What should be the balloon diameters for kissing balloon inflation in bifurcation stenting?

Balloon Sizing for Kissing Balloon Inflation in Bifurcation Stenting

Use the formula R² = D₁² + D₂² to determine optimal kissing balloon diameters, where D₁ and D₂ are the diameters of balloons sized to match the distal main vessel and side branch reference diameters, and R represents the predicted proximal main vessel expansion. 1

Sizing Strategy

Primary Balloon Selection

• Size each balloon to match its respective downstream vessel reference diameter (not the stented segment), with the main vessel balloon matched to the distal main branch and the side branch balloon matched to the side branch reference diameter 1
• This mathematical relationship (R² = D₁² + D₂²) has been clinically validated by volumetric intravascular ultrasound, showing that actual stent expansion correlates significantly with the predicted theoretical diameter (r=0.76, p=0.0003) 1
• The ratio of actual to theoretical stent expansion is highly consistent between proximal and distal segments (93.1% vs 93.4%) despite more elliptical proximal dilation 1

Technique Modifications

Minimize balloon overlap in the main vessel during kissing balloon inflation to prevent stent deformation and overexpansion 2, 3

• Modified kissing balloon technique (mini-KBI): Position the proximal marker of the side branch balloon just at the level of the upper edge of the side branch ostium, rather than extending 3mm or more into the main vessel 2
• This approach reduces the deformation index from 0.25 ± 0.02 (classical technique) to 0.06 ± 0.01 (modified technique, p<0.001) while maintaining adequate side branch ostium opening 2
• Minimal balloon overlapping (MBO) guidelines produce more consistent maximal dilation points compared to operator discretion, which results in variable stent configurations 3

Mandatory Post-Kissing Optimization

Always perform final proximal optimization technique (POT) after kissing balloon inflation using a single balloon sized to the proximal main vessel reference diameter 4, 5

• Kissing balloon inflation alone produces asymmetrical proximal stent expansion with significant malapposition (33.4% of struts malapposed) and increased eccentricity (index 0.72) 5
• Final proximal inflation reduces malapposition from 33.4% to 0.6% (p=0.02), improves eccentricity index from 0.72 to 0.90 (p<0.001), and increases minimum stent area from 6.8mm² to 8.5mm² (p<0.0001) 5
• This step is mandatory after elective double stenting according to ACC/AHA guidelines to optimize clinical outcomes 6, 4

Clinical Context and Pitfalls

Guideline Framework

• Final kissing balloon inflation is supported by clinical evidence after elective double stenting, with provisional side-branch stenting recommended as the initial approach for most bifurcation lesions 6
• Intravascular imaging (IVUS or OCT) is reasonable to optimize kissing balloon inflation techniques and assess wire recrossing points in complex bifurcations 6

Common Pitfalls to Avoid

• Avoid excessive balloon overlap in the main vessel (>3mm), which causes the "bottleneck" effect and stent deformation that cannot be effectively corrected even with subsequent POT 2
• Do not size balloons to the stented segment—always reference the native vessel diameters distal to the bifurcation 1
• Never skip final proximal optimization—kissing balloon inflation alone leaves significant proximal malapposition that increases thrombosis and restenosis risk 5
• Be aware that proximal segments will dilate more asymmetrically (symmetry index 0.77 ± 0.08) compared to distal segments (0.88 ± 0.03, p<0.0001), which is expected and predicted by the formula 1

Stent-Specific Considerations

• Two-link stents open the side branch more effectively but risk proximal strut overdilatation, while three-link stents better preserve structural integrity during kissing balloon inflation 3