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Sunday, April 18, 2021

Thrombolytic Therapy (Thrombolysis): Acute Myocardial Infarction: Nursing Considerations

Thrombolytic Therapy (Thrombolysis): Acute Myocardial Infarction

Thrombolytic Therapy (Thrombolysis): Acute Myocardial Infarction

 Thrombolytics are given to treat some patients with acute Myocardial Infarction. These medications are administered IV according to a specific protocol. The goal of thrombolytics is to dissolve the thrombus in a coronary artery, allowing blood to flow through the coronary artery again, minimizing the size of the infraction and preserving ventricular function. Thrombolytics can be used as first-line therapy in facilities that lack the resource to perform PCIs. However, although thrombolytics may dissolve the thrombus, they do not the underlying atherosclerotic lesion. The patient may be referred for cardiac catheterization and other invasive interventions.

Thrombolytics dissolve all clots, not just the one in the coronary artery. Thus, they should not be used if the patient has formed a protective clot elsewhere, such as after major surgery of hemorrhagic stroke. Because thrombolytics reduce the patient's ability to form a clot, the patient is at risk for bleeding. Thrombolytics should not be used if the patient is haemorrhage or any type of bleeding disorder. All patient who receive thrombolytic medication are placed on bleeding precautions to reduce the risk for bleeding. This means reducing the number of punctures for inserting IV lines, avoiding intramuscular injection, avoid tissue trauma, and provide pressure for longer than usual after any puncture.

The effective way of thrombolytics should be administered as immediately as possible after the onset of symptoms that indicate an acute MI, commonly within 3 to 6 hours. They are administered to patients with ECG evidence of acute MI.

The thrombolytic agents used most often are alteplase and reteplase (r-PA, TNKase). Alteplase is a tissue plasminogen activator (t-PA) that activates the plasminogen present on a blood clot. An IV boluse dose is given and followed by an infusion. Aspirin and unfractionated heparin or LMWH may be used with t-PA to prevent another clot from forming at the area of the lesion. 

Administration of Thrombolytic Therapy

Indications of Thrombolytic Therapy

  • Chest pain for more than 20 minutes, uncontrolled by nitroglycerin.
  • ST-segment elevation in at least two leads that face the same area of the heart.
  • Less than 6 hours from onset of pain.
Absolute Contraindications

  • Active bleeding.
  •  Bleeding disorder.
  • Previous history of hemorrhagic stroke.
  • Previous history of intracranial vessel malformation.
  • Recent surgery or trauma.
  • Uncontrolled blood pressure.
  • Pregnancy.
Nursing Considerations for Thrombolytic therapy 

  • Avoid the number of times the patient's skin is punctured.
  • Avoid IM injections
  • Collect blood for laboratory tests when starting the IV line.
  • Avoid continual use of noninvasive blood pressure cuff.
  • Observe for acute dysrhythmias and hypotension.
  • Watch for reperfusion: resolution of angina or acute ST segments changes.
  • Assess for any signs and symptoms of bleeding: decrease in hematocrit and haemoglobin values, hypotension, tachycardia, bulging or oozing at invasive procedure sites, backache, muscle weakness, drop consciousness, complaints of headache
  • Treat major bleeding by discontinuing thrombolytic therapy and anticoagulants: apply direct pressure and notify the physician immediately.

STREPTOKINASE: 1.5 million units over 30-60 min i.v

ALTEPLASE (tPA):15 mg iv bolus then 0.75 mg/kg over 30 min (up to 50 mg) then 0.5 mg/kg over 60 min i.v ( up to 35 mg)

RETEPLASE (r-PA): 10 units + 10 units i.v. bolus given 30 min apart.

TENECTEPLASE ( TNK-tPA): Single i.v bolus:
  • 30 mg if <60 kg
  • 35 mg if 60 to <70 kg
  • 40 mg if 70 to <80 kg
  • 45 mg if 80 to <90 kg
  • 50 mg if >90 kg

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