Maturational and adaptive modulation of left ventricular torsional biomechanics: Doppler tissue imaging observation from infancy to adulthood.

BACKGROUND: Left ventricular (LV) torsional deformation, based in part on the helical myocardial fiber architecture, is an important component of LV systolic and diastolic performance. However, there is no comprehensive study describing its normal development during childhood and adult life. METHODS AND RESULTS: Forty-five normal subjects (25 children and 20 adults; aged 9 days to 49 years; divided into 5 groups: infants, children, adolescents, and young and middle-age adults) underwent assessment of LV torsion and untwisting rate by Doppler tissue imaging. LV torsion increased with age, primarily owing to augmentation in basal clockwise rotation during childhood and apical counterclockwise rotation during adulthood. Although LV torsion and untwisting overall showed age-related increases, when normalized by LV length, they showed higher values in infancy and middle age. The proportion of untwisting during isovolumic relaxation was lowest in infancy, increased during childhood, and leveled off thereafter, whereas peak untwisting performance (peak untwisting velocity normalized by peak LV torsion) showed a decrease during adulthood. CONCLUSIONS: We have shown the maturational process of LV torsion in normal subjects. Net LV torsion increases gradually from infancy to adulthood, but the determinants of this were different in the 2 age groups. The smaller LV isovolumic untwisting recoil during infancy and its decline in adulthood may suggest mechanisms for alterations in diastolic function.

Use of a straight, side-hole delivery sheath for improved delivery of Amplatzer ASD occluder.

The Amplatzer ASD occluder may be difficult to position in some patients with a large atrial septal defect (ASD) or deficiency of one or more atrial septal rims. We developed a method to modify a Mullins transseptal sheath to enhance delivery. The resulting sheath is straight and has an exit orifice essential in the side of the distal portion of the sheath-a straight, side-hole (SSH) delivery sheath. We have used this modified delivery sheath in 140 successive patients with excellent results. The techniques of sheath modification and delivery of the device using the modified sheath are described.