Comparison of the findings on preoperative dipyridamole perfusion scintigraphy and intraoperative transesophageal echocardiography: implications regarding the identification of myocardium at ischemic risk.

The evidence of myocardium at potential ischemic risk on preoperative dipyridamole perfusion scintigraphy was compared with that of manifest ischemia on intraoperative transesophageal echocardiography in 26 patients at high risk of a coronary event undergoing noncardiac surgery. The clinical outcome was also assessed. Induced intraoperative wall motion abnormalities were more common in patients and myocardial segments with, than in those without, a preoperative reversible perfusion defect (both p less than 0.05). Conversely, a preoperative reversible perfusion defect was more common in patients and segments with, than in those without, a new intraoperative wall motion abnormality (both p less than 0.05). Six patients, five with a reversible scintigraphic defect but only three with a new wall motion abnormality, had a hard perioperative ischemic event. Events occurred more often among patients with, than in those without, a reversible perioperative scintigraphic defect (5 [33%] of 15 vs. 1 [9%] of 11) but this difference did not reach significance (p = 0.14), probably owing to the sample size. Intraoperative wall motion abnormalities were all reversible and did not differentiate between risk groups; these findings were possibly influenced by treatment. These preliminary data support the known relation between reversible scintigraphic defects and perioperative events and identify another manifestation of ischemic risk in the relation between reversible scintigraphic defects and induced intraoperative wall motion abnormalities. The value of intraoperative echocardiography in identifying ischemia and guiding therapy in patients with a reversible scintigraphic abnormality should be further assessed.

Anaphylactoid reactions to vascular graft material presenting with vasodilation and subsequent disseminated intravascular coagulation.

This report describes five patients who had immediate adverse reactions following placement of a vascular graft. All had unusually persistent decreases in systemic vascular resistance, and four of these patients had bleeding as an early manifestation of this reaction. In two of three patients in whom the graft was replaced, uneventful recovery followed. Both patients in whom the graft was not replaced died. Blood samples from two of the patients demonstrated activation of complement and of the kinin system, whereas control patients did not demonstrate increased levels of activation products from these cascade systems. Recognition of this syndrome is important to patient survival, which appears to depend on rapid replacement of the graft.

Does anesthetic technique make a difference? Augmentation of systolic blood pressure during carotid endarterectomy: effects of phenylephrine versus light anesthesia and of isoflurane versus halothane on the incidence of myocardial ischemia.

Whether anesthetic technique affected the incidence of myocardial ischemia in 60 patients undergoing carotid endarterectomy was investigated. The patients were randomly assigned to receive halothane or isoflurane (with nitrous oxide) either at a low concentration alone or at a higher concentration with phenylephrine added to support blood pressure. Blood pressure was maintained within 20% of each patient's average ward systolic pressure. Seven leads of electrocardiograms (ECG) and echocardiograms were analyzed for segmental wall motion. The echocardiograms were analyzed using standard formulae for end-systolic meridional wall stress (SWS) and rate-corrected velocity of fiber shortening (Vcfc). Because of the nature of these calculations, only echocardiograms with normal regional wall motion could be accurately analyzed. The patients had postoperative ECG and creatinine phosphokinase (CPK) isoenzyme determinations and regularly scheduled clinical examinations to detect perioperative myocardial infarction and neurologic deficits. Although blood pressures were similar, the patients who received a higher concentration of anesthetic plus phenylephrine had a higher wall stress, regardless of the choice of anesthetic agent. All four techniques allowed provision of the same stump pressures (the marker surgeons used for adequacy of collateral carotid flow). No difference could be found in wall stress or incidence of myocardial ischemia between isoflurane and halothane. The patients who received phenylephrine had a threefold greater incidence of myocardial ischemia than did the patients who had light anesthesia to maintain similar systolic blood pressures and stump pressures. The groups were demographically and hemodynamically similar; in particular, the heart rates were not different.(ABSTRACT TRUNCATED AT 250 WORDS)

Intraoperative detection of myocardial ischemia in high-risk patients: electrocardiography versus two-dimensional transesophageal echocardiography.

Because acute segmental wall motion abnormalities (SWMAs) of the left ventricle are highly sensitive and specific indicators of myocardial ischemia, this study compared the incidence and significance of ischemia, as detected by two-dimensional transesophageal echocardiography and surface electrocardiography, during anesthesia and surgery in patients at high risk of myocardial ischemia. During surgery, 24 of the 50 patients studied had new SWMAs, whereas only six had ST segment changes. All patients with ST segment changes also had new SWMAs: in three instances, SWMAs occurred before the ST segment change, and in three instances, they occurred simultaneously. All three patients who had intraoperative myocardial infarctions also had persistent intraoperative SWMAs, whereas only one patient had ST segment changes. Ten healthy patients requiring noncardiovascular surgery were monitored similarly; none of these had SWMAs, ST segment changes, or myocardial infarction. This study demonstrates the superiority of two-dimensional transesophageal echocardiography over electrocardiography for the intraoperative detection of myocardial ischemia. Furthermore, when new SWMAs persist to the conclusion of surgery, myocardial infarction is likely to have occurred.