Unstable angina

unstable-angina

Unstable by angina is a clinical syndrome that is characterized by new-onset or rapidly worsening angina (Crescendo angina), angina on minimal exertion or angina at rest in the absence of myocardial damage.

Acute coronary syndrome is a term that encompasses both unstable angina and myocardial infarction.

Pathogenesis: Fissuring of atheromatous plaque which is associated with thrombosis or vasospasm (supply led ischemia).In contrast stable angina is related to a fixed obstruction and usually precipitated by an increase in myocardial oxygen demand.

ECG: In patient with unstable angina or partial thickness myocardial infarction the ECG shows ST/T wave changes and T wave inversion; the T wave changes are sometimes prolonged.

Characteristics:                                 

  • More severs.
  • More frequent ( 3 or more attacks per day)
  • More prolonged.
  • Provoked by less exertion or even at rest.
  • Less relived by usual remedial measure.
  • Referred to new sites.
  • Unusual new symptoms.

Unstable angina: Risk stratification:

High risk Low risk
Clinical Post infraction angina. Recurrent pain at rest. Heart failure. No history of MI. Rapid resolution of symptoms.
ECG Arrhythmia.

ST depression.

Transient ST elevation.

Persistent deep T wave inversion.

Minor or no ECG changes.
Biochemistry Troponin T >0.1 µg/L Troponin T < 0.1µg/L

Management:

[A] Initial treatment:

  1. a) Immediate hospitalization.
  2. b) Bed rest.
  3. c) Aspirin: 300 mg followed by 75-325 mg daily long term and clopidogrel 300 mg followed by 75 mg daily for 12 months.
  4. d) Β-blocker: Atenolol 50-100 mg daily or metoprolol 50-100 mg 12 hourly.
  5. e) Calcium channel blocker: Nifedipine (with β blocker).
  6. f) Anticoagulant therapy with heparin (i/v infusion of unfractional heparin with does adjusted thrombin time, or as subcutaneous low molecular wt. heparin)

[B] If pain persists or recurs: Intravenous nitrates- GTN 0.6-1.2 mg/hour or isosorbide dinitrate 1-2 mg/hour.

[C] If medical treatment fails: Emergency coronary angiography should be done then PTCA or CABG.

Reference:

  1. Davidson’s Principle and Practice of Medicine, 21st edition.
  2. Wikipedia the free encyclopedia.

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