Hypertension in children

Up until a few years ago, hypertension in children and adolescents was regarded as a clinical problem of lesser importance than the hypertensive state in adults, based on two major beliefs.

1. First, the thinking that the physiological age-related increase in blood pressure which characterises the growth process may interfere with (and often render questionable) the diagnosis of a high blood pressure state.
2. Second, the belief that blood pressure elevation in children is rare and less dangerous than in adults, due to the common opinion that childhood is a condition characterized by low cardiovascular risks.

Two sets of data have drastically modified these concepts. Epidemiological studies have shown that the prevalence of the hypertensive state in children is by no means irrelevant (2), particularly when :

1. An overweight or an obese state is concomitantly present and
2. Appropriate blood pressure measurements and proper interpretation of tables of blood pressure percentiles are performed.

In addition some sets of data provide evidence that high blood pressure may cause and/or be associated with an elevated cardiovascular risk in children as well (2).

The ESH Guidelines on the management of high blood pressure in children.

The ESH Guidelines document represent the fist attempt made by a European Society to comprehensively address the complex issue of diagnosis, evaluation and treatment of the hypertensive state in childhood. Previous antecedents to this editorial endeavour are represented by the documents issued by the National High Blood Pressure education program Working Group on High Blood Pressure in Children (3-4) which only in part provide practical recommendations capable of guiding current clinical practice. The main features of the Guidelines will be briefly discussed thereafter under separate headings.

I -  Definition

The ESH guidelines emphasise the importance of integrated blood pressure measurements into current pediatric clinical practice, providing a classification of hypertension that takes the physiological pattern of the blood pressure increase in the first 2 decades of life into account (Table 1).

A novel concept introduced by these Guidelines refers to the need to have blood pressure measurements other than clinic ones during the pediatric age as well, as we do in adults. Ambulatory blood pressure monitoring, in particular, is reported to be essential both for the diagnosis as well as for the management of pediatric hypertension (2). As it occurs in adults, ambulatory blood pressure monitoring in children has specific reference normality values, which are again expressed as percentile values for age, gender and height (5). As expected they are lower than the sphygmomanometric ones.

Important issues of future evaluation are in the definition of the 24 hour blood pressure profile pattern in hypertensive children, the presence or the absence in pediatric age of the non-dipping phenomenon as well as the existence at younger ages of the morning blood pressure surge.

2 - Diagnosis and evaluation

ESH Guidelines offer an algorithm for the hypertension diagnosis in childhood which is based on systolic and/or diastolic blood pressure values³ 95th percentile. Values between 90 th to 95th percentile require accurate follow-up based on repeated blood pressure measurements throughout months without immediate pharmacological interventions.

Once the hypertensive state is diagnosed, the assessment of the patient should be based on routine laboratory investigations and eventually more sophisticated (so called "second step") examinations in order to rule out the presence of secondary hypertension as well as target organ damage. This latter evaluation should also include echocardiography (again reference values are expressed in percentiles), carotid ultrasonography, search for microalbuminuria and, in specific cases, cranial computed tomography, magnetic resonance imaging technique and fundoscopy. Search for microalbuminuria is of particular relevance because it also holds in the first decades of life a relevant prognostic significance which is not affected (as it happens in adult hypertension) by the concomitant presence of comorbities.

Needless to say that in childhood special attention should be payed to excluding secondary hypertension, whose prevalence at the pediatric age appears to be greater than in adults (1). Screening for secondary hypertension is mandatory in children and teenagers, the most common secondary hypertensive form being represented by renal parenchimal alterations (glomerulonephritis, polycystic kidney, renal artery stenosis) and coartaction of the aorta (1). In the suspicion of a secondary hypertensive state specific biochemical and instrumental examinations are required, as it happens in adults.

3 - Therapeutic approach

Along with life-style interventions, which are of major importance particularly when hypertension is detected in overweight or in obese children, Guidelines extensively discuss pharmacological intervention, which has to be initiated in cases where hypertension is symptomatic, has a secondary nature, or when is complicated by target organ damage or diabetes mellitus type 1 or 2.

Blood pressure goals during treatment are set at values below the 95th age, gender and height percentiles, although 90th percentiles probably offer greater protection. To achieve such goals, the drug classes for adults can be used in pediatric hypertension, with the only exception being diuretics, which have no documented evidence of clinical use in children. The same apply for direct vasodilators, central agents and alpha-blockers.

The four drug classes which are to be used in paediatric hypertension are beta-blockers, calcium antagonists, ACE-inhibitors and angiotensin II receptor blockers, starting with low-dose monotherapy and, if necessary, implementing the dose or, preferentially, making use of low dose combination treatment in order to avoid the occurrence of side-effects. The follow-up of the treated young patient should be based on regularly scheduled visits, with the aim at obtaining full blood pressure control.

A key but still unanswered question is temporal duration of antipertensive drug treatment in children. The suggestion, also from the ESH Guidelines, is not to stop treatment in childhood, even when blood pressure displays a good control and no target organ damage is present (low risk category). A more conservative behaviour in this case is to take advantage of the low dose single drug treatment approach.

4 - Current position and perspectives

The ESH Guidelines on hypertension in children have several merits, the most important being the attempt to provide a detailed guide on what to do in presence of a high blood pressure state in children. They also have limitations, as properly emphasised by the authors. These limitations, however, are mainly due to the partial or total lack of information we still have on some specific issues discussed in the document, such as the lack of evidence on the long-term effects of treatment on prognosis and regression of organ damage in children. These issues will thus become priorities for future investigations.

SBP : systolic blood pressure; DBP : diastolic blood pressure. Modified from Ref 1.