Patients Characteristics
Surgical reconstruction of the PA in ten patients have been completed with 5 males and 5 females. The median age at the time of operation was 4 months (range, 16 days to 22 months). Median body mass was 5.2kg (range, 3.9 to 10.1 kg). Detailed clinical characteristics were shown in Table 1. Two patients came with TOF had cyanosis, and one patient showed hemoptysis, while all the other children were found with the pre-cardiac murmur or respiratory distress. On chest radiography, it was found that the volume of the lungs on the ipsilateral side was reduced in 6 patients, the mediastinum shifted to the affected side, and the blood vessel markings were reduced. The echocardiogram indicated the main PA with a single branching PA. Eight patients without TOF showed a mean 4.4±0.3 (range, 4.1-4.8m/sec) of peak velocity of tricuspid regurgitation, which indicated the contralateral pulmonary arterial hypertension at the time of UAPA diagnosis. The CT showed absent of intrapericardial PA, the distal PA in the hilum and the blood supply of the affected lung. Nine patients had UAPA affecting the lung contralateral to the aortic arch: right lung/left arch (n=7), left lung/right arch (n=2). Among the 8 patients, a patent ductus (n=1) or a small stump (n=7) was observed at the base of the brachiocephalic artery, which indicated the ductal origin of the abnormal PA. One had blood supply of affected lung from minor collaterals, and the other one’s right lung arterioles have connection with an abnormal vascular cluster from right internal thoracic artery, visualized by cardiac catheterize angiography. [Patient No.5, Figure 1]. The isolated distal PA in the hilum of these patients was hypoplastic (median diameter, 3.1mm; range, 1.6-5mm; Z value, -3.66±1.86; range <-6.7 to -1.75). For the quantitative assessment of two TOF patients’ contralateral pulmonary artery, the Nakata index (NI) (mm2/m2), McGoon ratio were calculated according to previously published equations.[10] Values of NI (mm2/m2) and McGoon ratio in No.4 and No.10 patients were 205.9 ,0.62 and 397.7 ,1.69 respectively. Delay in diagnosis was infrequent.
Table 1. Clinical information for patients with unilateral absence of a pulmonary artery treated with revascularization of the pulmonary artery
No.
|
Sex
|
Age at operation
|
Diagnosis(arch sidedness)
|
Clinical presentation
|
Blood supply of affected lung
|
Diameter of remnant PA (mm)(Z value)
|
Intrapulmonary artery centralization techniques
|
F/U duration
(y)
|
Latest diameter of affected PA (mm)(Z value)
|
Latest blood flow velocities of affected PA(m/s)
|
1
|
M
|
46 d
|
ARPA (left arch)
|
Murmur at birth
|
Brachiocephalic artery
|
3(-3.01)
|
6mm Gore-tex tube
|
5.6
|
5.7(-2.99)
|
1.9
|
2
|
F
|
16 d
|
ARPA, ASD (left arch)
|
Respiratory distress at birth
|
Brachiocephalic artery
|
1.6(-6.74)
|
5mm Gore-tex tube
|
5.4
|
4.5(-4.52)
|
1.6
|
3
|
F
|
6 mo
|
ARPA, PDA (left arch)
|
Murmur at birth
|
Minor aortopulmonary collaterals
|
2.2(-5.44)
|
6mm Gore-tex tube
|
5.2
|
5(-4.27)
|
2.1
|
4
|
M
|
3 mo
|
ALPA, TOF (right arch)
|
Cyanosis
|
Brachiocephalic artery
|
1.9(-5.97)
|
MPA flap angioplasty
|
4.1
|
6.8(-1.4)
|
2.5
|
5
|
F
|
78 d
|
ARPA
(left arch)
|
Respiratory distress at birth
|
Right internal thoracic artery
|
4(-1.88)
|
7mm autologous pericardial roll
|
4
|
4.5(-1.43)
|
1.8
|
6
|
M
|
6 mo
|
ARPA, APW (left arch)
|
Respiratory distress at birth
|
Brachiocephalic artery
|
3.9(-1.75)
|
10mm autologous pericardial roll
|
3
|
6.8(-1.59)
|
1.2
|
7
|
M
|
4 mo
|
ALPA , Obstructive emphysema of right lung
(right arch)
|
Murmur at birth
|
Brachiocephalic artery
|
3.2(-2.82)
|
Direct anastomosis
|
2.7
|
5.6(-1.84)
|
2
|
8
|
F
|
4 mo
|
ARPA , AAOCA (left arch)
|
Respiratory distress at birth
|
Brachiocephalic artery
|
2.6(-4.6)
|
9mm autologous pericardial roll
|
1.3
|
5.4(-2.12)
|
1
|
9
|
M
|
22mo
|
ARPA, PDA, BPD of right lung, ILD
(left arch)
|
Hemoptysis
|
PDA
|
5(-1.83)
|
10mm autologous pericardial roll
|
1.2
|
6.9(-1.35)
|
1.4
|
10
|
F
|
9 mo
|
ALPA, TOF (left arch)
|
Cyanosis
|
Brachiocephalic artery
|
4(-2.59)
|
MPA flap angioplasty
|
0.1
|
4(-1.91)
|
2.2
|
AAOCA Anomalous aortic origin of a coronary artery, ALPA absence of the left pulmonary artery, APW Aortopulmonary window, ARPA absence of the right pulmonary artery, ASD atrial septal defect, BPD bronchopulmonary dysplasia, F female, ILD Interstitial lung Disease, M male, MPA main pulmonary artery, PA pulmonary artery, PDA patent ductus arteriosus, TOF tetralogy of Fallot
Surgical procedures
The operation was performed on the 10 patients immediately after their diagnosis had been made. Isolated UAPA was diagnosed in 6 patients. Coexisting cardiac malformations included atrial septal defect (1 patient), TOF (2 patients), aortopulmonary window (1 patient, type III of Mori [11]). Here we present the surgical procedures of reconstruction of the “neo” right pulmonary artery (RPA) for example, and same surgical techniques were also adopted in rebuilding the “neo” left pulmonary artery. Surgical exploration confirmed UAPA by a median sternotomy incision, and the main pulmonary artery and collateral vessel of the aorta, pulmonary artery and right pulmonary artery of affected lung were completely divided. After the collateral vessel was harvested from the aorta, cardiopulmonary bypass with moderate hypothermia(25-30℃) was established by cannulating the ascending aorta, superior and inferior vena cava. For those patients who were associated with intracardiac malformation, the vena cava was snared, the ascending aorta was clamped, and cardiac arrest was obtained by infusion of antegrade 4°C histidine-tryptophan-ketoglutarate cardioplegia solution through the aortic root before a complete repair was performed.
A well-developed hilar PA could be connected to the posterolateral portion of the distal main PA trunk with a direct tissue-to-tissue anastomosis made with a running 7-0 prolene (Patient No.7). However, we could hardly perform this approach because the hypoplasia hilar PA. Two main approaches are used in intrapulmonary artery centralization. As for the first approach, if a wide distance between hilar RPA and MPA is observed, an autologous pericardial tube created with a running 7-0 prolene or a polytetrafluoroethylene (Gore-Tex, W. L. Gore&Associates, Inc) tube shall be taken to connect hilar RPA and MPA. In the cases herein, the authors directly reconnected the affected PA with a polytetrafluoroethylene tube graft in 3 patients (5mm in 1 patient, 6mm in 2 patients), whereas an autologous pericardial roll was applied in 4 patients (7mm, 9mm in 2 patients, separately, 10mm in 2 patients) (Figure 2). As for the second approach, if the “neo” PA posterior wall can be constructed by directly anastomosis the main PA flap and the hilum vessel, an autologous pericardium patch was used to augment the anterior surface of the “neo” PA from the hilum all the way back to the main PA. (Patient No.4, No.10) During these two approaches, the ascending aorta was not transected. The neo-PA was then placed under the ascending aorta. The mean cardiopulmonary bypass time was 69.7±34.4 min (31–143 min).
Acute outcomes and complications
There were no hospital deaths in those 10 cases. One patient with tetralogy of Fallot and absence of the left pulmonary artery occurred pulmonary hemorrhage after surgery (Patient No.4). The high-frequency oscillatory ventilation was applied for 5 days. A sternal debridement was performed 22 days after the first operation due to the infected median sternotomy wound (Patient No.6). One patient was treated with inhaled iloprost (Ventavis) three days for the control of acute pulmonary hypertension (Patient No.2). For the entire cohort, the median length of intensive care unit stay was 2.5 days (range, 1 to 14 days) and the median duration of hospitalization was 19.5 days (range, 5 to 34 days). To avoid thrombosis inside the “neo” branch PA, daily antithrombotic treatment with aspirin was prescribed in 6 months after the operation.
Follow-up outcomes
No patient died during follow-up session. Median follow-up in this cohort was 3.5 year (range, 1 month to 5.6 years). All patients were asymptomatic and demonstrated class I in the New York Heart Association (NYHA) classification.
The left PA with stenosis at the anastomosis was found in patient No. 4 during serial follow-ups. Nonetheless, recurrent respiratory infections or exercise intolerance were not found in him. Yet, N-terminal pro-brain natriuretic peptide concentration >500 pg/mL and high voltage of the right ventricle on echocardiography were found. We performed transcatheter balloon angioplasty at 41 months after surgery. The diameter of the focal stenosis increased from 1.8mm to 6.8mm, and the mean blood flow velocity decreased to 2.5m/s. The main pulmonary arterial systolic pressure significantly decreased from 53 mmHg before transcatheter balloon angioplasty to 35 mmHg immediately after the intervention. (Figure 3)
Serial echocardiographic findings showed no increase in flow velocity of the patient’s “neo” pulmonary artery. The blood flow velocities at the “neo” pulmonary artery were 1-2.5 m/s (Table. 1). At the latest follow-up, the median size of the affected PA was 5.65 mm (range, 4 to 7.4mm, z-score -2.34±1.18, range from -4.52 to -1.35), significantly improved when compared to the preoperative value. (Figure 4) There was mild tricuspid valve regurgitation with no evidence of pulmonary hypertension.