DISCUSSION
Although described in the 1950s by Dr, Edward Heyde, as the combination of calcific aortic stenosis and iron deficiency anemia resulting from gastrointestinal bleeding. Heyde syndrome now refers to a triad of aortic stenosis, acquired coagulopathy (von Willebrand syndrome type 2A, abbreviated here vWS-2A) and anemia due to bleeding from intestinal angiodysplasia or an idiopathic site4. The definitive pathophysiology of Heyde Syndrome has yet to be agreed upon. Currently, the most widely accepted one is the acquired deficiency of von Willebrand factor due to high shearing stress due to the flow of blood through the narrowed valve as in conditions such as aortic Stenosis5. The high shearing force leads to a significant conformational change in the high- molecular-weight (HMW) von Willebrand factors (vWF) which enables the A2 domain of vWF to be degraded by ADAMST13, a well-known plasma protease. The resulting HMW vWF multimers are less effective in coagulation and are cleared away easily which leads to the development of acquired Von Willebrand factor deficiency.5,6 Even though the pathophysiology of the development of Acquired VWF deficiency (AVWS) is well laid out, a study of case reports has found that almost 65 % of the cases didn’t develop AVWS. Thus, other modalities of pathophysiology should be explored1.
Angiodysplasia in the Gastrointestinal tract as described in the original triad should also be taken into consideration as a potential source of bleeding in adjunction to the acquired VWF deficiency. The available literature on Heyde syndrome suggests that the site most common for the development of angiodysplasia was the small intestine with jejunum in particular whereas the site most common for development of isolated angiodysplasias is caecum. This may hint towards different pathogenesis of angiodysplasia in Heyde syndrome and also highlights the importance of examining the jejunum and small intestine.1 AVWS may potentially be a factor in the development of angiodysplasias.7
In an elderly patient with established aortic stenosis, if there is development of iron deficiency anemia, Heyde syndrome should be kept in consideration4. One of the challenges of diagnosing a case such as Heyde syndrome is establishing the connection between arteriovenous malformation (AVM) and aortic stenoses. The evidence that aortic stenosis is the root cause of coagulopathy is much stronger than the evidence for a causal association with angiodysplasia8. However, one study demonstrates that AS is substantially more common in individuals with concurrent AVMs and that the stenoses are more severe, which may have an impact on how both AVMs and AS are managed. Since there may be changes in how patients with a recognized Heyde syndrome are managed, current studies likely underestimate the true prevalence of the Heyde syndrome9.
Our patient had a history of recurrent GI bleeds requiring blood transfusions. Similar findings have been reported from other studies indicating Heyde disease as having a high risk of bleeding and subsequent mortality requiring urgent interventions.10Patients with Heyde syndrome who are treated by intestinal resection generally continue to bleed from other sites, while AVR usually cures clotting disorder and anemia. Although aortic valve replacement is the mainstay of treatment in Heyde syndrome, newer interventions such as TAVI (Transcatheter Aortic Valve Implantation) have been found to durably reduce the events of Gastrointestinal bleeds in Heyde syndrome11. As the recurrence rate was significant during follow-up, a possible association with residual PVL (Paravalvular Leakage) requires further investigation to improve treatment options and outcomes in patients with HS12. Episodes of severe bleeding may necessitate blood transfusions and emergency bowel resections.
In our case, aorto-atrial fistula was noted on TTE with a paravalvular leak from the previous repair of aortic stenosis. Aorto-atrial fistulas are infrequent but have the potential to be life-threatening by creating excessive burden on the heart’s volume. They occur when an abnormal connection develops between the structures of the aorta and the cardiac atria. The diagnosis of AAFs is frequently delayed due to the non-specific nature of the symptoms presented, and the sensitivity of trans-thoracic echocardiography (TTE) is only around 50%.13 The aorto-atrial fistula usually is caused as a sequela of endocarditis, congenital causes and rarely as a complication of cardiac surgery13. In recent years, there has been an increasing utilization of percutaneous closure for Atrial-Arterial Fistulae (AAF). Although there are no dedicated devices designed exclusively for transcatheter closure of fistulas, devices that are primarily intended for closing atrial septal defects, have shown its effectiveness for this application. The overall success rates for the treatment are at least 70%, albeit with a mortality rate of approximately 15%14.