１．高血圧 | 医療法人社団CVIC 仙川心臓クリニック

"You may have high blood pressure that needs treatment!"

What kind of illness is high blood pressure?

Blood pressure literally means "pressure in blood vessels", and hypertension means that systolic blood pressure is 140 mmHg or higher, diastolic blood pressure is 90 mmHg or higher, or both. It is estimated that there are about 43 million patients in Japan.

High blood pressure is a silent killer.

Hypertension (140/90 mmHg or higher) is the leading cause of life-threatening illnesses such as stroke and heart disease, two of the three leading causes of death in the Japanese. However, as hypertension is called a silent killer, only about 20% of the estimated 43 million hypertension patients in Japan are actually being treated because they have no subjective symptoms. It is said to be 8.6 million people. For high blood pressure, "it's okay if you don't have any subjective symptoms" doesn't work.

The World Health Organization (WHO) also recognizes hypertension as a major problem worldwide. In 2016, the World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC) jointly created cardiovascular disease prevention measures, of which hypertension is defined as a very important target.

Blood pressure

In April 2019, the Japanese Society of Hypertension announced the revised guidelines for hypertension treatment. As a result, the buck target value has been changed to less than 130/80 mmHg. If the above blood pressure is 130 to 140, it is not normal and is defined as "high blood pressure", and it is desirable to correct lifestyle habits and manage by exercise therapy (Table 1).

Table 1 Classification of blood pressure values in adults

(Modified from the Japanese Society of Hypertension Guidelines Hypertension Treatment Guidelines 2019)

The reason is that studies in Europe and the United States have reported that when blood pressure is 130/80 mmHg or higher, the incidence of cerebrovascular disease is higher than that of normal blood pressure. In the United States, the standard for hypertension has been changed to 130/80 mmHg or higher. In Japan, it is said that patients with hypertension often do not reach the optimum blood pressure. In recent years, there has been a trend to intervene earlier than before to prevent future cerebral infarction and myocardial infarction before arteriosclerosis due to hypertension progresses (Fig. 1).

Figure 1 SPRINT research results

(Modified from SPRINT Reseach Group et al. N Engl J Med 2015; 373: 2103-2116)

SPRINT study found that the severely hypotensive group had significantly fewer cardiovascular events (myocardial infarction, acute coronary syndrome, stroke, heart failure, cardiovascular death) during a median observation period of 3.26 years.

Complications of hypertension

It is well known that high blood pressure causes arteriosclerosis, but for the heart, persistent high blood pressure increases the burden on the heart, resulting in left ventricular hypertrophy. Left ventricular hypertrophy is a condition in which the thickness of the wall of the left ventricle increases due to the hypertrophy of cardiomyocytes in the left ventricular myocardium. As hypertension persists, hypertrophy progresses gradually.

Major cardiovascular events according to the MAVI study (2001), which prospectively followed 1,033 hypertensive patients aged 50 years and older without cardiovascular disease for an average of 3 years. The incidence of all deaths, including severe heart failure, renal failure requiring dialysis) was significantly higher in the group with left ventricular hypertrophy. It has been reported (Fig. 2). In addition, there are some patients who have an abnormality in cardiomyocytes and have an enlarged left ventricular myocardium. In that case, it is classified as cardiomyopathy called hypertrophic cardiomyopathy.

Fig. 2 Comparison of prognosis by weight of left ventricular myocardium in hypertensive patients

(Modified from Verdecchia et al. J Am Coll Cardiol 2001; 38: 1929-35)

Thus, left ventricular hypertrophy is one of the phenotypes of cardiac load, including hypertension. CVIC can detect wall thickness of the left ventricular myocardium and myocardial damage using cardiac MRI and echocardiography (echocardiography). As a result, even with the same high blood pressure, the degree of stress on the heart can be confirmed on the image.

Fig. 3 Cardiac MRI images at our hospital, comparison of normal and left ventricular hypertrophy

<Normal example>

<Example of left ventricular hypertrophy>

In normal cases, the left ventricular wall thickness is 6 mm, which is within the normal range, but in the right left ventricular hypertrophy case, the left ventricular wall thickness is 14.7 mm, which is a marked hypertrophy.

About treatment of high blood pressure

The first step in treating high blood pressure is to improve your lifestyle. In particular, the importance of salt reduction and regular aerobic exercise (walking for about 30 minutes a day, aqua size, cycling, slow jogging, etc.) is emphasized. It is important to start with what you can and determine the effect by regular home blood pressure measurements (ideally twice a day, morning and night). It has also been reported to have a blood pressure lowering effect in improving obesity. Daily weight measurement is also important. Even with these lifestyle-related improvements, if the blood pressure is high (140/90 or higher), drug treatment is indicated.

Drugs for treating high blood pressure are commonly called antihypertensive drugs because they lower blood pressure. There are various types of drugs (mechanism of action: efficacy), and the drug is selected according to the hypertension status and age of each patient. Recently, multiple drugs are often used in combination in small amounts, and a combination drug that combines them is often used.

In addition, most hypertension (about 90%) is essential hypertension of unknown cause. However, some (about 10%) hypertension is said to be secondary hypertension caused by overproduction of hormones from the adrenal glands. Most secondary hypertension can be screened with regular blood draws.

In most cases, it can be controlled with one or more antihypertensive agents. However, some uncontrolled patients are called refractory hypertension, and catheter-based renal denervation treatment has recently been clinically tested. Renal denervation treatment is a treatment method that suppresses sympathetic nerve activity by cauterizing the sympathetic nerves existing in the adventitia of the renal arteries using a catheter, and is expected to reduce blood pressure. In this way, hypertension is treated with various treatment methods, and I think that hypertension is an important issue.