A 47-year-old male patient with a history of atrial fibrillation and hypertrophic obstructive cardiomyopathy status-post alcohol septal ablation dual-chamber automatic implantable cardioverter defibrillator (AICD) implantation presented for surgical AICD lead extraction for presumed infection. The patient developed bacteremia weeks after implantation of the AICD and was evaluated by transthoracic echocardiographic examination (TTE), which failed to show clear evidence of lead-related infective endocarditis. Despite a prolonged course of antibiotics, a systemic infection continued as evidenced by the bacteremia; therefore, the patient was scheduled for AICD removal.
An intraoperative transesophageal echocardiographic (TEE) examination was performed during extraction of the leads to assess for valvular endocarditis as well as a pericardial effusion postlead extraction. On examination, a right-sided, lead-related vegetation was demonstrated by TEE, which had not been visualized by TTE. From the midesophageal (ME) 4-chamber, ME right ventricular (RV) inflow-outflow, and ME bicaval views, the vegetation appeared to surround the RV lead from RV apex to the superior vena cava (SVC)-right atrial (RA) junction (Supplemental Digital Content 1, Video 1, http://links.lww.com/AA/B64). Additionally, the transgastric RV inflow view showed an echodense, thickened fibrin sheath adhering to the RV lead (Fig. 1; Supplemental Digital Content 1, Video 1, http://links.lww.com/AA/B64). No masses were seen attached to the RA lead.
After the leads were removed without complication, a repeat TEE revealed a free-floating mobile mass (approximately 3.1 × 1.3 cm) with complex morphology extending from the SVC into the RA. This mass was best visualized from the ME RV inflow-outflow and ME bicaval views (Fig. 2; Supplemental Digital Content 2, Video 2, http://links.lww.com/AA/B65). No flow disturbances were detected with color flow mapping secondary to the mass, and the risk of paradoxical embolism was deemed to be absent because a patent foramen ovale was not visualized. The mass was not removed, and the patient recovered uneventfully from the lead removal without signs of hemodynamic compromise from either a pericardial effusion or embolization of the mass.
TEE is believed to be more sensitive than TTE for the detection of lead-related infective endocarditis, and because of the high potential for a nondiagnostic study, both the American Heart Association and the American Society of Echocardiography recommend TEE to assess lead-related infective endocarditis.1,2 The poor sensitivity of TTE is explained at least partially by the location of vegetations in patients with lead-related infective endocarditis. These patients commonly develop vegetations at the level of the SVC and upper portion of the RA, which is visualized better with the use of TEE.2 Additionally, TEE allows for better characterization of the morphologic features of lead vegetations, such as size, shape, mobility, and precise attachment points.3 Finally, patients with signs of systemic infection can develop left-sided endocarditis, for which TEE is superior in diagnosing.
When evaluating the right heart for signs of lead-related infective endocarditis, a complete examination should be performed, including the ME 4-chamber, ME RV inflow-outflow, ME-modified bicaval tricuspid valve, ME bicaval, and transgastric RV inflow views, as defined by the American Society of Echocardiography. The RA lead can be identified by visualizing the implantation site in either the RA appendage or lateral RA wall, which can be visualized in the ME bicaval view immediately adjacent to the SVC. Additionally, a left ventricular lead can be visualized as it enters the coronary sinus by advancing the probe from a ME 4-chamber to a deep esophageal position. A complete examination should include evaluation of normal cardiac structures (i.e., tricuspid, Eustachian, and pulmonary valve) because they are also potential locations for right-sided vegetations. Care should be taken to avoid mistaking the cristae terminalis (a smooth muscular ridge in the superior aspect of the RA and RV trabeculations) for a mass. Finally, the presence of a patent foramen ovale should be evaluated to determine the risk of a paradoxical embolism.
Determination of the lead type (i.e., defibrillator versus pacing lead) is not possible with TEE alone; however, lead insertion locations (i.e., RA, RV, coronary sinus) can aid in determining which lead is being evaluated. The hyperechogenic leads are strong reflectors of ultrasound waves and thus create reverberation and shadowing artifacts. These artifacts can make determining the attachment point (i.e., intracardiac structure versus lead) of a mass challenging. Fibrin sheaths often circumscribe leads and are less echogenic than the leads they envelop. Thus, the presence of a fibrin sheath can be determined by visualizing the brighter (i.e., greater echogenicity) lead enveloped by the less bright fibrin sheath (Fig. 1).
After lead extraction, a residual mass (i.e., fibrin sheath of the lead) often remains intracardiac. Le Dolley et al.4 coined the term ghost to describe the residual floating fibrin sheath of the lead. Although differentiating whether a ghost is a vegetation or a mobile thrombus with TEE is not possible, these authors demonstrated a strong association between the presence of ghosts and lead-related infective endocarditis (odds ratio, 7.6). The implications of a ghost after extraction remain unknown.
Previous reports have recommended surgical removal of a right-sided mass if it is >2 cm in diameter because of the concern of embolization.5 In patients without infection, Supple et al.6 demonstrated an increase in echocardiographic-estimated pulmonary artery systolic pressure of 39 vs 33 mm Hg in patients with mobile thrombi on AICD leads versus patients without thrombi present but showed no difference in qualitative RV function. Of the 17 patients with ghosts followed by Le Dolley et al., 2 patients died suddenly within 3 months of lead extraction despite having an uncomplicated lead extraction and lacking significant comorbidities.4 Additionally, a third patient presented with a symptomatic pulmonary embolism days after extraction. Conversely, Sohail et al.7 reported no complications relating to embolization of a vegetation after lead extraction in 147 patients despite some vegetations being up to 7.0 cm in the longest dimension.
The lack of complications reported by Sohail et al. may have been related to the complex morphology of an infected vegetation. Despite being long in 1 dimension, vegetations are potentially much smaller in other dimensions, thus making evaluation of the true size of a vegetation with 2-dimension echocardiography problematic. Three-dimensional or simultaneous 2-dimensional echocardiography (i.e., ×plane) could theoretically improve evaluation of the morphology of a vegetation and attachment points as well as better characterize the risks of embolization. Unfortunately, there are no current studies pertaining to the benefit of these echocardiographic modalities in right-sided endocarditis.
A complete examination of the right heart should be performed with TEE when evaluating for lead-related infections. This should include a description of the morphologic features of a vegetation, including its size, location, and attachment point.
Furthermore, a TEE at the time of lead extraction has the benefit of diagnosing the presence of a fibrin sheath and residual mass. Further research is needed to determine the importance of this finding and aid choosing the appropriate management of these patients.
Clinician’s Key Teaching Points
By Roman M. Sniecinski, MD, Nikolaos J. Skubas, MD, and Martin J. London, MD
- Transesophageal echocardiography (TEE) is better suited for detecting masses on pacemakers and implantable defibrillators than transthoracic echocardiography. In addition to the greater resolution of TEE, it also better visualizes the leads at the level of the superior vena cava and upper portion of the right atrium.
- Vegetations on infected leads typically have a much softer echogenicity than the leads they envelop because of their fibrin sheath. The leads themselves are highly echogenic and will appear much brighter.
- In this case, intraoperative TEE was able to detect lead-related vegetations that transthoracic echocardiography was not. Additionally, TEE showed the fibrin sheath remnants, often termed ghosts, that remained in the heart after lead extraction, and the significance of which is uncertain.
- A thorough intraoperative TEE examination is recommended in cases of endocarditis to ensure that there are not additional masses on valves or other structures. Potential pitfalls include mistaking the cristae terminalis in the right atrium and trabeculations of the right ventricle for abnormal masses.
Name: R. Kyle Branham, MD.
Contribution: This author helped write the manuscript.
Attestation: R. Kyle Branham approved the final manuscript.
Name: Alan C. Finley, MD.
Contribution: This author helped write the manuscript.
Attestation: Alan C. Finley approved the final manuscript.
Name: James H. Abernathy III, MD, MPH.
Contribution: This author helped write the manuscript.
Attestation: James H. Abernathy III approved the final manuscript.
This manuscript was handled by: Martin J. London, MD.
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