Fiona M. Clements

The utility of transesophageal echocardiography and Doppler color flow imaging in patients undergoing cardiac valve surgery

To assess the value of intraoperative transesophageal echocardiography during cardiac valve surgery, 154 consecutive patients who had a valve operation in conjunction with pre- and postcardiopulmonary bypass transesophageal imaging were studied. Prebypass imaging yielded unsuspected findings that either assisted or changed the planned operation in 29 (19%) of the 154 patients. Imaging immediately after bypass revealed unsatisfactory operative results that necessitated immediate further surgery in 10 (6%) of the 154 patients. Postbypass left ventricular dysfunction, prompting administration of inotropic agents, was identified in 13 patients (8%). Transesophageal echocardiography proved most useful when both two-dimensional and Doppler color flow imaging were employed in patients undergoing a mitral valve operation, where surgical decisions based on echocardiographic results were made in 26 (41%) of 64 cases. Postbypass echocardiographic findings identified patients at risk for an adverse postoperative outcome. Of 123 patients whose postbypass valve function was judged to be satisfactory, 18 (15%) had a major postoperative complication and 6 (5%) died, whereas of 7 patients with moderate residual valve dysfunction, 6 (86%) had a postoperative complication and 3 (43%) died (p less than 0.05 for both). Likewise, of 131 patients with preserved postbypass left ventricular function, 12 (9%) had a major complication and 7 (5%) died, whereas of 23 patients with reduced ventricular function, 17 (73%) had a postoperative complication and 6 (26%) died (p less than 0.05 for both). These data indicate that intraoperative transesophageal echocardiography is useful in formulating the surgical plan, assessing immediate operative results and identifying patients with unsatisfactory results who are at increased risk for postoperative complications.

Silent myocardial ischemia in patients undergoing peripheral vascular surgery: Incidence and association with perioperative cardiac morbidity and mortality * **

Atherosclerosis is a systemic disorder and coronary artery disease is highly prevalent in patients treated for lower-extremity obstructive vascular disease. Myocardial ischemia and infarction represent the most frequent and most clinically important complications of surgical procedures for lower-extremity revascularization. Despite attempts in several areas, no practical, sensitive, and specific method for identifying patients at highest risk for myocardial events postoperatively has been found before now. This study reports observations on a consecutive series of 50 patients who underwent continuous perioperative electrocardiographic monitoring with a microprocessor-based electrocardiographic ischemia monitor. Thirty-eight percent of the patients were found to have episodes of ischemia; most of these episodes were painless and would not otherwise have been recognized. Ischemia was most prominent in the postoperative rather than the preoperative or intraoperative phases. Tachycardia was often associated with ischemia. Significantly more cardiac-related morbidity and deaths occurred in patients who were documented to have silent myocardial ischemia. In fact, no cardiac events occurred in the 31 patients without ischemia (p less than 0.02). This type of ischemia monitoring represents a potential method for segregating patients at high risk for cardiac-related morbidity and death during lower-extremity revascularization.

Mitral valve operation via Port Access versus median sternotomy

OBJECTIVE The advantages and disadvantages of minimally invasive Port Access mitral valve operation have not been defined relative to standard median sternotomy. A study was therefore designed to delineate differences in outcome from mitral operation via Port Access versus sternotomy in comparable patients. METHODS The records of 41 consecutive patients undergoing isolated mitral valve replacement (n = 14) or repair (n = 27) were examined. All operations were performed using cardioplegic arrest through either median sternotomy (n = 20) or a small right anterolateral thoracotomy using an endoaortic clamp and catheter system (Heartport, Redwood City, CA) to arrest and decompress the heart (Port Access, n = 21). RESULTS Both groups were well matched for age, mitral pathology, ejection fraction, and comorbidity. except that Port Access patients were less likely to be female. Three patients had undergone previous cardiac operations. Surgical procedure time was longer for Port Access patients (384+/-80 vs. 263+/-41 min, P < 0.05). Port Access provided significantly smaller incision length (8+/-2 vs. 26+/-2 cm, P < 0.01) and similar or shorter hospital stay (6+/-4 vs. 7+/-3 days). Port Access provided excellent visualization of the mitral valve and subvalvular apparatus, generally better than sternotomy, to allow complex mitral valve repairs. The greatest advantage of Port Access mitral operation was that Port Access patients returned to normal activity more rapidly (4+/-2 vs. 9+/-1 weeks, P = 0.01) than did patients undergoing standard median sternotomy. CONCLUSIONS By avoiding a sternotomy, Port Access mitral valve operation provided a smaller incision and a dramatically more rapid return to normal activity than did median sternotomy. Port Access cardioplegic arrest with the Heartport system allowed visualization of the mitral valve superior to median sternotomy and has become the standard approach at this institution.

Improvement in inducible ischemia during dobutamine stress echocardiography after transmyocardial laser revascularization in patients with refractory angina pectoris.

OBJECTIVES The purpose of this ongoing study is to determine whether transmyocardial laser revascularization (TMLR) can lessen inducible ischemia and improve contractile reserve in patients with refractory angina pectoris. BACKGROUND TMLR is an emerging surgical technique for the treatment of myocardial ischemia and angina pectoris not amenable to conventional percutaneous or surgical revascularization. Objective data documentating a reduction in ischemia during noninvasive stress testing after TMLR are rare. METHODS Fifteen patients with severe coronary artery disease unsuitable for treatment with standard revascularization techniques were studied with dobutamine stress echocardiography (DSE) before TMLR. Of the 12 patients who underwent TMLR, DSE was repeated at 3 months postoperatively in 11 patients and at 6 months in 9 patients. Stress echocardiograms were analyzed for inducible ischemia, with calculation of the wall motion score index (WMSI). Heart rate and dobutamine dose achieved at peak stress were also assessed as indexes of stress tolerance. RESULTS Compared with that before TMLR, wall motion at rest for all myocardial segments did not change significantly after TMLR, although there was a mild improvement in the WMSI of the lased myocardial regions ([mean +/- SD] 1.64 +/- 0.34 after vs. 1.78 +/- 0.34 before TMLR, p < 0.05). Overall WMSI at peak stress improved markedly after TMLR (1.70 +/- 0.30 after vs. 2.06 +/- 0.31 before TMLR, p < 0.002), with the improvement in WMSI limited to the lased segments only (1.47 +/- 0.31 after vs. 2.15 +/- 0.34 before TMLR, p < 0.0004). The improvement in WMSI with stress resulted primarily from a decrease in the percentage of ischemic segments (47% before vs. 23% after TMLR, p < 0.0008), with no change in the percentage of infarcted segments (23% before vs. 26% after TMLR). Heart rate (83 +/- 5 beats/min before vs. 102 +/- 21 beats/min after TMLR, p = 0.01) and dobutamine infusion rate (26 +/- 9 micrograms/kg body weight per min before vs. 34 +/- 9 micrograms/kg per min after TMLR) achieved at peak stress also increased postoperatively, consistent with improved stress tolerance. The reduction in ischemic wall motion abnormalities and improved stress tolerance persisted at 6 months, without evidence of further improvement or deterioration of function over time. CONCLUSIONS TMLR performed in patients with refractory angina pectoris reduces ischemic wall motion abnormalities and improves stress-induced tolerance during dobutamine echocardiography. These beneficial effects persist up to 6 months postoperatively.

Perioperative evaluation of regional wall motion by transesophageal two-dimensional echocardiography.

With the introduction of transesophageal two-dimensional echocardiography into the operating room the subject of regional left ventricular (LV) wall motion presents itself to the clinical anesthesiologist. Overwhelming evidence of the sensitivity of regional wall motion as a marker of regional myocardial perfusion suggests that it will find a place for the monitoring of patients at risk for ischemia. In this review, we define regional wall motion, normal and abnormal, and examine its relationship to regional myocardial perfusion. The practical aspects of recognizing, describing, and treating regional wall motion abnormalities will be addressed, with emphasis on transesophageal two-dimensional echocardiographic techniques. The development of transesophageal imaging techniques has taken place only during the past 10 yr. Frazin and co-workers in 1976 reported the use of an M-mode esophageal transducer for patients in whom conventional imaging techniques failed (1). Generally, transthoracic images are technically poor when excessive adipose or lung tissue lies between the external transducer and the heart. Thus, the esophagus provided better access to the heart. Matsumoto and co-workers employed esophageal transducers in subjects performing supine bicycle exercise and also in anesthetized patients (2,3). The incorporation of the transducer into a flexible gastroscope from which the fiber optics had been removed permitted the operator to direct the ultrasound beam in multiple planes from any position within the esophagus. With the development of miniature phased array transducers, excellent two-dimensional imaging became feasible from the esophagus. Schluter and co-workers reported their use of such a transducer in 1982 (4), and it is this type of esophageal transducer that has been used by most investigators and that has produced the images presented in this review.

Cerebral physiologic effects of burst suppression doses of propofol during nonpulsatile cardiopulmonary bypass

Central nervous system (CNS) complications are common after cardiac surgery.Death due to cardiac causes has decreased, but the number of deaths due to CNS injury has increased. As a first stage in the evaluation of its cerebral protection potential, we evaluated the cerebral physiologic effects of burst suppression doses of propofol during nonpulsatile cardiopulmonary bypass. Thirty patients without history of cerebral vascular disease were randomized to two study groups: control group (n = 15) who received sufentanil and vecuronium, or propofol group (n = 15) who received the control anesthetic and propofol infused to maintain electroencephalogram (EEG) burst suppression. Catheters were placed in the radial artery and right jugular bulb for sampling of systemic arterial and jugular bulb venous blood.133 Xe clearance was used to determine cerebral blood flow (CBF) at the start of normothermic bypass, during stable hypothermia, and when rewarmed to 35-37 degrees C nasopharyngeal temperature. Pharmacologic burst suppression with propofol produced a statistically significant reduction in CBF, cerebral oxygen delivery (DO2), and cerebral metabolic rate (CMRO2) at each measurement interval (P < 0.05 vs control). Cerebral arterial venous oxygen difference (C(a-V)O2), and jugular bulb venous oxygen saturation (SJVO2) were not statistically different between groups, indicating maintenance of cerebral metabolic autoregulation (coupling). The reduction in CBF and CMRO2, prominent during the normothermic phases of cardiopulmonary bypass (CPB), indicates a potential for propofol to reduce cerebral exposure to the embolic load during CPB. (Anesth Analg 1995;81:452-7)

Right and left ventricular performance during and after abdominal aortic aneurysm repair.

To evaluate the effect of aortic occlusion and limb reperfusion on global and regional function of the right and left ventricle during infrarenal abdominal aortic aneurysm repair, 23 patients underwent five intraoperative first-pass radionuclide angiocardiograms: 1) before the skin incision, 2) at aortic cross-clamp, 3) 20 minutes after aortic occlusion, 4) at unclamping, and 5) after skin closure. A subset of twelve patients had simultaneous transesophageal echocardiography to evaluate left ventricular wall stress. Parameters measured included the electrocardiogram (ECG), heart rate, blood pressure, pulmonary artery pressure, the cardiac output, the left and right ventricular ejection fractions, left ventricular volumes, and left ventricular wall stress. Significant changes (p < 0.01) were observed at aortic clamping in the left ventricular ejection fraction (from 0.56 to 0.48), end-diastolic volume (from 171 to 225 ml), end-systolic volume (from 85 to 127 ml), mean blood pressure (from 82 to 91 mmHg), and meridional end-systolic wall stress (from 53 to 67 103 dyne/cm2). Once the clamp was removed, significant variations were seen in the left ventricular ejection fraction (from 0.51 to 0.58), enddiastolic volume (from 205 to 187 ml), end-systolic volume (from 105 to 94 ml), mean blood pressure (from 84 to 69 mmHg), and meridional end-systolic wall stress (from 67 to 46 103 dyne/ cm2). No differences were observed between the two aortic occlusion studies, and the baseline level of function was recovered in all parameters during the last study. These data quantify the changes in heart function that occur during abdominal aortic aneurysm operation and demonstrate that the majority of the adaptations that occurred were due to a variation in afterload.

Coronary Sinus Catheterization Made Easy for Port-Access Minimally Invasive Cardiac Surgery

A MONG MANY evolving techniques for performing cardiac surgery through small incisions, the Port-Access system (Heartport Inc, Redwood City, CA) provides the convenience of cardiopulmonary bypass and hypothermic cardiac arrest without requiting sternotomy. The technique allows for administration of antegrade and, where indicated, retrograde cardioplegia, without the direct access to the heart that is conventionally enjoyed by the surgeon. For retrograde cardioplegia delivery, the anesthesiologist inserts a cardioplegia catheter into the CS from the internal jugular vein. Most anesthesiologists are unfamiliar with this new skill. A simple method for successful placement of a CS catheter using TEE and fluoroscopy is described in this article.

Antiphospholipid syndrome and cardiac surgery: management of anticoagulation in two patients.

Antiphospholipid (APL) syndrome characterizes a clinical condition of arterial and venous thromboses associated with phospholipid-directed autoantibodies (1). APL syndrome occurs in 2% of the general population (2); however, one study demonstrated that 7.1% of hospitalized patients tested positive for at least one of three anticardiolipin antibody idiotypes (3). Several reports suggest that patients with APL syndrome are at increased risk of coronary artery disease and/or valvular pathology (4–5). In addition, APL antibodies often inhibit phospholipid-dependent coagulation in vitro and interfere with laboratory testing of hemostasis. The management of anticoagulation during cardiopulmonary bypass (CPB) can therefore be quite challenging in these patients; our approach in two recent cases is described.

Intraoperative Transesophageal Color Flow Mapping: Initial Experience

Transesophageal Doppler color flow mapping (TEDCFM) is a new ultrasound modality now being developed. It provides a convenient, noninvasive way to image cardiac anatomy and intracardiac blood flow that is applicable to intraoperative use. We describe its use in one normal subject and seven cardiac surgical patients. Blood flow characteristics as visualized by TEDCFM are described for these patients. Transesophageal Doppler color flow mapping provided specific information about the presence, site, and severity of mitral regurgitation, aortic regurgitation, and interatrial shunting. Paravalvular leak was detected in one patient after mitral valve replacement. The intimal tear of a type 1 aortic dissection was located with positive identification of the true and false lumina. A high incidence of mild asymptomatic mitral regurgitation was found in patients undergoing coronary artery bypass grafting (CABG).