Evaluation of platelet reactivity in patients with valvular heart disease

Abstract

Transmission electron microscopy with a standardized in vitro method was used to evaluate the degree of blood platelet reactivity in 72 normal subjects and 72 patients with valvular heart disease. Among the patients with abnormal natural heart valves, 51 had either aortic insufficiency or aortic stenosis, and 21 patients showed either mitral insufficiency or mitral stenosis. For normal subjects, the platelet differential counts were dominated by the dendritic type platelet, and only a few platelets showed cytoplasmic spreading between adjacent pseudopodia (spread type). A hyperactive response was defined as greater than 20% of the spread type platelet or more than 93 aggregates per 100 single platelets counted, or both. Only 6 (8%) of the 72 normal subjects showed hyperactive platelets. In contrast, 45 (62%) of the 72 patients with valvular heart disease had hyperactive platelets (p less than 0.01). For patients with abnormal valves, the mean percent of the spread type platelet was 35% with a mean value of 105 platelet aggregates. The increased level of platelet reactivity was independent of both the position of the valve (aortic versus mitral) and its functional status (insufficient versus stenotic). Disturbed flow and the exposure of subendothelial thrombus-producing materials are features associated with abnormal heart valves. These factors, which usually occur in combination, may explain the hyperactive platelet response found in these patients.

Evaluation of platelet function in dogs with cardiac disease using the PFA‐100 platelet function analyzer

“…These results suggest that dogs with cardiac murmurs have altered platelet function. This is in contrast to some initial reports in the human medical literature in which patients with valvular cardiac disease had platelets in an activated state as defined by increased platelet diameter 20 and increased numbers of spread‐type platelets 21 . However, studies to date in dogs have supported the finding of decreased platelet function in cardiac disease.…”

“…Cardiac disease has the potential to alter platelet function in humans and dogs, but there is conflicting information as to whether hypofunction or hyperfunction is present. In earlier studies in humans with cardiac disease, platelets were noted to be in an activated state 20,21 . The few studies reported in dogs have instead supported platelet hypofunction in cardiac disease 1–5 .…”

Relation between Sympathetic Overactivity and Left Atrial Spontaneous Echo Contrast in Patients with Mitral Stenosis and Sinus Rhythm

“…Percutaneous mitral balloon commissurotomy (PMBC) is now standard treatment for many patients with symptomatic MS. 29 Previous studies demonstrated that besides symptomatic improvement, platelet activity significantly decreases after an optimal PMBC. 30,31 Although, Chen et al 31 showed that the increase in the mitral valve area by PMBC accounts for the decrease in platelet activation, Riddle et al 32 found that the increase in platelet reactivity is independent of both the position of the valve and its functional status. Therefore, we suggested that there could be some other beneficial effects of PMBC on the platelet reactivity.…”

Acute Coronary Syndrome: Pathological Findings by Means of Electron Microscopy, Advance Imaging in Cardiology

“…Platelet differential count includes the percent of round, dendritic and spread type platelets. Also the number of platelet aggregates counted during classification of the 100 single platelets can be recorded through this technique [Riddle et al, 1983]. TEM can also be used for acute ischemic events related to cardiotoxic compounds.…”