Everyone is born with a hole in the heart. During pregnancy, this hole allows blood to bypass the foetal lungs — which aren’t yet working — and deliver oxygen to the unborn baby’s heart and brain. The small opening, located between the left and right chambers, usually closes on its own within a few months after birth. But in about 1 in 4 babies, it never does. Most of those babies will be fine, and will live their lives not even knowing it. But for some, the defect can prove dangerous.
Dina McPherson, a film and television screenwriter and producer in Melbourne, Australia, was one of them. For as long as she can remember, she had suffered migraines — not typical headaches, but auras: flashing lights, blurry vision, tingling and numbness in her hands, feet and face. One scary episode left her with permanently impaired vision, another with a numb and clumsy arm that lasted for weeks. After tests, doctors found she had a patent foramen ovale, or PFO — a hole in the heart that hadn’t closed — and an MRI scan revealed she had experienced at least one stroke, which was the likely cause of her worst symptoms.
“I became terrified of doing anything,” she says. “I gave up exercise. I wouldn’t carry the shopping, or do anything that strained me, stressed me or even excited me. This was no way to live.”
For the majority of people who have one, a PFO is of no health consequence, even though blood continues to leak from the right atrium to the left, according to the American Heart Association. It becomes a problem — as it did for McPherson — only when blood moving through the portal contains a clot that reaches the brain.
“The theory is that a small clot forms in one’s veins, and this clot would typically be filtered out by the lungs and cause no problems,” says James A. Thompson, an interventional cardiologist at Inova Fairfax Hospital, who uses catheterisation to correct structural heart problems in children and adults. “However, if one has a PFO and that clot crosses the PFO and goes to the left side of the heart, it can go to the brain and cause a stroke.”
The theory is that a small clot forms in one’s veins, and this clot would typically be filtered out by the lungs and cause no problems.
While a PFO occurs in only about 25 per cent of the general population, up to half of stroke patients with no other identifiable risk factors for stroke have one, according to the heart association. “It is a potentially serious condition,” Thompson says. In fact, he adds, “I implore all patients who have had a stroke and have no clear cause and don’t have traditional risk factors to make sure they don’t have a PFO,” he says.
PFOs often are missed, and should be diagnosed by a physician with experience in identifying them, he says. They can be detected by echocardiogram with saline contrast, sometimes called a bubble study. Thompson prefers a type of ultrasound called transcranial Doppler, or TCD, with saline contrast. Both are performed in conjunction with a Valsalva maneuver, in which the patient blows into a small tube with resistance, “much like trying to blow up a balloon that is hard to blow up,” Thompson says.
Both techniques can pick up a PFO, but the latter is more sensitive, he says. More sensitive means that it is more likely to detect a shunt that an echocardiogram does not detect. “Though sometimes increased sensitivity of a test leads to more false positives, that is not always the case and I have not found that to be true in this case. I have never taken someone to the lab after doing a TCD to close their PFO and not found one.”
Saline contrast is used to help see the defect more clearly. “One cannot typically see the PFO itself very well, but rather the effect of the PFO, which is to allow blood from the right side of the heart to pass to the left side of the heart without first having to go through the pulmonary capillaries — that is, the lung arteries. The lungs typically filter out the tiny micro-bubbles caused when we inject salt water. The echo shows the bubbles in the heart directly, while the TCD shows the bubbles getting to the brain, which is the end result of what we are worried about if a clot gets through the PFO to the brain,” he says.
The purpose of the Valsalva maneuver is to accentuate the blood going from the right atrium to the left atrium by raising the pressure in the right side of the heart. “If this is not done well, the PFO can be easily missed,” Thompson says.
When a PFO is discovered, some physicians prescribe blood thinners or antiplatelet therapy to prevent clots from forming. But in patients who have had a stroke, most experts believe the hole needs to be closed. Traditionally, closure meant using a device threaded through a catheter and opened, like an umbrella, in the heart. The lining of the heart grows over the device, sealing the hole. But in rare cases there can be side effects, including infections, clots and allergic reactions.
Recently, however, a less invasive procedure called NobleStitch has been used in Europe, and Thompson has performed it more than 100 times. It appears to be just as effective as the umbrella-like device, he says, with no apparent side effects, and it is covered by insurance.
One European study found good early results with NobleStitch; Thompson is conducting a trial as well. “Our preliminary data show the same or better closure rates than the traditional devices and safer for our patients,” he says.
The procedure involves using a catheter to deliver sutures directly to the hole and stitching it up, much as with a needle and thread. “The NobleStitch delivers two sutures through a catheter,” Thompson explains. “The [physician] cinches a knot up to the [heart] wall and tightens it like a purse string, pulling the two flaps of the wall together and sealing up the defect, leaving nothing behind other than a tiny knot of polypropylene — the same material heart surgeons all over the world use every day.”
Thompson is thought to be the only physician performing this procedure in the United States. He learned it from its inventor, biomedical engineer Anthony Nobles, whose company is based in Southern California. “We are starting to arrange other US physicians to come observe cases so we can select others to train over the coming months,” says Thompson, who says that he has no financial interest in Nobles’s company and that he is not paid by the company to perform the procedure. “Many physicians perform PFO closure in the US; they’re just using the previous generation of devices. As more physicians learn about this procedure, more will want to be trained.”
Several studies have shown that closure of a PFO dramatically reduces a patient’s risk of recurrent stroke compared with treating with medicine alone.
Some people who suffer from severe migraines — regardless of whether they have had a stroke — can be helped by PFO closure, regardless of how it is done.
“We stumbled upon this relationship,” Thompson says. “When our patients came in for follow-up and we asked how they were doing, many of them said, ‘Great — my migraines are gone.’ So now we do this [closure] on select migraine patients. Not everyone — only patients who fail standard medical therapy or have significant quality-of-life issues.”
McPherson couldn’t find anyone in Australia who was trained in the NobleStitch procedure — and she was wary about having a traditional device permanently implanted — so she flew to Washington several months ago to have Thompson repair her PFO. “Through an online support group, I spoke to a number of his past patients; all praised the procedure, their recovery and even his calming bedside manner,” she says. “After speaking with him on the phone, I was decided.”
Awake during the procedure, she was nervous, but it went smoothly. She recovered rapidly and was back in Melbourne a week later. “Honestly, my fears were largely unfounded,” she says, recalling the experience. “I didn’t feel anything, except at one stage when I felt as if someone was squeezing me around the throat. I told Dr Thompson. He said what I was feeling was just him tugging on my heart strings.”