Elsevier

Human Pathology

Volume 46, Issue 2, February 2015, Pages 191-201
Human Pathology

Original contribution
Hydrophilic polymer embolism and associated vasculopathy of the lung: prevalence in a retrospective autopsy study

https://doi.org/10.1016/j.humpath.2014.09.011Get rights and content

Summary

Hydrophilic polymers are commonly applied as surface coatings on vascular devices and have been shown to dissociate during endovascular use, causing hydrophilic polymer embolism (HPE). Adverse effects related to this phenomenon have been recognized and reported. The prevalence of this complication is unknown. We conducted a retrospective study to determine the prevalence of HPE among hospital autopsies over a 29-month period. Postmortem tissue was histologically evaluated for the presence, location(s) and extent of HPE. HPE findings were correlated with documented clinical and laboratory data and patient outcome. Of 136 hospital autopsies examined, 18 (13%) showed evidence of HPE involving the lungs (n = 18), heart (n = 1) or central nervous system (n = 1). Localized pulmonary HPE was seen in 12 patients (9%). Multifocal pulmonary HPE was found in 6 patients (4%) and was associated with clinical vasculitis (33%; P < .0001), suspected pulmonary ischemia (50%; P = .008), coagulopathy (67%; P = .002), and constitutional disease (83%; P = .01). Within affected lung, associated histopathologic changes included occlusive intravascular or perivascular inflammation (89%), intravascular fibrous response (56%), microthrombus formation (44%), vasculitis (28%), and/or pulmonary microinfarction (28%). Statistically significant differences in hospital days (P = .008) and number of vascular interventions (P = .01) were noted between affected and unaffected patients. We conclude that HPE is an underdiagnosed phenomenon with primary involvement of the lungs, where secondary vascular changes are common. Additional studies may be needed to clarify risks and to identify preventative strategies for this iatrogenic complication of catheterizations and “minimally invasive” endovascular techniques.

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.

Section snippets

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.

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