**6. Post cardiac surgery ventricular arrhythmias**

These include the more common benign isolated ectopic beats or Non sustained ventricular tachycardia (NSVT) and the more dangerous ventricular tachycardia or ventricular fibrillation (VT/VF) which fortunately are less common. The incidence of sustained ventricular arrhythmias has been quoted at around 0.4 – 1.4% (53) to 0.7 – 3% (54). The benign rhythm changes including ectopic ventricular beats and NSVT can occur in up to 60% of patients (55) but are not known to portend the more malignant rhythms like VT/VF (56) nor do they portend any rise in mortality risk (55, 57) if no underlying structural heart disease is suspected. The mortality of sustained VT is high at around 50% in hospital and a further 10% die within 2 years. (53)

The risk factors for the occurrence of VT/VF seem to correlate with factors associated in general cardiology practice. Any underlying structural heart disease, prior myocardial infarction, reduced left ventricular ejection fraction or congestive heart failure increase the risk of life threatening ventricular arrhythmias. Immediate postoperative features which set off the rhythm disturbance include any hemodynamic instability, electrolyte or acid base disturbances, hypoxia, anemia, new onset ischemia etc. An occasional cause can be acute graft closure after bypass grafting. Any inotropes used in the postoperative phase can also be pro arrhythmic.

### **Treatment:**

Even though frequent ectopics and NSVT are considered benign it would be prudent to look for any reversible factors mentioned before in the acute phase. Lidocaine and pacing have been studied to suppress these rhythm disturbances but no actual benefit was observed. (53, 58) Sustained Ventricular arrhythmia is invariably quite unstable and quick remedial measures need to be instituted to treat the patient. Electrical cardioversion with 200 – 360 Joules is usually the first line option to convert the arrhythmia. If Direct Current cardioversion is not an option or if medications are preferred as per the clinical situation, various drugs like Lidocaine, Amiodarone, Procainamide can be considered. Emergency

Post Operative Arrhythmias 251

cause problems during the surgery. The cautery can inhibit the pacer and may cause inappropriate discharge of the ICD if the sensing function is not disabled. A comprehensive evaluation of the patient prior to surgery by an electrophysiologist is indicated. A magnet can be placed on top to disable the devices during the surgery so as to not cause any interference. Another option is to switch the pacer/ICD to asynchronous mode so that the cautery does not influence its function. However, patients need to be continuously monitored while the devices are in asynchronous mode as any malignant arrhythmias need

Arrhythmias complicate postoperative period after non cardiac surgery in up to 5 -20 % of the times. (69) Again, AF seems to be the most common arrhythmia making up about 68% of the documented arrhythmias. (8) Benign ventricular rhythms like ectopics or NSVT occur in up to 5 -25% of the patients and sustained VT is rather rare occurring in less than 1% of the

The rate of incidence after non-cardiac surgery also seems to depend on the type of surgery. Non vascular abdominal surgery, especially colorectal surgery seems more prone with rates of around 20%. The incidence seems increased after any instance of thoracotomy (10%) as well. In other instances the rate is around 0.01% after ophthalmologic surgery and 4% after

The risk factors seem to be similar to those implicated in post cardiac surgery including male sex, increased age > 70y, heart valve disease, prior history of arrhythmia, co existing asthma, congestive heart failure, and hypertension. (71) Post operative causes include electrolyte imbalances, hypoxia, and hypercarbia. (72) Sepsis seems to be a recurring factor implicated as a causative factor of arrhythmias. In fact all kinds of stress inducing causes like stroke, Gastrointestinal bleed, Pulmonary Embolism, Myocardial Infarction, pulmonary edema and others have been implicated. Some specific factors noted to cause postoperative arrhythmias also include anastomotic leak (77) or acute alcohol withdrawal. (69) Increased vagal tone due to anesthetic practices like laryngoscopy is also a risk factor for any

Apart from associated morbidity similar to post cardiac surgery arrhythmias, post non-

No large scale randomized trials validating the treatment of post non-cardiac surgery arrhythmias are available. However the management can be closely extrapolated from both post cardiac surgery treatment and non-surgical related general cardiology treatment protocols. Initial priority is to assess the physiological impact and stabilize the patient hemodynamically while searching for the specific causes that initiated the rhythm disturbance. One needs to rectify these issues while simultaneously initiating specific therapy to halt the arrhythmia. Specific treatment methods for individual rhythms are

In conclusion, postoperative arrhythmias, especially AF are common and are associated with significant morbidity and mortality but can be prevented to some extent. Further research is required to completely understand causes of such arrhythmias and to improve

cardiac surgery arrhythmias can also cause mortality of around 12 – 50%. (72, 73, 74)

similar to the approach already explained for post cardiac surgery arrhythmias.

to be treated via external defibrillator. (76)

cases. (70)

orthopedic surgery.

bradyarrhythmia.

**Management:** 

their prevention and treatment.

**8. Postoperative arrhythmias after non cardiac surgery** 

pacing via epicardial leads placed during surgery can be used sometimes to provide overdrive pacing to get the heart out of the arrhythmia. Emergency bypass surgery can be considered in some situations. (59) Readers are also referred to the American Heart Association (AHA) 2010 guidelines on advanced cardiovascular life support (ACLS) for dealing with unstable tachycardia. (75)

If the patient does survive and is back in sinus it is prudent to initiate them on long term beta blocker and ACE inhibitor therapy according to current ACC guidelines. For those who sustained VT/VF and have recovered, if there are no underlying risk factors mentioned prior, a cardiac electrophysiological study can be considered and an implantable cardiac defibrillator (ICD) is advised if there is any inducible VT or VF. If the patient is deemed to have an underlying heart disease that is unlikely to respond to medical therapy, an ICD may be indicated without electrophysiological study.
