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How Small is Small RV in PA/IVS Dr. Mashail Alobaidan,MD Consultant Pediatric Cardiology Interventionalist, PSCC SHA 24th & 10th GHA


17 Days baby boy referred to PSCC due to cyanosis on PG and ventilatory support


9 days baby boy referred to PSCC with cyanosis commenced on PG and ventilatory support


23 days old has cyanosis after birth commenced on PG referred to PSCC


PA/IVS

PA with Hypoplastic RV &TV

PA dysplastic TV, TR& normal sized RV &TV

Incomplete normal TV

Congenitally unguarded TV


PA/IVS Morphology  All morphologic abnormalities occurs proximal to Rt. V-A junction  PV–may vary from long segment muscular atresia to fused trileaflet with well developed commissures and sinuses.  RV is abnormally hypertrophied and Hypoplastic  RV morphology may be unipartite, bipartite or tripartite  Size of the RV correlates with TV annulus size.  Less commonly RV is thinned and dilated– Ebstien’s anomaly.


Autopsy specimens from neonates with PA /IVS showing right ventricles with (A) inlet , trabecular and infundibular portions to the cavity, (B) obliteration of the trabecular portion, and (C) obliteration of both infundibular and trabecular portions.


Spectrum of pathology PA/IVS. RV angiograms showing;( A) tripartite RV with membranous atresia ; (B) bipartite RV with membranous atresia, with some RV-C fistulae; (C) tiny unipartite RV with muscular atresia and RV-C fistulae with retrograde filling of the aorta.


Treatment Algorithm  The choice of treatment algorithm depends on: * The estimated adequacy of the RV to cope with systemic venous return, and its potential for growth * The size of TV, and * The status of the coronary arteries.  If adequate RH structures, achievement of patent RVOT ( RVD) in the newborn period  If inadequate RH anatomy or coronary artery anomalies…… staged procedures leading to UVH


Primary transcatheter valvotomy strategy permits (as does surgery) forward blood flow early in life through the RV outflow tract, which may encourage PA growth and, with acquired PR , potential RV growth.


ďƒ˜Are there an appropriate anatomic criteria to patient selection, for a particular treatment algorithm. ďƒ˜Is the initial size of the RV significant in defining the treatment algorithm, particularly as it was difficult to estimate its size or volume.

How Can We Assess RV ?


ďƒ˜ There is debate as to the best method >> To assess RV size and its adequacy for a biventricular repair >> To monitor growth of the chamber and valve.


 Studies in late

1980s :

 Various measures of RV and TV might predict which patients with PA-IVS had RVs that were capable of growth to normal size and thus which patients would benefit from early RV decompression.  Patients with significant RV and TV hypoplasia did poorly  and tiny RH structures were incapable of normal growth with preserved long-term RV function


• Hanséus et al 1991 showed that newborns with a very hypoplastic RV almost always have normalized values for RV size after 52 months (range 18 to 87 months). • >>>> The best chamber growth was achieved in patients who underwent RV outflow reconstruction in the neonatal period.


Outcome of critically ill neonate with PA/IVS Frank Henley et al JACC 1993

The right ventricular cavity size was estimated based on information obtained by echocardiography or angiocardiography, or both, and at operation. Cavity size was graded as follows by scoring :  0 = normal (for age),  -5 = extreme hypoplasia and  - 1 to -4 = intermediate degrees of hypoplasia.


T M Giglia, K J Jenkins, A Matitiau, V S Mandell, S P Sanders, J E Mayer, Jr and J E Lock Circulation. 1993;88:2248-2256  The opening of RVOT in the neonatal period depends on the

potential of the RH structures to grow and

develop which is predicted by initial RH structure measurement.  The RVDV was measured at end diastole in the subxiphoid long- and short-axis planes and estimated using a Simpson's rule algorithm and was indexed for body surface area.  The maximum TV annulus …..4-chamber view.


 No significant association between indexed RVV or TVD and survival.  Significant association between indexed RVV and TVD and the presence of RVDCC, contributing to mortality.  Most patients with small RHS have evidence for excellent RV function at a mean follow-up of 5.0 years  Indexed RVV for the patients ranged from 1.0 to 22.1 mL/m2, and TVD ranged from 4.3 to 20.0 mm. * estimated normal values for RV volumes range from 30 to 50 mL/m2; normal newborn TV dimensions range from 9 to 17 mm.


Therefore the CA anatomy and not RV or TV hypoplasia predicts which patients with PAIVS will do well after early RVD.


 Cheatham 1997 suggested that, as long as there was  a tripartite RV and  a well formed infundibulum,  a tricuspid valve annulus 11 mm, and  membranous atretic PV annulus 7 mm >>>>> transcatheter therapy should be performed.  However, no supportive data for these recommendations were given


Right ventricular angiogram in the lateral projection showing a well-developed trabecular component, patent infundibulum and atretic pulmonary valve (arrow). Moderate tricuspid regurgitation.


• Ovaert et al 1998 & Minich 2000 noted an increased TV diameter over time, with a positive relationship toward higher tricuspid/mitral valve diameter ratios >0.5 ďƒ˜ Normal TV growth might not be necessary for an RV competent circulation, to maintain the pulmonary circulation, and the initial size of the tricuspid valve might be only a weak indicator of outcome.


How to assess RV Tilman Humpl, Freedom, William G. and Lee N. Benson Circulation 2003;108:826-832

 The diameter of the TV in early diastole (from inner edge to inner edge),  The RV length (TV annulus to apex at VED), and  The RV area at end diastole with the maximal area bordered by RV endocardium (all measurements in the apical 4-chamber view).

 The tricuspid valve Z score, RV length Z score, and RV area Z score.


Nomograms of TV (A) and RV (B). This allows estimation of the TV and RV Z scores from knowledge of the TV or RV dimension and body surface area.


Z Score of RV area


• There was significantly differences of Z value for the TV in patients who underwent a further intervention versus the Z value for those with no further intervention. • There was an enlargement of the TV and RV length, RV area and the dimensions paralleled normal ones. • It is difficult to predict, at the time of presentation, whether the RV will have the potential for accommodating systemic blood return. • A “normal”-sized RH is not required to maintain at rest a normal pulmonary blood flow with an acceptable right atrial pressure.


Conclusion Only those patients with >> very diminutive right-sided structures, a >> severely attenuated infundibulum, or >> coronary artery anomalies were not considered as candidates for a catheter-based valvotomy.


Yoshimura N. et al.; J Thorac Cardiovasc Surg 2003;126:14171426

 The type of initial procedure has been decided in conformity with the value of calculated RVDI, according to the following equation:

 RV angio were performed in the AP and lateral projections.  RVEDV was calculated using Simpson’s rule and the linear regression equation of Graham and associates. The volume was then expressed as a % of expected normal values using the method of Nakazawa and associates


 TVD was measured from the RV angio. in the enddiastolic phase from the superior to the inferior rim of the annulus. The diameter was expressed as a % of the predicted diameter of the TV derived from the Bull’s modification of the autopsy data by Rowlatt.  The RVOD was measured at the narrowest portion in the lateral projection at the end-diastolic phase


Angiographic Calculations of RVEDV, tricuspid valve diameter (TVD), and diameter of the right ventricular outflow tract (RVOD)

Yoshimura N. et al.; J Thorac Cardiovasc Surg 2003;126:1417-1426


Right ventriculogram of a patient who underwent one and a half ventricular repair. RVEDV, TVD, and RV-TV index were26.6%, 55.7%, and 0.148, respectively.


Interpretation  If RVDI > 0.7, valvotomy was performed .  When RVDI was between 0.35 and 0.7, in addition to valvotomy, ß-blocker was administered.  When RVDI was <0.35, BTS was created simultaneously with the valvotomy.  In cases with muscular atresia or right ventricle– dependent coronary circulation, only a BlalockTaussig shunt was performed for initial palliation.


Interpretation In terms of staged definitive repair, complete biventricular repair will be accomplished in patients with the RV-TV index 0.4.  For patients with the RV-TV index ranging between 0.2 and 0.4, biventricular repair with partial closure of ASD. When the RV-TV index is between 0.1 and 0.2, one and a half ventricular repair seems to be a procedure of choice. For patients with the RV-TV index of lower than 0.1, Fontan-type procedure should be performed.


Anatomic parameters that were measured in the cardiac fourchamber view. Echocardiographic determinants of successful balloon dilation in PA/IVS Drighil1,2*, Mansour Aljufan2,James Mathewson3, and Fadl AlFadly2

Drighil A et al. Eur J Echocardiogr 2010;11:172-175


Tricuspid annulus Z-score, pulmonary annulus Z-score, RV / LV length ratio, RV / LV transverse diameter ratio, and TV / MV annulus diameter ratio were measured.  Rule 1: If RV/LV diameter ratio is >0.76, the probability of successful balloon angioplasty is 92.3%.  Rule 2: If RV/LV diameter ratio is ≤0.76 and RV/LV length ratio ≤0.70, then the probability of an unsuccessful balloon angioplasty is 100%.  Rule 3: If RV/LV diameter ratio is ≤0.76 and RV/LV length ratio is >0.70, then the probability of successful balloon angioplasty is 75%


Patients outcome after balloon dilation depending on RV/LV diameter ratio and RV/LV length ratio.

Drighil A et al. Eur J Echocardiogr 2010;11:172-175


The ratios of RV / LV lengths and diameters provided an immediate comparison between RV and LV size and gave an idea of the degree of RV hypoplasia.

The TV and PV annular Z scores were not as discriminant as the RV/LV length ratio and RV/LV diameter ratio even if they were significantly different between groups where balloon dilation was, and was not, successful. The RV/LV diameter ratio variable is sufficient alone to predict the success of balloon dilation (Rule 1), whereas failure can be successfully predicted from Rule 2.


Independent Predictors of a Biventricular Repair or Need for Further Intervention • The presence of RV sinusoids and • Elevated RV systolic pressure were predictive of failure to achieve a biventricular repair.  The preintervention RV systolic pressure was predictive of the need for further intervention after the initial procedure ** An indirect assessment TV/ MV ratio of 0.5 as a predictor for a successful biventricular repair.


PA/IVS

No RVCCD

Sinusoids

RVCCD

BTS ALONE

TV = 0 to-2 RVOT PROCEDURE

TV = -2 to-3 RVOT PROCEDURE + SHUNT

TV = -3 to-4

TV = ≤-4

One and half

Shunt alone


Conclusion  The best method to assess RV size and its potential growth?

 Agreement that unipartite RV and presence of RVCCD preclude opening of RVOT  Treatment algorithm of PA/IVS lead to several measurements to assess RV and the outcome  TV measurement and Z value is not an independent factor to achieve biventricular circulation  A “normal”-sized RH is not required to maintain at rest a normal pulmonary blood flow with an acceptable right atrial pressure.  The initial size of the tricuspid valve might be only a weak indicator of outcome.  The ratios of RV / LV lengths and diameters provided an immediate comparison between RV and LV size and gave an idea of the degree of RV hypoplasia so to be considered.


Thank you very much Dr. Mashail Alobaidan

SHA24/011004  

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