New insights into the regulation of hepatic blood flow after ischemia and reperfusion

The role of oxygen intake and liver enzyme on the dynamics of damaged hepatocytes: Implications to ischaemic liver injury via a mathematical model

Ischaemic Hepatitis (IH) or Hypoxic Hepatitis (HH) also known as centrilobular liver cell necrosis is an acute liver injury characterized by a rapid increase in serum aminotransferase. The liver injury typically results from different underlying medical conditions such as cardiac failure, respiratory failure and septic shock in which the liver becomes damaged due to deprivation of either blood or oxygen. IH is a potentially lethal condition that is often preventable if diagnosed timely. The role of mechanisms that cause IH is often not well understood, making it difficult to diagnose or accurately quantify the patterns of related biomarkers. In most patients, currently, the only way to determine a case of IH is to rule out all other possible conditions for liver injuries. A better understanding of the liver's response to IH is necessary to aid in its diagnosis, measurement, and improve outcomes. The goal of this study is to identify mechanisms that can alter associated biomarkers for reducing the density of damaged hepatocytes, and thus reduce the chances of IH. We develop a mathematical model capturing dynamics of hepatocytes in the liver through the rise and fall of associated liver enzymes aspartate transaminase (AST), alanine transaminase (ALT) and lactate dehydrogenase (LDH) related to the condition of IH. The model analysis provides a novel approach to predict the level of biomarkers given variations in the systemic oxygen in the body. Using IH patient data in the US, novel model parameters are described and then estimated for the first time to capture real-time dynamics of hepatocytes in the presence and absence of IH condition. The results may allow physicians to estimate the extent of liver damage in an IH patient based on their enzyme levels and receive faster treatment on a real-time basis.

Interaction between anesthetic conditioning and ischemic preconditioning on metabolic function after hepatic ischemia-reperfusion in rabbits

BACKGROUND

Both anesthetic-induced and ischemic preconditioning are protective against hepatic ischemia-reperfusion injury. However, the effects of these preventive methods on the metabolic function remain to be elucidated. We investigated the anesthetic conditioning and ischemic preconditioning on the metabolic function of the rabbit model of hepatic ischemia-reperfusion.

METHODS

After approval by the institutional animal care and use committee, 36 Japanese White rabbits underwent partial hepatic ischemia for 90 min either under sevoflurane or propofol anesthesia. All the rabbits underwent 90 min of hepatic ischemia, and half of the rabbits in each group underwent additional 10-min ischemia and 10-min reperfusion before index ischemia. Hepatic microvascular blood flow was intermittently measured during reperfusion period, and galactose clearance, serum aminotransferase activities, and lactate concentrations were determined 180 min after reperfusion.

RESULTS

Neither anesthetic conditioning with sevoflurane nor ischemic preconditioning altered hepatic microvascular blood flow during reperfusion and serum transaminase activities after reperfusion. However, galactose clearance of reperfused liver was significantly higher under sevoflurane anesthesia than propofol (0.016 ± 0.005/min vs. 0.011 ± 0.004/min). Statistically significant interaction between anesthetic choice and application of ischemic preconditioning suggests that the ischemic preconditioning is selectively protective under propofol anesthesia. Increase of blood lactate concentration was significantly suppressed under sevoflurane anesthesia compared to propofol (1.5 ± 0.8 vs. 3.9 ± 1.4 mmol/l) without any statistically significant interaction with the application of ischemic preconditioning.

CONCLUSION

Sevoflurane attenuated the decrease of galactose clearance and increase of the blood lactate after reperfusion compared to propofol. Application of ischemic preconditioning was significantly protective under propofol anesthesia.

Preserving low perfusion during surgical liver blood inflow control prevents hepatic microcirculatory dysfunction and irreversible hepatocyte injury in rats

Hepatic ischaemia/reperfusion (I/R) injury is of primary concern during liver surgery. We propose a new approach for preserving low liver blood perfusion during hepatectomy either by occlusion of the portal vein (OPV) while preserving hepatic artery flow or occlusion of the hepatic artery while limiting portal vein (LPV) flow to reduce I/R injury. The effects of this approach on liver I/R injury were investigated. Rats were randomly assigned into 4 groups: sham operation, occlusion of the portal triad (OPT), OPV and LPV. The 7-day survival rate was significantly improved in the OPV and LPV groups compared with the OPT group. Microcirculatory liver blood flow recovered rapidly after reperfusion in the OPV and LPV groups but decreased further in the OPT group. The OPV and LPV groups also showed much lower ALT and AST levels, Suzuki scores, inflammatory gene expression levels, and parenchymal necrosis compared with the OPT group. An imbalance between the expression of vasoconstriction and vasodilation genes was observed in the OPT group but not in the OPV or LPV group. Therefore, preserving low liver blood perfusion by either the OPV or LPV methods during liver surgery is very effective for preventing hepatic microcirculatory dysfunction and hepatocyte injury.

Sanguineous normothermic machine perfusion improves hemodynamics and biliary epithelial regeneration in donation after cardiac death porcine livers

The effects of normothermic machine perfusion (NMP) on the postreperfusion hemodynamics and extrahepatic biliary duct histology of donation after cardiac death (DCD) livers after transplantation have not been addressed thoroughly and represent the objective of this study. Ten livers (5 per group) with 60 minutes of warm ischemia were preserved via cold storage (CS) or sanguineous NMP for 10 hours, and then they were reperfused for 24 hours with whole blood in an isolated perfusion system to simulate transplantation. In our experiment, the arterial and portal vein flows were stable in the NMP group during the entire reperfusion simulation, whereas they decreased dramatically in the CS group after 16 hours of reperfusion (P < 0.05); these findings were consistent with severe parenchymal injury. Similarly, significant differences existed between the CS and NMP groups with respect to the release of hepatocellular enzymes, the volume of bile produced, and the levels of enzymes released into bile (P < 0.05). According to histology, CS livers presented with diffuse hepatocyte congestion, necrosis, intraparenchymal hemorrhaging, denudated biliary epithelium, and submucosal bile duct necrosis, whereas NMP livers showed very mild injury to the liver parenchyma and biliary architecture. Most importantly, Ki-67 staining in extrahepatic bile ducts showed biliary epithelial regeneration. In conclusion, our findings advance the knowledge of the postreperfusion events that characterize DCD livers and suggest NMP as a beneficial preservation modality that is able to improve biliary regeneration after a major ischemic event and may prevent the development of ischemic cholangiopathy in the setting of clinical transplantation.

Effect of the pringle maneuver on tumor recurrence of hepatocellular carcinoma after curative resection (EPTRH): a randomized, prospective, controlled multicenter trial

BACKGROUND

Hepatic resection is currently still the best choice of therapeutic strategies for liver cancer, but the long-term survival rate after surgery is unsatisfactory. Most patients develop intra- and/or extrahepatic recurrence. The reasons for this high recurrence rate are not entirely clear. Recent studies have indicated that ischemia-reperfusion injury to the liver may be a significant factor promoting tumor recurrence and metastasis in animal models. If this is also true in humans, the effects of the Pringle maneuver, which has been widely used in hepatectomy for the past century, should be examined. To date, there are no reported data or randomized controlled studies examining the relationship between use of the Pringle maneuver and local tumor recurrence. We hypothesize that the long-term prognosis of patients with liver cancer could be worsened by use of the Pringle maneuver due to an increase in the rate of tumor recurrence in the liver remnant. We designed a multicenter, prospective, randomized surgical trial to test this hypothesis.

METHODS

At least 498 eligible patients from five participating centers will be enrolled and randomized into either the Pringle group or the non-Pringle group in a ratio of 1:1 using a permuted-blocks randomization protocol. After the completion of surgical intervention, patients will be included in a 3-year follow-up program.

DISCUSSION

This multicenter surgical trial will examine whether the Pringle maneuver has a negative effect on the long-term outcome of hepatocellular carcinoma patients. The trial will also provide information about prognostic differences, safety, advantages and disadvantages between Pringle and non-Pringle surgical procedures. Ultimately, the results will increase the available information about the effects of ischemia-reperfusion injury on tumor recurrence, which will be of immense benefit to general surgery.

TRIAL REGISTRATION

http://www.clinicaltrials.gov NCT00725335.

Regulation of hepatic blood flow: The hepatic arterial buffer response revisited

The interest in the liver dates back to ancient times when it was considered to be the seat of life processes. The liver is indeed essential to life, not only due to its complex functions in biosynthesis, metabolism and clearance, but also its dramatic role as the blood volume reservoir. Among parenchymal organs, blood flow to the liver is unique due to the dual supply from the portal vein and the hepatic artery. Knowledge of the mutual communication of both the hepatic artery and the portal vein is essential to understand hepatic physiology and pathophysiology. To distinguish the individual importance of each of these inflows in normal and abnormal states is still a challenging task and the subject of ongoing research. A central mechanism that controls and allows constancy of hepatic blood flow is the hepatic arterial buffer response. The current paper reviews the relevance of this intimate hepatic blood flow regulatory system in health and disease. We exclusively focus on the endogenous interrelationship between the hepatic arterial and portal venous inflow circuits in liver resection and transplantation, as well as inflammatory and chronic liver diseases. We do not consider the hepatic microvascular anatomy, as this has been the subject of another recent review.

Ischemic preconditioning-induced hyperperfusion correlates with hepatoprotection after liver resection

AIM: To characterize the impact of the Pringle maneuver (PM) and ischemic preconditioning (IP) on total blood supply to the liver following hepatectomies.

METHODS: Sixty one consecutive patients who underwent hepatic resection under inflow occlusion were randomized either to receive PM alone (n = 31) or IP (10 min of ischemia followed by 10 min of reperfusion) prior to PM (n = 30). Quantification of liver perfusion was measured by Doppler probes at the hepatic artery and portal vein at various time points after reperfusion of remnant livers.

RESULTS: Occlusion times of 33 ± 12 min (mean ± SD) and 34 ± 14 min and the extent of resected liver tissue (2.7 segments) were similar in both groups. In controls (PM), on reperfusion of liver remnants for 15 min, portal perfusion markedly decreased by 29% while there was a slight increase of 8% in the arterial blood flow. In contrast, following IP + PM the portal vein flow remained unchanged during reperfusion and a significantly increased arterial blood flow (+56% vs baseline) was observed. In accordance with a better postischemic blood supply of the liver, hepatocellular injury, as measured by alanine aminotransferase (ALT) levels on day 1 was considerably lower in group B compared to group A (247 ± 210 U/I vs 550 ± 650 U/I, P < 0.05). Additionally, ALT levels were significantly correlated to the hepatic artery inflow.

CONCLUSION: IP prevents postischemic flow reduction of the portal vein and simultaneously increases arterial perfusion, suggesting that improved hepatic macrocirculation is a protective mechanism following hepatectomy.

The hepatic microcirculation: mechanistic contributions and therapeutic targets in liver injury and repair

The complex functions of the liver in biosynthesis, metabolism, clearance, and host defense are tightly dependent on an adequate microcirculation. To guarantee hepatic homeostasis, this requires not only a sufficient nutritive perfusion and oxygen supply, but also a balanced vasomotor control and an appropriate cell-cell communication. Deteriorations of the hepatic homeostasis, as observed in ischemia/reperfusion, cold preservation and transplantation, septic organ failure, and hepatic resection-induced hyperperfusion, are associated with a high morbidity and mortality. During the last two decades, experimental studies have demonstrated that microcirculatory disorders are determinants for organ failure in these disease states. Disorders include 1) a dysregulation of the vasomotor control with a deterioration of the endothelin-nitric oxide balance, an arterial and sinusoidal constriction, and a shutdown of the microcirculation as well as 2) an overwhelming inflammatory response with microvascular leukocyte accumulation, platelet adherence, and Kupffer cell activation. Within the sequelae of events, proinflammatory mediators, such as reactive oxygen species and tumor necrosis factor-alpha, are the key players, causing the microvascular dysfunction and perfusion failure. This review covers the morphological and functional characterization of the hepatic microcirculation, the mechanistic contributions in surgical disease states, and the therapeutic targets to attenuate tissue injury and organ dysfunction. It also indicates future directions to translate the knowledge achieved from experimental studies into clinical practice. By this, the use of the recently introduced techniques to monitor the hepatic microcirculation in humans, such as near-infrared spectroscopy or orthogonal polarized spectral imaging, may allow an early initiation of treatment, which should benefit the final outcome of these critically ill patients.

Phosphodiesterase-5 inhibitors have distinct effects on the hemodynamics of the liver

Background

The NO - cGMP system plays a key role in the regulation of sinusoidal tonus and liver blood flow with phosphodiesterase-5 (PDE-5) terminating the dilatory action of cGMP. We, therefore, investigated the effects of PDE-5 inhibitors on hepatic and systemic hemodynamics in rats.

Methods

Hemodynamic parameters were monitored for 60 min. after intravenous injection of sildenafil and vardenafil [1, 10 and 100 μg/kg (sil1, sil10, sil100, var1, var10, var100)] in anesthetized rats.

Results

Cardiac output and heart rate remained constant. After a short dip, mean arterial blood pressure again increased. Systemic vascular resistance transiently decreased slightly. Changes in hepatic hemodynamic parameters started after few minutes and continued for at least 60 min. Portal (var10 -31%, sil10 -34%) and hepatic arterial resistance (var10 -30%, sil10 -32%) decreased significantly (p < 0.05). At the same time portal venous (var10 +29%, sil10 +24%), hepatic arterial (var10 +34%, sil10 +48%), and hepatic parenchymal blood flow (var10 +15%, sil10 +15%) increased significantly (p < 0.05). The fractional liver blood flow (total liver flow/cardiac output) increased significantly (var10 26%, sil10 23%). Portal pressure remained constant or tended to decrease. 10 μg/kg was the most effective dose for both PDE-5 inhibitors.

Conclusion

Low doses of phosphodiesterase-5 inhibitors have distinct effects on hepatic hemodynamic parameters. Their therapeutic use in portal hypertension should therefore be evaluated.

Thoracic epidural anesthesia reverses sepsis-induced hepatic hyperperfusion and reduces leukocyte adhesion in septic rats

INTRODUCTION

Liver dysfunction is a common feature of severe sepsis and is associated with a poor outcome. Both liver perfusion and hepatic inflammatory response in sepsis might be affected by sympathetic nerve activity. However, the effects of thoracic epidural anesthesia (TEA), which is associated with regional sympathetic block, on septic liver injury are unknown. Therefore, we investigated hepatic microcirculation and inflammatory response during TEA in septic rats.

METHODS

Forty-five male Sprague-Dawley-rats were instrumented with thoracic epidural catheters and randomized to receive a sham procedure (Sham), cecal ligation and puncture (CLP) without epidural anesthesia (Sepsis) and CLP with epidural infusion of 15 ul/h bupivacaine 0.5% (Sepsis + TEA). All animals received 2 ml/100 g/h NaCl 0.9%. In 24 (n = 8 in each group) rats, sinusoidal diameter, loss of sinusoidal perfusion and sinusoidal blood flow as well as temporary and permanent leukocyte adhesion to sinusoidal and venolar endothelium were recorded by intravital microscopy after 24 hours. In 21 (n = 7 in each group) separate rats, cardiac output was measured by thermodilution. Blood pressure, heart rate, serum transaminase activity, serum TNF-alpha concentration and histologic signs of tissue injury were recorded.

RESULTS

Whereas cardiac output remained constant in all groups, sinusoidal blood flow increased in the Sepsis group and was normalized in rats subjected to sepsis and TEA. Sepsis-induced sinusoidal vasoconstriction was not ameliorated by TEA. In the Sepsis + TEA group, the increase in temporary venolar leukocyte adherence was blunted. In contrast to this, sinusoidal leukocyte adherence was not ameliorated in the Sepsis + TEA group. Sepsis-related release of TNF-alpha and liver tissue injury were not affected by Sepsis + TEA.

CONCLUSIONS

This study demonstrates that TEA reverses sepsis-induced alterations in hepatic perfusion and ameliorates hepatic leukocyte recruitment in sepsis.

Are angiotensin II receptor antagonists useful strategies in steatotic and nonsteatotic livers in conditions of partial hepatectomy under ischemia-reperfusion?

We examined whether angiotensin (Ang) II receptor antagonists could be considered a therapeutic strategy in steatotic and nonsteatotic livers in conditions of partial hepatectomy under ischemia-reperfusion (I/R), which is commonly applied in clinical practice to reduce blood loss. We report that Ang II type I receptor (AT1R) antagonist, but not Ang II type II receptor (AT2R) antagonist, increased regeneration in nonsteatotic livers. In the presence of steatosis, both AT1R and AT2R antagonists increased liver regeneration. This effect was stronger when the two were combined. Neither of the Ang II receptor antagonists protected nonsteatotic livers against damage. Only the AT1R antagonist, through nitric oxide inhibition, reduced damage in steatotic livers. The combination of the AT1R and AT2R antagonists in steatotic livers conferred a similar degree of protection to AT1R antagonist alone. Herein, we show that p38 mitogen-activated protein kinase (p38) was a key mechanism in the regeneration induced by the Ang II receptor antagonists in both liver types because when this signaling pathway was inhibited, the beneficial effects of the Ang II receptor antagonists on liver regeneration disappeared, regardless of hepatocyte growth factor or transforming growth factor beta-hepatic levels. In conclusion, in conditions of partial hepatectomy under I/R, the AT1R antagonist for nonsteatotic livers and the AT1R and AT2R antagonists for steatotic livers improved regeneration in the remnant liver through p38 activation. In addition, the combination of the AT1R and AT2R antagonists in steatotic livers led to stronger liver regeneration than either antagonists used separately and also provided the same protection against damage as that afforded by AT1R antagonist alone.

Portal vein pulsatility index is a more important indicator than congestion index in the clinical evaluation of right heart function

AIM: To study the changes of portal blood flow in congestive heart failure.

METHODS: We studied the congestion index (CI) and portal vein pulsatility index (PI) in patients with varied degrees of congestive heart failure using ultrasonic Doppler. Ten patients with mean right atrial pressure (RA) < 10 mmHg were classified as group 1 and the remaining 10 patients with RA ≥ 10 mmHg as group 2.

RESULTS: There were no difference on cardiac index (HI, P = 0.28), aortic pressure (AO, P  = 0.78), left ventricular end-diastolic pressure (LVED, P  = 0.06), maximum portal blood velocity (V_max, P  = 0.17), mean portal blood velocity (V_mean, P = 0.15) and portal blood flow volume (PBF, P  = 0.95) between the two groups. Group 2 patients had higher pulmonary wedge pressure (PW, 29.9 ± 9.3 mmHg vs 14.6 ± 7.3 mmHg, P = 0.002), pulmonary arterial pressure (PA, 46.3 ± 13.2 mmHg vs 25.0±8.2 mmHg, P =0.004), RA (17.5±5.7 mmHg vs 4.7 ± 2.4 mmHg, P  < 0.001), right ventricular end-diastolic pressure (RVED, 18.3 ± 5.6 mmHg vs 6.4 ± 2.7 mmHg, P < 0.001), CI (8.7 ± 2.4 vs 5.8 ± 1.2, P  = 0.03), and PI (87.8 ± 32.3% vs 27.0 ± 7.4%, P  < 0.001) than Group 1. CI was correlated with PI (P  < 0.001), PW (P  < 0.001), PA (P  < 0.001), RA (P  = 0.043), RVED (P  = 0.005), HI (P  < 0.001), AO (P  < 0.001), CO (P  < 0.001), LVED (P  < 0.001), V_max (P  < 0.001), V_mean (P  < 0.001), cross-sectional area of the main portal vein (P  < 0.001) and PBF (P  < 0.001). CI could be as high as 8.3 in patients with RA < 10 mmHg and as low as 5.9 in those with RA ≥ 10 mmHg.

CONCLUSION: Our data show that RI is a more significant indicator than CI in the clinical evaluation of high RA ≥ 10 mmHg, whereas CI is better than PI in the assessment of left heart function.

Mild hypothermia protects liver against ischemia and reperfusion injury

AIM: To determine whether mild hypothermia could protect liver against ischemia and reperfusion injury in pigs.

METHODS: Twenty-four healthy pigs were randomly divided into normothermia, mild hypothermia and normal control groups. The experimental procedure consisted of temporary interruption of blood flow to total hepatic lobe for different lengths of time and subsequent reperfusion. Hepatic tissue oxygen pressure (P_tiO₂) and aspartate aminotransferase (AST) values were evaluated, and ultrastructural analysis was carried out for all samples.

RESULTS: Serum AST was significantly lower, and hepatic P_tiO₂ values were significantly higher in the mild hypothermia group than in the normothermia group during liver ischemia-reperfusion periods (P = 0.032, P = 0.028). Meanwhile, the histopathologic injury of liver induced by ischemia-reperfusion was significantly improved in the mild hypothermia group, compared with that in the normothermia group.

CONCLUSION: Mild hypothermia can protect the liver from ischemia-reperfusion injury in pigs.

Identification of differentially expressed genes after partial rat liver ischemia/reperfusion by suppression subtractive hybridization

AIM: To identify potential diagnostic target genes in early reperfusion periods following warm liver ischemia before irreversible liver damage occurs.

METHODS: We used two strategies (SSH suppression subtractive hybridization and hybridization of cDNA arrays) to determine early changes in gene expression profiles in a rat model of partial WI/R, comparing postischemic and adjacent nonischemic liver lobes. Differential gene expression was verified (WI/R; 1 h/2 h) and analyzed in more detail after warm ischemia (1 h) in a reperfusion time kinetics (0, 1, 2 and 6 h) and compared to untreated livers by Northern blot hybridizations. Protein expression was examined on Western blots and by immunohistochemistry for four differentially expressed target genes (Hsp70, Hsp27, Gadd45a and IL-1rI).

RESULTS: Thirty-two individual WI/R target genes showing altered RNA levels after confirmation by Northern blot analyzes were identified. Among them, six functionally uncharacteristic expressed sequences and 26 known genes (12 induced in postischemic liver lobes, 14 with higher transcriptional expression in adjacent nonischemic liver lobes). Functional categories of the verified marker genes indicate on the one hand cellular stress and tissue damage but otherwise activation of protective cellular reactions (AP-1 transcription factors, apoptosis related genes, heat shock genes). In order to assign the transcriptional status to the biological relevant protein level we demonstrated that Hsp70, Hsp27, Gadd45a and IL-1rI were clearly up-regulated comparing postischemic and untreated rat livers, suggesting their involvement in the WI/R context.

CONCLUSION: This study unveils a WI/R response gene set that will help to explore molecular pathways involved in the tissue damage after WI/R. In addition, these genes especially Hsp70 and Gadd45a might represent promising new candidates indicating WI/R liver damage.

Percentage of peak-to-peak pulsatility of portal blood flow can predict right-sided congestive heart failure

AIM: To study the change of portal blood flow for the prediction of the status of right-sided heart failure by using non-invasive way.

METHODS: We studied 20 patients with rheumatic and atherosclerotic heart diseases. All the patients had constant systemic blood pressure and body weight 1 week prior to the study. Cardiac index (CI), left ventricular end-diastolic pressure (LVEDP), mean aortic pressure (AOP), pulmonary wedge pressure (PWP), mean pulmonary arterial pressure (PAP), mean right atrial pressure (RAP), right ventricular end-diastolic pressure (RVEDP) were recorded during cardiac catheterization. Ten patients with RAP < 10 mmHg were classified as Group 1. The remaining 10 patients with RAP ≥ 10 mmHg were classified as Group 2. Portal blood velocity profiles were studied using an ultrasonic Doppler within 12 h after cardiac catheterization.

RESULTS: CI, AOP, and LVEDP had no difference between two groups. Patients in Group 1 had normal PWP (14.6 ± 7.3 mmHg), PAP (25.0 ± 8.2 mmHg), RAP (4.7 ± 2.4 mmHg), and RVEDP (6.4 ± 2.7 mmHg). Patients in Group 2 had increased PWP (29.9 ± 9.3 mmHg), PAP (46.3 ± 13.2 mmHg), RAP (17.5 ± 5.7 mmHg), and RVEDP (18.3 ± 5.6 mmHg) (P < 0.001). Mean values of maximum portal blood velocity (Vmax), mean portal blood velocity (Vmean), cross-sectional area (Area) and portal blood flow volume (PBF) had no difference between 2 groups. All the patients in Group 1 had a continuous antegrade portal flow with a mean percentage of peak-to-peak pulsatility (PP) 27.0% ± 8.9% (range: 17% - 40%). All the patients in Group 2 had pulsatile portal flow with a mean PP 86.6 ± 45.6 (range: 43%-194%). One patient had a transient stagnant and three patients had a transient hepatofugal portal flow, which occurred mainly during the ventricular systole. Vmax, Vmean and PBF had a positive correlation with CO (P < 0.001) but not with AOP, LVEDP, PWP, PAP, RAP, and RVEDP. PP showed a good correlation (P < 0.001) with PWP, PAP, RAP, and RVEDP but not with CI, AOP, and LVEDP. All the patients with PP > 40% had a right-sided heart failure with a RAP = 10 mmHg.

CONCLUSION: The measurement of PP change is a simple and non-invasive way to identify patients with right heart failure.