Cardioversion is the restoration of normal heart rhythm ( sinus rhythm ) in the presence of cardiac arrhythmias , usually atrial fibrillation , more rarely supraventricular or ventricular tachycardias or atrial flutter . A distinction is made between electrical cardioversion using a suitable defibrillator and medical cardioversion.
Cardioversion is indicated for tachycardiac (rapid) cardiac arrhythmias that impair the cardiac output. If the ejection rate is good, the application should be discussed depending on the type of cardiac arrhythmia and the symptoms. In patients with atrial fibrillation with few or no symptoms, cardioversion does not bring any clear prognostic improvement.
The principle of electrical cardioversion is similar to that of defibrillation . The activity of the heart muscle cells is to be synchronized by delivering a current surge. This prevents uncontrolled generation of excitation outside the actual stimulus generation system and enables orderly electrical activity, starting from the sinus node .
With electrical cardioversion, in contrast to defibrillation, the shock is delivered with a lower initial dose (usually 50–100 joules ). In addition, the electric shock is triggered by an EKG - this means that the device registers the R-wave in the EKG , i.e. the time of the contraction of the heart muscle cells that are still working synchronously, and delivers the shock at the same time. This will reduce the risk of ventricular fibrillation .
A patient who is awake is given a brief anesthetic to deliver the current.
In addition to electrical cardioversion, drug treatment can also be used. This has the advantage that no short-term anesthesia is necessary and the patient can under certain circumstances carry out the therapy himself ("pill in the pocket"). Commonly used drugs are amiodarone , flecainide and ajmaline . Overall, the success rate with pharmacological cardioversion is slightly lower than with electrical cardioversion (see table).
Both electrical and medical cardioversion are associated with an increased risk of embolism, e.g. B. a stroke . In addition, both procedures can in turn trigger cardiac arrhythmias.
Procedure for atrial fibrillation
The most common indication for cardioversion is symptomatic atrial fibrillation. The decision between electrical and medical cardioversion is made individually. If the onset of atrial fibrillation was not more than 48 hours ago, cardioverting can be carried out without anticoagulation . If the atrial fibrillation lasts longer than 48 hours, there is an increased risk of thromboembolic events. Therefore, an atrial thrombus must be excluded prior to cardioversion using TEE (transesophageal echocardiography, "swallowing echo"). Alternatively, anticoagulation can be performed for at least three weeks before and four weeks after cardioversion.
|Procedure||Success rate (sinus rhythm over 6 hours after cardioversion)|
The success rate of electrical cardioversion can be improved by the accompanying administration of antiarrhythmic drugs. In order to improve the long-term success of cardioversion, long-term drug therapy is also often prescribed.
Non-invasive cardioversion of supraventricular tachycardias
In the case of supraventricular tachycardia , non-invasive cardioversion can be attempted in stable patients. Various vagus maneuvers can lead to success here. An internationally recommended method is to use the Valsalva maneuver . It is also described in the literature as the most effective and safest method for stable patients with reentry tachycardia, both in emergency medicine and for self-treatment of patients, while a comparative study in 2013 and 2015 came to the conclusion that there was insufficient evidence for the effectiveness of the Valsalva - Maneuver to end supraventricular tachycardias is available. ("We did not find sufficient evidence to support or refute the effectiveness of VM for termination of SVT.") The success rates of cardioversion achieved in different studies vary greatly. They are between approx. 19% in clinical studies and up to over 50% in laboratory studies. A modification of the procedure that uses a different position, known as the Modified Valsalva maneuver , showed a significantly increased success rate of cardioversion in the study called the REVERT Trial : while with the traditional method in 17% of the Patient cardioversion was achieved, the rate at the changed position was 43%.
- T. Lewalter, L. Lickfett, JO Schwab, A. Yang, B. Lüderitz (2007) Emergency cardiac arrhythmias. German Doctor bl. 104 (17): A-1172 / B-1045 / C-997 PDF
- J. Reisinger, P. Siostrzonek (2005) Cardioversion of atrial fibrillation and flutter. J. Kardiol. 12: 3-11.
- A.J. Camm et al. Guidelines for the management of atrial fibrillation. European Heart Journal (2010) 31, 2369-2429. PDF ( Memento of the original from November 17, 2011 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- JR Ehrlich, SH Hohnloser (2005) Drug cardioversion of atrial fibrillation. Journal of Cardiology 94: 14-22.
- G. D. Smith, K. Dyson, D. Taylor, A. Morgans, K. Cantwell: Effectiveness of the Valsalva Maneuver for reversion of supraventricular tachycardia. In: The Cochrane database of systematic reviews. Number 3, March 2013, p. CD009502, doi : 10.1002 / 14651858.CD009502.pub2 , PMID 23543578 (Review).
- Andrew Appelboam, Adam Reuben u. a .: Postural modification to the standard Valsalva maneuver for emergency treatment of supraventricular tachycardias (REVERT): a randomized controlled trial. In: The Lancet. 386, 2015, p. 1747, doi : 10.1016 / S0140-6736 (15) 61485-4 .
- A. Appelboam, J. Gagg, A. Reuben: Modified Valsalva maneuver to treat recurrent supraventricular tachycardia: description of the technique and its successful use in a patient with a previous near fatal complication of DC cardioversion. In: Case Reports. 2014, 2014, S. bcr2013202699, doi : 10.1136 / bcr-2013-202699 .
- Gavin Smith: Management of supraventricular tachycardia using the Valsalva maneuver. In: European Journal of Emergency Medicine. 19, 2012, p. 346, doi : 10.1097 / MEJ.0b013e32834ec7ad .
- Gavin D Smith, Meagan M Fry et al. a .: Effectiveness of the Valsalva Maneuver for reversion of supraventricular tachycardia. In: Cochrane Database of Systematic Reviews. , doi : 10.1002 / 14651858.CD009502.pub3 .
- Modified Valsalva maneuver for supraventricular tachycardia , The Lancet 2015 on Youtube. The video shows the procedure for the modified Valsalva maneuver: When the pressure is increased for 12 s, the patient sits half upright (upper body in 45 ° position), while he is then lying flat with passively half-raised legs (legs in 45 ° position).