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CONGENITAL HEART DISEASE WITH LEFT TO RIGHT SHUNT Michael Pieters Dept. of Diagnostic Radiology Bloemfontein OVERVIEW Classification of congenital heart lesions Factors that influence lesion presentation Imaging chain sequence Left to right Shunt lesions Anatomy Physiology Imaging CLASSIFICATION OF CONGENITAL CARDIAC LESIONS Shunt lesions Right heart lesions Left heart lesions Abnormal origin of the great arteries FACTORS THAT INFLUENCE LESION PRESENTATION Age of child Severity of the lesion Example – VSD R to L shunt at birth L to R shunt with CCF as age increases The anatomy of the lesion remains constant Radiographic features and clinical findings change with time Classic radiographic features of certain lesions – rarely seen IMAGING CHAIN SEQUENCE The imaging sequence varies with Age Clinical presentation Type of lesion Echocardiography Chest Radiography CT MRI Angiography CONGENITAL CARDIAC LEFT TO RIGHT SHUNT LESIONS ASD VSD PDA Ductus Arteriosus Aneurysm Aortico-Pulmonary Window CARDIOMEGALY Cardiomegaly on CXR Asses pulmonary vascularity - ? Increased Read history - ? Acyanotic patient Ddx: ASD AVSD VSD PDA Aortico-pulmonary window ASD 10% of all CHD Incidence - twice as common in females Secundum defects – likely genetic cause Holt Oram Familial ASD ASD ANATOMY 3 Primary types Relationship to the fossa ovalis Secundum defects (80%) Region of fossa ovalis Ostium Primum defects (10%) Caudal to the fossa ovalis Sinus Venosus defects (10%) Posterior to the fossa ovalis ASD – SINUS VENOSUS DEFECTS Not true ASD’s Defect in the septum which separates the sinus venosus portion of the RA from the right pulmonary veins and systemic veins Most often found in the wall between the Posterior inferior border of SVC and RA Commonly assosciated with anomalous connection of Right upper, middle or lower pulmonary veins draining to the RA or SVC ASD – SINUS VENOSUS DEFECTS Much less commonly - defect is found in the wall between the Inferior RA at its junction with the IVC Assosciated with anomalous connection of Right middle or lower pulmonary veins draining to the RA or SVC ASD – CORONARY SINUS SEPTAL DEFECTS Rare spectrum of lesions Partial or complete absence of wall between Coronary sinus and LA Associated with a left SVC draining to the coronary sinus Blood shunts from the LA to the RA via “unroofed” coronary sinus ASD – PATENT FORAMEN OVALE Foramen Ovale Located between septum secundum and primum Normally patent prenatally Allows O2 rich blood from ductus venosus -> reach LA Sealed after birth Increased LA pressure vs RA Probe patency 25% of adults Functionally closed Right to left shunt possible - Valsalva ASD – COMMON ATRIUM Atrial septum completely absent Common in visceral heterotaxy syndromes ASD - PHYSIOLOGY Left to right shunt volume determined by ASD size Left heart compliance Pulmonary vascular resistance Large defects show increased size of RA RV Pulmonary artery Right to left shunt will occur when Pulmonary vascular resistance > Systemic vascular resistance ASD – CLINICAL PRESENTATON Detected 1-2 yr of age May present earlier @ 6 -8 weeks with murmur Older children with large ASD Fatigue and dyspnoea Split second heart sound – no variation with respiration Diastolic flow murmur Adults – flow related pulmonary arterial hypertension ASD IMAGING - ECHOCARDIOGRAPHY Modality of choice for Dx Localising Size Shunt direction and severity (Colour Doppler) Right ventricular qualitative function Septal bowing (Rt to Lt) Points to volume overload ASD IMAGING - ECHOCARDIOGRAPHY Right ventricular pressure Assessed by evaluating the degree of: Tricuspid regurgitation Septal systolic position (systolic septal flattening – increased RV pressure) PFO Dx – flap valve or Saline injection to right heart + Valsalva Rt to Lt shunt on Valsalva TEE ASD IMAGING – CHEST RADIOGRAPHY Neonate Normal cardiac size Normal pulmonary flow Later infancy and childhood Mild cardiomegaly Triangular cardiac silhouette Left atrium normal distinguishes uncomplicated ASD from other L ->R lesions) Main pulmonary artery enlarged Eisenmenger syndrome findings Seen in pulmonary hypertension Large central pulmonary arteries Peripheral pulmonary artery tapering ASD IMAGING – CHEST RADIOGRAPHY Mild to moderate cardiomegaly Increased pulmonary vascularity No left atrial dilatation ASD – IMAGING Angiography Asses haemodynamic consequences of ASD or Used if transcatheter closure is planned MRI Adjunct to echo >90% sensitive and specific for ASD localization and detection Useful in pt with poor acoustic windows Can lead to ASD being misdiagnosed atrial septum is thin on BW images – rather use MRI cine GE and steady state free precession cine – shows turbulent jet over ASD Cine phase contrast sequences Show direction and amount of shunting ASD – MRI DYNAMIC PERFUSION STUDY PFO can be demonstated by injecting Gadolinium into the right heart + Valsalva ASD haemodynamic evaluation Demonstrates Eisenmenger syndrome physiology Contrast seen crossing the atrial septum from the RA to the LA AVSD 2-5% of all CHD 40% of Down’s syndrome patients have CHD 40% of Down’s pt with CHD have AVSD Associated with visceral heterotaxia / asplenia and polysplenia syndromes Ellis van Creveld syndrome AVSD Lesions associated with AVSD PDA (10%) Tetralogy of Fallot (6%) Transposition of the great arteries Double outlet RV Aortic coarctation AVSD - ANATOMY Abnormal development of the endocardial cushions Mild form - partial AVSD: Crescent shaped defect in the inferior portion of the atrial septum adjacent to the AV – valves Cleft mitral valve Separate mitral and tricuspid valve orifices AVSD - ANATOMY Complete form: Single AV-valve Ostium primum ASD just superior to the plane of the AV – valve Large VSD beneath the plane of the AV - valve Cleft in the anterior leaflet of the mitral valve Cleft in septal leaflet of tricuspid valve The common AV-valve has 5 leaflets Shortened left ventricle inlet Left ventricle papillary muscle defects abnormally close to each other or only one papillary muscle Unbalanced AVSD Relative hypoplasia of one of the ventricles AVSD - PHYSIOLOGY Complete AVSD Left to right shunt - related to size of defect and pulmonary vascular resistance Shunting may be interatrial or interventricular Cleft Mitral Valve leads to mitral regurgitation and CCF Pulmonary hypertension develops (more common in Down’s pts) AVSD PRESENTATION Infants with complete AVSD Tachypnoea, tachycardia CCF sx when pulmonary resistance starts to fall Signs and symptoms vary according to the degree of shunting Partial AVSD Infants usually asymptomatic Can present earlier if severe mitral incompetence AVSD - IMAGING Echocardiography Accurately demonstrates AVSD components Ostium primum defect Inlet portion of the ventricle Abnormal valve leaflet morphology Papillary muscle architechture Shunt level and flow direction Ventricular function and size Evaluate for outflow tract obstruction Pulmonary and systemic venous anatomy (must be documented because of frequency of associated heterotaxy abnormalities) AVSD - IMAGING Chest Radiography Moderate to marked cardiomegaly RV and RA enlargement (more in complete AVSD) Increased pulmonary vascularity Left atrial enlargement – if associated mitral incompetence Lung infiltrates (increased pulmonary blood flow associated with recurrent LRTI) Lung hyperinflation – seen with large left to right shunts due to increased blood volume with increased overall lung volume as well as increased airway resistance from enlarged arteries and veins AVSD - IMAGING Chest Radiography Cardiomegaly Pulmonary plethora AVSD - IMAGING Cross sectional imaging Not needed in initial Dx Used to confirm Dx and evaluate the size and morphology of the atria, leaflets, ventricles and great vessels Evaluate ventricular function Cine phase contrast MRI Assessment of shunt fraction (Qp/Qs) Valvular function AVSD - IMAGING Angiocardiography Rarely necessary for Dx Used if Dx is unclear or haemodynamic information is needed Long axis ventriculogram Goose neck deformity of left ventricular outflow tract Anterior superiorly positioned aortic valve Elongated and narrowed LV outflow tract VSD 20% of all CHD 2/1000 Live briths VSD + complex CHD account for > 50% of CHD Most common lesion in trisomy 13,18 and 21 Incidence slightly higher in females Incidence varies on age of evaluation Most small VSDs close spontaneously VSD Isolated or as part of complex CHD Tetralogy of Fallot Truncus arteriosus ASD Coarctation of the aorta Tricuspid atresia Transposition of the great arteries Double outlet RV VSD - ANATOMY 4 Components of the ventricular septum Inlet septum Muscular septum Outlet septum Membranous septum VSD involves one or more component VSD - ANATOMY Inlet septum Contains AV valves and their attachments Formed from endocardial cushions AVSD defect location Muscular septum Trabeculated portion of RV (viewed from RV) From tricuspid valve leaflets to RV apex and crista supraventricularis Location of single or multiple muscular defects Outlet septum Extends from the crista supraventricularis to pulmonary valve (viewed from RV) Membranous septum Inferior to the right and non-coronary cusps of the aortic valve 80% of VSDs involve this area VSD - PHYSIOLOGY Physiologic ef fect determined by VSD size Rt and Lt heart compiance Pulmonary vascular resistance Small defects High flow resistance Large defects Low flow resistance High blood flow in the pulmonary vasculature Leads to pulmonary vascular obstructive disease VSD - SYMPTOMS Symptoms dictated by VSD size Degree of Left to Right shunt Typical signs in > 1 month of age PSM as pulmonary resistance falls No murmur in large VSD Loud split 2 nd heart sound Significant shunt Failure to thrive Dyspnoea CCF Irreversable pulmonary vascular obstructive disease Shunt reversal VSD - IMAGING Echocardiography Method of choice Used to asses the location, number and size of VSDs Shunt assessment Colour Doppler is useful to identify muscular VSDs RV + Pulmonary artery pressures measured Rt + Lt heart volumes are measured Tricuspid and Aortic valves Assessed for possible tethering of the valve tissue into the defect borders TEE used if poor acoustic windows VSD - IMAGING Chest Radiography Findings depend on VSD size Small VSD – may have normal CXR Moderate to large VSD Cardiomegaly with LA, LV, RV enlargement Enlarged pulmonary arteries Increased pulmonary blood flow CCF frequent in infants + large defects Older children – pulmonary hypertension likely Large central pulmonary arteries Pruned peripheral pulmonary arterial branches VSD – CROSS SECTIONAL IMAGING Echocardiography usually suf ficient Muscular VSDs sometimes detected on routine CT Chest MRI 90% accuracy in VSD detection Larger defects seen with Spin Echo or Double inversion recovery techniques Smaller defects seen with GE or Steady state free precession images VSD – CROSS SECTIONAL IMAGING MRI Shunt evaluation Cine phase contrast measurements in aorta and pulmonary artery Rt + Lt Ventricular stroke volume comparison Quantative assessment Rt and Lt ventricular function Rt and Lt ventricular volumes Ejection fractions Evaluation for extracardiac vascular anomalies VSD - IMAGING Angiocardiography Used to Assess pulmonary vascular resistance Quantify intracardiac shunting Evaluate for ventricular septal defect anatomy Evaluate the coronary arteries Evaluate for associated valvular and vascular anomalies Angiocardiography used if echocardiographic evaluation was insuf ficient or if transcatheter VSD closure is planned PDA 5-10% of CHD 1/1600 live births Twice as common in females 20-30% of prems have PDA Often associated with VSD Aortic coarctation Aortic stenosis Mitral regurgitation PDA - ANATOMY Persistence of embryologic 6 th aortic arch 6 th Aortic arch connects Lt pulmonary artery with descending aorta PDA may be on the right with a Rt arch PDA - ANATOMY Ductus Arteriosus / Aorta angle Acute angle seen in isolated PDA with pulmonary atresia Ductal dependant pulmonary flow Obtuse angle seen in Non-ductal dependant pulmonary flow PDA –PROSTAGLANDINS AND O2 PG keep the duct patent during foetal life At birth blood [O2] rises and [PG] lowers Functional ductal constriction Complete closure @ 2 months Ligamentum arteriosum remains (may calcify) In Premature infants closure is delayed due to Less sensitive ductal tissue to [O2] Respiratory distress – hypoxia -> increased [PG] In full term infants Rubella Asphyxia Genetic and environmental causes PDA - PHYSIOLOGY Amount of Lt to Rt shunt dictated by Ductal length and diameter Degree of pulmonary hypertension Untreated PDA leads to Pulmonary vascular obstructive disease Prem with no significant lung disease Systolic high frequency murmur CCF (large shunt) Prem with significant lung disease PDA prevalence > 80% Almost inaudable murmer Dx with echocardiography PDA - PHYSIOLOGY Term infant with small PDA Usually asymptomatic Murmur present Infant with moderate to large PDA Continuous machinary like murmur FTT Poor feeding CCF Irritability PDA IMAGING Echocardiography Standard imaging technique PDA size and diameter L->R Shunt fraction Degree of pulmonary hypertension Can identify complicating factors – ductal aneurysm or calcification Chest Radiography Premature infants Pulmonary oedema Cardiomegaly +- Associated lung disease PDA IMAGING Chest Radiography Term infants CXR may be normal Term infants with significant shunting Cardiomegaly Increased pulmonary blood flow Consider PDA in a prem infant with Increasing granularity of lung fields Increasing heart size on serial imaging PDA - IMAGING Chest Radiography Prominent ascending aorta and arch Helps differentiate ASD and VSD from PDA ASD and VSD have a normal aortic arch Ductus bump Prominence of the descending aorta PDA - IMAGING Cross sectional Imaging Reserved for complicated cases to define anatomy CT / MRI – ductal size and length Cine phase contrast sequences Can quantify the amount of flow through the PDA PDA - IMAGING Angiocardiography Reserved for cases where significant pulmonary hypertension is suspected Assess Pulmonary vascular resistance Ductal morphology if transcath closure planned ANEURYSM OF THE DUCTUS ARTERIOSUS (DAA) 1 .5 – 8.8% of full term infants Usually Dx pre-natally or after birth in asymptomatic patients Possible association with connective tissue disorders Ehlers-Danlos syndrome DAA - ANATOMY Saccular or fusiform dilation of the PDA Etiology unknown ? Intrinsic weakness of wall of the duct ? Delayed closure of aortic side of duct with exposure to systemic pressures DAA - IMAGING Chest Radiography Ductal bump in area of main pulmonary artery and aortic arch Echocardiography Most oft modality used for Dx MRI/CT or Angiography Rarely used to confirm the Dx AORTICO-PULMONARY WINDOW Rare – 0.2% CHD 30-50% associated with other abnormalities VSD ASD PDA Tetralogy of Fallot Interrupted aortic arch Aortic coarctation Subaortic stenosis Anomalous coronary arteries – pulmonary trunk origin AORTICO-PULMONARY WINDOW ANATOMY Incomplete division of the primitive common arterial trunk Two distinct semilunar valves Large oval communication between ascending aorta and pulmonary trunk above the aortic valve AORTICO-PULMONARY WINDOW –MORI CLASSIFICATION Mori type I Involves the proximal medial wall of the ascending aorta Mori type II Involves the distal posterior wall of the ascending aorta Mori type III Involves the medial and posterior walls of the ascending aorta AORTICO-PULMONARY WINDOW PHYSIOLOGY Large high pressure Lt to Rt shunt Presents in 1 st weeks of life CCF commonly seen Systolic ejection murmur may be heard Diastolic murmur – associated pulmonary insuf ficiency Bounding pulses frequently encountered AORTICO-PULMONARY WINDOW IMAGING Echocardiography Method of choice For evaluation of defect anatomy Relationship to the aortic and pulmonary valves To define coronary anatomy Pulmonary pressure and ventricular function Other defects Chest Radiography Mimics PDA on CXR Cardiomegaly LA + LV enlargement Increased pulmonary blood flow Prominent ascending aorta and pulmonary artery AORTICO-PULMONARY WINDOW IMAGING Cross sectional imaging MRI and CT can depict APW anatomy Used as adjunct to echo Shunt volume quantification Ventricular function evaluation Angiocardiography Confirm Dx if echo questioned Used if pulmonary pressures are needed to be determined Critical to differentiate from truncus arteriosus (APW has two distinct semilunar valves) SUMMARY Echocardiography Mainstay MRI / CT Complicated cases Also yields good physiological information CXR Useful for screening Angiography Complicated lesions Usually used where catheter angio intervention is planned RESOURCES Caf fey’s Pediatric Diagnostic Imaging 11 th ed – Slovis Classic Imaging Signs of Congenital Cardiovascular Abnormalities – Ferguson et al - September 2007RadioGraphics, 27, 1323-1334. http://www.yale.edu/imaging Thank you