General description of procedure, equipment, technique
The use of cardiac implantable electronic devices (CIED)—namely permanent pacemakers (PPMs); implantable cardioverter defibrillators (ICDs), transvenous and subcutaneous; devices for cardiac resynchronization therapy (CRT); and implantable loop recorders (ILRs)—appears to have increased over the last decade. This is mainly due to the expansion of indications and increasing life expectancy.
Complications and their management
Many children and young patients are receiving CIEDs at early ages of their lives. Also, many older patients are outliving the battery lives of their devices. As a result, an increased number of generator change-outs, lead replacements/revisions are being performed as well.
Expectedly, the numbers of complications associated with the CIED system are being noted. Specifically, issues pertaining to the lead, deemed as the weakest link in the system, are being increasingly reported.
However, we must emphasize that the complication rate has markedly decreased since the time of initial implants; especially with the use of smaller transvenous leads and the pectoral approach. Complications typically reported include bleeding, lead perforation, lead dislodgement or displacement, pericardial effusion with cardiac tamponade, subclavian arterial puncture, pneumothorax and hemothorax causing respiratory embarrassment, and device-related infections.
Operative complications, such as those mentioned, mandate emergent intervention. Additionally, management of CIED infections is extremely challenging. Thus, CIED-related complications need to be recognized and treated in a timely fashion to prevent patient morbidity and mortality.
Traditionally, complications are classified as acute, subacute, and chronic types. However, certain variables such as operator experience, and preoperative and postoperative conditions factor in outcomes and potential complications.
For instance, device implantations are largely performed in cardiac catheterization or electrophysiology laboratories using local anaesthesia and moderate conscious sedation. Medications used during these procedures could potentially cause serious reactions and complications as well.
Thus, immediate and late outcomes depend on parameters that are prevalent before and during CIED implantation. In this chapter, we discuss the more pertinent CIED complications, classified in a simple form as in Table 1; and their individual management with special emphasis on device infections and indications for lead extraction.
i) Bleeding/hematoma formation/device erosion
The exact incidence of significant bleeding and hematoma is unknown. It is, however, estimated to be between 2.0% and 5.0%. In a systemic review of implantation related complications of ICDs and CRTs in randomized clinical trials, van Rees et al. reported the incidence of pocket hematoma in 2.2% of nonthoracotomy ICD recipients and 2.4% in the CRT recipients.
The true incidence of pocket hematoma, however, more than likely is higher as most randomized trials reported only those hematomas requiring evacuation and drainage. In a study by Wiegand et al., high-dose heparin, combined aspirin, and thienopyridine treatment after coronary stenting, and low operator experience were independent predictors with a hazard ratio [HR] of 4.2, 5.2, and 1.6, respectively, for development of postoperative hematoma.
Interestingly, in patients with atrial fibrillation, postoperative high-dose heparin substantially increased the hematoma rate without reducing the rate of embolic events within the first month post-CIED. Likewise, in patients with the mechanical aortic valves requiring anticoagulation, a minimalist strategy of withholding oral anticoagulation resulted in a similar quality-adjusted life expectancy (QALE) when compared to an aggressive strategy of perioperative subcutaneous low molecular weight heparin or intravenous heparin.
Although the latter aggressive approach provided greater QALE for patients with mechanical mitral valves who were at higher risk of stroke, the benefit was small. Elimination of postoperative use of low molecular weight heparin substantially reduced hematoma rates as well.
More recently, studies have indicated the safety of performing ICD implantation on maintenance oral anticoagulant dosing when compared with heparin “bridging.” This would suggest that continuation of oral anticoagulation within acceptable international normalized ratios (INRs) of around 2.0 was safe.
Most pocket hematomas may be treated conservatively with local compressive dressing. Exploration is indicated if the hematoma expands significantly; compromising skin capillary perfusion leading to wound dehiscence and necrosis.
Significant pain is another indication of pocket site exploration. When this is done, the wound should be thoroughly cleaned and inspected for any active bleeders.
We recommend topical thrombin within the pocket, especially if the patient is on oral anticoagulation. However, surgical intervention in the postoperative period is associated with a much higher risk, up to 15 fold, to pocket and device infection. We strongly discourage attempting to drain a hematoma by needling the pocket percutaneously.
Inadvertent injury to the lung resulting in pneumothorax can be prevented by using the extrathoracic venous system. For instance, accessing the cephalic vein by a surgical cut-down, or accessing the axillary vein under fluoroscopic, venography, and ultrasound guidance reduces this possibility. Data derived from many large ICD and CRT trials indicate that incidence of pneumothorax related to implantation has fallen to 0.9%.
We routinely perform an upright chest x-ray postprocedure for all patients in whom the subclavian vein was accessed, and if multiple attempts were made to access the axillary vein. Irrespective of the venous access point, all patients undergo a chest radiograph the day following implantation.
Most small pneumothoraces, without respiratory or hemodynamic compromise, may be observed closely. They typically resolve spontaneously.
If there is no evidence of further increase in the size and severity of the pneumothorax with follow-up chest radiographs over 24-48 hours; and if the patient has no symptoms or signs of respiratory distress, it is safe to discharge the patient home. These patients can be followed up in as an out-patient in 7-10 days for further clinical and radiologic evaluation of pneumothorax.
On the other hand, if the pneumothorax is moderate to large in size (Figure 1) and results in pain, respiratory distress, and hemodynamic compromise, it needs to be treated with insertion of a chest tube to drain it. Hemothorax is a relatively rare complication as it results from major vascular injury. Most hemothoraces require surgical drainage.
iii) Pericardial effusion/tamponade
This is an uncommon complication with the exact incidence unknown. The occurrence of pericardial effusion is typically caused by lead perforation, and can be an early or late presentation.
Interestingly, asymptomatic lead perforation with subsequent pericardial effusion appears more common. In a study by Hirschl et al., a very small percentage of subjects were detected to have a pericardial effusion on CT scans. Most pericardial effusions were small, not requiring further intervention. Patients with large effusions and effusions causing hemodynamic compromise need to undergo emergent pericardiocentesis.
iv) Diaphragmatic stimulation
This occurs when the right ventricular lead penetrates through the right ventricular wall and the pacing output captures the diaphragm. In most cases, interrogation of the device would show noise on the right ventricular lead electrogram.
As diaphragmatic stimulation in the immediate postprocedure phase indicates lead perforation, the ventricular lead must be promptly repositioned. In cases of CRT device implantations, diaphragmatic stimulation may also indicate phrenic nerve capture of pacing energy delivered through the coronary sinus (CS) lead.
This may occur if the CS lead gets displaced from its original implant site; but it may also occur due to proximity of the phrenic nerve occurring in only certain positions that could not be tested at the time of implantation. In such cases, use of newer multipolar leads and options of different pacing configuration may help resolve the issue rather than repositioning the lead.
We discourage administration of any muscle relaxing agents at CRT device implantation, so that phrenic nerve capture resulting in diaphragmatic contractions may be easily identified.
v) Inappropriate connections
For appropriate functioning of CIED, it is absolutely important that all components are correctly connected. A loose set screw connection may result in inappropriate and/or total failure of sensing and pacing.
High lead impedances due to a make-break circuit may be indicative of this complication, which may be further confirmed by a good quality chest x-ray film (Figure 2) and/or high quality cinefluoroscopy in multiple views. Suboptimal or wrong connections of defibrillator leads in cases of ICDs and CRT-Defibrillator (CRT-D) devices may cause total failure or inappropriate shocks.
Complete malfunction of the device appears to be extremely rare. However, the exact incidence would be difficult to determine. These numbers are obtained from a few voluntary registries and the U.S. Food and Drug Administration (USFDA) that receives reports on devices with severe malfunction mandating explanation.
ii) Lead malposition and perforation
In this section we discuss various aspects of lead dislodgement, displacement, fracture, insulation damage, migration, and perforation. Issues related to device nonfunctioning and inappropriate functioning are also discussed.
Acute lead dislodgement/displacement usually occurs within 24 to 48 hours after CIED implantation. In patients dependent on pacing, the ventricular lead dislodgement may result in fatality.
The incidences reported in single center and large multicenter trials vary from 1.8% to 4%. The risks of lead dislodgement are higher with the coronary sinus leads and passive fixation leads.
Dislodgement rate also depends on operator experience, implantation techniques in terms of appropriate positioning and fixation mechanism, securing leads with anchoring sleeves, etc. The anchoring sleeve though needs to be sutured to fibro-fascial tissue with nonabsorbable suture material; the ligature must not be very tight; and extreme care needs to be taken when the ligature needs to be cut or removed during the operative procedure.
In the situations described, the lead insulation may breakdown resulting in device malfunction. Figure 3 shows lead insulation breakdown at the level of the sleeve due to tight ligature or operative injury. In a patient who is 3 weeks after PPM implantation, the ventricular lead could not capture even at the highest programmable output, and the lead impedance had dropped dramatically to low levels since implantation.
In our experience, the routine practice of applying an arm immobilizer to minimize traction on the lead has shown to minimize acute lead dislodgement.
Lead dislodgement, if significant, can be easily detected on chest radiography. Figure 4 and Figure 5 show dislodgement of atrial and ventricular leads, in posteroanterior and lateral views of a routine chest radiograph performed post implantation.
Micro-dislodgement of a lead, on the other hand, may not be appreciated radiographically, even with multiple views. Failure to sense or pace, inappropriate lead impedance on device interrogation, and frequent ectopy are some indicators of lead dislodgement. Inappropriate mode switches due to sensing of far-field R waves indicate dislodgement of the atrial lead along the tricuspid annulus and requires repositioning.
We recommend immediate repositioning of the dislodged lead or its removal and replacement by a new lead if the active fixation mechanism is deemed to have failed. Severe tricuspid regurgitation may pose a challenge in securing a stable and optimal position, which sometimes could be higher on the interventricular septum for right ventricular lead.
In such situations, it is mandatory to choose an active fixation lead. For ICDs, dislodgement of the right ventricular lead may cause significant issues with appropriate sensing and therapy of ventricular tachycardia (VT) and ventricular fibrillation (VF).
The incidence of early postoperative lead perforation is very rare. In a large Mayo clinic series comprising 4,280 patients who underwent PPM implantation, the incidence of detection of pericardial effusion related to lead perforation was 1.2%. By multifactorial analysis, use of temporary pacemaker, helical screw leads, and steroids were identified as predictors of lead perforation with relative risks (RRs) of 2.7 (95% confidence interval (CI) 1.4-3.9), 2.5 (95% CI 1.4-3.8,), and 3.2 (95% CI 1.1-5.4), respectively.
Most immediate postoperative lead perforations are those that occurred during, but not recognized at implantation. In this situation, progressive accumulation of blood in the pericardial space may result in pain, pericardial effusion, and even cardiac tamponade necessitating emergent drainage. Abnormal pacing and sensing parameters usually with marked difference in unipolar and bipolar sensing, and inappropriate lead impedance on device interrogation occurs with lead perforation.
With advancement in operator experience, device technology, aseptic precautions and prophylactic antibiotics, the infection rate related to CIED implantation has reduced considerably. The true incidence of CIED infections is considered to be fairly low at less than 5%.
Presence of diabetes mellitus, heart failure, and renal insufficiency has now been recognized as risk factors for CIED infections. The occurrence of infection correlates positively with fever within 24 hours before the implantation procedure (adjusted odds ratio (OR) 5.83, 95% CI, 2.00 to 16.98), use of temporary pacing before the implantation procedure (OR, 2.46; 95% CI, 1.09 to 5.13), and early reinterventions (OR, 15.04; 95% CI, 6.7 to 33.73), and correlates negatively with implantation of a new system (OR, 0.46; 95% CI, 0.24 to 0.87) and antibiotic prophylaxis (OR, 0.4; 95% CI, 0.18 to 0.86).
In most cases, periprocedural erythema and inflammation around the incision indicative of superficial infection can be treated safely with systemic and topical antibiotics. Most CIED infections occur from Staphylococcus aureus, or epidermidis, and rarely from other organisms such as Enterococcus, Propionibacter, Pseudomonas, and Proteus species.
In our clinical experience, we have not seen Candida infection in the acute setting. Even in the acute or subacute (less than one month of postimplantation period) setting, when the deep pocket is involved, and if there are no signs of improvement then total removal of the entire system is necessary. In one series, up to 5% of CIED needed to be removed within a short postoperative period.
We recommend vigilant observation for the next 3 months, since most CIED infections, with or without evidence of endocarditis and vegetations on the leads and/or valves, become apparent then.
i) Inappropriate shocks
Inappropriate shocks may occur due to an inherent arrhythmic substrate that the recipients of the ICDs and CRT-D devices have or as a result of device malfunction. Inappropriate shocks typically due to supraventricular arrhythmias, including sinus tachycardia have been reported in up to 25% of patients with defibrillators.
Figure 6 shows inappropriate shock due to atrial fibrillation with a rapid ventricular rate that the device misdiagnosed as VT/VF. Figure 7 shows an example of inappropriate shock due to T-wave oversensing, where double counting of the R and the T waves met the criteria to define sinus rhythm as VT.
Appropriate programming, increased use of dual-chamber devices, and discriminators that are seen in newer devices can help prevent this morbid situation. One may, however, have to treat supraventricular arrhythmias aggressively with antiarrhythmic drugs in addition to routine atrioventricular nodal blocking agents, and even ablation of the culprit supraventricular arrhythmias or ablation of the atrioventricular node.
One of the major device/lead related causes of inappropriate shocks is lead coil/conductor fracture. In the latter situation, it is mandatory to remove the lead from the shock circuit of the device.
This may require insertion of a new lead and capping and abandoning the culprit lead, or total extraction/removal of the culprit lead and insertion of a new lead. If one can determine with absolute confidence that the issue lies with only the rate/sense component and not the high voltage shock coils, one may insert a new rate sensing lead, keeping the high voltage coils in the circuitry.
Other causes include electromagnetic interference (EMI) causing electrical noise, inappropriate sensing, and malfunction. Inappropriate shocks due to EMI from surgical cautery may be prevented by application of magnet over the ICD site during surgical procedure.
ii) Twiddler’s syndrome
This was first described in 1968. It refers to malfunction of the device due to patient manipulation of the pulse generator. Obese patients with abdominal devices are more likely prone to this syndrome. A recommended solution for prevention of this unusual complication is minimizing size of pocket and suturing devices to fascia.
iii) Tricuspid regurgitation
The exact incidence of this complication is unknown since most data are from retrospective studies. In one such retrospective study from the Mayo clinic, 41 patients, who also had CIED, underwent tricuspid valve replacement due to severe tricuspid regurgitation. However, transthoracic echocardiography diagnosed valve malfunction due to the lead in only five patients.
Lead extraction is performed for a variety of reasons, including infection, lead failure or dysfunction, and lead recall. The strongest indication for this procedure continues to be CIED associated infections.
Severe pocket infection with erythema, swelling, scab formation over the incision site (Figure 8) in a patient with clinical features of infection and/or sepsis, and of course, erosion of the CIED device through the skin (Figure 9) are obvious reasons for the total removal of the CIED system. Injury to the lead, directly or indirectly, accounts for the other causes.
Recall of leads is another emerging entity to consider lead extraction. The Sprint Fidelis (Medtronic) lead and more recently the Riata lead (St. Jude Medical) have been recalled due to issues with coil and insulation failure leading to inappropriate shocks.
Figure 10 shows a recording of intracardiac electrogram demonstrating inappropriate shock in a device with a Sprint Fidelis lead. Typically, upon device interrogation, multiple short nonphysiologic V-V intervals, noise, and high impedance of the ventricular lead with many detected VT episodes where either the therapies are delivered or diverted many times, are observed.
Rarely are significant thrombotic symptoms due to venous obstruction, especially with multiple leads, an indication for lead extraction. Table 2 shows the common indications for which lead extraction is performed.
Performing lead extraction is an extremely challenging and at times, laborious process. Implanted leads, over time, get fixed to myocardium by virtue of fibrosis, thereby encasing the lead. Traditionally used techniques including traction on the proximal lead were associated with major complications.
Prior to proceeding with lead extraction, each patient should be evaluated for lifelong consequences, implications of the procedure, and eventual outcomes. Transesophageal echocardiography plays an important role in the assessment of the size, shape, and friability of vegetation, along with the presence of intraatrial or intraventricular communications; for example, patent foramen ovale, atrial septal defect, or ventricular septal defect in patients with vegetations and endocarditis requiring extraction.
Figure 11, Video 1 shows a large vegetation on the RV lead during a transesophageal echocardiogram. Dependency of the patient on CIED should also be determined prior to lead extraction.
Another important factor that sometimes may not be accounted for is age. The current belief is to proceed with extraction in younger patients versus a more conservative approach in the elderly.
In the past, thoracotomy with lead removal was performed in patients with vegetations even smaller than 10 mm in diameter; or after failed attempts with transvenous lead removal. However, more recently, transvenous lead extractions are being increasingly performed.
But several observations favor lead extraction to abandonment. Among several methods of lead extraction, laser-assisted lead extraction using the CVX-300 (Spectranetics) laser system and the SLS II (Spectranetics) laser sheath has been shown to be safe and effective.
However, many times even for successful extraction of ICD leads, standard intravascular countertraction method using flexible polypropylene or Teflon sheaths (Cook Pacemaker Corp.) may be sufficient. In a study by Kantharia et al., successful lead extraction by intravascular countertraction method was performed in 47 patients without any serious complication or mortality.
Patient’s age, sex, or history of coronary artery bypass graft surgery did not significantly affect extraction time. Most of the procedures were carried out safely in the EP laboratory.
Leads that are abandoned are more difficult to extract and when this is attempted, the process is associated with increased complications. This suggests duration of the implant is important. Additionally, it is also important to consider the fragility or tensile strength of each lead prior to proceeding with extraction or abandonment.
Antibiotics are mandated prior, during, and after the planned procedure regardless of whether extraction is performed surgically or otherwise. The duration and choice of antibiotics vary according to the offending organism.
Surgical methods are preferred when vegetations are greater than 2 to 3 cm in size; leads inadvertently placed in the left chambers or in cases where leads have exited the venous system. Surgery with an open thoracotomy is also necessary when significant scarring and fibrosis is anticipated, especially when multiple chronic leads need to be removed with the total system, vegetations, and necrotic material (Figure 12, Figure 13).
In recent times, multiple centers have reported success with a transvenous approach and no significant pulmonary embolism, post procedure. Thus, at high-volume centers with experienced operators, a transvenous approach can be safely performed for vegetations <2 cm; whereas, for vegetations >2 cm, decisions regarding approach should be individualized.
Transvenous lead extraction may be associated with complications, such as damage to the tricuspid valve, subclavian vein laceration, hemothorax, pocket hematoma, and fracture of the lead tip. Hence, these should be performed at centers with surgical back-up.
In appropriate patients, complete removal of all hardware is strongly recommended, along with adjunctive antimicrobial therapy. This approach may be modified if the patient is at risk of procedural complications and has a short life expectancy.
The increasing trend in CIED-related complications can be, to a large extent, attributed to increasing implantations. It is hence imperative to take all possible measures to prevent these complications, and develop the ability to treat these complications and even when necessary extract these systems safely and effectively.
Over the past few years, operator experience has improved resulting in fewer complications. Furthermore, complications associated with lead extraction have decreased significantly as well.
Newer techniques for extraction of leads including use of locking stylets, sheaths, snares, retrieval baskets, and countertraction mechanisms have somewhat facilitated these complex procedures. Precautions prior, during, and post procedure, along with antibiotics and the adequate experience of the implanting physician are crucial in implantation techniques, thereby improving safety and efficacy of the procedure. Lastly, we encourage all implanting physicians to report all CIED-related complications in an effort to develop a registry to help future generations.
What’s the evidence?
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