David Schechter

Importance of long-duration postoperative ST-segment depression in cardiac morbidity after vascular surgery

Major vascular surgery is associated with a high incidence of cardiac ischaemic complications. By means of continuous perioperative electrocardiographic recording, we studied 151 consecutive patients undergoing major vascular surgery to find out the characteristics of any myocardial ischaemia and the relation to outcome. 13 (8.6%) patients had postoperative cardiac events (6 myocardial infarctions, 2 unstable angina, and 5 congestive heart failure). There were 342 perioperative ischaemic episodes shown by ST-segment depression; 164 (48%) occurred postoperatively. Postoperative ischaemic episodes were significantly longer than episodes before or during operations (3.2 vs 1.7 and 1.5 min per h monitored, respectively, p < 0.001). Both Detskys cardiac risk index and long-duration (> 2 h) preoperative ischaemia were predictive of postoperative cardiac complications (odds ratios in univariate analysis 3.3, p = 0.03, and 7.2, p = 0.009, respectively). However, long-duration (> 2 h) postoperative ischaemia was the only factor significantly associated with cardiac morbidity in multivariate logistic regression analysis (odds ratio 21.7, p = 0.001). Long-duration ST-segment depression preceded most (84.6%) postoperative cardiac events, including myocardial infarctions, and no cardiac event was preceded by ST-segment elevation. 5 of the 6 postoperative myocardial infarctions were non-Q-wave infarctions. We conclude that long-duration subendocardial ischaemia, rather than acute coronary artery occlusion, may bring about postoperative myocardial injury and complications.

Preoperative Thallium Scanning, Selective Coronary Revascularization, and Long-Term Survival After Carotid Endarterectomy

BACKGROUND AND PURPOSEnLong-term survival in patients after carotid endarterectomy (CEA) is determined mainly by their concomitant cardiac disease. We tested to determine whether preoperative thallium scanning (PTS) and subsequent selective coronary revascularization (CR), by either percutaneous transluminal coronary angioplasty (PTCA) or coronary artery bypass grafting (CABG), improve long-term survival after CEA.nnnMETHODSnTwo hundred twenty-six of 255 consecutive patients (88%) undergoing CEA from 1990 to 1996 had PTS. Those with significant reversible defects on PTS were referred for coronary angiography and possible CR. Patients who had undergone PTS were divided into the following 4 groups: group 1, normal or mild defects on PTS; group 2, moderate-severe fixed and/or reversible defects in patients who did not undergo CR; group 3, patients who had CR secondary to their PTS results; and group 4, patients who had CR in the past that was not related to the PTS. Perioperative data were prospectively recorded, and data on long-term survival and cardiac and neurological complications were collected.nnnRESULTSnSeventy-seven patients (34%) had preoperative coronary angiography, and 42 (19%) had subsequent CR: preoperative PTCA or CABG in 24, combined CEA+CABG in 10, and post-CEA CABG in 8 patients. No deaths resulted from the coronary angiography, CR, or CEA. Six patients had perioperative nonfatal myocardial infarction and 8 had stroke. During the follow-up (40+/-23 months), 47 patients (18%) died, 31 (66%) from cardiac disease and 4 (8.5%) from stroke. Independent predictors of long-term overall mortality were diabetes mellitus, preoperative T-wave inversion on ECG, lower-extremity arterial disease, and history of neurological symptoms [exp(beta)=3. 5, 3.4, 2.5, and 2.4; P=0.0003, 0.0004, 0.01, and 0.04, respectively]. In addition, preoperative moderate-severe thallium defect without CR (group 2) independently predicted long-term cardiac mortality [exp(beta)=2.8; P=0.04]. Patients with preoperative CR (group 3) had long-term survival rate similar to that of group 1 and significantly better than that of group 2 (P=0. 02).nnnCONCLUSIONSnPTS predicts long-term survival, and selective CR based on the thallium results improves the survival rate of patients undergoing CEA.

Tc-99m mercaptoacetyltriglycine clearance : Comparison of camera-assisted methods

Purpose To compare the accuracy of three camera-assisted methods for the measurement of Tc-99m mercaptoacetyltriglycine (MAG3) clearance. Materials and Methods MAG3 renal scintigraphy was performed in 21 adults with different degrees of renal function. Posterior views were obtained that included the heart and the kidneys in the camera field of view. The syringe for injection was imaged before and after injection. Blood samples were drawn 24 and 43 minutes after injection and plasma radioactivity was measured. Three camera-assisted techniques to measure MAG3 clearance were tested: 1) Biexponential fitting of the left ventricular curve, normalized to plasma activity at 24 minutes; 2) calculation of clearance by relating the integral of the plasma curve (normalized to plasma activity) to the kidney activity using the Rutland-Patlak space method; and 3) a regression equation measuring clearance from the percentage of the injected dose accumulating in the kidneys during the 1- to 2.5-minute period. The camera-assisted clearances were compared with the single-sample MAG3 clearances calculated using the Russell equation. Linear regression analysis was used to measure the correlation between the camera-based methods and the single-sample techniques. Results Correlation with r > 0.900 was found for all three techniques. The difference in correlation coefficients between the three methods was not significant; however, the regression line of method 3 was significantly closer to the line of identity (P = 0.005). Conclusion Method 3 most closely fits the line of identity and is probably the most practical because no blood sample is needed.

Heart Rate Variability as a Marker of Myocardial Perfusion

RR variability (HRV), an independent predictor of death following myocardial infarction, may also be related to other features of coronary artery disease. We evaluated its ability to differentiate among sedentary patients with chest pain ≥45 years of age demonstrating either normal or abnormal myocardial perfusion with rest and exercise thallium-210 tomographic imaging. The major HRV difference between 48 men and 50 women with normal perfusion was a significantly higher high frequency power in women. No significant differences in mean HRV values were found between the 57 men with abnormal perfusion scans and the 48 men with normal perfusion. In both men and women with normal perfusion scans, duration of exercise was significantly related to age. In men with abnormal scans, impaired myocardial perfusion alters the relationship between exercise duration and age, and a group of individuals with diminished HRV and low levels of physical fitness, regardless of age, can be identified. Despite these latter selective findings, we conclude that HRV is not a sensitive indicator to differentiate patients with normal and abnormal myocardial perfusion.

Radioiodine Hot Hand Sign

A 32-year-old woman was referred for a whole body 1-131 scan 4 weeks after total thyroidectomy for differentiated thyroid carcinoma. Initial scan 72 hours after administration of 5 mCi of 1-131 disclosed no abnormal foci. A post-treatment scan performed 10 days after 150 mCi of 1-131 showed abnormal uptake throughout the left chest, suggestive of mediastinal and pulmonary metastases, and tracer activity in both hands. Absence of tracer uptake on pre-treatment scan, along with tracer in hands, alerted staff to possible contamination. Repeat imaging of chest after washing revealed no evidence of abnormal tracer uptake. Abnormal uptake on pretreatment scan, even if false positive, may lead to erroneous I-131 administration. It is important to be aware of possible contamination, especially when discordant findings exist, as observed in our patient.

Breast Artifact in Planar Cardiac Imaging: A Comparison of 201TI to Sestamibi-99mTc

Breast artifact occurrence during 201T1 myocardial image interpretation is a significant problem. We serially evaluated 3 female patients utilizing exercise treadmill perfusion studies in order to assess the potential role of 99mTc-Sestamibi (MIBI) imaging in the setting of documented 201T1 breast artifact. Both visual and quantitative analyses revealed no superiority of 99mTc-MIBI over 201T1 imaging in reference to avoidance of breast artifact. The variation in artifactual cardiac imaging defects in the 3 patients most probably reflected variations in breast positioning. Finally, the ability to assess ventricular wall motion via gated 99mTc-MIBI imaging may help to confirm an artifactual versus an actual myocardial perfusion abnormality.

980-90 Superior Vena Cava Versus Right Atrium Central Venous Catheter Placement Avoids Thrombosis: The Role of Transesophageal Echocardiography in Diagnosis and Evaluation — A Prospective Study

Intravenous central line (Hickman type) catheters (CL) are routinely used in the management of chronically ill patients. These CLs are placed in the superior vena cava (SVC) or right atrium (RA) and are often associated with complications, mainly thrombosis or infection. The introduction of transesophageal echo (TEE) has significantly improved the imaging of intracardiac structures, especially left atrial thrombi and right atrial masses. We explored the use and importance of TEE (and compared to transthoracic echo (ITTE)) for early evaluation of CL placement and detection of related masses. Methods We prospectively studied fifty-five (55) bone marrow transplantation (BMT) patients by TTE and TEE at an asymptomatic stage within a week post-Hickman catheter (CL) implantation and on a follow-up study after 6–8 weeks. We looked for the exact CL tip placement and searched for possible presence of any related abnormalities. Results Of the fifty-five patients in the first study, the CL tips could be demonstrated in 48 (87%) of them by TEE compared to only 4 (8%) by TTE. 13 were placed in the right atrium (RA), 8 at he superior vena cave-right atrium junction (SVC-RA), and 27 in the s superior vena-cava (SVC). An abnormal mass was found in six patients (12.5%). All of these presumed thrombi were seen in patients in whom the CL tip was placed in the RA (Table) No. of Patients CL location Thrombi 27 SVC 0 8 SVC-RA 0 13 RA 6 (pxa0lxa00.001 Conclusions TEE studies performed in an asymptomatic setting of BMT patients within a week post-routine CL implantation demonstrated unexpected, asymptomatic catheter-tip related masses, consistent with thrombosis, in the RA of 12.5% of patients. These findings suggest that: (1) CL should be placed in the SVC or SVC-RA junction, in contrast to the RA. (2) TEE is a useful tool for guiding CL’s placement in severely immunocompromised, chronically ill patients, to avoid formation of thrombi.

Left ventricular thrombus identification. A scintigraphic and echocardiographic correlation.

A prominent and protruding left ventricular filling defect was noted on a routine radionuclide ventriculogram in a patient with congestive heart failure. An echocardiogram further documented the existence of a septal thrombus, which was suspected by radionuclide ventriculogram