While fluoroscopy is a necessary tool for pacemaker (PM) and ICD implantation, and it is known that there is no safe level of radiation exposure, few articles exist that demonstrate the feasibility of a low-fluoroscopy approach to these procedures with minimal complications. This article aims to demonstrate that pacing device implants can be performed using minimal fluoroscopy without compromising safety.
Traditionally, fluoroscopy has been used for pacing device implants with little effort to limit patient exposure under the assumption that the risk of radiation exposure was minimal and the long-term negative impact was negligible. In addition, there has always been the concern about the potential for complications related to using too little imaging. Unfortunately, fluoroscopy requires the use of ionizing radiation, and it is well understood that there is no safe level of radiation exposure. In addition, as more patients undergo multiple radiation-based procedures (cardiac catheterizations, EP studies, CT scans, etc.), the cumulative dose of radiation can be significant.
While multiple papers have been published that demonstrate the efficacy and safety of using minimal or no fluoroscopy for electrophysiology studies and ablations, including pulmonary vein isolation (PVI), few have focused on device implant.
This is a retrospective review of techniques used for the implant of all new dual-chamber pacemaker and ICD implants by a single operator at a single center over 26 months. All 90 consecutive patients who presented for implant from August 1, 2015 to October 31, 2017 were included. Techniques to reduce fluoroscopy included the use of lowest available fluoroscopy frame rate, single-frame images saved for review, use of “fluoro-save” rather than “cine” runs, ultrasound-guided venous access, and no venography. Fluoroscopy time, radiation exposure, procedure time, and complications were analyzed.
A total of 90 devices were implanted: 29 dual-chamber pacemakers (DCPM) and 61 dual-chamber ICDs (ICD). Fluoroscopy time per procedure ranged from 0.1 to 4.5 minutes for DCPM (average 0.8; SD 0.4) and from 0.1 to 1.6 minutes for ICD (average 0.6; SD 0.8). Radiation exposure per procedure ranged from 0.5 to 62 air kerma for DCPM (average 6.1; SD 2.8) and from 0.7 to 15 air kerma for ICD (average 3.6; SD 10). Average time in the room was 95.2 and 91.0 minutes for DCPMs and ICDs, respectively. Air kerma was reported rather than the traditional mGy as it reflects a more accurate estimate of the dose absorbed by the patient.
There was one procedural complication: late pericardial effusion after DCPM implant requiring pericardiocentesis. The complication rate was 1.0%. There were two lead revisions (ICD only) and no pneumothoraces.
Techniques to Reduce Fluoroscopy Use
- Lowest available fluoroscopy frame rate. Our standard setting is 3.8 frames per second (f/s). I have found that reducing the frame exposure rate from 15 f/s to 7.5 f/s usually results in minimal change in image quality. Similarly, for most imaging requirements, reducing to 3.8 f/s provides adequate images.
- Single-frame images saved for review. One tap on the fluoroscopy pedal for imaging, coupled with the use of the “fluoro-save” feature to capture images rather than “cine” runs, limits not only exposure but also the need to take repeat pictures. Static images are displayed on the review screen side-by-side with the live image. By using the fluoro-save feature, even low-power moving images can be saved for review. Another advantage to this method is in reviewing the case. Should there be a question about what images the operator was using to make a decision about lead position, these can be reviewed from the stored file.
- Ultrasound-guided access. The use of handheld ultrasound to guide venous access nearly eliminates the risk of pneumothorax, fluoroscopy guidance of the needle tip, and venography. After the field is prepped and draped, the ultrasound probe is covered with a sterile wand cover and placed directly over the axillary vein. By angling the needle tip and maximizing contrast and depth, the needle can be visualized through the skin as it is advanced to the vein. By adding extra pressure, the vein can be caused to collapse, differentiating it from the artery. In addition, a single micropuncture access wire left in place after a single access puncture can be upsized to two standard peel-away sheaths, eliminating the need for an additional puncture. Should patient anatomy not allow for saved visualization of the target vessel, the wand can be placed in an open pocket, which reduces tissue interference and brings the vessel image closer.
- Purse-string suture around the access wire. Placement of a purse-string suture immediately after vein access and pocket formation allows the operator to achieve hemostasis at the vein access site in the pocket. After vascular access is achieved and the pocket is formed, a 0-silk stitch is placed in a box configuration around the access wire and left with a loose knot, which can be tightened after sheath removal. Next, this wire can be stepwise upsized to standard J wires and delivery sheaths.
- Passing leads into the heart. Once access sheaths are in place, the leads can be gently and safely advanced around the bend of the SVC into the right atrium without fluoroscopy. If resistance is noted, single-shot images can be obtained to confirm lead location. Usually, retracting the stylet a few centimeters will soften the lead tip enough to pass the lead safety past any resistance.
- Delivered dose is more important than fluoroscopy time. The amount of fluoroscopy time is only a general measure of exposure. Dose area product (DAP) is a measure of radiation delivered and more closely reflects radiation risk. It is often reported as Gy-cm2. However, the most accurate measure of radiation exposure to the patient may be air kerma (J/kg), which calculates the absorbed dose to the patient.
- Shielding. Using proper shielding (including radiation shielding pads to cover obese patients and limit body scatter) offers another layer of protection to the operator. We use a movable, boom-mounted shield. In addition, consider increasing operator body coverage lead to include a leaded face shield, lead cap, and arm and leg coverage in addition to a wraparound skirt.
- Collimation. Appropriate alignment of lenses through collimation reduces image area and decreases the delivered dose of radiation.
- Avoid magnification. Magnification increases the radiation dose. Using passive fix leads can reduce or eliminate the need for magnification to monitor extension and retraction of the lead’s helix tip.
- Projection angle. Avoid LAO, which compared with shallow RAO, reportedly results in a twofold increase in x-ray dose received by the patient. This is due to the need for x-ray to pass through the liver, vertebral column, and mediastinum, vs RAO, where the x-ray mainly passes through the lung.
- Positioning table/camera. Keep the patient’s table appropriately elevated and position the detector nearer to the patient while lowering the image intensifier. This can reduce scatter and radiation dose.
- Operator motivation. The single most effective means to reduce fluoroscopy use is operator motivation. Keeping a running tally of fluoroscopy times and dosages is a key tool for tracking progress.
Using the techniques identified here, average fluoroscopy time and radiation exposure during PM and ICD implant during this study were very low. Complication and lead revision rates were also low. The techniques identified in this article are easily implemented, and have led to a >90% reduction is fluoroscopy use during standard PM and ICD implants.
Disclosure: The author has no conflicts of interest to report regarding the content herein.