Coronary Steal Resulting from LIMA-to-SVG-to-LAD-to-Ventricular Fistula Physiology Associated with Malpositioned Prosthetic Aortic Valve

Case Report. A 47-year-old woman presented to our institution with unstable angina. Her past medical history included hypertension, dyslipidemia, bicuspid aortic valve stenosis and ascending aortic aneurysm. Three years prior she had undergone aortic valve replacement with a mechanical St. Jude valve and aortic root graft repair at an outside facility. The procedure had been complicated by hemodynamic compromise requiring emergent saphenous vein graft (SVG) bypass to the left anterior descending (LAD) artery. Six weeks post-operatively, the patient had a non-ST elevation myocardial infarction (NSTEMI) and was found during catheterization to have an occluded SVG to LAD ostium and underwent emergent left internal mammary artery (LIMA) bypass to the SVG.

At presentation to our institution, the patient’s serum troponin levels were within normal limits and her electrocardiogram revealed sinus rhythm with no ischemia. In light of her medical history and ongoing anginal symptoms, cardiac catheterization and coronary angiography were performed.

A 6 French (Fr) Judkins L4 catheter could not locate the left main (LM) within the aortic root (Figure 1). A 6 Fr Judkins R4 catheter positioned at the marker ring suggested that the SVG-LAD was occluded (Figure 2). Selective LIMA angiography revealed patent LIMA-SVG-LAD. The LIMA and SVG were hypertrophied, but distal to the SVG anastomosis, the LAD was atretic (Figure 3). The angiographic findings were suggestive of retrograde flow from the SVG-LAD anastomosis into the LM. Furthermore, the retrograde flow into the LM was seen to emerge into the left ventricular outflow tract almost continuously throughout the cardiac cycle. Transthoracic echocardiography confirmed the suspicion that the mechanical aortic valve had been positioned too high resulting in “ventricularization” of the LM.

We hypothesized that during the original AVR the malpositioned mechanical valve must have disrupted LM flow and resulted in hemodynamic compromise that was then treated by SVG bypass to the LAD. A subsequent NSTEMI may have resulted from a compromise to SVG flow and a LIMA-LAD was performed. The end-result was steal from the distal LAD, resulting in ischemia.

Redo sternotomy was performed and on cardiopulmonary bypass the old malpositioned valve was excised and replaced with a 21 mm On-X valve. Since her surgery, the patient has been asymptomatic.

Discussion. Coronary arterioventricular fistulas have been described,¹ as have coronary steal syndromes associated with coronary fistulae.^2,3 Cases of steal phenomena from LIMA grafts have also been reported.^4,5 However, to our knowledge, coronary steal associated with LIMA-SVG-LAD-LM-ventricle fistula physiology has not been previously described.

References

1. Sheikzadeh A, Stierle U, Langbehn AF, et al. Generalized coronary arterio-systemic (left ventricular) fistula. Case report and review of literature. Jpn Heart J 1986;27:533–544. 2. Kobayashi T, Yoshino T, Matsumura R, et al. Coronary steal in coronary artery-pulmonary artery fistula. Nippon Kyobu Geka Gakkai Zasshi 1988;36:2550–2554. 3. Cheng TO. Coronary steal in coronary artery to left ventricular fistula. Cathet Cardiovasc Diagn 1992;25:81. 4. Crowley SD, Butterly DW, Peter RH, Schwab SJ. Coronary steal from a left internal mammary artery coronary bypass graft by a left upper extremity arteriovenous hemodialysis fistula. Am J Kidney Dis 2002;40:852–855. 5. Ferreira AC, Marchena E, Liester M, Sangosanya AO. Internal mammary to pulmonary artery fistula presenting as early recurrent angina after coronary bypass. Arq Bras Cardiol 2002;79:181–182.