pressure < 140 mmHg and diastolic blood pressure ≥ 90 mmHg. Isolated diastolic hypertension is common in people younger than 65 and is often accompanied by a rapid heart rate.
What is arterial compliance? What is Peripheral Resistance?
Arterial compliance is arterial elasticity. When the heart contracts, blood rushes into the aorta putting pressure on it, known as systolic pressure. If the arterial elasticity of the patient is poor, the degree of dilation of the large arteries decreases and the volume of the blood vessels decreases, resulting in an increase in systolic blood pressure.
Peripheral resistance refers to resistance to blood flow by arterioles. when the heart is in diastole, the large arteries elastically recoil as they expand, pushing blood into the arterioles. When the heart is at the end of diastole, there will still be a certain amount of blood remaining in the aorta, which will exert pressure on it and that is the diastolic pressure. If the patient's arteriolar resistance increases, blood will flow into the arteriole less. As a result, more blood will remain in the aorta and diastolic blood pressure will increase. In addition, the increased heart rate of the patient will shorten the diastolic period of the heart. Blood flow into arterioles will also be reduced. The aorta will also retain more blood and increase the diastolic pressure. There is usually no obvious abnormality in the elasticity of the large arteries in young and middle-aged people. However, a significant increase in peripheral resistance is often accompanied by an increase in heart rate. Therefore, they are prone to isolated elevated diastolic blood pressure.
What is the mechanism of action of commonly used antihypertensive drugs?
Antihypertensive drugs commonly used in clinical practice include angiotensin-converting enzyme inhibitors (ACEI), angiotensin receptor blockers (ARB), Ξ²-blockers, dihydropyridine calcium channel blockers and thiazides diuretics.
- Angiotensin-converting enzyme inhibitor (ACEI): It inhibits angiotensin-converting enzyme and blocks the production of the renin angiotensin II. It has no effect on heart rate but increases blood potassium levels. It can inhibit the synthesis of angiotensin II and reduce the level of angiotensin II.
- Angiotensin Receptor Blocker (ARB): It inhibits the angiotensin II receptor (AT1 type). It does not affect the patient's heart rate but increases his potassium levels. It inhibits the action of angiotensin II.
- Ξ²-blockers: It suppresses sympathetic nerve activity and cardiac contractility and slows the heart rate. It also raises the level of blood potassium. It reduces renin secretion and lowers the level of angiotensin II.
- Calcium channel blockers: It dilates blood vessels by inhibiting calcium channels on vascular smooth muscle cells. It reflexively activates the sympathetic nerves to increase the heart rate.
- Diuretics: These decrease volume overload by increasing urination. It does not affect the patient's heart rate but lowers blood potassium levels. It decreases the secretion of renin and the level of angiotensin II.
What are the pathophysiological characteristics of hypertensive patients in young and middle-aged patients?
Activation of the sympathetic nervous system: The biological marker of sympathetic nervous activation is increased heart rate, hypertensive patients in young and middle-aged are often accompanied by increased heart rate.
Activation of the renin-angiotensin system: hypertensive patients in young and middle-aged , especially those with risk factors such as abdominal obesity, dyslipidemia, and smoking, have higher plasma renin activity and angiotensin II levels than the elderly.
What antihypertensive drug should be preferred in patients with isolated elevated diastolic blood pressure?
ACEI and ARB inhibit the renin-angiotensin system. Ξ²-blockers inhibit the sympathetic nervous system.
If the patient's heart rate is >80 beats/min, Ξ²-blockers such as bisoprolol, carvedilol, and metoprolol are preferred.
If the heart rate of the patient is ≤80 beats/min, ACEIs (such as enalapril, perindopril) or ARBs (such as losartan, valsartan) are preferred.
Calcium channel blockers reflexively activate the sympathetic nerves. Diuretics can increase renin secretion and thereby promote the synthesis of angiotensin I and II. They are ineffective in the treatment of isolated diastolic hypertension.
In addition, studies have pointed out that about 200 patients who use Ξ²-blockers for 1 year will suffer from erectile dysfunction. ACEIs and ARBs are generally considered to have no adverse effects on sexual function, and some studies even suggest that they can improve.
