Saturday, October 03, 2009

Calling for Reinforcements

Bluebonnets, dogwoods, and azaleas are just about the only thing I miss about Texas. Good Tex-Mex too --- I do love good fajitas and a cold margarita or two. Now, where I come from there is only one way to make fajitas, and that involves using skirt steak. I don't want to make you cough up your milk, but that means properly prepared steak fajitas are made with grilled marinated strips of a cow's diaphragm.

The human diaphragm, if I may say so, are one of God's neat little tricks. It's a tough, broad sheet of muscle, modest in thickness, that acts both as a barrier between the abdominal and thoracic cavities, but also as a vacuum assist device for breathing. When you take a deep breath, the chest wall and abdominal muscles expand the chest cavity, and the diaphragm moves outward and downward, drawing air into the lungs. It's also a favorite subject for pimping medical students --- what water fowl cross the diaphragm?

  • The thoracic "duck" (duct)
  • The "azygoose" (azygous vein"
  • The "vagoose" (vagus nerve)
  • The "esophagoose" (esophagus)
Each of these structures, as well as the aorta and inferior vena cava, passes through an opening in the diaphragm; occasionally, one of those openings is larger than it should be. The opening through which the esophagus passes, called the esophageal hiatus, is sometimes large enough to cause a few problems, and when it is so it is termed a hiatal hernia. Without getting into too much detail, a hiatal hernia needs to be surgically addressed when we are performing antireflux surgery for GERD or when there is a large paraesophageal hernia.

OK, you say, no biggie. Just put a few stitches in it and close it up! Well, it can't be completely closed, or the esophagus gets tied off in the process. No Big Macs for you! But there is another problem. If you look at the image to the right displaying the undersurface of the diaphragm (from the online version of Gray's Anatomy), you will see a whole bunch of red, and not a lot of white. Compare that to the illustration on the left, which is an oblique view of the abdominal wall; in the mid-portion of the abdomen there is a sea of white.

The white areas represent muscle that is covered by a nice, tough layer of fascia --- that is the stuff we sew together when closing the abdomen, the good stuff that will hold sutures. The red areas represent muscle without much fascial covering, which hold sutures about as well as a cup of water. We have an expression for this --- "sewing flatus to a moonbeam" --- and an expectation that the closure won't hold up well. There is minimal fascia at the hiatus, so as a result, hiatal closures don't tend to hold up well in the long run.

Over the past few years, some enterprising souls have taken note of the good experience we have with augmenting hernia repairs with mesh (usually polypropylene) and have placed mesh overlying the hiatal closure. Initial results have been quite good, with a significant reduction in repair failures. However, I have always been reluctant to consider this option --- we have years of evidence that leaving mesh exposed to the GI tract is in general a bad thing, as it can densely adhere to bowel and even erode into it. And having chip-chip-chipped away at a few Angelchik devices that have eroded into the esophagus, I'm not eager to do the same with material that will create a significant inflammatory response.

Hah! I have been shown to be prescient once again. Mesh complications after prosthetic reinforcement of hiatal closure: a 28-case series is an article published in the June edition of Surgical Endoscopy. The authors cobbled together their collective experiences with mesh complications at the hiatus and published them:
Twenty-six patients underwent laparoscopic and two patients open surgery for large hiatal hernia (n = 28). Twenty-five patients had a concomitant Nissen fundoplication, two a Toupet fundoplication, and one a Watson fundoplication. Mesh types placed were polypropylene (n = 8), polytetrafluoroethylene (PTFE) (n = 12), biological mesh (n = 7), and dual mesh (n = 1). .... Main reoperative findings were intraluminal mesh erosion (n = 17), esophageal stenosis (n = 6), and dense fibrosis (n = 5). Six patients required esophagectomy, two patients had partial gastrectomy, and 1 patient had total gastrectomy. Five patients did not require surgery. In this group one patient had mesh removal by endoscopy. There was no immediate postoperative mortality, however one patient has severe gastroparesis and five patients are dependent on tube feeding. .... There is no apparent relationship between mesh type and configuration with the complications encountered.
Now, I'd like to say a few things about this study. First of all, thank you. Thank you to the authors who published results that call into question a practice that has gradually become a bit more common, calling for some caution and for a multicenter prospective study. Secondly, while the names on the list of authors may not mean much to you, they represent a large cross-section of the most respected surgeons in this field, including the "godfather" of gastroesophageal junction surgery. Two I know personally, and I know that they are extremely honest in their reporting. So this is not a collection of complications from a bunch of fly-by-night yahoos, but folks who do and study these operations extensively --- i.e., when they were doing this, they had good reason to expect it would work, and work well. Lastly, it was interesting to me that certain types of mesh that are specifically touted as being better to use in this area --- PTFE (Gortex) and biological mesh (denatured tissues of a variety of types, which allow ingrowth of natural collagen) were found to have the same risk of complications as old-fashioned polypropylene.

So, what to do? I agree with the authors when they call for a prospective multicenter trial, but it is important to recognize that when this type of complication occurs, it can be pretty devastating for the patient. And I suppose that more surgeons will be a bit reluctant to use mesh for hiatal closure unless there is no alternative, even though we use them extensively (safely) elsewhere.