Screening for Heart Disease.
I really hate to see people spend money unnecessarily on all sorts of screening tests and exercises.
What i'd like to do with my blog is to give a run-down of screening tests that doctors use for different disease conditions. Hopefully, with more knowledge, the general public won't fall prey to all-inclusive yet very unnecessary screening tests.
Let's talk about heart disease.
Your heart basically never rests until the day you die. The heart and lungs have a great relationship, the heart receives deoxygenated blood from the body, pumps it out to the lung s for reoxygenation and the Oxygen rich blood comes back to the heart to be pumped out to the whole body. That's the simplified version.
Let's say you do a Ramly Burger-Kopi susu lemak manis-Kuey Tiaw goreng everyday diet, work till 11p.m, party till 5 a.m and repeat that. Add smoking, new onset diabetes and stress. You've got a great recipe for heart disease.
A little mantra my Senior residents used to say: Smoking + Diabetes + McD=Heart Attack on legs.
What are signs & symptoms of heart disease?
- Sudden death (65% of men, 47% of women)
- Heart attack
- Chest pain on exertion (angina)
- Chest pain at rest (Unstable angina)
- Shortness of breath on exertion.
- Dizziness, fatigue
- Erectile dysfunction i.e impotence
Of course, as you very well know, most people have no symptoms until it's too late.
What are the risk factors for heart disease?
- hypertension (high blood pressure)
- diabetes
- high cholesterol: TG, LDL & HDL levels are important
- smoking
- obesity
- stress
- male gender
- family history especially of heart disease in a 1st degree male relative <55>
- exposure to pollution with high proportion of particulates in the air
It's important that before a doctor carries out screening for heart disease that your medical history is taken and that history of any other illnesses in close family members is noted.
From there, your doctor can use the Framingham score or the Assign risk calculator to calculate your risk level of heart disease or death from heart disease risk within the next 10 years.
Risk paremeters assessed:
- Systolic blood pressure: >140 mmHg already confers increased risk
- Smoking: the more you smoke, the higher the risk
- Diabetes: having diabetes puts you at increased risk.
- Family history
- Triglyceride levels & LDL levels (Bad cholesterol)
- HDL (good) cholesterol levels
1. Resting ECG: a look at conduction of electricity across the heart.
2. Stress test: measures heart rate and changes in heart rhythm and blood pressure in response to stress (i.e exercise and increased demand). Sensitivity (pick up rate) of
- Treadmill test: sensitivity of 67%, specificity of 70%
- Nuclear test: sensitivity of 81%, specificity of 85-95%
- reference: American Heart Association journal, Circulation.
3. Pharmacologically exercised stress test: if someone is unable to physically walk/run, the heart can be challenged using certain medications.
4. Some centres may offer Coronary Calcium scoring via CT scan. The idea is basically that as you get older, more calcium is deposited in your blood vessel lining.
5. The best and "gold standard" to pick up heart disease is an Angiogram. However, this is normally done on clinical judgement: i.e if your history, risk profile and resting ECG is grossly abnormal, a doctor may opt immediately for an Angiogram as it is both diagnostic and therapeutic (may do balloon angioplasty/place stents to unblock the heart at the same time).
Blood tests
To assess risk of heart disease the following blood tests may be ordered:
- Fasting blood sugar
- Fasting serum lipids: Triglycerides, HDL, LDL and TC
- If needed, thyroid studies (associated with high TG)
1. Troponin I/Troponin T : specific to cardiac muscle but certain illnesses may elevate this level
2. CKMB
LDH is no longer used.
References:
Circulation, Fletcher et al. AHA Exercise Standards for Testing. 201:104:1694
http://www.americanheart.org/presenter.jhtml?identifier=4568
www.accessemergencymedicine.com/
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