Differential Development of the Chordae Tendineae and Anterior Leaflet of the Bovine Mitral Valve.

There is increasing evidence that some adult mitral valve pathologies may have developmental origins involving errors in cell signaling and protein deposition during valvulogenesis. While early and late gestational stages are well-documented in zebrafish, chicks, and small mammalian models, longitudinal studies in large mammals with a similar gestational period to humans are lacking. Further, the mechanism of chordae tendineae formation and multiplication remains unclear. The current study presents a comprehensive examination of mitral anterior leaflet and chordae tendineae development in a bovine model (a large mammal with the same gestational period as humans). Remarkably distinct from small mammals, bovine development displayed early branched chordae, with increasing attachments only until birth, while the anterior leaflet grew both during gestation and postnatally. Chordae also exhibited accelerated collagen deposition, maturation, and crimp development during gestation. These findings suggest that the bovine anterior leaflet and chordae tendineae possess unique processes of development despite being a continuous collagenous structure and could provide greater insight into human valve development.

Complementary roles of interventional radiology and therapeutic endoscopy in gastroenterology.

Acute upper and lower gastrointestinal bleeding, enteral feeding, cecostomy tubes and luminal strictures are some of the common reasons for gastroenterology service. While surgery was initially considered the main treatment modality, the advent of both therapeutic endoscopy and interventional radiology have resulted in the paradigm shift in the management of these conditions. In this paper, we discuss the patient's work up, indications, and complementary roles of endoscopic and angiographic management in the settings of gastrointestinal bleeding, enteral feeding, cecostomy tube placement and luminal strictures. These conditions often require multidisciplinary approaches involving a team of interventional radiologists, gastroenterologists and surgeons. Further, the authors also aim to describe how the fields of interventional radiology and gastrointestinal endoscopy are overlapping and complementary in the management of these complex conditions.

Pain and efficacy of local anesthetics for central venous access.

PURPOSE: To compare pain during injection and efficacy of analgesia of local anesthetics during central venous line placement. METHODS: Sixty-two patients were studied in a randomized, double-blinded prospective fashion. Patients received 1% lidocaine (L), buffered 1% lidocaine (LB), or 2% chloroprocaine (CP) injected around the internal jugular vein for procedural analgesia for central venous access. Patients reported pain via a standard linear visual analog scale, with 0 representing no pain and 10 being the worst pain imaginable. RESULTS: Overall patient perception of pain was better with CP and L than LB with mean scores of CP 2.4, L 2.6, LB 4.2. Pain with injection mean scores were CP 2.1, L 2.5, LB 3.2. Pain with catheter placement scores were CP 2.5, L 1.7, LB 3.4. Operator assessment of overall pain values were CP 1.9, L 2.2, LB 3.4. LB consistently scored the worst, though compared with CP, this only reached statistical significance in overall patient pain and pain at catheter insertion compared with L. CONCLUSION: Though chloroprocaine scored better than lidocaine in 3 of 4 parameters, this trend did not achieve statistical significance. Adding sodium bicarbonate to lidocaine isn't justified in routine practice, nor is routine replacement of lidocaine with chloroprocaine.

Hemodialysis access success: beyond the operating room.

BACKGROUND: Publication of the Kidney Disease Outcomes Quality Initiative (KDOQI) Guidelines has reinforced an already increased focus within the Veterans Health Administration (VHA) on arteriovenous (AV) hemodialysis (HD) vascular access. Meeting these KDOQI goals has been the responsibility of individual VHA centers. We responded by organizing a dedicated HD AV clinic to provide preoperative evaluation and postoperative follow-up. METHODS: The records of 130 patients referred from January 2004 through June 2006 to our AV HD clinic were retrospectively reviewed. A minimum of 6 months of postoperative follow-up was required. RESULTS: AV fistulae were performed in 71% of the patients, with approximately 45% being Brescia-Cimino fistulae. Importantly, only 38% of AV fistulae matured and were used without secondary intervention. The remaining 62% of AV fistulae each required 2.2 +/- .3 interventions. The final AV fistula use rate was approximately 85%. CONCLUSIONS: To meet these KDOQI guidelines, the VHA should continue to support the concept of dedicated AV HD teams and clinics. This is essential because the majority of our new AV fistulae required secondary intervention for AV fistulae maturation and use. A dedicated HD access team should better be able to assess AV fistula maturation and organize subsequent intervention to promote AV fistulae use.

Complication rate of venous access procedures performed by a radiology practitioner assistant compared with interventional radiology physicians and supervised trainees.

PURPOSE: To compare venous access complication rates associated with procedures performed by radiology practitioner assistants (RPAs) versus interventional radiology (IR) faculty members, IR fellows, and radiology residents. MATERIALS AND METHODS: A retrospective review of venous access procedures in the IR department for 12 consecutive months at a single university hospital was performed. Procedural primary operators included 12 radiology residents, two IR fellows, four IR faculty members, and one board-certified RPA with 2 years of university training. Data examined included immediate and short-term complications separated into major and overall categories. RESULTS: A total of 2093 venous access procedures were performed. The RPA performed 670 procedures (temporary central venous catheter placement, n = 274; peripherally inserted central catheter, n = 67; venous access catheter change, n = 99; venous port placement, n = 126; tunneled central venous catheter placement, n = 39; catheter check, n = 32; and venous explant, n = 43). Similar procedure ratios were noted with faculty members, fellows, and residents. Procedures by the RPA had a major complication rate of 0.29% and an overall complication rate of 0.89%. Four IR faculty members performed 291 procedures, with no major complications and an overall complication rate of 1.71%. Two IR fellows performed 562 procedures, with a major complication rate of 0.35% and an overall complication rate of 1.06%. Twelve residents performed 570 procedures, with a major complication rate of 0.52% (range, 0%-2.46%) and an overall complication rate of 1.39% (range, 0%-3.70%). No significant difference was found among groups (P = .7). CONCLUSION: A properly trained and monitored RPA can safely perform selected venous access procedures with complication rates equal to those of IR faculty members, fellows, and residents.

Paravertebral block: an improved method of pain control in percutaneous transhepatic biliary drainage.

BACKGROUND AND PURPOSE: Percutaneous transhepatic biliary drainage remains a painful procedure in many cases despite the routine use of large amounts of intravenous sedation. We present a feasibility study of thoracic paravertebral blocks in an effort to reduce pain during and following the procedure and reduce requirements for intravenous sedation. METHODS: Ten consecutive patients undergoing biliary drainage procedures received fluoroscopically guided paravertebral blocks and then had supplemental intravenous sedation as required to maintain patient comfort. Levels T8-T9 and T9-T10 on the right were targeted with 10-20 ml of 0.5% bupivacaine. Sedation requirements and pain levels were recorded. RESULTS: Ten biliary drainage procedures in 8 patients were performed for malignancy in 8 cases and for stones in 2. The mean midazolam use was 1.13 mg i.v., and the mean fentanyl requirement was 60.0 microg i.v. in the block patients. Two episodes of hypotension, which responded promptly to volume replacement, may have been related to the block. No serious complications were encountered. The mean pain score when traversing the chest wall, liver capsule, and upon entering the bile ducts was 0.1 on a scale of 0 to 10, with 1 patient reporting a pain level of 1 and 9 reporting 0. The mean peak pain score, encountered when manipulating at the common bile duct level or when addressing stones there, was 5.4 and ranged from 0 to 10. CONCLUSIONS: Thoracic paravertebral block with intravenous sedation supplementation appears to be a feasible method of pain control during biliary interventions.

Popliteal artery disease: diagnosis and treatment.

The popliteal artery is a relatively short vascular segment but is affected by a unique set of pathologic conditions. These conditions, which may be common throughout the arterial system or exclusive to the popliteal artery, include atherosclerosis, popliteal artery aneurysm, arterial embolus, trauma, popliteal artery entrapment syndrome, and cystic adventitial disease. The clinical manifestations, imaging appearances, and treatment options associated with these pathologic conditions differ significantly. Consequently, the radiologist should be familiar with these conditions to direct imaging for accurate diagnosis and treatment and to prevent loss of limb.

Route of hepatocyte delivery affects hepatocyte engraftment in the spleen.

In laboratory animals, intrasplenic hepatocyte transplantation corrects the physiologic abnormalities associated with decompensated liver disease. The clinical experience with hepatocyte transplantation for cirrhosis has been disappointing when compared with laboratory experience. The route of hepatocyte delivery may influence hepatocyte engraftment and function. Outbred pigs were recipients of allogeneic pig hepatocytes. Donor hepatocytes were isolated by collagenase perfusion and labeled using 5(6)-carboxyfluorescein diacetate succinimidyl-ester (CMFSE). Cells were introduced into pig spleens by infusion through the splenic artery or by direct splenic puncture. Direct intrasplenic injection produced engraftment that was far superior to that obtained using splenic artery infusion. Splenic artery infusion produced a gastric erosion and large areas of splenic necrosis secondary to vascular occlusion with hepatocytes, whereas direct splenic injection was associated with clinically insignificant intraabdominal hemorrhage. The route of hepatocyte delivery may influence hepatocyte engraftment and explain the disparity in efficacy of hepatocyte transplantation between the laboratory and clinic.

Isolated hepatocyte transplantation in an infant with a severe urea cycle disorder.

OBJECTIVE: Transplantation of isolated hepatocytes in animal models has been shown to correct inborn errors of metabolism. Based on these studies and our experience with hepatocyte transplantation in a child with Crigler-Najjar syndrome, isolated hepatocyte transplantation was performed to attempt metabolic reconstitution in a male infant with severe ornithine transcarbamylase (OTC) deficiency. METHODS: An infant with an antenatal diagnosis of OTC deficiency was managed intensively to prevent hyperammonemia. Isolated hepatocytes were obtained by collagenase perfusion of donated livers not used for transplantation. Hepatocytes were infused in batches over the first 4 weeks of life via an umbilical venous catheter positioned in the portal vein. Immunosuppression consisted of tacrolimus and corticosteroids. RESULTS: Over 4 billion viable hepatocytes were transplanted during the first 3.5 weeks of life. A period of metabolic stability was achieved between days 20 and 31 during which normal protein intake was tolerated while phenylbutyrate was weaned. During this time, plasma ammonia and glutamine remained within normal limits. Hyperammonemia reappeared abruptly on day 31 of life. Protein tolerance diminished to baseline; metabolic stability was subsequently reattained only following successful liver transplantation at 6 months of age. CONCLUSIONS: Isolated hepatocyte transplantation appeared to result in temporary relief of hyperammonemia and protein intolerance attributable to OTC deficiency. The metabolic stability achieved was lost after 11 days presumably because of rejection of the transplanted cells because of insufficient immunosuppression. Future attempts at isolated hepatocyte transplantation for inborn errors of metabolism in humans should include adequate immunosuppression and a liver biopsy as a means of proving hepatocyte engraftment and function.

Microbubble-augmented ultrasound declotting of thrombosed arteriovenous dialysis grafts in dogs.

PURPOSE: Transcutaneous low-frequency ultrasound (LFUS) can effectively lyse clots in the presence of microbubbles. This study was designed to test the commercially available human albumin microspheres injectable suspension octafluoropropane formulation, Optison, to establish efficacy and assess US parameters of intensity and wave modes in a canine model of a thrombosed arteriovenous (dialysis) graft. MATERIALS AND METHODS: Arteriovenous grafts in five dogs were cannulated, temporarily ligated, and thrombosed. Different declotting techniques were randomized to treat nine groups. Control groups involved direct saline (4.5 mL) clot injection in 0.5-1.0-mL increments. One group underwent peripheral intravenous microbubble injection (13.5 mL). Six groups underwent direct incremental clot injection of 4.5 mL of microspheres with LFUS for 30 minutes in 3-5-minute increments with use of various intensity settings in continuous-wave and pulsed-wave (PW) modes. At each increment, angiography was used to grade flow, declotting, and overall success. RESULTS: One hundred four procedures showed success in all 24 high-intensity PW modes (1.2-2.0 W/cm(2)); only one of 20 control experiments was successful (P <.0001). Medium-intensity modes yielded intermediate success rates. Lowest-intensity direct-injection groups and intravenous and control groups ranked lower. Results at 30 minutes were better than at 15 minutes (P <.0001). CONCLUSIONS: LFUS with direct injection of microbubbles is effective in lysing moderate-sized clots and recanalizing thrombosed arteriovenous grafts. It best succeeds at the higher range of intensity settings tested in PW mode. Further development is justified.