Aortocardiac Fistula

Aortocardiac Fistula



Basic Information  image



Definition


An aortocardiac fistula is a defect in the wall of the aorta at the right aortic sinus. The defect can take the form of a tract dissecting through the aortic ring to the right ventricle (RV), right atrium (RA), or interventricular septum (IVS), or it may occur from aneurysmal dilation of the right aortic sinus (or more rarely in the noncoronary portion of the sinus) rupturing in the RA or RV or creating tracts dissecting through the myocardial septum.



Synonym(s)




• Aortic root rupture


• Ruptured aortic sinus aneurysm


• Tear of the aortic root



Epidemiology



Species, Age, Sex


More common in middle-aged and older stallions, although it may affect geldings and mares as well



Disease Forms/Subtypes




• Acute rupture


• Sudden death

• Distress, ventricular tachycardia, and right-sided murmur

• Subacute or chronic: Right-sided continuous murmur


• Fistula opening in the RV or RA: Severe RA and RV volume overload leading to right-sided heart failure

• Fistula dissecting down into the IVS: Form subendocardial tract along the septum that may rupture into RV, LV, or both, causing RV or LV volume overload


History, Chief Complaint




• Acute distress sometimes mistaken for abdominal pain: Restlessness, sweating, and recumbency


• Exercise intolerance


• A murmur detected during routine examination


• Sudden death



Physical Exam Findings




• Extreme distress


• Right-sided, loud, continuous murmur


• Tachycardia


• Rapid, weak arterial pulses with pulse deficits


• Bounding arterial pulses


• Jugular venous pulses


• Tachypnea



Etiology and Pathophysiology




• May be congenital or acquired


• A congenital sinus of Valsalva aneurysm is the underlying defect that precedes aortic rupture in some cases. The defect is believed to be an absence of the tunica media of the aorta in the area of the right sinus of Valsalva (see “Aortic Aneurysm” in this section).

• May be an acquired lesion caused by increased intraaortic pressure that occurs during strenuous exercise such as racing or breeding in stallions that could be coupled with preexisting degeneration of the aortic media.

• Degenerative aortic medionecrosis may predispose to aortic ring rupture.

• Aortic rupture into the right side of the heart usually causes severe right heart overload, leading to right heart failure.


• Aortic rupture dissecting through the ventricular septum causes widespread damage to the cardiac conduction system, resulting in rhythm disturbances (usually monomorphic ventricular tachycardia).

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  4. Cervix, Defects of

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Jul 24, 2016 | Posted by in SMALL ANIMAL | Comments Off on Aortocardiac Fistula

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