Platelet morphology in patients with mechanical circulatory support.
OBJECTIVE
Mechanical circulatory support is a therapy for patients with end stage cardiac insufficiency. The thromboembolic events are feared complications during support, due to the surface thrombogenicity of the implanted device. Activated blood platelets play a major role in this context. Consequently the platelet morphology of patients was investigated.


METHODS
Platelets of eight patients were observed by means of scanning electron microscopy during the period of support with the Novacor left ventricular assist system N100. Blood was collected preoperatively and daily during the first week as well as weekly during the first 3 months. Samples were fixed with cacodylic-acid buffered glutaraldehyde. Platelet alterations were classified as non-activated, activated and aggregated, based on the so-called 'shape change' morphology. In addition, blood coagulation parameters were evaluated (e.g. activated partial thromboplastin time, prothrombin time, antithrombin III).


RESULTS
Preoperatively, 15.0 +/- 4.6% (overall mean values) of activated platelets were found. Within the first postoperative week, the mean level of activated platelets increased to 32.8 +/- 8.0% (P < 0.05). Comparing short- (< 30 days; n = 4) vs. long-period (> 30 days; n = 4) support, a significant difference of activated platelets was evaluated (24.3 +/- 3.3% vs. 34.8 +/- 3.4%, P = 0.004). A correlation was found between the values of activated clotting time and activated platelets. Specific platelet deformations and damages appeared during support, which could not be found preoperatively.


CONCLUSIONS
The platelet morphology showed alterations in all patients probably most strongly induced by the surface activation of the implanted device. These observations should be taken into consideration in management of postoperative anticoagulation therapy.
Dewald
O
O
Department of Cardiac Surgery, Grosshadern Medical Center, Ludwig Maximilians University of Munich, Germany.
Fischlein
T
T
Vetter
H O
HO
Schmitz
C
C
Gödje
O
O
Göhring
P
P
Reichart
B
B
D000328:Adult; D001672:Biocompatible Materials; D001780:Blood Coagulation Tests; D001792:Blood Platelets / Q000648:ultrastructure*; D002311:Cardiomyopathy, Dilated / Q000097:blood / Q000628:therapy; D005260:Female; D006353:Heart-Assist Devices; D006801:Humans; D008297:Male; D008855:Microscopy, Electron, Scanning; D010979:Platelet Function Tests; D013997:Time Factors
D001672:Biocompatible Materials