Jan H. Peregrin

Percutaneous transcatheter aortic disc valve prosthesis implantation: A feasibility study

AbstractPurpose: Over the past 30 years there have been experimental efforts at catheter-based management of aortic valve regurgitation with the idea of extending treatment to nonsurgical candidates. A new catheter-based aortic valve design is described. Methods: The new catheter-delivered valve consists of a stent-based valve cage with locking mechanism and a prosthetic flexible tilting valve disc. The valve cage is delivered first followed by deployment and locking of the disc. In acute experiments, valve implantation was done in four dogs. Results: Valve implantation was successful in all four animals. The implanted valve functioned well for the duration of the experiments (up to 3 hr). Conclusion: The study showed the implantation feasibility and short-term function of the tested catheter-based aortic disc valve. Further experimental studies are warranted.

Magnetic resonance imaging of pancreatic islets transplanted into the liver in humans.

BACKGROUND In vitro labeling of pancreatic islets by iron nanoparticles enables their detection as hypoitnense spots on serial magnetic resonance (MR) images. We report the first results of a pilot trial aiming to test the feasibility and safety of this technique in humans. METHODS Islets were labeled in culture with 5 μL/mL ferucarbotran for 6 to 48 hr and transplanted into the portal vein (12 infusions) in 8 C-peptide negative recipients. The liver area was examined the next day and 1, 4, and 24 weeks posttransplant using a 3T MR scanner. RESULTS In all recipients, significant C-peptide levels and near-normal HbA1c values were achieved with 50% to 80% insulin dose reduction. No side effects related to the labeling procedure were documented. Typically, a significant islet spot number decrease (on average 60%) was detected at week 1 with subsequent only slight decrease for up to 24 weeks. In two subjects with labeling period of less than 6 and 10 hr, only few islet spots were detected corresponding to poor islet visualization in phantoms labeled for the same period of time. CONCLUSION Pancreatic islets (PI) visualization was safe and successful in all recipients but was less efficient if labeling period was less than 16 hr. Significant decrease of islet spots occurred at week 1, suggesting early islet destruction or impaired engraftment. Afterward, the islet spot numbers remained stable for up to 24 weeks. Data show that MR detection of ferucarbotran-labeled islets enables their long-term noninvasive visualization and correlates with sustained C-peptide production.

Self-Expandable Stent Placement in Infrapopliteal Arteries After Unsuccessful Angioplasty Failure: One-Year Follow-up

The purpose of this prospective study was to evaluate whether stent placement in infrapopliteal arteries is helpful in failed percutaneous transluminal angioplasty (PTA). Infrapopliteal PTA was performed in 70 arteries of 66 patients with chronic critical lower limb ischemia. The group comprised 55 males and 11 females, with an average age of 63.4 (range, 42–82) years. Diabetes mellitus was present in 92.4% of patients. Only the palpable anterior tibial and posterior tibial arteries were evaluated. Stents (Xpert stent; Abbot Vascular, Redwood City, CA, USA) were placed in 16 arteries where PTA was not successful (the failure was defined as residual stenosis >30% after PTA). In 54 arteries simple PTA was performed and was technically successful. Twenty-four nondilated arteries with no significant stenosis served as a comparison group. The 12-month patency rate was evaluated according to a combination of palpation and Doppler ultrasound. In all cases stent placement restored the flow in the artery immediately after unsuccessful PTA. Twelve-month follow-up showed a patency rate of 82% in the PTA group, 78% in the stent group, and 69% in the comparison group. We conclude that stent placement in the case of unsuccessful infrapopliteal PTA changed technical failure to success and restored flow in the dilated artery. At 12-month follow-up the patency rate of infrapopliteal arteries stented for PTA failure did not differ significantly either from nonstented arteries with an optimal PTA result or from a comparison group of nonintervened arteries.

New occlusive agent for therapeutic embolization tested in dogs

A new occlusive agent, Vilan 500, was used to embolize the arterial bed of the kidney in 12 dogs. This polyvinyl acetate, alcohol-soluable agent becomes gelantinous on contact with an aqueous environment and its low viscosity makes this material well suited for application through small-caliber catheters. Complete arterial occlusion of the embolized kidneys was observed in all animals. On histologic examination of tissue 4–6 weeks after the procedure, changes were seen such as shrinkage through fibrosis, diffuse necrosis and atrophic parenchyma. No signs of recanalization of the embolized artery or functional collateral circulation were noted in any dog.

Total recovery of left ventricular function after acute myocardial infarction: comprehensive therapy with streptokinase, N-acetylcysteine and percutaneous transluminal coronary angioplasty

In this report we describe our first use of N-acetylcysteine in a patient with his first acute myocardial infarction in an effort to reduce the infarct size and to protect left ventricular function by pharmacological and mechanical therapy (thrombolysis and percutaneous transluminal coronary angioplasty). This comprehensive therapy caused normalization of previously depressed left ventricular systolic function.

Percutaneous balloon occlusion of surgical arteriovenous fistulae following venous thrombectomy

We describe a percutaneous method of balloon occlusion of surgically created femoral arteriovenous fistulae (AVF) after thrombectomy for acute iliofemoral venous thrombosis. The technique was successful in permanent obliteration of the AVF in 25 of 27 patients. Complications were few, minor, and limited to the developmental period of the procedure, No patient required surgical intervention. The procedure provides an opportunity to angiographically evaluate the results of previous thrombectomy

Percutaneous Transluminal Angioplasty of Hepatic Artery Stenosis in Patients After Orthotopic Liver Transplantation: Mid-term Results

PURPOSE This study was designed to present our experience with percutaneous treatment of hepatic artery stenosis in orthotopic liver transplant patients and to evaluate the efficacy, technical outcomes, and mid-term clinical results of the procedure. METHODS Twenty-two percutaneous transluminal angioplasties (PTAs) were performed in 19 liver transplant recipients at our institution between 1998 and 2010. Stents were placed into the hepatic/celiac artery in 16 PTAs, but balloon dilatation alone was performed in 6 because of the anatomical condition of the vessel. PTA/stenting was indicated in 17 patients because of elevated liver enzymes; 2 patients were asymptomatic. The objective of treating stenosis was prevention of long-term complications, including thrombosis. RESULTS Technical success was achieved in all patients. There was only one complication: dissection of the treated artery without any subsequent adverse effects. In all patients, elevated liver enzyme levels improved after treatment. No restenosis was observed in any patient during a mean follow-up of 2.6 years (1 month to 5.5 years). CONCLUSIONS Percutaneous angioplasty/stent placement is a safe method for the treatment of hepatic artery stenosis after orthotopic liver transplantation, with a high technical success rate and promising mid-term results.

Percutaneous Transcatheter One-Step Mechanical Aortic Disc Valve Prosthesis Implantation: A Preliminary Feasibility Study in Swine

PurposeTo evaluate the feasibility of one-step implantation of a new type of stent-based mechanical aortic disc valve prosthesis (MADVP) above and across the native aortic valve and its short-term function in swine with both functional and dysfunctional native valves.MethodsThe MADVP consisted of a folding disc valve made of silicone elastomer attached to either a nitinol Z-stent (Z model) or a nitinol cross-braided stent (SX model). Implantation of 10 MADVPs (6 Z and 4 SX models) was attempted in 10 swine: 4 (2 Z and 2 SX models) with a functional native valve and 6 (4 Z and 2 SX models) with aortic regurgitation induced either by intentional valve injury or by MADVP placement across the native valve. MADVP function was observed for up to 3 hr after implantation.ResultsMADVP implantation was successful in 9 swine. One animal died of induced massive regurgitation prior to implantation. Four MADVPs implanted above functioning native valves exhibited good function. In 5 swine with regurgitation, MADVP implantation corrected the induced native valve dysfunction and the device’s continuous good function was observed in 4 animals. One MADVP (SX model) placed across native valve gradually migrated into the left ventricle.ConclusionThe tested MADVP can be implanted above and across the native valve in a one-step procedure and can replace the function of the regurgitating native valve. Further technical development and testing are warranted, preferably with a manufactured MADVP.

N-Acetylcysteine Attenuates Iodine Contrast Agent-Induced Nephropathy in 5/6-Nephrectomized Rats

Aims: In the present study we tested the efficacy of N-acetylcysteine (NAC) to minimize nephrotoxic effects of iodine contrast agents in intact rats as well as in 5/6-nephrectomized (5/6-Nx) rats. Methods: Rats were allocated to a group of intact rats (n = 42) and a group of 5/6-Nx rats (n = 42). After 1 month of recovery from surgery, 5/6-Nx rats and intact (sham-operated) animals received either 6 ml/kg body weight (b.w.) meglumine ioxithalamate (Telebrix 350) or 6 ml/kg b.w. iohexol (Omnipaque 350) intravenously with or without pretreatment with 100 mg/kg b.w. NAC. Plasma and urinary concentrations of creatinine, sodium and protein in 24-hour urine collections were determined prior to and on days 1, 3 and 7 after drug administration. Results: In intact animals, contrast agents caused no significant changes in kidney function throughout the duration of the experiment. In contrast, significant increases in plasma creatinine levels and decreases in creatinine clearance were induced by both contrast agents in 5/6-Nx rats. These changes were significantly attenuated by NAC pretreatment. Conclusion: The results of the present study demonstrate that iodine contrast agent-induced nephropathy in 5/6-Nx rats is significantly attenuated by intravenous pretreatment with NAC.

Long-term control of hypertension and the predictive value of peripheral plasma renin activity after ablation of end stage kidneys with a new embolic agent

Embolization of end-stage kidneys using our own embolizing agent Vilanol (partially hydrolyzed polyvinyl acetate) was performed in 10 patients with hypertension refractory to conservative therapy. Native kidneys were embolized in 7 patients with chronic renal failure, nonfunctioning renal transplants in 2 patients, and a shrunken kidney in 1 patient. Five of the 10 patients had high (9.96–18.2 ng/ml/h) peripheral renin (PR) levels. The embolization was technically successful in 4 of these 5 patients and was immediately followed by a marked decrease in PR, and simultaneous improvement in blood pressure (BP). The other 5 patients had very low PR levels (0.07–0.65 ng/ml/h), and a reduction in BP was observed in 4 after embolization. One patient died following embolization from cardiac arrest due to hyperkalemia. Six patients (3 in each group) have been on follow-up for 2–5 years with sustained decrease in BP. We conclude that the new agent is effective for renal ablation and control of refractory hypertension.