diastolic dysfunction include transmitral Doppler velocities, time in-tervals, and myocardial Doppler indices obtained using Doppler tissueimaging. Eleven healthy volunteers were compared with 25 patientswithout LVH and with 37 patients with LVH. Differences betweenpatients with and without LVH existed for the following variables:mitral A wave and deceleration time, mitral E/A wave ratio, isovolumicrelaxation time, myocardial E velocity, myocardial isovolumic contrac-tion velocity, and myocardial isovolumic relaxation velocities. Whenmany of these variables were entered into a multivariate analysis topredict LVH, only myocardial isovolumic relaxation time and myocar-dial A wave duration correlated with wall thickness. Myocardial Dopp-ler velocities were more sensitive in detecting abnormalities of diastolicfunction than transmitral Doppler.

Implication: Doppler tissue imaging is a new technology that isrelatively simple to use. The measure of myocardial velocities is rela-tively load independent and may be a more sensitive measure ofdiastolic dysfunction than the currently used methods of Dopplermeasure.

Waggoner AD, Bierig SM: Tissue Doppler imaging:A useful echocardiographic method for the cardiacsonographer to assess systolic and diastolic ventricu-lar function. J Am Soc Echocardiogr 14:1143-1152,2001

Doppler tissue imaging is a relatively new technique that can be usedto measure echocardiographically systolic and diastolic ventricularfunction. Myocardial velocities have 3 main components: systolic(which may be biphasic), early diastolic, and late diastolic velocities.Isovolumic relaxation and contraction velocities can also be measuredand correlate with clinical parameters. This article is an excellentreview of Doppler tissue imaging with respect to the instrumentation,technique, and applications to patients with myocardial disorders.

Implication: Doppler tissue imaging is feasible to measure diastolicfunction, global ventricular systolic function, and regional systolicdysfunction.

THROMBOSIS AND MYOCARDIAL INFARCTION

Geissler HJ, Davis KL, Buja M: Esmolol and car-diopulmonary bypass during reperfusion reducemyocardial infarct size in dogs. Ann Thorac Surg72:1964-1969, 2001

It is common practice to use �-blockade in patients with acutemyocardial ischemia. In this group of patients, �-blockade has beenshown to reduce myocardial infarct size. In this study, the authorsexamined the use of esmolol in limiting infarct size in a post–cardio-pulmonary bypass (CPB) dog model. After the initiation of CPB, 20dogs underwent 2 hours of regional left ventricular ischemia, followedby 2 hours of reperfusion. In 11 dogs, �-blockade was initiated with theonset of reperfusion (esmolol group). The remaining 9 dogs received notreatment. Infarct size was determined by tetrazolium chloride staining.Myocardial water content (MWC) and ultrastructural damage weredetermined from a myocardial biopsy specimen. In the esmolol group,infarct size was reduced compared with control (49% v 68%; p � 0.05).After 2 hours of ischemia, there was no difference in MWC betweenthe 2 groups; after 2 hours of reperfusion, MWC of ischemic myocar-dium was lower in the esmolol group compared with control (p �0.05). Myocardial cellular ischemia-reperfusion changes were similarin both groups. There are reasons why �-blockade seems to be protec-tive in the setting of reperfusion ischemia, including higher coronarysinus oxygen saturation, lower levels of malondialdehyde (a marker of

lipid peroxidation), and higher levels of oxygen free radical scavengers,such as glutathione and superoxide dismutase.

Implication: Using �-blockade during reperfusion while on CPB, itmay be possible to reduce myocardial injury. This effect seems to existeven if initiated as late as the onset of reperfusion. More studies arenecessary before the use of �-blockade becomes widespread in pre-venting post-CPB–induced reperfusion injury.

D’Ancona G, Donias HW, Karamanoukian RL, etal: OPCAB therapy survey: Off-pump clopidogrel,aspirin or both therapy survey. Heart Surg Forum4:354-358, 2001

Anticoagulation and antithrombotic strategies for off-pump coronaryartery bypass (OPCAB) surgery are variable and depend on the surgeonand institution. A questionnaire survey was sent randomly to 800cardiothoracic surgeons, and a 38% response rate was received. Ofrespondents, 16% used antiplatelet therapy preoperatively, and 88%used it postoperatively. Aspirin was the predominant agent used forthrombosis prophylaxis. Heparin protocols varied with most surgeonspreferring half-dose heparin (54%) to achieve an activated coagulationtime between 300 and 400 seconds. Of surgeons, 60% used a full doseof protamine to reverse the heparin.

Implication: Prospective randomized data are lacking with respectto optimal anticoagulation and antithrombotic regimens for OPCABsurgery. Until published studies show superiority of certain techniques,surgical preferences will continue to be highly variable.

Yende S, Wunderink RG: Effect of clopidogrel onbleeding after coronary artery bypass surgery. CritCare Med 29:2271-2275, 2001

Clopidogrel is a platelet antagonist medication that has proved to beefficacious in reducing adverse coronary and cerebrovascular events inpatients with atherosclerotic vascular disease. Bleeding after cardiacsurgery is often related to platelet dysfunction and may be exaggeratedin patients taking concomitant antiplatelet medications. A prospectiveobservational study was undertaken in 247 cardiac surgical patients.Endpoints were reoperation for bleeding and transfusion requirements.Patients taking clopidogrel had a 9% incidence of reexploration com-pared with 1.6% in patients not taking the drug (p � 0.01). The oddsratio for clopidogrel as a risk factor for reexploration was 6.9 (95%confidence interval, 1.6 to 30). The percentage of patients receivingtransfusions of packed red blood cells and cryoprecipitate also wassignificantly increased in the clopidogrel patients.

Implication: Although this was not a randomized or blinded trial,observational evidence suggests an increased risk of bleeding andtransfusion requirements in patients taking clopidogrel before cardiacsurgery. The optimal number of days for cessation of clopidogreltherapy without increasing the risk of a thrombotic event has not yetbeen identified.

Salartash K, Sternbergh WC, York JW, MoneySR: Comparison of open transabdominal AAA repairwith endovascular AAA repair in reduction of post-operative stress response. Ann Vasc Surg 15:53-59,2001

Major vascular surgery, such as abdominal aortic aneurysm (AAA)repair, often causes a hypermetabolic stress response, the patient’sphysiologic response to the trauma of surgery. Each major organsystem of the body responds by altering its activity to compensate forthe increased metabolic load that surgery causes. In the last few years,

387LITERATURE REVIEW