Fuad Fuad FarooqFarooq

Pulmonary Stenosis (PS) has been Pulmonary Stenosis (PS) has been described in 1761 by Morgagnidescribed in 1761 by Morgagni

It accounts for 20-30% of all CHD It accounts for 20-30% of all CHD Found in 8% to 10% of patients as isolated Found in 8% to 10% of patients as isolated

PSPS In 50% of cases the septum is intactIn 50% of cases the septum is intact

Three anatomical varientsThree anatomical varients

Valvar (90%)Valvar (90%)

Subvalvar (Subvalvar (Infundibular stenosis from Infundibular stenosis from

hypertrophy of the Crista hypertrophy of the Crista

Supraventricularis)Supraventricularis)

Supravalvar (pulmonary artery trunk or Supravalvar (pulmonary artery trunk or

branches )branches )

Pulmonary valve stenosis is usually Pulmonary valve stenosis is usually isolated or part of the complex congenital isolated or part of the complex congenital heart diseaseheart disease

Exact embryologic process is not well Exact embryologic process is not well understoodunderstood

Mal-development of the distal part of the bulbus Mal-development of the distal part of the bulbus cordis cordis

Genetic factors may play a roleGenetic factors may play a role Known association between pulmonary valve and Known association between pulmonary valve and

supravalvular stenosis with multiple somatic supravalvular stenosis with multiple somatic abnormalities abnormalities

Valve commisures are partially fused and the 3 Valve commisures are partially fused and the 3 leaflets are thin and pliant, resulting in a conical leaflets are thin and pliant, resulting in a conical or dome-shaped structure with a narrowed or dome-shaped structure with a narrowed central orifice central orifice

It may be diffusely thickened with one, two, or It may be diffusely thickened with one, two, or three leaflets and commissural fusionthree leaflets and commissural fusion

Bicuspid valve is found in 90% of patients Bicuspid valve is found in 90% of patients with Tetralogy of Fallotwith Tetralogy of Fallot Rare in individuals with isolated valvular PSRare in individuals with isolated valvular PS

10-15% of individuals with valvular PS have 10-15% of individuals with valvular PS have dysplastic pulmonary valvesdysplastic pulmonary valves

Valves have irregularly shaped, thickened leaflets, Valves have irregularly shaped, thickened leaflets, with little commissural fusion and exhibit reduced with little commissural fusion and exhibit reduced mobilitymobility

The leaflets are composed of myxomatous tissue, The leaflets are composed of myxomatous tissue, which may extend to the vessel wallwhich may extend to the vessel wall

The valve annulus is usually small and the The valve annulus is usually small and the supravalvular area of the pulmonary trunk is usually supravalvular area of the pulmonary trunk is usually hypoplastichypoplastic

Poststenotic dilatation of the pulmonary artery is Poststenotic dilatation of the pulmonary artery is uncommonuncommon

Secondary changes in the right ventricle and Secondary changes in the right ventricle and pulmonary arteriespulmonary arteries

Right ventricle espacially infundibular region Right ventricle espacially infundibular region becomes diffusely hypertrophiedbecomes diffusely hypertrophied Produce dynamic subvalvular obstructionProduce dynamic subvalvular obstruction

Right atrium may be thick and dilate as a Right atrium may be thick and dilate as a result of the increased pressure necessary result of the increased pressure necessary to fill the hypertrophic right ventricleto fill the hypertrophic right ventricle

Rise in RV pressure proportional to the Rise in RV pressure proportional to the severity of obstructionseverity of obstruction

Increase in muscle massIncrease in muscle mass Hyperplasia of the muscle cells with a Hyperplasia of the muscle cells with a

concomitant increase in the number of capillaries concomitant increase in the number of capillaries

Increased muscle mass may enable the Increased muscle mass may enable the hypertensive right ventricle to maintain a hypertensive right ventricle to maintain a normal stroke volumenormal stroke volume

Development of poststenotic dilation of Development of poststenotic dilation of the pulmonary artery trunk sometimes the pulmonary artery trunk sometimes extending to the proximal left pulmonary extending to the proximal left pulmonary arteryartery

Result from the high velocity jet of flow ejected Result from the high velocity jet of flow ejected through the small valve orifice - “jet effect”through the small valve orifice - “jet effect”

The degree of dilation is not necessarily The degree of dilation is not necessarily proportional to the severity of obstructionproportional to the severity of obstruction

RV eventually dilate and failRV eventually dilate and fail

Exacerbated by:Exacerbated by: Development of tricuspid insufficiencyDevelopment of tricuspid insufficiency

Subendocardial (esp. at infundibular region) and Subendocardial (esp. at infundibular region) and papillary muscle ischemia/infarction papillary muscle ischemia/infarction

Mostly diagnosis is made when murmur Mostly diagnosis is made when murmur detected in asymptomatic patients on routine detected in asymptomatic patients on routine examinationexamination

Exertional dyspnea, fatigue and cynosis due Exertional dyspnea, fatigue and cynosis due to inability of the right ventricle to increase its to inability of the right ventricle to increase its output in response to exertionoutput in response to exertion

If the stenosis is not relieved then features of If the stenosis is not relieved then features of right heart failureright heart failure

Chest pain, syncope and sudden death with strenuous exerciseChest pain, syncope and sudden death with strenuous exercise

Decreased myocardial perfusion caused by Decreased myocardial perfusion caused by inadequate cardiac output during exercise, inadequate cardiac output during exercise, leading to ischemia and ventricular arrhythmiasleading to ischemia and ventricular arrhythmias

‘‘a’ wave becomes progressively larger a’ wave becomes progressively larger with increasing severity of obstructionwith increasing severity of obstruction

Left parasternal heave Left parasternal heave Systolic thrill in severe pulmonary Systolic thrill in severe pulmonary

stenosisstenosis Located at the 2Located at the 2ndnd to 3 to 3rdrd intercostal space intercostal space

but it may also be felt at the suprasternal but it may also be felt at the suprasternal notchnotch

Absent in young infants with severe stenosis Absent in young infants with severe stenosis and in patients with congestive heart failure and in patients with congestive heart failure and low cardiac outputand low cardiac output

S1 normal followed by a pulmonary S1 normal followed by a pulmonary ejection click in patients with mild or ejection click in patients with mild or moderate stenosismoderate stenosis

Corresponds to the time when the doming Corresponds to the time when the doming pulmonary valve reaches its open positionpulmonary valve reaches its open position

Become earlier as severity increased until it Become earlier as severity increased until it merges with the first heart sound and merges with the first heart sound and becomes inaudiblebecomes inaudible

Click is followed by ESM maximal at the Click is followed by ESM maximal at the upper left sternal borderupper left sternal border

Intensity – increases with the severity of obstructionIntensity – increases with the severity of obstruction

Radiation – entire precordium, neck & back Radiation – entire precordium, neck & back (characteristically)(characteristically)

Become soft when severe stenosis with right heart Become soft when severe stenosis with right heart failure due to low cardiac outputfailure due to low cardiac output

P2 intensity typically decreases with P2 intensity typically decreases with increase severity of obstructionincrease severity of obstruction

S4 – lower left sternal border in patients with S4 – lower left sternal border in patients with severe stenosissevere stenosis

Pansystolic murmur of tricuspid insufficiency Pansystolic murmur of tricuspid insufficiency may be present lower along the left sternal may be present lower along the left sternal borderborder

S3 – when present think of ASDS3 – when present think of ASD

Mild stenosis usually have a normal Mild stenosis usually have a normal electrocardiogram electrocardiogram

Rightward axis deviation is often the only abnormalityRightward axis deviation is often the only abnormality

Electrocardiogram is almost always Electrocardiogram is almost always abnormalabnormal

Right axis deviationRight axis deviation

The R:S ratio in V1 is usually >4:1The R:S ratio in V1 is usually >4:1

R wave is typically <20 mmR wave is typically <20 mm

The T waves in the right precordial leads are The T waves in the right precordial leads are upright in approximately 50% of patientsupright in approximately 50% of patients

QRS axis >110 degrees and not uncommonly extreme QRS axis >110 degrees and not uncommonly extreme RAD RAD

A pure R, Rs, or QR is the usual pattern in the right A pure R, Rs, or QR is the usual pattern in the right precordial leads, and the R wave is usually >20 mmprecordial leads, and the R wave is usually >20 mm

The R:S ratio in VThe R:S ratio in V66 may be <1.0 may be <1.0

The T waves usually inverted in the right precordial leadsThe T waves usually inverted in the right precordial leads

P-pulmonale indicating right atrial enlargementP-pulmonale indicating right atrial enlargement

Estimation of RV pressure is possibe if a pure R Estimation of RV pressure is possibe if a pure R wave is present in lead Vwave is present in lead V4R4R or V or V11

The height of the R wave in millimeters, The height of the R wave in millimeters, multiplied by 5, approximates the right multiplied by 5, approximates the right ventricular pressure in mm of Hgventricular pressure in mm of Hg

Enlarged main pulmonary artery secondary to Enlarged main pulmonary artery secondary to

post-stenotic dilatationpost-stenotic dilatation

Enlarged left pulmonary artery (jet stream effect)Enlarged left pulmonary artery (jet stream effect)

Normal to decreased peripheral pulmonary Normal to decreased peripheral pulmonary

vasculaturevasculature

Cardiomegaly Cardiomegaly

Results from RA and RV enlargementResults from RA and RV enlargement

Standard and high parasternal short and long axis views Standard and high parasternal short and long axis views and the subcostal sagittal viewsand the subcostal sagittal views

Valve leaflets usually appear prominent because of Valve leaflets usually appear prominent because of thickeningthickening

Systolic motion is restricted, with inward curving of the Systolic motion is restricted, with inward curving of the tips of the leaflets, known as domingtips of the leaflets, known as doming

Poststenotic dilation of the main and branch pulmonary Poststenotic dilation of the main and branch pulmonary arteries are also easily recognizedarteries are also easily recognized

Assessment of RV anatomy and function and assessment Assessment of RV anatomy and function and assessment of tricuspid valve of tricuspid valve

Evidence of dynamic subpulmonary stenosis should be Evidence of dynamic subpulmonary stenosis should be soughtsought

Dysplastic pulmonary valve usually can be ascertained by Dysplastic pulmonary valve usually can be ascertained by echocardiographyechocardiography The leaflets appear thickened and immobile, without the The leaflets appear thickened and immobile, without the

characteristic doming seen in typical casescharacteristic doming seen in typical cases The pulmonary valve annulus is hypoplastic, and supra-annular The pulmonary valve annulus is hypoplastic, and supra-annular

narrowing of the proximal main pulmonary artery is often presentnarrowing of the proximal main pulmonary artery is often present Poststenotic pulmonary artery dilation seen in classic cases is Poststenotic pulmonary artery dilation seen in classic cases is

absentabsent

Allows quantitative assessment of severity of Allows quantitative assessment of severity of pulmonary valve stenosispulmonary valve stenosis

The echo beam must be aligned parallel with the The echo beam must be aligned parallel with the main pulmonary artery trunk or the direction of the main pulmonary artery trunk or the direction of the flow jet as seen on color Dopplerflow jet as seen on color Doppler

Excellent correlation between the Doppler-derived Excellent correlation between the Doppler-derived gradient and that obtained by direct pressure gradient and that obtained by direct pressure measurement at catheterizationmeasurement at catheterization

Role of catheterization has become largely Role of catheterization has become largely limited in therapeuticslimited in therapeutics

Measurement of RV pressure and Measurement of RV pressure and compared with systemic arterial pressure compared with systemic arterial pressure and the pressure gradient across the and the pressure gradient across the pulmonary valvepulmonary valve

Resting RV pressure >30 to 35 mm Hg and Resting RV pressure >30 to 35 mm Hg and pressure gradient across the pulmonary pressure gradient across the pulmonary valve of >10 are considered abnormalvalve of >10 are considered abnormal

RV pressures 105 mmHg and PA pressures are 60, so the gradient is 45 mmHg

If associated infundibular obstruction, pressure If associated infundibular obstruction, pressure gradients are encountered across the pulmonary gradients are encountered across the pulmonary valve and also across the infundibulumvalve and also across the infundibulum

RVEDP may be normal but usually elevated with RVEDP may be normal but usually elevated with severe obstruction or right ventricular failuresevere obstruction or right ventricular failure

Right atrial pressure is normal in mild to moderate Right atrial pressure is normal in mild to moderate obstruction, but tall right atrial ‘A’ waves usually obstruction, but tall right atrial ‘A’ waves usually are seen with severe obstructionare seen with severe obstruction

Provides information about the location and Provides information about the location and severity of pulmonary stenosis that is severity of pulmonary stenosis that is invaluable for diagnostic and therapeutic invaluable for diagnostic and therapeutic purposespurposes

Anatomy of the pulmonary valve and Anatomy of the pulmonary valve and associated features can be shown best by associated features can be shown best by right ventricular angiography in the right ventricular angiography in the anteroposterior cranial and lateral view anteroposterior cranial and lateral view

Normal pulmonary valve area is 2.0 cmNormal pulmonary valve area is 2.0 cm22/m/m2 2 of BSAof BSA

Mild stenosis- Valve area larger than 1 cm2

- Right ventricular pressure less than half the left ventricular pressure- Peak gradient 10-35 mm Hg- Peak velocity <3m/sec

Moderate stenosis- Valve area 0.5-1.0 cm2

- Right ventricular pressure is greater than half but <75% of the left ventricular pressure- Peak gradient is 36-64 mm Hg- Peak velocity 3-4m/sec

Severe stenosis- Valve area <0.5cm2

-Right ventricular pressure 75% of the left ventricular pressure - Peak gradient >64 mm Hg- Peak velocity >4/sec

Idiopathic dilation of the main pulmonary arteryIdiopathic dilation of the main pulmonary artery ASDASD Peripheral pulmonary arterial stenosisPeripheral pulmonary arterial stenosis Mitral valve prolapseMitral valve prolapse Straight back syndromeStraight back syndrome Aortic stenosisAortic stenosis Innocent murmursInnocent murmurs VSD with or without associated pulmonary stenosisVSD with or without associated pulmonary stenosis Tetralogy of Fallot Tetralogy of Fallot Pulmonary atresia with intact ventricular septum Pulmonary atresia with intact ventricular septum Ebstein anomaly of the tricuspid valveEbstein anomaly of the tricuspid valve

Noonan syndrome in 50% of patientsNoonan syndrome in 50% of patients Most common lesion is pulmonary stenosis owing to pulmonary valve Most common lesion is pulmonary stenosis owing to pulmonary valve

dysplasiadysplasia

25% of Hypertrophic CMP of the left ventricle with PS25% of Hypertrophic CMP of the left ventricle with PS

Rarely - cardiac tumors can grow on or into the RV outflow tract Rarely - cardiac tumors can grow on or into the RV outflow tract and cause flow obstructionand cause flow obstruction

Extrinsic lesions e.g., Sinus of Valsalva aneurysms and aortic Extrinsic lesions e.g., Sinus of Valsalva aneurysms and aortic graft aneurysms compressing cardiac structures and can cause graft aneurysms compressing cardiac structures and can cause PSPS

Multiple lentigines syndrome, or leopard syndrome, has been Multiple lentigines syndrome, or leopard syndrome, has been associated with pulmonary valve and pulmonary artery stenosisassociated with pulmonary valve and pulmonary artery stenosis

Neurofibromatosis, deposits from glycogen storage Neurofibromatosis, deposits from glycogen storage diseases and goutdiseases and gout

Carcinoid results in development of myxomatous Carcinoid results in development of myxomatous (fibroelastic) plaques in the RV outflow tract(fibroelastic) plaques in the RV outflow tract Distortion and constriction of the pulmonic ring, as well as fusion Distortion and constriction of the pulmonic ring, as well as fusion

or destruction of pulmonary valve leaflets, resulting in both or destruction of pulmonary valve leaflets, resulting in both stenosis and regurgitation stenosis and regurgitation

Rare manifestation of rheumatic heart disease - follows Rare manifestation of rheumatic heart disease - follows involvement of the mitral and aortic valvesinvolvement of the mitral and aortic valves

Valvuloplasty should be performed in any Valvuloplasty should be performed in any symptomatic patient as soon as the diagnosis is symptomatic patient as soon as the diagnosis is mademade

Immediate valvoplasty in infants with critical Immediate valvoplasty in infants with critical pulmonary valve stenosispulmonary valve stenosis

Asymptomatic patients with severe obstruction Asymptomatic patients with severe obstruction should be treated semielectively with should be treated semielectively with valvuloplasty shortly after diagnosisvalvuloplasty shortly after diagnosis

Moderate obstruction should undergo elective Moderate obstruction should undergo elective valvuloplasty if the right ventricular pressure is 50% valvuloplasty if the right ventricular pressure is 50% systemic or highersystemic or higher

No intervention is necessary for patients with mild No intervention is necessary for patients with mild obstructionobstruction They should not be restricted in their physical activity and They should not be restricted in their physical activity and

should be treated as normal childrenshould be treated as normal children

Endocarditis prophylaxis is not recommended for Endocarditis prophylaxis is not recommended for patients with pulmonary valve stenosispatients with pulmonary valve stenosis

Described initially by Kan and associates in 1982 Described initially by Kan and associates in 1982 After obtaining appropriate hemodynamic and After obtaining appropriate hemodynamic and

angiographic information about severity and location of angiographic information about severity and location of obstruction, an exchange guidewire is introduced through obstruction, an exchange guidewire is introduced through an end-hole catheter and positioned in the distal left an end-hole catheter and positioned in the distal left pulmonary arterypulmonary artery

A balloon is chosen that is 20% to 40% larger than the A balloon is chosen that is 20% to 40% larger than the angiographically measured pulmonary valve annulus, angiographically measured pulmonary valve annulus, and it is positioned over a guidewire with the valve at its and it is positioned over a guidewire with the valve at its midpointmidpoint

In larger patients with an annulus diameter of >20 mm, In larger patients with an annulus diameter of >20 mm, the double-balloon technique may be necessary, with the double-balloon technique may be necessary, with simultaneous inflation of two angioplasty balloonssimultaneous inflation of two angioplasty balloons

Independent predictors of suboptimal Independent predictors of suboptimal intermediate-term outcomeintermediate-term outcome

Small annular size (characteristic of patients Small annular size (characteristic of patients with dysplastic valves)with dysplastic valves)

Higher immediate residual gradientHigher immediate residual gradient Earlier year of the initial valvuloplastyEarlier year of the initial valvuloplasty Smaller balloon to annulus ratioSmaller balloon to annulus ratio

Death (0.2%)Death (0.2%) Laceration of the inferior vena cava, iliac vein junction Laceration of the inferior vena cava, iliac vein junction

during balloon withdrawal during balloon withdrawal Tearing of the pulmonary valve annulus during balloon Tearing of the pulmonary valve annulus during balloon

inflationinflation

Perforation of the right ventricular outflow tract Perforation of the right ventricular outflow tract resulting in tamponade and tricuspid regurgitation resulting in tamponade and tricuspid regurgitation requiring surgical interventionrequiring surgical intervention

Vein thrombosis and vein tearsVein thrombosis and vein tears

Arrhythmias (1.3%)Arrhythmias (1.3%)

Stroke, seizures, necrotizing enterocolitis, endocarditis Stroke, seizures, necrotizing enterocolitis, endocarditis and septic shockand septic shock

Abrupt closure of the ductus despite prostaglandin Abrupt closure of the ductus despite prostaglandin infusion requiring urgent aortopulmonary shunt infusion requiring urgent aortopulmonary shunt placementplacement

Pulmonary insufficiency Pulmonary insufficiency Risk factors: smaller body surface area at the time of Risk factors: smaller body surface area at the time of

intervention, larger balloon to annulus ratio and a higher intervention, larger balloon to annulus ratio and a higher degree of obstruction before dilationdegree of obstruction before dilation

Tends to progress with timeTends to progress with time

Reserved for dysplastic pulmonary valves resistant to Reserved for dysplastic pulmonary valves resistant to dilation or with multiple levels of fixed obstructiondilation or with multiple levels of fixed obstruction

Often a persistent pressure gradient immediately after Often a persistent pressure gradient immediately after surgery in patients with isolated valvar pulmonary surgery in patients with isolated valvar pulmonary stenosis attributable to dynamic narrowing of the stenosis attributable to dynamic narrowing of the hypertrophied infundibulum (as also observed following hypertrophied infundibulum (as also observed following balloon valvuloplasty)balloon valvuloplasty)

Reduction in gradient occur in the first 24 hours after Reduction in gradient occur in the first 24 hours after surgery and continues at a slower rate as the surgery and continues at a slower rate as the hypertrophy resolves over the subsequent monthshypertrophy resolves over the subsequent months

Presence of symptoms such as progressive Presence of symptoms such as progressive decrease in exercise tolerance or functional decrease in exercise tolerance or functional class or evidence of right heart failure class or evidence of right heart failure

Progressive RV enlargement often accompanied Progressive RV enlargement often accompanied by increasing TR owing to annular dilation by increasing TR owing to annular dilation

Development or progression of atrial and/or Development or progression of atrial and/or ventricular arrhythmias ventricular arrhythmias

Homograft valves, xenograft valves, Homograft valves, xenograft valves, pericardial valves, and mechanical valvespericardial valves, and mechanical valves

Percutaneous pulmonary valve Percutaneous pulmonary valve replacement with a bovine jugular venous replacement with a bovine jugular venous valve sutured inside a stent was first valve sutured inside a stent was first described in a human in 2000described in a human in 2000

Symptoms are unreliable in reflecting Symptoms are unreliable in reflecting hemodynamic severity because they hemodynamic severity because they usually are seen only in patients with usually are seen only in patients with severe or critical obstruction severe or critical obstruction

The course of mild stenosis is benignThe course of mild stenosis is benign No intervention is requiredNo intervention is required The hemodynamic response to exercise in The hemodynamic response to exercise in

these patients is normal these patients is normal

Patients with moderate stenosis may develop Patients with moderate stenosis may develop progressively greater outflow tract obstruction, progressively greater outflow tract obstruction, especially during periods of rapid growthespecially during periods of rapid growth

In most asymptomatic patients with moderate In most asymptomatic patients with moderate

pulmonary valve stenosis formal exercise testing pulmonary valve stenosis formal exercise testing demonstrated subnormal cardiac output response demonstrated subnormal cardiac output response and abnormal increase in right ventricular end-and abnormal increase in right ventricular end-diastolic pressure suggesting that both systolic and diastolic pressure suggesting that both systolic and diastolic dysfunction may be caused by long-standing diastolic dysfunction may be caused by long-standing moderate obstructionmoderate obstruction

Children with severe stenosis commonly Children with severe stenosis commonly develop increasingly severe obstructiondevelop increasingly severe obstruction Result from disproportionate growth of the child Result from disproportionate growth of the child

relative to the pulmonary valve relative to the pulmonary valve

Exercise hemodynamics in children and adults Exercise hemodynamics in children and adults with severe obstruction before and after with severe obstruction before and after valvotomy suggest that irreversible changes in valvotomy suggest that irreversible changes in cardiac function can develop if treatment is cardiac function can develop if treatment is delayed beyond childhood delayed beyond childhood

Patients with severe stenosis have a lower cardiac stroke Patients with severe stenosis have a lower cardiac stroke index at rest and during exercise and also higher RVEDP index at rest and during exercise and also higher RVEDP at rest and abnormal increase with exercise than patients at rest and abnormal increase with exercise than patients with milder diseasewith milder disease

Following valvotomy there is an improvement in stroke Following valvotomy there is an improvement in stroke index and reduction in RVEDP at rest and during exercise index and reduction in RVEDP at rest and during exercise within 1 year of operationwithin 1 year of operation

In contrast this improvement is not observed in older In contrast this improvement is not observed in older patientspatients Implying permanent changes e.g., myocardial fibrosis have Implying permanent changes e.g., myocardial fibrosis have

occurredoccurred Hence relief of severe pulmonary valve stenosis without undue Hence relief of severe pulmonary valve stenosis without undue

delay is recommended delay is recommended

5% of all cases of right ventricular outflow tract 5% of all cases of right ventricular outflow tract obstruction obstruction

Two types: Two types: Obstructive fibrous band at the junction of the main Obstructive fibrous band at the junction of the main

right ventricular cavity and the proximal infundibulum right ventricular cavity and the proximal infundibulum that closely resembles double-chambered right that closely resembles double-chambered right ventricle ventricle

Narrowing of the infundibulum is due to Narrowing of the infundibulum is due to fibromuscular thickening of its wall, which may fibromuscular thickening of its wall, which may extend from immediately below the pulmonary valve extend from immediately below the pulmonary valve to the proximal infundibulumto the proximal infundibulum

““Double-chambered right ventricle“Double-chambered right ventricle“

Aberrant hypertrophied muscular bands - divide the RV Aberrant hypertrophied muscular bands - divide the RV cavity into a proximal high-pressure chamber and a distal cavity into a proximal high-pressure chamber and a distal low-pressure chamber to the hypertrophied muscle bands low-pressure chamber to the hypertrophied muscle bands

Orientation differs from that of the moderator bandOrientation differs from that of the moderator band Septal attachment of the moderator band is usually in the apical Septal attachment of the moderator band is usually in the apical

third of the ventricular septumthird of the ventricular septum Septal attachment of anomalous muscle bundles are near the Septal attachment of anomalous muscle bundles are near the

base of the tricuspid valve ringbase of the tricuspid valve ring

Visualized best from – subcostal and Visualized best from – subcostal and parasternal views parasternal views

Presence or absence of a ventricular septal Presence or absence of a ventricular septal defect can be documenteddefect can be documented

Abnormal fluttering of the pulmonary valve is Abnormal fluttering of the pulmonary valve is often a concomitant findingoften a concomitant finding

Treatment is surgical correctionTreatment is surgical correction