Blood pressure and cardiac output during exercise: a longitudinal study of children undergoing repair of coarctation.

Data were examined from 21 children who underwent graded exercise studies prior to and within 5 years after repair of coarctation. A control group of 10 normal children was also studied longitudinally on two occasions. The exercise was performed on an upright bicycle ergometer using a continuous graded exercise protocol. Parameters measured were heart rate, systolic and diastolic blood pressure at rest, and these pressures at the maximal voluntary exercise level. In addition, a subset of patients and controls had measurement of cardiac output by a modified acetylene rebreathing technique. Results indicate that coarctation patients had significant elevation of systolic and diastolic blood pressures at rest (p less than 0.001 for both) and with exercise (p less than 0.02 for both) prior to surgery. The group mean values for systolic and diastolic blood pressure did not differ from control values after surgery; however, some individuals continued to have hypertension at rest when compared to population-based norms. Heart rate, cardiac index, and stroke volume index did not differ from those of control subjects either at rest or during exercise before or after surgery. In conclusion, a group of coarctation patients studied longitudinally demonstrated marked improvement in both systolic and diastolic hypertension after surgery. The findings of normal cardiac output and stroke volume indices may have implications for the etiology of postoperative hypertension.