Dynamic Left Main Coronary Artery Obstruction Associated With Williams Syndrome
A 5-year-old boy with Williams syndrome (WS) presented with a history of diffuse recurrent obstructive vascular disease. At the age of 12 months, he underwent pericardial patch augmentation of the ascending aorta and pulmonary arteries. He subsequently required Dacron patch repair of the ascending aorta and aortic arch at 3 years of age. In the interim, he had undergone percutaneous transluminal angioplasty and stenting for recurrent peripheral pulmonary artery stenoses and aortic recoarctation. On routine follow-up, he was found to have worsening right ventricular hypertension associated with disparate lung perfusion on a nuclear perfusion scan. He was brought to the catheterization laboratory for further investigation. Angiography showed recurrent pulmonary artery in-stent restenosis and aortic recoarctation. Coronary angiography demonstrated a 30% ostial right coronary stenosis and a 75% dynamic left main coronary artery (LMCA) stenosis (Figure 1 and Movie I of the online-only Data Supplement). Intravascular ultrasound was performed to further evaluate the LMCA stenosis before anticipated revascularization. After administration of intracoronary nitroglycerin, intravascular ultrasound was performed with a 2.5F Atlantis SR Pro 40-MHz catheter (Boston Scientific, Natick, Mass) by automatic pullback at 0.5 mm/s. Intravascular ultrasound revealed dynamic contraction of the LMCA without evidence of fixed obstruction (Figure 2 and Movie II of the online-only Data Supplement). Quantitative intravascular ultrasound analysis demonstrated a reduction in arterial lumen cross-sectional area from 14.8 mm2 in diastole to 3.7 mm2 in systole, thus indicating a 75% dynamic obstruction. Although there is no consensus on the cross-sectional area at which LMCA obstruction is considered critical, in adult patients an absolute area >9 mm2 is thought to be adequate for normal arterial supply.1 Because most of the epicardial flow occurs during diastole, the diastolic measurements of the LMCA are likely more relevant. The patient had no history of chest pain or myocardial infarction. On the basis of the dynamic nature of the obstruction and the widely patent diastolic lumen, no further coronary intervention was deemed necessary. The patient remained asymptomatic at the 5-year follow-up.
WS is a multisystem disorder caused by microdeletion of chromosome 7 encompassing the elastin gene. Patients with WS have the hallmark features of generalized arteriopathy, presenting as stenoses of medium and large arteries and hypertension. The prevalence of any cardiovascular disease ranges between 53% and 100% of patients with WS, and many patients have multiple cardiovascular involvements.2 Cardiovascular manifestations of WS affect predominantly the supravalvular aorta and pulmonary regions. Coronary artery inflow can be restricted because of thickening of the aortic or sinus wall, obstructing the coronary orifice. Coronary arteries in WS also are subjected to elevated prestenotic systolic pressure, resulting in dilatation and tortuosity and promoting premature arteriosclerosis. Dynamic coronary obstruction is most commonly caused by intramyocardial muscle bridging; however, this is unlikely to be the cause of obstruction of the LMCA because it is an extramyocardial structure. The dynamic change observed in the LMCA of our patient is consistent with structural changes seen in elastin arteriopathy associated with WS.2
The online-only Data Supplement is available at http://circ.ahajournals.org/cgi/content/full/120/2/181/DC1.