First report on extended distance between tumor lesion and adjacent organs at risk using interventionally applied balloon catheters: a simple procedure to optimize clinical target volume covering effective isodose in interstitial high-dose-rate brachytherapy of liver malignomas.

PURPOSE: Organs at risk (OARs), which are very close to a clinical target volume (CTV), can compromise effective tumor irradiation. The present study investigated the feasibility and safety of a novel approach, in particular, the extent of the dosimetric effect of distancing CTV from adjacent OARs by means of interventionally applied balloon catheters. MATERIAL AND METHODS: Patients with peripheral hepatic malignancies, in whom the critical proximity of an OAR to the CTV in the assessment by contrast-enhanced magnetic resonance imaging (MRI) scans and the preplanning process were included. Additionally, patients underwent placement of an interventional balloon catheter during computed tomography (CT)-guided application of interstitial brachytherapy (iBT) catheters inserted into the tissue between hepatic capsule and adjacent OAR. The virtual position of an OAR without balloon catheter was anticipated and contoured in addition to contouring of CTV and OAR. The calculated dose values for CTV as well as 1 cc of the relevant OAR (D1cc) with and without balloon were recorded. The D1cc of the realized irradiation plan was statistically compared to the D1cc of the virtually contoured OARs. RESULTS: In 31 cases, at least one balloon catheter was administered. The mean D1cc of the OAR in the group with balloon(s) was 12.6 Gy compared with 16 Gy in the virtual cohort without the device, therefore significantly lower (p < 0.001). Overall, there were no acute complications. Severe (> 2 CTCAEv4.03) late complications observed in 3/31 (9.6%) patients during follow-up period after brachytherapy were most certainly not due to the balloon application. Side effects were probably associated with pre-existing serious diseases and potentially additional local late effects of the irradiation in general rather than with the balloon catheters. CONCLUSIONS: The distancing of the adjacent OARs allows a higher D100 value of CTV, therefore allowing for more efficient local control.

Percutaneous caval stent valve implantation: investigation of an interventional approach for treatment of tricuspid regurgitation.

AIMS: Severe tricuspid regurgitation (TR) reduces cardiac output (CO) and increases central venous pressure leading to secondary organ dysfunction. To date, the open surgical approach is the only option to treat TR. Herein, we report our experience of treatment by percutaneous implantation of valved stents in the inferior vena cava (IVC) and superior vena cava (SVC) to substitute tricuspid valve function in a model of acute insufficiency. METHODS AND RESULTS: Acute TR grades III-IV was created in 13 sheep (54-75 kg) via papillary muscle and chordae avulsion using a 0.07 inch wire blade. Successful creation of TR was confirmed using angiography and by a prominent ventricular wave in central venous pressure recording. Two self-expanding nitinol stents containing a porcine pulmonary valve were then implanted in the IVC and SVC in a transcatheter approach. Implantation was performed through the right jugular vein by means of a 21 F catheter and guided by fluoroscopy. Haemodynamics were continuously monitored and valve function was verified by angiography and epicardial echocardiography. After successful implantation and proof of concept in the acute study (acute group, n = 9), chronic studies were (n = 4, 4 weeks follow-up) performed. Tricuspid regurgitation grades III-IV was successfully created in all animals and resulted in a significant reduction of CO. A ventricular wave in the IVC of 16.2 +/- 2.33 mmHg (acute group) and 14.9 +/- 1.71 mmHg (chronic group) confirmed the presence of severe TR. After deployment of the IVC and the SVC valve, the ventricular wave in the IVC significantly decreased to 13.9 +/- 2.97 mmHg (acute group) and 12.7 +/- 1.15 (chronic group), whereas CO significantly increased to 4.20 +/- 0.84 L/min (acute group) and 5.4 +/- 0.67 L/min (chronic group). At autopsy, correct device position was verified in all successfully implanted animals, no macroscopic damage resulting from the implantation procedure was observed. CONCLUSION: In high-grade tricuspid insufficiency, percutaneous implantation of valved stents in the central venous position reduces venous regurgitation and improves haemodynamics in the animal experiment. Implantation of one or two valves in central venous position is technically feasible. Functional replacement of the insufficient tricuspid valve leads to an increase in CO. This technique expands the potential therapeutic options for patients with relevant tricuspid valve regurgitation having a high risk for open heart surgery.