Percutaneous pulmonary valve placement in a 10-month-old patient using a hand crafted stent-mounted porcine valve

Eighteen-month outcome of pulmonary valve stent implantation by direct right ventricle puncture: an animal study

OBJECTIVE

The purpose of this study was to investigate the feasibility and safety of pulmonary valve implantation via direct right ventricle puncture.

METHODS

A standard thoracotomy and direct right ventricle puncture were performed in 8 healthy sheep to implant the pulmonary valve stents. Animals were followed up for 18 months.

RESULTS

Three sheep died within the first 4 months after stent placement. The remaining 5 animals survived. After 18 months, examinations by color echocardiography, 64-slice computed tomography scan, and cardiac catheter showed an ideal position of each stent. The function of the pulmonary valves and hearts was not different compared with the preoperative conditions of the sheep. Anatomic examination revealed that the stent was covered by a layer of endothelial tissue with no stent fracture or valvular calcification. The histologic evaluation of the stent and surrounding tissue showed that the surface of the stent was smooth and covered by a complete layer of endothelial cells without obvious infiltration of inflammatory cells. The vascular wall was integrative without tear phenomenon in each layer of tissue.

CONCLUSIONS

These results show that pulmonary valve stents can be implanted via direct right ventricle puncture. Further studies evaluating xenograft valve material and the effect of implantation in vivo are needed.

Percutaneous Technique for Creation of Tricuspid Regurgitation in an Ovine Model

Experimental models of tricuspid regurgitation (TR) are needed to study the percutaneous placement of prosthetic atrioventricular valves. The purpose of this study was to develop an appropriate simple and reproducible percutaneous experimental model for creation of tricuspid regurgitation. Tricuspid regurgitation was successfully created through papillary muscle avulsion using a guide-wire loop in seven sheep with regurgitation documented on right ventricular angiograms and a significant increase in heart rate and right atrial pressures. Acute onset of tricuspid regurgitation was poorly tolerated in one animal that died. Autopsy examinations showed avulsion of one papillary muscle in four animals and two papillary muscles in three animals.

Pulmonary valve replacement: extending the indications to the whole spectrum of pulmonary valve disease

Pulmonary valve replacement through a transcatheter technique is currently limited to the small group of patients with a right ventricular outflow tract that does not exceed 22–26 mm in diameter. In this report, we will give an overview of ongoing work to extend the present indication to the vast majority of patients. Second-generation devices and approaches are described, both of which prepare patients to receive the currently available valved stents. The hybrid approach was the first to be applied to humans, but remains highly invasive and justifies research into pure transcatheter strategy. Therefore, it is clear that the transcatheter approach will soon represent the only valuable alternative to on-pump pulmonary valve replacement.

Is Stent Placement Effective for Palliation of Right Ventricle to Pulmonary Artery Conduit Stenosis?

OBJECTIVES

This study was designed to evaluate the outcome of stent placement (SP) for conduit discrete stenosis using predefined criteria.

BACKGROUND

Right ventricle (RV) to pulmonary artery (PA) conduits are often associated with complications, such as stenosis, requiring multiple surgical replacements.

METHODS

Patients who underwent primary or repeat SP were included. Indications for SP were clinical symptoms and/or RV to systolic blood pressure (SBP) ratio (RV:SBP) >0.65 by echocardiography. Our definition of success was a decrease in RV:SBP by >20%, a final RV:SBP ratio of <0.65, or resolution of symptoms.

RESULTS

Stents were placed successfully in 28 of 31 patients (90%), including 3 patients who underwent the procedure solely for symptoms. The RV:SBP ratio decreased (0.75 +/- 0.17 vs. 0.52 +/- 0.12, p < 0.001), and the conduit diameter increased (postero-anterior 9.1 +/- 2.9 vs. 12.0 +/- 2.8 mm, lateral 8.3 +/- 2.2 vs. 11.6 +/- 2.4 mm, p < 0.001). In the 28 patients with successful SP, 8 (29%) remained free from second intervention. In the remaining patients, the median time to re-intervention was 16 months (range 6 to 44 months). Second transcatheter interventions (4 SP, 4 balloon dilation) were successful in 8 of 13 patients. Complications included balloon rupture (n = 4), stent fracture (n = 2), and pseudoaneurysm formation (n = 1).

CONCLUSIONS

Initial SP has excellent intermediate outcomes, successfully postponing surgical intervention for the majority of patients. Conduit restenosis may be successfully treated with a second transcatheter intervention. On the basis of these data, SP is likely the procedure of choice for patients with a discrete stenosis of the RV to PA conduit.