Doughty’s Surgery Update
Pulmonic Stenosis is a congenital obstruction in the right heart that restricts the flow of non-oxygenated blood out of the heart, into the pulmonary artery and on to the lungs for oxygenation. The condition leads to an enlarged heart (“hypertrophy”) and eventually failure and sudden death. The degree of obstruction is determined by measuring the pressure gradient on either side of the obstruction using echo-cardiogram. A normal pressure gradient in the area is 4 mmHg (“millimeters of mercury”). A moderate obstruction reads 4-50 mmHg, and is not considered dangerous. A gradient of 50-80 mmHg warrants treatment with medication. At 80 mmHg, surgery is considered.
At nine months, Doughty measured 90 mmHg. At 13 months she measured at 124 mmHg. Monday October 12th, the day before surgery, she measured at 151 mmHg. Obviously, this wasn’t moving in the right direction.
She was 14 months old.
Here’s an abstract of a journal article that describes a procedure similar to the procedure my dog underwent, written by the surgeon who did both. Basically, Dr. Orton pre-positioned a 1 1/2″ by 3″ Gore-Tex patch over the obstructed area and then stopped the flow of blood through her heart (“inflow occlusion”). With blood flow blocked, he made an incision under a gap he left during pre-positioning of the patch, closed the gap and restarted blood flow. Blood flow was stopped for about a minute. From beginning to end, the surgery lasted almost three hours.
“Very smooth,” he said afterward. “Usually it’s a fire drill during occlusion.”
The patch will become the new “wall” of the right ventricle outflow tract. The dog’s tissue will intertwine with the Gore-Tex fabric and eventually cover it altogether. The surgeon did not remove the obstruction; he increased the circumference of the outflow tract, obstruction and all, creating a bigger channel for blood to flow through. A preliminary echo done the day after surgery measured a pressure gradient of 40 mmHg. It was a good result — much better than expected. A second echo two days after surgery showed 36 mmHG. We’ll need to do another echo in December to confirm the result.
Dogs recover from major surgery much quicker than people do. Doughty was out of the hospital the next day, in fact. She looked like hell all shaved and stitched (“Franken Terrier”) and she probably felt that way, but less than 48 hours after surgery, she was already back to fetching and barking at strange noises. They are durable little creatures. We were cleared for the long drive home on Friday October 16th, three days after surgery.