Dual balloon technique for valvuloplasty of aortic stenosis in adults.

A dual balloon technique was studied in 16 patients with aortic stenosis in whom results with a single balloon (up to 20 mm, 5.5 cm or 25 mm, 3.0 cm in diameter and length, respectively) were judged to be suboptimal. Dual balloon valvuloplasty was performed using 2 balloons advanced and inflated simultaneously across the stenotic aortic valve orifice. For the group as a whole, the average peak transvalvular gradient was reduced from 79 +/- 8 to 57 +/- 7 mm Hg (mean +/- standard error) using a single balloon (p less than 0.0005), and reduced further to 36 +/- 4 mm Hg using dual balloons (p less than 0.0005 compared with single balloon results). Similarly, calculated aortic valve orifice area was increased from 0.45 +/- 0.04 to 0.57 +/- 0.05 cm2 using a single balloon (p less than 0.0005), and further increased to 0.77 +/- 0.06 cm2 using dual balloons (p less than 0.0005). Dual balloon dilation caused no complications directly attributable to the use of 2 balloons, including no exacerbation of aortic regurgitation. These results suggest that dual balloon valvuloplasty is safe and efficacious in selected patients with aortic stenosis.

Mechanism of aortic balloon valvuloplasty: fracture of valvular calcific deposits.

Balloon valvuloplasty has been shown to acutely reduce the hemodynamic and symptomatic severity of calcific aortic stenosis. The mechanism by which this improvement is accomplished is not known. At necropsy, three patients who died after hemodynamically successful aortic balloon valvuloplasty were found to have aortic valve calcific deposits fractured at one or more sites. These findings suggest that fracture of leaflet calcium represents the basis for successful aortic balloon valvuloplasty.

Percutaneous, in vivo excimer laser angioplasty: results in two experimental animal models.

Pulsed ultraviolet light from an excimer laser was successfully transmitted via conventional fused silica optical fibers and used to accomplish recanalization of stenotic or totally occluded arteries in an intact, flowing blood field of two atherosclerotic animal models. The fibers, 300-600 micron in diameter, were delivered percutaneously in wire-guided multilumen catheters and then used to transmit wavelengths of 308 or 351 nm from excimer lasers with pulse durations of 12 nsec or less. Lesions from 70-100% diameter narrowing, and 0.6 to 5.5 cm in length were successfully recanalized (less than 50% residual diameter narrowing) in eight animals, using 3-4 J/cm2/pulse, 10-50 Hz, and 48-370-sec cumulative exposure. Necropsy examination in six of the eight animals disclosed no signs of thermal injury. Perforations were observed in four of eight animals. Thus, while use of an excimer laser power source did not obviate vascular perforation as a complication of laser angioplasty, these preliminary results indicate that energies of pulsed ultraviolet light sufficient to ablate atherosclerotic plaque can be both transmitted via conventional fused silica optical fibers and used successfully within an intact, flowing blood field. It may therefore be possible to use pulsed ultraviolet light from an excimer laser to accomplish percutaneous ablation of atherosclerotic arterial obstructions in humans.

In vitro analysis of mechanisms of balloon valvuloplasty of stenotic mitral valves.

Preliminary reports indicate that percutaneous balloon valvuloplasty is efficacious for treatment of mitral stenosis. The present study was designed to evaluate whether anatomic features of stenotic mitral valves in older adults affect the efficacy of balloon valvuloplasty and to determine the mechanism by which increased orifice area is accomplished. Fifteen mitral valves excised intact at the time of mitral valve replacement from patients with no more than 2+/4+ mitral a regurgitation were selected for study. Balloon valvuloplasty was performed using a sequence of dilation catheters with balloons 18 to 25 mm in inflated diameter. Mitral valve area, measured with a conical valve sizer, increased from 0.71 +/- 0.06 cm2 (mean +/- standard error of the mean) to 1.77 +/- 0.19 cm2 (p less than 0.0001) after valvuloplasty, resulting in an increase in calculated orifice area of 185 +/- 27% (range 34 to 407%). The increase in calculated orifice area correlated inversely with orifice area before valvuloplasty (r = -0.57; p = 0.026), but was unrelated to extent of calcific deposits on the prevalvuloplasty x-ray of the excised mitral valve. Gross examination together with x-ray analysis after valvuloplasty revealed that the mechanism of balloon valvuloplasty in each case involved commissural splitting, including splits through heavily calcified commissures, without grossly apparent detachment of tissue fragments. These findings suggest that balloon valvuloplasty augments the functional mitral valve orifice area in a manner analogous to standard surgical commissurotomy, and balloon valvuloplasty is likely to be efficacious for a wide spectrum of adult mitral valvular stenosis, including severe stenosis with extensive calcific deposits.