Patent foramen ovale in patients with sickle cell disease and stroke: case presentations and review of the literature

Association Between Patent Foramen Ovale and Overt Ischemic Stroke in Children With Sickle Cell Disease

Ischemic stroke is one of the most devastating complications of sickle cell anemia (SCA). Previous studies have shown that intracardiac shunting including patent foramen ovale (PFO) can be a potential risk factor for stroke in children with SCA. This study investigates the association between PFO and overt ischemic stroke in the DISPLACE (Dissemination and Implementation of Stroke Prevention Looking at the Care Environment) study cohort of 5,247 children with SCA of whom 1,414 had at least one clinical non-contrast transthoracic echocardiogram. Presence of PFO was taken from the clinical report. Further, we assessed the association between PFO and other clinical and hemolytic factors in children with SCA such as history of abnormal sickle stroke screen [elevated Transcranial Doppler ultrasound (TCD) velocity] and patient's baseline hemoglobin. In 642 children for whom all data were available, the adjusted odds ratio (OR) for overt stroke was higher in those with PFO but this was not statistically significant (OR: 1.49, 95% CI: 0.20-11.03, p = 0.6994). With an OR of 0.85, the study suggested less PFOs in those with abnormal TCD, but this was not statistically significant (95% CI: 0.17-4.25, p = 0.8463). Overall, the prevalence of PFO in this large sub study of non-contrast echocardiography amongst children with SCA is much lower than previous smaller studies using bubble contrast echocardiography. Overt stroke was non-statistically more common in children with SCA and PFO, but there was no evidence that PFO was more common in those with abnormal TCD, the most important pediatric sickle stroke screen.

Stroke and presence of patent foramen ovale in sickle cell disease

Sickle cell disease (SCD) is an inherited monogenic hemoglobinopathy characterized by formation of sickle erythrocytes under conditions of deoxygenation. Sickle erythrocytes can lead to thrombus formation and vaso-occlusive episodes that may result in hemolytic anemia, pain crisis and multiple organ damage. Moreover, SCD is characterized by endothelial damage, increased inflammatory response, platelet activation and aggravation, and activation of both the intrinsic and the extrinsic coagulation pathways. Cerebrovascular events constitute an important clinical complication of SCD. Children with SCD have a 300-fold higher risk of acute stroke and by the age of 45 about 25% of patients have suffered an overt stoke. Management and prevention of stroke in patients with SCD is not well defined. Moreover, the presence of patent foramen ovale (PFO) increases the risk of the occurrence of an embolic cerebrovascular event. The role of PFO closure and antiplatelet or anticoagulation therapy has not been well investigated. Moreover, during COVID-19 pandemic and taking into account the increased rates of thrombotic events and the difficulties in blood transfusion, management of SCD patients is even more challenging and difficult, since data are scarce regarding stroke occurrence and management in this specific population in the COVID-19 era. This review focuses on pathophysiology of stroke in patients with SCD and possible treatment strategies in the presence of PFO.

Diverse manifestations of a sickle cell crisis

We describe the case of a 21-year-old man with a background of sickle cell disease (SCD) who was on acute presentation in a sickle cell crisis required immediate intensive care admission with red blood cell exchange and ventilatory support. He had right frontal lobe infarcts and extensive bilateral deep white matter lesions most likely secondary to fat embolism. Inpatient investigations demonstrated a patent foramen ovale, explaining the route of spread of the fat embolus. He then had a transcatheter closure of the atrial defect. The patient needed prolonged inpatient rehabilitation. He was discharged from hospital in a wheelchair secondary to severe lower limb neurology and bilateral knee heterotopic ossification. He lives with the possibility of early onset dementia and cognitive decline, requiring constant care. The case highlights the multiple manifestations of SCD and their diverse and debilitating consequences.

Vascular Instability and Neurological Morbidity in Sickle Cell Disease: An Integrative Framework

It is well-established that patients with sickle cell disease (SCD) are at substantial risk of neurological complications, including overt and silent stroke, microstructural injury, and cognitive difficulties. Yet the underlying mechanisms remain poorly understood, partly because findings have largely been considered in isolation. Here, we review mechanistic pathways for which there is accumulating evidence and propose an integrative systems-biology framework for understanding neurological risk. Drawing upon work from other vascular beds in SCD, as well as the wider stroke literature, we propose that macro-circulatory hyper-perfusion, regions of relative micro-circulatory hypo-perfusion, and an exhaustion of cerebral reserve mechanisms, together lead to a state of cerebral vascular instability. We suggest that in this state, tissue oxygen supply is fragile and easily perturbed by changes in clinical condition, with the potential for stroke and/or microstructural injury if metabolic demand exceeds tissue oxygenation. This framework brings together recent developments in the field, highlights outstanding questions, and offers a first step toward a linking pathophysiological explanation of neurological risk that may help inform future screening and treatment strategies.

Megestrol Acetate Induced Paradoxical Embolism in a Sickle Cell Disease Patient

We report a case of a 43-year-old African American female patient with otherwise stable sickle cell disease (SCD) in which use of megestrol acetate for appetite stimulation quickly potentiated her prothrombotic state within just a few days. This resulted in infarcts involving the bilateral cerebral hemispheres suggestive of embolic infarcts and the patient was subsequently confirmed to have a patent foramen ovale (PFO). A widespread literature search in PubMed revealed that this is a rare case in the literature and that the effects of megestrol acetate use in patients with SCD have not been well studied. Future research should focus on the risks of initiating megestrol acetate therapy to develop an advanced risk assessment algorithm in patients with SCD as the risk of thromboembolism may far outweigh the potential benefits.

How I treat and manage strokes in sickle cell disease

Neurologic complications are a major cause of morbidity and mortality in sickle cell disease (SCD). In children with sickle cell anemia, routine use of transcranial Doppler screening, coupled with regular blood transfusion therapy, has decreased the prevalence of overt stroke from ∼11% to 1%. Limited evidence is available to guide acute and chronic management of individuals with SCD and strokes. Current management strategies are based primarily on single arm clinical trials and observational studies, coupled with principles of neurology and hematology. Initial management of a focal neurologic deficit includes evaluation by a multidisciplinary team (a hematologist, neurologist, neuroradiologist, and transfusion medicine specialist); prompt neuro-imaging and an initial blood transfusion (simple followed immediately by an exchange transfusion or only exchange transfusion) is recommended if the hemoglobin is >4 gm/dL and <10 gm/dL. Standard therapy for secondary prevention of strokes and silent cerebral infarcts includes regular blood transfusion therapy and in selected cases, hematopoietic stem cell transplantation. A critical component of the medical care following an infarct is cognitive and physical rehabilitation. We will discuss our strategy of acute and long-term management of strokes in SCD.