Generally speaking, human blood pressure fluctuates normally throughout the day. After waking up in the morning, blood pressure starts to rise gradually and reaches its highest value at noon; after lunch, it gradually drops to a lower level and rises again in the evening, reaching another peak in the day; until after going to sleep at night, it drops again, reaching its lowest value at about 2:00am~3:00am. A pattern of “two peaks and a valley” constitutes the normal fluctuation of human blood pressure.
However, for some special hypertensive patients, their blood pressure rises rapidly and dramatically after waking up in the morning and can last for 4~6h, a condition we call early morning hypertension, also known as morning peak blood pressure. Early morning hypertension is particularly damaging to the target organs of the human body, such as the heart and brain vessels, and also has unique features in treatment that deserve attention.
I. Determination of early morning hypertension
There is no international consensus on the criteria for determining early morning hypertension. Because of the dominant role of systolic blood pressure in the target organ damage of hypertension, the value of systolic blood pressure in the ambulatory blood pressure monitoring results is mostly used in the diagnosis of early morning hypertension. Commonly used clinical methods of determination now include.
(1) The average of systolic blood pressure 2h after waking up minus the normal value of systolic blood pressure 2h before waking up.
(2) The highest value of systolic blood pressure within 3h after waking up minus the immediate value of systolic blood pressure at waking up.
(3) The immediate value of systolic blood pressure at waking minus the last blood pressure value before waking.
(4) The highest value of systolic blood pressure minus the lowest value of systolic blood pressure before waking up within 3 h after waking up.
(5) The average value during the 2 h after waking minus the lowest value during sleep at night (average of 1 h including the lowest value);
(6) The rate of increase of systolic blood pressure every 60 min or 30 min after waking up.
There is another method of determining blood pressure that is considered to be more clinically valuable in both domestic and international studies, called the sleep-a-valley morning peak, which refers to the early morning blood pressure (average blood pressure within 2 h after waking up) minus the nighttime minimum blood pressure (average blood pressure during the 1 h in which the lowest blood pressure during sleep is located.) The Chinese Guidelines for the Prevention and Treatment of Hypertension published in 2010 use the above-mentioned measurement method, which specifies that: within 2 h after waking up The average of systolic blood pressure minus the lowest blood pressure during the night sleep (including the lowest value of the average of blood pressure for 1 hour), if the result is ≥ 35mmHg, then the diagnosis of early morning hypertension.
Second, early morning hypertension of cardiovascular damage
Studies have shown that, compared with other times of the day, the risk of cardiovascular disease attacks is 40% higher, the risk of sudden cardiac death is 29% higher, and the risk of various types of stroke is 49% higher during the period from 6:00am to 12:00am. Because of the consistency in the timing of early morning blood pressure elevation and the peak in cardiovascular events, many scholars have suggested that early morning hypertension be included as an independent risk factor for cardiovascular disease.
Early morning hypertension damages the heart first by exacerbating the process of myocardial hypertrophy, which is achieved mainly by increasing cardiac afterload and promoting arterial vascular sclerosis. The body mass index (BMI), an important indicator of myocardial hypertrophy and cardiac function, calculated by combining body surface area, is significantly higher in patients with early morning hypertension.
In addition, the QT interval was significantly longer in early morning hypertensive patients compared to those with hypertension alone, which reflects the greater damage to cardiac autonomic nerves caused by hypertension and predicts a significantly increased risk of malignant arrhythmias such as ventricular tachycardia and ventricular fibrillation. In addition to this, statistics also show that early morning hypertensive patients have more pronounced ST-segment depression in the ECG, suggesting an increase in myocardial ischemia.
Studies have shown that abnormally elevated blood pressure in the early morning can exacerbate the inflammatory response of blood vessels, which in turn induces plaque instability. Patients with hypertension with excessive blood pressure morning peaks have thickened carotid intima-media, increased urinary catecholamine excretion, and significantly higher levels of inflammatory markers compared to patients without blood pressure morning peaks.
In addition, hypertensive patients with early morning hypertension have a correspondingly increased risk of cerebrovascular events such as cerebral infarction and cerebral hemorrhage. The results of this study showed that the circadian rhythm of blood pressure disappeared in 84% of patients with hypertension combined with cerebral infarction, compared with 58% of patients with hypertension alone; 85% of patients with cerebral infarction combined with hypertension had abnormally high blood pressure in the early morning, compared with 55% of patients with hypertension alone, suggesting that the circadian variation of blood pressure and the presence of early morning hypertension are closely related to the incidence of cerebral infarction. is closely related to the incidence of cerebral infarction.
III. Treatment of early morning hypertension
For patients with early morning hypertension, the effect of lifestyle improvement on blood pressure control cannot be ignored. For this group of people, it is not recommended to get up or perform strenuous activities immediately after waking up in the morning, but to continue to lie in bed for a few moments or slowly get up on your side, pay attention to not smoking, not drinking alcohol, not drinking coffee and other sympathetic nerve stimulating drinks, avoiding emotional excitement, and strengthening exercise.
In terms of medication, the choice of the type of antihypertensive drugs and the time of medication is particularly important for patients with early morning hypertension. First of all, the choice of long-acting antihypertensive drugs and the combination of drugs is the basic principle, and it is recommended to use antihypertensive drugs with a trough-to-peak ratio greater than 50% and a smoothing index greater than 0.8, which can ensure that the blood pressure does not become too high in the early morning on the basis of a smooth lowering of blood pressure throughout the day. With regard to the timing of medication, several clinical studies have confirmed that bedtime medication is more effective in reducing early morning hypertension than morning medication.
In the specific choice of drugs, calcium antagonist drugs have the characteristic of relying on the basal blood pressure to lower the amplitude of the morning peak; because the over-activation of the renin-angiotensin-aldosterone system is an important mechanism of early morning hypertension, therefore, angiotensin-converting enzyme inhibitors (both named after XXpril) and angiotensin receptor antagonists (both named after XXsartan) are also good choices for the treatment of early morning hypertension. The better choice of drugs, such as enalapril, benazepril, perindopril, colesartan, valsartan, temisartan and candesartan, are recommended.
Regarding diuretics, they are not recommended alone in patients with early morning hypertension because they can alter the normal rhythmicity of blood pressure and the activation of the renin-angiotensin-aldosterone system, but they can be combined with other classes of drugs.
Adrenergic receptor blockers (e.g., metoprolol, bisoprolol, etc.) can also be used to treat early morning hypertension because of their sympathetic inhibition, but attention needs to be paid to their negative effect on heart rate when administered at bedtime.
Early morning hypertension is a common abnormal variant of 24-hour blood pressure, especially seen in the middle-aged and elderly population. Adequate knowledge of the characteristics and treatment of early morning hypertension by cardiovascular physicians is essential for the prevention of cardiovascular episodes during the early morning hours.