X-ray chest PA view in atrial septal defect with pulmonary hypertension

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The main pulmonary artery (MPA) is grossly dilated. The right pulmonary artery (RPA) is also quite enlarged. Right atrial enlargement is seen as a shift of the cardiac contour to the right of the spine. Pulmonary vascularity is increased and prominent end on vessels (End on) are also seen. Apex is upwards, suggesting a right ventricular configuration. All features suggest a large secundum atrial septal defect with a large left to right shunt producing severe pulmonary hypertension. Cardiomegaly on chest x-ray is suggestive of atrial septal defect in Eisenmenger syndrome, while it is unlikely in ventricular septal defect and patent ductus arteriosus. Cardiomegaly is mainly due to the grossly dilated right atrium in atrial septal defect. The right atrium is not enlarged in the other two varieties of Eisenmenger syndrome. In ventricular septal defect with large left to right shunt, the cardiac size comes down as pulmonary hypertension develops and the shunt decreases. Cardiomegaly in ventricular septal defect and patent ductus arterious with large left to right shunt are due to left ventricular enlargement. But this comes down with the development of pulmonary hypertension. That is why cardiomegaly is not a feature of Eisenmenger sydrome due to ventricular septal defect and patent ductus arteriosus. In patent ductus arterious, an additional feature on x-ray chest is the dilated aortic shadow. Inverted Y shaped ductal calcification may also be seen with patent ductus arteriosus and Eisenmenger syndrome.

X-ray chest PA view in atrial septal defect with pulmonary hypertension

Atrial septal defect with pulmonary hypertension

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X-ray chest PA view in atrial septal defect with severe pulmonary hypertension. Prominent main pulmonary artery, right pulmonary artery and left pulmonary artery (behind the main pulmonary artery) and end on views of dilated branch pulmonary arteries are seen. Echocardiography documented large secundum atrial septal defect (ASD) with severe pulmonary hypertension and bidirectional shunt across the ASD.

What is the importance of PR interval prolongation in secundum atrial septal defect (ASD)?

There is a higher incidence of sudden cardiac death (SCD) in familial ASD with prolongation of PR interval.

Crochetage sign in atrial septal defect

Crochetage sign in ASD

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Crochetage sign in atrial septal defect was described by Heller J et al [J Am Coll Cardiol. 1996 Mar 15;27(4):877-82] in 1996. It is a notch near the apex of the R wave in inferior leads. They noted a sensititvity of about 73% and specificity of 92% if the sign was present in all the three inferior leads. Early disappearance of the crochetage sign after surgical correction of atrial septal defect was found in 35% of cases even when the incomplete right bundle branch block (RBBB) pattern was persisting. The ECG illustrated above shows the notch at the apex of the R wave in leads II and aVF and a notch in the ascending limb of lead III.

This ECG also shows right atrial overload as evidenced by P wave amplitude of 0.3 mV in lead II. Incomplete RBBB pattern is seen as slurred S waves in lead I and rSrS pattern in V1.

Low atrial rhythm

Low atrial rhythm

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This ECG shows inverted P waves in inferior leads (II, III and aVF). This indicates that the atrial activation is spreading from below upwards. It is suggestive of a focus either in the low atrium or high junction. A mid junctional rhythm will have no visible P waves as the P wave will be within the QRS due to simultaneous activation of the atria and ventricles. In low junctional rhythm the P wave occurs after the QRS, in the ST segment and is inverted in inferior leads. In left atrial rhythm originating from the lower part, the P waves are inverted in inferior leads as well as lateral leads.

There is notching of the QRS complex in the inferior leads which suggest the crochetage sign in atrial sepatal defect. Low atrial rhythm can occur with sinus venosus atrial septal defect as the sinus node may be defective so that alternate focus arising in the low atrium gives the dominant rhythm. The PR interval is also shorter in low junctional and low atrial rhythm, more in the former than in the latter, due to obvious reasons.

ECG in atrial septal defect with severe pulmonary hypertension

Atrial septal defect with severe pulmonary hypertension

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ECG in atrial septal defect with severe pulmonary hypertension. rSR’ pattern is seen in V1 with a tall R’, possibly reflecting right ventricular hyperterophy. The strain pattern is extensive, from V1 to V6. RSR pattern is seen in III and aVF as well. The QRS duration is also increased. Echocardiogram in this case confirmed a large secundum atrial septal defect with severe pulmonary hypertension and bidirectional shunt.

ECG after surgical closure of ASD

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PR interval is prolonged and measures 280 msec. There is additional incomplete right bundle branch block with rSR’ pattern in V1 with a QRS width of 110 msec. This combination of first degree AV block with incomplete right bundle branch block is seen in familial atrial septal defect, which is transmitted in an autosomal dominant pattern. This means that 50% of first degree relatives have a chance to have atrial septal defect. In this individual there is no family history of atrial septal defect though a formal family study has not been done. Though this person had undergone surgical closure of the atrial septal defect three decades back, the abnormal ECG pattern is persisting.

Atrial septal defect (ASD)- colour Doppler echo

ASD on 2D echo

Echocardiographic image from subcostal four chamber view showing the atrial septal defect (ASD). Subcostal view is the ideal view for imaging atrial septal defect to exclude false echo dropouts which may be seen in apical four chamber view. This is because the imaging ultrasound beam is perpendicular to the septum in subcostal view while it is parallel the to the atrial septum in apical four chamber view. This ASD has good rims above and below, and could be suitable for device closure, which has to be decided after a trans oesphageal echocardiogram to assess all the rims.

ASD flow by colour Doppler

Colour Doppler flow mapping showing the red coloured flow across the atrial septum from left atrium (LA) to the right atrium (RA). The flow is red coloured because it is towards the echo transducer in this view. RV: right ventricle; LV: left ventricle. The flow reversal (blue colour and jet moving from RA to LA) can occur when there is severe pulmonary hypertension. Reverse flow across the atrial septal defect (right to left) can also be seen in total anomalous pulmonary venous connection.

Echocardiogram in ostium primum ASD with tricuspid regurgitation

Echocardiogram in apical four chamber view of primum ASD

Echocardiogram in apical four chamber view demonstrating a primum atrial septal defect (primum ASD). RV: right ventricle; LV: left ventricle; RA: right atrium; LA: left atrium; Primum ASD is part of the AV canal defect and is sometimes called a partial AV canal defect. In AV canal defects the atrioventricular septum (AV septum) is absent and both AV valves are at the same level. Primum ASD is usually associated with a cleft of the anterior mitral leaflet (AML) which appears like an additional commissure in the parasternal short axis view. Cleft AML produces significant mitral regurgitation, which is an association of ostium primum ASD. A similar defect in the tricuspid valve can cause tricuspid regurgitation. Another association of an ostium primum ASD is the inlet or canal ventricular septal defect (VSD).

Colour Doppler echocardiogram showing left to right shunt in ostium primum ASD

This frame with colour flow mapping demonstrates the left to right shunt (L>R Shunt) across the primum ASD. Though the actual direction of the shunt is perpendicular to the direction of the beam, most of the blood moves from the left atrium across the ASD towards the tricuspid valve in a direction which is parallel to the beam and towards the transducer. That is why this flow is encoded red.

Apical four chamber view showing tricuspid regurgitation in primum ASD

Apical four chamber view demonstrating tricuspid regurgitation (TR jet) in a case of primum ASD. The bluish mosaic coloured jet is due to the blood flowing away from the transducer in systole. The mosaic indicates turbulent flow with aliasing since the velocity is above the Nyquist limit of the colour Doppler system. Nyquist limit is the maximum velocity which can be imaged by a particular system and is half of the pulse repetition frequency.

Echocardiogram video showing the primum atrial septal defect and the associated tricuspid regurgitation

Patent foramen ovale vs small ASD

Patent foramen ovale or small atrial septal defect?

Echocardiogram from subcostal view showing the interatrial septum with a small defect and left to right flow across. Red colour encodes flow towards the transducer at the top and hence a flow from left atrium (LA) to right atrium (RA). Whether it has to be called a small atrial septal defect (ASD) or a patent foramen ovale (PFO) is the question. Conventionally PFO is a valvular opening which closes when the blood tries to flow from the left atrium to the right atrium. In certain phases of the cardiac cycle or during a Valsalva manoeuvre, right to left flow of blood can occur across the PFO. This is thought to be the mechanism of paradoxical embolism and stroke in case of PFO. Left to right shunt can occur across a stretched open PFO when the right or left atrium enlarges due to another pathological condition which elevates the left atrial pressure. In this case there was an associated ventricular septal defect (VSD). But the size of the defect and the magnitude of the shunt across the VSD was not sufficient enough to produce volume overloading of the left sided chambers.

If there is a spontaneous left to right shunt through out the cardiac cycle, the defect is better considered as a tiny atrial septal defect rather than a PFO. The reason is that PFO by definition, is a valvular opening which permits shunting only right to left. PFO shunts can be detected by contrast echocardiography in which agitated saline is injected into a peripheral vein. If the contrast appears in the left atrium within three cardiac cycles, it is suggestive of right to left shunt across the PFO. Trans esophageal echocardiography may be better for the demonstration of PFO because of higher resolution.

Transcranial Doppler studies will document these bubbles reaching the brain and hence the possibility of paradoxical embolism and stroke in case there is deep vein thrombosis. PFOs have also been associated with migraine like symptoms. Whether these are also related to paradoxical emboli has to be considered.

PFO closure has been recommended for the secondary prevention of stroke as well as for primary prevention of stroke in case of transient ischemic attacks. PFO closure device is similar to the ASD closure device, but differs in two aspects. The right atrial disc is larger, unlike the ASD device. The connecting piece between the two discs is of much lesser diameter compared to an ASD device. The technique of device delivery is similar to that of ASD device closure. Device closure is done under fluroscopy in the cathlab with guidance of device position by trans esophageal echocardiography.

Trans esophageal echocardiogram in atrial septal defect

Trans oesophageal echocardiogram (TEE) is useful in the evaluation of atrial septal defect (ASD) to assess the finer details while deciding on device closure. It is also useful in delineating ASDs which are not visible by trans thoracic echocardiography (TTE) either due to poor echo window or due to odd location of the ASD as in sinus venosus ASD. TEE is often used in this context while evaluating pulmonary hypertension of obscure etiology in an adult. TEE probe being very near the heart without any intervening lung tissue, can give excellent images. Moreover, the short distance permits the use of higher frequency transducers with better image resolution. Usually higher frequency transducers cannot be used for TTE because of poor depth of ultra sound penetration at higher frequencies in an adult.

Atrial septal defect on trans esophageal echocardiography

TEE image in short axis view showing the aorta (Ao), part of the inter atrial septum (IAS) and the ASD. It can be seen that there is hardly any aortic rim (bald aortic rim). Part of the left atrium is seen above the IAS at the top (not marked in the figure). Below the IAS the large right atrium is visible. The TEE probe has a temperature sensor which senses both the subjects temperature as well as the probe temperature. Automatic cooling is initiated when the probe temperature goes above the cut off limit. A visible alert is also displayed when the probe heats up, requesting the operator to reduce the power output of the ultrasound beam. A trade off between visibility of images and the heating up of the probe is required in some cases. Since it is difficult to repeat TEE studies frequently, either continous or frequent recording of TEE videos during the entire study will permit re-assessment by the same operator as well as an independant operator. TEE studies are invariably done in a fasting state and under topical anaesthesia of the oropharynx to reduce gag reflex. A mouth gag is needed to prevent biting and damage to the probe. ECG monitoring is needed to time the events in the cardiac cycle as well for the rhythm in sick individuals. Pulsoximetry and facility for suction are also ideal. Pat. T: temperature of the subject; TEE T: TEE probe temperature. The dial shows the plane of imaging from 0-180 degrees (58 degrees in this image).

Two atrial septal defects with a smal segment of intervening septum

Dual ASDs with a smal intervening segment of atrial septum seen on TEE. The right atrium appears dilated. The total size of both ASDs taken together is quite large and not suitable for device closure.

Measurement of first ASD

First of the two ASDs being measured by calipers. The next image shows the measurements of both ASDs.

Measurements of both ASDs

This image displays the measurements of both ASDs. One measures 17.5 mm and another measures 15.6 mm. The total will be 33.1 mm. The rims at both ends also appear deficient so that device closure may not be feasible in this case. Surgical closure will be ideal, provided that there is no features of irreversible pulmonary hypertension.

Trans esophageal echocardiogram video in atrial septal defect, demonstrating poor aortic rim and dual atrial septal defects in another view.

Device closure of atrial septal defect (ASD)

Device closure of ASD

Device closure of ASD is suitable for secondum ASD with a good rim all around for holding the two discs together. Trans esophageal echo (TEE) is done to assess the superior, aortic and mitral rims as well as the total septal length. It is ideal to have TEE guidance during the procedure as well. A guide wire is introduced through the femoral vein into the inferior vena cava and furthur through the right atrium across the ASD. The tip of the wire is placed in the pulmonary vein and a long venous sheath is introduced. Once the sheath is in position, the device attached to the delivery cable is introduced into the sheath under water to avoid air bubbles in the system. Once the device reaches the left atrium, the left atrial disc of the device is released first and brought in contact with the left atrial side of the ASD. When the position is judged ideal, the right atrial disc is allowed to form by withdrawl of the sheath. Once the two discs are in position with the waist across the ASD, slight wiggling is done to make sure that the device is perfectly fitting and has no tendency for dislodgement. Position is confirmed by TEE with special care to see that the device does not interfere with the function of the AV valves. Once everything is fine, the device is released by unscrewing the delivery cable. The device usually used is the Amplatzer device.

Device closure of ASD in older patients

Generally closure of atrial septal defect (ASD) is done in children and young adults. Benefits of device closure of ASD in older patients are not well documented. A recent study [Khan AA et al. J Am Coll Cardiol Intv, 2010; 3:276-281] involving 23 patients with ASD and aged 50 – 91 years, having ASD size between 16 to 36 mm reported favorable cardiac remodeling and improvement of functional class. The NYHA (New York Heart Association) functional class improved in 16 patients. They had significant improvement in 6 minute walk distance and mental health score. No major complications were noted in these ASD device recipients. They also had significant change in the left ventricular end diastolic and end systolic dimensions at one year after the closure. There was accompanying significant reduction in right ventricular end diastolic dimensions as expected. The improvement of left ventricular function was due to offsetting of the reverse Bernheim effect in which right ventricular dilatation causes a septal bulge and impedance to left ventricular function. Though some studies have shown transient increases in left atrial pressure and consequent pulmonary edema in elderly patients after ASD closure, due to a stiff left ventricle, the current study did not report any such instance. The authors concluded that ASD closure with devices is technically feasible and is associated with favourable cardiac remodeling and improvement in functional class in older patients.

Holt-Oram syndrome

Holt-Oram syndrome was described by Mary Holt and Samuel Oram as ‘ Familial heart disease with skeletal malformations’. Br Heart J. Apr 1960;22:236-42. The initial description was of familial atrial septal defects and abnormalities of the thumb and radial aspect of the upper limb. Simian thumb, in which the thumb lies in the same plane as the other fingers is a characteristic description. Terminal phalanx was curved and pointed inwards. The thumb can also be triphalangeal and finger like, with inability to oppose. Most severe form of upper limb dysplasia resembling phocomelia has also been reported. Atriodigital dysplasia was another name suggested for the Holt-Oram syndrome. The original family described had also cardiac conduction disturbances and arrhythmias.

Holt-Oram syndrome is inherited in an autosomal dominant pattern and the mutation is in the transcription factor TBX5. The mutation was described by Li QY et al in 1997 [Li QY, Newbury-Ecob RA, Terrett JA, Wilson DI, Curtis AR, Yi CH, Gebuhr T, Bullen PJ, Robson SC, Strachan T, Bonnet D, Lyonnet S, Young ID, Raeburn JA, Buckler AJ, Law DJ, Brook JD. Holt-Oram syndrome is caused by mutations in TBX5, a member of the Brachyury (T) gene family. Nat Genet. 1997 Jan;15(1):21-9]. Though the most common cardiac anomaly is atrial septal defect of the secundum variety, other defects like ventricular septal defect have been described.Ventricular septal defect is of the muscular or trabecular variety. Cardiac malformations are seen in 75% of the affected family members. Carpal bone abnormalities are seen in all affected individuals, though it may be clinically silent and evident only radiologically.

Since it is an autosomal dominant mode of transmission, offspring have a 50% chance of being affected. But about 85% of cases of Holt-Oram syndrome have de novo mutations. Mutations in TBX5 account for upto 70% of cases of Holt-Oram syndrome.

Maze I procedure

In the initial maze procedure, position of the sinus node was identified and atriotomies were made surrounding it on three sides to allow impulse propagation in only one direction. Additional incisions were made to direct impulses to all areas of the atrium while interrupting all possible macro reentrant circuits in the atrium. This prevent atrial fibrillation and restored atrioventricular synchrony. The first maze procedure was done on 25th September, 1987.

Maze II procedure

Two important problems with Maze I procedure were chronotropic incompetence of the sinus node and occasional left atrial dysfunction. In Maze II, the incision through the sinus node area in the high lateral right atrium was skipped and the transverse incision at the roof of the left atrium was moved posteriorly to permit better intra atrial conduction. But Maze II had a problem in that it was necessary to transect the superior vena cava to expose the left atrium.

Maze III procedure

In Maze III, placing the septal incision posterior to the opening of the superior vena cava improved the exposure of the left atrium. Higher rates of sinus rhythm was achieved by Maze III procedure and they had improved long term sinus node function. Atrial transport function was better and the need for pacemaker was lesser and so was arrhythmia recurrence. Later it has been performed as a minimally invasive procedure with right sub mammary incision and even without cardiopulmonary bypass.

Maze IV procedure

Even with Maze III, multiple atrial incisions were required contributing to morbidity and complexity of the procedure. In 1990s the first cryomaze procedures were performed, with cryoablation replacing the surgical incisions with transmural ablation lines. The first non-cut-and-sew maze procedure with cryo was performed in 1999. In Maze IV, pulmonary veins are isolated bilaterally and a connecting lesion was also made. Since then various energy sources like radiofrequency, high frequency ultrasound, microwave and laser have been used for creating the ablation lines in Maze procedure [Edgerton ZJ et al. Heart Rhythm. 2009; 6:S1-S4].

The original Ross procedure described in 1965 [Ross DN. Replacement of the aortic and mitral valves with a pulmonary autograft. Lancet. 1967; 2: 956–959] was a subcoronary implant. Full root replacement is the most common operation with the Ross principle being performed now [Sievers HH et al. A Critical Reappraisal of the Ross Operation - Renaissance of the Subcoronary Implantation Technique? Circulation. 2006; 114: I-504-I-511]. Advantages of Ross procedure are the good hemodynamic characteristics, low thrombogenicity and hence doing away with anticoagulants and the potential for growth as the child grows up. But the concerns are the complexity of the procedure (including the need for replacing both aortic and pulmonary valves) and till date the non availability of data on long term performance of the pulmonary valve at the aortic position. The 2006 paper in Circulation cited above gave the mid term results from the same center and the senior author of the paper was Donald N. Ross.

Tetralogy of Fallot – Right aortic arch

Tetralogy of Fallot – Right aortic arch

The lifted up apex (cor en sabot – peasant’s boot shaped heart) due to the right ventricular hypertrophy is seen well in this chest X-ray PA view. The right sided aortic arch is seen intending the tracheal air column on the right side. There is mild cardiomegaly and right atrial enlargement as well in this adult person with tetralogy of Fallot and associated inferior wall myocardial infarction. The lung fields are oligemic due to the right ventricular outflow tract obstruction in Tetralogy of Fallot. Tetralogy of Fallot is the commonest cause of right aortic arch in an adult.

Colour Doppler echocardiography in Tetralogy of Fallot in parasternal long axis view

Tetralogy of Fallot with right to left shunt across the ventricular septal defect

The blue colour is the flow of blood from right ventricle (RV) across the ventricular septal defect into the over-riding aorta. This causes desaturation of aortic blood and cyanosis in Tetralogy of Fallot. The blood from the right ventricle preferentially enters the aorta which is over-riding the ventricular septal defect (VSD) because the right ventricular outflow tract is narrowed in Tetralogy of Fallot as result of infundibular stenosis. The live colour Doppler video below shows the blue flow from RV to aorta across the VSD. Encoding in colour Doppler is blue for flow away from the transducer (located at the top of the sector) and red for flow towards the transducer.

Parasternal long axis view in Tetralogy of Fallot, in diastole

Parasternal long axis (PLAX) view in Tetralogy of Fallot, diastolic frame showing the aortic valve in closed position and mitral valve in open position. The aortic valve appears to impinge on the ventricular septum, but the ventricular septal defect (VSD) with aortic over-ride and connection between right ventricle (RV) and aorta (Ao) is evident just above the septum. LA: left atrium; LV: left ventricle; IVS: interventricular septum; AML: anterior mitral leaflet.

Parasternal long axis view in Tetralogy of Fallot in systole

In the systolic frame the VSD with aortic over-ride is quite evident. The mitral valve is in the closed position. This appearance in parasternal long axis view on echocardiography is not specific for Tetralogy of Fallot. The same appearance in this view can occur in pulmonary atresia with ventricular septal defect as well as in truncus arteriosus. Only other views will help us to differentiate between the three conditions.

Apical five chamber view in Tetralogy of Fallot

Apical five chamber view in Tetralogy of Fallot

Apical five chamber view in Tetralogy of Fallot demonstrating the sub aortic ventricular septal defect (VSD) with aortic over-ride. 50% of the aorta (Ao) is committed to the left ventricle (LV) while the remaining half is committed to the right ventricle (RV). LA: left atrium; RA: right atrium. The VSD in Tetralogy of Fallot is a mal-allignment VSD which results from the mal-allignment of the ventricular septum with respect to the aortico-pulmonary septum during embryonic development. The shift of the aortico pulmonary septum towards the pulmonary side produces both the ventricular septal defect and the narrowing of the right ventricular outflow tract. This theory is sometimes termed the Monology of Fallot meaning that all the four defects in Tetralogy of Fallot (ventricular septal defect, over-riding aorta, right ventricular outflow tract obstruction and hypertrophy of the right ventricle) are in fact due to one defect in the embryonic development.

Apical five chamber view in Tetralogy of Fallot in systole with right to left shunt

Apical five chamber view in Tetralogy of Fallot with colour flow mapping (Colour Doppler imaging) in systole with right to left shunt across the VSD. Blue stream moving from right ventricle across the VSD to the aorta is clearly visualised in this frame. There is also a blue stream from the left ventricle to the aorta.

PDA jet in Tetralogy of Fallot

Patent ductus arerious jet in Tetralogy of Fallot on Colour Doppler imaging

Colour flow imaging shows high velocity jet in the pulmonary artery arising distally, form the descending aorta, suggesting a patent ductus arteriosus (PDA). This is one of the compensatory mechanisms to improve pulmonary flow in Tetralogy of Fallot. Another mechanism is major aorto pulmonary collateral arteries (MAPCA). Intra pulmonary collaterals can also occur in Tetralogy of Fallot. Desc Ao: descending aorta. The image is in the parasternal short axis view.

PDA jet in Tetralogy of Fallot

Continuous wave Doppler interrogation of the jet guided by colour flow mapping picks up the continuous flow with a peak gradient of 61.5 mm Hg. The gradient is calculated from the velocity measured by the device using the formula: V = 4 V². Ao: aorta; PA: pulmonary artery

PDA in TOF Video from Cardiophile MD

The video shows the mosaic jet originating from the distal portion of the pulmonary artery from the descending aorta through the PDA.

Findings to be sought in an aortogram in Tetralogy of Fallot

Aortic regurgitation
Coronary anomalies
MAPCAS (major aortopulmonary collaterals)
PDA (patent ductus arteriosus)
Side of the aortic arch

MAPCA from right internal mammary artery (RIMA)

Still frame from an angiogram with radiocontrast dye injected using a pigtail catheter kept in the right brachiocepalic artery showing major aortopulmonary collateral artery (MAPCA) arising from the right internal mammary artery (RIMA). RSA: right subclavian artery; Right CCA: right common carotid artery; Left CCA: left common carotid artery. Left subclavian artery is not visualised well as the dye reflux into the arch of aorta is not enough to opacify it and the proximal holes of the pigtail are beyond its origin. The second frame (below) gives a better picture of the tortuous branches of the MAPCA. MAPCAs are seen in severe forms of Tetralogy of Fallot and pulmonary atresia. MAPCAs usually arise from the descending aorta.Strictly speaking the collateral arising from RIMA is not a major “aorto” pulmonary collateral, though it can be considered a MAPCA in the wider sense of the meaning. When the lungs are supplied by multiple MAPCAs, they are unifocalised prior to definitive surgical repair of Tetralogy of Fallot. Connecting the distal end of MAPCAs to a single vessel is known as unifocalisation. Collaterals to the pulmoary arterial branches can also arise from the bronchial arteries within the lungs. Hilar collaterals can also occur in pulmonary atresia.

Major aorto pulmonary collateral from RIMA 2

Treatment options and sequelae

Surgical approaches to TOF would include palliative systemic – pulmonary shunts like Blalock-Taussig shunt, Waterston shunt and Potts shunt. Complete repair is accomplisehd by patch VSD closure, resection of subpulmonic obstruction, a transannular patch around the pulmonary valve annulus if necessary and take down of prior shunt. Placement of a transannular patch for widening of the RVOT usually leads to severe pulmonary regurgitation.

Systemic-pulmonary shunt leads to high flow through pulmonary artery, elevated pulmonary vascular resistance and branch pulmonary artery distortion. Survival after repair worse in patients with prior central shunts (Waterston or Potts) possibly due to the higher unrestricted pulmonary blood flow. Some patients with Blalock-Taussig shunts may survive unrepaired into adulthood. These patients should be evaluated for pulmonary artery stenosis and pulmonary hypertension.

Those who had pulmonary valve atresia or anomalous left anterior descending coronary artery may have had prosthetic or homograft conduits with or without a valve placed between the right ventricle and pulmonary artery. Endothelial overgrowth can occur within the conduits and cause obstruction of the right ventricular outflow tract. This can be treated with balloon dilatation or surgical replacement of the conduit.

Echocardiogram after TOF repair

Post TOF repair echo in PLAX view

Echocardiogram after repair of Tetralogy of Fallot (TOF) from the parasternal long axis (PLAX) view showing the hyperechoeic region of the patch which was used to close the ventricular septal defect. The aortic over-ride is no more present. Ao: aorta; RV: right ventricle; LV: left ventricle; LA: left atrium.

Post TOF repair M-mode echo

M-mode echocardiogram after repair of TOF showing the abnormal septal motion which is biphasic and not in line with the movement of the posterior wall which shows regular contractions and relaxations.

Mild PR after TOF repair

The signals above the baseline represent the reverse flow from the pulmonary artery into the right ventricular outflow tract in diastole due to pulmonary regurgitation (PR). The signal is incomplete partly because of the lack of complete allignment of the Doppler beam to the flow and partly because the regurgitation is only mild. In most cases of repaired TOF, there will be significant PR. In some cases it may be even severe enough to produce late right ventricular dysfunction. Here it is not that severe.

Pumonary valve M-mode echocardiogram after TOF repair

M-mode echocardiogram of the pulmonary valve after TOF repair, showing almost normal pattern with an A wave just before the onset of systole. The diastolic portion of the movement is better seen than the systolic portion. The pulmonary valve echocardiogram shows a prominent (deep) A wave in pulmonary stenosis and a flat A wave in pulmonary hypertension.

Apical five chamber view after TOF repair

Apical five chamber (5C) view after TOF repair, showing the patch in the subaortic region where the VSD (ventricular septal defect) was closed. ATL: anterior tricuspid leaflet.

Post TOF repair TR

Tricuspid regurgitation jet (TR) seen after TOF repair, with a gradient of 32 mm Hg, indicating mildly elevated right ventricular pressures. The right ventricular pressure prior to repair would have been equal to systemic pressure. TR jet is depicted below the baseline because the flow is away from the transducer kept at the apex.

Subcostal view showing intact atrial septum

Colour Doppler echocardiographic video after repair of Tetralogy of Fallot. The patch closing the ventricular septal defect is seen as a hyperechoeic region below the aortic valve, both in the parasternal long axis view and the apical five chamber view. Colour flow mapping shows that there is no residual VSD flow across the septum in that region. Short axis imaging shows mild PR and apical four chamber imaging shows mild TR. Subcostal view demonstrates the intact inter atrial septum.

Mechanisms of aortic regurgitation in operated tetralogy of Fallot

Pulmonary regurgitation is almost universal after corrective repair of tetralogy of Fallot, more so in those who require a trans annular patch for widening of the right ventricular outflow tract. Hence an early diastolic murmur along the left sternal edge following repair of tetralogy of Fallot is most often due to pulmonary regurgitation. But a few cases may also develop aortic regurgitation due to various reasons. Aorta is dilated in tetralogy of Fallot prior to repair because it receives a major portion of the out put from the right ventricle as well as the left ventricular output. This is the reason for a high volume pulse in tetralogy of Fallot. Thus dilatation of the aortic root is one of the potential reasons for aortic regurgitation in tetralogy of Fallot. Other causes are lack of support due to a sub aortic ventricular septal defect and valvular deformation resulting from retraction of the surgical patch.

Potential for sudden cardiac death after surgical repair of tetralogy of Fallot

The risk of sudden cardiac death in operated tetralogy of Fallot is 25-100 fold than in the general population and it can occur decades after correction. The risk is related to QRS duration more than 180 milliseconds. The QRS widening is related to pulomonary regurgitation, right ventricular dilatation and conduction defect. Atrial arrhythmias also common after TOF repair. Hemodynamic effects of pulmonary regurgitation include chronic right ventricular volume overload, right ventricular dysfunction and exercise intolerance. Pulmonary valve replacement can decrease QRS duration and stabilise right ventricular function, though the timing is unclear; but earlier would be better than later. Right ventricular function can be evaluated by echo or magnetic resonance imaging (MRI).

It is well known that adults with previously operated tetralogy of Fallot can develop ventricular tachyarrhythmias and die suddenly. They are prone for ventricular tachycardia as well as atrial tachyarrhythmias like atrial flutter and fibrillation. Syncope may be a fore runner of sudden death in some individuals with operated tetralogy of Fallot and calls for evaluation. An annual incidence of 0.4 percent sudden death during the first twenty five years after surgery has been reported. Both the surgical scar as well as the dilatation of right ventricle and right atrium due to the pulmonary and tricuspid regurgitation are thought to have roles in arrhythmogenesis. Highest risk is in those with marked cardiomegaly (cardiothoracic ratio more than 60 percent), severe pulmonary and or tricuspid regurgitation, QRS duration on the electrocardiogram of more than 180 milliseconds, and a QT interval dispersion of more than 60 milliseconds.

[Gatzoulis MA, Till JA, Somerville J, Redington AN. Mechanoelectrical interaction in tetralogy of Fallot: QRS prolongation relates to right ventricular size and predicts malignant ventricular arrhythmias and sudden death. Circulation 1995;92:231-7.

Gatzoulis MA, Till JA, Redington AN. Depolarization-repolarization inhomogeneity after repair of tetralogy of Fallot: the substrate for malignant ventricular tachycardia? Circulation 1997;95:401-4]

Surgical correction of pulmonary regurgitation with a valvular prosthesis and tricuspid regurgitation by annuloplasty may decrease the chance of atrial and ventricular arrhythmias. This is more likely if surgical repair is also accompanied by mapping and ablation of the reentry circuit of arrhythmia [Therrien J, Siu SC, Harris L, Dore A, Niwa K, Janousek J, et al. Impact of pulmonary valve. replacement on arrhythmia propensity late after repair of tetralogy of Fallot. Circulation 2001;103: 2489-94]