Discussion
A CAF is defined as an abnormal communication between one of the
coronary arteries and a cardiac chamber o or another blood vessel. CAFs
are present in 0.2% of patients undergoing diagnostic cardiac
catheterization. (8)
The right and left coronary arteries are involved in 55 and 35% of
cases, respectively, with the involvement of both vessels in just 5% of
cases. (2) The arteries serve as a shunt between the coronary system and
the cardiac chamber into which they drain. Large shunts may present with
pulmonary edema, pulmonary hypertension, infective endocarditis,
rupture, or thrombosis of the fistula, and associated arterial aneurysm
or myocardial ischemia distal to the fistula (‘myocardial steal
phenomenon’). (9)
There are several possible reasons why CAF may not be visualized
directly using transthoracic echocardiography. The CAF may be distally
positioned in the coronary circulation and could be of smaller caliber.
This can make them much more difficult to detect, particularly during
ventricular systole. However, it is possible to visualize them with
contrast when a higher MI (Mechanical Index) is used. This supports the
visualization of both the myocardial tissue and the contrast agent
simultaneously.
Contrast agents (including SonoVue) have been reported previously as
safe for direct coronary artery injection. It has been used safely
during septal ablation in patients with hypertrophic obstructive
cardiomyopathy (14). These agents have a good safety profile for use in
both cardiac and abdominal ultrasound applications. The incidence of
severe adverse reactions to ultrasound contrast agents is no greater and
may be lower than that reported for the contrast agents commonly used in
other cardiac imaging tests. (8)
Previously, CAF has been diagnosed with aortography, (10) coronary
angiography, (11), and coronary CT. (13) Although there has been a case
of color Doppler assessment of a CAF, (12) we cannot readily confirm
them with echocardiography. In this study, we employed a new and simple
diagnostic approach for CAF using a contrast agent. This assisted with
the diagnosis, because it clarifies typical turbulence flow, as it
appears in the left ventricle. The use of intraprocedural contrast
echocardiography results in an improved procedure and thereby patient
outcomes, by shortening the procedure and fluoroscopy time. Contrast
echocardiography at the time of aortography proves extremely valuable in
both opacifying the coronary arteries and determining which chambers the
fistula connects to.
The value of localizing the site of drainage of the fistula is high to
the interventional cardiologist when attempting to close it.