Several indexes of myocardial contractility have been proposed to assess ventricular function in the isovolumetrically beating isolated heart. However, the conclusions reached on the basis of these indexes may be influenced by ventricular geometry rather than contractility itself. The objective of the present study was to assess the performance of widely used contractility indexes in the isovolumetrically beating isolated heart in two experimental models of hypertrophy, the spontaneously hypertensive rat (SHR) and infrarenal aortocava fistula. Compared to normotensive controls (N = 8), SHRs with concentric hypertrophy (N = 10) presented increased maximum rate of ventricular pressure rise (3875 ± 526 vs 2555 ± 359 mmHg/s, P < 0.05) and peak of isovolumetric pressure (187 ± 11 vs 152 ± 11 mmHg, P < 0.05), and decreased developed stress (123 ± 20 vs 152 ± 26 g/cm 2 , P < 0.05) and slope of stress-strain relationship (4.9 ± 0.42 vs 6.6 ± 0.77 g/cm 2 /%). Compared with controls (N = 11), rats with volume overload-induced eccentric hypertrophy (N = 16) presented increased developed stress (157 ± 38 vs 124 ± 22 g/cm 2 , P < 0.05) and slope of stress-strain relationship (9 ± 2 vs 7 ± 1 g/cm 2 /%, P < 0.05), and decreased maximum rate of ventricular pressure rise (2746 ± 382 vs 3319 ± 352 mmHg, P < 0.05) and peak of isovolumetric pressure (115 ± 14 vs 165 ± 13 mmHg/s, P < 0.05). The results suggested that indexes of myocardial contractility used in experimental studies may present opposite results in the same heart and may be influenced by ventricular geometry. We concluded that several indexes should be taken into account for proper evaluation of contractile state, in the isovolumetrically beating isolated heart.

ResumoObjetivos: Avaliar a morfologia e função cardíaca através do ecocardiograma em crianças com obstrução respiratória no sono. Métodos:Foram estudadas 40 crianças de ambos os sexos, com idade entre 3 e 11 anos, sendo que 30 apresentavam obstrução respiratória no sono (grupo I) e 10 crianças eram controles saudáveis (grupo II). Os dois grupos eram semelhantes quanto a gênero, idade, peso e altura. As 40 crianças realizaram ecocardiograma, visando às quatro câmaras em sístole e diástole, com atenção especial ao ventrículo direito. Os dados obtidos foram comparados através do teste t de Student (p < 0,05).Resultados: Observou-se, no grupo I, aumento do diâmetro e da área do ventrículo direito em sístole e diástole. A variação entre sístole e diástole da área do ventrículo direito era menor. Em ventrículo esquerdo, foi observada diminuição do diâmetro diastólico, uma menor fração de ejeção e um encurtamento menor. Conclusões:As alterações morfológicas e funcionais cardíacas encontradas em ventrículo direito e ventrículo esquerdo sugerem que obstrução respiratória no sono em crianças pode levar a repercussões cardiovasculares. Estas alterações podem expor as crianças a um maior risco anestésico e cirúrgico.J Pediatr (Rio J). 2007;83(6):518-522: Apnéia do sono obstrutiva, criança, ecocardiografia. AbstractObjectives: To assess cardiac morphology and function by means of echocardiograms of children with obstructed 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.J Pediatr (Rio J). 2007;83(6):518-522: Obstructive sleep apnea, child, echocardiography. IntroduçãoO quadro clínico de obstrução das vias aéreas superiores (VAS) no sono varia de intensidade, desde roncos noturnos à síndrome da apnéia hipopnéia obstrutiva do sono (SAHOS) 1 .A SAHOS é caracterizada por episódios repetidos de obstrução das VAS, associados à hipóxia e hipercapnia intermitente 1,2 . Sua prevalência nas crianças varia de 0,7 a 3% nos diferentes estudos epidemiológicos [3][4][5] . O seu pico de incidên-cia é observado...

Purpose:To study the effectiveness of the continuous, blood, antegrade-retrograde cardioplegia in an experimental model of isolated heart, evaluating ventricular function. Methods: Rabbits were divided into four groups: Control-C(n=10); ischemic crystalloid cardioplegia-IC(n=10); ischemic blood cardioplegia-IB(n=10); ischemic non cardioplegia-INC(n=10). After the ischemic protocol period the ventricular function was analyzed by the intra-ventricular balloon technique.

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