Monday, October 10, 2016

9/28/16

Despite being quite a standard day at the HVI, I got to see (a part of) a case that I haven't seen in a while-- an open-heart mitral valve replacement. A mitral replacement is performed to counter calcification or other interruptions to blood flow in the mitral valve, and replaces the defective valve with a prosthetic or biological one. This is a fun surgery to watch, as its procedure doesn't leave much to the imagination. First, the sternum is split with a saw in an incision 3-4 inches in length, and underlying tissues are then bisected length-wise to get a decent view of the heart. Cardioplegia is administered to slow the heart and prepare for bypass. The cardiopulmonary bypass machine is used to pump blood throughout the body in place of the heart, and reoxygenate it without the use of the lungs; it does this by cannulating the vena cava or right atrium to draw out deoxygenated blood, oxygenating it outside of the body, and then feeding it back into the ascending aorta. This allows for the attending surgeons to operate on a still heart and chest, which is pretty useful. Going further, an incision is made in the heart's left atrium, exposing the mitral valve. After removing the diseased valve leaflets and annular tissue, there is a long preparation for the new valve's insertion into the mitral space. I like to call it "scaffolding": a ring of sutures is sewn into the tissue, and then used to lower in the replacement valve. I'll include a picture of this (a).

Arriving at the tail end of the surgery, I missed all of this, and saw more of the cleanup process than anything else. The patient soon finished being weaned off of the bypass machine, and the final sutures were performed in the chest cavity. Shortly after, chest tubes were inserted into the mediastinal cavity to help with post-op fluid drainage. In the days following an invasive surgical procedure, a mixture of body fluids will leak from the damage done to the tissue inside the chest-- the chest tubes provide a place for that fluid to drain to, preventing against nasty infections and other complications. Valuable, but a bit gross nonetheless. One might also wonder how the sternum is pieced back together after being sawed in half, which yields a more complicated answer than one would expect. Well, metal wires are looped through the tissues directly adjacent to the center of the sternum, then cut before another loop is made. This results in multiple horizontal lines of wire, running under both sides of the sternum and out through the left and right breast.These lines are then crossed and twisted until the two pieces of the sternum meet. After this, the excess pieces are clipped, and the performing surgeon tightens the twisted wires as they see fit. The wire-ties are then pressed down and into the surrounding tissue. It's almost like heavy duty suturing, but is a bit hard to explain without a picture-- see below (b). A standard sealing/suture procedure reattaches  the tissue above the sternal plate back together, ending the surgery. 

The solicitation letter for the next phases of the Heartwell Project has been finished, but Dr. Nguyen has been rather busy recently, and hasn't had a chance to give any input. We aim to use his minivalve web domain to host information about fundraising, and use as an ancillary viewing platform to our YouTube channel if/when the videos are ready.


Ex. A.
Ex. B.








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