From the Journals

Expandable cardiac valve in children found feasible

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Alternative to fixed-diameter prostheses

In his invited commentary, Carl L. Backer, MD, of Northwestern University, Chicago, noted three advantages of the use of the stent-expandable bovine valve for infants and children: It can be used when no prosthetic is small enough to fit in the annulus, it does not require anticoagulation with warfarin after placement, and it can be dilated as the child grows (J Thorac Cardiovasc Surg. 2016 Dec:152[6];1524-5).

But, Dr. Backer added, “one note of caution that I would raise relates to the late complications noted in previous trials with tissue valves on the left side of the heart in children.” He noted such experience had been reported with the Mitroflow bovine pericardial bioprosthesis (LivaNova) (Circulation. 2014;130[1];51-60) and the Perimount Magna (Edwards Lifesciences) (Ann Thorac Surg. 2016;102[1];308-11). “The follow-up of Emani and colleagues at two years is good; however, there is always the possibility that premature calcification and stenosis of these valves, particularly those placed on the left side of the heart, could lead to the need for early explantation,” Dr. Backer said.

Nonetheless, the findings of Dr. Emani and his colleagues showed that the concept of implanting a stented jugular vein graft valve in infants and young children “is proving to be safe and efficacious,” Dr. Backer said. “In these children for whom there are limited options, this appears to be an important addition to our surgical strategies,” he concluded.

Dr. Backer had no financial relationships to disclose.



Young children and infants who require cardiac valve replacement are limited to fixed-diameter prostheses that cannot accommodate their growth, but researchers at Boston Children’s Hospital have reinforced an expandable bovine jugular vein graft using an external stent and implanted it in 42 patients with acceptable short-term results, according to a report in the Journal of Thoracic and Cardiovascular Surgery.

In 4 years, the modified Melody valve (Medtronic) has proved amenable to enlargement via catheterization as the child grows, Sitaram M. Emani, MD, and coauthors said. “The valve was competent with low gradient acutely postoperatively in all patients,” Dr. Emani and his coauthors said (J Thorac Cardiovasc Surg. 2016 Dec;152[6]:1514-23).

Dr. Sitaram Emani

Dr. Sitaram Emani

This may provide another option to the fixed-diameter, prosthetic valves that have been used traditionally to replace semilunar or atrioventricular (AV) valves in children. As the recipients of these valves grow, they need subsequent operations for replacement with larger valves. Children who have allograft conduits implanted in the right ventricular outflow tract (RVOT) position can delay reoperation with catheter-based valve expansion, but that has been associated with valvular insufficiency (J Thorac Cardiovasc Surg. 2009;138[4]:911-6). Placement of an oversized valve can improve long-term conduit durability but is not always feasible (Ann Thorac Surg. 2013;96[5]:1695-702).

The Melody valve is approved for transcatheter implantation into the RVOT and can be modified for the semilunar or AV positions, Dr. Emani and his coauthors said. The valve has achieved competence within a size range of 10-22 mm.

The researchers implanted the valve in four positions: RVOT (14), mitral (24), aortic (one), or tricuspid (three). The median age at implantation was 10 months, with a range of 3 weeks to 5.8 years. The patients had an average of one previous valve replacement or repair procedure.

Six deaths occurred in the study population; three before discharge. Those three patients had replacement to salvage a moribund circulation in the setting of mechanical circulatory support and severely depressed ventricular function. The other three patients who died were able to demonstrate adequate valve function, and autopsy did not show any signs of valvular thrombosis or deterioration, the researchers said.

Using Kaplan-Meier analysis, Dr. Emani and his coauthors estimated the freedom from death or transplantation was 83% at 12 months and 77% at 24 months.

The average time between catheter-based dilations was around 10 months, they wrote, “but this might be increased by more aggressive dilation.” Early in the study, the researchers were not aggressive with dilations because of concerns about valve injury, but then they found that patients tolerated increases in valve diameter by as much as 4 mm.

“Further investigation is needed to determine whether the device retains expandability over the long term after multiple dilations,” Dr. Emani and his coauthors said.

Further refinements in valve design and implantation techniques may lead to prevention of reoperation and perivalvular complications, they suggested.

The researchers did note a couple limitations of their study: the heterogeneous cohort prohibits any generalization of the outcomes, particularly mortality, and concomitant procedures performed during the valve replacement would affect mortality.

Dr. Emani and his colleagues had no financial relationships to disclose.

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