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Both dipyridamole myocardial perfusion imaging (cardiolite) and ambulatory ECG monitoring (Holter) for silent ischaemia have been found to be useful for stratification of cardiac risk in patients undergoing vascular surgery. The purpose of this study was to compare the diagnostic accuracy of these two non-invasive tests for prediction of perioperative cardiac events. One hundred patients (86 males, 14 females; mean age 67 +/- 8 years) underwent out-patient 48 h Holter monitoring and cardiolite imaging prior to vascular surgery (70 abdominal aortic aneurysm, 21 aortobifemoral, nine femoralpopliteal grafts). Ischaemia on Holter was defined as one or more episodes of ST segment depression 1 mm or greater, lasting 1 min or longer. Myocardial perfusion imaging was carried out with the high dose dipyridamole protocol (0.84 mg/kg), cardiolite and planar imaging. Ischaemia was defined as a segmental perfusion abnormality following dipyridamole with improved perfusion on rest imaging. Holter was positive for ischaemia in 34/100 patients (34%). Cardiolite scans were positive for ischaemia in 30/100 patients (30%). Perioperative myocardial infarction occurred in nine patients (two cardiac deaths). [table: see text] The diagnostic accuracy of the two tests was similar, with a low positive predictive value of 15-20%, and an extremely high negative predictive value of 94-96%. The event rate in patients with both tests negative was 2/48 (4.2%), with only one test positive 3/40 (7.5%) and with both tests positive 4/12 (33%). A reasonable approach to risk stratification would be to obtain either a Holter or cardiolite scan initially.(ABSTRACT TRUNCATED AT 250 WORDS)

The goal of this randomized study was to determine whether combined general and epidural anaesthesia with postoperative epidural analgesia, compared with general anaesthesia and postoperative intravenous analgesia, reduced the incidence of perioperative myocardial ischaemia in patients undergoing elective aortic surgery. Patients were randomly assigned to one of two groups. One group (EPI, n = 48) received combined general and epidural anaesthesia and postoperative epidural analgesia for 48 hrs. The other group (GA, n = 51) received general anaesthesia followed by postoperative intravenous analgesia. Anaesthetic goals were to maintain haemodynamic stability (± 20% of preoperative values), and a stroke volume > 1 ml · kg−1. A Holter monitor was attached to each patient the day before surgery. Leads 11, V2, and V5 were monitored. Myocardial ischaemia was defined as ST segment depression > 1 mm measured at 80 millisec beyond the J point or an elevation of 2 mm 60 millisec beyond the J point which lasted > 60 sec. An event that lasted > 60 sec but returned to the baseline for > 60 sec and then recurred, was counted as two separate events. The Holter tapes were reviewed by a cardiologist blind to the patient’s group. There were no demographic differences between the two groups. Myocardial ischaemia was common; it occurred in 55% of patients. In hospital, preoperative ischaemia was uncommon (CA = 3, EP1 = 8). Intraoperative ischaemia was common (GA = 18, EP1 = 25). Mesenteric traction produced the largest number of ischaemic (GA = 11, EP1 =11) events. Postoperative ischaemia was most common on the day of surgery. Termination of epidural analgesia produced a burst of ischaemia (60 events in 9 patients) Combined general and epidural anaesthesia and postoperative epidural analgesia do not reduce the incidence of myocardial ischaemia or morbidity compared with general anaesthesia and postoperative intravenous analgesia.

Platelets are implicated both in acute thrombotic events and, through platelet-derived growth factor, in the development of intimal hyperplasia. We have investigated, in vivo , the influence of aspirin and dipyridamole on vascular smooth muscle cell proliferation and DNA synthesis following balloon catheter injury. Fifty-eight male, New Zealand white rabbits were divided equally into two groups; the test group was fed aspirin (14 mg/kg/day) and dipyridamole (9 mg/kg/day) from 2 days prior to surgery until sacrifice at 1, 2, 3, 4, 7, 14, or 28 days after injury. All animals were sacrificed 1 h after injection of [ 3 H]thymidine and the smooth muscle cell DNA specific activity and total kinetic activity were determined. Intimal hyperplasia was measured by light microscopy and intimal nuclear proliferation was determined by counting nuclei per millimeter of internal elastic lamina. Nuclear proliferation was maximal at 14 days (25 ± 1.2) but intimal hyperplasia was still increasing at 28 days. DNA specific activity after 24 hr (test: 4 ± 2 dpm/μg DNA; control: 3.3 ± 3 dpm/μg DNA) was similar to basal levels in uninjured rabbits. DNA synthesis peaked in both groups between the second and third day (test: 177 ± 27 dpm/μg DNA; control: 185 ± 39 dpm/μg DNA) and then declined slowly toward baseline values. There was no significant difference between treated and normal rabbits in either [ 3 H]thymidine incorporation, nuclear proliferation, or development of intimal hyperplasia despite 90% inhibition of platelet aggregation and a significant reduction (78%) in [ 14 C]serotonin release following collagen challenge (6 μg/ml). These results suggest the presence of another significant growth factor(s) for vascular smooth muscle in the rabbit as global interference with platelets does not inhibit smooth muscle proliferation.