AORTIC PRESSURE WAVE REFLECTION AND CARDIAC BLOOD SUPPLY-WORKLOAD BALANCE FROM INFANTS TO YOUNG ADULTS

Objective: It is well-known that arterial stiffness increases with age from youth. Aortic pressure wave reflection is one of the indices of the arterial stiffness and elevates with aging. However, the augmentation index, which is one of the indices of aortic pressure wave reflection, is high during childhood. Slow return of aortic pressure reflection wave enhances cardiac blood supply-workload balance. Therefore, we examined the augmentation index and subendocardial viability ratio, which is one of the indices of cardiac blood supply-workload balance, from infancy to early adulthood. Design and method: We enrolled 100 subjects under 30 years of age, who underwent cardiac catheterization in Department of Pediatrics, Hokkaido University Hospital. The inclusion criteria were diagnosed as ventricular septal defect and atrial septal defect. The exclusion criteria were heart failure patients and patients with significant aortic level shunt. Ascending aortic pressure waveforms were recorded using a catheter-mounted pressure sensor (Millar, SPC-454D; Millar Instruments, Inc. Houston, TX) during cardiac catheterization. From the recorded pressure waveforms, we measured the systolic blood pressure, diastolic blood pressure, mean blood pressure, and pulse pressure in each patient. Moreover, we calculated an augmentation index and subendocardial viability ratio. Results: Patients’ age was 8.4 ± 6.4 years. The pulmonary-systemic flow ratio was 1.7 ± 0.8 and right ventricular systolic pressure was 31 ± 12 mmHg. The augmentation index was 4.1 ± 20.5% and subendocardial viability ratio was 1.01 ± 0.24. The augmentation index tended to decrease with increasing age until around mid-teen and then increase thereafter. The subendocardial viability ratio tended to increase with age until mi-teen and then decrease thereafter. There was a significant relationship between the augmentation index and subendocardial viability ratio (r = -0.45, p <0.0001) Conclusions: From infancy to early adulthood, the augmentation index decreases with age and becomes minimum when the patient’s height reaches its peak. It increases with age after that. The subendocardial viability ratio shows a reverse trend. There is a significant relationship between the aortic pressure wave reflection and cardiac blood supply-workload balance.