Invasive therapies for AS range from balloon aortic valvuloplasty (BAV) to aortic valve replacement (AVR) via sternotomy or the transcatheter approach. In the case of traditional AVR via sternotomy, the valve may be replaced with a mechanical or bioprosthetic valve, the choice largely depending on patient age and ability to tolerate systemic anticoagulation. Over the past decade, transcatheter aortic valve replacement via the transfemoral or transapical approach (TF-TAVR and TA-TAVR, respectively) has been studied, with interest bolstered by the results of the Placement of Aortic Transcatheter Valve Trial (PARTNER trial) 3.
BAV is the least invasive of therapeutic choices once medical management has been exhausted, typically being performed in the cardiac catheterization laboratory. Prior to success with TAVR, BAV was considered a safe and useful option in patients who were deemed too high risk for surgery 4. While BAV may improve hemodynamic parameters, a high recurrence rate of valve stenosis limits the utility of the procedure. Long term survival rates are low and complications are common 5, 6. In the current practice paradigm, BAV may be an appropriate bridge to TAVR in patients who may be suitable candidates but need medical optimization or do not yet meet criteria for a transcatheter procedure 7, 8.
Evolving medical practices, including advances in surgical, anesthetic, and perioperative management techniques, have reduced morbidity and mortality associated with AVR. Overall, mortality is under 3% for all patients, but may be even lower in selected patient populations with minimal comorbidities 9. However, advancing patient age is creating a higher acuity patient population, many of whom are at greater risk for perioperative morbidity and mortality. A recent retrospective review of high risk patients (defined as Society of Thoracic Surgeons predicted risk of mortality of 10% or greater) undergoing isolated, primary AVR, observed an in-hospital mortality rate of 16.4% 10. The same study found a postoperative stroke rate of 4.4%, heart block 5%, multisystem organ failure 6.9%, pneumonia 7.5%, and dialysis 8.2%.
It is clear that traditional AVR carries considerable risk in patients with major comorbidities. In fact, 30–40% of patients with severe AS never undergo surgery due to coexisting medical conditions, heart failure, or physician and/or patient preference 9. Patients deemed too sick, or inoperable, are increasingly becoming candidates for TAVR, either by the transfemoral or transapical approach.
The postoperative period after cardiac surgery may include pain and mental status changes, hemodynamic instability, cardiac arrhythmias, pulmonary edema and respiratory failure, renal failure, and bleeding and coagulopathy. Advances in perioperative and surgical techniques have led to many patients being “fast-tracked”, with rapid extubation and ICU lengths of stay often less than 24 hours. However, as the patient population has become more elderly, morbidity has increased 11 and postoperative intensive care unit (ICU) management has become more complex. In the study previously described of high risk patients undergoing primary AVR, the median ICU length of stay was 3 days 10.
TAVR is less invasive than traditional AVR – no sternotomy is performed, cardiopulmonary bypass (CPB) is not necessary, and patients may be extubated in the operating room (OR). Despite its less invasive nature, over the past few years as the number of TAVRs have increased, a unique set of postoperative events and complications have been identified. While some ICU management issues are shared with patients undergoing traditional AVR, TAVR patients are predisposed to ICU concerns that the intensivist needs to recognize and manage appropriately.