ABSTRACT
The electrode-tissue interface is that area lying between the cathode of a low-voltage implantable pacemaker or cardioverter-defibrillator (ICD) lead and the endocardium or epi-myocardium of the cardiac chamber being paced. The electrical stimulus that is delivered to this interface is responsible for myocyte depolarization with consequent cardiac contraction. The process by which this occurs is reasonably well understood and any explanation requires a basic understanding of the physics and cellular electrophysiology of pacing. The effective and efficient delivery of electrical energy to the myocardium via the lead is dependent on many factors to be discussed in this review. However, despite numerous evolutionary changes occurring in the cathode's material, design, and surface configuration, it was not until the incorporation of steroid-elution to the electrode-tissue interface that reliable and significantly low stimulation threshold cardiac pacing became possible.
Subject(s)
Adrenal Cortex Hormones/administration & dosage , Defibrillators, Implantable , Electrodes, Implanted , Pacemaker, Artificial , Electric Power Supplies , Endocardium/cytology , Equipment Design , Humans , Myocardium/cytology , Surface PropertiesABSTRACT
Acute liver failure (ALF) is a clinical syndrome associated with significant morbidity and mortality with a highly unpredictable outcome. We retrospectively analyzed 71 ALF patients (53 males; mean age = 27.5 ± 15.6 years) that underwent transjugular liver biopsy (TJLB) at our institution. The aims of this study are (i) to report our experience with TJLB in these patients, and (ii) to examine the role of liver histology in predicting their outcome. We also compared the histopathological findings between TJLB and explanted liver specimens in 31 patients who underwent liver transplantation (LT). Biopsy specimens were satisfactory for histopathological analyses in 69 (97.1%) patients, confirmed the clinical diagnosis in 56 (81.2%) patients, and altered the diagnosis in 13 (18.8%) patients. Minor complications were encountered in four (5.6%) patients. Percentage of hepatocyte necrosis was the only histological parameter that has significant discriminatory prognostic value, with no survivors having >75% necrosis without LT. In conclusions, TJLB is a safe technique for obtaining liver tissue in both adult and pediatric patients with ALF. Histological characteristics, mainly etiological diagnosis and degree of hepatocyte necrosis may assist in clinical decision-making for need of LT in these patients.
Subject(s)
Biopsy, Needle/methods , Liver Failure, Acute/pathology , Liver/pathology , Adolescent , Adult , Child , Child, Preschool , Female , Hepatocytes/pathology , Humans , Infant , Liver/surgery , Liver Failure, Acute/etiology , Liver Failure, Acute/mortality , Liver Failure, Acute/surgery , Liver Transplantation , Male , Middle Aged , Necrosis , Prognosis , Retrospective Studies , Severity of Illness Index , Young AdultABSTRACT
Hepatic artery thrombosis (HAT) is the most frequent vascular complication following orthotopic liver transplantation. Urgent retransplantation has been considered as the mainstay therapy. Surgical revascularization is an effective alternative in asymptomatic patients. Endovascular therapies including intra-arterial thrombolysis, percutaneous transluminal angioplasty (PTA), and stent placement have shown encouraging results in recent years; however, their use remains controversial because of potential risk of hemorrhage. Until June 2009, 69 cases were published in 16 reports describing therapeutic potential of endovascular modalities. Interventions were performed as early as within 4 h to as late as 120 days in patients ranging from 4 months to 64 years of age. Majority of published reports suggested the use of urokinase. Thrombolysis was successful in 47 out of 69 (68%) patients. Bleeding was the most common complication including fatal intra-abdominal hemorrhage in three patients. Twenty-nine out of 47 (62%) patients underwent further intervention in the form of PTA, stenting, or both. The follow-up patency ranged from 1 month to 26 months. In conclusion, whenever possible, efforts should be made to rescue the liver grafts through urgent revascularization (surgical and/or endovascular) depending on patient's condition and interventional expertise at the transplant center; reserving the option of retransplantation for failure, complications, and cases with severe clinical symptoms or allograft dysfunction.
Subject(s)
Hepatic Artery , Liver Transplantation/adverse effects , Thrombosis/etiology , Thrombosis/therapy , Angioplasty, Balloon , Hemorrhage/etiology , Humans , Stents , Thrombolytic Therapy/adverse effects , Treatment Outcome , Urokinase-Type Plasminogen Activator/therapeutic useABSTRACT
Hepatic artery thrombosis remains one of the major causes of graft failure and mortality in liver transplant recipients. Urgent re-transplantation has been considered as mainstay therapy; however, even with re-transplantation mortality of more than 50% has been reported by many series. Early detection on Doppler ultrasonography and subsequent revascularization in asymptomatic patients can avoid graft loss. Endovascular therapy including intra-arterial thrombolysis, percutaneous transluminal angioplasty, and stent placement have shown encouraging results in recent years; nevertheless, their use remains controversial due to potential risk of bleeding. We present a case of early hepatic artery thrombosis following liver transplantation treated successfully with continuous transcatheter intra-arterial thrombolysis using tissue plasminogen activator (t-PA).
