Original contributionHydrophilic polymer embolism and associated vasculopathy of the lung: prevalence in a retrospective autopsy study☆
Introduction
Hydrophilic polymers are increasingly used for biomedical applications. Enhanced lubrication and biocompatibility, made possible by hydrophilic coats on cardiovascular and neurointerventional devices, allow for less invasive approaches for common endovascular procedures [1], [2], [3]. The advent of drug-eluting polymers additionally allows for sustained, targeted release of intravascular drugs, which improve therapeutic efficacy and compliance while reducing systemic drug toxicities. With advanced nanotechnologies and evolution of bioengineered insertable and implantable “smart devices,” manufacturers will continue to incorporate this material on new and emerging vascular devices [4], [5], [6].
Despite their technological advances, polymer coating materials have been shown to dissociate from device surfaces during endovascular manipulation [7], [8], [9], [10], [11], [12], [13], [14], [15], [16] or after implantation of devices in patients [9]. These foreign materials may then deposit in unexpected locations within the body. Recent studies conducted by our group document morbidity and mortality attributable to embolization of polymer particles within the bloodstream [12], [13]. Thus, hydrophilic polymer embolism (HPE), a term we introduced in 2010, has recently been established as a potentially fatal iatrogenic phenomenon [13], although its frequency in populations at risk has not been clear.
Although vascular devices undergo friction, durability, and particulate trials required by the US Food and Drug Administration (USP XXII, sec 788) [17], complications associated with intravascular polymer applications are not fully recognized by the medical community [12], [13], [18], [19]. To date, the clinicopathological effects associated with HPE have not been systematically evaluated. The recent observation of widespread polymer microemboli in a new fatal case prompted us to perform a retrospective analysis at a tertiary care hospital. Herein, we report the detectable frequency of this condition and analyze associated pulmonary vascular changes in affected patients who died in a hospital setting and underwent autopsy.
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Autopsy material and tissue processing
During a 29-month interval, from January 1, 2010 to May 30, 2012, 2766 patients died at the University of Maryland, Baltimore, Medical System. Of the total deaths, 198 in-hospital autopsy requests were made during this period. Of these, 54 fetal, stillborn, or infant pediatric autopsies were excluded from this study; slides were unavailable in our files on 6 cases; 2 cases consisted of gross examination only. Corresponding tissue slides for the remaining 136 cases were included in this study.
Patient autopsies
A total of 4794 tissue slides originating from 136 adult and adolescent hospital autopsies were evaluated (patient age range, 10-96 years; 53% male). Per autopsy consent, 85 cases were unrestricted autopsies; 26 cases excluded examination of the head; 19 cases consisted only of chest examination; 4 autopsies were limited to examination of the heart, abdomen, pancreas, or liver only; whereas, 2 cases were limited to examination of the brain.
Of 136 autopsy cases examined, 18 cases (13%) showed
Discussion
Hydrophilic coating materials are widely used on medical devices and have revolutionized catheterization and endovascular devices and techniques. Despite their numerous unique advantages, these substances occasionally dissociate from device surfaces and deposit within the bloodstream, thereby embolizing distally during clinical use [13]. Intracerebral polymer microemboli were first described by Barnwell et al [7] after use of infusion microcatheters (Target Therapeutics, Fremont, CA).
Acknowledgments
The authors are grateful to Dr. Allen P. Burke for his assistance with data analysis and would like to acknowledge Mrs. Stephanie Dampier and Mrs. Rekha Prasad for their technical assistance.
Funding/Support: R.I.M. is supported by a grant from the National Institute of Neurological Disorders and Stroke (K08-NS089830).
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Competing interests: None.