémiante additionnée de vitamine D2 (n=11). La DDVG a été évaluée par des mesures échocardiographiques. L’expression de l’ARNm de dix gènes communément utilisés dans la littérature comme normalisateur (Gapdh, Hprt1, Ppia, Sdha, Rpl5, Actb, Eef1e1, Ywhaz, Pgk1, et G6pd) a été mesurée par RT-qPCR. L’évaluation de leur stabilité a été vérifiée par les algorithmes de geNorm et Normfinder. Sdha et Gapdh ont obtenu les meilleurs scores de stabilité (M<0.2) et ont été suggérés par le geNorm, comme meilleure combinaison. Par contre, l’utilisation de Normfinder mène à la sélection d’Hprt1 et Rpl5 comme meilleure combinaison de gènes de normalisation (0.042). En normalisant par ces deux combinaisons de gènes, l’expression de l’ARNm des peptides natriurétiques de type A et B (Anp et Bnp), de la protéine chimiotactique des monocytes-1 (Mcp-1) et de la sous unité Nox-2 de la NADPH oxydase ont montré des augmentations similaires chez le groupe hypercholestérolémique comparé au groupe contrôle (p<0.05). Cette augmentation d’expressions a été corrélée avec plusieurs paramètres échocardiographiques de DDVG. À notre connaissance, c’est la première étude par laquelle une sélection de gènes de référence a été réalisée dans un modèle de lapin développant une DDVG.

Dinámica del anillo mitral en pacientes con insuficiencia mitral isquemica

OBJETIVOS: Describir y comparar los cambios dinámicos de la geometría del anillo mitral durante todo el ciclo cardiaco en pacientes con insuficiencia mitral isquémica y pacientes con válvula mitral normal. MATERIALES Y MÉTODOS: Los estudios ecocardiográficos analizados fueron 37, 23 con insuficiencia mitral isquémica y 14 con válvula mitral normal. La reconstrucción del anillo se realizó en la estación de trabajo Xcelera (Philips Medial Systems) mediante la herramienta de análisis mitral (MVQ), en 5 momentos del ciclo cardiaco: Comienzo de Sístole, Mitad de Sístole, Final de Sístole, Mitad de Diástole y Final de Diástole. RESULTADOS: El anillo del grupo control, fue más dinámico, con sus menores dimensiones al final de la diástole, presentando incremento progresivo durante la sístole. Los cambios en el perímetro y el área, fueron significativos entre el comienzo y mitad de la sístole (p:0.087 y p: 0.055). En el grupo con insuficiencia mitral isquémica, el anillo fue más estático. Todas las dimensiones en este grupo, fueron mayores en los cinco momentos del ciclo cardiaco. (p < 0.1). El anillo también fue más plano, con un índice morfológico anular menor al del grupo control (p:0.087). DISCUSIÓN Y CONCLUSIONES: En pacientes sin insuficiencia mitral, el anillo es una estructura dinámica. Durante la sístole, las menores dimensiones se produjeron al comienzo de este periodo y la conformación en silla de montar se mantuvo, protegiendo contra la insuficiencia mitral. El anillo del grupo con insuficiencia mitral fue más estático y plano, perdiendo los mecanismos protectores.

Variación de volumen sistólico como predictor de hipovolemia en pacientes pediátricos con choque séptico

El compromiso del sistema cardiovascular es frecuente en los pacientes en estado crítico, por tanto la monitorización hemodinámica es esencial para un tratamiento apropiado dirigido a objetivos terapéuticos en este grupo de pacientes. La monitorización hemodinámica del gasto cardíaco y la estimación del volumen intravascular son fundamentales para el manejo de los pacientes pediátricos en estado crítico, la medición del gasto cardíaco es uno de los principales elementos para evaluar la situación hemodinámica y la perfusión tisular de un paciente ayudando a dirigir el tratamiento y a monitorizar la respuesta clínica en pacientes con choque séptico. La hipovolemia es una causa común para la falla circulatoria en pacientes en condición crítica, el encontrar un método confiable para medición de precarga es importante para guiar la administración de líquidos. Tradicionalmente se han utilizado medidas de la volemia asociadas como la presión venosa central (PVC), frecuencia cardiaca (FC), presión arterial (PA) y el gasto urinario. Estos indicadores tienen grandes factores de distracción que hacen que su valor sea limitado y por tanto se tengan que buscar alternativas más confiables. En años recientes se han postulado parámetros dinámicos para la evaluación de la precarga, entre ellos uno de los mas ampliamente estudiado es la medición de la variabilidad de Volumen sistólico (VVS); Este valor se basa en el concepto de que durante la inspiración, la disminución del retorno venoso produce una disminución del Volumen sistólico, lo cual se manifiesta como una disminución en la onda de pulso; Por tanto en una situación de hipovolemia esta diferencia será mayor, dado que será más evidente la disminución del volumen al final de la diástole. En adultos este parámetro se ha convertido en una herramienta útil para evaluar estado de volumen de los pacientes que se encuentran en estado crítico y ha demostrado su utilidad para predecir respuesta a administración de fluidos en diferentes poblaciones de pacientes. En la actualidad no hay estudios en niños que comparen la medición de VVS contra dichas medidas tradicionales de volemia.

Prevalencia de anormalidades estructurales cardiacas en pacientes con enfermedad isquémica. Bogotá 2007 – 2009

Introducción: Las enfermedades cardiovasculares son la causa de muerte más frecuente en el mundo desarrollado, la mayoría de éstas se relacionan con alteraciones de las arterias coronarias, sin embargo un subgrupo de pacientes presentan como causa de isquemia cardiaca alteraciones estructurales. Material y métodos: Estudio Descriptivo. Se utilizó la base de datos recolectada en un servicio de hemodinamia de Bogotá durante dos años. Se aplicaron criterios de inclusión y exclusión y se determinaron cuatro grupos etáreos, a todos los pacientes se les practicó cateterismo cardiaco diagnóstico. Las variables analizadas fueron: diagnóstico de referencia, antecedentes y resultados del cateterismo incluyendo presencia de anomalías estructurales como las valvulopatias, el origen anómalo de las coronarias y los puentes miocárdicos. Para el análisis descriptivo se utilizó reporte de prevalencias y para el análisis de asociaciones se utilizaron tablas de contingencia y el estadístico de prueba Chi cuadrado, no se realizó análisis multivariado debido a que no se encontraron asociaciones estadísticamente significativas. Resultados: La edad promedio de los pacientes fue de 62 años (DS= 10,5), la representación del género masculino fue del 61,7%, la prevalencia de angina estable fue del 61,6%, los 3 antecedentes más prevalentes fueron: hipertensión arterial (41,4%), la hiperlipidemia (19,1%) y la Diabetes Mellitus (17,7%). La prevalencia de las alteraciones estructurales en la población de estudio de manera general fue del 12,9%, y su distribución por tipo fue: 1,4% para puentes miocárdicos, 0,7% para origen anómalo de las arterias coronarias y 10,8% de enfermedad valvular. Conclusiones: Se encontró una asociación entre los antecedentes médicos y la presencia de valvulopatias cardiacas. Se evidenció que el género no tiene relación con la presencia de alteraciones cardíacas a pesar de la mayor participación de hombres en la población de estudio. Las limitantes de este estudio se relacionaron con el tamaño de muestra, debido a la baja prevalencia de las anomalías estructurales medidas.