Detection of cerebral microemboli in APS--introducing a novel investigation method and implications of analogies with carotid artery disease

Transcranial Doppler findings in antiphospholipid syndrome

INTRODUCTION

Transcranial Doppler is a method that enables the assessment of different cerebral hemodynamic parameters. It also allows for the evaluation of the presence of right-to-left circulation shunts (RLS) and for the detection of microembolic signals (MESs), which might be associated with an increased risk of cerebrovascular events. For instance, the presence of MESs on transcranial Doppler in patients with systemic lupus erythematous (SLE) and antiphospholipid syndrome (APS) is associated with an increased risk of stroke. Therefore, transcranial Doppler could be a useful tool for stroke risk stratification in these patients.

OBJECTIVE

Our objective was to evaluate transcranial Doppler cerebral mean blood flow velocities as well as the presence of MESs and RLS in patients with antiphospholipid syndrome and SLE.

PATIENTS AND METHODS

Twenty-two patients with primary APS (PAPS), 24 patients with secondary APS (SAPS), 27 patients with SLE without APS and 21 healthy controls were evaluated. Clinical and epidemiological data were compiled from medical charts, and all subjects underwent transcranial Doppler examination with breath-holding index calculation. Both middle cerebral arteries were monitored for 60 min for the detection of MESs. RLS was investigated with agitated saline injected as a bolus.

RESULTS

There were no significant differences in mean blood flow velocities among the groups. MESs were more frequently found in patients with SLE when compared with controls and patients with APS (SLE: 17.4%, SAPS: 4.3%, PAPS: 0%, controls: 0%, p = 0.03). Anticoagulant therapy was more frequently used in the APS group (PAPS: 81.8%, SAPS: 75.2%, SLE: 1.7%, p < 0.001). Patients with APS had a higher frequency of RLS when compared with volunteers (63.6% versus 38.1%, p = 0.05). Breath-holding index values tended to be lower in patients with SAPS than in control subjects and patients with PAPS and SLE ( p = 0.06).

CONCLUSIONS

Patients with APS had a higher frequency of RLS than healthy controls. This finding alerts to the importance of cardiac investigation in patients with stroke and APS, because further therapies such as RLS occlusion might eventually add protection. The higher frequency of MES in patients with SLE could suggest an effect of anticoagulant therapy on MES prevention, more frequently used in patients with APS.

Cardiac imaging in rheumatic diseases

The majority of the imaging techniques in cardiology could be applied in rheumatic diseases (RDs), such as echocardiography, single-photon emission computed tomography (SPECT), radionuclide ventriculography, angiography, cardiovascular MRI and CT. Inflammatory pericardial involvement is the most common cardiac manifestation in various forms of RD. Echocardiography is the gold standard for diagnosis of pericardial abnormalities, demonstrating location and amount of pericardial effusion. Cardiac MRI and CT can be used to assess the features of pericardial effusions and pericardial structures. In patients with valvular heart disease in RD, transoesophageal echocardiography is a superior method and offers reliable information about valve morphology, the severity of the disease and left ventricular (LV) function. In addition, cardiac MRI is a valuable tool for the evaluation of valvular stenosis and regurgitation severity. Myocardial involvement in RD is demonstrated by abnormalities in LV size and function, indicating myocardial inflammation. In these patients Doppler echocardiography and myocardial tissue imaging can provide essential diagnostic information. Both LV angiography and cardiac MRI can provide reliable information on LV size, function and mass. In patients with coronary disease associated with RD, LV ejection fraction and ventricular wall motion can be assessed by echocardiography, radionuclide ventriculography, gated SPECT and MRI. Three-dimensional (3D) echocardiography is considered superior to 2D echocardiographic techniques. Stress echocardiography is the most used method for detection of myocardial ischaemia. The only accurate visualization of the coronary arteries is by selective coronary arteriography, which remains the gold standard. Although new non-invasive techniques have been developed, including CT and MRI angiography, some limitations apply.

Antiphospholipid antibodies in young adults with stroke

BACKGROUND

Antiphospholipid antibodies have been associated with a clinical syndrome consisting thrombosis and recurrent, unexplained fetal loss.

METHODS

The literature pertaining to stroke associated with antiphospholipid antibodies, with emphasis on stroke in young adults, was reviewed.

RESULTS

Antiphospholipid antibodies are an independent risk factor for stroke in young adults in five of six studies. Multiple antiphospholipid specificities or the Lupus Anticoagulant were tested in addition to anticardiolipin antibody in these studies. In the single study that found no increased risk for stroke, only anticardiolipin antibody was tested. Only one of these studies evaluated for risk of recurrent stroke in young adults with antiphospholipid antibodies and found it to be increased. No treatment trials have been conducted in young adults with antiphospholipid antibodies and stroke. In the single treatment trial comparing aspirin and low-INR producing doses of warfarin to prevent recurrent stroke, both were found to be equally effective.

CONCLUSIONS

Antiphospholipid antibodies, particularly Lupus Anticoagulant, is an independent risk factor for first and possibly recurrent ischemic stroke in young adults. The best therapeutic strategy for preventing antiphospholipid antibody-associated recurrent stroke is not clear.

Microembolus detection by transcranial doppler sonography

Microembolic signals can be detected by transcranial ultrasound as signals of high intensity and short duration. These signals represent circulating gaseous or solid particles. To optimize the differentiation from artefacts and the background signal and to facilitate the clinical use, several attempts have been made to automatize the detection of microemboli. Microemboli occur spontaneously in various clinical situations but their clinical impact and possible therapeutical implications are still under debate. This article provides a review of the actual literature concerning the current state of technical and clinical aspects of microembolus detection.

Increased circulating platelet-leucocyte complexes and platelet activation in patients with antiphospholipid syndrome, systemic lupus erythematosus and rheumatoid arthritis

It is possible that platelet activation may play a pathogenic role in the increased risk of thrombosis associated with antiphospholipid antibodies (APA). In this study, levels of in vivo platelet activation were measured in 20 patients with primary antiphospholipid syndrome (PAPS) and 30 systemic lupus erythematosus (SLE) patients (14 of whom had secondary APS) using sensitive flow cytometry. Soluble P-selectin levels were also assayed. Platelet CD63 expression was significantly higher in PAPS than normal controls (P = 0.007), as well as SLE patients with and without secondary APS (P = 0.03 and P = 0.002 respectively). PAC-1 binding was significantly higher in PAPS than the control group (P = 0.007) and SLE patients without APS (P = 0.015). Platelet-leucocyte complexes were significantly higher in SLE patients than both PAPS and the control group, and platelet-monocyte complexes were significantly increased in PAPS compared with the control group. (Platelet-leucocyte complexes were also significantly higher than controls in 10 rheumatoid arthritis (RA) patients without APA). Soluble P-selectin levels were significantly higher in PAPS and SLE patients than the control group. Platelet CD62p expression, annexin V binding and platelet microparticle numbers were not increased in PAPS or SLE patients. We conclude that there is evidence of increased platelet activation in PAPS and SLE, and this is important to note as it may have potential therapeutic implications with respect to use of antiplatelet agents in these patients.

Antiphospholipid (Hughes) syndrome in systemic lupus erythematosus

APS is found in 20% to 35% of patients with SLE. PAPS and secondary APS have similar features and aPL specificities. The clinical course of the secondary syndrome is independent of the activity and severity of lupus, but the presence of APS worsens the prognosis of patients with lupus. Some features of SLE may result from thrombosis in patients with APS; thus, these patients require anticoagulation rather than corticosteroids. Novel preliminary classification criteria for APS were formulated during a postconference workshop held in Sapporo, Japan, following the Eight International Symposium on Antiphospholipid Antibodies. Treatment of APS remains empirical because of limited controlled prospective data. There is strong evidence that patients with aPL-associated thrombosis are subject to recurrences and require prophylactic therapy. APS is a treatable cause of recurrent fetal loss in women with SLE. The treatment of choice is anticoagulation with heparin, either standard unfractionated heparin or LMWH. One of the main reasons for the improving outcomes in APS pregnancies is closer obstetric surveillance.