Elastography of the Spleen as an Acute Measure of Portal Hypertension in Patients with Transjugular Intrahepatic Portosystemic Shunt (TIPS): A Systematic Review of the Literature and Future Directions

Abstract

Background: Although Transjugular Intrahepatic Portosystemic Shunts (TIPS) are effective procedures to alleviate portal hypertension [1], these artificial shunts are inherently prone to stenosis over time and therefore require monitoring [2]. Because direct portal pressure measurement is invasive and impractical for clinical follow-up, noninvasive monitoring measures have been attempted. Due to its anatomic relationship with the portal vein, spleen stiffness (SS), quantified via elastography, has been proposed as a noninvasive measure of TIPS function. Therefore, the objectives of this study were to: (a) review literature on SS as an acute measure of portal hypertension and shunt function in patients with TIPS, and (b) characterize the cohort of patients undergoing TIPS insertion at the University of Kansas Medical Center (KUMC) in anticipation of a prospective study at this institution. Methods: Through a systematic search of PubMed, five studies measuring SS before and after TIPS placement were identified and compared [3-7]. Data extracted from each study included: geographic location, number of subjects, subject characteristics, timing of elastography measurements, elastography exam technique, and findings. Additionally, the HERON (Healthcare Enterprise Repository for Ontological Narration) institutional database was used to generate a potential cohort of study subjects that included all adults who underwent TIPS insertion at KUMC from January 1, 2010 through September 27, 2016. CPT, ICD-9 and ICD-10 diagnosis codes, vital status, and death date were selected using the HERON query tool. TIPS outcomes, including TIPS revision, liver transplantation, and mortality, were measured at six months, one year, two years, and beyond two years. Results: Four of the five studies found that splenic stiffness decreased after TIPS placement [3, 4, 6, 7], while the fifth documented mixed results [5]. Timing of measurements, imaging modalities, and embolization of collateral veins during TIPS placement differed among studies. The HERON search resulted in 298 patients for our cohort analysis – 59.1% were male, 85.2% were white, with an average of 56.3 years (SD±12.5). Within the follow-up period (range zero months to over five years), 30% (n=90) of patients underwent at least one TIPS revision, 16% (n=47) underwent liver transplantation, and 15% (n=46) died after TIPS placement. Conclusions: Reports of the utility of splenic elastography as an acute measure of portal hypertension in TIPS patients are promising, although somewhat conflicting. Discrepancies in study findings may be attributed to differences in patient characteristics, elastography technique and timing, or embolization of collateral veins. A larger, prospective study is warranted, as elastography has the potential to be a safe, noninvasive, cost-effective measure of TIPS function. Because KUMC performs a substantial number of TIPS procedures in a diverse patient population, it is an ideal site for such a future study.