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American Journal of Physiology. Heart... Feb 2016Pulmonary hyperinflation is used by competitive breath-hold divers and is accomplished by glossopharyngeal insufflation (GPI), which is known to compress the heart and...
Pulmonary hyperinflation is used by competitive breath-hold divers and is accomplished by glossopharyngeal insufflation (GPI), which is known to compress the heart and pulmonary vessels, increasing sympathetic activity and lowering cardiac output (CO) without known consequence for organ perfusion. Myocardial, pulmonary, skeletal muscle, kidney, and liver perfusion were evaluated by magnetic resonance imaging in 10 elite breath-hold divers at rest and during moderate GPI. Cardiac chamber volumes, stroke volume, and thus CO were determined from cardiac short-axis cine images. Organ volumes were assessed from gradient echo sequences, and organ perfusion was evaluated from first-pass images after gadolinium injection. During GPI, lung volume increased by 5.2 ± 1.5 liters (mean ± SD; P < 0.001), while spleen and liver volume decreased by 46 ± 39 and 210 ± 160 ml, respectively (P < 0.05), and inferior caval vein diameter by 4 ± 3 mm (P < 0.05). Heart rate tended to increase (67 ± 10 to 86 ± 20 beats/min; P = 0.052) as right and left ventricular volumes were reduced (P < 0.05). Stroke volume (107 ± 21 to 53 ± 15 ml) and CO (7.2 ± 1.6 to 4.2 ± 0.8 l/min) decreased as assessed after 1 min of GPI (P < 0.01). Left ventricular myocardial perfusion maximum upslope and its perfusion index decreased by 1.52 ± 0.15 s(-1) (P < 0.001) and 0.02 ± 0.01 s(-1) (P < 0.05), respectively, without transmural differences. Pulmonary tissue, spleen, kidney, and pectoral-muscle perfusion also decreased (P < 0.05), and yet liver perfusion was maintained. Thus, during pulmonary hyperinflation by GPI, CO and organ perfusion, including the myocardium, as well as perfusion of skeletal muscles, are reduced, and yet perfusion of the liver is maintained. Liver perfusion seems to be prioritized when CO decreases during GPI.
Topics: Adult; Breath Holding; Cardiac Output; Cardiac Volume; Coronary Circulation; Diving; Female; Humans; Liver Circulation; Magnetic Resonance Imaging; Magnetic Resonance Imaging, Cine; Male; Muscle, Skeletal; Pulmonary Circulation; Regional Blood Flow; Renal Circulation; Stroke Volume
PubMed: 26589331
DOI: 10.1152/ajpheart.00739.2015 -
Journal of Hepatology Apr 2015Among the common complication of cirrhosis portal hypertension witnessed a major improvement of prognosis during the past decades. Principally due to the introduction of... (Review)
Review
Among the common complication of cirrhosis portal hypertension witnessed a major improvement of prognosis during the past decades. Principally due to the introduction of rational treatments based on new pathophysiological paradigms (concepts of thought) developed in the 1980s. The best example being the use of non-selective beta-blockers and of vasopressin analogs, somatostatin, and its analogs. Further refinement in the knowledge of the molecular mechanisms involved in the regulation of both the splanchnic and hepatic circulation has led to the emergence of new treatments, which are based on evidence that show not only structural but also vasoactive components increase the hepatic vascular resistance, as well as of angiogenesis. This knowledge and future improvements will most likely result in more effective treatment of portal hypertension and effective prevention of its complications in early stages.
Topics: Hepatic Artery; Humans; Hypertension, Portal; Liver Circulation; Neovascularization, Physiologic; Splanchnic Circulation
PubMed: 25920081
DOI: 10.1016/j.jhep.2015.01.003 -
European Radiology Jun 2015To investigate the feasibility of selective arterial and portal venous liver perfusion imaging with spin labelling (SL) MRI, allowing separate labelling of each blood...
PURPOSE
To investigate the feasibility of selective arterial and portal venous liver perfusion imaging with spin labelling (SL) MRI, allowing separate labelling of each blood supply.
METHODS
The portal venous perfusion was assessed with a pulsed EPISTAR technique and the arterial perfusion with a pseudo-continuous sequence. To explore precision and reproducibility, portal venous and arterial perfusion were separately quantified in 12 healthy volunteers pre- and postprandially (before and after meal intake). In a subgroup of 6 volunteers, the accuracy of the absolute portal perfusion and its relative postprandial change were compared with MRI flow measurements of the portal vein.
RESULTS
The portal venous perfusion significantly increased from 63 ± 22 ml/100g/min preprandially to 132 ± 42 ml/100g/min postprandially. The arterial perfusion was lower with 35 ± 22 preprandially and 22 ± 30 ml/100g/min postprandially. The pre- and postprandial portal perfusion using SL correlated well with flow-based perfusion (r(2) = 0.71). Moreover, postprandial perfusion change correlated well between SL- and flow-based quantification (r(2) = 0.77). The SL results are in range with literature values.
CONCLUSION
Selective spin labelling MRI of the portal venous and arterial blood supply successfully quantified liver perfusion. This non-invasive technique provides specific arterial and portal venous perfusion imaging and could benefit clinical settings where contrast agents are contraindicated.
KEY POINTS
• Perfusion imaging of the liver by Spin Labelling MRI is feasible • Selective Spin Labelling MRI assessed portal venous and arterial liver perfusion separately • Spin Labelling based portal venous liver perfusion showed significant postprandial increase • Spin Labelling based portal perfusion correlated well with phase-contrast based portal perfusion • This non-invasive technique could benefit settings where contrast agents are contraindicated.
Topics: Adult; Feasibility Studies; Female; Humans; Liver; Liver Circulation; Magnetic Resonance Imaging; Male; Mesenteric Artery, Superior; Portal Vein; Postprandial Period; Reference Values; Reproducibility of Results; Spin Labels
PubMed: 25796581
DOI: 10.1007/s00330-014-3524-z -
Journal of Gastrointestinal and Liver... Sep 2006The liver has a unique dual blood supply from the hepatic artery (25%) and the portal vein (75%). Helical computer tomography (CT) and also magnetic resonance imaging... (Review)
Review
The liver has a unique dual blood supply from the hepatic artery (25%) and the portal vein (75%). Helical computer tomography (CT) and also magnetic resonance imaging (MRI) are suitable techniques for hepatic imaging. Helical CT and MR angiography allow single breath-hold scanning without motion artifacts. This article illustrates helical CT and MRI findings of different types of hepatic perfusion disorders. Because of rapid image acquisition, three-phase (hepatic arterial phase, portal venous phase and parenchymal phase) CT or MR-angiography evaluation of the hepatic parenchyma is possible, improving perfusion disorders evaluation, tumors detection and characterization in a single study. We classified hepatic perfusion abnormalities in: portal disorders, arterial disorders, hepatic veins abnormalities, intrahepatic vascular communication, hepatic lesions and perfusion disorders and other causes. Differential diagnosis and pitfalls of these entities must be known for a correct diagnosis of focal hepatic lesions.
Topics: Humans; Liver Circulation; Liver Diseases; Magnetic Resonance Angiography; Portal System; Tomography, Spiral Computed; Vascular Diseases
PubMed: 17013453
DOI: No ID Found -
Minerva Anestesiologica Dec 2015Arginine-vasopressin (AVP) is an important hormone in the regulation of plasma osmolality and blood volume/pressure. In clinical practice it is frequently used in the... (Review)
Review
Arginine-vasopressin (AVP) is an important hormone in the regulation of plasma osmolality and blood volume/pressure. In clinical practice it is frequently used in the treatment of septic shock and decompensated cirrhosis. In this review the physiology of AVP and its analogues is presented. In addition the use of AVP in cirrhosis and sepsis is reviewed.
Topics: Arginine Vasopressin; Humans; Liver Circulation; Liver Cirrhosis; Sepsis; Shock, Septic; Vasoconstrictor Agents; Vasopressins
PubMed: 25384691
DOI: No ID Found -
Annals of Surgery Jun 1964
Topics: Aneurysm; Angiography; Arteries; Arteriosclerosis; Arteriovenous Fistula; Geriatrics; Hepatic Artery; Humans; Hypertension; Hypertension, Portal; Liver Circulation; Liver Diseases; Liver Neoplasms; Stomach Neoplasms; Vascular Diseases; Vascular Surgical Procedures; Wounds and Injuries
PubMed: 14170291
DOI: 10.1097/00000658-196406000-00007 -
World Journal of Gastroenterology May 2006In this article, we have reviewed the hepatic perfusion disorder (HPD), etiopathogenesis of HPD and corresponding diseases. Review of the literature was based on... (Review)
Review
In this article, we have reviewed the hepatic perfusion disorder (HPD), etiopathogenesis of HPD and corresponding diseases. Review of the literature was based on computer searches (PubMed, Index Medicus) and personal experiences. We considered HPD reflects perfusion differences due to redistribution of arterial blood flow among segments, subsegments and lobes of the liver. The plain CT scan findings of HPD manifests as triangular or wedge-shaped areas of low attenuation. On contrast-enhanced CT scan, HPD manifests multiple (or single) transient wedge-shaped, rotundloid or irregular appearance, homogeneous hyperattenuation (in less cases, hypoattenuation) during the hepatic arterial phase (HAP) and isoattenuated or slightly hyperattenuated areas during the portal arterial phase. Dynamic enhanced magnetic resonance (MR) features are similar to enhanced CT scan. Angiographic findings include non-opacification of portal vein on portograms or wedge-shaped segmental staining in arterial and parenchymal phases on hepatic angiograms. The causes of HPD are arterioportal shunts (APS), intrahepatic vascular compressions and portal vein occlusion, steal phenomenon by hypervascular tumors, vascular variations and any other unknown reasons. It is very important for radiologists to be familiar with the various appearances of HPD to avoid false-positive diagnosis of pseudolesions and not to overestimate the extent of the disease.
Topics: Diagnosis, Differential; Hemodynamics; Hepatic Artery; Hepatic Veins; Humans; Liver; Liver Circulation; Liver Diseases; Liver Neoplasms; Magnetic Resonance Imaging; Pulsatile Flow; Regional Blood Flow; Telangiectasia, Hereditary Hemorrhagic; Tomography, X-Ray Computed; Vascular Diseases
PubMed: 16718850
DOI: 10.3748/wjg.v12.i20.3265 -
Annals of the Royal College of Surgeons... Nov 2002There has been a significant increase in the number of hepatic resections performed. The aim of this review was to assess available techniques for liver resection and... (Review)
Review
BACKGROUND
There has been a significant increase in the number of hepatic resections performed. The aim of this review was to assess available techniques for liver resection and their application.
METHODS
A literature review was performed based on a Medline search to identify articles on liver resection. Keywords included liver resection, liver neoplasm, cancer, colorectal metastases and hepatocellular carcinoma.
RESULTS
Improved understanding of the segmental anatomy of the liver has resulted in the evolution of liver resection. The development of new approaches to the biliovascular tree, combined with clamping to produce ischaemic demarcation, has been important in demonstrating segmental boundaries for resection. The combination of methods of vascular control such as the Pringle manoeuvre and techniques of parenchymal resection such as ultrasonic dissection allows hepatic resection with minimal blood loss and morbidity.
CONCLUSIONS
Application of refined techniques for liver resection by specialised units allows liver resection to be performed on both normal and cirrhotic livers with low morbidity and mortality.
Topics: Blood Loss, Surgical; Constriction; Disease-Free Survival; Hepatectomy; Humans; Liver Circulation; Liver Cirrhosis; Liver Neoplasms
PubMed: 12484574
DOI: 10.1308/003588402760978148 -
World Journal of Gastroenterology May 2015Severe complications of liver cirrhosis are mostly related to portal hypertension. At the base of the pathogenesis of portal hypertension is the increase in hepatic... (Review)
Review
Severe complications of liver cirrhosis are mostly related to portal hypertension. At the base of the pathogenesis of portal hypertension is the increase in hepatic vascular resistance to portal blood flow with subsequent development of hyperdynamic circulation, which, despite of the formation of collateral circulation, promotes progression of portal hypertension. An important role in its pathogenesis is played by the rearrangement of vascular bed and angiogenesis. As a result, strategic directions of the therapy of portal hypertension under liver cirrhosis include selectively decreasing hepatic vascular resistance with preserving or increasing portal blood flow, and correcting hyperdynamic circulation and pathological angiogenesis, while striving to reduce the hepatic venous pressure gradient to less than 12 mmHg or 20% of the baseline. Over the last years, substantial progress in understanding the pathophysiological mechanisms of hemodynamic disorders under liver cirrhosis has resulted in the development of new drugs for their correction. Although the majority of them have so far been investigated only in animal experiments, as well as at the molecular and cellular level, it might be expected that the introduction of the new methods in clinical practice will increase the efficacy of the conservative approach to the prophylaxis and treatment of portal hypertension complications. The purpose of the review is to describe the known methods of portal hypertension pharmacotherapy and discuss the drugs that may affect the basic pathogenetic mechanisms of its development.
Topics: Animals; Antihypertensive Agents; Humans; Hypertension, Portal; Liver Circulation; Liver Cirrhosis; Portal Pressure; Risk Factors; Treatment Outcome
PubMed: 26034348
DOI: 10.3748/wjg.v21.i20.6117 -
American Journal of Physiology.... Feb 2008A look through the literature on liver sinusoidal endothelial cells (LSECs) reveals that there are several conflicts among different authors of what this cell type is... (Review)
Review
A look through the literature on liver sinusoidal endothelial cells (LSECs) reveals that there are several conflicts among different authors of what this cell type is and does. Major controversies that will be highlighted in this review include aspects of the physiological role, the characterization, and the protocols of isolation and cultivation of these cells. Many of these conflicts may be ascribed to the fact that the cell was only recently established as a distinct cell type and that researchers from different disciplines tend to define their structure and function differently. This field is in need of a common platform to obtain a sound communication and a unified understanding of how to interpret novel research results. The aim of this review is to encourage scientists not to ignore the fact that there are, indeed, different opinions in the literature on LSECs. We also hope that this review will point out to the reader that some issues that may seem well established regarding our knowledge about the LSECs, in reality, are still unresolved and, indeed, controversial.
Topics: Animals; Biomarkers; Cell Separation; Cells, Cultured; Endothelial Cells; Hepatocytes; Humans; Liver; Liver Circulation
PubMed: 18063708
DOI: 10.1152/ajpgi.00167.2007