End-organ Pathology in Childhood Essential Hypertension

BACKGROUND:

Elevated blood pressure has been established as an important risk factor for the development of cardiovascular disease morbidity and mortality. The major manifestations of end-organ pathology associated with hypertension include congestive heart failure, ischemic heart disease, stroke, and peripheral artery disease, including renal failure and retinopathy. As blood pressure has been studied in children, it has become evident that adult essential hypertension and its complications may have origins in adolescence and childhood. Clinical observations have shown that some individuals with elevated blood pressure will develop one form of morbidity, while others develop a different form, and still others do not develop any complications. The reasons for this are unknown. Few studies have been done which attempt to delineate risk factors for the development of the different end-organ pathologies in hypertensive individuals. Two end-organ problems are particularly amenable to study in children. Ultrasound examination of the heart allows the non-invasive study of left ventricular hypertrophy which is an important precursor to the development of congestive heart failure. Retinal examination by fundal photograph and fluorescein angiography allows the examination of the effects of elevated blood pressure on the vessels of the eye.

DESIGN NARRATIVE:

The first phase of the study had a cross-sectional design. In this phase, echocardiography was used to measure left ventricular dimensions, mass, volume and function and fundoscopic examination and fluorescein angiography were used to determine retinal vascular abnormalities. Data were collected on the independent variables of age, sex, race, obesity, level and duration of increased blood pressure, ambulatory variability of blood pressure, family history of hypertension, treatment with antihypertensive medication, sodium intake, smoking, alcohol use, fasting blood glucose, hemoglobin, basal plasma renin activity, plasma catecholamines, cardiovascular reactions to mental stress and to exercise. Multiple regression analysis was used to determine which of the independent variables were independently associated with left ventricular mass, creatinine clearance, and retinal vascular abnormality.

The second phase of the study was a longitudinal investigation of the development of left ventricular hypertrophy, changes in left ventricular function and retinal vascular disease, and the temporal relationship of these complications to the risk factors found in the first phase, using a cohort design.