High Blood Pressure

Understanding High Blood Pressure

circulatory system“High blood pressure” or hypertension is one of the most commonly seen diseases in a family doctor’s office. In B.C. 1 in every 3 people who pass away die due to a disease related to hypertension and its related complications. 

In the human body the heart functions as a pump. The heart pumps blood through blood vessels to supply all of the body with blood. In this process a certain blood pressure must be maintained for the blood to be circulated through the body properly. Blood pressure is the pressure exerted upon the walls of blood vessels when blood circulates. The unit for measuring blood pressure is “millimeters of mercury” (mmHg). The blood pressure measured will be different when the heart contracts and relaxes. When the heart contracts, blood pressure will increase (systolic); when the heart relaxes, blood pressure will decrease (diastolic). 

Risk Factors/Factors that determine blood pressure:

1. The heart: If the heart is damaged or dysfunctional it will not be able to properly pump blood through the blood vessels. For instance, during a heart attack the heart muscles are damage and so cannot pump blood properly causing a decrease in blood pressure. This is the most serious complication of a heart attack and is the most likely cause of death during a heart attack.  

2. The valves within the blood vessels: Under normal circumstance, when the heart contracts certain valves will “open” and when the heart relaxes certain valves will “close”. If the heart activity and the valves are not synchronized or when the valves have hardened (calcification) then the heart will need to work extra hard to push the blood through the body. In this case, blood pressure will increase. An example of this is aortic stenosis. 

3. The inner wall of the blood vessels:  Generally speaking, blood vessels’ walls have some flexibility and this helps to lessen the impact of changes in blood pressure. If the vessel walls lose their elasticity (e.g. connective tissue disorder due to genetic reasons or smoking) blood pressure will increase. 

4. Diameter of blood vessels: The larger the diameter of the blood vessel the lower the blood pressure will be within the vessel. The smaller the diameter of the blood vessel the higher the blood pressure. If you have experience with watering the plants in the garden, you will easily understand this concept. When you need the water to shoot farther from the hose, you will pinch the hose to increase water pressure as a result of the decrease in the diameter of the hose. There are many factors that can cause the narrowing of blood vessels:

  • Inborn:
    • Coarctation of Aorta (condition where the aorta is narrower than normal)
  • Developed
    • Obesity 
    • Lack of exercise 
    • Smoking 
    • Poor diet (e.g. many packaged food contains high sodium) 
    • Alcoholism 
    • Stress 
    • Hormone imbalance

Signs & Symptoms

High blood pressure usually does not display any signs or symptoms. Some patients may experience headache, dizziness, fatigue, nervousness, insomnia and nosebleed but most patients are only diagnosed when they have their routine checkup with their family doctor.  Even the first test cannot fully explain the problem so 2-3 tests are required for an accurate diagnosis. Generally the blood pressure between the right and left arms are the same. But in very rare cases some people will have different blood pressure in their arms. In such cases the arm with higher blood pressure should be taken as accurate. 

The chart below provides you with the numerical values of blood pressure for your reference. If you are a diabetic patient you should subtract 5 from all of the numbers. 

Category Systolic (mm/hg) Diastolic (mm/hg)
Ideal < 120 < 80
60+ years old < 130 < 85
Normal, slightly high 130-139 85-90
Slight hypertension 140-159 90-99
Hypertension 160-179 100-109
Severe hypertension ≥ 180 ≥ 110


When you have your blood pressure checked, you should also check for blood sugar and cholesterol level, urinalysis, kidney function, lung x-ray and eyes. 

Treatment

Common High Blood Pressure Medications: 

Bottle of pillsSome people can rely on exercise, losing weight, changing their lifestyle, or changing their diet to control their blood pressure. Although these changes are an important aspect of treatment without medication those changes alone may not be sufficient. Your doctor will determine if you need to take medication.

High blood pressure is a lifelong disease. If patients are required to take medication, they should take their medication according to their doctor’s instructions in order to enjoy a long healthy life. By controlling their high blood pressure, they will also prevent: damage to the heart vessels; heart attacks; stroke; blood clots; kidney failure; and other complications. 

Useful information about taking blood pressure medications:

  • Medications should be taken at the same time daily to be effective
  • If you tend to forget to take your medication(s), place the medication bottle(s) next to things you use daily, like breakfast plates
  • Most medications require up to 6 weeks to be fully effective, so be patient
  • Do not start a new medication before bedtime in case your blood pressure becomes too low over night
  • Long acting medications (such as CR, SR, CD, XL) should be taken whole on a daily basis; you should never cut the pills into smaller pieces
  • Taking a variety of low dose combination drugs rather than a single high dose drug is more effective and has less side effects
  • Many patients require 2 or 3 types of medications at the same time to effectively keep their blood pressure within the ideal range
  • Do not hesitate to use a few different types of medications, the most important thing is to protect the blood vessels and prevent complications from developing
  • Do not take / exchange other patients’ medications; everyone’s health and reactions to medications are different, so let your physician decide the best combination for you

Current medical treatment for high blood pressure can be categorized as: 

Diuretics (利尿劑)
Lowers sodium and water content in the body which lowers the volume of blood going through the heart and decreases blood pressure
Function: diuretic, eliminate edema, lower blood pressure
Appropriate for: congestive heart failure, edema 
Not appropriate for: gout, kidney failure 
Side effects: long term effects are on blood fat, blood sugar, uric acid, blood electrolyte imbalance, and especially loss of Potassium and Sodium which will require food consumption to replenish 
Examples: Thiazides (HCTZ); HCTZ/ Amiloride (Moduret); Idapamide (Lozide); Spironolactone (Aldactone); Loop diuretics (Furosemide) 

Beta blocker (乙型阻斷劑)
Function: lowers blood pressure, treats arrhythmia and angina, slows heart rate 
Appropriate for: post heart attack, teenager with fast heart rate 
Not appropriate for: people with slow heart rate, asthmatic patients, chronic obstructive pulmonary disease, and severe peripheral arterial disease  
Side effects: fatigue, slow heartbeat, dizziness
Note: people at the age of 60+ should not take this medication alone; these medications should not be discontinued abruptly as they need to be tapered off gradually.
Examples: Atenolol (Tenormin); Metoprolol (Lopressor SR); Bisoprolol (Monocor); Propranolol (Inderal); Acebutolol (Sectral); Pindolol (Visken); Nadolol (Corgard)

Calcium Channel Blockers (鈣離子阻斷劑)
Function: lowers blood pressure, treats angina and arrhythmias 
Appropriate for: angina, high blood pressure 
Not appropriate for: congestive heart failure 
Side effects: swelling in the feet, headache, flush 
Note: should always use the long acting (CD, SR, XL) version rather than the short acting CCB, only requires to be taken once a day. Some CCB will slow down the heart rate as well (eg. Diltiazem, Verapamil). Taking Beta Blocker at the same time may cause dizziness because of decreasing heart rate and lowering blood pressure too much.
Examples: Nifedipine (Adalat XL); Amlodipine (Norvasc); Felodipine (Renedil, Plendil); Diltiazem (Cardiazem CD, Tiazac); Verapamil (Isoptin SR)

ACEI-Angiotensin Converting Enzyme Inhibitors (ACE 抑制劑) 
Function: lowers blood pressure, protects the heart, blood vessels, and kidney. 
Appropriate for: diabetics, congestive heart failure patients, post myocardial infarction, enlarged left heart and proteinuria patients, 
Not appropriate for: Black people, Renal Artery Stenosis, Kidney function failure, women trying to get pregnant 
Side effects: severe coughing (especially in Asians) 
Examples: Ramipril (Altace); Perindopril (Coversyl); Captopril (Capoten); Enalapril (Vasotec); Fosinopril (Monopril); Lisinopril (Prinivil, Zestril); Quinapril (Accupril); Trandolapril (Mavik); Benazepril (Lotensin)

ARBs-Angiotensin II Receptor Blockers(血管收縮素II接受阻斷劑) 
Function: this type of medication has similar function as ACE inhibitors, it can protect the heart, blood vessel, and kidneys without causing coughing or other adverse reactions. This is a newer drug than ACE inhibitors. 
Appropriate for: Patients that cannot take ACE inhibitor 
Examples: Valsartan (Diovan); Irbesartan (Avapro); Candesartan (Atacand); Losartan (Cozaar); Telmisartan (Micardis); Eprosartan (Teveten)

Alpha Blockers (甲型阻斷劑)
Function: lowers blood pressure, treats enlarged prostate
Appropriate for: older men with an enlarged prostate 
Side effects: Postural hypotension and fainting, especially during first dose syncope. Drug dose should be increased gradually. Be extra cautious and move slowly when getting out of bed. Avoid driving at the first 24 hours. This drug should not be taken alone for the first time.  
Examples: Prazosin (Minipress); Doxazosin (Cardura); Terazosin (Hytrin)

Direct Renin Inhibitor (直接腎活素抑制劑)
This is one of the newest drug for lowering blood pressure 
Function: prevents the body from releasing angiotensin II which cause blood vessel to contract. As a result blood vessels will be relaxed, lowering blood pressure.  
Not appropriate for: Pregnant women and anyone that’s below the age of 18years old 
Examples: Aliskiren (Rasilez) 
 

Blood pressure Medication Combinations

These are drugs that combine two separate drugs into one pill to make it more convenient to use.

ACEI-Angiotensin Converting Enzyme Inhibitors + Diuretic  
Ramipril + HCTZ (Altace-HCT)
Perindopril + Indapamide (Coversyl-Plus)
Lisinopril + HCTZ (Zestoretic , Prinzide)
Quinapril + HCTZ (Accuretic)
Enalapril + HCTZ ( Vaseretic)

ARBS + Diuretic 
Candesartan + HCTZ (Atacand-plus)
Valsartan + HCTZ (Diovan HCT)
Losartan + HCTZ (Hyzaar)
Irbesartan + HCTZ (Avalide)
Telmisartan + HCTZ (Micardis Plus)

Beta blocker + Diuretic
Atenolol + HCTZ (Tenoretic)
Propranolol + HCTZ (Inderide)

With the current available blood pressure medication, blood pressure can be effectively controlled with the correct pairing of medication and lifestyle. For patients that have high blood pressure, you should always take your medication on time and you should provide your doctor with your blood pressures for their reference. Measure your blood pressure two to three times a week after resting for 10 mins.  
 
For hypertensive patients, the following factors may affect the effectiveness of the blood pressure medications: 

  • Did not take medications regularly or forgot to take medications
  • Medication dose is too low 
  • Combination of medications being taken is inappropriate 
  • Poor diet and excessive amount of salt in diet
  • Being overweight 
  • Smoking or excessive drinking 
  • Sleep apnea 
  • Psychiatric patients with other medications that interact negatively with hypertension drugs, e.g. Anti-inflammatory: NSAID, Cox-2 inhibitor, steroid drugs, contraceptive, decongestant, etc. 
  • Other disease that affects blood pressure, e.g. kidney failure, kidney blood vessel disease, adrenal tumor, pheochromocytoma, etc. 

Hypertension patients on long term medication for lowering blood pressure should always carry their list of medication in case of emergency. Most importantly they should keep in touch with their doctor and return for periodic checkups. With the joint effort of the patient and doctor, hypertensive patients’ can enjoy a healthy life with controlled blood pressure. 

Content by Dr. Thomas Ho, Family Physician