Pacemaker (PM) and/or implantable cardioverter-defibrillator (ICD) implantation; generator change; PM lead insertion

Wilson Cui, MD PhD, Matt Dudley, MD 

PM/ICD Draft, 8/2014 

PROCEDURE

Pacemaker (PM) and/or implantable cardioverter-defibrillator (ICD) implantation; generator change; PM lead insertion

PATIENT DEMOGRAPHY

A patient may need a PM for a number of conditions. In general, symptomatic bradyarrhythmia or conduction defect is an unambiguous indication. In asymptomatic patients, high grade heart blocks, usually those with lesions below the atrio-ventricular (AV) node, are strong indications. Common indications for PM include:

  • Symptomatic bradycardia

  • Sick sinus syndrome,
Second degree (Mobitz II) AV block
  • 
Complete AV block

  • Bifascicular or trifascicular block

  • High grade block post myocardial infarction

The main indications for an ICD are for primary prevention of ventricular tachycardia or ventricular fibrillation (VT/VF) in patients at high risk of sudden cardiac death (SCD) due to VT/VF or for secondary prevention in those who had history of sustained VT/VF and/or SCD. These patients usually have underlying cardiac disease such as coronary artery disease, structural heart disease or various other cardiomyopathies. EF < 35% is generally the threshold for ICD. Other selected groups include those with:

  • Congenital long QT syndrome
  • Brugada syndrome

  • Hypertrophic cardiomyopathy

  • Arrhythmogenic right ventricular cardiomyopathy

A subset of patients are recommended to have biventricular (BiV) leads for cardiac resynchronization therapy (CRT) for low ejection fraction (EF <35%), NYHA class III-IV and QRS interval > 120ms.

Taken together, PMs and ICDs are types of cardiovascular implantable electronic devices (CIED). As such, patients who need CIED implantation may range from a robust endurance athlete, a transplant candidate in chronic heart failure, or a post-surgical patient with complete heart block.

PROCEDURAL DESCRIPTION

For ICDs, at least a single ventricular lead (with two defib coils) is inserted into the RV. For PMs, usually two leads, one for RA and one RV (“dual chamber”), are inserted. In some incidence, a single atrial lead is sufficient. For CRT, an additional LV lead is needed.

For the implantation of a new CIED, the preferred location is at the left upper chest. The proceduralist will infiltrate the skin with local anesthetic. The majority of proceduralists at UCSF will make the skin incision and perform dissection prior to getting venous access. A micropuncture needle is used to access the subclavian/axillary vein, using a combination of fluoroscopic and ultrasound guidance. After inserting the guide wire, the needle is exchanged for a dilator sheath. When difficulty is encountered (obtaining access or passing wires), a venogram is performed to ascertain the patency of the vein. Alternatively, venous access is done percutaneously prior to incision. This has the advantage of avoiding an unnecessary skin incision if the vein on that side is unfavorable for access.

Once the sheath(s) is in place, a lead with a rigid stylet is inserted. After confirm its position on fluoroscopy, the lead is secured in the endocardium using a screw system. . If more than one lead is planned, the RV lead is positioned first before the same steps are repeated for the RA lead. Typically the ventricular lead is secured in the RV apex, and the atrial lead is secured in the right atrial appendage. For BiV pacing, a lead is inserted into the coronary sinus in order to capture the LV. Then the outer sheath is peeled apart and removed. After the stylet is removed, the device company representative will check the sensing threshold and lead impedance. When satisfied, the external end of the lead is secured. Then a pocket is created and irrigated with antibiotic solution. The leads are connected to the generator, and the generator is placed in the pocket. After a repeat impedance check by the rep and one last fluoroscopic check, the incision is then closed. 

PRE-OPERATIVE ASSESSMENT

  • Standard ASA NPO guidelines should be followed for this elective procedure. 

  • A thorough assessment of the patient’s airway and respiratory status is essential since the airway will be far from the anesthesia provider with potential obstacles such as the fluoroscopic equipment and drapes. History of reactive airway disease, COPD, OSA, GERD, pleural effusion, or pulmonary edema from acute heart failure may affect the anesthetic management. 

  • The overall cardiovascular and functional status of the patient should be assessed. The patient may range from young and healthy to someone who has severely reduced ventricular function. The indication for the CIED is important. If the heart block is paroxysmal, associated symptoms should be noted, and back up pacing should be made available by the EP team. For PM generator change, it is important to note the patient’s underlying rhythm and whether there is AV conduction. Again, this may determine whether a temporary pacing lead is needed. 

  • Anti-platelet agents and anticoagulants use should be noted. Anti-platelet agents are usually not stopped. Warfarin is usually not stopped as long as the INR is not supra-therapeutic. Other agents are stopped at the proceduralist’s discretion. Regardless, their use may increase the risk of bleeding or hematoma during and after the procedure. At UCSF, the EP team usually postpones the procedure if the patient is on heparin infusion. 

  • Patient with chronic renal insufficiency or end-stage renal disease will need to have their electrolytes and fluid status assessed carefully. The team should be mindful of exposure to nephrotoxic contrast agents in patients with reduced GFR. Not infrequently, a venogram, usually of left upper extremity, is performed to delineate the vascular anatomy. 

  • Patients who suffer from chronic back or leg pain may not tolerate spending extended periods in a supine position without proper positioning, padding and analgesia. 

  • It is important to set proper expectation for the patient, who may say “just put me to sleep.” Most CIED placements or generator changes at UCSF are done under MAC, even conscious sedation by EP nurses sometime.

PRE-OPERATIVE PREPARATION 


  • Routine checks of anesthesia machine, emergency airway equipment, suction and resuscitation 
medications are imperative because access to additional equipment and anesthesia providers are limited. Usually, two infusion pumps and an invasive pressure transducer are available in each lab. At UCSF, a video laryngoscope (Glidescope) is located outside the EP control room. Contact the off-site anesthesia technician if you need any additional equipment. 

  • Blood products are usually not required, but a blood type and antibody screen should be current. 

  • Antibiotic usually 1 to 2 g of cefazolin is given prior to skin incision. 


ACCESS/FLUIDS 


  • At UCSF, the EP nurse will start a peripheral IV in the pre-op holding on the side of planned subclavian access (usually left arm). Additional PIV is usually not necessary. 

  • Anticipated blood loss is minimal and is usually associated with skin incision and the creation of a pocket.
  • Intravenous fluid should be given to maintain hemodynamic stability, but be mindful that a Foley catheter is not always present. Rarely, diuretic is administered in heart failure patients who is volume overloaded.

MONITORS

  • Standard ASA monitors: The EP staff will assist you in placing radiolucent ECG leads to ensure that they 
do not interfere with the fluoroscopic images or the rest of electrophysiology monitors. 

  • Invasive arterial monitor is indicated based on the patient’s cardiac status and the anesthetic plan, and is rarely needed when a light MAC is planned. However, it is reasonable in someone who 1) had a history of malignant arrhythmia and cardiac arrest, or 2) has severely reduced cardiac function AND defibrillation threshold (DFT) testing is planned. 

  • Temperature can be monitored with an axillary probe. A lower body forced air warmer is used. 

  • Urinary bladder catheter is usually not needed for straight forward cases. Discuss with the EP team for 
longer procedures, or when the patient is in heart failure. 


ANESTHETIC TECHNIQUES 


  • Anxiolytic premedication should not be given routinely in the holding area as most ambulating patients 
are expected to walk into the EP lab and sit up-right on the table while monitors and patches are placed. 

  • Broncho-dilator, anti-reflux medication and antacid should be given as indicated by the anesthetic technique and the patient’s co-morbidities. 

  • Vast majority of CIED procedures at UCSF are performed under MAC. The anesthetic goal is to provide analgesia and to ensure both patient safety and patient cooperation. Your anesthetic may range from a detailed pre-operative discussion, verbal reassurance, generous local anesthesia supplemented with minimal sedation in a motivated patient, to general anesthesia in an uncooperative patient with airway obstruction. Common pharmacological options include: 1) midazolam and fentanyl; 2) propofol infusion with intermittent fentanyl bolus; 3) Remifentanil infusion (in selected population); 4) Small doses of ketamine (patients who have significant cardiac disease or are at risk of airway obstruction). The most stimulating parts include the initial incision and the expansion of the generator pocket. 

  • Supplemental oxygen can be provided with nasal cannula with CO2 monitoring. Alternatives include oral/nasal airway, simple face mask, non-rebreather, or anesthesia mask with straps to provide PEEP (it is time to reassess your “MAC”). 

  • The emergence should be straight forward, which involves discontinuing the sedation, usually once the pocket is closed, and monitoring for any airway obstruction before leaving the EP lab. The EP staff will place the affected arm in a sling, and they prefer a relatively cooperative patient. 

  • Recovery of a patient after general anesthesia will be in the 4th floor PACU, while the patient who had MAC will be recovered in the EP holding room unless the anesthesia provider felt that a higher level of care (PACU or ICU) is necessary due to co-morbidities or intra-operative events, or if the length of recovery is expected to exceed the hours of EP staff. The patient will need to keep the arm to minimize the risk of bleeding. Postoperative pain is minimal with local anesthetic infiltration.
  • KEY PROCEDURE-RELATED POINTS
  • For new CIED or when there is a concern for the subclavian/innominate vein patency, the anesthesia provider will be asked to perform a venogram by injecting 10 mL of contrast followed by saline flush through the PIV on that side. For a patient with a history of contrast allergy, discuss the need for diphenhydramine and hydrocortisone with the EP team. 

  • If implanting an ICD, discuss with the EP team whether they plan to perform DFT testing by induce ventricular tachyarrhythmia. Anesthesia needs to be deepened prior to the test. Invasive monitor may be necessary if the patient has reduced EF. 

  • For generator changes, the device will be interrogated and reprogrammed prior to skin incision. If the patient has a complete heart block or underlying rhythm is severe bradycardia (i.e. pacemaker dependent), the EP team may need to place a temporary pacing lead, usually via the femoral vein. Alternatively, if the AV nodal conduction is relatively functional, it may be possible to disconnect one lead while the old generator maintains pacing via the remaining lead. Once the first lead is connected to the new generator, the second lead can be safely disconnected. 

  • Hemodynamic fluctuation is sometimes seen with tachy- or brady-cardia, and pacing. The changes are often self-limiting, but may require treatment in patients with low EF. 

  • POTENTIAL COMPLICATIONS 

  • Vascular injury from accessing the subclavian vein is possible but rare due to the open procedure. 
Bleeding from the generator pocket is another risk, and the risk increases with anti-thrombotic or anti- coagulation treatment. 

  • Transient arrhythmia, but can be sustained and hemodynamically significant. 

  • Pneumothorax. 

  • Pericardial effusion from lead perforation. Cardiac tamponade is a rare complication. This is usually indicated by persistent hemodynamic instability unrelated to the induced arrhythmia and refractory to routine vasoconstrictors and fluid. The EP team should be informed when this is suspected and can assist in placing additional invasive monitors and vascular access for resuscitation. Blood products should be ordered immediately. Consider reversing anticoagulation in consultation with the proceduralist. One or more of the femoral sheaths can be used for volume resuscitation. The management of effusion varies: 

  • “Wait-and-watch” approach when the effusion is small and self-limiting,
  • Emergent pericardial drain placement,
  • Rapid mobilization for surgical decompression of the tamponade.
  • SPECIAL ERGONOMIC CONSIDERATIONS
  • At UCSF, the anesthesia machine and cart are positioned to the right of the patient, as the proceduralists 
prefer to stand to the left of the patient for left subclavian access. 
Extensions on breathing circuit, oxygen supply, IV tubing, and infusion tubing are necessary to allow the unobstructed movement of the fluoroscopy equipment. Consider consolidating and securing monitors, circuits, and tubing such that they clear the C-arm, biplane and avoid tangling. Tourniquets and blue 
clamps are often useful. The patient’s arms will be secured, padded and tucked, limiting our access. One should consider attaching two pre-flushed infusion lines that can be used for anesthetic agents such as propofol or remifentanil, and vasoactive agents.
  • Hazards to the anesthesia provider
  • Equipment is in motion
  • Be aware of the c-arm when it is in motion as it can move quickly and endanger heads and shins and may snag loose wires and tubings.
  • Ionizing radiation
  • 
Consider time (limiting exposure), distance (inverse square law), and shielding (both garments and barriers) when in ionizing radiation environments. Particular attention should be granted to protecting the lens of the eye, thyroid, hematopoietic centers in long bones, and reproductive organs as these are particularly sensitive to ionizing radiation. The exposure is greatest as it exits the collimator (the part below the table) in path to the image intensifier (the part above the patient). However, scatter radiation is produced as the X ray encounters items in its path (the patient). Areas on the body that are often overlooked (“weak spots”) include neck, shoulder/arm pits, and back. Lead (radiation protective) garments should cover the neck to the knees and are designed to be worn when facing the source.
  • Magnetic fields
  • At UCSF, one of the EP rooms (EP1) is equipped with the Siemens Stereotaxis NIOBE® magnetic navigation system that can be used to manipulate wires and catheters in the patient’s body. The magnets are material and cannot be turned off, but the magnetic field is tempered when in the stored position. The magnetic field is not on par with the electromagnet used in MRI; however, MRI precautions are recommended.

DURATION 1.5 - 4 hours

REFERENCES

Anderson R, Harukuni I, Sera V. Anesthetic considerations for electrophysiologic procedures. Anesthesiol Clin. 2013;31(2):479-89.

Buxton AE, Lee KL, Fisher JD, Josephson ME, Prystowsky EN, Hafley G, for the Multicenter Unsustained Tachycardia Trial Investigators. A randomized study of the prevention of sudden death in patients with coronary artery disease. N Engl J Med. 1999;341:1882-1890.

Epstein AE, DiMarco JP, et al, American College of Cardiology Foundation; American Heart Association Task Force on Practice Guidelines; Heart Rhythm Society. 2012 ACCF/AHA/HRS focused update incorporated into the ACCF/AHA/HRS 2008 guidelines for device-based therapy of cardiac rhythm abnormalities: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines and the Heart Rhythm Society. J Am Coll Cardiol. 2013;61(3):e6-75.

Moss AJ, Hall WJ, Cannom DS, et al, for the Multicenter Automatic Defibrillator Implantation Trial Investigators. Improved survival with an implanted defibrillator in patients with coronary disease at high risk for ventricular arrhythmia. N Engl J Med. 1996;335:1933-1940.

Moss AJ, Zareba W, Hall WJ, et al, for the Multicenter Automatic Defibrillator Implantation Trial II Investigators. Prophylactic implantation of a defibrillator in patients with myocardial infarction and reduced ejection fraction. N Engl J Med. 2002;346:877-883. 

 

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This information is meant to serve as an educational resource. Clinicians should use their own professional judgment in the care of any individual patient as the guidance contained in this document may not be appropriate for all patients or all situations.