What causes stable angina?
Causes of stable angina include:
- Atherosclerosis: plaque buildup narrows coronary arteries, reducing blood flow
- Fixed stenosis: narrowing of coronary arteries limiting blood supply
- Demand ischemia: heart’s oxygen demand exceeds supply
What causes unstable angina?
Unstable angina is caused by
- Atherosclerosis with blood clot: plaque rupture in the coronary arteries can cause blood clots, severely reducing blood flow
- Thrombus: blood clot blocking blood flow
- Supply ischemia: reduced blood supply to the heart muscle
Comparison of symptoms
Stable angina is often triggered by exertion, stress, cold exposure, and CAD. Rest or medication will provide relief. This is usually predictable and consistent.
Unstable angina, on the other hand, may occur at rest or with exertion, worsens over time, and may not be relieved by rest or medication. It lasts over 20 minutes, may resolve, and then return.
Treatment of stable vs unstable angina
The main goals when treating stable angina are to increase the cardiac oxygen supply and to lower oxygen demand. For unstable angina, the priorities are to prevent infarction, maintain cardiac oxygen supply, and lower oxygen demand.
Medications
Stable angina:
- Nitrates
- β-blockers
- Calcium channel blockers
- Ranolazine
Unstable angina:
- Nitrates
- Β-blockers
- ACE inhibitors or ARB
- Antiplatelets (ASA)
- Anticoagulants (LMW heparin)
- May use thrombolytics after diagnostics
Non-drug therapy
Stable angina:
- Avoid triggers
- Decrease risk factors
- Consider PCI or CABG if medication is not successful
Unstable angina:
Unstable angina is a medical emergency that requires immediate intervention.
Nursing interventions
Stable angina:
- Assist client to sit or rest in semi-Fowler’s
- Assess vital signs, including pain
- Reduce anxiety and triggers
- Decrease oxygen demand
- Prepare for lab work, additional testing
Unstable angina:
- Administer medications as ordered
- Provide oxygen (when O2 SAT < 90% or signs of respiratory distress)
- Monitor for complications
- Provide client education
Client education
Angina symptoms may be different and more subtle in females. Educate clients on differences to avoid delay in care.
If a client is prescribed nitroglycerin, educate on the routes, usage, storage, and adverse effects. Instruct clients to call emergency responders if there is no improvement in angina 5 minutes, after 3 doses (15 min.) of nitroglycerin.
