Pathophysiology of portal hypertension and variceal bleeding

The potential lethality of caput medusae

While gastro-oesophageal varices commonly complicate portal hypertension and may be a life-threatening condition, fatal haemorrhaging from cirrhosis-related caput medusae has seldom been described in the scientific literature. This article documents a rare death due to the rupture of a varix in the umbilical area. This case raises a number of points for medico-legal discussion, such as the negative consequences of an erroneous cause of death in evaluating medical malpractice cases and the importance of a thorough external examination of the body in order to ensure this type of vascular lesion is not overlooked.

Relationship between hemodynamic parameters and portal venous pressure in cirrhosis patients with portal hypertension

Cirrhosis caused by viral and alcoholic hepatitis is an essential cause of portal hypertension (PHT). The incidence of PHT complication is directly proportional to portal venous pressure (PVP), and the clinical research of PVP and its hemodynamic indexes is of great significance for deciding the treatment strategy of PHT. Various techniques are currently being developed to decrease portal pressure but hemodynamic side effects may occur. In this article, the hemodynamic indexes of cirrhotic PHT patients were studied to explore the correlation between the index and PVP and to evaluate the clinical value of Doppler ultrasound in measuring PVP in patients with PHT. This was achieved by selecting 90 cirrhotic PHT patients who underwent transjugular intrahepatic portosystemic shunt in our hospital from June 2015 to September 2019. Fifty healthy people who had a physical examination in the hospital in the same period were selected as the control group. The liver hemodynamic parameters of two groups were measured by Doppler ultrasound, and the cirrhotic PHT patients were graded by the Child–Pugh grading method to evaluate the liver function and measure the PVP value. The results showed that both the central portal vein velocity (PVV) and splenic vein velocity (SVV) of the PHT group were lower than those of the control group. Also, the portal vein diameter (PVD), portal venous flow and splenic vein diameter (SVD) were higher than those of the control group (all Ps < 0.05). Among liver function graded PHT patients, the PVD, PVV, SVD and SVV were significantly different (all Ps < 0.05). Furthermore, the PVP of patients with liver function grades A, B and C was 38.9 ± 1.4, 40.6 ± 5.1 and 42.5 ± 4.8 cmH₂O, respectively, with a significant difference. It can be concluded from this study that Doppler ultrasound can be used as a tool for clinical assessment of PHT in cirrhosis patients. Doppler ultrasound showed a good prospect in noninvasive detection of PHT in cirrhosis; however, this technique needs application on large sample population study to validate the results.

Fatal hemorrhage from a periumbilical wound: Stabbing or hemorrhage from a caput medusae?

Varices are the main clinical manifestation of portal hypertension, and their bleeding is the predominant cause of mortality from this condition. Periumbilical varices are known as "caput medusae." Reports of their bleeding are rare, with only three fatal cases described in the literature. The antemortem diagnosis is relatively simple, while the postmortem diagnosis is more complex. This paper is the first report of fatal hemorrhage from a caput medusae for which the diagnosis was made postmortem, thanks to a complete diagnostic process including scene and circumstances, medical history, and autopsy with detailed histology. The circumstantial analysis showed the presence of a large amount of blood at the scene, blood which originated from a small abdominal wound; an analysis of the subject's clinical data reported that he was affected by portal hypertension. The autopsy revealed some dilated and convoluted veins in the subcutaneous tissue of the umbilical region; a fistula between these veins and the abdominal wound was detected. The histological study confirmed the presence of periumbilical varices, one of them ruptured and connected with the overlying skin. The cause of death was attributed to a massive hemorrhage generated by a periumbilical varix in a patient affected by portal hypertension.

TIPS to the rescue: Preoperative Transjugular Intrahepatic Portosystemic Shunt (TIPS) placement in a patient with caput medusae and colon cancer

Abdominal surgery in patients with cirrhosis and portal hypertension remains a challenge due to higher risk of morbidity and mortality. Preoperative elective transjugular intrahepatic portosystemic shunt (TIPS) is increasingly being used in these patient population. Herein, we report a case of 65-year-old male with biopsy-proven ascending colon cancer and cirrhosis. As a sequalae of portal hypertension, patient also had large caput medusae which posed significant challenge to the surgical approach for resection of the colon cancer. The patient was managed initially with placement of TIPS to decompress the portal pressures and caput medusae and allow safe surgical field for curative resection of the colon cancer. Following this, the patient underwent uneventful laparoscopic right hemicolectomy.

A case of fatal cutaneous caput medusae hemorrhage

Alcoholic liver cirrhosis leads to portal venous hypertension, which can result in a caput medusae formation. Life-threatening hemorrhage from a ruptured caput medusae vein is a rare complication. It is crucial to stop the bleeding promptly. A transjugular intrahepatic portosystemic shunt is considered potentially lifesaving.

Impact of Helicobacter pylori Infection on Gastric Variceal Bleeding among Patients with Liver Cirrhosis

BACKGROUND AND AIMS

Currently, it is well known that Helicobacter pylori- (H. pylori-) related peptic ulcer is one of the main causes of nonvariceal bleeding in cirrhotic patients. However, there is a lack of data to identify the exact effect of H. pylori infection on variceal bleeding. This study was conducted to identify the impact of H. pylori infection on gastric variceal bleeding in cirrhotic patients.

PATIENTS AND METHODS

76 cirrhotic patients with gastric varices were included in this prospective study and divided into 2 groups: nonbleeding gastric varices (32 patients) and bleeding gastric varices (44 patients). The fasting serum gastrin level was measured. Mucosal biopsies from the gastric body and antrum were examined to determine the patterns of gastritis and the presence of H. pylori.

RESULTS

The frequency of H. pylori infection in the studied patients was 59.2%. There were significant differences between both groups regarding liver decompensation (P = 0.001), red color sign over gastric varices (P = 0.0011), prevalence of H. pylori infection (P = 0.0049), histological patterns of gastritis (P = 0.0069), and serum gastrin level (P = 0.0200). By multivariate analysis, Child C cirrhosis, red color sign over gastric varices, and H. pylori-induced follicular gastritis were independent risk factors for bleeding from gastric varices.

CONCLUSION

H. pylori-induced follicular gastritis is considered as an additional risk factor for bleeding from gastric varices.

The Gastrointestinal Circulation: Physiology and Pathophysiology

The gastrointestinal (GI) circulation receives a large fraction of cardiac output and this increases following ingestion of a meal. While blood flow regulation is not the intense phenomenon noted in other vascular beds, the combined responses of blood flow, and capillary oxygen exchange help ensure a level of tissue oxygenation that is commensurate with organ metabolism and function. This is evidenced in the vascular responses of the stomach to increased acid production and in intestine during periods of enhanced nutrient absorption. Complimenting the metabolic vasoregulation is a strong myogenic response that contributes to basal vascular tone and to the responses elicited by changes in intravascular pressure. The GI circulation also contributes to a mucosal defense mechanism that protects against excessive damage to the epithelial lining following ingestion of toxins and/or noxious agents. Profound reductions in GI blood flow are evidenced in certain physiological (strenuous exercise) and pathological (hemorrhage) conditions, while some disease states (e.g., chronic portal hypertension) are associated with a hyperdynamic circulation. The sacrificial nature of GI blood flow is essential for ensuring adequate perfusion of vital organs during periods of whole body stress. The restoration of blood flow (reperfusion) to GI organs following ischemia elicits an exaggerated tissue injury response that reflects the potential of this organ system to generate reactive oxygen species and to mount an inflammatory response. Human and animal studies of inflammatory bowel disease have also revealed a contribution of the vasculature to the initiation and perpetuation of the tissue inflammation and associated injury response.

Effect of Helicobacter pylori infection on esophagogastric variceal bleeding in patients with liver cirrhosis and portal hypertension

BACKGROUND AND AIMS

Bleeding from esophageal and gastric varices is a fatal event in patients with liver cirrhosis and portal hypertension. However, the effects of Helicobacter pylori (H. pylori) infection on esophagogastric variceal bleeding are not known. The present study was aimed to elucidate the role of H. pylori infection in esophagogastric variceal bleeding.

METHODS

The subjects were 196 cirrhotic patients who were admitted to the Kurume University Hospital to treat their esophagogastric varices consisted of 95 with acute bleeding and 101 with nonbleeding but high risk of bleeding. For the diagnosis of H. pylori infection, a (13) C-urea breath test was used, and serum pepsinogen (PG) I and II levels and the PG I/II ratio were also measured.

RESULTS

Esophagogastric variceal bleeding was seen in 34.9% (n = 30) of the H. pylori-infected patients (n = 86) and in 59.1% (n = 65) of the noninfected patients (n = 110) (P < 0.0007). There was no significant difference in the infection rate between the bleeding sites of the esophagus and the stomach. The serum PG I and II levels and the PG I/II ratio were 65.6 ng/dL, 14.7 ng/dL, and 4.4, respectively, for the bleeding patients (n = 95), and 43.7 ng/dL, 17.7 ng/dL, and 3.1 for the nonbleeding patients (n = 101). Thus, the nonbleeding patients had significantly higher rate of H. pylori infection and lower acid secretion than bleeding patients (0.001). In addition, multivariate logistic regression analysis showed a significant negative association between H. pylori infection and esophagogastric variceal bleeding.

CONCLUSIONS

These results suggest that H. pylori infection has a protective effect against esophagogastric variceal bleeding through the induction of gastric mucosal atrophy and concomitant hypoacidity.

The wound-healing response and upregulated embryonic mechanisms: brothers-in-arms forever

The cutaneous wound-healing reaction occurs in overlapping but inter-related phases, which ultimately result in fibrosis. The pathophysiological mechanisms involved in fibrotic diseases, including organ-related and even systemic diseases, such as systemic sclerosis, could represent the successive systemic upregulation of extraembryonic-like phenotypes, that is, amniotic and vitelline phenotypes. These two extraembryonic-like phenotypes act on the injured tissue to induce a process similar to gastrulation, which occurs during the early phases of embryo development. The amniotic-like phenotype plays a leading role in the development of neurogenic responses with significant hydroelectrolytic alterations that essentially represent the development of open microcirculation within the injured tissue. In turn, through the overlapping expression of a vitelline-like phenotype, a bone marrow-related response is produced. Interstitial infiltration by molecular and cellular mediators contributed by amniotic- and vitelline-like functions provides the functional and metabolic autonomy needed for inducing new tissue formation through mechanisms similar to those that act in gastrulation during the early phases of embryonic development. Thus, while a new tissue is formed, it quickly evolves into fibrotic tissue because of premature senescence. Mechanisms related to extraembryonic-like functions have been suggested in the following physiological and pathological processes: embryonic development; wound-healing reactions occurring during adult life; and senescence. The existence of this sort of basic self-organizing fractal-like functional pattern is an essential characteristic of our way of life.

Splenic elasticity measured with real-time tissue elastography is a marker of portal hypertension

PURPOSE

To prospectively correlate spleen elasticity and degree of portal hypertension estimated with the hepatic venous pressure gradient (HVPG) and to evaluate splenic elasticity as a predictor of gastroesophageal varices.

MATERIALS AND METHODS

The institutional review board approved this study, and patients provided written informed consent. In a pilot study of 60 patients with chronic liver damage, the authors measured liver and spleen elasticity with real-time tissue elastography (RTE), obtained serum markers related to fibrosis, examined hepatic and splenic blood flow with duplex Doppler ultrasonography, estimated HVPG, and performed upper gastrointestinal endoscopy. Then, with use of thresholds determined in the pilot study, the authors conducted a validation trial with another 210 patients, performing all studies except the measurement of HPVG. The relationship between HVPG and the other parameters was analyzed. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) in the diagnosis of gastroesophageal varices were calculated by using cutoff values obtained from receiver operating characteristic curves.

RESULTS

Among the parameters associated with HVPG, correlation was closest with splenic elasticity (R = 0.854, P < .0001). When 8.24 was selected as the cutoff of splenic elasticity for predicting HVPG of more than 10 mm Hg, the accuracy of diagnosing gastroesophageal varix was 90% (sensitivity, 96%; specificity, 85%; PPV, 83%; NPV, 97%). The results of the validation trial showed that the 8.24 cutoff for splenic elasticity was associated with a diagnostic accuracy of 94.8% (sensitivity, 98%; specificity, 93.8%; PPV, 82.1%; NPV, 99.4%) for gastroesophageal varices.

CONCLUSION

Splenic elasticity determined with RTE is the most closely associated parameter for evaluating HVPG and is useful as a clinical marker of portal hypertension and a predictive marker of gastroesophageal varices.

CT portography with gastric variceal volume measurements in the evaluation of endoscopic therapeutic efficacy of tissue adhesive injection into gastric varices: a pilot study

BACKGROUND

N-butyl-2-cyanoacrylate (NBCA) injection is used for treating gastric varices (GV). Determining the degree of obliteration of GV is not readily evident at endoscopy.

AIMS

The aim of this study was to evaluate CT portography with gastric variceal volume calculations to assess endoscopic therapeutic efficacy of NBCA injection.

METHODS

The study design is a retrospective series pilot study. The setting is a single, tertiary care academic medical center. Ten patients underwent esophagogastroduodenoscopy (EGD) with NBCA injection of GV and had biphasic CT scans performed before and after injection therapy. Based on portal venous images, 3D reconstruction and semi-automated volume calculations of GV were performed. Pre and post injection GV volume calculations were compared.

RESULTS

The mean pre-procedure GV volume was 89.84 cm3. Eight patients had significant improvement in GV volume from pre-treatment versus post-treatment (95.65 cm3 vs. 49.65 cm3, P-value 0.04). Pre-procedure GV volume was not significantly different in patients treated for active hemorrhage versus no hemorrhage (101.66 cm3 vs. 72.11 cm3, P-value 0.33). Two patients had a subsequent GV hemorrhage after NBCA injection. The mean residual GV volume in these patients versus those that did not re-bleed was significantly more (127.77 cm3 vs. 38.00 cm3, P-value 0.005).

CONCLUSIONS

CT portography with measurement of GV volume is a potentially useful tool in determining the therapeutic efficacy NBCA injection of GV. Patients with higher residual GV volumes are at increased risk of hemorrhage and may benefit from repeat injection to reach ideal GV volumes.

Inflammation: a way to understanding the evolution of portal hypertension

BACKGROUND

Portal hypertension is a clinical syndrome that manifests as ascites, portosystemic encephalopathy and variceal hemorrhage, and these alterations often lead to death.

HYPOTHESIS

Splanchnic and/or systemic responses to portal hypertension could have pathophysiological mechanisms similar to those involved in the post-traumatic inflammatory response.The splanchnic and systemic impairments produced throughout the evolution of experimental prehepatic portal hypertension could be considered to have an inflammatory origin. In portal vein ligated rats, portal hypertensive enteropathy, hepatic steatosis and portal hypertensive encephalopathy show phenotypes during their development that can be considered inflammatory, such as: ischemia-reperfusion (vasodilatory response), infiltration by inflammatory cells (mast cells) and bacteria (intestinal translocation of endotoxins and bacteria) and lastly, angiogenesis. Similar inflammatory phenotypes, worsened by chronic liver disease (with anti-oxidant and anti-enzymatic ability reduction) characterize the evolution of portal hypertension and its complications (hepatorenal syndrome, ascites and esophageal variceal hemorrhage) in humans.

CONCLUSION

Low-grade inflammation, related to prehepatic portal hypertension, switches to high-grade inflammation with the development of severe and life-threatening complications when associated with chronic liver disease.

The mast cell integrates the splanchnic and systemic inflammatory response in portal hypertension

Portal hypertension is a clinical syndrome that is difficult to study in an isolated manner since it is always associated with a greater or lesser degree of liver functional impairment. The aim of this review is to integrate the complications related to chronic liver disease by using both, the array of mast cell functions and mediators, since they possibly are involved in the pathophysiological mechanisms of these complications. The portal vein ligated rat is the experimental model most widely used to study this syndrome and it has been considered that a systemic inflammatory response is produced. This response is mediated among other inflammatory cells by mast cells and it evolves in three linked pathological functional systems. The nervous functional system presents ischemia-reperfusion and edema (oxidative stress) and would be responsible for hyperdynamic circulation; the immune functional system causes tissue infiltration by inflammatory cells, particularly mast cells and bacteria (enzymatic stress) and the endocrine functional system presents endothelial proliferation (antioxidative and antienzymatic stress) and angiogenesis. Mast cells could develop a key role in the expression of these three phenotypes because their mediators have the ability to produce all the aforementioned alterations, both at the splanchnic level (portal hypertensive enteropathy, mesenteric adenitis, liver steatosis) and the systemic level (portal hypertensive encephalopathy). This hypothetical splanchnic and systemic inflammatory response would be aggravated during the progression of the chronic liver disease, since the antioxidant ability of the body decreases. Thus, a critical state is produced, in which the appearance of noxious factors would favor the development of a dedifferentiation process protagonized by the nervous functional system. This system rapidly induces an ischemia-reperfusion phenotype with hydration and salinization of the body (hepatorenal syndrome, ascites) which, in turn would reduce the metabolic needs of the body and facilitate its temporary survival.

Evolutive phases of experimental prehepatic portal hypertension

Partial portal vein ligation is the experimental model most frequently used to study prehepatic portal hypertension. Different systemic and splanchnic biochemical and histological alterations in short-term (28-45 days) and long-term (12-14 months) evolutive phases which has been described in this experimental model suggest the existence of different pathophysiological mechanisms involved in their production. The enteropathy produced could develop in three phases: an early or acute phase with vasomotor hemodynamic alterations (ischemia-reperfusion associated with intestinal hyperemia, edema and oxidative stress); an intermediate phase with immunological alterations (mesenteric lymphadenopathy, increased mucosal infiltration by mast cells and the hepato-intestinal release of pro- and anti-inflammatory mediators); and a late or chronic phase with intestinal remodeling (vascular and epithelial). The alterations which are produced in these three evolutive phases make it possible to propose an inflammatory etiopathogeny for hypertensive portal enteropathy.

Portal hypertension: return to fetal life to re-attempt differentiation?

We speculate on the final meaning of the alterations that characterize portal hypertensive enteropathy. The similarity of these alterations with certain morphofunctional characteristics of prenatal splanchnic development makes it possible to hypothesize that the dedifferentiation with return to early stages of development could constitute a portal hypertension induced pathogenic mechanism.

Review article: the relevance of portal pressure and other risk factors in acute gastro-oesophageal variceal bleeding

Gastro-oesophageal variceal bleeding is the last step in a chain of events that starts with an increased portal pressure, and is followed by the formation and progressive dilatation of gastro-oesophageal varices. When the tension of the thin wall of the varices exceeds its elastic limit, the varices rupture and bleed. Wall tension is directly proportional to variceal pressure (which is a function of portal pressure) and variceal radius, and inversely related to the thickness of the variceal wall. The above facts explain why a high portal pressure (usually determined by the hepatic venous pressure gradient, or HVPG) and the presence at endoscopy of large varices with red wheals, red spots or diffuse redness on the varices (signalling a reduced wall thickness) correlate with the risk of bleeding.

Relationship of hemodynamic indices and prognosis in patients with liver cirrhosis

BACKGROUND

Hyperdynamic circulation due to reduced peripheral vascular resistance and increased cardiac output, and the development of portal hypertension are the hemodynamic changes observed in patients with liver cirrhosis. Such hemodynamic abnormalities appear in patients with late stage liver cirrhosis. Therefore, hemodynamic indices, which represent hyperdynamic circulation and portal hypertension, are significant for the prognosis of patients with liver cirrhosis. The aim of this study was to determine the hemodynamic indices associated with the prognosis of patients with liver cirrhosis.

METHODS

A total of 103 patients diagnosed with liver cirrhosis between December 1999 and June 2003, with a mean follow-up period of 73 weeks, ranging from 7 to 168 weeks, were recruited. Using Child-Pugh classification, the mean arterial pressure, heart rate and hepatic venous pressure gradient (HVPG) were measured. The indices of Doppler ultrasonography, including the portal and splenic venous flows, and the resistance of the hepatic, splenic, and renal arteries were also measured using the arterial pulsatility index (PI). The prognostic values of these indices were determined by their comparison with the patient survivals.

RESULTS

Significant hemodynamic indices for a bad prognosis were high HVPG (> or = 15 mmHg) and renal arterial PI (> or = 1.14)(p<0.05). A Child-Pugh score > or = 10 was important for a poor prognosis (p<0.05).

CONCLUSION

Severe portal hypertension (HVPG > or = 15 mmHg) and high renal arterial resistance (PI +/- 1.14) were valuable hemodynamic indices for the prognosis of patients with liver cirrhosis. Therefore, it was concluded that the measurement of these hemodynamic indices, in addition to the Child-Pugh classification, is helpful in the prognosis of patients with liver cirrhosis.

Comparison of Doppler ultrasonography and the hepatic venous pressure gradient in assessing portal hypertension in liver cirrhosis

BACKGROUND AND AIM

This prospective study aimed to determine whether Doppler ultrasonography can represent the hepatic venous pressure gradient (HVPG) as an assessment of the severity of portal hypertension and the response to terlipressin, which reduces the portal pressure in liver cirrhosis.

METHODS

The HVPG and the Doppler ultrasonographic parameters, such as the portal venous velocity and the splenic venous velocity, the pulsatility and the resistive index of the hepatic, splenic and renal arteries were measured in 138 patients with liver cirrhosis. The changes in the HVPG and the portal venous velocity after administering terlipressin were evaluated in 43 of the 138 patients. The patients who showed a reduction in the HVPG of more than 20% of the baseline were defined as responders to terlipressin.

RESULTS

None of the Doppler ultrasonographic parameters correlated with the HVPG. Both the HVPG (28.0 +/- 19.8%) and the portal venous velocity (29.7 +/- 13.2%) showed a significant reduction after terlipressin administration. However, the portal venous velocity decreased significantly, not only in the responders (31.0 +/- 12.0%) but also in the non-responders (25.2 +/- 16.4%).

CONCLUSIONS

Doppler ultrasonography does not represent the HVPG, and is therefore not suitable for replacing HVPG as a means of assessing the severity of portal hypertension and the response to drugs which reduce the portal pressure in liver cirrhosis.

Vascular imaging and interventional procedures in hepatic cirrhosis

Changes in the vascularization of the cirrhotic liver are related to the progression of the disease. Knowledge of normal hepatic vascular anatomy and anatomic is essential for understanding the altered hepatic circulation seen in cirrhosis. We analyze the changes in liver perfusion with special interest in the anatomic features that are important in interventional procedures. The indications, technical notes, and complications of transjugular liver biopsy, transiugular intrahepatic portosystemic shunt (TIPS), and embolization of hepatocellular carcinoma, are reviewed.

Altered thyroid status modulates portal pressure in normal rats

BACKGROUND & AIMS

Disturbances in thyroid function in humans and experimental animal models have been associated with alterations in liver function and portal circulation. We have previously shown that hypothyroidism can significantly reduce portal pressure in portal vein ligated rats as well as inhibit the development of cirrhosis and fulminant hepatic failure following toxic liver injury. The aim of this study was to determine the effects of increased and decreased thyroid function on portal pressure in rats with normal liver histology and portal circulation.

METHODS

Three groups of 12 Wistar rats each were studied over a 30 day period: euthyroid (Group 1), hyperthyroid (Group 2) and hypothyroid (Group 3). Hyperthyroidism was induced by subcutaneous injection of triiodothyronine (400 microg/100g body weight) every ten days during the study period. Hypothyroidism was induced by methimazole (0.04% in drinking water) from 2 weeks prior to and throughout the 30 day study. Serum triiodothyronine (T3) and thyroid stimulating hormone (TSH) levels were determined to confirm the induction of hyper- and hypothyroidism. Portal pressure was assessed by direct catheterization of the portal vein prior to sacrifice. Indirect confirmation of changes in portal circulation was obtained by determining splenic weight at the time of sacrificing the animals. Animals were sacrificed at 10 day intervals throughout the 30 day study.

RESULTS

Triiodothyronine treated rats were hyperthyroid compared to controls, with an elevation in serum T3 levels (3.8+/-0.9 mmol/L vs 1.3+/-0.4 mmol/L, p<0.05). In rats treated with methimazole, hypothyroidism was confirmed by a 7-fold increase in serum TSH compared to controls (1.8+/-0.4 vs 0.24+/-0.04 mmol/L, p<0.01). Portal pressure was significantly higher in the triiodothyronine treated rats compared to controls (12.8+/-1.7 and 9.6+/-0.75 cm H2O, p<0.001). Splenic weights in hyperthyroid rats were significantly higher than in controls (579+/-44 vs 478+/-46 mg, p<0.01). Portal pressure was significantly lower in the methimazole treated group compared to the control group (8.13+/-0.68 vs 9.6+/-0.75 cm H2O, p<0.01) as were splenic weights (400+/-33 vs 478+/-46 mg, p<0.01).

CONCLUSION

These studies demonstrate that disturbed thyroid function exerts significant hemodynamic effects on the portal circulation in normal rats and complements results from previous similar studies in cirrhotic animals.

Hemodynamic effects of hypothyroidism induced by methimazole in normal and portal hypertensive rats

Portal hypertension is accompanied by a hyperdynamic circulatory state that shares some similarities with thyrotoxicosis. This study was conducted in order to investigate the hemodynamic effects of hypothyroidism in a rat model with portal hypertension induced by partial portal vein ligation (PVL). Four groups of 10 rats each were studied: normal control and hypothyroid rats, and PVL control and hypothyroid rats. Hypothyroidism was induced by methimazole 0.04% in drinking water. Hemodynamic measurements were performed using the radioactive microsphere technique. Induction of hypothyroidism was confirmed by elevated TSH levels. In the PVL groups, hypothyroidism ameliorated the hyperdynamic circulation. Portal venous inflow and portal pressure dropped significantly: 7.1 +/- 0.2 vs 4.8 +/- 0.3 ml/min/100 g body wt (P < 0.01) and 13.4 +/- 0.9 vs 10.9 +/- 0.8 mm Hg; (P < 0.01), respectively. In normal rats, hypothyroidism was manifested by a hypodynamic circulatory state. These results demonstrate that hypothyroidism induced by methimazole is followed by amelioration of the hyperdynamic circulation, normalization of portal venous inflow, and reduction of portal pressure.

Pathophysiology and prognosis of oesophageal varices

The fundamental initiating factor in portal hypertension is an increase in resistance to portal venous flow. Portal venous pressure rises as a consequence, and collateral channels open to decompress the portal venous system. A number of secondary haemodynamic phenomena occur in animals and humans with portal hypertension. Systemic vascular resistance and mean arterial blood pressure fall and both cardiac output and splanchnic blood flow increase. Current theories suggest that increased vascular production of nitric oxide may have a principal role in the pathogenesis of these secondary haemodynamic changes. The most common causes of variceal bleeding are cirrhosis, schistosomiasis and extrahepatic portal venous obstruction. Varices develop in 90% of cirrhotic patients if follow-up is long enough. Bleeding from varices occurs in approximately 30% of patients followed up for 2-4 years, with mortality rates of 25% to 50% in those who bled. Prognosis is better in conditions where liver function is preserved, e.g. portal venous obstruction, schistosomiasis, etc.

N omega-nitro-L-arginine administration corrects peripheral vasodilation and systemic capillary hypotension and ameliorates plasma volume expansion and sodium retention in portal hypertensive rats

In portal hypertensive states, peripheral vasodilation leads to sodium retention and plasma volume expansion. N omega-nitro-L-arginine, a specific biosynthesis inhibitor of the vasodilator nitric oxide, has been shown to acutely reverse peripheral vasodilation and the vascular hyporesponsiveness to endogenous and exogenous vasoconstrictors observed in portal hypertensive rats. This study investigated whether N omega-nitro-L-arginine treatment in portal hypertensive rats prevents peripheral vasodilation and therefore ameliorates plasma volume expansion and sodium retention. For 2 days before partial portal vein ligation or sham operation and then continuously for 4 days after the operation, animals received either placebo (0.9% saline) or N omega-nitro-L-arginine (approximately 2 micrograms/kg/min) intravenously through a subcutaneously implanted Alzet osmotic pump (model 2ML1; Alza, Palo Alto, CA). In portal hypertensive rats, N omega-nitro-L-arginine treatment significantly increased mean arterial pressure (placebo vs. N omega-nitro-L-arginine, 123 +/- 4 vs. 150 +/- 2 mm Hg, respectively; p < 0.001) and systemic vascular resistance (3.8 +/- 0.2 vs. 5.6 +/- 0.3 mm Hg/ml/min/100 gm body weight; p < 0.001), associated with a decrease in the cardiac index (33.5 +/- 1.0 vs. 27.0 +/- 1.1 ml/min/100 gm body weight; p < 0.001). N omega-nitro-L-arginine treatment also induced a decrease in plasma volume (4.6 +/- 0.1 vs. 4.1 +/- 0.1 ml/100 gm body weight; p < 0.001) and extracellular sodium space (39.4 +/- 0.7 vs. 37.4 +/- 0.4 ml/100 gm body weight; p < 0.05) without changes in serum sodium.(ABSTRACT TRUNCATED AT 250 WORDS)

Management of gastric varices

Gastric varices (GV) are a common (20%) accompaniment of portal hypertension; they are more often seen in those patients who bleed than in those who do not (27% versus 4%, p < 0.01). They can develop in both segmental and generalized portal hypertension. Depending on their location and relation with oesophageal varices, GVs can be classified as gastrooesophageal varices (GOV) and isolated gastric varices (IGV); each of these can be further subdivided as follows: GOV1 (extension of oesophageal varices along lesser curve) and GOV2 (extension of oesophageal varices towards fundus); and IGV1 (varices in the fundus) and IGV2 (isolated varices anywhere in the stomach). The common presentation of GVs is variceal bleeding and encephalopathy. In comparison with oesophageal varices, GVs bleed significantly less often (64% versus 25%, p < 0.01) but more severely (2.9 +/- 0.3 versus 4.8 +/- 0.6 transfusion units, p < 0.01). Patients with GOV2 and IGV1 bleed more often than patients with other types of GVs. Sclerotherapy for oesophageal varices can significantly influence the natural history of GVs. GOV1, or lesser curve varices, disappear in the majority of cases (59%) after obliteration of oesophageal varices. In those with persisting GOV1, the incidence of bleeding and mortality is high and these patients require gastric variceal sclerotherapy (GVS). During oesophageal variceal sclerotherapy, bleeding can occasionally be induced from GVs. After obliteration of oesophageal varices, recurrence as GVs (secondary GVs) can occur in about 9% of patients. Emergency GVS is quite effective in controlling acute bleeding from GVs, more so than balloon tamponade. Potent sclerosants like tetradecyl sulphate and alcohol and a glue, bucrylate, have been quite effective. Elective GVS can achieve obliteration of GVs in nearly 70% of patients. Rebleeding and ulceration are common complications of GVS; probably related to incomplete obliteration and mucosal injury respectively. Splenectomy is quite effective in treating GVs due to segmental protal hypertension. For GV bleeding due to generalized portal hypertension, a shunt operation is often effective. TIPS procedure appear to be a very promising therapy for GV bleeding. Liver transplantation may be a superior alternative to sclerotherapy and shunt surgery for gastric varices.

Exsanguinating hemorrhage from a caput medusae: cutaneous variceal bleeding

We report the case of a 45-year-old female who presented to the emergency department with massive umbilical hemorrhage from a cutaneous varix. The patient had a long-standing history of alcohol-related liver disease and ascites. Her clinical course was complicated by coagulopathy and hemorrhagic shock, and she ultimately expired. Ectopic or nongastroesophageal bleeding constitutes a significant site of variceal hemorrhage. In this report we review the literature and explore methods of treatment.

Chaos and predicting varix hemorrhage

Despite a wide array of mechanisms implicated in esophagogastric varix hemorrhage, predicting the onset of bleeding or even identifying the dominant factor in its causation has proved elusive. In this article we re-examine variceal pathophysiology and hypothesize that bleeding is rooted in turbulent portal system flow, a phenomenon embodied in the 'new' science of chaos and the principles of non-linear, rhythmic fluid dynamics. Analogous to forecasting the weather, predicting turbulent flow hinges on defining the initial physical conditions, and, like the field theory of quantum physics, depends on probabilities and instabilities rather than direct proportional analysis. Based on the complex regional and systemic hemodynamic forces and local physical properties underlying formation and perpetuation of esophagogastric varices, we propose, as with climatologic events, that a relatively minor or remote physiologic adjustment may set into motion a sequence of destabilizing splanchnic blood flow kinetics that ultimately causes a varix to erupt. In other words, the onset of varix bleeding derives from a sudden, erratic switch from disorganized but stable to disruptive turbulent variceal blood flow, and as a 'chaotic' phenomenon, is likely to remain for the foreseeable future highly unpredictable.