CHEST PAINGeneral Medical Emergencies 47(iii) Administer tenecteplase (TNK) as the lytic agent of first choice:
(a) give tenecteplase 30 mg (weight <60 kg), 35 mg (weight
≥60 to <70 kg), 40 mg (≥70 to <80 kg), 45 mg (≥80 to <90 kg)
and 50 mg (weight ≥90 kg) as a single bolus over 10 s
(b) tenecteplase is easiest to administer, safe given weight-based,
has greater fibrin specificity and with efficacy up to 12 h
(c) continue ECG monitoring for reperfusion arrhythmias.
(iv) Start unfractionated heparin by i.v. bolus 60 units/kg (maximum
4000 units), then i.v. infusion at 12 units/kg/h (maximum
1000 units/h) for 48 h in addition
(a) alternatively, give low-molecular-weight (LMW) heparin
such as enoxaparin 30 mg i.v. immediately, then 1 mg/kg
subcutaneously (s.c.) 12-hourly, but check your local policy.
(v) Other fibrin-specific lytic agents to consider if tenecteplase is
unavailable include:
(a) reteplase 10 units as a bolus over no more than 2 min,
followed after 30 min by a further 10 units bolus i.v.
(b) alteplase (rt-PA) 15 mg (15 mL) bolus, followed by an
infusion of 0.75 mg/kg over 30 min (to maximum 50 mg),
then 0.5 mg/kg over 60 min (to maximum 35 mg).
(vi) Give streptokinase (SK) 1.5 million units over 45–60 min in
100 mL normal saline if none of the above fibrin-specific agents
are available. The early infarct-related artery vessel patency rate is
less than with those agents
(a) avoid SK if it has been given between 5 days and 12 months
previously, or immediately after a severe streptococcal infection
(b) slow or stop the infusion if hypotension or rash occurs.
Restart the infusion as soon as they have resolved
(c) occasionally, severe hypotension and anaphylaxis may occur,
requiring oxygen, adrenaline (epinephrine) and fluids, etc.
(see p. 27).6 Percutaneous coronary intervention (PCI)
Organize primary percutaneous coronary intervention in preference to
thrombolysis, when it is available locally in less than 90 min of patient arrival,
or in less than 60 min if the chest pain onset was within previous 3 h.
(i) It is superior to thrombolysis, particularly in a high-volume
centre preferably with cardiac surgery capability.
(ii) It is preferred in cardiogenic shock, and if thrombolysis is
contraindicated.
(iii) Give thrombolysis with tenecteplase if the PCI will take longer
than the 60–90 min to organize.
7 Transfer the patient to the CCU following thrombolysis, or to the catheter
lab for PCI, with a doctor and nurse escort, and resuscitation equipment and
drugs available.