Sep
22

Aortic Valve Replacement for severe AS

By

David Avitar ArrowheadThe cardiac surgery rotation here at the County hospital has been a tremendous experience for me. This is the first of my seniorĀ rotations and this has been a great start of our second year clinical. Getting up at 4:00 in the morning has never been better. You may ask why such an early wake up. My only reply has got to be that this is when the plump juicy worms are out for easy pickings. Seriously, the cardiac surgery room requires an extensive set up and the early start helps reduce the stress of rushing.

The heart room at LAC-USC opens at 5:30 and by that time I am waiting at the door with all of my equipment gathered in hand, all of the syringes labeled and waiting to be drawn up. Additionally all of the arterial line and double lumen central line / pulmonary catheter equipment are with me. The set up of the syringes and vasoactive drips takes a little while and luckily I have a second year Resident to help me.

This past month I was able to see a few Aortic Valve surgeries with biosynthetic replacement. I have a Slide Show of an aortic prosthetic valve implantation at the photo sharing flickr site. The amazing part of this surgery is the sewing in of the valve to its new home where the old calcified aortic valve used to be. You will note that the aorta is dissected and that the old valve is removed. This procedure requires coronary pulmonary by-pass (CPB) which is an entire topic in itself.

Here is the fun stuff while on CPB it is possible to keep an eye on the surgeons and watch the new valve being sewn into place. Watching the skill of the surgeons and the care that is paid to the individual patient has been a tremendous learning experience.

What I learned today about the induction of cardiac surgery was invaluable. The attending anesthesiologist was able to describe the physiology of stenotic lesions and how to hand ventilate these patients gently with low Pop off pressures; small frequent ventilations during the induction period will keep the mean peak intrathoracic pressures down. The stenotic lesions like aortic stenosis are preload dependant as well as requiring sufficient afterload. Large hand ventilated tidal volumes will increase the intrathoracic pressure and decrease preload lowering cardiac output. This could be a bad thing.

By modifying my hand ventilation technique using less Pop off pressure and smaller tidal volumes with a more rapid rate I was able to achieve lower mean intrathoracic pressures while hand ventilating. I just love this stuff. This was such a great key. I can feel it in my hand now this gentle ventilation technique.

In anesthesia I am continually finding that everything is based on physiology and anatomy. Our techniques must reflect basic understandings of these sciences. This is always more to learn.

Categories : Anesthesia, Student Life

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