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

Abstract

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.

Keywords: Catheterization; Drug delivery vehicle; Endovascular procedure; HPE; Hydrophilic polymer embolism; Iatrogenic complication; Vasculopathy.

Figure 1. Summary, Patient 1

A 73-year-old woman with hypertrophic cardiomyopathy, sinus node dysfunction, hypertension, diabetes mellitus type 2 and chronic renal disease presented with pulmonary edema. Cardiac enzymes were negative; BNP and creatinine were elevated. Initially, the patient was improving with diuresis, intravenous fluids and dialysis. After admission, a CVC was placed and broad-spectrum antibiotics were administered for suspected pneumonia. The patient's respiratory symptoms subsequently worsened; however, transthoracic echocardiography and right and left cardiac catheterization revealed no definite cardiac etiology for her symptoms. During her hospitalization, she developed suspected PE, elevated ESR, p-ANCA+ vasculitis, coagulopathy of unknown cause, and prominent mediastinal lymphadenopathy. Chest X-Ray (A) and pulmonary CT angiography (B) showed pleural effusions and areas of pulmonary consolidation, with no evidence of PE. Despite multiple negative cultures, the patient developed multiple organ dysfunction syndrome and suspected sepsis, progressing to death. Autopsy, performed 1 month after admission, failed to reveal any natural etiology for her terminal symptoms. Retrospective histopathological analysis, however, showed multifocal HPE involving the bilateral peripheral pulmonary arteries (C-F), as well as the heart and central nervous system (not shown). Intravascular histiocytes (D), giant cells (E), and fibrous reaction (F) were associated with HPE. Adjacent vessels showed microthrombus formation (G) and areas of vascular injury (H). The cause of death was retrospectively attributed to widespread pulmonary HPE in the setting of hypertrophic cardiomyopathy [C-H: H&E, original matnification 600X].

Figure 2. Summary, HPE Vasculopathy

Heterogeneous reactions (A) elicited by intravascular polymer include foreign body giant cell vasculitis (arrow 1), intravascular microabscess formation (arrow 2); intravascular fibrous reaction (arrow 3); and histiocytic response (arrow 4) (magnified in panels B-E, respectively); high-power microscopy further demonstrates lamellated strips of foreign granular material, consistent with polymer [A-F: H&E; G: Congo Red; H: Mucicarmine; H: Masson Trichrome; A: 200X; B-I: 400X].