Persistent Thebesian Sinusoids Presenting as Ischemic Heart Disease
A 54-year-old man with no significant past medical history or modifiable cardiovascular risk factors was admitted with chest pains and palpitations. ECG revealed atrial fibrillation with fast ventricular response that reverted to sinus rhythm after intravenous administration of digoxin. His 12-hour troponin I level was marginally elevated (0.07 ng/mL; normal range <0.06 ng/mL). Subsequent serial 12-lead ECGs (Figure 1) demonstrated widespread dynamic ST-segment and T wave changes. The patient was treated for an acute coronary syndrome and became pain free on intravenous administration of glyceryl trinitrate and glycoprotein IIB/IIIA antagonist. Coronary angiography demonstrated pristine epicardial coronaries but a bizarre appearance of capillary blush draining into the left venticular cavity, during both left main stem and right coronary artery injection (Figure 2A and 2B and Movie I and II). In absence of any myocardial tumor, ventricular hypertrophy, or evidence of noncompaction (normal contrast echocardiogram, not shown), this appearance suggests prominent thebesian sinusoids communicating between the coronary arteries and the ventricle. The patient completed a symptom-free exercise test to 8 metabolic equivalents (albeit with dynamic ST depression) and remains asymptomatic and in sinus rhythm 6 months after the index admission.
In the beginning of the 18th century, Raymond Vieussens and Adam Christian Thebesius first described the vasa cordis minimae, today known as vasa Thebesii, Thebesian sinusoids, or venae cordis minimae. These primitive vessels precede coronary arteries as nutrient suppliers in the embryonic heart. Endothelium-lined sinusoids protrude from the cavity of the developing ventricle, which join up with inter-trabecular spaces. As heart muscle develops, the outer intertrabecular spaces (initially large and extending to the epicardium) narrow into capillaries and communicate with the developing coronary vessels. The inner intertrabecular channels remain contiguous with the ventricular cavity, becoming the Thebesian vessels.1
Coronary artery fistula is a rare congenital anomaly, with a reported incidence of 0.08% to 0.3% in the adult population referred for cardiac catheterization.2 Communication of all 3 coronary arteries to the left ventricle is extremely rare. Two types of anatomocoronarographic appearances have been described: conduit coronary artery fistulae and microfistulae.3 The former tend to be large shunts occasionally presenting with signs of heart failure, whereas anginal symptoms are common in the latter. Absence of a diastolic murmur and left ventricular hypertrophy may be surrogate indicators of small shunt volume.2
Three levels of coronary (left) cameral (left–left) shunting are noted: (1) the arterial luminal type (the most common), in which a conduit coronary artery enters the cardiac chamber directly; (2) the arteriosinusoidal type, in which communication is through a myocardial sinusoidal network; and (3) the arteriocapillary type, in which the arterial vessel drains into the capillaries.2 The former 2 bypass capillaries and may give rise to myocardial ischemia by a mechanism of coronary steal, as the normal circulation offers a greater resistance to flow than the fistula.2 The intracoronary diastolic perfusion pressure diminishes in proportion to the size of the fistula. The myocardium downstream of the fistula is at risk of ischemia, especially after exercise.4 An elegant study from Luebeck measured lactate levels from the coronary sinus in 8 patients with multiple coronary artery–left ventricle fistulae and normal epicardial coronary arteries.2 After bursts of atrial pacing, patients developed anginal symptoms, ST-segment changes on the surface ECG, and myocardial hypoxia was confirmed by elevated coronary sinus lactate levels.
Large single fistulae may be amenable to surgical correction or coil embolization; small multiple fistulae are managed medically. Conflicting evidence from case reports exists about the benefits of medical therapy. Nitrate therapy may exacerbate ischemia by increasing leakage to the left ventricle.4 We decided not to offer pharmacotherapy to our patient who had an arteriosinusoidal coronary cameral fistula, as he did not have symptoms on exercise or significant coronary disease on angiography.
The online-only Data Supplement, which contains Movies I and II, is available with this article at http://circ.ahajournals.org/cgi/content/full/ 117/16/e315/DC1.