Imaging of Repaired Tetralogy of Fallot in Adults...Imaging of Repaired Tetralogy of Fallot in...

Imaging of Repaired Tetralogy of Fallot in Adults

SURGICAL MORPHOLOGY and IMAGING of CONGENITAL HEART DISEASE WORKSHOP

22nd SEPTEMBER , 2016

Tan Ju-Le MBBS, MRCP, FAMS, FACC, FESC

Director, Senior Consultant Cardiologist Adult Congenital Heart Disease Program

National Heart Centre SINGAPORE

Imaging of Repaired TOF in adults • What constitutes a repaired TOF?

• TOF Anatomy and Surgical Repair

• Echo assessment of repaired TOF patients • Residual Lesions • Sequlae of the repair • PR severity • RV function

• MRI assessment of Post op TOF patients

• CT assessment of Post op TOF patients

• The anterior and cranial displacement of the infundibular septum causes some degree of RVOT obstruction and mal-aligned VSD with overriding aorta • RVH follows from the RVOT obstruction • Made up of 4 defects

Overriding aorta Ventricular Septal Defect

(VSD) RVOT obstruction ±

Pulmonary Stenosis Right Ventricular

Hypertrophy (RVH)

TOF Anatomy

Very rarely, we still see adult patients presenting for the first time with unrepaired TOF This 33 year old lady with uncorrected TOF, lost to follow up, recently referred bec of increasing SOB; getting married next year and planning to have children

TOF Repair

TOF Surgical Repair a) Ventriculotomy approach In patient with severe RVOT obstruction b) Pericardial patch to RVOT c) Transannular pericardial patch d) Bicuspid PV and hypoplastic main PA e) Patch augmentation of RVOT and mPA R. Jonas : Semin Thorac Cardiovasc Surg Pediatr Card Surg Ann 12:39-47, 2009.

Reason for PR post surgical repair of TOF

• If pulmonary annulus is hypoplastic and disrupted during surgery with a transannular patch (TAP) , PR is almost always inevitable

• Some centers are advocating valve sparing repair with patch augmentation of main PA but not across the pulmonary annulus; creation of a PV monocusp using PTFE

• Y incision bec main PA hypoplastic • Augment with a patch

ECHO assessment of rTOF - Residual Lesions - Sequlae of TOF repair - PR severity - RV function

Residual Lesions

• Right Ventricular Outflow Tract Obstruction / Residual Infundibular Stenosis

• Pulmonary Valvular Stenosis

• Residual Ventricular Septal Defect

Echo assessment: Sequelae of TOF Repair

• Pulmonary regurgitation

• RVOT aneurysm

• RV dilatation and dysfunction

• LV dysfunction

• Tricuspid regurgitation

• Pulmonary artery stenosis • Aortopathy – aortic root dilatation and aortic regurgitation • Pulmonary hypertension (late repair of pink TOF)

Residual VSD and severe PR

Challenging: • Residual VSD shunt, need to scan at all planes and windows

• Standard SAX view, no residual VSD seen

• Modified low SAX view from LSE showed residual VSD with left to right shunting on colour Doppler • For VSD patch, residual shunt usually present at either end of the patch

RVOT Aneurysm

• RVOT aneurysm can occur after extensive infundibular resection with or without patching

• Contribute to RV dysfunction

• Initiation of ventricular arrhythmia

Tricuspid regurgitation

•One mechanism for TR involves disruption of the integrity of the tricuspid septal-anterior commissure by the VSD patch, resulting in TR jet originating at the junction between the VSD patch and the septal TV attachment

•More commonly TR is due to annular dilatation secondary to RV enlargement and basal-lateral displacement of the free wall papillary muscles

LV dysfunction

Ghia et al, JACC 2002

Normal/mild LV dysfunction

Moderate / severe LV dysfunction

Aorta in TOF: • Don’t forget the aorta in TOF, it can dilate over time • Not only the aortic root but try to see as much of the ascending aorta as possible

• Patient post TOF repair with a dilated aortic root and also dilated ascending aorta with max dilatation at the mid region

ECHO assessment of Pulmonary Regurgitation - PR Severity

How to assess PR on echo?

• Haemodynamics of PR

• Understanding the etiology of the PR

• PR jet width

• PR index (PRi)

• PR pressure half-time

• Diastolic reversal in branch PA

• RV dilatation

Haemodynamics of PR

RIGHT HEART HAEMODYNAMICS IN SEVERE PR • Premature TV closure closure (PTC) occurs in mid diastole when RVDP > RAP • Premature PV opening (PPVO) occurs when RVEDP > PADP

PR

TR jet

SYSTOLE

DIASTOLE

Etiology of the PR

• Reading the surgical op notes is crucial

• Nearly all TOF patients with trans-annular patch will have some degree of PR

• Assess for suprapulmonary and branch PA stenosis which may worsen the degree of PR

• Serial follow up of TOF patients with PR – expect the expected

– look out for the unexpected

• TOF patient with pulmonary homograft replacement for severe PR 3 years ago

- presented with weight loss and fever - not seen dentist for 3 years

• Look at all echo windows

• Zoom, playback

• Correlate with clinical data

PR, PR, PR : • In adult post repair TOF patients, PR …..PR….PR • PR often underestimated, use other measurements besides color Doppler

• Severity of PR cannot be assessed in isolation. Invariably, significant PR will result in RV dilatation and dysfunction • Must be a reason for RV dilatation if there is no ASD or TR

DOES

Pulmonary Regurgitation Matter?

Survival Post TOF Repair

• Early repair by experienced surgeons preferably without RVOT patch (Nollert JACC 1997)

• Look out for late mortality after 25 years (Nollert JACC 1997)

• Sudden death and cardiac failure are the most common causes of late mortality (Nollert JACC 1997; Gatzoulis Lancet 2000)

• Right ventricular dysfunction secondary to pulmonary

regurgitation is the most important underlying mechanism (Gatzoulis Lancet 2000)

49%

27%

3% 6%

15%

SCD CHF Re-operation CAD Non-Cardiac

793 adult pts (1985-95, repair age 8.2 ± 8,time from repair 21.1 ± 8.7 years); 33 pts died (4.2% mortality)

Late Death in Repaired Tetralogy

• In 15/16, sudden cardiac death (SCD) was the first arrhythmic presentation

• Arrhythmias => 33 patients non-sustained VT, 16 SCD, 29 new onset Aflutter/AF

• Association between arrhythmias and Pulmonary Regurgitation

Gatzoulis Lancet 2000

N=16

0

20

40

60

80

100

VT

SD

AF

Arrhythmia-free

RVSP TR PR (>60mmHg) (> moderate) (> moderate)

% p

atie

nts

Gatzoulis Lancet 2000

How important is Pulmonary Regurgitation?

Pulmonary Regurgitation Fraction (%) 60 50 40 30 20 10 0 -10

% p

eakV

O2 p

redi

cted

1.4

1.2

1.0

.8

.6

.4

.2

r=-0.4 p<0.01

Davlouros et al EHJ 2002

Does Pulmonary Regurgitation matter? Exercise intolerance

Pulmonary Regurgitation in Pregnancy

Khairy et al., Circulation 2006

Impaired RV function +/- pulmonary regurgitation: Independent predictor of adverse maternal events during pregnancy

How to best assess

PR severity?

• Mild-to-moderate PR seen on echo is common and does not require further follow-up or intervention

• Significant PR in patients is uncommon and usually follows after childhood surgery for TOF or other congenital lesions

• The pulmonic valve is rarely involved by IE in the normal population or RHD but is susceptible to carcinoid accretion and results in varying degrees of stenosis and regurgitation.

• Grading of PR severity remains difficult since standards for quantification of PR are less robust than for AR • The vena contracta is probably the most accurate approach • In all cases, the experts recommend corroborating the results of these methods with the other available parameters.

ECHOCARDIOGRAPHY, Volume 25, September 2008

But is vena contracta really that useful? Shapes of vena contracta on 3D in 18 randomly selected patients with PR – complex shapes, cannot have any geometrical asssumptions on the VC

• Echo is the first-line diagnostic

technique, providing the assessment of residual RVOTO and PR, residual VSD, RV

• and LV size and function

• Significant PR is almost always encountered following a transannular patch repair.

• Severe chronic PR, eventually leads to symptomatic RV dilation and dysfunction

• The severity of PR and its • deleterious long-term effects are

augmented by co-existing • distal PA stenoses or PAH (the

latter is uncommon)

ECHO PARAMETERS for ASSESSING PULMONARY REGURGITATION - PR JET WIDTH

PR JET WIDTH • Broad, laminar, retrograde diastolic flow on colour Doppler

originating at PV level

• Jet width > 0.98 cm had 90% accuracy of discriminating between those with MRI PRF of more than 24.5%

(Li et al, Am Heart J 2004; 147:165-72)

PR JET WIDTH

Severe or free PR as jet width is as broad as the PV annulus

• Scroll slowly, stop the frame and measure the max jet width (usually in early diastole) wrt to the PV annulus at the same level • The PR jet width / annulus ratio cutoff point for determination of severe PR (>40% PRF) was 0.7 (MD Puchalski et al , Congenit Heart Disease. 2008;3:168–175)

ECHO PARAMETERS for ASSESSING PULMONARY REGURGITATION - PR INDEX (PRi)

Pulmonary Regurgitation Index (PRi)

• Severe PR has shorter duration; not valid for stiff RV (Li et al, Am Heart J 2004; 147:165-72)

PR index (PRi) = PR duration / time in Diastole

A PRi 0.77 had 100% sensitivity and 84.6% specificity for identifying patients with pulmonary regurgitant fraction 24.5%, with a predictive accuracy of 95% (Wei Li et al, Am Heart J 2004;147:165–72.)

PRi = 314 / 529 = 0.60

ECHO PARAMETERS for ASSESSING PULMONARY REGURGITATION - PR Pressure Half-time

Pulmonary Regurgitation Pressure Half-Time

• PR pressure half-time < 100ms

(76% sensitivity and 94% specificity for PRF >20% on MRI, identify PR of moderate to severe degree) in repaired TOF patients

(Silversides et al, JASE 2003; 16:1057-62)

PR Pressure Half-Time

Pulmonary pressure half-time < 100 milliseconds was found to be a good indicator of hemodynamically significant regurgitation (Silversides et al, J Am Soc Echocardiogr 2003;16:1057-62.)

• Short Deceleration Time in the PR spectral Doppler signal is usually indicative of severe PR (principle behind the P1/2t of <100 ms)

• This will leave long period of ‘‘no flow’’ as PR duration is shortened (Hence PR duration/ duration of diastole – principle behind PRi of <0.77)

• Antegrade flow in the latter part of diastole can occur with atrial contraction (Premature PV opening as RV and PA diastolic pressure equilibrates)

Caveat: PR P½t and PRi cannot be used when RV is stiff as the RVEDP would already be elevated, affecting the equilibration of RV and PA pressures

ECHO PARAMETERS for ASSESSING PULMONARY REGURGITATION - Diastolic Flow Reversal in Branch PA

Diastolic Flow Reversal in Branch PA

Diastolic reversal in branch PA

The best univariate predictor of severe PR was branch pulmonary artery diastolic flow reversal (Renella et al, Journal of the American Society of Echocardiography 2010;23:880-6)

PW Doppler at the level of proximal RPA • Diastolic flow reversal present in branch PA

J Am Soc Echocardiogr 2014;27:111-41

• Mild PR : persistent flow gradient at end-diastole

• Mod PR: equilibration of pressures between the MPA and RV only at end- diastole • Severe PR: Early

diastolic pressure equilibration

Pattern of diastolic flow reversal at LPA seen with varying degree of PR severity

ECHO PARAMETERS for ASSESSING PULMONARY REGURGITATION - RIGHT VENTRICLE DILATATION

Pathophysiology RV dilatation in Chronic PR

• RV adaptations depends on degree and duration of PR, properties of RV and PAs, presence of branch PA stenosis

• PR => Increased RVEDV =>RVESV

• Progressive RV dilatation =>TR=>RV dilates even more + RA dilatation

• RV dilatation and stretch => slow interventricular conduction, substrate for VT, atrial flutter, etc.

• Serial increase in QRS duration reflect RV dilatation

• Restrictive and stiff RV =>conduit for forward pulmonary flow during atrial contraction in late diastole

• Restrictive RV can limit PR and degree of RV dilatation in short term

Assessment of RV function is

an integral part of the echo examination in adult TOF patients with severe PR

ESC Guidelines: Recommendation for PVR ESC 2010 Guidelines on

management of GUCH : • Pulmonary valve replacement (PVRep) and/or

relief of RVOTO can be performed with low mortality (<1%) in patients without heart failure and/or advanced ventricular dysfunction

• Optimal timing remains challenging. Longitudinal data are more important than single measurements to assist timing for re-intervention. Normalization of RV size after re-intervention becomes unlikely as soon as the end-diastolic volume index exceeds 160 mL/m. Distal PA stenosis must be addressed, either at the time of surgery (including intra-operative stenting) or with a percutaneous approach

• Tissue PVRep seems to have a mean life span of 10–15 years. There is little experience with mechanical valves in this setting and there is concern about adequate anticoagulation

MRI assessment of post op TOF patients

CMR for post op TOF patients • Important complementary imaging to echo

• Gold standard for RV assessment in terms of RV volume

and function. LGE for fibrosis

• Quantitative assessment of PR – PR fraction

• Assess main PA and branch PAs – residual branch PA stenosis (site and size). MAPCAs

• Quantify residual shunt

• Size and extent of aortic dilatation

Methods: Global RV function

CoV (%) Right Ventricle Left Ventricle InterScan Intraobserver Interoberver InterScan Intraobserver Interoberver

Variable Observer 1 Observer 2 Obs1 vs. Obs 2 Observer 1 Observer 2 Obs1 vs Obs 2

EDV 4.91 2.89 5.65 4.80 4.73 7.86 MASS 4.49 5.27 7.91 3.12 5.86 4.44 ESV 3.69 4.15 6.82 6.27 5.77 11.31 SV 5.53 6.22 4.68 4.99 5.46 3.46 EF 1.46 3.10 4.92 2.07 2.37 2.69

Babu-Narayan, Bouzas et al, JCMR 2005; 7: S-153 – S-153

-400

-300

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-100

0

100

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500

600

0 200 400 600 800 1000 1200 1400

trigger delay (ms)

flo

w v

olu

me

(ml/

s)

systolic forward flow

diastolic reversal

late diastolic forward

flow

systole diastole late diastole

Methods: Measurement of PRF

MRI Gadolinium enhancement Myocardial fibrosis in repaired TET

Babu-Narayan et al Circulation 2006

Babu-Narayan et al Circulation 2006

MRI Gadolinium enhancement Myocardial fibrosis in repaired TOF

MDCT assessment of post op TOF patients

MDCT for post op TOF patients

• Usually not the first or second line investigations because of radiation dose. CMR preferred over MDCT

• Useful for assessment of coronary arteries in post op adult TOF patients – congenital coronary anomalies (origin, course) or CAD in older TOF

• Assessment pre and post branch PA stenting

• Aortic dilatation – Aortic dissection

JASE 2014:27, pg131-132

• 3D reconstructed CT showing coronary artery course in a post repair TOF patient (above)

• Widely patent stents in the main PA and

branch PAs (right)

Summary • In post repaired adult TOF patients, we need to know exactly what had

been done during surgical repair to anticipate any residual lesions and the expected sequelae from the surgery, commonest sequlae encountered is PR

• Several echo methods are available to assess PR severity. Know the limitations of each method

• Severe pulmonary regurgitation is not a benign lesion or isolated lesion, look at its effect on RV and the other right sided valve – tricuspid valve

• The degree of RV dilatation and dysfunction is an indirect assessment of the sequlae of chronic significant pulmonary regurgitation

• The gold standard of RV assessment is with CMR – RVEDVi, RVESVi, RVEF, PR fraction and LGE

• The main aim of echo and CMR imaging in these post op adult TOF patients with PR – to guide the timing for PVR