CoreValve

Medicine is moving towards minimally invasive surgery, and cardiac surgery is no exception. The VA participates in a national trial evaluating a percutaneous aortic valve replacement with the CoreValve system. Along with the Sapien valve, these two devices are aortic valve replacements deployed through the femoral artery, or less commonly, through the aorta. Patients qualify for these procedures if they are too high risk for standard open-heart aortic valve replacement with cardiopulmonary bypass. The trials with these devices, however, are quite impressive. Although there is a significant risk of stroke, outcomes with these valves are not bad, especially considering how sick the patients who receive them are.

We coordinate the case with cardiac surgery, cardiology, and the cardiac catheterization lab. After placing an IV and an arterial line, we induce anesthesia. Because these patients all have severe or critical aortic stenosis, this is an extremely high risk moment. Unlike our standard cases where we use high doses of fentanyl and midazolam, our goal is to wake the patient and extubate immediately after the procedure so we have to rely on etomidate (and rarely propofol) based inductions. I mention this moment blog after blog because I think it's underrecognized how dangerous general anesthesia can be for these patients with such advanced cardiac disease and even our physician colleagues rarely realize that we employ all our knowledge of cardiac physiology, disease states, pharmacology, pharmacokinetics, and technical ability in these five minutes around intubation. After securing the airway, we place a central line for vasoactive medications and a trans.

During the entire procedure, the perfusionist is on standby in case we need to crash onto cardiopulmonary bypass; luckily, this is a very rare event. The surgeons do a cut-down to the femoral vessels in the leg; if the femoral artery is too small to accommodate the device, they have to do a mini-thoracotomy in the chest and cannulate the aorta (in this case, we have to isolate the lung with a double-lumen endotracheal tube). The cardiologists put a femoral arterial line and temporary pacemaker into the heart. Then, they guide the replacement aortic valve through a large-bore sheath retrograde into the heart. They position the valve with both fluoroscopy and echocardiography. First, the cardiologists do a valvuloplasty to open up the diseased valve, followed by deploying the artificial valve. In order to do this, they pace the heart incredibly rapidly. They don't want the heart squeezing when the valve is deployed because this can dislodge the valve. By pacing at around 200 beats per minute, the ejection fraction is minimal; though this is transient, the changes in blood pressure are quite alarming. After the new artificial valve is placed - in a way blindly since it is only guided by fluoroscopy and echocardiography - we look on echo to look for perivalvular leak. If the valve looks like it's seated well, they surgeons close up the femoral incisions and we prepare to wake up and extubate the patient. Surprisingly, they rarely need high doses of vasoactive drips. Occasionally we have to place a temporary pacemaker because the CoreValve can cause heart block. The whole procedure takes a couple hours and patients can be awake, talking, and ready to eat several hours afterwards. Its quite impressive as recovery seems so much easier with the percutaneous approach rather than the open approach.