The risks and complications of out-of-the-OR cardiac procedures are related to the procedure itself, the patient's characteristics, and the usual anesthesia problems associated with care of the patient with poor cardiac function. Additionally there are risks associated with exposure to radiation secondary to the fluoroscopy used in these procedures.
Complications Related to the Anesthetic Management
Patients treated in the cardiology suite frequently have multiple and significant comorbidities such as coronary artery disease, valvular disease, heart failure, diabetes, renal insufficiency, obstructive lung disease, and morbid obesity. Consequently, anesthetic management is challenging, as almost all patients are ASA class III or higher. Many of the procedures can be performed under minimal or moderate sedation, but many others require deep sedation or even general anesthesia, often of prolonged duration.
Possible complications associated with anesthetic management include airway obstruction, hypoxemia, hypercarbia, aspiration, and hypotension. Studies suggest25 that a large percentage of patients undergoing electrophysiologic procedures (40%), require some type of airway intervention, from nasal/oral airway insertion to laryngeal mask airway (LMA) or endotracheal tube placement.
Also, of note are the effects of anesthetic agents on cardiac conduction. Volatile agents can affect the sinoatrial node automaticity, shorten cardiac potential, and prolong atrioventricular conduction time.
Factors such as increased patient weight and prolonged anesthesia time increase the chance of conversion from sedation to general anesthesia.
Complications Related to the Procedure
Nearly all procedures in the electrophysiology laboratory require percutaneous intravenous access with sizable catheters.
Potential complications related to the percutaneous access (common to most procedures) include bleeding, hematoma, pneumothorax, and occasional arrhythmias.
Some risks and complications are procedure specific:
Cardioverter defibrillators placement and testing requires the induction of ventricular arrhythmias which are recognized and converted by the devices. The effect of multiple trials of ventricular fibrillation with electrical conversion can produce hypotension during or immediately after testing.22,23,26
Intraoperative complications related to catheter-based radiofrequency ablation are relatively uncommon. They include esophageal rupture, atrial-esophageal fistula, pulmonary vein stenosis, thromboembolism, left atrial flutter, and atrial perforation.27,28
When using radiofrequency ablation for atrial fibrillation, the goal is to create a series of lesions in the atrium. The probe is set to deliver energy to a preset temperature and time, but the depth of the lesion is not easily controlled, hence the possibility of through the atrial wall injuries to adjacent structures. The esophagus sits behind the atria and as such can be injured leading to life-threatening mediastinitis.29
In this era of increased interventional cardiology, acute tamponade from cardiac perforation is encountered more frequently. Perforation of either the atrium or the ventricle is potentially fatal. The incidence of perforation is about 1% during PV isolation.30,31
Cardiac tamponade is life threatening. The rapid accumulation of blood in the pericardial sac leads to compression of all chambers as a result of increased intrapericardial pressure, which ultimately leads to a severely diminished filling of the heart. The clinical picture depends on the rate of fluid accumulation and the effectiveness of compensatory mechanisms. Therefore, the intrapericardial hemorrhage from cardiac perforation can become very dangerous, very fast.
Clinical findings include tachypnea and dyspnea, which are difficult to evaluate in the anesthetized/sedated patient. Physical findings are nonspecific. Tachycardia, hypotension and diminished heart sounds may be suggestive. Hypotension is almost always present and any change in blood pressure downward should raise the alert of the possibility of tamponade and myocardial perforation. A key finding is pulsus paradoxus, defined as an inspiratory systolic fall in arterial pressure of 10 mm Hg or more during normal breathing. This may be difficult to assess in the EP laboratory.
Echocardiography is of great importance in the diagnosis of pericardial tamponade. Among some of the echocardiographic signs, characteristic, although not very specific, are right atrial collapse during late diastole and right ventricle collapse during early diastole.32,33 Intracardiac echocardiography has been advocated as a method to prevent serious or fatal complications.
The treatment of cardiac tamponade involves drainage of the pericardial contents, preferably by needle pericardiocentesis, with the use of echocardiographic guidance.
Surgical exploration or intervention is indicated when complete control of the bleeding is in question or hemodynamic stability is not rapidly restored with pericardiocentesis alone.
The use of laser-assisted lead extractions techniques for chronically implanted pacemaker and ICDs leads are associated with potentially fatal complications from cardiac perforation, as well, and in addition to superior vena cava disruption and subclavian vein injury. The current literature cites mortality from laser-lead extraction ranging from 1.9% to 3.4%.15
Given the severity and acuteness of the pericardial tamponade secondary to perforation of the above-mentioned chamber/structures, it is not always possible to perform needle pericardiocentesis in a timely manner, and emergent surgical intervention may be required, sometimes with the help of cardiopulmonary bypass. One study15 suggests that laser-assisted lead extractions should be performed in the operating room in the presence of a cardiac surgery team in order to optimize the chances of survival in the event of complications.
In the view of the increasing number of patients with implanted cardiac rhythm management devices (pacemakers and defibrillators) requiring anesthesia for various procedures, the perioperative management of those patients may present a challenge for the anesthesiologist.
The American Society of Anesthesiologists has published guidelines regarding their management.34
The management of patients with implanted devices is a three-step process:
- 1. Preoperative management centers upon:
- • Establishing whether or not a patient has a cardiac rhythm management device (CRMD), by focused history, review of chest radiography (CXR), electrocardiogram (ECG), and physical examination
- • Defining the type of device by reviewing the manufacturer's card, interrogating it with a CRMD programming device, CXR, or querying the manufacturer's databases
- • Determining whether a patient is device dependent for antibradycardia pacing by patient history and device interrogation
- • Determining the device's function through consultation with a cardiologist or CRMD service
- Next the preoperative preparation should include the following steps:
- • Determine whether electromagnetic interference would be present during the planned procedure.
- • Determine whether reprogramming the device to asynchronous pacing mode or disabling the rate responsiveness function is needed.
- • Suspend the device's antitachyarrhythmia functions, if present.
- • Advise the use of bipolar electrocautery system if the patient is pacemaker dependent. If monopolar electrocautery must be used, recommend the use of short, irregular bursts.
- • Assure the availability of temporary pacing and external defibrillation equipment.
- The task force recommends changing to an asynchronous pacing mode for all patients who are pacer-dependent. This can be accomplished either by programming or magnet application.
- CAUTION: There is no reliable way to assess proper magnet placement.
- • Magnet application to a combined ICD/pacemaker may disable the tachyarrhythmia therapy function depending on the manufacturer of the device but not alter the pacing mode to an asynchronous mode. Therefore, in these devices only a consultant can change the pacing mode by using a device programmer.
- • Not all ICDs respond to magnet placement.
- • Some ICDs are permanently disabled by magnet placement.
- 2. Intraoperative management includes:
- • Managing potential sources of electromagnetic interference:
- • Electrocautery: Position the return pad in such a way that the current pathway does not pass through or in the vicinity of the device; suggest the use of short, intermittent bursts of cautery; suggest the use a bipolar cautery which reduces the current flow through the body.
- • RF ablation: Keep the RF current path as far away from the device as possible.
- • Lithotripsy: Avoid focusing of the lithotripsy beam near the generator, disable atrial pacing if the lithotripsy triggers on the R wave.
- • MRI is contraindicated for all devices.
- The external defibrillation pads should be placed as far away from the generator as possible in order to minimize damaging the device in case of emergency defibrillation. Before attempting emergency defibrillation or cardioversion in patients with disabled ICDs, the magnet should be removed to re-enable the tachyarrhythmia therapy function of the device. If the device does not deliver the appropriate shock then external defibrillation or cardioversion should be immediately performed.
- 3. Postoperative management
- The postoperative management should include interrogation of the device and restoration of the tachyarrhythmia therapy function of the device in the postanesthesia care unit or intensive care unit.34 Until the defibrillating function of the device is restored the function should be monitored with continuous ECG.
- No patient should be discharged from a monitored area until the device has been interrogated postoperatively.