Friday, November 19, 2010

Coronary anomalies




Classification:

  • Abnormal origin of the coronary arteries:
  • Anomalous pulmonary origin of the coronary arteries.
  • Origin of both coronary arteries from the right sinus of Valsalva.
  • Aneurysms of the coronary arteries.
  • Aneurysms of the sinuses of Valsalva.
  • Coronary Arterio-Venous fistula.
  • Anomalies of the coronary sinus:
  • Enlargement of the coronary sinus.
  • Absence of the coronary sinus.
  • Atresia of the coronary sinus.


Abnormal origin of the coronary arteries


1. Anomalous pulmonary origin of the coronary arteries


Pathology:
  • In most cases only the left coronary artery (LCA) arises from PA, while the right coronary artery (RCA) arises normally from AO. The course & branching of LCA are normal. The size of the coronary arteries is normal in the young, but they become dilated beyond infancy. This anomaly is called Bland-White-Garland syndrome.


Bland-White-Garland syndrome: 3D Volume Rendering CT of the heart demonstrating the origin of the Left Coronary Artery (LCA) from the Pulmonary Artery (PA) (in blue). The Right Coronary Artery (RCA) is normal (red).
http://www.gehealthcare.com/euen/cardiology/clinical-case/images/cardiac-ct-exam_big.jpg


  • Sometimes only RCA arises from PA.
  • Both coronary arteries rarely arise from PA.
  • Some patients have a single coronary artery, which is arising from PA.

Complications:
  • LV wall & papillary muscles show areas of scarring & calcification, and LV becomes dilated.
  • Endocardial fibroelastosis occurs.
  • MR may occur.


Pathophysiology:


During fetal life: while PA pressure is higher than AO pressure, the anomalous coronary artery gets anterograde flow from PA.
After birth, PA pressure drops:
If only one coronary artery is anomalous, blood flows from AO to the normally arising coronary artery, and then through collaterals to the anomalous one, and finally to PA, constituting a left-to-right shunt.
In 10 % of cases, the collaterals are extensive, there is no myocardial ischemia, and patients may survive to adult life. Even manifestations of a large Arterio-Venous shunt may develop.


Clinical picture:


Most patients present during the first few months of life with attacks of acute heart failure.
Angina-like symptoms in infancy, which might be explained as colic.
Few will present beyond infancy with chronic CHF.
MR may be present.
A soft continuous murmur of collaterals may occur at the upper left sternal border.
Sudden death may occur.


Chest x-ray:


Marked cardiomegaly, with LV & LA enlargement.
Pulmonary edema.
Left lower lobe lung collapse from bronchial compression may be found.


Electrocardiogram:


Infarction pattern.
Arrhythmias.


Echocardiography:


LV dilatation and areas of hypokinesia & akinesia.
LA dilatation.
Origin of the anomalous coronary artery from PA may be detected.
Doppler & color-Doppler may reveal the retrograde flow in the anomalous artery going to PA.


Myocardial perfusion imaging:


It shows areas of diminished or absent perfusion, distinguishing the case from idiopathic dilated cardiomyopathy.


Cardiac catheterization:


O2 step-up at PA level, if there is enough retrograde flow.
Increased PA pressure & pulmonary capillary wedge pressure (PCWP).
Aortography & coronary angiography will show the anomaly and the collaterals, with opacification of PA.


Natural history:


When both coronary arteries are anomalous, or when there is a single coronary artery and it is anomalous, prognosis is extremely poor. Death almost always occurs early. They have not been corrected surgically.
When only the left coronary artery is anomalous, prognosis is relatively better. Again early death usually occurs from CHF & arrhythmia.
Anomalous origin of the right coronary artery only carries the best prognosis.


Medical management:


Control of CHF.
Control of arrhythmias.
Treatment of myocardial ischemia & infarction.


Surgical management:

  • Infants with evidence of myocardial ischemia and no significant shunt need:
    • Re-implantation of the anomalous artery into the AO, or
    • A graft to anastomose the anomalous artery to the AO or to the subclavian artery, or
    • Creation of an Aortico-pulmonary window delivering blood from AO to the anomalous artery, and re-constructing PA.
  • Infants with ischemia and big shunt may be managed by simple ligation of the anomalous artery at its origin from PA.
  • Infants without myocardial ischemia and with good shunt: Operation may be delayed as long as possible.
  • Aneurysmectomy, may be needed.
  • Mitral valve replacement, may be needed.


Origin of both coronary arteries from the right sinus of Valsalva


The left coronary artery arises anterior to the right artery, penetrates the epicardium, turns sharply to the left usually passing behind PA, and then branches normally.
If it passes anterior to PA, it is clinically insignificant.
Sudden death during exercise has been reported.
Surgery is indicated in symptomatic cases.
Sometimes only the left anterior descending or the circumflex artery arises from the right aortic sinus, with the right coronary artery. These conditions are usually clinically insignificant.



Operative repair of anomalous left coronary artery (LCA) from the right sinus of Valsalva. The slitlike anomalous origin of the left coronary artery from the right aortic sinus of Valsalva is demonstrated, as is the intramural course of the coronary artery. (B) The intramural course of the artery is unroofed, placing the functional ostium in the left sinus. (C) Tacking sutures are used to secure the intima of the new coronary ostium and to reinforce the adjacent commissure of the aortic valve.
http://img.medscape.com/pi/emed/ckb/pediatrics_cardiac/889392-895854-3087.jpg



Coronary arterial aneurysms


Congenital localized aneurysms of the coronary arteries are due to medial dysplasia, and may be multiple.
They are more common in RCA.
Thrombosis can occur, with occlusion of the parent artery or embolism downstream.
They are also liable to rupture.
Clinically: systolic & diastolic murmurs may be found.
Symptomatic cases need CABG.


Sinus of Valsalva aneurysm


Definition:


Aneurysmal dilatation of the aortic sinuses, which may be congenital or acquired.


Anatomy:


Immediately above the orifice of the aorta, the aortic wall bulges to form the aortic sinuses (Sinuses of Valsalva), one above each cusp of the aortic valve.
The anterior sinus is called the right coronary aortic sinus, from which the right coronary artery arises.
The left posterior one is called the left coronary aortic sinus, from which the left coronary artery arises.
The right posterior one is the non-coronary aortic sinus.


Pathology:


These aneurysms are due to weakness at the union of the aorta with the left ventricle. The aortic media may separate from the aortic annulus and retract upwards. The structure in-between becomes aneurysmal and may rupture.
The usual sites are:
Aneurysm of the right coronary aortic sinus is the commonest. It may rupture into RV infundibulum.
Aneurysm of the non-coronary aortic sinus is the next common. It may rupture through the atrial septum into the left atrium.
Aneurysm of the left coronary aortic sinus is the least common. If ruptured it will be into the pericardium, but to the best of our knowledge, this was not reported. It may compress the left coronary artery.


Associated conditions:


Aneurysm of the right coronary aortic sinus is associated with infundibular VSD in 50 % of cases.


Clinical picture of unruptured aneurysm:


Unruptured aneurysms are generally asymptomatic but a few cases have been reported to cause:
Tricuspid regurgitation, due to aneurysm of the non-coronary aortic sinus.
Pulmonary stenosis, due to aneurysm of the right coronary aortic sinus.
Rarely, myocardial ischemia, due to coronary artery compression.
Aortic regurgitation may occur due to dilated aortic annulus.


Clinical picture of ruptured aneurysm:


Rupture occurs mostly in adults. It may occur spontaneously or secondary to infective endocarditis. It may be slow or rapid.
Slow rupture results into a small left-to-right shunt.
Rapid rupture results into a big left-to-right shunt, with:
Tearing mid chest pain.
Dramatic onset of acute pulmonary plethora.
A loud continuous murmur accentuating in diastole, heard along the left sternal border lower down than that of PDA, and associated with a thrill.


Chest x-ray:


In ruptured aneurysms: Similar to PDA.


Electrocardiography:


Biventricular enlargement.
First & second-degree heart block, due to AV nodal compression.


Cardiac catheterization:


Aortography is diagnostic.
Pressure gradient across RV outflow tract may be detected, if the right coronary sinus is involved.


Natural history:


With small shunts, the major risk is infective endocarditis.
Extension of rupture may result in increasing shunt.
With large shunts, there is rapid CHF, which may lead to rapid death.


Medical management:


Treatment & prophylaxis of infective endocarditis.
Treatment of CHF.


Surgical management:


Indications:
  • All ruptured cases.
  • Presence of TR or PS, with or without rupture.

Procedures:
  • Repair: better done via aortotomy. The orifice is obliterated with suture or a Dacron patch.
  • Infundibular VSD should be sought and closed.
  • Aortic valve replacement may be needed, if AR is present.
  • Infundibular resection may be needed, in presence of infundibular PS.
  • Tricuspid repair may be needed.


Coronary arteriovenous fistula


Pathology:


There is one or more communications between one or more coronary arteries and one or more venous channel.
The right coronary artery is affected more.
Termination of the fistula may be in: Coronary sinus, RV, P. trunk, right and/or left PA.

Complications include thrombosis, rupture, myocardial ischemia and endocarditis may occur.


Clinical manifestations:


Symptoms: Patients may be asymptotic. If the left-to-right shunt is big enough, it can cause CHF, which may occur during the 1st year of life, or after age 40 years.

Sings: Cardiomegaly is usually detected. Continuous murmur may be heard in unusual locations.


Investigations:

  • Chest x-ray: May show cardiomegaly & pulmonary plethora.
  • ECG: RVH may be found.
  • Cardiac catheterization:
    • O2 step-up at the site of termination may be found.
    • Selective coronary angiography demonstrates the pathology.


Management:


Medical management: Prevention & treatment of complications.
Surgical management: Fistulae should be obliterated by sutures if small, or by Dacron or pericardial patch if large.


Coronary sinus anomalies


Significance:


In general, coronary sinus anomalies have no clinical significance, apart from the technical difficulties during cardiac catheterization and open-heart surgery.


Causes of enlargement of the coronary sinus:

  • Persistent left SVC draining into the coronary sinus. The left SVC may be also draining the IVC that unites with the Azygos or Hemi-Azygos vein, thus further increasing the return to the coronary sinus.
  • Coronary arterial-coronary sinus fistula.
  • Left atrial-coronary sinus communication.
  • Pulmonary venous-coronary sinus communication.


Absence of the coronary sinus:


This occurs in Raghib’s complex that consists of a triad of:
  • Absence of the coronary sinus.
  • Coronary sinus ASD.
  • Persistent left SVC draining into LA.


Atresia of the coronary sinus:


In these cases the cardiac venous return reaches the atria through:
  • Communication between the coronary sinus & left SVC, draining into left innominate vein to right SVC to RA.
  • Or, multiple connections between the coronary sinus & the atria.

It may be associated with other cardiac anomalies.

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