Splenic impedance indices: A useful method to monitor patients after liver transplantation?

Abstract

Splenic Doppler impedance indices are influenced, in portal hypertensive patients, by the resistance of the portal system. The aim of the study was to verify the usefulness of these indices in evaluating the presence of a pathological increase in portal resistance in patients with complications after liver transplantation. Splenic impedance indices have been evaluated in 46 patients before orthotopic liver transplantation (OLT), and 2 days, 1, 4, 8, and 12 to 18 months after transplantation. The results showed that spleen size slowly decreased after liver transplantation. From a baseline longitudinal diameter value of 18.0 ؎ 3.6 cm (M ؎ SD), the decrease was by 0% ؎ 3%, 8% ؎ 8%, 13% ؎ 9%, 15% ؎ 11%, and 14% ؎ 11% at 2 days and 1, 4, 8, and 12 to 18 months after liver transplantation. Splenic impedance indices-resistance index ‫؍‬ (peak systolic ؊ end diastolic) / peak systolic velocity; pulsatility index ‫؍‬ (peak systolic ؊ end diastolic) / mean velocity-which were increased before liver transplantation, showed a rapid decrease to normal values: resistance index: from 0. The measurement of Doppler impedance indices (DIIs) is a simple and noninvasive method to evaluate alterations in arterial and venous hemodynamics associated with different pathological conditions. 1,2 These indices are mainly considered as parameters of arterial resistance, 2-4 but their interpretation varies according to the investigated organ. In particular, intra-splenic DIIs are influenced by venous congestion of the organ, as they are related to spleno-portal vascular resistance. 5 To confirm this, we have recently shown that splenic DIIs are higher on average in patients with cirrhosis and portal hypertension than in normal subjects, and they normalize after orthotopic liver transplantation (OLT). 5 The aim of the study was the evaluation of DIIs during the follow-up of patients with OLT, and of the relationships between these indices and the outcome of these patients thus establishing the clinical usefulness of the method. PATIENTS AND METHODSPatients. Forty-six patients (35 males and 11 females) with cirrhosis, who consecutively underwent OLT, were investigated. When OLT was performed, age of patients averaged 47 Ϯ 9 years (M Ϯ SD) (range 22-63). The cause of cirrhosis was alcoholic in 10 patients, posthepatitic in 23 (hepatitis B virus[HBV]-related in 7 patients, hepatitis C virus [HCV]-related in 15 patients, HBV-, HBC-, and hepatitis D virus [HDV]-related in 1 patient), mixed in 8 (HBV-related and alcoholic in 2 patients, HCV-related and alcoholic in 4 patients, HBV-and HCV-related, and alcoholic in 1 patient, HBV-and HDV-related and alcoholic in 1 patient), primary biliary in 3, secondary biliary in 2. According to Child-Pugh classification, 6 when they underwent OLT, 1 patient was class A, 31 patients were class B, and 14 were class C.All patients underwent a splanchnic duplex Doppler ultrasonography every 2 months, while they were on the waiting list for OLT. Therefore, baseline measurements were performed approxiamtely 1 month b...

Systemic and splanchnic hemodynamic changes after liver transplantation for cirrhosis: A long-term prospective study

“…16 One possible factor contributing to this abnormality could be the patency of portosystemic collateral vessels, which have been demonstrated to persist long after transplantation 35 and provide a low-resistance downstream pathway for mesenteric flow. The persistent spleen enlargement after OLT, also described by previous studies, 13,35 might also contribute to the maintenance of the collateral circulation patent and vice versa. However, such portosystemic connection alone cannot fully justify a splanchnic hyperkinetic circulation in the absence of an increased cardiac output, as it was in our case.…”

“…Other hemodynamic consequences are observed in the splanchnic arterial system, in particular in the splenic, hepatic, and superior mesenteric arteries. [12][13][14][15][16][17] In the two former arterial districts, Doppler impedance indices correlate with portal resistance, 12,17 while in the latter, their reduction likely reflects the splanchnic hyperkinetic circulation. To our knowledge, very few studies have been focused on the splanchnic hemodynamic changes occurring in liver transplant recipients.…”

Influence of Liver Fibrosis on Hepatic Artery Doppler Resistance Index in Chronic Hepatitis of Viral Origin

“…The decrease of pulsatility index in the superior mesenteric artery in established cirrhosis therefore indicates the presence of vasodilation (15), which is hypothesized to be caused by circulating vasoactive agents (16)(17)(18). Impedance indexes in the splenic artery have been reported to be strictly related to transhepatic portal resistance (19) and to re ect its changes in pathological conditions or after surgery (10,11). Contrary to this, the mechanisms underlying the alteration of hepatic artery Doppler impedance indexes are still a matter of debate, but are generally attributed to the hepatic architectural distortion (7)(8)(9)20).…”

“…On average, portal velocity is not reduced in chronic hepatitis, but it has been reported to be statistically slower in chronic hepatitis with pronounced brosis than in chronic hepatitis with little brosis (6). In recent years, the exploration of splanchnic arteries has provided new information on portal hypertension and has demonstrated that Doppler impedance indexes are increased in both the hepatic artery (7)(8)(9) and the splenic artery (10,11) and decreased in the superior mesenteric artery (12). Doppler impedance indexes derive from the Doppler spectrum and allow an indirect estimate of the downstream vascular resistance in compliant systems with a pulsatile ow, such as blood vessels (13,14).…”

Doppler ultrasonography combined with transient elastography improves the non-invasive assessment of fibrosis in patients with chronic liver diseases

“…It can define the velocity and characteristics of blood flow within the portal system and the hepatic and splenic arteries [2,13]. Previous studies have shown that portal vein flow velocity [14,[15][16][17][18] and resistance index of the hepatic [1,14,[20][21][22] and splenic artery [21,[23][24][25][26] mirror the severity of portal hypertension in patients with cirrhosis. Given these observations, DUS is routinely used in the follow-up of patients with cirrhosis.…”