Cath Lab Imaging Considerations for Peds

Like adults, children may need to undergo catheterization procedures. What are the considerations when these young patients require cath lab imaging exams? Two pediatric cath labs, the Children’s Hospital of Philadelphia (CHOP) and Cincinnati Children’s Hospital Medical Center, share strategies to help lower dose and improve care for this smaller, and often more fragile patient population.

Children’s Hospital of Philadelphia (CHOP)

Rotational angiography equipment within the CHOP cath lab allows images to be acqiured in 35 seconds, enhancing pediatric procedural planning and work-up. Source: The Children's Hospital of Philadelphia

Matthew J. Gillespie, MD, attending cardiologist at CHOP and assistant professor of pediatrics, Perelman School of Medicine at the University of Pennsylvania

Snapshot:

• Procedures: CHOP performs more than 850 open and closed pediatric heart surgeries per year.
• Success rate: Between 2006 and 2010, staff at CHOP performed 2,656 total procedures with a mortality rate of 3.7 percent.
• Ranked: #2 best children’s hospital for cardiology and heart surgery by U.S. News & World Report
• Most common types of cardiac pediatric procedures: Closing atrial septal defects or ventricular septal defects; Balloon valvularplasty to repair a stenotic aortic valve, a mitral stenosis, mitral valve prolapse or a stenotic pulmonary valve; Cardiac catheterizations to enlarge the aorta or enlarge pulmonary arteries when they are narrowed; Valve replacement procedures

Imaging procedures
“The cath lab is the backbone of CHOP,” Gillespie says. “Within it, x-ray often becomes the standard imaging-based procedure used to guide most pediatric catheterization procedures.”

In addition to ultrasound and echo, CHOP uses rotational angiography (syngo DynaCT, Siemens Healthcare) to acquire images. Images are available within 35 seconds, enhancing procedural planning, mapping and workup.

“The C-arm is the workhorse of the imaging technology we use,” Gillespie offers. “The C-arm rotates 220 degrees and provides us with the same tomographic 3D image slices as a traditional CT scanner.” At CHOP, physicians register MR images with fluoroscopy-based images to create an MRI-based roadmap, which is helpful when placing stents or valves, he says.
 

Cincinnati Children’s

Biplane angiography systems in two hybrid cath labs at Cincinnati Children's handle a full range of diagnostic cases and treat complex anatomies. Source: Cincinnati Children's Hospital Medical Center

Russel Hirsch, MD, director of the cardiac cath lab at Cincinnati Children’s Hospital Medical Center in Ohio

Snapshot:

• Procedures: 850 cardiology procedures per year
• Ranked: #9 best children’s hospital for cardiology and heart surgery by U.S. News & World Report
• Most common pediatric imaging modalities used: Fluoroscopy; Echocardiography: A combined audio-visual system—an imaging routing system—is connected to the echo machine and every image can be viewed on one screen; Intravascular ultrasound  

Hybrid approach
Two state-of-the-art multifunctional cardiac cath labs are housed within Cincinnati Children’s Hospital Medical Center, where staff performs a multitude of hybrid cardiac cath lab procedures. An ongoing goal of the hospital has been minimizing anesthesia exposure. This is a particular problem for pulmonary hypertension patients, as anesthesia holds a high risk for mortality, says Hirsch.

Therefore, for this patient population, often different procedures are performed under the same anesthetic. “It’s a very versatile environment and it allows us to look after the patient, ensuring that the patient is exposed to the least risk as possible,” Hirsch says.

“While there are some procedures that should be done in the operating room and some that should be performed in the cath lab, there is often a grey area,” says Hirsch. Enter hybrid rooms.

The hybrid approach is useful with babies because there is difficult cath lab manipulation that can lead to arrhythmias. Also, the hybrid approach is helpful when placing stents or valves, or when the ventricular or branch pulmonary arteries need work.

Lowering Radiation Dose

Children's Hospital of Philadelphia (CHOP) and Cincinnati Children’s Hospital seek to keep radiation dose in pediatric patients as low as possible through protocols that are constantly monitored and adjusted. “We partly get excited about high-grade MRI because we can perform nearly 90 percent of the diagnostic and anatomic work-up before we even step into the cath lab and step on the x-ray pedal,” says Matthew J. Gillespie, MD, attending cardiologist at CHOP. While he says that CT scanning gives an “incredibly detailed image,” it usually comes at the cost of a high radiation dose. “Dose becomes important because the overall effective dose can be larger in smaller patients in terms of what is absorbed,” Gillespie says.   Russel Hirsch, MD, director of the cardiac cath lab at Cincinnati Children's Hospital, says its biplane angiography system (Allura Xper FD 10/10, Philips Healthcare) helps reduce radiation risk. “We can significantly reduce dose and contrast by performing an angiogram, because it gives twice the information with a single contrast dose—5 mm/kg to 6 mm/kg per procedure,” he says. The key to lower radiation doses, says Hirsch, is decreasing the frame rate. “Gone are the days of a standard 30-frame per second exam. Now we are down to 15 frames per second and sometimes get as low as 7.5 frames per second,” he says. Additionally, protocols that allow for prospective or retrospective storage of fluoroscopy runs have considerably reduced dose. “We think twice, sometimes three times before committing our pediatric patients to the cath lab,” Hirsch says. “If there is a non-invasive way to obtain the images—MRI or the occasional echo—we will do it.”