Early repair of type A aortic dissection complicated by coma has bee reported to improve neurological outcome [Tsukube T et al. Neurological Outcomes After Immediate Aortic Repair for Acute Type A Aortic Dissection Complicated by Coma. Circulation. 2011; 124: S163-S167]. Repair initiated within five hours of onset of symptoms is found to be superior than a delayed repair in this study. Hospital mortality was fourteen percent in the immediate group while it was sixty seven percent in the delayed group. Neurological recovery was also better with a National Institutes of Health Stroke Scale score of 31.4±6.6 in the immediate group while it was 28.3±9.5 in the delayed group. The score further improved to 6.4±8.4 and the cumulative survival rate was 71.8% in 3 years with independence in daily activities achieved in 52% (eleven out of twenty one). The authors conclude that immediate repair of dissection is warranted in those with type A aortic dissection and coma for better survival and neurological recovery.
Surgical ablation superior but riskier than catheter ablation for atrial fibrillation
Boersma LVA and associates [Atrial Fibrillation Catheter Ablation Versus Surgical Ablation Treatment (FAST) / Clinical Perspective : A 2-Center Randomized Clinical Trial. Circulation. 2012;125:23-30] randomized drug refractory atrial fibrillation with left atrial enlargement and hypertension as well as those with failed prior attempts at cathter ablation to either surgical ablation or catheter ablation. Two thirds of the cases had failed catheter ablation earlier. The catheter ablation for the study included linear antral pulmonary vein isolation and additional ablation lines if needed. Surgical isolation included bipolar radiofrequency isolation of pulmonary veins on both sides, ablation of ganglionated plexi and excision of left atrial appendage with optional additional lines. Freedom from atrial arrhythmia was more with surgical ablation of 65.5% vs 36.5% with catheter ablation, at tweleve months follow up. Procedural complications were more in the surgical group (34.4 percent vs 15.9 percent).
Factors contributing to variability in response to clopidogrel or clopidogrel resistance
Genetic factors responsible for variability in clinical response to clopidogrel include polymorphisms of CYP (Cytochrome P), GPIa (Glycoprotein Ia), P2Y12 and GPIIIa (Glycoprotein IIIa). Clinical factors which contribute to a variable response to clopidogrel may be poor compliance, lower doses, poor absorption, drug-drug interactions involving CYP3A4, acute coronary syndrome, diabetes mellitus/insulin resistance and elevated body mass index. Cellular factors which may cause clopidogrel resistance may be accelerated platelet turnover, reduced CYP3A metabolic activity, increased ADP exposure, upregulation of the P2Y12 pathway, upregulation of the P2Y1 pathway and upregulation of P2Y–independent pathways (collagen, epinephrine, TX2 or thromboxane A2, thrombin) [Angiolillo DJ et al. Variability in individual responsiveness to clopidogrel: clinical implications, management, and future perspectives. J Am Coll Cardiol. 2007;49):1505-16].
Intra thoracic impedance monitoring with audible alert in heart failure management
Intra thoracic impedance monitoring with audible alert has been tried in heart failure management. This technology incorporated in heart failure devices [(cardiac resynchronization therapy (CRT)] and implantable cardioverter-defibrillator (ICD) is used to assess the volume status and advice early hospitalization if needed. van Veldhuisen DJ and associates from the Department of Cardiology, University Medical Center Groningen, University of Groningen, Netherlands studied 335 patients with chronic heart failure who had undergone implantation of CRT or ICD [Intrathoracic Impedance Monitoring, Audible Patient Alerts, and Outcome in Patients With Heart Failure. Circulation. 2011; 124: 1719-1726]. According to the authors, though the device increased heart failure hospitalizations and out patient visits in heart failure patients, it did not improve the final outcome in terms of mortality or heart failure hospitalizations.
Cox maze procedure I, II, III and IV for atrial fibrillation
Surgical procedures for atrial fibrillation are called Cox maze procedure in recognition of the pioneering work done by Cox and his colleagues [Cox JL et al. The development of the Maze procedure for the treatment of atrial fibrillation. Semin Thorac Cardiovasc Surg. 2000; 12: 2–14]. Initial work on atrial fibrillation from this group was left atrial isolation. Though this produced sinus rhythm in right atrium left atrium continued to fibrillate and was a source for thromboembolism.
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].
Ventricular septal defect (VSD)
Swiss cheese ventricular septal defects
Multiple muscular ventricular septal defects (VSD) are also called ‘swiss cheese’ VSD. Swiss cheese VSDs are difficult to close surgically. It is difficult to locate the openings of the VSD from the right ventricular side. Some may have multiple right ventricular openings for a single left ventricular orifice. When one right ventricular orifice is closed, the VSD may be seen puffing from another orifice. These VSDs require left ventriculotomy for closure which is a problem in a small infant. Due to the difficulty fo surgical closure, often a pulmonary artery banding is all that is done in these cases, to control the excessive pulmonary blood flow and development of pulmonary arterial hypertension. Swiss cheese VSDs are associated with left axis deviation on ECG.
Katz-Wachtel phenomenon / sign on ECG in ventricular septal defect
Katz-Wachtel sign / phenomenon
Click on the image for an enlarged view
The Katz-Wachtel sign is tall diphasic RS complexes at least 50 mm in height in lead V2, V3 or V4 – mid precordial leads [Circulation 1963;27;1118-1127 (Free full text at: http://circ.ahajournals.org/cgi/reprint/27/6/1118.pdf); original description by Katz and Wachtel was published in 1937: Katz LN and Wachtel H. The diphasic QRS type of electrocardiogram in congenital heart disease. Am Heart J; 1937, 13: 202-206]. The sign has been described in ventricular septal defect with biventricular hypertrophy in children. It can be seen with isolated ventricular septal defect as well as complex ventricular septal defect. In fact the Circulation article cited is on Complete Transposition of the Great Vessels: II. An Electrocardiographic Analysis by Larry P et al.
Ventricular septal defect – perimembranous
Perimembraneous ventricular septal defect (VSD)
Medium sized ventricular septal defect in peri-membranous location seen from the apical five chamber view. RV: right ventricle; LV: left ventricle; VSD: ventricular septal defect; Ao: aorta; RA: right atrium; LA: left atrium; IVS: interventricular septum. There is aneurysm of the inteverventricular septum covering the VSD, leaving a small gap. The VSD jet passes through this small defect which is restrictive (below).
VSD Jet on continuous wave Doppler
VSD jet documented by continuous wave Doppler interrogation, showing an interventricular gradient of 61.5 mm Hg, which suggests that the defect is restrictive. Actual gradient may be even more as this jet has an incomplete envelope.
Echocardiographic profile in ventricular septal defect
Ventricular septal defect (subaortic) seen from parasternal long axis view
Parasternal long axis view showing aorta (Ao), left atrium (LA), left ventricle (LV) and a small perimembranous (subaortic) ventricular septal defect. Mitral valve is in the open position and the aortic valve in the closed position.
VSD Jet visualised by colour flow mapping (colour Doppler)
Colour sector in parasternal long axis view shows the mosaic (multi-coloured) VSD jet across the perimembranous VSD from the left ventricle to the right ventricle. It is a high velocity jet because the VSD is restrictive. The neck of the jet almost corresponds to the size of the VSD. VSD jet is seen in a systolic frame.
Continuous wave Doppler interrogation of VSD jet
VSD jet can be picked up in parasternal long axis or short axis view, guided by color Doppler. It may also be picked up from the apical four chamber view, but the allignment may not be good. Pulsed Doppler cannot measure the jet velocity as it is much higher than the Nyquist limit of the pulsed Doppler system. Hence continuous wave Doppler is used for interrogation of the VSD jet. The interventricular gradient is calculated using the Bernoulli equation. A high interventricular gradient indicates that the VSD is restrictive. A low gradient indicates unrestrictive VSD and pulmonary hypertension.
Colour Doppler echocardiogram video in perimembranous ventricular septal defect.
Ventricular septal defect and aortic regurgitation
Aortic regurgitation is more likely to occur in subpulmonic ventricular septal defect (VSD) than perimembranous VSD. Aortic cuspal prolapse occurs in 4 – 9% of VSDs and aortic regurgitation in 2 – 6% of VSDs. But the prevalene of aortic cusp prolapse in subpulmonic VSDs is upto 73% and the occurrence of aortic regurgitation about 52 to 78%. While 62% of those with aortic cusp prolapse along with subaoric VSD have aortic regurgitation, 77% to 90% of those with subaoric VSD and aortic regurgitation have aortic cusp prolapse. A study by Saleeb SF et al (Am J Cardiol. 2007;99:1588-92) evaluated 100 patients with subaortic VSD diagnosed in the first year of life, but did not need surgery in infancy were evaluated for the development of aortic regurgitation on follow up. The follow up period ranged from one to twenty four years with a mean of about seven years. Initial VSD size was small in 38 patients, moderate in 50 patients and large in 12 patients. Spontaneous closure of VSD occurred during the follow up period in 4 patients with at a mean age of 6 years with a range of 3.4 to 12.7 years. Three of them had small VSDs and one of them had a moderate sized VSD. Aortic cusp prolapse developed in 14 patients at a mean age of 7.1 years with a range of 0.4 to 18.4 years. The murmur of aortic regurgitation was audible in six patients at mean age of 5.1 ± 3.1 years. All of them had aortic cusp prolapse and underwent surgery with VSD closure and aortic valvuloplasty.
LV – RA shunt: echocardiographic video
A shunt from the left ventricle to the right atrium can occur in three ways: (1) Defect in the atrioventricular septum between the septal attachments of the mitral and tricuspid valves (2) A perimembraneous ventricular septal defect (VSD) with associated fenestration of the septal tricuspid leaflet so that the VSD jet is partly directed from the left ventricle across the interventricular septum through the tricuspid valve into the right atrium (3) Ventricular septal defect with tricuspid regurgitation so that the blood shunted from the left ventricle is passed immediately to the right atrium to produce a step up in oximetry.
A defect in the atrioventricular septum was described by Gerbode F et al in 5 operated cases in 1958 [Gerbode F., Hultgren H., Melrose D., Osborn J. Syndrome of left ventricular-right atrial shunt: successful surgical repair of defect in five cases, with observation of bradycardia on closure. Ann Surg 1958;148(3):433-446]. Anatomically this defect is possible because the septal attachment of the tricuspid valve is distal to that of the mitral valve so that there is a small region of the septum which is between the left ventricle and the right atrium, known as the atrioventricular septum. Usually the defect is congenital. But cases are on record in which the septal defect was acquired due to infective endocarditis. It is mentioned that congenital variety of defect occurs inferior to the tricuspid valve while the aquired variety is superior to the valve.
LV – RA shunt in perimembranous VSD across STL fenestration
The still image shows both the jet from the left ventricle to the right ventricle across the perimembranous VSD and the jet from left ventricle to right atrium across the VSD, through the fenestration in the septal tricuspid leaflet into the right atrium.
Echocardiographic video (color Doppler) showing LV – RA shunt through VSD, across the STL
Initial view shows the mosaic jet from left ventricle to right ventricle across the subaortic VSD as well as another jet traversing the defect in the septal tricuspid leaflet into the right atrium. This second jet resembles a tricuspid regurgitation jet. Second view is the parasternal short axis view of flow from the left ventricule to right ventricle, in the classical location of a perimembranous VSD.
During echocardiographic evaluation, the jet of the Gerbode VSD is likely to be mistaken as a tricuspid regurgitation jet. This will cause misinterpretation as severe pulmonary hypertension while in fact the right ventricular pressures may be low. This can be identified by carefully visualizing the jet origin on colour Doppler. The structural defect can also be seen by careful two dimensional imaging. Pulmonary arterial pressure can be counter checked by using the pulmonary regurgitation jet.
Hepatoclavicular view for left ventriculography
LAO (left anterior oblique) 40 degrees with 40 degrees cranial angulation is known as hepatoclavicular view. It is used to profile inlet ventricular septal defects. Sub pulmonic VSDs may be seen only in RAO (right anterior oblique) views.
Long term (more than a decade) follow up of Ross procedure
Ross procedure or living pulmonary auto graft is an alternative for young an middle aged individuals requiring aortic valve replacement in view of the faster degeneration of bioprostheses in this age group and the thromboembolic and bleeding risks with mechanical prosthesis. Charitos EI et al from Luebeck in Germany report a large series [Long-Term Results of 203 Young and Middle-Aged Patients With More Than 10 Years of Follow-Up After the Original Subcoronary Ross Operation. Ann Thorac Surg. 2011 Dec 22. (Epub ahead of print)] of over two hundred cases with more than a decade of follow up, from among nearly six hundred Ross procedures performed in their center between 1994 and 2011. The data is exclusively on the original subcoronary Ross operation and the follow is of about two thousand and five hundred patient years. Ninety two percent had freedom from re-operation at ten years and eighty seven had freedom from re-operation at fifteen years. Early mortality was less than one percent and late mortality was about eleven percent. No significant increase in aortic regurgitation or root dimension was noted on follow up.
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.
Importance of average blood pressure measured by 24 hour BP monitoring
Devices for monitoring ambulatory blood pressure are becoming more popular, with more and more hospital acquiring these devices. It can monitor blood pressure at varying preset intervals as specified in the device program. Average daily blood pressure can also be derived from the computer analysis of the recordings. White WB and associates investigated the role of average blood pressure on the progression of cerebrovascular disease and cognitive decline in the elderly [Average Daily Blood Pressure, Not Office Blood Pressure, Is Associated With Progression of Cerebrovascular Disease and Cognitive Decline in Older People. Circulation. 2011; 124: 2312-2319]. They evaluated ambulatory and clinic measured blood pressure, gait studies, magnetic resonance imaging of the brain and neuropsychological tests performed at baseline and at two years follow up. They documented that ambulatory blood pressure correlated with increased white matter hyperintensity volume on T2 weighted imaging, but not the clinic measured blood pressure. Similar correlation was noted with measures of executive function and processing speed of the brain.
Double internal mammary grafts superior to LIMA plus radial artery grafts
Arterial grafts used for coronary revascularisation is better than venous grafts. But radial artery is a free graft while internal mammary artery is taken as a live graft with its proximal end arising from the subclavian artery. Ruttmann E and colleagues [Second Internal Thoracic Artery Versus Radial Artery in Coronary Artery Bypass Grafting. A Long-Term, Propensity Score–Matched Follow-Up Study. Circulation. 2011; 124: 1321-1329] compared the use of a second internal mammary artery versus radial artery for coronary artery bypass grafting. Perioperative adverse cardiac and cerebrovascular events were significantly lower in the dual internal mammary artery grafting group compared one internal mammary artery plus radial artery group (1.4% versus 7.6%, P<0.001). The fact that internal mammary arteries are less susceptible to atherosclerosis is the main reason for extra benefit with dual internal mammary artery grafts. Radial artery has a lower capacity to release nitric oxide, which seems to have a role in the susceptibility of the radial artery to atherosclerosis [He GW and Liu ZG. Comparison of nitric oxide release and endothelium-derived hyperpolarizing factor–mediated hyperpolarization between human radial and internal mammary arteries. Circulation. 2001;104(suppl):I-344–I-349]. Right internal mammary artery can be used as an in situ graft by routing it through the transverse sinus of the pericardium. Though there was higher risk of deep sternal infections in previous studies of dual internal mammmary grafts, the incidence of sternal dehiscence was not higher in the current study, probably because of the use of skeletonized mammary artery grafts rather than the conventional pedicled grafts. Skeletonized mammary artery grafts are known to have lower incidence of sternal ischemia.
Tetralogy of Fallot (TOF)
The four cardinal features of tetralogy of Fallot (TOF) are malalignment ventricular septal defect (VSD) with an overriding aorta, infundibular pulmonary stenosis and right ventricular hypertrophy. The variability in clinical presentation of TOF correlates with degree of right ventricular outflow tract (RVOT) obstruction and the size/anatomy of pulmonary artery an its branches.
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)
- MAPCA from right internal mammary artery 1
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]