Clinical update: Hypertension – In many cases, hypertension is only recognised when a cardiovascular event has occurred. While there are early vascular changes long before blood pressure rises, by the time the condition is recognised in many people they have already had a heart attack, stroke or suffered significant kidney damage.
However, this pattern of advanced high blood pressure combined with organ damage is becoming less common these days. “Clearly, visual loss, heart failure, stroke and kidney failure arise too late in the disease continuum for optimal intervention,” explained Dr Vincent Maher, Consultant Cardiologist at the AMNCH, Tallaght Hospital. He said there was a milder form of the condition, where other features were seen.
These included signs of organ damage, which preceded the stage at which people were most commonly detected. Left ventricular hypertrophy (LVH) preceded damage to the heart and heart failure, while retinal vascular changes that occur in the eye preceded visual loss. Proteinuria also preceded kidney damage.
Many consultants will opt to use an angiotensin-converting enzyme (ACE) inhibitor or an angiotensin receptor blocker (ARB) as first-line treatment. The evidence would not support beta blockers as first-line treatment, although a beta blocker might be considered where there is a patient with definite heart disease, angina or a fast heart-rate.
Calcium channel blockers are also used to treat high blood pressure. Fixed-dose combinations of ARBs plus calcium channel blockers are available, as are combined ACE inhibitors plus calcium channel blockers. Regimens combining olmesartan with amlodipine therapy are available. Therapy combining amlodipine plus perindopril is also available.
Another trend has seen a shift towards combinations of ACE inhibitors with an antihypertensive diuretic, such as Coversyl Arginine Plus. Micardisplus and Omesar Plus, meanwhile, combine ARBs with thiazide diuretics. Diuretics are useful in patients who are carrying more weight, as patients with high blood pressure tend to do. These patients improve with a fluid off-load.
There is a vogue in some quarters for triple therapy, involving an ACE or ARB plus calcium channel blocker, plus diuretic. One of the main side effects of calcium channel blockers is leg oedema. However, this is less marked when these agents are combined with an ACE or an ARB, and is even less prevalent when a diuretic is also used.
Higher levels of the hormone aldosterone are associated with ‘maladaptive processes’, including insulin resistance, inflammation, endothelial dysfunction and sodium retention.
These, in turn, contribute to resistant hypertension. Aliskiren (Rasilez), a direct renin inhibitor (DRI), works at the point of activation of the renin-angiotensin-aldosterone system (RAAS).
There is a obviously potential for long-term blood vessel damage, so clearly this is an area where early lifestyle intervention is useful. At his clinic in Tallaght Hospital, Dr Maher and his team have taken a particular interest in the insulin resistance syndrome. Two thirds of patients with high blood pressure have insulin resistance – a component in the metabolic syndrome.Central weight gain, diabetes and high blood pressure are all linked with each other. When central weight is gained, this aggravates blood pressure, diabetes and high cholesterol levels.
To optimise treatment, it is important to identify hypertensive patients early. Such a requirement for screening prompted the successful Heartwatch programme. GPs are increasingly aware that when a patient presents with high blood pressure during the consultation, waist circumference, cholesterol abnormalities, and the risk of diabetes should all be checked.
The presence of practice nurses means proper screening is being done, more time is devoted to checks and many more people with insulin resistance are being recognised.
The incidence of heart attacks has dropped considerably, but there is still a long way to go.
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