Successful hybrid management of hypertensive patent ductus arteriosus with unilateral absence of the right pulmonary artery – A case report

ABSTRACT

Unilateral absence of pulmonary artery (UAPA) can be either isolated or associated with other congenital cardiac defects. It is a rare congenital lesion with a diverse clinical presentation. We present a case of absent right pulmonary artery and large patent ductus arteriosus (PDA) with severe unilateral pulmonary hypertension. We describe our strategy of staged ductus arteriosus closure in this patient and successful outcome on long term follow up.

INTRODUCTION

Congenital unilateral absence of the branch pulmonary artery is a rare condition with an incidence of 0.39% of all congenital heart defects.[1] It can be associated with other congenital heart defects or can be isolated. There is an increased risk of the development of pulmonary arterial hypertension in early childhood, especially if there are other left-to-right shunts. We report a case of a large patent ductus and absent right pulmonary artery first time diagnosed at 5 years of age and describe staged closure of the ductus.

CASE REPORT

A 5-year-old girl presented with poor growth, breathlessness on exertion, and recurrent lower respiratory tract infection. Clinical examination revealed a systolic murmur in the left infraclavicular area with a loud second heart sound. The echocardiogram showed a large patent ductus arteriosus (PDA) with a low-velocity left-to-right flow and dilatation of the cardiac chambers. The left pulmonary artery (LPA) was dilated; however, the right pulmonary artery (RPA) could not be visualized.

Chest X-ray showed plethoric left lung and relative oligemia in the right lung with a prominent main pulmonary artery (MPA) segment [Figure 1]. Cardiac computed tomography–pulmonary angiogram showed a 5 mm collateral from the ascending aorta to the right lung and multiple small collaterals supplying the right lung.

Figure 1.

Chest X-ray showing hypervascularity in the left lung and oligemic right lung

Cardiac catheterization was planned to obtain invasive pulmonary pressures and ascertain operability. The procedure was performed under general anesthesia with endotracheal intubation. During cardiac catheterization, an angiogram in the MPA showed absent RPA, the MPA continued as LPA, and the presence of a large tubular PDA [Figure 2a and b].

Figure 2.

(a) Absent right pulmonary artery and main pulmonary artery continuing as the left pulmonary artery in the right ventricular outflow tract angiogram, (b) lateral angiogram showing tubular patent ductus arteriosus (PDA), (c) PDA occluded with (12 mm × 30 mm) Tyshak II Balloon

During cardiac catheterization, after a baseline hemodynamic study before and after 100% oxygen inhalation, the duct was trial occluded by a 12 mm × 30 mm Tyshak II Balloon – (NuMed, Hopkintown, NY) placed across the duct from the right femoral arterial access. A 5-F side hole multipurpose catheter (Cook, USA) was placed in the LPA through the left femoral arterial access to check the pulmonary artery (PA) pressure after trial occlusion of the duct for 15 min [Figure 2c]. The mean PA pressure reduced from 62 to 31 mmHg with no change in the simultaneous aortic pressures [Table 1]. The baseline pulmonary-to-systemic flow (Qp:Qs) ratio was 1.02:1. The indexed pulmonary vascular resistance index (PVRI) came down to 7.1 WU.m² from its original of 10.2 WU.m² with oxygen [Table 1]. As it showed a drop in the PA systolic pressure >20% from the baseline after trial occlusion but failed to show clear-cut reversibility with oxygen, the decision was taken to partially ligate the duct to reduce the pulmonary flow.

Table 1.

The pressure data and saturation before and after oximetry and balloon occlusion of patent ductus arteriosus

Oximetry data	Without oxygen (room air)	With oxygen	Postballoon occlusion
AAO pressure (saturation %)	81/57/65 (98.4)	86/63/74 (98.9)	83/45/59
DTA pressure (saturation %)	86/61/69 (91.8)	89/64/76 (99.3)	88/46/61
PA (LPA) pressure (saturation %)	79/53/62 (83.6)	71/43/59 (92.2)	50/22/31
MVO2 (saturation %)	75.2	78.8	-
Qp L/min	5.59	8.12	-
Qs L/min	5.48	4.52	-
Qp/Qs	1.02:1	1.8:1	-
PVRI (WU.m2)	10.2	7.1	-
SVRI (WU.m2)	11.2	17.4	-
PVRI/SVRI	0.91	0.41	-

Expand all abbreviations in the table. PA: Pulmonary artery, LPA: Left pulmonary artery, PVRI: Pulmonary vascular resistance index, PDA: Patent ductus arteriosus, SVRI: Systemic vascular resistance index, AAO: Ascending aorta, Mvo₂: Mixed venous oxygen saturation, DTA: Descending thoracic aorta, Qp: pulmonary flow, Qs: systemic flow

The duct was partially ligated over a metallic tube leaving a 2 mm shunt as the right ventricular pop-off for any post procedure rise in pulmonary artery pressure. In the immediate postoperative period, the echocardiogram showed a left-to-right gradient of 16/3 mmHg across the ductus. The patient was discharged on oral sildenafil.

Three years into follow-up, a repeat echocardiogram showed persistent 2 mm residual PDA with a left-to-right pressure gradient of 90/30 mmHg and mild left heart dilatation [Figure 3a]. The decision to complete ductal closure was made in view of normal pulmonary pressures as assessed from an echocardiogram.

Figure 3.

(a) Restricted residual patent ductus arteriosus (PDA) in ductal view (transthoracic echocardiogram), (b) angiogram after PDA device deployment, (c) arch angiogram after PDA device deployment (before release), showing prominent collateral supplying the right lung

The procedure of ductal closure was performed under local anesthesia and intravenous sedation. Bilateral femoral venous and right femoral arterial accesses were obtained. The baseline direct PA pressure was found to be 40/13/20 mmHg. The duct was closed with a 5 mm × 4 mm Amplatzer duct occluder device (ADO1, Abbott Inc.) [Figure 3b]. After device closure, the PA pressure was 34/10/18 mmHg, measured by an end-hole multipurpose MPA1 (Cook, USA) catheter placed in the LPA, through left femoral venous access.

An arch angiogram was done after PDA device deployment (before device release), and it showed no residual ductal flow and prominent collateral supplying the right lung [Figure 3c]. There was a slight rise in the PA pressure on the postprocedure echocardiogram. The PA systolic pressure as assessed from tricuspid regurgitation jet velocity was 45 mmHg; hence, the patient was put on oral sildenafil at 2 mg/kg in three divided doses.

Further follow-up at 3 months showed normalization of the PA pressures, and the sildenafil was stopped. The patient is currently well with normal cardiac chamber size and function and normal PA pressures as assessed on echocardiogram at 6-month follow-up.

DISCUSSION

Unilateral absence of the pulmonary artery (UAPA) is a rare defect with an incidence of 0.39% of all congenital heart defects. This defect was first reported by Frentzel in 1868.[2] In most cases, UAPA is associated with other congenital heart defects such as tetralogy of Fallot, septal defects, PDA, and truncus arteriosus. UAPA is often incidentally diagnosed during the evaluation of the associated lesions. In up to 30% of cases, UAPA occurs without any other associated cardiovascular anomalies and is called isolated UAPA, going undiagnosed for a long time due to lack of symptoms.[3,4]

In the presence of a large PDA, the PA pressures may become irreversible as early as 2 years.[5] This happens due to the continuous transmission of high-pressure flow from the aorta to the pulmonary circuit throughout the cardiac cycle. There may be a small subgroup of patients in whom, despite elevated total pulmonary vascular resistance, a reversible component may be found, which may be assessed by trial occlusion of the duct by a balloon or device.

Test occlusion of the PDA to assess safety for transcatheter PDA closure can be done by two methods. It can either be done by balloon occlusion or using the anticipated device itself. The three important parameters after test occlusion of the PDA to assess safety are as follows: (a) 20% drop in the baseline systolic PA pressures or at least no increase in systolic pulmonary artery pressure (PAP), (b) no drop in the systemic pressure. This suggests that the PDA was not required to provide cardiac output, and (c) no drop in oxygen saturation or clinical signs of pulmonary hypertensive crisis.[6]

A posttrial occlusion systolic pulmonary: systemic pressure ratio >0.5 may be a useful hemodynamic parameter for identifying patients with borderline pulmonary arterial hypertension (PAH), who have a high risk of residual PAH after PDA closure. Muscular ventricular septal defect device and Amplatzer duct occluder device, Equalizer Balloon (Boston Scientific, MA, USA),[7,8] have been used to trial occlude the PDA by various authors. Simultaneous aorta and PA pressure were taken by saline-filled catheters, and if a patient developed symptoms (chest pain and shortness of breath) or hypotension where the systolic aortic pressure fell below the PA systolic pressure or the pulmonary artery systolic pressure did not fall below the systolic blood pressure, then trial occlusion process was aborted.[7]

A small subset of patients with severe PAH and borderline hemodynamics may not benefit from PDA closure and may eventually develop right heart failure from progressive pulmonary vascular disease.[8] Thus, identifying this small percentage of reversible patients by meticulous vasodilator testing and test occlusion of the duct, followed by partial closure of the PDA, either surgically by partial ligation of the PDA (ligating the PDA stump over a metallic tube so that the residual PDA acts as pop-off) or by creating a fenestration in the PDA device is a promising new strategy.[8] In this subgroup, the pulmonary vascular change is still in the early stage of muscular hypertrophy. However, the pulmonary vascular change, even when reversible, takes longer to normalize after the closure of shunt lesions.[9]

After eliminating the large shunt, aggressive pulmonary vasodilator therapy can be initiated for the residual PAH if present. Fortunately enough, our patient fell into this rare subgroup and, thus, benefitted from shunt closure.

For obvious reasons, patients with coexisting large ductus and single PA should be intervened at the earliest to protect the only functioning lung. Unfortunately, our patient was diagnosed with having a large ductus for the first time at the age of 5 years, by which time her right lung pressures were already very high. Even though the PVRI after a 100% oxygen administration was in the gray zone for reversibility, after trial occlusion of the duct, the drop in the PA pressure was encouraging. Our strategy of partial duct ligation and staged complete closure of the ductus was well tolerated by the patient and led to the normalization of the PA pressure on follow-up.

CONCLUSION

Individuals with unilateral absent branch pulmonary artery are at an increased risk for the development of pulmonary hypertension to the normally connected lung. This risk increases sharply when there is an associated large left-to-right shunt lesion; hence, such association should be addressed early. Our approach of staged closure of a large ductus, in an attempt to preserve the only functioning lung, was rewarded by complete normalization of the pulmonary pressures.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.