Seminars in Cardiothoracic and Vascular Anesthesia

Despite considerable advances, coronary artery disease is the leading cause of morbidity and mortality in the Western world. The development of effective therapeutic strategies for protecting the myocardium from ischemia would have major impact on patients with coronary artery disease. It is now accepted that patients with coronary artery disease can experience prolonged regional ischemic dysfunction that does not necessarily arise from irreversible tissue damage, and to some extent, can be reversed by restoration of blood flow. The initial stages of dysfunction are probably caused by chronic stunning that can be reversed after revascularization, resulting in rapid and complete functional recovery. On the other hand, the more advanced stages of dysfunction likely correspond to chronic hibernation. After revascularization, functional recovery will probably be quite delayed and mostly incomplete. Over the past decade, the possibility that an innate mechanism of myocardial protection might be inducible in the human heart has generated considerable excitement. In the last two decades, there was phenomenal growth in the understanding of the mechanism known as ischemic preconditioning that is responsible for the innate myocardial protection. Continued research and progress in this area may soon lead to the availability of preconditioning-mimetic treatments. The current concepts, mechanisms, and potential clinical applications of myocardial hibernation, stunning, and ischemic preconditioning are reviewed.

The number of adults with congenital heart disease surviving into adulthood is increasing. The proportion of adults undergoing revision of a previous repair is increasing in comparison to those that present for a palliative or curative operation. At the Toronto Congenital Cardiac Centre for Adults, 528 patients underwent cardiac surgery between January 1, 1992 and December 31, 2001. The anesthetic management of the surgical correction of simple and complex congenital heart lesions includes general physiologic considerations such as dysrhythmias, hypoxemia, polycythemia, and pulmonary hypertension. Palliative shunts from early childhood have anatomical and physiologic implications for the adult. Preparation for the operating room and postoperative care are natural extensions of the anesthetic management of the surgical correction of the congenital heart lesions. Anesthetic management of septal lesions in the interventional suite and operating room is discussed. Complex lesions such as tetralogy of Fallot, transposition of the great arteries, Glenn anastomosis, and the Fontan operation are reviewed. The anesthetic management of these patients is rewarding but impossible without an integrated team approach involving cardiologists, surgeons, perfusionists, and nursing staff.

This review covers the classification of congenital heart diseases, and the preoperative assessment, monitoring, anesthetic considerations, and management in the pediatric population with congenital heart disease. It does not present “recipes” for individual cardiac defects. The pathophysiology is presented as it relates to principles of management, patient assessment, selection, and application of an anesthetic regimen to specific cardiac lesions and procedures. Familiarity with the child's pathophysiology, preoperative preparation, choice of monitors, induction, maintenance, emergence from anesthesia, and plans for the postoperative period should avoid major problems in anesthetic management.

Pregnancy and heart disease present a unique challenge to the anesthesiologist. Pregnancy results in physiological changes to the parturient's cardiovascular system that can unmask or worsen underlying heart disease. To avoid untoward complications resulting in significant maternal and/or fetal morbidity or mortality, the anesthesiologist must be knowledgeable about the progression of heart disease during pregnancy. Discussed are the pathophysiology, clinical presentation, and anesthetic management of valvular, congenital, vascular, and ischemic heart disease, and cardiomyopathy in pregnancy.

Perioperative bleeding in cardiac surgery is related to both surgical trauma of blood vessels and defects in the hemostatic mechanism caused, in part, by cardiopulmonary bypass. Blood transfusion therefore remains a significant risk of cardiac surgery with important health and economic consequences. Blood conservation strategies for cardiac surgery have advanced over the years and the following discussion will focus on the current practices at Toronto General Hospital.

Over the past few decades, major surgical procedures involving the thorax have become commonplace at most larger medical facilities. Advances in perioperative care have allowed surgeons to perform increasingly complex procedures. These procedures are being performed on more seriously ill patients who are at increased risk for significant complications. Recent advances should help the anesthesiologist avoid some of the pitfalls in managing these complex patients. Preoperative assessment aids in the identification of patients at highest risk for intraoperative and postoperative events. Particular attention is given to myasthenia gravis, as thymectomy is among the most common surgical procedures that are performed in these patients. Aggressive pain control techniques, including neuraxial opioids and patient-controlled analgesia, where appropriate, not only improve patient comfort but can improve postoperative pulmonary function. Advances in techniques for providing one-lung ventilation allow the anesthesiologist more options to individualize management for each clinical scenario. Careful fluid management may help to minimize the risk of postoperative pulmonary complications. A basic understanding of video-assisted thoracic surgery should help the anesthesiologist provide optimal surgical conditions and perioperative care. Recent advances demand a greater role for the anesthesiologist if the best outcomes are to be achieved in patients undergoing thoracic procedures.

Although endovascular surgery for aortic aneurysms can be traced to the 19th century, open surgery has dominated during the past 50 years. Indeed, open repair of aneurysms has been one of the most successful developments in vascular surgery. Despite improvements in mortality rates, open repair remains a major operation often undertaken in patients with significant comorbidities. Starting from basic research dating back several decades, the 1990s were noted for very active clinical development of endovascular abdominal aortic repair in an attempt to provide an alternative to open repair, especially for high-risk patients. Early successes with decreased intensive care unit and hospital stays were tempered by technical issues and the “endoleak,” the term given to an incomplete exclusion of the aneurysm from the circulation. This potential for rupture, despite treatment, was cause for concern. The need for long-term surveillance and secondary procedures, if not conversion to open repair, further compounded these issues. Despite these concerns, progress continued, and by the end of 2002, the Food and Drug Administration had approved three devices for marketing. Although surgeons are faced with increasingly complex issues related to endovascular repair, anesthesiologists have found their management of this procedure to be simpler in many ways. The smaller incisions and improved hemodynamic stability have led to a variety of anesthetics being tried, including monitored anesthesia care. Anesthesiologists continue to explore a number of opportunities to improve patient outcome in these procedures. These include selection of the most optimal anesthetic, the most appropriate perioperative renal protection, and the best preparation for and management of a conversion to an open procedure. Whatever the final role for endovascular surgery in the management of abdominal aortic aneurysms, it is an intellectually stimulating and scientifically promising technique for surgeons, anesthesiologists, and the patients they serve.

Since the early 1 990s, endovascular surgery has provided another treatment option for the management of abdominal aortic aneurysms. Its shorter postoperative recovery time, absence of an abdominal incision, and avoidance of aortic cross-clamping gives endovascular abdominal aortic aneurysm repair its appeal. New vascular grafts are being developed that may expand the number of eligible candidates. This less-invasive form of abdominal aortic aneurysm repair still provides the anesthesiologist with several challenges. The procedure has been performed under general anesthesia, regional anesthesia, and local anesthesia with monitored anesthesia care. The potential benefits of one anesthetic type over another for endovascular abdominal aortic aneurysm repair have not yet been fully explored. Several intraoperative complications, including acute aortic rupture and misdeployment of the stent graft, can necessitate conversion to an open laparotomy. Endovascular repair in the short term compares favorably to open surgical repair with a reduction in morbidity, blood loss, and hospital stay. Still, endovascular abdominal aortic aneurysm repair is a relatively new corrective modality, and long-term controlled trials comparing it with open repair have not yet been reported. As more research into the technique is performed, new strategies for endovascular abdominal aortic aneurysm repair may further increase the options available to patients.