The Digestive Health Institute at UCI Health has developed a groundbreaking new method to measure blood pressure in the liver — the single best benchmark for assessing liver health.
As cases of nonalcoholic fatty liver disease rise due to America’s obesity epidemic, this diagnostic tool could help millions, according to UCI Health gastroenterologist Dr. Kenneth J. Chang, who developed the new technique called endoscopic ultrasound-guided portal pressure gradient (EUS-guided PPG).
“If you tell me what your liver pressure is, I can tell you how likely you are to die of liver disease, to have liver cancer, to need a transplant in the next five years,” says Chang, executive director of the Digestive Health Institute (DHI).
In the eight years since Chang began researching ways to test liver pressure, nonalcoholic fatty liver disease (characterized by excess fat in the liver) has become increasingly common.
It has a benign form called simple fatty liver and a harmful form called nonalcoholic steatohepatitis (NASH). Symptoms are hard to detect until the disease is advanced.
No. 1 reason for liver transplant'
“In 2020, NASH has overtaken hepatitis as the No. 1 reason Americans need a liver transplant,” Chang says. “It’s now the most prevalent cause of liver disease, cirrhosis and liver death.”
By knowing their liver blood pressure, patients can act early enough to reverse the progression of liver disease, even avoid a transplant, through weight loss, medication and eliminating alcohol consumption.
But it is hard to get an exact reading because the standard test for portal hypertension (high blood pressure in the liver) usually requires an incision in the neck. It’s also an indirect method, since one of two key blood vessels needed for an accurate reading can’t be reached from outside the liver.
Chang, a leader in interventional endoscopy, previously had developed minimally invasive techniques for imaging and performing needle biopsies of the liver and pancreas with the aid of endoscopic ultrasound (EUS).
Applying endoscopic ultrasound
This involves guiding tubes with an imaging device and needle through the mouth into the digestive tract. Knowing that EUS provides clear images of both key liver blood vessels, he began investigating how to use the technology to test portal hypertension.
“If we can attach a pressure gauge to the tiny needle, measure the pressure directly and then take the needle out, there’s no cutting in the neck. It’s just a scope in the stomach. The patient is completely under anesthesia, and it takes about 15 to 20 minutes.”
Using a handheld pressure gauge, Chang initially studied the procedure in pigs.
“We found that the pressure reading was accurate even down to the smallest needle. We compared that with the pressure reading they were getting from the catheter going through the neck vein and it was identical,” he says.
Spreading the knowledge
Next, Chang led a pilot study in humans and showed the procedure could be done safely and accurately. The U.S. Food and Drug Administration recently approved the device, which was developed in partnership with Cook Medical.
“UCI is now leading a worldwide, multicenter trial to make sure that the experience we have shown here would be similar anywhere in the world,” he says. “We’re also providing training for key doctors from around the United States, Europe and Asia so they can acquire the skills to help patients all over the world.”
The novel coronavirus pandemic, which has necessitated virtual training in most things, ironically has allowed even more physicians to learn the procedure, Chang says. Within a few years, he expects EUS-guided PPG to be offered at most major U.S. hospitals.
“We’ve developed something truly disruptive, groundbreaking and innovative,” he says. “It’s unreal that it went from just an idea to becoming a device and now a strategy to fight liver disease.”