‘Mother-Child’ Technique Improves Success for PCI in Challenging Lesions

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Inserting a 4-Fr catheter into a 6-Fr guiding catheter—the so-called mother-child technique—greatly improves the success rate for treating lesions in which standard methods have failed. The “4-in-6” system may become a viable alternative for highly calcified, angular, or tortuous lesions, according to a paper published online March 1, 2011, ahead of print in Circulation: Cardiovascular Interventions.

Satoshi Takeshita, MD, of Shonan Kamakura General Hospital (Kamakura, Japan), and colleagues looked at 51 consecutive patients who underwent PCI via the mother-child technique using a 4-Fr catheter (manufactured both by Terumo and Asahi Intecc). The technique was chosen at operator discretion when previous attempts at conventional PCI failed to cross the lesion.

The majority of vessels treated were right coronary (41%), followed by left anterior descending (33%), circumflex (22%), and bypass grafts (4%). By far, the most common lesion morphology was type C (82%). A minority of lesions were type B2 (18%).

Showing Promise In Vivo, In Vitro

In these formerly resistant lesions, the mother-child technique achieved target lesion percent diameter stenosis of less than 50% in 48 lesions (94%). Stent deployment was attempted in 44 cases (86%), of which 40 were successful (91%). A variety of DES were implanted. Overall, 94% of patients not only had their lesions crossed but also were free of in-hospital MACE including cardiac death, MI, and TLR.

The main obstacles to procedural success were severe calcification and tortuosity of either the proximal segment or target lesion. Two instances of stent dislodgment occurred during withdrawal of the stent delivery system into the child catheter. Because these stents could not be retrieved, they were deployed or crushed at nontarget coronary segments.

Another issue is that the small diameter of the 4-Fr child catheter prevents the use of IVUS and some stent or balloon types.

In vitro experiments using a coronary artery tree model demonstrated that backup support with the 4-in-6 method was similar to that achieved with a 6-Fr guiding catheter. Although support was increased when the 4-Fr catheter was advanced into the coronary tree at least 5 cm beyond the tip of the mother guiding catheter (P = 0.01), it did not exceed what was provided by a 7-Fr guiding catheter. On the other hand, the 4-Fr catheter offered superior trackability over a previous 5-in-6 incarnation (median 15.0 vs. 13.0 cm; P < 0.005).

Trying Too Hard?

In an e-mail communication with TCTMD, Dr. Takeshita said, “The clinical results were very impressive, because [almost] all of the lesions were successfully treated by using this new technique after failure of conventional techniques, including buddy wire technique, anchor balloon technique, lesion modification with rotablator, and 5-in-6 mother-child technique.” Though a learning curve exists, he noted, it amounts to 5 to 10 cases.

The few instances of stent dislodgement happened when operators tried to retrieve stents after failed delivery, he said. “However, after the learning curve, we experienced no such cases. It is important to advance the child catheter as close as possible to the target lesion, or advance the child catheter beyond the lesion.”

Sorin J. Brener, MD, of Weill Cornell Medical College (New York, NY), seemed impressed by the results but cautioned that it all comes down to trust. “Usually, when doing studies like this, at first you try very perfunctorily and say, ‘We couldn’t do it.’ And then you do this technique and [it] looks remarkable,” he told TCTMD in a telephone interview. “But if we believe that they tried hard and couldn’t succeed, and now they got 94% success, that’s a good deal.”

Similarly, David E. Kandzari, MD, of Piedmont Heart Center (Atlanta, GA), noted, “The fact that at least 2 stents were dislodged implies the operators were really trying to deliver.”

Such is the risk of technologies that improve deliverability, he explained in a telephone interview with TCTMD. Although that quality is always desirable, it may encourage operators to test the limits.

“It’s analogous to giving your 16-year-old son a Ferrari. He’s not going to switch from first to second gear at 2 or 3 thousand rpms. He’s going to redline it every time. It’s the same concept,” Dr. Kandzari commented. “We get these new products that have the perception and marketing around them of deliverability and push them to the limits oftentimes, and it can result in complications like stent retention issues.”

Balancing Support and Trackability

Though technology for the mother-child technique has been available internationally for some time, especially in Japan, it was not marketed in the United States until recently, when Vascular Solutions (Minneapolis, MN) introduced the Guideliner catheter. The product also employs a mother-child approach, though its design is somewhat different. Importantly, Dr. Kandzari noted, it comes in a range of sizes, so that larger catheters can be used when possible in an attempt to increase backup support and smaller catheters can be used when attempting transradial access.

“We don’t use [the Guideliner catheter] that frequently, but for very challenging cases rather than more conventional techniques, this is actually a fairly user-friendly technology. It is oftentimes more convenient and possibly more supportive than historical techniques such as anchor balloon or placing a buddy wire down the artery,” he said.

“This technology is not for every interventional procedure by any means,” Dr. Kandzari cautioned, “but mostly reserved for very challenging cases of complex anatomy with angulation, tortuosity, or calcification.”

Dr. Brener agreed that the mother-child technique is particularly helpful for transradial cases. In general, interventionalists “need to be aware of the technique and utilize it when they cannot do the procedure without it. But they need to understand that there are alternatives. For example, if there’s just calcification, one alternative is to just do a rotational atherectomy first to remove the calcium and everything will pass easier,” he said, noting the approach appears to be “a very good solution” for tortuosity.

“It’s just a good weapon to have in the armamentarium,” Dr. Brener concluded.

 

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Source:
Takeshita S, Shishido K, Sugitatsu K, et al. In vitro and human studies of a 4F double-coaxial technique (“mother-child” configuration) to facilitate stent implantation in resistant coronary vessels. Circ Cardiovasc Interv. 2011;Epub ahead of print.

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