Lack of Reciprocal Interference Between Capsule Endoscope and Left Ventricular Assist Device

Capsule endoscopy is being used increasingly in the diagnosis of obscure gastrointestinal bleeding, with a better diagnostic yield than the more invasive push enteroscopy [1], and is now accepted as a first-line diagnostic tool in hemodynamically stable patients in this setting [2]. However, because capsule endoscopy technology operates via 440-MHz radiofrequency signalling from the capsule to the belt-worn recorder, it is adversely affected by strong electromagnetic fields, and there are concerns regarding its use in patients with implanted electronic devices (e. g. cardiac pacemakers, implanted cardioverter defibrillators). In addition, the user’s manual for the M2A capsule (Given Imaging, Yoqneam, Israel) clearly states that capsule endoscopy is contraindicated in patients who have such types of devices fitted. Most of these patients are on chronic oral anticoagulant therapy, however, and gastrointestinal bleeding is not uncommon in the course of their disease.

The safety of capsule endoscopy in patients with cardiac pacemakers has been addressed in three studies. The first was by Leighton et al. [3] and involved five patients with cardiac subclavian pacemakers, who were monitored electrocardiographically during capsule endoscopy. No reciprocal interferences were noted in these patients. The second study, by Dubner et al. [4], involved 100 patients with cardiac pacemakers (mainly bipolar) who were challenged with a “test cap”, a radiofrequency-emitting device with the same wavelength as capsule endoscopy. This revealed minor pacemaker interference in only 4 % of patients, when the test cap was at a distance of less than 10 cm from the pacemaker. In the third study, Payeras et al. [5] analyzed combined in vitro and in vivo data on 20 patients with pacemakers and did not observe any significant interference between the capsules and the pacemakers. The short distance between the capsule endoscope and the pacemaker seems to be critical for interference and this is supported by the observation of prolonged gaps in the capsule endoscopy recording in one patient with a pacemaker implanted in the upper abdomen [6].

Although these studies are reassuring in terms of safety and lack of clinically significant interference between capsule endoscope and pacemaker, to our knowledge no data exist on the feasibility and safety of capsule endoscopy in patients with other electronically-driven, life-sustaining devices. Here we report the case of a patient with a left ventricular assist device (LVAD) who was submitted to capsule endoscopy for the investigation of obscure gastrointestinal bleeding.

Briefly, in December 2004, a 42-year-old man with a 6-year history of idiopathic dilated cardiomyopathy, which was refractory to intensive intravenous medical treatment, underwent successful implantation of an LVAD as a bridge to cardiac transplantation. An intensive regime of anticoagulation therapy, with warfarin, aspirin, and low molecular weight heparin was started. The device used was a Berlin Heart INCOR (Berlin Heart AG, Berlin, Germany) [7], which consists of an axial flow pump implanted in the anterior mediastinum just above the diaphragm, electrically powered by an external control unit connected to a percutaneous cable. The pump impeller is suspended by magnetic bearings and rotates at a speed of 5000 - 10 000 revolutions per minute. Both pump and cable are electromagnetically shielded. Three months later, the patient developed chronic melena and he required treatment with two to three units of blood weekly. Repeated upper and lower endoscopy, splanchnic arteriography, and tagged red blood cells scintiscan were all unrevealing. Although there were concerns regarding possible interference with the functioning of the LVAD, capsule endoscopy was performed. All LVAD parameters were monitored and no hemodynamic, electronic, or mechanical abnormalities or malfunction were observed. Moreover, capsule endoscopy data entry and image quality were excellent, though the procedure unfortunately did not disclose any source of gastrointestinal bleeding. The capsule was excreted naturally 24 hours later without any adverse event.

In conclusion, no interference was found between the capsule endoscope and the Berlin Heart INCOR LVAD in our patient, but more studies are needed to address the issue of the safety of capsule endoscopy in patients with a total artificial heart.

References

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