Heyde's syndrome

Overview
Heyde's syndrome is a syndrome of aortic valve stenosis associated with gastrointestinal bleeding from colonic angiodysplasia. It is named after Dr. Edward C. Heyde, who first described the association in 1958.

Signs and symptoms
Aortic valve stenosis is a cause of heart failure and several other cardiac problems. In most patients, however, it goes unsuspected. A number of patients develop a bleeding tendency resembling that of platelet-derived coagulation problems, e.g. nosebleeds, bruising. Some bleed from angiodysplasias (small vascular malformations) of the colon. This can be subtle, causing mild anemia, or serious, warranting blood transfusions and surgery to control bleeding.

Diagnosis
Angiodysplasias are usually identified on colonoscopy. In some patients, the cause of bleeding cannot be identified on colonoscopy, and only angiography of the colonic vasculature can identify the location of the angiodysplasias.

Aortic valve stenosis is identified on echocardiography (ultrasound studies of the heart), where a decreased Orifice Area of the aortic valve implies stenosis.

Routine testing for Von Willebrand disease (see below) generally fails to identify the coagulation abnormality, as only the high-molecular weight-multimers (HMWM) of von Willebrand factor are decreased. Only dynamic platelet function analysis (PFA) might be of some use in this respect.

Pathophysiology
In the 45 years following its initial description, no plausible explanations could be found for the association between aortic valve stenosis and gastrointestinal bleeding. Indeed, the association itself was questioned by a number of researchers. A number of reports stressed, however, that replacement of the diseased aortic valve often led to resolution of the coagulopathy.

Warkentin et al (1992) proposed that the link between aortic stenosis and bleeding was due to a mild form of von Willebrand disease. Some later reports confirmed the suspicion, including a 2002 study by the same group that showed resolution of the coagulation abnormality after aortic valve replacement.

In 2003 a study by Vincentelli et al finally gave an explanation for the remarkable phenomenon. It showed how the subtle form of von Willebrand disease present in Heyde syndrome patients resolved rapidly after heart valve replacement of the stenosed aortic valve. The coagulation abnormality, the study poses, is possibly caused by the increased breakdown of the very large von Willebrand factor molecule by its natural catabolic enzyme (named ADAMTS13) under conditions of high shear stress around the valve.

Therapy
Symptomatic treatment can be given in the form of blood transfusions. Desmopressin (DDAVP) releases Factor VIII storage pools and is used in mild to moderate cases of von Willebrand disease. Other approaches, including estrogen therapy, are discussed in the angiodysplasia article.

Vincentelli et al argue that severe forms of Heyde's syndrome might be sufficient reason for aortic valve replacement, even if the stenosis is otherwise clinically unimportant and is not likely to cause complications.

History
The syndrome was originally described in 1958 by Dr Edward C. Heyde, an internist living and working in Vancouver, WA in a letter to the New England Journal of Medicine. He reported ten patients with the association.

The statistical association was proven before there was any clue why patients with aortic valve stenosis had a higher occurrence of colonic bleeding. Already in 1958, a letter in the New England Journal of Medicine (Goldman et al) reported an odds ratio of almost 3.0 between the two diseases.