Valley Heart & Vascular Institute - Operative Results and Safety
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Operative Results and Safety

Historically, thoracic aneurysm surgery has been amongst the most risky cardiac surgical procedures performed in the world. With evolution of the surgical techniques and especially advances in neuro (brain) protection, thoracic aneurysm surgery has become much safer. In large volume centers such as ours, elective aneurysm procedural results have changed this reputation. At Valley, elective thoracic aneurysm surgery is a very safe procedure: over 99% survival and no strokes in over 170 elective operations since 2006. We performed 60 aneurysm procedures in 2010 alone, and as our surgical volume has grown, we have been able to hone our techniques to maintain this level of quality.

There are multiple reasons why aneurysm surgery here has become so safe. First, the sheer volume of surgery we are doing places us amongst the busiest aneurysm centers in the nation, and we do more aneurysm procedures than many much larger academic institutions. Our team approach to the procedures, combining surgeon, anesthesia, perfusionist (professionals who manage the heart-lung machine), and nursing expertise had led to a repetitive process with a focus on safety. Most patients who undergo our most complex aneurysm procedures are in the ICU for only a single night, and the large majority is able to be discharged from the hospital on day 4 or 5 after surgery.

From a technical perspective, we use the most sophisticated strategies available to protect the brain and the heart itself during surgery. Specifically, for surgeries that require replacement of part of the aortic arch (very common), many institutions still simply cool the patient (using the heart-lung machine) to 18 degrees C, pack the head in ice, and sew to the opened aortic arch as fast as they can. This historical approach is called 'circulatory arrest'. We utilize a more modern strategy, one that has been associated with the best neurologic outcomes (fewest strokes and cognitive issues after surgery), called 'regional antegrade cerebral perfusion'. Typically, this is done by making a separate incision below the right collarbone and sewing a small polyester tube graft onto an artery called the axillary artery. During the period of time that the aortic arch needs to be open (for suturing the aneurysm replacement graft), blood flow from the heart lung machine is delivered to the brain through the axillary artery (which is temporarily clamped at its base), while blood flow is not provided to the lower body at all. Using this technique, the patients do not need to be cooled as dramatically (usually to 28 degrees C), which has positive implications for how long surgery takes as well as how well the blood will clot after surgery, impacting blood loss and blood product utilization. Colder temperatures lead to thinner blood in general. Thankfully, the lower body and organs (including kidneys and liver) seem to tolerate no blood flow for limited periods of time at a temperature of 28 degrees C.

Over the past year, we have been taking 'regional antegrade cerebral perfusion' one step further. Instead of making a separate incision below the right clavicle, we have been sewing a graft onto a large branch that arises from the aortic arch itself, called the innominate artery. This avoids some pitfalls associated with axillary artery perfusion: the axillary artery can be difficult to access and is often intimately involved with an important nest of nerves called the brachial plexus. Rarely, some of these nerves that control the right arm can be damaged as part of the surgical dissection required to gain access to the axillary artery. In our experience, sometimes the patients can lose blood off of the surgical field with an axillary approach. By perfusing the innominate artery centrally within the main incision, any shed blood is siphoned back into the heart-lung machine and returned to the patient. Finally, because the innominate is a larger artery than the axillary, our perfusionists report less resistance to blood flow from the heart-lung machine, and we also avoid a scenario where the right arm is 'hyper-perfused' during surgery: more blood pressure and flow to the right arm which could lead to some swelling after surgery. Our neurologic outcomes using this approach have been superb, and we plan on reporting on this experience in the near future, as we seem to be one of only very few places in the world to use this more advanced strategy.

Lately it has become quite common in our program to not have to transfuse blood or blood products during or after elective aneurysm surgery. This is almost unheard of amongst active programs. This probably has to do with the fact that we are able to cool to less dramatic target temperatures, innominate artery cannulation, as well as our surgical techniques that utilize double layer suturing when possible. Avoiding transfusion is known to have both long and short term health benefits.

Another aspect of our program that has contributed to excellent results is our 'heart protection' strategy. Certain aneurysm procedures can take a long time, up to 3 hours spent on the heart-lung machine. The heart itself is put on a special 'life-support' system that keeps it in a low-energy state, and essentially anesthetized. This is accomplished by perfusing the heart with cold (4 degree C) blood that is enriched with high levels of potassium, a standard solution called 'blood cardioplegia'. What we do differently is that we continuously deliver this solution to the heart throughout surgery, as opposed to intermittently (the standard approach). In addition, we are vigilant about protecting the right side of the heart, which has to be done independently of typical intermittent or continuous strategies, which largely protect the left side of the heart only. The advantages to these techniques are that the heart can perform beautifully despite having been arrested (stopped with cardioplegia) for 2 hours or more. If the heart is not itself protected aggressively, it may not function normally for several hours after surgery, leading to the need for specific medication infusions, or transfusions to support the circulatory system.

Many patients with aneurysm are young and relatively healthy. We feel that attention to these details not only minimizes our major complication rates, but also seems to be accelerating our patients' recoveries overall after discharge. Extremely low mortality and stroke rates are part of the reason that pre-emptive surgery for asymptomatic aneurysm can be justified in our program.

For more information, contact Leanne Scaglione, R.N., MSN, APN-BC, Coordinator for the Thoracic Aneurysm Surveillance Program, at 201-447-8398.

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