Iatrogenic Deep Musculocutaneous Radiation Injury Following Percutaneous Coronary Intervention

JoAn L. Monaco, MD, Kanika Bowen, AB, Peter N. Tadros, MD, Peter D. Witt, MD
JoAn L. Monaco, MD, Kanika Bowen, AB, Peter N. Tadros, MD, Peter D. Witt, MD
Coronary angiography and intervention are important tools that have greatly improved long-term survival for patients with ischemic heart disease. Extensive radiation received during prolonged fluoroscopic procedures has created a resurgence of cases of radiodermatitis, a clinical problem that had been declining after improvements in the technology of external beam radiation, and is now seldom seen among inpatient dermatology consultations. The dorsal and lateral thoracic locations of these radiation defects may be difficult soft tissue management problems. Factors that determine the extent of injury include radiation dose, mode of fluoroscopy, site of radiation and whether or not the dose was fractionated. Previous studies indicate that as little as 1 episode of percutaneous coronary intervention (PCI) may lead to cutaneous injury, with the duration of fluoroscopic exposure directly correlated to the extent of epithelial damage. However, the occurrence of deep muscle damage as a result of single PCI treatment has not yet been described. We document 1 such case involving a 59-year-old man with a large radiation-induced wound to the back after prolonged fluoroscopic exposure during PCI. Case Report. A 59-year-old obese man with unstable angina pectoris, diabetes mellitus and hyperlipidemia underwent PCI at an outlying facility. The age of the fluoroscopic equipment is unknown. The 5-hour procedure attempted to treat a 95% distal stenosis in a severely calcified right coronary artery. 3.0 Maverick and 3.0 Quantum Ranger angioplasty dilatation catheters were inflated to a maximum of 20 atmospheres (atm). Despite 15 balloon dilatations that occurred during the course of the procedure, there was a 70% residual narrowing post-dilatation. The procedure was done using Siemens biplane radiology equipment, with table rotation for cranial and caudal views. Magnification was 17 cm at 50 frames per second in biplane mode for 91% of the total film acquisition time for the PCI procedure. Radiation times were measured independently for each plane using standard dosimeters (AAR national parameter, 802). The total fluoroscopic time for the case was 55 minutes. Erythematous skin changes on the back were evident on the second day following the patient’s interventional procedure. Subsequently, the injury evolved into an exquisitely tender 30 x 30 cm radiation-induced wound over the next 3 weeks. Despite local wound therapy, the clinical picture deteriorated with development of a green/yellow bloody mucopurulent exudate adherent to the sclerotic surface containing telangiectasias (Figure 1). The patient was then referred to the plastic surgery service for wound management. Preoperative incisional biopsy showed perivascular infiltrate, dermal edema and inflammation, and swelling of epithelial cells. The fibrinoid changes were consistent with radiation injury (epidermal atrophy, abundant stellate fibroblasts, lymphocytes and plasma cells). The patient was admitted to the hospital 5 months after his PCI treatment because of recurrent bouts of cellulitis, overt secondary pseudomonas infection and nonhealing ulcerations on his back. The extent of peripheral wound injury and a wound depth to the level of the spinous muscle fascia precluded either primary closure or skin grafting. Operative management consisted of wide local debridement (Figures 2 and 3) and reverse latissimus dorsi muscle flap based on medial perforators following detachment of the anterior tendinous edge of the muscle. The section of the latissimus dorsi muscle approximately 15 cm from the lumbar vertebrae yielded an ideal match to fit the excised area (Figure 4). A meshed 30 x 30 cm split-thickness skin graft was harvested at 0.11´´ thickness from his lower back to cover the latissimus dorsi muscle flap. Stable wound coverage was noted 8 weeks postoperatively (Figure 5). Discussion. PCI has become one of the leading procedures to effectively treat coronary artery disease. Relatively high amounts of radiation exposure have been considered a necessary consequence of complex coronary interventional procedures. With increasing procedure complexity and frequent repeat procedures performed, there has been growing concern regarding the magnitude of cumulative exposure to patients. Several reports in the recent literature indicate that radiation dermatitis is a serious and often unrecognized complication of interventional radiation procedures. Such iatrogeny is secondary to prolonged radiation exposure during PCI or multiple catheterization procedures. This case report is intended to heighten awareness that deep muscle injury may result from a single, isolated treatment. In comparison with angiography, PCI exposes the patient to 3.4 times more radiation.1 Fluoroscopy contributes 74% radiation exposure during PCI compared to 35% for diagnostic coronary arteriography.2 Admittedly, the reason that a lower percentage of fluoroscopy time is utilized in diagnostic catheterization compared to PCI is that most of the time during diagnostic catheterization is spent in image acquisition. The issue of clinical importance is the total fluoroscopic time. Diagnostic angiography fluoroscopy time lasts 2–3 minutes, whereas routine PCI fluoroscopy time lasts 10–15 minutes with the most complex cases extending from 25–40 minutes. We do not advocate that current safety guidelines be modified, because of the rarity of the phenomenon under discussion. However, physicians should integrate the risks of radiation-induced complications in their decision-making to determine the risk-benefit ratio of complex interventional procedures. Additionally, the concern for cumulative radiation exposure should also be considered in patients who have previously undergone multiple fluoroscopically-based interventional procedures. For example, once a certain threshold for radiation exposure is reached, consideration should be given to an alternative treatment plan such as coronary artery bypass grafting or acceptance of myocardial infarction. The United States Food and Drug Administration (FDA) is informing physicians about the higher risks of fluoroscopically guided procedures.3,4 Risk assessment and future management guidelines await consensual validation by large numbers of patients and prospective studies. In the meantime, some risk factors have been loosely defined for skin injury: advanced age, prior malignancy and previous radiation exposure. Skin injury is most contingent on the length of the procedure and the radiation dosage. Typical threshold doses for various effects are: 2 Gy for early transient erythema; 3 Gy for temporary epilation; 6 Gy for persistent erythema; 7 Gy for permanent epilation; 10 Gy for dry desquamation; and 15–20 Gy for moist desquamation, dermal necrosis and secondary ulceration.5 A study performed utilizing fluoroscopic equipment from the early 1990s demonstrated the average dose for PCI to be 6.4 Gy.1 Thus, even a single PCI procedure may produce epithelial damage. When skin cells are damaged due to high levels of radiation, the skin loses its ability to effectively regenerate, which can lead to ulceration, hypergranulosis and necrosis. Generally, effective wound closure of these difficult cases requires a skin graft. Hyperbaric oxygen therapy may be useful in these situations, because it acts as an inhibitor of reperfusion injury and as a signal to increase trophic factors. The development of both cutaneous and deep muscular damage as described in this case report emphasizes the need for comprehensive evaluation of complications related to prolonged radiation exposure during fluoroscopically-based interventional procedures. Increased cumulative radiation also leads to an increased risk of squamous and basal cell carcinoma.6 In a recent report comparing PCI to coronary artery bypass grafting, PCI patients had 10 times more related deaths at 5 years than the surgical group.7 In addition to restenosis, the unrelenting and progressive nature of coronary artery disease requires many patients to receive multiple PCI exposures during their lifetime. This risk, especially for malignancy, is not well defined. We recognize that the radiation risk from a single PCI case is likely very low, and that the experience we report is a rare exception. Furthermore, the amount of fluoroscopic radiation exposure during coronary procedures has dramatically decreased over the past 5 years for several reasons. First, fluoroscopic cardiac equipment has undergone immense improvement, with many cardiac catheterization laboratories upgrading from older equipment that previously generated high radiation doses. Second, physician education mandated by the American Board of Internal Medicine and the American College of Cardiologists for both existing cardiologists and cardiology fellows has made operators keenly aware of radiation exposure to patients. This awareness was prompted by the United States FDA public health advisory of 1994.3,4 Most importantly, the equipment utilized to perform PCI has dramatically improved, thereby allowing the interventional cardiologist to perform the procedures expeditiously. These technical improvements have significantly reduced fluoroscopy times. Currently, the majority of PCI cases do not exceed 25 minutes of fluoroscopy time. However, there will always be complex cases that require substantially longer exposure times to complete. We suspect that the cardiologist in this case spent most of the fluoroscopy time attempting to deliver a stent to the very calcified right coronary artery. The suboptimal balloon result (70%) is presumptive evidence for this statement. Ordinarily, a 70% residual stenosis would be considered a failure of PCI and possibly place the patient at risk for an acute inferior wall myocardial infarction. If this perception is true, total fluoroscopy time, as demonstrated previously, is really the central issue of this case report. The stochastic risk per PCI procedure and repeated use are concerns as national health issues and warrant further investigation. Recommendations to reduce radiation-induced damage include careful examination of the skin site before each procedure, minimized fluoroscopy time, utilization of pulse fluoroscopy, employment of radiation filters, and collimator’s and rotation of the location of the image intensifier.
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