Background: Coarctation (narrowing) of the aorta occurs in 1/2,500 newborns, and its delayed diagnosis may result in neurologic injury and death. The ductus arteriosus is an essential blood vessel in the fetus, connecting the pulmonary artery to the aorta, bypassing the fetal lungs. In 20-50% of preterm infants, the ductus arteriosus remains open after birth (PDA - patent ductus arteriosus). Left-to-right PDA shunting may increase the pulmonary blood flow and decrease the systemic perfusion, which may lead to severe morbidity.
Method: Photoplethysmography (PPG) is the measurement of changes in light transmission through an extremity due to cardiac-induced blood volume changes. Changes in two PPG pulse parameters in hand and foot, due to coarctation or PDA were examined: relative pulse amplitude (rAM) and foot-hand time-delay (f-hTD). Presence of coarctation and PDA was determined by echocardiography.
Results: In infants with coarctation, compared to healthy newborns, f-hTD was significantly prolonged (71.8±27.5 milliseconds (ms) vs 35.0±8.4ms, p=0.00003) and rAM value was significantly lower (0.57±0.25 vs 0.95±0.53, p=0.016). In newborns with PDA, foot rAM was significantly higher than in newborns without PDA (Median: 1.36 vs 1.14, 95%CI: 1.19 to 2.04 vs 0.95 to 1.53, P=0.028). Despite the lower systemic perfusion in PDA, rAM was higher, probably due to reverse blood flow during diastole.
Conclusion: Foot-hand time-delay is prolonged in coarctation and the relative foot PPG amplitude decreased in coarctation and increased in PDA newborns. PPG parameters of the extremities may be utilized as a simple and convenient screening modality for congenital heart diseases in newborns.