Transesophageal Echocardiography as a Monitoring Tool during Transvenous Lead Extraction—Does It Improve Procedure Effectiveness?

Background: Transesophageal echocardiography (TEE) is a valuable tool for monitoring the patient during transvenous lead extraction (TLE), but the direct impact of TEE on the effectiveness and safety of TLE has not yet been documented. Methods: The effectiveness of TLE and short-term survival were compared between two groups of patients: 2106 patients in whom TEE was performed before and after TLE and 1079 individuals in whom continuous TEE monitoring was used. The procedure-related risk of major complications was assessed using a predictive SAFeTY TLE score. Results: The patients monitored by TEE were characterized by older age, more comorbidities and higher SAFeTY TLE scores (6.143 ± 4.395 vs. 5.593 ± 4.127; p = 0.004). Complete procedural success was significantly higher in the TEE-guided group (97.683% vs. 95.442%, p < 0.01). The rate of serious complications in the TEE-guided group was lower than the predictive SAFeTY TLE score—a reduction of 28.75% (p < 0.05). Periprocedural mortality in the TEE-guided and non-TEE-guided groups was zero vs. six deaths (p = 0.186). Short-term survival was comparable between the groups. Conclusions: Transesophageal echocardiography as a monitoring tool during transvenous lead extraction provides valuable results—higher rates of complete procedural success and a reduced risk of the most severe complications, thus preventing periprocedural deaths.


Introduction
Transvenous lead extraction (TLE), as a method for managing complications related to cardiac implantable electronic devices (CIED), has been evolving since the 1990s and is now widely used in hospitals all over the world. The European Heart Rhythm Association (EHRA) report indicates that more than 9000 TLEs are performed annually at over 350 centers [1][2][3].
Lead extraction techniques involve manual traction or laser energy to dissect and remove lead from the cardiovascular system. Given the potential for serious complications related to cardiac tear or venous injury, it is crucial to constantly improve the safety of the procedure being performed. TLE belongs to relatively safe invasive procedures -the percentage of major complications range from 0.9 to 4.0%, unfortunately, procedural deaths (up to 1.86%) are still reported [4][5][6][7][8][9][10][11][12][13][14].
Both European and American guidelines published in 2017 provided more refined recommendations regarding the safety of TLE procedures. It is therefore recommended to perform TLE in an operating room or a hybrid operating room, preferably under general anesthesia, with direct systemic blood pressure monitoring via an indwelling arterial catheter, with a cardiothoracic surgeon available and with the continuous monitoring of the patient using transesophageal echocardiography (TEE) or intracardiac echocardiography (ICE) [13,14]. This study therefore sets out to assess the impact of continuous TEE monitoring on the effectiveness and safety of TLE. In order to estimate TLE-related risk, we use a previously devised SAFeTY TLE score to determine the probability of developing major complications during the procedure [15].

Study Population
This post-hoc analysis used clinical data of 3185 patients who underwent transvenous lead extraction between March 2006 and January 2020. Between the years 2006 and 2015, there were 2106 lead extractions with concomitant transthoracic echocardiography (TTE) and transesophageal echocardiography before and after the procedure, without intraprocedural monitoring. Between June 2015 and January 2020 there were 1079 lead extractions entirely under TEE guidance. All the procedures were performed at two different centers by the same experienced operator in both cases.

Lead Extraction Procedure
Lead extraction procedures were performed using mechanical systems such as polypropylene Byrd dilator sheaths (Cook ® Medical, Leechburg, PA, USA), mainly via the subclavian approach on the side of the implanted device. If technical difficulties arose, a different vascular access and/or additional tools such as Evolution (Cook ® Medical, Bloomington, IN, USA), TightRail (Spectranetix Colorado Springs, CO, USA), lassos and basket catheters were utilized. Laser cutting sheaths were not used. In the non-TEE-guided group, extraction procedures were performed by an experienced TLE operator and qualified nurses in an electrophysiology lab, in patients under general anesthesia and sedation. In the TEE-guided group lead extractions were performed by a team consisting of the same experienced TLE operator, with a second operator who had experience with pacing therapy, acardiac surgeon, anesthesiologist and echocardiographist. Procedures were performed in an operating room or in a hybrid operating room, in patients under general anesthesia, with continuous invasive blood pressure monitoring. Indications for TLE and type of periprocedural complications were defined according to the 2017 HRS Expert Consensus Statement on Cardiovascular Implantable Electronic Device Lead Management and Extraction as well as the European Lead Extraction ConTRolled (ELECTRa) study: a European Heart Rhythm Association (EHRA) Registry of Transvenous Lead Extraction Outcomes [13,14].

Transesophageal Echocardiographic Monitoring
Transesophageal echocardiographic monitoring was performed using the GE Vivid 3, Vivid 4, and Vivid S 70 systems, as well as the Philips iE33 ultrasound machine equipped with transesophageal probes for 3D and 4D imaging. All images were stored in a digital memory for extended analysis after the procedure. Leads ) visualizing three leaflets of  the tricuspid valve, right ventricular long axis, RVOT, and right ventricular cross-sections. Sometimes,  if necessary, nonconventional imaging planes were used for better visualization of the structures. TEE monitoring was conducted in three phases: preprocedural, intraprocedural and postprocedural. The study started after patient intubation with the insertion of an echocardiographic probe down the esophagus. All study phases were performed during the same extraction procedure. In the preprocedural phase, we evaluated the lead position, degree of fibrous encapsulation, lead-to-lead adhesions, unaccounted-for structures in the leads, as well as the function of the tricuspid valve and the pericardium. The intraprocedural phase was performed during the extraction procedure, taking into account direct pulling on the cardiac walls, obliterating the right ventricular lumina and their effect on the hemodynamic status of the patient. Furthermore, we observed pulling on other leads, detachment and dislodgement of fibrous tissue or vegetation fragments, and the separation of pericardial layers. The postprocedural phase included an evaluation of tricuspid valve function, remnants of masses removed during TLE (vegetations, fibrous tissue), and the abnormal accumulation of fluid in the pericardial sac.

Estimating the Number of Major Complications Using the SAFeTY TLE Score
The SAFeTY TLE score assesses the risk of the occurrence of major complications related to TLE and takes into account the following parameters: sum of dwell times of extracted leads (threshold value ≥16.5 years), hemoglobin level in the blood (threshold level <11.5 g/dL), female gender, the number of previous CIED-related procedures and age below 30 years at first CIED implantation. The numbers of expected major complications in the two groups were determined using the SAFeTY TLE score calculator, an online tool available at http://alamay2.linuxpl.info/kalkulator/ [15].

Statistical Analysis
The Shapiro-Wilk test showed that most continuous variables were normally distributed. For uniformity, all continuous variables are presented as the mean ± standard deviation. The categorical variables are presented as a number and percentage. The significance of differences between groups was determined using the nonparametric chi 2 test with Yates correction or the unpaired "U" Mann-Whitney test, as appropriate.
The Kaplan-Meier method was used to calculate the probability of mortality-free survival in patients divided into two groups according to the presence or absence of TEE monitoring during TLE. The log-rank test, including complete and censored data, was used to test for differences between the survival curves. A two-tailed p value < 0.05 was considered statistically significant. Statistical analysis was performed with Statistica version 13.3 (TIBCO Software Inc., AP Palo Alto, CA, USA).

Clinical Characteristics of the Study Population
TEE-guided patients were older and more frequently had comorbidities (Charlson comorbidity index 4.972 ± 3.756 vs. 4.434 ± 3.538; p < 0.001) compared with non-TEE-guided individuals. Those in the TEE-guided group more often had lower left ventricular ejection fraction (LVEF) and higher New York Heart Assiocation (NYHA) functional class. Moreover, TEE-guided patients were characterized by lower blood levels of hemoglobin and were more frequently treated for chronic renal failure. The groups did not differ significantly in the incidence of other diseases such as diabetes mellitus, coronary artery disease, previous sternotomy or chronic atrial fibrillation, whereas arterial hypertension was more common in non-TEE-guided individuals (60.779 vs. 53.012; p < 0.001

Outcomes of Transvenous Lead Extraction
A total of 5258 leads were extracted, including 1760 in the TEE-guided group and 3498 in the non-TEE-guided group. In both groups, the number of extracted leads per patient was similar on average, 1.631 ± 0.719 vs. 1.661 ± 0.761; p = 0.477. The TEE-guided group differed from the non-TEE-guided group by the older age of the extracted leads (sum of lead dwell times: 15.466 ± 13.960 vs. 11.876 ± 11.004 years; p < 0.001), more frequent removal of ICD leads (31.603% vs. 25.309%; p < 0.001), less frequent extraction of left ventricular leads (11.307% vs. 14.008, p < 0.05) and abandoned leads (8.804% vs. 15.527%; p < 0.001). Technical difficulties during the procedures and additional tools for lead removal were more common in the TEE-guided group (23.818% vs. 15.907%; p < 0.001 and 6.951% vs. 5.128%; p < 0.05, respectively), whereas modification of venous access was more frequently necessary in non-TEE-guided individuals (5.558 vs. 1.668; p < 0.001). The duration of the procedure, measured by various parameters (skin-to-skin, sheath-to-sheath and mean duration of one lead extraction), was significantly longer in the TEE-guided group.
Complete procedural success was significantly higher in the TEE-guided group (97.683% vs. 95.442%, p < 0.01), whereas clinical success was comparable between the groups. In the periprocedural period, there was not a single death among TEE-guided patients, compared with six deaths (0.285%) in the non-TEE-guided group (p = 0.186) ( Table 3).

Assessment of the Risk of Major Complications Using the SAFeTY TLE Score
The total score on the SAFeTY TLE scale was higher in the TEE-guided group (6.143 ± 4.395 vs. 5.593 ± 4.127; p = 0.004). The higher risk of major complications in this group was associated with longer lead dwell times and lower levels of hemoglobin (p < 0.001). According to the simulation, the risk of cardiac and venous perforation was significantly higher in individuals undergoing intraprocedural TEE monitoring: 1.898 (95% CI: 1.664-2.132) vs. 1.630 (95% CI: 1.472-1.788); p = 0.002. The SAFeTY TLE score yielded an expected number of 21 and 34 perforations in the superior vena cava (SVC), right atrium (RA) and right ventricle (RV) during TLE in the TEE-guided and non-TEEguided group, respectively (Table 4).

Assessment of the Risk of Major Complications Using the SAFeTY TLE Score
The total score on the SAFeTY TLE scale was higher in the TEE-guided group (6.143 ± 4.395 vs. 5.593 ± 4.127; p = 0.004). The higher risk of major complications in this group was associated with longer lead dwell times and lower levels of hemoglobin (p < 0.001). According to the simulation, the risk of cardiac and venous perforation was significantly higher in individuals undergoing intraprocedural TEE monitoring: 1.898 (95% CI: 1.664-2.132) vs. 1.630 (95% CI: 1.472-1.788); p = 0.002. The SAFeTY TLE score yielded an expected number of 21 and 34 perforations in the superior vena cava (SVC), right atrium (RA) and right ventricle (RV) during TLE in the TEE-guided and non-TEE-guided group, respectively (Table 4).  The incidence of major complications did not differ significantly between the TEE-guided and non-TEE-guided group: 21 cases (1.946%) vs. 39 cases (1.852%), including 15 (1.390%) vs. 33 (1.567%) cases of hemorrhagic pericardial or pleural effusion and six (0.556%) vs. six (0.3285%) cases of significant damage to the tricuspid valve (Table 5, Figure 2).  Detailed analysis of major complications in both groups showed that, in TEE-guided patients, the number of major complications associated with hemorrhagic pericardial or pleural effusion was six less than predicted by the SAFeTY TLE score-a reduction of 28.57% (p < 0.05). In the non-TEE-guided group there were 33 major complications vs. 34 predicted by the risk calculator (Table 6). Table 6. Comparison of number of major complications (perforations; SVC, RA, RV), calculated vs real complications, according to data from Tables 4 and 5. Abbreviations: superior vena cava (SVC), right atrium (RA) and right ventricle (RV); for the SAFeTY-TLE score, see Table 4.

Discussion
A search of the literature revealed few small observational studies and case reports that addressed the usefulness of transesophageal echocardiography for monitoring the patient during transvenous lead extraction [16][17][18][19][20]. This is the first study to compare the impact of TEE guidance on the effectiveness and safety of transvenous lead extraction procedures in two large groups: 1079 patients undergoing continuous TEE monitoring and 2106 patients with echocardiographic assessment before and after the procedure. The current study found that the use of continuous echocardiographic monitoring of lead extraction procedures resulted in a significantly decreased frequency of most dangerous complications related to cardiac and vascular damage.
As is well known, age of the lead at the time of extraction is the most important risk factor for complications related to TLE. This parameter is incorporated into scoring systems for the prediction of technical difficulties during the procedure and for the stratification of the risk of major complications related to TLE [10,15]. Intraprocedural transesophageal echocardiography permits visualization and evaluation of structural changes caused by leads with long dwell times, thus facilitating navigation during the extraction procedure. In the initial phase of the procedure, it is very important to visualize lead adhesion to cardiac and vascular structures. TEE facilitates the imaging of lead adhesion to the walls of the superior vena cava, tricuspid valve and walls of the right atrium and right ventricle, as well as assessing lead-to-lead adhesion and the degree of fibrous tissue growth around lead tips in the cardiac wall ( Figure 3). The information provided by an echocardiographist during the procedure permits the extractor to take appropriate precautions during the freeing of the lead from the encapsulating fibrous tissue and pulling on the cardiac walls to remove the lead in its entirety.
The imaging of lead adhesions permitted us to determine the site of potential cardiac injury. An analysis of traction force and winding of soft tissues during dilator maneuvers warned the extractor of the risk of possible damage, which undoubtedly affected the procedure strategy, resulting in a reduction in the number of the most severe complications: cardiac and vascular perforations (Figures 4 and 5).
A more detailed description of the echocardiographic findings in patients with TEE monitoring during TLE was presented in an earlier report [21].
The SAFeTY TLE score of 21 for wall perforations in the TEE-guided group was significantly higher than the number of actual complications (n = 15), which corresponds to a reduction of 28.571%; 95% CI (9.249-47.893); p = 0.028 in the risk of perforation. In the non-TEE-guided group, the score for perforations was 34 compared with the actual incidence of 33 complications, which confirms the accuracy of the calculation and significant benefits of using TEE as a monitoring tool during the extraction procedure. The decreased risk of damage to the superior vena cava, right atrium and right ventricle documented in patients undergoing TLE under continuous TEE guidance is certainly a result of implementing such an approach. This study supports evidence from previous small observational studies [16][17][18][19][20].  Apart from providing very important information on the challenges of lead extraction, continuous TEE monitoring allows for a prompt reaction to the occurrence of directly life-threatening complications: pericardial tamponade, hemorrhagic pleural effusion and tricuspid valve injury ( Figure 2). It is interesting to note that a reduction in the most severe TLE complications was encountered in patients at potentially higher procedural risk. This study shows that patients with TEE guidance had older leads and were generally at higher risk of major complications according to the SAFeTY TLE score (6.143 ± 4.395 vs. 5.593 ± 4.127; p < 0.001) compared with non-TEE-guided procedures, which were characterized by more technical difficulties and prolonged operative time. Furthermore, patients with TEE guidance were older and presented with more comorbidities. Despite poorer clinical characteristics, complete procedural success was significantly higher in patients with TEE guidance (p < 0.01). The achievement of such a high rate of TLE effectiveness was also a result of echocardiographic navigation, because intraprocedural TEE frequently permitted continuation of the procedure in the situation of transient hemodynamic disorders (hypotension) associated with the traction of cardiac walls or superior vena cava (Figures 4 and 5). In this way, it was possible to avoid tamponade, and at the same time to maintain the high level of operator alertness. In accordance with the present results, previous studies have demonstrated a similar impact of echocardiographic monitoring on TLE effectiveness, confirming that continuous echocardiographic monitoring allows for the completion of the extraction procedure in these circumstances [16][17][18].
Furthermore, it should be underscored that TEE imaging provides a direct assessment of lead fragments that may remain after the extraction. It is of paramount importance for procedure effectiveness to visualize lead fragments or insulation remnants, which are invisible in fluoroscopy ( Figure 6). 1 Figure 6. Remnants in heart chambers after TLE. TEE images-mid-esophageal view, transaortic view-fragment of silicone insulation (yellow arrow) stripped off the lead during TLE, dislodged into the right ventricular outflow tract (RVOT) and the pulmonary trunk (TP) (A). TEE images of the extracted ventricular lead (black arrows): unchanged fragment, lead tip with elongated guide wire, a fragment of endocardial tissue (red arrow) and silicone insulation (yellow arrow), segment of the lead surrounded by a fibrous capsule (blue arrow) and endocardial tissue (the image confirming lead adhesion to cardiac tissues) (B). TEE images-mid-esophageal bicaval view-fragment of a thickened (hyperechogenic) atrial lead adhering to the atrial wall, fractured during TLE (white and blue arrows) (C). The free-floating tip was captured by a lasso catheter (red arrow) (D). This is especially important for the management of patients with infective endocarditis, in whom achievement of complete procedural success is associated with a better prognosis [13].
Similarly, it is important to visualize the migration of lead adhesions and vegetation, especially to the pulmonary artery. In these situations, TEE has an unquestionable advantage over fluoroscopy and is a valuable adjunct in the procedure of lead extraction (Figure 7) [10].
At short-term follow-up (6 and 12 months) survival after TLE was comparable between the groups. This is in accordance with earlier observations, which showed dissimilarity in risk factors for complications of TLE and factors influencing short-and long-term survival [5,11,12,22]. It is well known that survival after TLE is dependent mainly on clinical variables: patient age and comorbidities: diabetes mellitus, heart failure, renal failure. As previously stated, TEE-guided patients were characterized by older age and more comorbidities (Charlson comorbidity index 4.972 vs. 4.434; p < 0.001) compared with non-TEE-guided individuals, which must have contributed to the equalization of death rates between the two groups at follow-up.  Figure 7. TLE in the course of lead-related infective endocarditis with pulmonary embolization protection devices and TEE guidance. 2D and D TEE images-a vegetation 4.0 × 1.7 cm in size (red arrow) on the ventricular lead (blue arrow) in the right atrium (A). Fluoroscopy-a nitinol basket (yellow circle) positioned within the pulmonary artery (pulmonary embolization protection), pulling on both leads (lead-to-lead adhesion) during atrial lead extraction (B). TEE images-mid-esophageal view, dislodgement of the vegetation (red arrow) into the RVOT after removal of the ventricular lead (C). TEE images-upper esophageal view (Multi D imaging), vegetation fragment captured by the basket in the pulmonary artery (D). However, it should be emphasized that there were no periprocedural deaths among TEE-guided patients, whereas six patients died among the non-TEE-guided individuals. In view of the above, this is the first study to document that use of continuous TEE monitoring in patients undergoing transvenous lead extraction, and it translates directly into a reduction in periprocedural mortality.

Limitations
The organizational model of TLE procedures at the extraction centers was not the same and it did not take into account operator learning curves. Echocardiographic evaluation was not performed by one diagnostician. The study did not describe in detail the role of echocardiographic monitoring for the assessment of tricuspid valve function, as this parameter is not incorporated into the SAFeTY TLE scoring system.

Conclusions
This is the first study to confirm the higher procedural effectiveness and reduced incidence of cardiac tear and venous injury during transvenous lead extraction under transesophageal echocardiographic guidance. It was also shown that the use of continuous TEE monitoring was associated with a 100% periprocedural survival. Echocardiographic monitoring allows operators to perform many complex procedures safely and with more precision in patients at high procedural risk, through anticipating and thus preventing the occurrence of complications based on an analysis of changes in cardiac structures in response to the operator's maneuvers, which are invisible in fluoroscopy. Such behavior also contributes to the modification of procedures and techniques in some cases, and consequently minimizes the risk of major complications.