Estradiol promotes sudden cardiac death in transgenic long QT type 2 rabbits while progesterone is protective.

Background: Postpubertal women with inherited long QT syndrome type 2 (LQT2) are at increased risk for polymorphic ventricular tachycardia (pVT) and sudden cardiac death (SCD), particularly during the postpartum period.

Objective: To investigate whether sex hormones directly modulate the arrhythmogenic risk in LQTS.

Methods: Prepubertal ovariectomized transgenic LQT2 rabbits were treated with estradiol (EST), progesterone (PROG), dihydrotestosterone (DHT), or placebo (OVX).

Evaluation of Cooper 12-minute walk/run test as a marker of cardiorespiratory fitness in young urban children with persistent asthma.

Objective: To evaluate Cooper 12-minute run/walk test (CT12) as a one-time estimate of cardiorespiratory fitness and marker of fitness change compared with treadmill fitness testing in young children with persistent asthma.

Design: A cohort of urban children with asthma participated in the asthma and exercise program and a subset completed pre- and postintervention fitness testing.

Setting: Treadmill fitness testing was conducted by an exercise physiologist in the fitness laboratory at an academic children's hospital.