Platelet function assessed by ROTEM®platelet in patients receiving antiplatelet therapy during cardiac and vascular surgery.

Patients undergoing coronary artery bypass graft (CABG) surgery or carotid endarterectomy (CEA) continue antiplatelet therapy perioperatively, which may increase bleeding risk. We aimed to investigate whether Rotational thromboelastometry (ROTEM®) platelet, a newly marketed platelet function analysis, would detect antiplatelet therapy in CABG and CEA patients; whether detection of reduced platelet function was associated with increased bleeding; and whether ex vivo desmopressin increased platelet function. We included 20 CABG patients continuing aspirin and 20 CEA patients continuing clopidogrel (n = 1) or clopidogrel and aspirin (n = 19). Platelet function was analyzed with ROTEM®platelet and light transmission aggregometry (LTA). According to the lower reference limit, ROTEM®platelet managed to detect aspirin, but clopidogrel detection was inadequate compared to LTA. Using a previously published cut-off for bleeding risk, 6 (30%) patients receiving aspirin and 4 (21%) patients receiving both clopidogrel and aspirin demonstrated platelet function below this cut-off. One of the four CEA patients below the cut-off died from intracerebral hemorrhage postoperatively. CABG patients below (n = 6) and above (n = 14) the cut-off did not differ in chest tube output (median [range]: 373 ml [250-900] vs. 368 ml [195-820]). Ex vivo addition of desmopressin did not increase platelet function. In conclusion, ROTEM®platelet does reveal aspirin treatment whereas clopidogrel treatment is most often overlooked. Due to low bleeding in the study population, it was not possible to conclude on the association with bleeding risk.

Apical myocardial stunning in a large size porcine model assessed by strain and strain rate echocardiography.

BACKGROUND: Warm ischemia and subsequent reperfusion of the heart can induce a temporary dysfunction known as myocardial stunning. The aim of this study was to investigate the ability of tissue Doppler imaging (TDI) to quantify longitudinal myocardial stunning close to the apex, and perform a comparison with sonomicrometry using a well-established large size porcine model. METHODS: In anesthetized pigs, postischemic myocardial stunning was induced by occluding LAD for 15 min followed by 90 min reperfusion (n = 7). Long-axis strain and strain rate was quantified by both TDI and sonomicrometry. RESULTS: During reperfusion, peak systolic strain measured by TDI decreased from -11.2% (+/-3.0) at baseline to -4.9% (+/-3.6), -3.4% (+/-2.9), and -4.3% (+/-5.0) at 30, 60, and 90 min, respectively (all P < 0.007). Postsystolic strain increased from -1.3% (+/-1.6) at baseline to -6.4% (+/-4.4), -4.8% (+/-4.0), and -5.2% (+/-2.7) by TDI in the reperfusion phase (all P < 0.048 except at 60 min of reperfusion (P = 0.081)). Postsystolic index increased from 0.10 (+/-0.13) at baseline to 0.56 (+/-0.24), 0.54 (+/-0.30), and 0.64 (+/-0.37) subsequently (all P < 0.012). [Correction added after online publication 30-May-2007: In the preceding sentence, the phrase 'Postsystolic index decreased from 0.10 (+/-0.13)' was changed to 'Postsystolic index increased from 0.10 (+/-0.13).'] Difference-mean and line of identity plots did not disclose any systematic error, but revealed substantial variation, indicating a mismatch between TDI and sonomicrometry. CONCLUSIONS: It is feasible to quantify postischemic myocardial stunning by TDI in a large size porcine model using longitudinal postsystolic shortening, and postsystolic index as indicators. TDI and sonomicrometry data reach the same end point, but the two techniques are not interchangeable when investigating myocardial stunning close to apex in reference to longitudinal strain and strain rate.

Transesophageal tissue Doppler echocardiography for evaluation of myocardial function during aortic valve replacement.

OBJECTIVE: Tissue Doppler imaging is an evolving ultrasound technology that, compared with traditional echocardiography, promises reduced subjectivity in the assessment of myocardial performance and contributes new information on myocardial function. The aim of this study was to evaluate the feasibility of transesophageal tissue Doppler imaging in the setting of aortic valve replacement. DESIGN: Feasibility study. SETTING: Aarhus University Hospital, Denmark. PARTICIPANTS: Twelve patients with isolated aortic valve stenosis or combined ischemic cardiomyopathy and aortic valve stenosis scheduled for elective aortic valve replacement were included. INTERVENTION: Transgastric short-axis recordings of the left ventricular anterior wall were performed using Vivid-7 technology (GE Healthcare, Horten, Norway) with activated tissue Doppler imaging before sternotomy, at intervals during progressive withdrawal of cardiopulmonary bypass, and within 1 hour after transfer to the postoperative care unit. Data were postprocessed for assessment of systolic radial function with the tissue Doppler modalities, tissue velocity, end-systolic strain rate, and strain by using dedicated software. RESULTS: Accurate tissue Doppler data were obtained for all patients at baseline and postoperatively. During the gradual loading of the left ventricle, velocity measurements were all obtained accurately, whereas 8% to 25 % of strain and strain-rate measurements were considered unreliable. Immediately after cardioplegia, 33% to 58% of measurements were unreliable. CONCLUSIONS: Transesophageal tissue Doppler is feasible in the intraoperative setting, although unreliable data acquisition occurs during cardiopulmonary bypass. Tissue Doppler is a promising quantitative tool for monitoring of myocardial function within minutes and may also reveal new information on myocardial function in patients undergoing thoracic surgery.