Cardiac Function After the Immediate Transitional Period in Very Preterm Infants Using Speckle Tracking Analysis

The postnatal period in preterm infants involves multiple physiologic changes starting directly after birth and continuing for days or weeks. To recognize and treat compromise, it is important to measure cardiovascular function. We used a novel technique (speckle tracking echocardiography, STE) to measure cardiac function in this period. We obtained cardiac ultrasound images at day 3, 7, 14, 21 and 28 in preterm infants < 30-week gestation. Conventional measures included cardiac size, left ventricular stroke volume, atrial volume and the patent ductus arteriosus (PDA). Four chamber images were analyzed with STE, which provided parameters of left ventricular volume, longitudinal deformation and myocardial velocities. Images of 54 infants (gestational age 23-29 weeks) were analyzed. STE-derived stroke volume correlated well with conventional echocardiography-derived stroke volume, but agreement was suboptimal. Most STE parameters showed good reliability. All volume parameters and systolic and atrial velocities increased over time. Cardiac deformation and early diastolic velocity did not change. A PDA was associated with 33 % increased stroke volume at day 3 up to 98 % at day 28 with a spherically enlarged heart and increased filling pressure. Speckle tracking echocardiography analysis is a feasible and reliable technique that can simultaneously obtain systolic and diastolic volumes, longitudinal deformation and myocardial velocities from one ultrasound window. Preterm hearts maintain cardiac function well during the first weeks of life, even with increased preload as a consequence of a PDA.