PTCA in angulated segments: effects of balloon material, balloon length, and inflation sequence on straightening forces in an in vitro model

Evaluation of the differences in pressure applied to the vessel wall by different types of balloon remodeling microcatheters in an experimental model

BACKGROUND

We examined compliance differences among balloon remodeling microcatheters, which have not been established previously.

METHODS

Straight and 120° angulated vascular models were created in a 3 mm diameter tube with 3 mm hole (vascular model A), a tube with a 4 mm hole (vascular model B), and a 4 mm diameter tube (vascular model C). We compared the pressure exerted when each balloon was herniated 1 or 2 mm between three compliant balloons (SHOURYU SR, TransForm C, and Scepter C) and four super-compliant balloons (HyperForm, SHOURYU HR, TransForm SC, and Scepter XC).

RESULTS

In vascular model A, there was a significant difference in the pressure exerted by compliant balloons and super-compliant balloons in both the straight and angulated models. In the straight model (1 and 2 mm), the lowest pressure was exerted by HyperForm (super-compliant balloons group) and SHOURYU SR (compliant balloons group). The lowest pressure was exerted in the angulated model by HyperForm (super-compliant balloons group) and Scepter C (compliant balloons group). The Scepter balloon exerted higher pressure in the straight model than other balloon remodeling microcatheters but less in the angulated model. In vascular model B, the pressure decreased in all balloons compared with model A. In vascular model C, the pressure increased in all balloons compared with model A.

CONCLUSIONS

Pressure differed across balloon remodeling microcatheters. In addition, vessel shape and diameter, and hole size, affected the results. Our findings can help select balloon remodeling microcatheters.

Numerical model of a valvuloplasty balloon: in vitro validation in a rapid-prototyped phantom

Background

Patient-specific simulations can provide insight into the mechanics of cardiovascular procedures. Amongst cardiovascular devices, non-compliant balloons are used in several minimally invasive procedures, such as balloon aortic valvuloplasty. Although these balloons are often included in the computer simulations of these procedures, validation of the balloon behaviour is often lacking. We therefore aim to create and validate a computational model of a valvuloplasty balloon.

Methods

A finite element (FE) model of a valvuloplasty balloon (Edwards 9350BC23) was designed, including balloon geometry and material properties from tensile testing. Young’s Modulus and distensibility of different rapid prototyping (RP) rubber-like materials were evaluated to identify the most suitable compound to reproduce the mechanical properties of calcified arteries in which such balloons are likely to be employed clinically. A cylindrical, simplified implantation site was 3D printed using the selected material and the balloon was inflated inside it. The FE model of balloon inflation alone and its interaction with the cylinder were validated by comparison with experimental Pressure–Volume (P–V) and diameter–Volume (d–V) curves.

Results

Root mean square errors (RMSE) of pressure and diameter were RMSE_P = 161.98 mmHg (3.8 % of the maximum pressure) and RMSE_d = 0.12 mm (<0.5 mm, within the acquisition system resolution) for the balloon alone, and RMSE_P = 94.87 mmHg (1.9 % of the maximum pressure) and RMSE_d = 0.49 mm for the balloon inflated inside the simplified implantation site, respectively.

Conclusions

This validated computational model could be used to virtually simulate more realistic valvuloplasty interventions.

Comparison of slow oscillating versus fast balloon inflation strategies for coronary angioplasty

Previous studies suggest that slow and/or oscillating balloon inflation during coronary angioplasty may decrease the incidence of coronary dissection and improve clinical outcomes. To compare the effect of slow oscillating versus conventional fast inflation techniques on the incidence of severe coronary dissection during angioplasty, 622 patients were randomized to slow oscillating inflation versus fast inflation. Angiographic outcomes of the procedures and in-hospital clinical events were recorded. The primary end point of severe (type C, D, E, F) dissection occurred in 7.7% of patients undergoing slow oscillation and 6.6% of patients undergoing fast inflation (p = 0.87). Major complications (death, urgent coronary artery bypass graft surgery, stroke, abrupt closure, or Q-wave myocardial infarction) occurred in 4.7% of patients undergoing slow oscillation and 3.5% of patients undergoing fast inflation (p = 0.45). The 2 inflation strategies did not differ in the pressure at which the balloon achieved full expansion, angiographic success rate, residual stenosis, and incidence of all minor and/or major complications. We conclude that there is no benefit of slow oscillating inflation over routine fast inflation in angioplasty. Slow oscillating inflation did not dilate lesions at lower pressures, decrease the incidence of dissection or severe dissection, or reduce the incidence of adverse clinical outcomes.