Supraventricular tachycardia (SVT) is defined as an abnormally fast heartbeat. It may be associated with a number of medical conditions, like the following:
- hardening of the arteries;
- Wolff-Parkinson-White (WPW) syndrome;
- thyroid disease;
- emotional stress;
- chronic lung disease;
- the intake of too much caffeine;
- smoking tobacco;
- pulmonary emboli;
- alcohol abuse;
- cocaine abuse;
- certain drugs;
Signs of supraventricular tachycardia may include:
- fainting or near fainting;
- a fluttering in your chest;
- a pounding sensation in the neck;
- shortness of breath;
- rapid heartbeat.
For some people, most or all of their supraventricular tachycardia episodes may cease on their own, but, other suferrers require medical intervention.
Here is a comparison between amiodarone and adenosine, two drugs used for the treatment of SVT:
It is a potent antiarrhythmic drug which has a combination of calcium channel blockade, β-blockade, and class III antiarrhythmic effects and is useful for both ventricular and atrial-ventricular arrhythmia.
It is an iodine-containing compound with some structural similarity to thyroxine. It is sold under the brand names Nexterone, Cordarone, or Pacerone.
It is an antiarrhythmic agent that has several effects on the heart, including reduced automaticity of the sinoatrial node, depression of conduction at the atrioventricular node, and decreased atrial contractility.
This medication is sold under the brand names Adenocard and Adenoscan.
Amiodarone affects the rhythm of your heartbeats and is used to help keep the heart beating normally in patients with life-threatening heart rhythm disorders of the ventricles. It is also used to treat ventricular fibrillation or ventricular tachycardia.
Adenosine is used during a stress test of the heart as well as to treat certain types of abnormal heartbeats. Its effects only last for a couple of minutes.
Mechanism of Action
Amiodarone works by slowing the nerve impulses in the heart muscle, hence, affecting and restoring rhythm.
Adenosine works by increasing blood flow and dilating the arteries of the heart to help identify coronary artery disease.
Possible side effects of amiodarone include:
- loss of appetite;
- low blood pressure;
- slowed heartbeat (bradycardia);
- inflammation of the pancreas;
- severe skin reactions;
- awkward stance and walking;
- nerve damage (when taken for long periods of time);
- memory loss;
- problems with vision;
- inflammation of the liver;
- shaking and uncontrollable movement;
- overactive thyroid;
- trouble sleeping;
- increased cholesterol levels;
- low levels of thyroid hormone;
- sensitivity to the sun;
Possible side effects of adenosine include:
- swelling of the mouth, face, lips, tongue, or throat;
- fast or slow heartbeat;
- unusual hoarseness;
- problems swallowing;
- neck, throat, or jaw pain;
- trouble breathing;
- tightness in the chest or throat;
- shortness of breath;
- belly pain;
- a heartbeat which does not feel normal;
- chest pressure;
- peeling skin with or without fever;
- chest pain;
- blurred eyesight;
- drooping on one side of the face;
- trouble thinking;
- change in eyesight;
- passing out.
The initial dose is 1000 mg over the first 24 hours of therapy. The usual maintenance dose is 540 mg over 18 hours.
The recommended intravenous dose is 140 mcg/kg/min infused for 6 minutes.
Note – the initial dosage should be decreased to 3 mg in people with a transplanted heart, in those taking dipyridamole or carbamazepine, or in patients receiving the drug by central venous access.
Warnings & Precautions
Consult your healthcare provider before using this drug if you:
- are taking other medications;
- are sensitive to iodine;
- have an eye disease;
- have a thyroid disorder;
- have a heart disease;
- have a lung disease, such as bronchitis or asthma.
Do not take this drug if you have:
- severe low blood pressure;
- asthma or any other lung disease;
- other medical problems with your heart or heart rhythm;
- recently had a heart transplant.
Amiodarone may interact in a negative way with the following medications:
- Invirase (saquinavir);
- Fortovase (an antiretroviral drug);
- Covert (ibutilide);
- Norvir (ritonavir);
- Multaq (dronedarone);
- Omnel (itraconazole);
- Tikosyn (dofetilide);
- Invicek (telapravir);
- Perforomist (formoterol);
- Sporonax (an antifungal medication that is used to treat several fungal infections);
- Geodon (ziprasidone);
- Vfend (voriconazole);
- Haldol (haloperidol);
- Nizoral (ketoconazole);
- Pentam (pentamidine);
- Diflucan (fluconazole);
- Nebupent (an antimicrobial medication);
- Xalkori (crizotinib);
- Orap (pimozide);
- Lupron (leuoprolide);
- Juxtapid (Lomitapide);
- Varicept (nelfinazvir);
- Eligard (a medication used to treat breast cancer, prostate cancer, and uterine fibroids);
- Gleevec (imatinib);
- Crixivan (indinavir);
- Invega (paliperidone);
- Celexa (citalopram);
- Seroquel (quetiapine);
- Effexor (venlafaxine);
- Clozaril (clozapine);
- Pamelor (nortriptyline);
- Zocor (a lipid-lowering medication);
- Mevacor (lovastatin);
- Lipitor (atorvastatin);
- Cipro (ciprofloxacin);
- Biaxin (clarithromycin);
- Zithromax (azithromycin).
Adenosine may interact in a negative way with the following medications:
- Zofran (a medication used to prevent vomiting and nausea caused by cancer chemotherapy);
- Haldol (an antipsychotic medication);
- Phenergan (a neuroleptic medication and first-generation antihistamine).
Avoid or limit the intake of alcohol while taking these drugs.
Is It Safe During Pregnancy or Breastfeeding?
Avoid this drug if you are pregnant. Also, it should be stopped a few months before conception since it stays in the body for a long time. Moreover, avoid this drug if you are breastfeeding.
The use of this drug during pregnancy is recommended only if clearly needed and the benefit outweighs the risk. Also, this drug is not recommended during breastfeeding and a decision should be made to discontinue the drug or discontinue breastfeeding.
Bottom Line – Amiodarone vs Adenosine
Amiodarone produces a modest reduction of sudden deaths in high-risk patients and prevents the recurrence of life-threatening ventricular arrhythmias. It is currently regarded as the most effective antiarrhythmic drug available for the treatment of patients with both ventricular and supraventricular tachyarrhythmias. Also, it has very little negative inotropic activity and a low rate of ventricular proarrhythmia, making it beneficial for use in people with heart failure.
Adenosine is an antiarrhythmic agent and vasodilator which is used in the ICU to help diagnose atrial activity in atrial fibrillation, atrial flutter, or ventricular tachycardia and to convert paroxysmal supraventricular tachycardia to normal sinus rhythm.
According to a 2010 study done at the Department of Cardiology and Angiology, Germany, both drugs will enable effective and safe treatment of all tachycardias, bradycardias, SVTs, VT, ventricular fibrillation, ventricular flutter, and asystole.
Sources https://www.nejm.org/doi/full/10.1056/NEJMoa1514204 https://www.nejm.org/doi/full/10.1056/nejmoa0912613 https://www.ncbi.nlm.nih.gov/pubmed/10666663 https://www.ahajournals.org/doi/abs/10.1161/circ.100.19.2025