How to Assess and Treat Obstructive Lesions Erwin Oechslin, MD, FESC, FRCPC, Director, Congenital Cardiac Centre for Adults Peter Munk Cardiac Centre University Health Network/Toronto General Hospital Toronto, ON, Canada
Outline Background Diagnostic Work-Up General Principles Doppler echocardiography CMR / CT Exercise testing Specific Lesions LVOT obstruction Right ventricular outflow tract obstruction
BACKGROUND RIGHT and LEFT ventricular outflow tract obstructions are common Simple vs complex Level of obstruction Subvalvular Valvular Supravalvular Combined lesions
Diagnostic Work-Up (1) GENERAL PRINCIPLES Comprehensive CLINICAL assessment Medical history Family history! Learning difficulties! Physical examination Murmurs / ejection click? BD difference upper and lower extremities / brachiofemoral pulse delay Syndromic appearance Turner / Noonan syndrome, microdeletion 22q11.2 syndrome amongst others
Diagnostic Work-Up (2) GENERAL PRINCIPLES Non-invasive imaging Chest X-ray (not routinely; when clinically indicated) Doppler echocardiography Cardiovascular MR (CMR) Computed tomography (CT) Exercise testing Diagnostic heart catheterization To verify the gradients across the LVOT / RVOT
Doppler Echocardiography (1) FIRST LINE NON-INVASIVE INVESTIGATION Anatomy / morphology (intracardiac!) Type of obstruction Level of obstruction (isolated/multiple levels) Functional assessment Diameters / volumes (left ventricle) Ventricular hypertrophy (concentric vs eccentric) Ventricular function (systolic and diastolic function) GRADIENTS across RVOT / LVOT Fixed vs dynamic obstruction RV systolic pressure
Doppler Echocardiography (2) LIMITATIONS and PRECAUTIONS Investigator dependence Expertise in CHD is required! Poor window / echo quality Doppler gradients can be misleading RVOT obstruction; serial stenoses at multiple levels Tubular stenosis (aortic coarctation/conduits) Pressure recovery Modified Bernoulli equation does not apply to tubular stenosis / stenoses in series RVSP is more accurate to estimate severity of RVOT obstruction
Specific Indications for CMR CMR is Superior to Echocardiography RVOT obstruction RV to PA conduits Extracardiac anatomy Pulmonary arteries (peripheral PA stenosis, aneurysm) Aorta (supravalvular AS, aortic coarctation, aneurysm, dissection)
Exercise Testing Important role in the timing of interventions and reinterventions in asymptomatic patients Asymptomatic Patient Exercise Testing* Normal *Symptoms Inadequate BP response Regular Follow-up Intervention
Outline Background Diagnostic Work-Up General Principles Doppler echocardiography CMR / CT Exercise testing Specific Lesions LVOT obstruction Right ventricular outflow tract obstruction
Left Ventricular Outflow Tract Obstruction Level of obstruction: Subvalvular Valvular (75%) Supravalvular
Subaortic Stenosis (1) BACKGROUND Presentation Isolated Associated defects: VSD, AVSD, conotruncal anomalies Shone complex! Prevalence: 6-7% in GUCH population Morphologic appearance Fibrous ridge Fibromuscular narrowing Differential: HCM
General Principles Subaortic Stenosis (2) DIAGNOSTIC WORK-UP Doppler Echocardiography Morphology / associated congenital anomalies(!) Functional assessment: Overestimation / underestimation of the gradient (tubular stenosis / localization of VSD) Aortic regurgitation TEE / 3-D echocardiography: to characterize complex anatomy of the LVOT
Subaortic Stenosis (3) INDICATIONS FOR INTERVENTION Peak gradient >50 / mean gradient >30 mmhg Symptoms?? Symptoms and peak gradient >50mmHg or mean gradient >30 mmhg or If combined with progressive AR
Subaortic Stenosis (3) INDICATIONS FOR INTERVENTION Peak gradient <50 / mean grad. <30mmHg and progressive AR and LV-ESD > 50 mm and LV-EF <55% Class I C????????
Subaortic Stenosis (4) INDICATIONS FOR INTERVENTION?? Mean grad. of 30mmHg Class IIb C Mean grad.<30mmhg, if LV hypertrophy Pregnancy considered Strenuous exercise Class IIb C Trivial SAS to prevent AR Class III C????????
Supravalvular Aortic Stenosis (1) BACKGROUND Rare (<7% of all fixed forms of LVOTO) Morphologic appearance: Localized fibrous diaphragm (distal to ostia of the coronary arteries) External hourglass deformity with luminal narrowing Diffuse stenosis of the ascending aorta Association with Williams-Beuren syndrome Diffuse hypoplasia of the entire aorta Involvement of coronary arteries Stenosis of major branches of the aorta/pas
Supravalvular Aortic Stenosis (2) DIAGNOSTIC WORK-UP General Principles Doppler echocardiography CMR Anatomic description Overestimation of the gradient! Precise anatomic description Identification of additional lesions (branches of the aorta/pas/renal arteries Exercise testing
Supravalvular AS (4) INDICATIONS FOR INTERVENTION????
Supravalvular AS (5) INDICATIONS FOR INTERVENTION??????
Aortic Coarctation (1) BACKGROUND Generalized AORTOPATHY! Cystic media necrosis with increased stiffness of the aorta and carotid arteries Aortic dilatation Endothelial dysfunction Morphologic appearance: Discrete narrowing Diffuse hypoplasia / geometry of the aortic arch
Aortic Coarctation (2) BACKGROUND Presentation: Isolated Associated CHD: Bicuspid aortic valve (up to 85%) Shone complex! Turner syndrome Williams-Beuren syndrome Congenital Rubella syndrome Non-congenital pathologies: Takayasu-arteritis, trauma
Aortic Coarctation (3) DIAGNOSTIC WORK-UP Specific considerations Hemodynamically relevant aortic coarctation: BP difference > 20 mmhg between right arm and lower extremities Brachio-femoral pulse delay Palpable collaterals Chest X-Ray: Rib-notching Kinking / double contouring of the descending aorta (figure -3 sign) Dilatation of ascending aorta
Aortic Coarctation (4) DIAGNOSTIC WORK-UP Doppler Echocardiography Gradients are not useful! Tubular stenosis Aortic collaterals in native aortic coarctation Increased systolic flow velocity due to the lack of aortic compliance after repair even in the absence of stenosis Diastolic run-off : most reliable sign for significant aortic coarctation
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Aortic Coarctation (6) DIAGNOSTIC WORK-UP CMR / CT Preferred diagnostic modality to evaluate the entire aorta (geometry of the arch!) Detection Site, extent, and degree of stenosis (collaterals!) Complications after repair (aneurysm, re-stenosis)
Native aortic coarctation
Aortic Coarctation (6) DIAGNOSTIC WORK-UP Cardiac Catheterization Reference method to evaluate severity of aortic coarctation Hemodynamically relevant stenosis Peak-to-peak gradient >20 mmhg in the absence of well-developed collaterals
Aortic Coarctation (7) INDICATIONS FOR INTERVENTION Class a Level b All patients with a non-invasive pressure difference > 20 mmhg between upper and lower limbs, regardless of symptoms but with upper limb hypertension (> 140/90 mmhg in adults), pathologic blood pressure response during exercice, or significant LVH should have intervention I C Peak to peak grad > 20mmHg Peak to peak grad < 20 mmhg if significant collaterals Peak to peak grad > 20mmHg and hypertension PG < 20 mmhg and collateral flow!
Aortic Coarctation (9) SURGERY vs BALLOON DILATATION/STENT Aortic coarctation Native coarctation Recurrent/residual aortic coarctation Anatomy suitable? No Yes Surgery Balloon/stent
Aortic Coarctation (9) CO-MORBIDITIES Aortic stenosis / regurgitation (bicuspid aortic valve!) Aneurysm of the ascending aorta Diameter > 50 mm or 27.5 mm/m 2 Aneurysm at previous aortic site Aneurysm of the circle of Willis
Aortic Coarctation (10) FOLLOW-UP At least every 2 years at a GUCH centre Long term complications Arterial hypertension (geometry of the aortic arch normal, gothic, crenel may play a role) Role of exercise induced hypertension? Recurring or residual aortic coarctation Aneurysm of the ascending aorta or at the intervention site (patch repair!) risk for rupture/death Aortic valve anomaly / Shone complex Aneurysm of the circle of Willis
Outline Background Diagnostic Work-Up General Principles Doppler echocardiography CMR / CT Exercise testing Specific Lesions LVOT obstruction Right ventricular outflow tract obstruction
RVOT Obstruction (1) BACKGROUND Level of stenosis Subinfundibular: associated with VSD! Infundibular: secondary to valvular PS or associated with VSD (!), TOF Dynamic obstruction Valvular: 7-12% of all CHDs Intrinsic pulmonary wall abnormality Supravalvular: isolated (seldom) or associated with syndromes Noonan, Williams-Beuren, Keutel, congenital Rubella syndrome
RVOT Obstruction (2) NATURAL HISTORY Mild valvular PS does not progress Progressive stenosis Infundibular stenosis Moderate valvular stenosis (calcification of the cusps) Reactive infundibular hypertrophy with dynamic obstruction of the RVOT Supravalvular PS
Chest X-ray RVOT Obstruction (3) DIAGNOSIC WORK-UP Calcification of the cups Dilatation of pulmonary trunk / right heart Doppler echocardiography - Pitfalls Overestimation of the gradient (!) Stenoses in series / tubular stenosis Contamination with VSD jet Underestimation of the gradient (!) Doppler probe is not aligned to blood flow (e.g. double chambered RV)
Subvalvular and Valvular PS
RVOT Obstruction (4) HOW TO ASSESS SEVERITY? Severity based on peak gradient across RVOT mild (peak gradient < 36 mm Hg, peak velocity < 3m/s) moderate (36 to 64 mm Hg; 3-4 m/s) severe (>64 mm Hg, peak velocity >4m/s) TR velocity with estimation of RV systolic pressure should always be used in addition when assessing severity
RVOT Obstruction (5) DIAGNOSTIC WORK-UP CMR / CT Infundibular and supravalvular/peripheral PS (Assessment of conduits) Dilatation of PAs Differential blood flow to the right/left lung (Nuclear techniques) Differential blood flow to the right/left lung Catheterization Confirmation of the level and severity of stenosis
RVOT Obstruction (6) INDICATIONS FOR INTERVENTION Balloon dilatation Pulmonary valvular stenosis (nondysplastic pulmonic valve) Peripheral PS (balloon dilatation plus stent) Surgery Infundibular stenosis Severely dysplastic pulmonic valve Hypoplastic pulmonic annulus Associated lesions requiring surgery (severe PR, TR)
RVOT Obstruction (7) INDICATIONS FOR INTERVENTION VALVULAR PS: Symptoms: PG / MG >50/>30 mmhg Less than moderate PR No Symptoms: PG / MG >60/>40 mmhg and less than moderate PR
VALVULAR PS (8) BALLOON VALVOTOMY vs SURGERY ASYMPTOMATIC Valvular PS Suitable for Balloon Valvuloplasty? YES NO PVR is the only option Balloon Valvuloplasty when PG > 64 mmhg Class I C Surgery when RVSP > 80 mmhg TR velocity > 4.3 m/sec
Summary Comprehensive assessment Clinical assessment Non-invasive +/- invasive imaging Exercise testing Critical interpretation of Doppler gradients! RVSP is more accurate to estimate severity of RVOTO Guidelines are a useful handbook. It is the cook who makes the difference