Cases analysis of rational use of medicine (49)White coat Hypertension (WCH)

1.Patient'sconditions

A Patient, 60-year-old female, had hypertension for half year, but her blood pressure was always normal at home or outside hospital.

Average 24-hour ambulatory pressure was 120～125/75～80 mmHg. She was suspected to have white coat hypertension(WCH).

Doctor's advice: nonpharmacological interventions, such as relaxing mental stress, keeping moderate physical activity, having sufficient sleep, modifying unhealthy dietary behavior and so on.

2.Analysis

(1)White coat hypertension

In hypertensive patients, readings recorded by physicians in the office or clinic tend to be higher than ones taken by patients at home. In normotensive subjects there is no marked difference. Twenty-four-hour ambulatory monitoring shows that in most hypertensive subjects, office pressures are also higher than the average 24-hour pressure, whereas in normotensive subjects, there is little difference. Thus, a clinic visit may provoke a rise of blood pressure to levels not commonly seen during daily life. The pressures recorded by a nurse in the clinic are typically lower than pressure by a physician and also closer to the levels seen outside the clinic.

The "alerting response to doctors" may explain why the clinic blood pressure tends to be higher. In patients with WCH, this response may be more stressing. The increase of blood pressure in response to acute stressors tends to be greater in patients with WCH than in normotensive subjects. It has been hypothesized that such increased reactivity may be a precursor or an etiological factor in the development of hypertension and that repeated exposure to stressors eventually leads to a sustained elevation of blood pressure in hyperreactive subjects.

The condition is seen in both men and women and may be more common in older than in younger subjects. Its etiology is unknown, recent studies suggest that the development of WCH may be associated with stress reaction, neuroregulation disturbance, mental (psychological) factors, metabolic disorder, endothelial dysfunction.

(2)Diagnosis

The condition may be suspected in patients in whom the clinic pressure remains elevated on successive visits but pressures measured outside the clinic or by a nonphysician are much lower. Its accurate diagnosis requires ambulatory monitoring, one commonly used criterion is a clinic pressure of 140/90 mmHg or higher and an average daytime ambulatory pressure of less than 135/85 mmHg or average 24-hour ambulatory pressure of below 130/80 mmHg. But up to now, the most scientific definition of diagnosis of WCH remains controversy.

(3)Target organ damage of WCH

The most important question clinically is whether such patients have any risk of cardiovascular morbidity. The studies used to show no signs of target organ damage and no development of cardiovascular events, so the treatment was not necessary. But, it now proves to be an intermediate stage between normotensive and sustained hypertension, and target organ damage has already occurred in patients, such as higher left ventricular mass index (LVMI),higher carotidendarterial thickening and atherosclerosis index, higher microalbuminuria (than normotension).The white coat hypertension is often together with other risk factors of cardiovascular diseases, such as hyperglycemia, dyslipoproteinemia, smoking etc, severity of which can dominate cardiovascular risks caused by WCH itself.

(4)Treatment of WCH

No clear treatment guidelines can be given at present, some studies showed pharmacological treatment had no good effects on the patients with WCH, some medical specialists in China, however, assert that positive antihypertensive treatments are absolutely necessary, because ①marked symptom manifests itself in many patients with WCH;②WCH tends to develop into sustained hypertension;③Target organ damages in the patients are often detected;④Other risk factors of cardiovascular disease are often found on the patients. On specialist's suggestion:①Pay close attention to the patient's heart, brain and kidney;②regularly measure ambulatory pressure of the patients;③modify patient's lifestyle, for instance, weight control and participation of manual labour, moderation of salt and alcohol intake, cessation of smoking, stress reduction ,and other bad behavioral changes.④Beta-Adrenergic blockers, Angiotensin-converting Enzyme Inhibitors (ACEIs),or calcium channel blockers (CCB) can be used, but they should be proved helpful in regular observation.