CARDIOVASCULAR JOURNAL OF AFRICA • Vol 23, No 3, April 2012
AFRICA
179
The young hypertensive
Prof Brian Rayner
Hypertension is increasingly becoming a
health concern in the younger population.
Prof Rayner illustrated this point by
comparing current statistics with data
from the 1970s, when hypertension in
children was extremely rare and almost
always prompted investigation to search
for an underlying secondary cause.
Recent American studies have
shown that the prevalence of childhood
hypertension has risen as high as 4.5%.
The Harvard Alumni study assessing
coronary heart disease mortality in normal
subjects and those with pre-, primary and
secondary hypertension found that 5–15%
of adolescents displayed secondary
hypertension.
Factors contributing to childhood
hypertension
‘The current epidemic of obesity is the
key issue in childhood hypertension’,
said Prof Rayner. Obesity is defined
as a body mass index above the 85th
percentile, leading to a rise in leptin
levels and heart rate, and also linked to
insulin resistance. He noted that a definite
relationship between blood pressure and
fasting insulin has been observed.
A number of other factors are also
strongly linked to the rise in childhood
hypertension, including low birth weight
and predisposing genetic factors (family
history of risk factors or hypertensive
disease). Also contributing are reduced
nephron number (Barker-Brenner
hypothesis) and elevated uric acid.
There are multiple health concerns
around elevated blood pressure in
childhood. Childhood blood pressure
(especially systolic) tracks blood pressure
into adulthood. Elevated blood pressure is
associated with subclinical cardiovascular
disease and is a significant driver of
overall mortality, cardiovascular mortality
and coronary heart disease.
Assessing hypertension in the
child
Key pointers to primary hypertension in
the child include adolescence, obesity,
and a family history of hypertension,
cardiovascular disease and type 2 diabetes.
Pre-hypertension and hypertension were
defined as a blood pressure persistently
above the 90th and 95th percentiles,
respectively. Adult norms of blood
pressure should be used from 18 years
of age.
Prof Rayner advised that assessment
of blood pressure should be based
on frequent measures; full 24-hour
ambulatory monitoring is ideal to avoid
misdiagnosis. Clinical examination
should evaluate for potential secondary
causes of hypertension, particularly
use of illicit drugs (cocaine, tik) and
oral contraceptives, and chronic kidney
disease.
Other investigations advised included
a dipstick for urine, and creatinine
assessment, as well as kidney ultrasound.
Blood tests (electrolyte, uric acid and
fasting glucose levels, lipogram), an
electrocardiogram and an echocardiogram
were also considered important.
Treatment of childhood
hypertension
Lifestyle modification, Prof Rayner
emphasised, forms the basis of treatment
of the pre-hypertensive or hypertensive
child. Weight loss and increased exercise
are of particular importance.
The use of therapeutic agents should
be considered in those children with
symptomatic hypertension, secondary
hypertension, organ damage and type 1
and 2 diabetes. Also consider those with
persistent hypertension despite lifestyle
modification.
There are some concerns over the use
of diuretics in the young, but the use of
angiotensin converting enzyme (ACE)
inhibitors or angiotensin receptor blockers
(ARB), calcium channel blockers and
beta-blockers has been safely established.
Prof Rayner did comment that weight
gain and poor exercise tolerance arising
from beta-blocker use predisposes the
patient to type 2 diabetes.
G Hardy
HEALTHCARE
Prof Brian Rayner
Head of Division of Nephrology,
Groote SchuurHospital andUniversity
of Cape Town
Active research interests are therapy of
hypertension, mutations in the ENaC,
genetic determinants of salt sensitivity,
HIVAN, vascular calcification and
chronic kidney disease, primary
aldosteronism and the genetics of
severe hypertension in blacks.
continued from page 176
systolic blood pressure at six months.
Medically controlled patients were
eligible to crossover to RDN at six
months.
All patients were followed for one
year to assess long-term effectiveness
and safety of RDN. At least 12 months’
data for 47 RDN patients and 35
crossover patients were available with
regard to efficacy.
Both groups showed a similar
significant drop of 25–30 mmHg
systolic blood pressure and 10 mmHg
diastolic blood pressure, whether they
underwent the procedure at zero or six
months. The procedure was safe with no
adverse events, except for one patient
who had a right renal artery dissection.
1.
Krum R,
et al.
Long-term follow-up of
catheter-based renal sympathetic denerva-
tion for resistant hypertension confirms
durable blood pressure reduction. ACC
congress 2012, Abstract 926-3.
2.
Esler MD, Krum H, Schlaich M,
et al
.
Renal sympathetic denervation for treat-
ment of resistant hypertension: one
year results from the simplicity HTN-2
randomised controlled trial. ACC congress
2012, Abstract 926-4.
