The Mystery of Hypertension

1. Blood pressure maintenance is a highly dynamic process with diurnal variations and significant fluctuations in response to neurocardiac reflexes such as anxiety, fear, a strange environment, etc. Therefore, blood pressure can vary as much as 60-80 mmHg or more at very short intervals.

2. Most hypertensive patients are on some kind of diuretics or vasodilators. Marked fluctuations in blood pressure are observed based on pharmacokinetics of the drug. For example, a hypertensive patient had a blood pressure of 190/110 at 7:00 a.m. recorded by an electronic device. Following 40 mg of p.o. Lasix and 10 mg of Vasotec, at about 10 a.m. the blood pressure recorded was 130/100 in the primary care physician’s office. I saw the same patient at about 2:00 p.m. for a pacer check and cardiac follow-up visit. Her blood pressure was 230/140, 220/135, and 214/135 on three measurements. The quick natriuresis and volume depletion from Lasix, the effect of Vasotec, and the blood pressure measuring techniques are responsible for these wide blood pressure variations. Very potent short-acting loop diuretics are not ideal for long-term treatment of hypertension. One must use a low dose, long-acting diuretic for slow sustained natriuresis, and prolonged blood pressure control.

3. Elderly hypertensive patients exhibit remarkable blood pressure variations after meals particularly breakfast. A significant drop in systolic blood pressure, as much as 50-60 mmHg, can be seen following a heavy breakfast secondary to splanchnic blood pooling and the relatively poor sympathetic tone early in the morning.

4. Arteriosclerosis seen in the elderly and the resultant stiffness of the vessel makes cuff blood pressure measurement inaccurate.

5. One must use a high quality, well-calibrated blood pressure cuff suited to the arm size and high fidelity stethoscope to measure blood pressure. In an elderly person with arteriosclerosis, it is difficult to occlude the brachial artery circulation by applying cuff pressure. Once it is finally occluded, and then gradually released for measuring blood pressure, the initial 30-40 mm of systolic blood pressures are often missed, as they are very faint and inaudible for an inexperienced caregiver.

6. Postural hypotension is not at all uncommon in elderly people. A blood pressure recorded in recumbent position, and that measured while sitting or standing, can have significant differences. This difference is often not identified or recorded, resulting in disparity of blood pressure measurement from one office to the other.

7. Subclavian and innominate artery stenosis is also not uncommon in the elderly population. There is a common tradition of measuring blood pressure only on the right arm. This tradition makes the blood pressure measurements susceptible to inaccuracies created by brachial artery stenosis. Therefore, I recommend blood pressure measurements on both arms.

Case Study

(Fig 7) The EKG and pressure tracings in the picture are obtained from an 85 year-old patient with unstable angina who underwent a cath-plasty procedure. The blood pressure during the pre-cath evaluation was 155/60, 165/60, etc., suggesting mild isolated systolic hypertension.

The picture shows three sets of blood pressures measured simultaneously. The solid arrow shows blood pressure of 183/57 is a direct measurement from the central aorta. The flagged arrow of blood pressure 193/56 is a direct measurement from the femoral artery. The open arrow with blood pressure of 160/67 is a simultaneous digital blood pressure reading from the left arm by a blood pressure cuff.

The disparities in the blood pressure readings are quite obvious. This patient certainly did not have subclavian artery stenosis (blood vessel to the upper limb), and the blood pressure on the right arm was identical to the one on the left arm. Obviously, the blood pressure measured by the cuff is very, very low and wrong. Ironically, cuff blood pressure is the one we always use for clinical assessments and pharmacological interventions.

In my overall clinical assessment, high blood pressure is more often underestimated than not. Measuring blood pressure in a patient with arteriosclerosis is a difficult task loaded with possibilities of errors. Our health care providers must be aware of the several variables that I have mentioned above.

Moreover, high blood pressure is mostly an asymptomatic disease. The side effects from medications are often unpleasant and inconvenient. The patient themselves love to hear that their blood pressure is normal. Some patients even have become very upset having noted this “grossly abnormal blood pressure” in my office, and will keep on justifying the blood pressure they saw at the nearby supermarket a few weeks back. The mystery of hypertension!

White Coat Hypertension The delineation and implication of white coat hypertension and sustained hypertension is not just clear as black and white. In fact, there is a subset of patients who have a very high blood pressure reading in a physician’s office, and may have a perfectly normal blood pressure reading on ambulatory blood pressure monitoring, who can be genuinely identified as white coat hypertensive patients. Hypertension is not an elevated blood pressure reading alone. It is a syndrome that encompasses anatomical changes in the cardiovascular system, end organ dysfunction, and allied biochemical aberrations. In these patients, the left ventricle is thicker and less compliant (LV mass index 10% above normal). They have more insulin resistance, hypertriglyceridemia, higher levels of plasma aldosterone and norepinephrine, just as in sustained hypertension. Therefore, this situation is not entirely normal. It is my belief that white coat hypertension is an overused and oversimplified version of labile hypertension, thereby escaping the proper diagnosis and treatment of hypertension. If a person is noted to have a blood pressure of 180 or 200 in the doctor’s office, and subsequently noted to have only 130 or 140 in the ambulatory setting, then that person must be identified as a hypertensive patient. Most of these patients have arteriosclerosis and are candidates to develop atherosclerosis.