Perioperative and Anesthetic Considerations in Truncus Arteriosus.

Truncus arteriosus is a congenital cardiac lesion in which failure of embryonic truncal septation results in a single semilunar valve and single arterial trunk providing both pulmonary and systemic circulations. Most patients with this lesion are symptomatic in the neonatal period with cyanosis and/or congestive heart failure and undergo complete repair in the first weeks of life. This review will focus on the anatomy, physiology, and perioperative anesthetic management of patients with truncus arteriosus.

Could submicroscopical chromosomal imbalances cause cono-truncal malformations in twins?

The course of normal heart formation in the embryo has been known for decades, but little is known about the genes that control its development. To further improve our understanding of the molecular and genetic mechanisms involved in congenital heart disease, we screened for submicroscopic chromosomal aberrations using bacterial artificial chromosome-based array comparative genomic hybridization analysis in two Danish twin pairs, one pair of monozygotic twins with tetralogy of Fallot, and one twin pair of unknown zygosity with pulmonary valve stenosis. We did not find any major chromosome defects, although a number of submicroscopic copy number variations were present. The question of whether these submicroscopic chromosomal imbalances alone or in conjunction with unknown intrauterine factors causes the observed cono-truncal malformations remains unanswered.

Cardiac outflow tract: a review of some embryogenetic aspects of the conotruncal region of the heart.

A review concerning some embryogenetic aspects of the cardiac outflow tract is presented. Two main topics are discussed: the truncal septation and the secondary heart field. In the context of the septation of the truncus arteriosus, the development of the arterial valves is largely discussed, particularly in reference to the sinuses of Valsalva. Emphasis is also given to the fate of the external myocardial wall of the truncus arteriosus, as this primordial myocardial surface disappears later in the development. Molecular genetics data concerning Sox4 and NF-Atc transcription factors are correlated in the present review with rare forms of truncus malformations encountered in human pathology. The roles exerted by the secondary heart field and the neural crest on the development and growth of the conotruncal musculature are largely discussed. Reported experimental ablations of both secondary heart field and neural crest, showed conotruncal defects such as persistent truncus arteriosus, tetralogy of Fallot, and double-outlet right ventricle, which were considered as the result of a short outflow tract causing, ultimately, a lack of conotruncal rotation. In this regard, some morphologic correlations are carried out, in the present review, between these experimental animal models and human malformations, and it is thought that this sort of conotruncal defects cannot be explained always in terms of conotruncal hypoplasia. Finally, influence of Pitx2c, a left-right laterality signaling gene, on the modulation of the conotruncal rotation, as most recently reported, is emphasized in terms of very likely multifactorial contributions in the embryogenesis of the conotruncal region of the heart.

Blood pressures and heart rate during larval development in the anuran amphibian Xenopus laevis.

Heart rate and blood pressure were measured in lightly anesthetized developing Xenopus laevis from hatching (body mass approximately 3 mg) to the end of metamorphosis (< or = 1 g). Blood pressures in the conus arteriosus, truncus arteriosus, and ventricle were measured by a servo-null micropressure system. Heart rate was determined from blood pressure recordings, and cardiac cycles were videotaped through a dissecting microscope. Heart rate varied from 50 to 150 beats/min and showed a negative correlation with body mass, with a slope less than predicted from allometric equations based on adult vertebrates. Mean truncus pressures showed a positive correlation with body mass, increasing from 4 mmHg in a 25-mg larva to 9 mmHg in a 1-g larva. The pressure waveform during ventricular systole was similar in all developmental stages examined, whereas those in conus and truncus varied with development. Conus pressures differed distinctly from truncus pressure during diastole in all larvae examined, suggesting the existence of functional valves between conus and truncus as early as stage 46 of the Nieuwkoop-Faber larval staging system. Although the developmental patterns of heart rate and blood pressure in X. laevis showed significant correlation with body mass, body mass explained less than one-half of the variation in these variables. Therefore developmental factors other than body mass, such as changes in heart mass and the addition of new resistance vessels, may influence heart rate and blood pressure during development in X. laevis.