ABSENT SINGLE PULMONARY CUSP CAUSING ISOLATED PULMONARY VALVAR
REGURGITATION
INTRODUCTION:
Isolated pulmonary valve regurgitation (IPVR) is very rare (0.8% of
CHD) [1]. We present an even rarer case of IPVR caused by the
absence of a single pulmonary cusp.
Guidelines are not established regarding indications and timing of valve
replacement for congenital IPVR. With review of literature, we propose a
management outline for this condition.
CASE REPORT:
15 year old male, diagnosed with a congenital dysplastic pulmonary valve
(PV), presented with palpitation and breathlessness (NYHA class II) for
one year. He had sinus tachycardia and grade 4/6 early diastolic murmur
at the left 2nd intercostal space. Electrocardiogram
showed sinus rhythm, right axis deviation with complete right bundle
branch block. Chest X-ray showed increased cardiothoracic ratio with
dilated main pulmonary artery (MPA). Transthoracic echocardiography
(TTE) showed paradoxical septal movement; dilated PV annulus (31mm), MPA
(57 mm) and branch pulmonary artery (PA) - right (24mm) and left
(26mm),severe PR.The patient underwent cardiac computed tomogram (CT)
and magnetic resonance imaging (MRI) to delineate Pulmonary artery
anatomy and right ventricular (RV) dimensions. Imaging revealed severe
PR with absence of single PV leaflet and dysplastic but normal sized
remaining 2 leaflets (FIG 1 ). RV ejection fraction (RVEF) was 48% and
RV end diastolic volume index (RVEDI) was 187ml/m2.
There was no bronchial compression from dilated PAs.
At surgery, MPA was dilated with dilated branch PAs. Posterior and right
pulmonary cusps were dysplastic and left cusp was absent. (Figure
2).Number 23 stented bioprosthetic valve (LivaNovaCECrown PRT) was used for PV replacement. Postoperative period was
uneventful.
DISCUSSION:
Among the causes for congenital IPVR, idiopathic dilatation of MPA is
most common (0.6% of CHD) and bicuspid PVs are considered to be the
rarest (0.2% of CHD) [1]. The term bicuspid PV refers to an anatomy
similar to those described in bicuspid aortic valves, wherein the valve
has 2 leaflets that are attached at 2 commisures - Bicommisural[2].
In a semilunar valve with absent single cusp, there are 2 dysplastic or
normal cusps attached at a single commissure and the third cusp is
absent. There are only 3 reported cases with absent single cusp causing
severe PR (table 1) [3,4]. Ours is the fourth.
IPVR is usually well tolerated. Symptoms develop around 4 th decade of
life when PR becomes chronic and RV dysfunction established.
Irrespective of etiology, symptoms are those of right heart failure,
arrhythmias, syncope and sudden cardiac death [1]. While MPA and
branch PA dilatation is a noted pathology, reports of airway compression
by these dilated vessels is scarce. Literature search revealed analysis
of this observation only in a sub groups of infants with prenatal
diagnosis of absent PV syndrome; those with associated Tetralogy of
Fallot (TOF) and with intact ventricular septum (which would later
become IPVR) [5,6]. The observations from these rare reports (2/15
cases) are that presence of a ductus arteriosus to the MPA decompresses
the branch PA and thereby reduce chances of airway compression. Long
term outcomes of this cohort is unavailable.
Due to rarity of cases, literature is devoid of guidelines for operating
on cases with congenital IPVR [7]. Azam Ansari, has reported 69
cases since 1955 and has compared the etiology and management of this
rare lesion [1]. In the current era, the proposed investigations
such as fluoroscopy, cardiac catheterization and indicator dilution
studies would be replaced by echocardiography, CT scan and MRI. With
newer investigations, the indications of surgery also change. 2D TTE
with colour flow Doppler would be the recommended first line
investigation for establishing diagnosis and severity of the PR [8].
Manivarmane et al recommended routine use of biplane and 3D imaging in
both TTE and transoesophageal echocardiography to delineate PV anatomy
in IPVR [8]. The use of 3D transesophageal echocardiography is
currently limited to older patients because of technical limitations.
Cardiac MRI would be essential in planning management. Since volumetric
data of IPVR is scarce, planning treatment protocols require
extrapolation from the published literature on corrected Tetralogy of
Fallot. Parameters considered are Effective Regurgitant Orifice Area,
Regurgitant volumes, RVEF, RVEDI and RV end systolic volume index
(RVESI) [9].
Therrien et al reported that PV replacement fails to normalize RV
dimensions when performed for RVEDI ≥170ml/m2 and
RVESI
≥ 85 ml/m2 in corrected Tetralogy of Fallot. The
average duration between surgeries in this study was 29+/- 9 years. The
indications of surgery were the presence of RV dilation and hypokinesia
(100%), severe PR (94%), exertional dyspnea (70%), and recurrent or
sustained arrhythmias (59%). Multi planar MRI imaging was considered
better than echocardiography and radionucleotide imaging for
reproducible quantitative analysis of RV volumes and function [10].
Extrapolating from the findings of the above mentioned study [10],
we propose that earlier intervention at RVEDI of >150
ml/m2 should offer a safer margin for RV normalization
after PV replacement.
In an anatomy as in this case, when the valve is inherently regurgitant,
the timing of PV replacement, should be with early signs of RV
dilatation. Other considerations would be development of sustained
atrial or ventricular arrhythmias, development of tricuspid
regurgitation, or additional lesions needing bypass surgery. In late
presenters, moderate to severe RV dysfunction is an indication for valve
replacement. (Proposed management outline Fig 3).
CONCLUSION:
Congenital IPVR due an absent single pulmonary cusp is a very rare
entity. The timing of pulmonary valve replacement in this setting should
be at the onset of RV dilatation to avoid progressive ventricular
dysfunction.
INFORMED CONSENT: Obtained (oral consent)
As per the institution‘s policy, Institute‘s ethical board issued a
waiver for this case report.
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Reson 13, 9 (2011)
- Optimal Timing for Pulmonary Valve Replacement in Adults After
Tetralogy of Fallot Repair Judith Therrien, MD, Yves Provost, MD,
Naeem Merchant, MD, William Williams, MD, Jack Colman, MD, and Gary
Webb, MD (Am J Cardiol 2005;95:779–782)
Figure Legends
Figure 1: A – CT scan image of the cross section of right ventricular
outflow tract at the Pulmonary Valve level with absent left leaflet.
B- 3D Transesophageal image showing absent left pulmonary valve leaflet
(black arrow)
Figure 2: A- Surgical image of Pulmonary Valve – White arrows showing
the dysplastic posterior and right pulmonary leaflets. Black arrow
showing the absent left leaflet.
B - Number 23 stented bioprosthetic valve (LivaNovaCECrown PRT) in position in the pulmonary artery.
Figure 3: Flow Chart with proposed management outline for IPVR