Adenosine is an injectable antiarrhythmic drug indicated for acute treatment of Paroxysmal supra-ventricular tachycardia (PSVT).
Action of Adenosine
Adenosine is said to be useful and efficient in more than 90% of PSVT patients.
Paroxysmal supraventricular tachycardia
supra-ventricular tachycardia occurs when heart electrical system is not working properly. This leads to sudden heart beats. It can then slow down abruptly.
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Supra-ventricular tachycardia SVT can make heart rate suddenly goes above 100 b/m. This occurs either in resting or exercising state.
Symptoms of supraventricular tachycardia (SVT) can ocuur several times a day or once a year, lasts for a few minutes or occasionally for several hours, may be triggered by triggered by tiredness, caffeine, alcohol or drugs and starts for the first time in children and young adults. It may include:
- Angina
- fatigue, breathlessness or lightheadedness
- feel tired
- being sick
- some people don't have symptoms except for tachycardia
It’s usually used to treat arrhythmias, in which brief periods of rapid heart rate occur with the origin of the rhythm being above the ventricle) associated with accessory bypass tracts
Accessory bypass tracts: are remnants of the atrioventricular (AV) connections caused by incomplete embryological development of the AV and failure of the separation between the atria and ventricles.
As in Wolff-Parkinson-White syndrome (also known as a preexcitation syndrome), a condition in which strands of heart tissue formed during fetal development abnormally connect structures such as the atria and ventricles, bypassing normal conduction.
Wolff-Parkinson-White syndrome
Is a sub-group of patients with SVT. However, Pre-excitation (a short PR interval and a delta wave) is a finding on the resting ECG that is specific to WPW. (Sampson, 2016).
It's a congenital relatively common heart condition that causes the heart to beat abnormally fast for periods of time due to extra electrical connection in the heart.
Symptoms may only develop later in life and may be diagnosed with an ECG in healthy individuals with no symptoms or only occasional mild episodes of their heart racing; therefore WPW syndrome usually isn't serious.
However, it can rarely be life-threatening, when it occurs with atrial fibrillation, hopefully treatment can eliminate this risk.
Symptoms of Wolff-Parkinson-White syndrome are episodic varies from person to person, either on daily basis or even a few times a year, last for seconds, minutes or hours and triggered by strenuous exercise or drinking a lot of alcohol or caffeine or without identifiable trigger.
Symptoms of episode, you may experience symptoms such as:
- heart palpitations
- fatigue, breathlessness or lightheadedness
- Angina
- sweating
- feeling anxious
- finding physical activity exhausting
- fainting
Pharmacokinetics of Adenosine
- Distribution: rapidly throughout the body
- Metabolism: inside RBCs as well as in vascular endothelial cells.
Pharmacodynamics of Adenosine
- Depresses the pacemaker activity of the SA node.
- Reduce heart rate.
- Reduce the ability of the AV node to conduct impulses from the atria to the ventricles.
Dosing of Adenosine
Dosage forms of Adenosine
Injectable solution
- 6mg/2mL prefilled syringe
- 12mg/4mL prefilled syringe
Adult dosing of Adenosine
For adults and children weighing 50 kg (110
lb) or more:
- Initial: 6 mg by rapid peripheral I.V. bolus over 1 to 2 sec.
- If PSVT continues after 1 to 2 min: 12 mg given as rapid bolus and repeated in 1 to 2 min if needed.
- Don’t give single doses of more than 12 mg.
Pediatric dosing of Adenosine
For children weighing less than 50 kg:
- Initial: 0.05 to 0.1 mg/kg as rapid central or peripheral I.V. bolus followed by saline flush.
- If PSVT continues after 1 to 2 min: additional bolus injections are given, incrementally increasing dose by 0.05 to 0.1 mg/kg. Follow each bolus with saline flush.
- Injections continue until PSVT converts to normal sinus rhythm or until patient reaches maximum single dose of 0.3 mg/kg.
Geriatric dosing of Adenosine
- Initial: 6 mg IV bolui over 1-3 seconds (maybe given IO) followed by rapid flush with 20 mL NS.
- If no conversion within 1-2 minutes: give 12 mg IV bolus, repeat a second time if necessary
- 30 mg total
(Jones & Bartlett, 2015) along other references.
Adenosine: drug interactions
Adenosine has various drug interactions:
- Methylxanthines: antagonize the effects of adenosine, there may be a need for larger doses of adenosine.
Methylxanthines are alkaloids that can be found in high concentrations in tea, coffee, and chocolate. Theophilline, theobromine, and caffeine are the most popular.
- Dipyridamole and carbamazepine: potentiate the effects of adenosine, which may call for smaller doses of adenosine.
Dipyridamole, a non-nitrate coronary vasodilator that also inhibits platelet aggregation, is combined with other anticoagulant drugs, such as warfarin.
- Carbamazepine "an anticonvulsant": increases the risk of heart block.
Adverse reactions and side-effects of Adenosine
Adenosine many cause:
- facial flushing
- shortness of breath
- dizziness
- dyspnea
- chest discomfort
Nursing considerations for adenosine
- Valsalva maneuver should be attempted prior to adenosine administration in PSVT.
- Adenoscan isn't given to myocardial ischemia patients, due to the high risk of serious cardiovascular reactions.
- If solution isn’t clear, don’t give it.
- Give Adenocard by rapid I.V. bolus over 1 to 2 seconds. Slower delivery can cause:
- systemic vasodilation
- reflex tachycardia
- Inject adenosine directly into a vein to make sure drug reaches systemic circulation.
- If given into an I.V. line, give drug as close to insertion site as possible and follow with rapid saline flush.
- Don’t give single doses of Adenocard more than 12 mg.
- Monitor heart rate and rhythm, blood pressure, and respiratory status often during adenosine therapy.
- Be aware that at the time of conversion to normal sinus rhythm, arrhythmias (such as PVCs, premature atrial contractions, sinus bradycardia, sinus tachycardia, and AV block) may occur for a few seconds, but they don’t usually require intervention.
- Store adenosine at room temperature. Discard unused portion.
(Jones & Bartlett, 2015).
Nursing implications of Adenosine:
- Be aware that Adenosine many cause facial flushing, shortness of breath, dizziness, dyspnea and chest discomfort.
- Don’t give single doses of Adenocard that goes beyond 12 mg.
- Be aware that at the time of conversion to normal sinus rhythm, arrhythmias (such as PVCs, premature atrial contractions, sinus bradycardia, sinus tachycardia, and AV block) may occur for a few seconds, but they don’t usually require intervention.
- Store adenosine at room temperature. Discard unused portion.
Nursing care plan for Adenosine: Assessment
- Monitor vital signs frequently and ECG continuously during therapy.
- Assess apical pulse rate and blood pressure before giving the drug.
- Assess arrhythmia before and after therapy.
- Assess for signs of toxicity, drug interactions and adverse reactions.
- If ECG disturbances happen, withhold the drug, get an ECG strip, and inform physician immediately.
Nursing care plan for Adenosine: nursing diagnoses
- Decreased cardiac output related to arrhythmias or myocardial depression
- Risk for injury related to adverse reactions
- Deficient knowledge related to drug therapy
Nursing care plan for Adenosine: Patient's goals
- Cardiac output will improve as evidenced by vital signs and adequate urine output.
- Complications from adverse reactions will be diminished.
- The patient will verbalize an understanding of drug therapy.
Nursing care plan for Adenosine: Nursing management
- If the solution is cold, check for crystals that will appear, and in case crystals are obvious, delicately warm the solution to room temperature.
- Never utilize vague solutions.
- Give quickly for successful drug activity. Deliver straightforwardly into the vein in case possible.
- In case an IV line is used, inject the drug into the foremost proximal port and flush to guarantee that the drug was delivered into systemic circulation quickly.
- If ECG disturbances happen, withhold the drug, get a ECG strip, and inform physician immediately.
- Tell the patient that he may feel flushing or angina that keeps going for 1 to 2 minutes after the drug is injected.
- Take security precautions before administration since the patient may encounter a brief loss of awareness as the heart block increases.
- Notify the physician about unfavorable reactions.
Nursing care plan for Adenosine: Evaluation
- Patient maintains adequate cardiac output as evidenced by adequate tissue perfusion.
- Patient is free from serious adverse reactions.
- Patient lists the importance of drug adherence.
References:
- Jones & Bartlett. (2015). 2015 Nurse's Drug Handbook (13th ed.). Jones & Bartlett Learning.
- Lippincott Williams & Wilkins . (2013). Nursing pharmacology made incredibly easy! (3rd edition). Wolters Kluwer/Lippincott Williams & Wilkins Health.
- National health service. (2018, August 13). Wolff-Parkinson-White syndrome. https://www.nhs.uk/conditions/wolff-parkinson-white-syndrome/.
- National health service. (2021, April 27). Supraventricular tachycardia (SVT). https://www.nhs.uk/conditions/supraventricular-tachycardia-svt/.
- Sampson, M. (2016). Understanding the ECG. Part 5: Pre-excitation. British Journal of Cardiac Nursing, 11(3), 123–130. https://doi.org/10.12968/bjca.2016.11.3.123
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