RECENT ADVANCES IN CARDIAC SURGERY
From Advances in Anesthetic Practice, sponsored by Loma Linda University School of Medicine
Glenn P. Gravlee, MD, Professor and Vice Chair, Department of Anesthesiology, The Ohio State University College
of Medicine and Public Health, Columbus
| Minimally invasive cardiac surgery: goals and objectives include efficacy equal to traditional approach, reduced
complications, shorter hospital stay, faster return to normal activities, improved cosmesis, and increased
market share (for hospital and practitioners)
|
 | Incisional aspects (from most to least invasive): include traditional median sternotomy with traditional cardiopulmonary
bypass (CPB), partial sternotomy, limited thoracotomy, and port-access (off-pump coronary
artery bypass [OPCAB] grafts done strictly with robotics; known as totally endoscopic coronary artery bypass
[TECAB])
|
| Circulatory support aspects: include femoral CPB, intra-aortic balloon pump, left ventricular assist device
(eg, Nimbus pump), and OPCAB (if possible)
|
| Minimally invasive direct coronary artery bypass (MIDCAB) grafts: paramedian transverse thoracotomy approach
(also reported as vertical thoracotomy; requires breaking rib); minimally invasive mitral valve approach
through right thoracotomy (farther off midline); upper half sternotomy (to access ascending aorta
and aortic valve); lower hemi-sternotomy (for most coronary artery bypass graft [CABG] procedures and
possibly atrial septal defect or mitral valve repair; advantages include greater stability of sternum after procedure,
decreased wound infection, and faster recovery time)
|
| Review of retrospective studies (even with less than perfect study design): found no difference in mortality between
on-pump CABG (OnCAB) and OPCAB approaches (also no difference in incidence of myocardial infarction
[MI], renal failure, or atrial fibrillation); even with full median sternotomy, studies of OPCAB
procedures show less blood loss and transfusion, lower frequency of inotropic requirement after bypass (to
address low cardiac output), and lower incidence of cardiac enzyme elevation; further studies show advantages
with OPCAB in length of hospital stay, length of intubation, and incidence of stroke; some evidence
shows lower graft patency with OPCAB; additional studies of OPCAB vs OnCAB report higher-risk patients
in OPCAB group; increase in OPCAB has resulted in greater use of vasopressors, inotropes, epinephrine,
and norepinephrine; longer and more significant periods of hypotension; more ventricular arrhythmias; may
result in increased MI and mortality rates in certain high-risk populations; consider use of intra-aortic balloon
pump
|
| Anesthetic management: anesthetic preconditioning begins on basis of comparison to ischemic preconditioning
(by inducing short periods of myocardial ischemia); found to protect heart against subsequent longer ischemic
interval; clinical use of two 3-min on-and-off cycles or 4-min on and 6-min off cycles shown to decrease enzyme
leakage (question whether shorter periods actually efficacious)
|
| Mechanisms involved in ischemic preconditioning: starts at cell receptor (sarcolemma), then activate G proteins;
critical intermediary, protein kinase C, inhibits potassium adenosine triphosphate (ATP) channels (at
sarcolemma and at mitochondria)
|
| Anesthetic preconditioning: use of anesthetic drugs to induce effects identical or similar to ischemic preconditioning;
one group has shown in animal models that isoflurane at 1 minimum alveolar concentration (MAC)
as good as 4- to 5-min ischemic preconditioning cycle; pharmacologic preconditioning involves nonanesthetic
agent (eg, adenosine, diazoxide) that may be additive to anesthetic or traditional ischemic preconditioning;
no clearly identifiable differences among potent inhalational agents; work by opening potassium
ATP channels (to greater or lesser degree) by release of reactive O2 species and by neutrophil inhibition; unclear
whether effects increase with increasing doses; morphine has proven preconditioning effect, and remifentanil
and propofol likely to have effect; unclear whether intravenous (IV) agents given in clinically useful
doses capable of initiating preconditioning effect; isoflurane known to protect brain and preserve cerebral
electrical activity at lower total cerebral blood flow than halothane or enflurane; evidence that isoflurane
preconditioning reduces cell death in rat cerebellar ischemia model; also induces late preconditioning that
appears to be neuroprotective in neonatal rats (most likely not unique to isoflurane)
|
| Individual studies: De Hert studies showed halogenated agents associated with less troponin release, greater
preload-recruited contractility, higher cardiac index and mean arterial pressure immediately after CPB, and
less frequent need for inotropic agents; additional study found sevoflurane and desflurane produced less
troponin release, less inotropic use, and shorter intensive care and lengths of hospital stay (but most European
countries experiencing less pressure to get patients out of hospital early); before bypass, increase preload
and measure contractility (increases regardless of anesthetic used); after bypass, contractility increases
with use of inhalational agents, but decreases with use of IV agents; statistically significant reduction in inotropic
support with inhalational agents but not with IV agents (trend seen in vasoconstrictive therapy);
study of remifentanil vs traditional ischemic preconditioning in rat heart found dose-related reduction in infarct
size with remifentanil comparable to that seen with ischemic preconditioning
|
| Managing patient for CABG: maximum myocardial protection by inhalational agents more effective with
OPCAB than with OnCAB (lacks cross-clamp cardioplegic protection induced by OnCAB); however, even
without protection and without using inhalational agents, lesser enzyme release occurs with OPCAB approach;
potent inhalational agents advisable for CABG, particularly with OPCAB; almost certain that doses
as low as 0.5 MAC effective; opioids may be advisable as well (additive effect possible; morphine has most
support)
|
| Neuraxial techniques: Scott—looked at 420 CABG patients undergoing CPB; patients randomly assigned to
either thoracic epidural and general anesthesia or general anesthesia alone; found decreased supraventricular
arrhythmia, improved vital capacity, better pain scores, earlier extubation times, reduced incidence of
lower respiratory tract infections, reduced confusion, and reduced rate of renal failure; β-blockers not given
routinely to either group (standard of care in CABG unless some compelling contraindication; most at least
initiate β-blockers in early postoperative period); pulmonary infection probably relates more to early extubation
than any other outcome; Liu—looked at 15 trials containing ≈1200 patients; found no effect on mortality
or MI from central neuraxial techniques for coronary bypass; dysrhythmia effect comparable to that
expected for β-adrenergic blockers (not used in these studies); tracheal extubation times comparably
achievable with general anesthesia; also looked at intrathecal analgesia as alternative and found 17 trials
with ≈700 patients; morphine used predominantly; did not influence mortality, MI, dysrhythmia, nausea
and vomiting, or extubation time; decreased systemic morphine use, decreased pain scores, and increased
incidence of pruritus; incidence of epidural hematoma remains unknown (>7000 CPB cases reported
worldwide); risk ranges between 1 in 1500 to 1 in 150,000; controversy about low-heparin technique (eg,
OPCAB; major vascular technique) compared to higher heparin technique (eg, OnCAB); relative risks not
yet defined; epidural catheter—in speaker’s practice, many patients hospitalized night before surgery on
heparin infusions; substantially diminishes enthusiasm for placing epidural catheter; published studies now
looking at awake CABG procedures; epidural catheter use in CABG surgery “not totally irrational, but
hard to argue that it’s essential”; OPCAB appears more logical than OnCAB; epidural catheter combined
with general anesthesia approach vs awake CABG appeals more to speaker; selective use may be appropriate
(eg, postoperative refractory ischemia, high pulmonary risk, opioid dependency)
|
| Cardiac surgery in transition: advancements in cardiac care include increasing stent capabilities (eg, antibiotic-
eluting stents; increasing stent longevity), percutaneous mitral valve rings, and decreasing incidence of early
ischemic heart disease; best possible outcome of long-term patency with CABG, particularly with internal
mammary artery graft to left anterior descending artery; increasingly less invasive options (eg, robotics; OPCAB);
sutureless techniques possible (eg, saphenous vein anastomoses with staple gun); distal techniques
with magnetics; increased evidence that transmyocardial laser revascularization more effective in selected
situations than other revascularization options; shortage of transplantable hearts and increase in availability
of ventricular-assist devices, totally artificial hearts, and ventricular remodeling; off-pump surgical approaches
to CABG and valves (increased need for combined procedures); maze and mini-maze procedures
for atrial fibrillation (favor surgical approach); some types of lesions not amenable to stenting; study suggests
as many coronary procedures in 2008 as occurred in 2003 (although difference in types of surgical procedures
performed); additional studies show that what surgeons are doing has some merit
|
| Decreased volume: number of institutions with open-heart surgery programs continues to increase; linked to
repeal of certificate-of-need process in certain states; in Pennsylvania, repeal resulted in increase in cardiac
surgical programs (but number of cardiac surgical programs with smaller volumes increased); suggested
standards from one patient group include 1) full-time, board-certified intensive care personnel and 2) limit
CABG to hospital with annual CABG volume >450 cases
|
| Increased volume: increases seen in congestive heart failure procedures; may be some benefit to certain types
of surgical or nonsurgical interventions; in ventricular restoration procedure, surgeon opens area known to
be dead, determines margin between dead and living tissue, places bovine pericardial patch (similar to
valve), then closes left ventricle over patch; restores ovoid shape to myocardium; results include improved
New York Heart Association class and improved ejection fraction, typically by 10%; preliminary data suggest
smaller better than larger, “and more importantly, shape matters”; patient receiving “pump run,” but no
new heart; monitor and anesthetize accordingly; use most invasive monitors (eg, transesophageal echocardiography
[TEE]; wall motion comparison); often requires simultaneous mitral valve repair (often Alfieri
stitch done from below to shrink mitral valve annulus or traditional mitral valve ring); air evacuation important
|
| Future: Coapsys mitral repair device (reproduces Alfieri stitch technique without opening heart); CorCap cardiac
support device; CABG numbers shrinking, but may have reached plateau; pressure to keep numbers high
to ensure best outcomes; eventually, some cardiac surgical centers will close (move back to regionalization of
cardiac surgery); emerging cardiac catheterization laboratory and electrophysiology (EP) laboratory procedures
may require general anesthesia or deep sedation for best results; TEE required for some procedures, and
anesthesia provider necessary to provide general anesthesia
|
Educational Objectives
| The goal of this program is to educate the listener about recent advances in cardiac surgery and the anesthetic
implications. After hearing and assimilating this program, the participant will be better able to:
|
| 1. Discuss important issues associated with minimally invasive cardiac surgery.
|
| 2. Review anesthetic techniques and monitoring used for minimally invasive cardiac surgery.
|
| 3. Explain the basic principles of anesthetic preconditioning.
|
| 4. Describe various neuraxial techniques for coronary artery bypass graft procedures.
|
| 5. Summarize current and future issues associated with cardiac surgery for the surgeon and the anesthesia
provider.
|
Discussed on This Program
Adenosine [Adenocard, Adenoscan]
Desflurane [Suprane]
Diazoxide [Hyperstat IV, Proglycem]
Enflurane [Ethrane]
Epinephrine (several trade names)
Halothane [Fluothane]
Heparin sodium injection
Isoflurane [Forane]
Midazolam HCl [Versed]
Morphine sulfate (several trade names)
Nitric oxide [INOmax]
Norepinephrine bitartrate (levarterenol) [Levophed]
Pancuronium bromide [Pavulon]
Propofol [Diprivan]
Remifentanil HCl [Ultiva]
Sevoflurane [Ultane]
Suggested Reading
De Hert SG et al: Cardioprotective properties of sevoflurane in patients undergoing coronary surgery with cardiopulmonary
bypass are related to the modalities of its administration. Anesthesiology 101:299, 2004; De Hert
SG et al: Choice of primary anesthetic regimen can influence intensive care unit length of stay after coronary
surgery with cardiopulmonary bypass. Anesthesiology 101:9, 2004; De Hert SG et al: Effects of propofol, desflurane,
and sevoflurane on recovery of myocardial function after coronary surgery in elderly high-risk patients.
Anesthesiology 99:314, 2003; De Hert SG et al: Sevoflurane but not propofol preserves myocardial function in
coronary surgery patients. Anesthesiology 97:42, 2002; Falk V et al: Total endoscopic computer enhanced coronary
artery bypass grafting. Eur J Cardiothorac Surg 17:38, 2000; Fischer SS et al: Symmetry aortic connector
devices and acute renal injury: a comparison of renal dysfunction after three different aortocoronary bypass surgery
techniques. Anesth Analg 102:25, 2006; Khan NE et al: A randomized comparison of off-pump and on-
pump multivessel coronary-artery bypass surgery. N Engl J Med 350:21, 2004; Liu J et al: Minimally invasive
aortic valve replacement (AVR) compared to standard AVR. Eur J Cardiothorac Surg 16 Suppl 2:S80, 1999; Liu
SS et al: Effects of perioperative central neuraxial analgesia on outcome after coronary artery bypass surgery: a
meta-analysis. Anesthesiology 101:153, 2004; Loulmet D et al: Endoscopic coronary artery bypass grafting with
the aid of robotic assisted instruments. J Thorac Cardiovasc Surg 118:4, 1999; MacGillivray TE et al: Patency
and the pump--the risks and benefits of off-pump CABG. N Engl J Med 350:3, 2004; Peterson ED et al: Off-
pump bypass surgery--ready for the big dance? JAMA 291:1897, 2004; Piriou V et al: Pharmacological preconditioning:
comparison of desflurane, sevoflurane, isoflurane and halothane in rabbit myocardium. Br J Anaesth
89:486, 2002; Puskas JD et al: Off-pump vs conventional coronary artery bypass grafting: early and 1-year graft
patency, cost, and quality-of-life outcomes: a randomized trial. JAMA 291:1841, 2004; Scott NB et al: A prospective
randomized study of the potential benefits of thoracic epidural anesthesia and analgesia in patients undergoing
coronary artery bypass grafting. Anesth Analg 93:528, 2001; Zhang Y et al: Remifentanil
preconditioning protects against ischemic injury in the intact rat heart. Anesthesiology 101:918, 2004.
Faculty Disclosure
In adherence to ACCME guidelines, the Audio-Digest Foundation requests all lecturers to disclose any significant
financial relationship with the manufacturer or provider of any commercial product or service discussed.
The following has been disclosed: Dr. Gravlee is an investigator for The Medicines Company.
Dr. Gravlee was recorded at Advances in Anesthetic Practice, presented February 19-23, 2005, by Loma Linda
University School of Medicine and held in Rancho Mirage, California. The Audio-Digest Foundation thanks
Dr. Gravlee and the sponsor for their cooperation in the production of this program.
|
