Abstract
Stent delivery failure to the distal lesion was still encountered even after the introduction of mother–child technique using a 5 F or 4 F child catheter. A 5 F inner catheter with a length of 112 cm, and a 4 F inner catheter with a length of 122 cm enabled a novel mother–child–grandchild technique. In in vitro experiments, not only was backup support increased, but superior trackability could also be obtained with the mother–child–grandchild technique, over the mother–child technique. We describe the clinical data using this novel mother–child–grandchild technique to deliver a stent to the severely bended and/or calcified distal lesion.
1
Introduction
Many stent delivery techniques have been developed for difficult situations . An inner catheter is particularly helpful if increased backup support is needed during a procedure when the wire has already been inserted with difficulty through a guide catheter of conventional length. The principle role of an inner catheter is to combine the advantages afforded by the passive support of a large mother guide catheter, with the ability to insert a smaller inner catheter further into the target vessel, without damaging the arterial segment proximal to the lesion . Recently, extra-deep engagement of a 4 F inner catheter enabled stent delivery even though the distal lesion in clinical practice. However, stent delivery failures have still been encountered after using a 4 F inner catheter . Here we developed a mother–child–grandchild catheter system for difficult stent delivery cases.
2
Methods
2.1
Profile of guide system
The length of the 5 F child catheter (i-works, Medikit, Japan) is 112 cm, 12 cm longer than a conventional guide catheter. The length of the 4 F grandchild catheter (i-works) is 122 cm. The inner diameter of the 4 F catheter is 1.26 mm (0.050 inch), and the inner diameter of the 5 F child catheter is 1.50 mm, (0.059 inch); larger than the outer diameter of the 4 F inner catheter (1.43 mm, 0.056 inch). The inner diameter of the mother guide catheter should be more than 1.80 mm (0.070 inch) to accommodate the outer diameter of a 5 F child catheter (1.70 mm, 0.067 inch). Thus, the mother–child–grandchild system is a method of inserting a 4 F grandchild catheter and a 5 F child catheter into a guide catheter larger than 6 F in order to increase backup support and trackability ( Fig. 1 A ).
2.2
In vitro experiments
The backup support of the guide catheter was measured in vitro using an experimental system. The artery model was filled with water kept at 37 °C. A guide catheter was engaged into the ostium of the artery model ( Fig. 1 B). Then a 2.5/15 mm balloon was pushed into the artery model along a standard 0.014-inch guidewire at a constant speed of 5 mm/s using a force gauge machine. The pushing force of the gauge machine represented the resistance of a balloon. The maximal backup support of the guide catheter was thus defined as the pushing force of the gauge machine when the guide catheter disengaged from the coronary system. The backup support was measured for 6 F alone, 5–6 system and 4–5–6 system using the same coronary artery model. Each measurement was repeated 5 times. In 5–6 system, the backup support was measured while protruding the 5 F catheter into the artery model out of the outer 6 F catheter by 10 mm. In 4–5–6 system, the backup support was measured while protruding the 4 F catheter into 5–6 system by 10 mm. Data were expressed as mean ± standard deviations. Comparison of continuous variables between equivalent groups was calculated by ANOVA. p value ≥ 0.05 was considered statistically insignificant. The trackability of the 6 F alone, 5–6 system and 4–5–6 system was assessed by the length (cm) between the ostium and the tip of catheter system.
2
Methods
2.1
Profile of guide system
The length of the 5 F child catheter (i-works, Medikit, Japan) is 112 cm, 12 cm longer than a conventional guide catheter. The length of the 4 F grandchild catheter (i-works) is 122 cm. The inner diameter of the 4 F catheter is 1.26 mm (0.050 inch), and the inner diameter of the 5 F child catheter is 1.50 mm, (0.059 inch); larger than the outer diameter of the 4 F inner catheter (1.43 mm, 0.056 inch). The inner diameter of the mother guide catheter should be more than 1.80 mm (0.070 inch) to accommodate the outer diameter of a 5 F child catheter (1.70 mm, 0.067 inch). Thus, the mother–child–grandchild system is a method of inserting a 4 F grandchild catheter and a 5 F child catheter into a guide catheter larger than 6 F in order to increase backup support and trackability ( Fig. 1 A ).
2.2
In vitro experiments
The backup support of the guide catheter was measured in vitro using an experimental system. The artery model was filled with water kept at 37 °C. A guide catheter was engaged into the ostium of the artery model ( Fig. 1 B). Then a 2.5/15 mm balloon was pushed into the artery model along a standard 0.014-inch guidewire at a constant speed of 5 mm/s using a force gauge machine. The pushing force of the gauge machine represented the resistance of a balloon. The maximal backup support of the guide catheter was thus defined as the pushing force of the gauge machine when the guide catheter disengaged from the coronary system. The backup support was measured for 6 F alone, 5–6 system and 4–5–6 system using the same coronary artery model. Each measurement was repeated 5 times. In 5–6 system, the backup support was measured while protruding the 5 F catheter into the artery model out of the outer 6 F catheter by 10 mm. In 4–5–6 system, the backup support was measured while protruding the 4 F catheter into 5–6 system by 10 mm. Data were expressed as mean ± standard deviations. Comparison of continuous variables between equivalent groups was calculated by ANOVA. p value ≥ 0.05 was considered statistically insignificant. The trackability of the 6 F alone, 5–6 system and 4–5–6 system was assessed by the length (cm) between the ostium and the tip of catheter system.
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