Acute M. I part 2

Streptokinase
(SK) is the usual thrombolytic agent.
Dose: 1.5 million units in 100mL 0.9% saline IVI over 1h.
SE: nausea; vomiting; haemorrhage; stroke (1%); dysrhythmias.
Any hypotension usually responds to slowing down or stopping the infusion.
Also watch for allergic reactions and anaphylaxis (rare).
Do not repeat unless it is within 4d of the first administration.

Alteplase
(rt-PA), followed by heparin, may be indicated if the patient has previously received SK (>4d ago) or reacted to SK.
Accelerated rt-PA has benefit if given within 6h, especially in younger patients with anterior MI.
Reteplase is given as 2 IV boluses 2h apart, and
tenecteplase is given by bolus injection (over 10sec), which in some cases may be an advantage.

Complications
Recurrent ischaemia or failure to reperfuse (usually detected as persisting pain and ST-segment elevation in the immediate aftermath of thrombolysis): analgesia, GTN, B-blocker, consider re-thrombolysis or angioplasty.
Stroke.
Pericarditis: analgesics, try to avoid NSAIDs.
Cardiogenic shock: see p788 and heart failure: see p786.
Right ventricular infarction
Confirm by demonstrating ST elevation in RV3/4, and/or echo. NB: RV4 means that V4 is placed in the right 5th intercostal space in the midclavicular line.
Treat hypotension and oliguria with fluids.
Avoid nitrates and diuretics.
Intensive monitoring and inotropes may be useful in some patients.

Acute myocardial infarction

Complications
Recurrent ischaemia or failure to reperfuse (usually detected as persisting pain and ST-segment elevation in the immediate aftermath of thrombolysis): analgesia, GTN, B-blocker, consider re-thrombolysis or angioplasty.
Stroke.
Pericarditis: analgesics, try to avoid NSAIDs.
Cardiogenic shock: and heart failure:

Thrombolysis
effective in reducing mortality if given early. Greatest benefit is seen if given <12h of the onset of chest pain, but some benefit up to 24h. The British Heart Foundation advises that the time from onset of pain to thrombolysis should be <90min (<60min if possible).
Indications for thrombolysis:
Presentation within 12h of chest pain with:
ST elevation >2mm in 2 or more chest leads or
ST elevation >1mm in 2 or more limb leads or
Posterior infarction (dominant R waves and ST depression in V1-V3)
New onset left bundle branch block.
Presentation within 12-24h if continuing chest pain and/or ST elevation.
Thrombolysis contraindications: (consider urgent angioplasty instead)
Internal bleeding
Prolonged or traumatic CPR
Heavy vaginal bleeding
Acute pancreatitis
Active lung disease with cavitation
Recent trauma or surgery (<2wks)
Cerebral neoplasm
Severe hypertension (>200/120mmHg)
Suspected aortic dissection
Previous allergic reaction
Pregnancy or <18wks postnatal
Severe liver disease
Oesophageal varices
Recent head trauma
Recent haemorrhagic stroke
Relative CI:
History of severe hypertension; peptic ulcer; history of CVA; bleeding diathesis; pregnancy; 18 weeks post-partum; anticoagulants.