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Novel surgical approach ‘intrapulmonary-artery septation’ for Fontan candidates with unilateral pulmonary arterial hypoplasia or pulmonary venous obstruction

Department of Cardiovascular Surgery, Shizuoka Children's Hospital, 860 Urushiyama, Aoi-ku, Shizuoka, 420-8660 Japan

Received 16 November 2005; received in revised form 7 August 2006; accepted 16 November 2006

Presented at the joint 19th Annual Meeting of the European Association for Cardio-thoracic Surgery and the 13th Annual Meeting of the European Society of Thoracic Surgeons, Barcelona, Spain, September 25–28, 2005.

*Corresponding author. Tel.: +81-54-247-6251; fax: +81-54-247-6259.

E-mail address: sakamoto{at}jun.ncvc.go.jp (K. Sakamoto).

	Abstract

Top Abstract 1. Introduction 2. Materials and methods 3. Results 4. Discussion Conference discussion References

 
It is difficult to manage patients with single ventricular physiology and unbalanced pulmonary arteries. Since 1998, we started a novel approach [Intrapulmonary-artery Septation (IPAS)] to improve the result for those with severe unbalanced pulmonary arteries consisting of a well-grown pulmonary artery and an inadequately-grown pulmonary artery. The inadequately-grown pulmonary artery includes severe pulmonary arterial hypoplasia and pulmonary venous obstruction. This approach is based on the following concepts: (1) A reliable blood source should be secured to recover the inadequately-grown pulmonary artery; (2) Wasteful volume-load should be prevented for the heart; (3) Long stenosis or non-confluence of pulmonary artery should be avoided. IPAS primarily consists of (A) a Glenn shunt; (B) a systemic-pulmonary artery shunt; and (C) a septation-patch. Both (A) and (B) are adjoined on a well-grown pulmonary artery, and (C) is placed between (A) and (B). PAS brings two separate blood flows of a Glenn shunt to the well-grown side and SPS on the inadequately-grown side. IPAS was performed in 20 patients. Seventeen reached the Fontan operation. Eleven underwent postoperative catheterization and seven had acceptable-balanced pulmonary blood flow distribution. IPAS can pilot more complicated cases having severe unbalanced pulmonary arteries to the Fontan circulation.

Key Words: Fontan operation; Glenn shunt; Bidirectional Glenn shunt; Systemic-pulmonary arterial shunt; Pulmonary arterial hypoplasia; Pulmonary venous obstruction

	1. Introduction

Top Abstract 1. Introduction 2. Materials and methods 3. Results 4. Discussion Conference discussion References

 
It is essential for patients with single ventricular physiology that appropriate pulmonary circulation and cardiac function are important for reaching Fontan circulation.

Due to numerous modifications, the operative results of the Fontan operation were dramatically improved [1–5]. However, even now, patients with severe unbalanced pulmonary arteries may not always reach the Fontan operation [6–11]. We started a novel approach [Intrapulmonary-artery septation (IPAS)] to improve results for patients with severe unbalanced pulmonary arteries that consist of a well-grown pulmonary artery (well-grown PA) and the other inadequately-grown pulmonary artery (inadequately-grown PA). We shall report on our early experience.

	2. Materials and methods

Top Abstract 1. Introduction 2. Materials and methods 3. Results 4. Discussion Conference discussion References

 
From April 1998 to August 2005, 20 patients underwent IPAS. At the time of the operation, they were considered less than ideal candidates for the Fontan procedure because of unilateral severe pulmonary arterial hypoplasia (PAH) and/or pulmonary venous obstruction (PVO), even though they had the other well-grown PA with low pulmonary vascular resistance (PVR) [9]. IPAS was adopted for those with PAH at first, and then even for those with PVO.

Since it was difficult to confirm the correct resistance and blood distribution under these situations with massive aorto-pulmonary collateral arteries (APCAs), unilateral severe PAH was defined by the size, presence of massive APCAs and flow characteristics in the pulmonary artery (with little antegrade flow or retrograde flow) on cardiac catheterization and echocardiography.

The small pulmonary artery with non-confluent pulmonary artery (NCPA) and massive APCAs was also defined as PAH. PVO was defined by complete obstruction or evident stenosis of the pulmonary vein, with little antegrade or retrograde flow in the ipsilateral pulmonary artery. The finding of low or no intake on the pulmonary blood scintigraphy was useful to confirm the area of PVO.

Eleven of the 20 patients had unilateral severe PAH and five out of 11 had NCPA. The other nine patients had unilateral or partial PVO concomitantly with three unilateral PAH and one NCPA. Their detailed information is shown in Table 1. All but one had undergone 31 previous surgical procedures, including; bidirectional Glenn shunt (BGS) (n=4), hemi-Fontan (n=1), Fontan (n=1).

View larger version (24K): [in this window] [in a new window]   Fig. 1. Concept of IPAS. A Glenn shunt and SPS are adjoined on a well-grown pulmonary artery. A septation-patch is obliquely placed between these two blood sources and makes two separate blood flows of Glenn shunt to the well-grown side and SPS to the inadequately-grown side. Concomitant procedures which include correcting and eliminating morphologic abnormalities have to be done simultaneously. PA – pulmonary artery, PVR – pulmonary vascular resistance, SPS – systemic-pulmonary artery shunt, PVO – pulmonary venous obstruction, AVV – atrioventricular valve.

View larger version (54K): [in this window] [in a new window]   Fig. 2. Procedures of IPAS. The patient (pt. 3) had stenosis of SVC and left pulmonary artery hypoplasia with massive APCAs, after hemi-Fontan operation. IPAS for him was performed as follows. (1, 2) SVC and rt. well-grown pulmonary artery were opened. (3) A graft of SPS was set beside the SVC. (4, 5) A septation-patch of an expanded 0.1-mm thick polytetrafluoroethylene sheet was sutured obliquely and covered orifices of both the SPS and left pulmonary artery. (6) Finally, another larger patch was sewed on the SVC and pulmonary arteries including the septation-patch, to secure enough passage for the Glenn shunt. Fontan operation was completed 17 month later. (NCPA 1–3) In patients with NCPA, posterior wall continuity was usually reconstructed by native pulmonary artery. And an anterior roof of the pulmonary artery was made until a septation-patch by a fresh pericardial patch. A posterior half of SVC was directly sutured to anterior aspect of pulmonary artery. After these procedures, IPAS was performed as usual. SVC – superior vena cava, APCAs – aorto-pulmonary collateral arteries, SPS – systemic-pulmonary artery shunt, NCPA – non-confluent pulmonary artery.

All data were expressed as the mean±1 standard deviation. Analysis of the difference was appropriately made by the paired or unpaired Student's t-test or Mann–Whitney U-test continuous variable comparisons. Statistical analysis was carried out using Stat View (Abacus Concepts, Inc, Berkeley, CA). A P-value <0.05 was considered significant.

	3. Results

Top Abstract 1. Introduction 2. Materials and methods 3. Results 4. Discussion Conference discussion References

 
Among the 20 patients, all but one had stable post-operative course and there was no late death after IPAS, however, there was one hospital death. This occurred in the patient with asplenia syndrome and uncontrollable atrioventricular valve regurgitation. The mean systemic oxygen saturation before and late after IPAS was 79±7.6% and 85±4.4% (n=17: P<0.05). Mean atrial pressures were 6.8±2.7 mmHg and 6.8±2.1 mmHg (n=17). Mean cardio-thoracic ratio before, at discharge and late after IPAS were 56±7.8%, 56±5.1% and 53±4.9% (n=15), respectively. Twelve surgical procedures were added after IPAS in seven patients. They included the release of recurrent PVO (n=6), SPS (n=3), pulmonary artery augmentation (n=3), aortic valve replacement (n=2), atrioventricular valve plasty or replacement (n=3), and pacemaker implantation (n=2). In two of three patients to whom SPSs were added after IPAS, SPSs at the time of IPAS were occluded due to the competitive blood flow derived from the massive APCAs.

In the follow-up period ranging from six to 74 months, Fontan operations were completed in 17 of the 19 IPAS survivors.

The indication and management of the Fontan operation was as follows: (1) when the blood flow to the inadequately-grown PA increased and arterial oxygen saturation rose, cardiac catheterization was performed, (2) it was the indication to perform Fontan operation that the pressure of BGS was <15 mmHg, because a well-grown PA under these conditions was considered to be able to maintain fenestrated Fontan circulation when the inadequately-grown PA could not take an appropriate role, (3) the fenestration was added before the end of the operation in the case of the patient who could not maintain Fontan circulation under more than 16 mmHg of central venous pressure.

During the Fontan operation, the whole pulmonary artery except the site of the septation-patch became appropriately in size in most cases, especially with PAH.

Thirteen out of 17 patients did not need the fenestration. One hospital death occurred by accidental air-embolism and two late deaths occurred by an RS virus infection and an unknown cause.

Cardiac catheterization one year after Fontan operation was done in 11 patients (PAH:5, PVO:6). This revealed that the central venous pressure, PVR and systemic arterial oxygen saturation in room air were mean 12.1±1.6 mmHg (11–16), mean 1.7±0.5 U m² (1.1–2.9) and mean 94.2±2.0% (90–96.3), respectively. Among five patients who had PAH, four reached an acceptably-balanced pulmonary blood flow distribution and one had moderately-unbalanced distribution (inadequately-grown side<30%). Among six patients who had PVO, three reached an acceptably-balanced distribution, however, three patients had severely-unbalanced distribution with single-lung Fontan circulation that had over 95% of pulmonary blood flowing into a well-grown PA [11] (Table 2).

	4. Discussion

Top Abstract 1. Introduction 2. Materials and methods 3. Results 4. Discussion Conference discussion References

Under such situations, a staged approach with BGS became the most general selection as an intermediate procedure, because of its two major advantages; (1) it can reduce the workload of a single ventricle and preserve the ventricular function, which is accomplished by reduction of the systemic-pulmonary arterial connection without severe cyanosis, (2) thanks to the pulmonary arterial pressure under 15 mmHg, it can eliminate developing pulmonary vascular obstructive diseases [1,6–9,12,13]. However, we are still puzzled about the management of patients with severe unbalanced pulmonary arteries [10,14]. Some reports suggested that high PVR and PA distortion were risk factors of BGS [6–8]. In the report from Hawkins et al., two among the 38 patients who underwent BGS were converted to a classic Glenn shunt and SPS during the early postoperative period, though details of the reasons were unclear [7].

For reference, let us consider the patient with right well-grown PA, a severe hypoplastic left pulmonary artery and left massive APCAs, who has severe narrowing at the place of pulmonary artery coarctation after a right SPS [15]. BGS may bring a merit of volume reduction, however, the hypoplastic left pulmonary artery may not recover and the patient may not reach the Fontan operation. Furthermore, even if a patch enlargement is made for the narrowing of pulmonary artery coarctation, it may bring unexpected blood flow from left to right that is supplied by left APCAs, under the condition with a hypoplastic pulmonary artery and massive APCAs. A combination of a right BGS and a left SPS without pulmonary arterial plasty is thought to be more reasonable, however, it may bring NCPA. Treatment of the case that has fallen into severe unbalanced pulmonary arteries is difficult to recover perfectly.

IPAS was developed as a novel approach for these complicated patients, which is composed of a Glenn shunt, an additional pulmonary blood source and a septation-patch. Among the three components of IPAS, a Glenn shunt reduces the workload of the ventricle, and an additional pulmonary blood source like SPS brings a reliable blood source to recover the hypoplastic pulmonary artery. The septation-patch is the key to this novel approach. It separates the two blood sources, even though the additional source is adjoined to a Glenn shunt on the well-grown PA; and it enables pulmonary blood to flow through the whole pulmonary artery with the exception of the septation-patch.

As a result, IPAS has the following potentials: (a) to rescue the inadequately-grown PA without excessive volume-loading and a long NCPA, (b) to keep acceptable arterial oxygen saturation, and (c) to allow growth of the bilateral pulmonary arteries with the exception of the septation-patch. In fact, escalation of arterial oxygen saturation (79±7.6% 85±4.4%) and gradual growth of the inadequately-grown PAs were provided after IPAS, without a rise of atrial pressure and cardio-thoracic ratio. As a result, 17 out of 20 patients have reached Fontan operation without deterioration of the ventricular function. Eleven patients who were examined one year after their Fontan operation had acceptable homodynamic parameters and arterial oxygen saturation, and four among five patients had PAH reached the appropriate pulmonary artery, however, only three among six patients had PVO reached appropriate pulmonary artery. It seemed that IPAS was limited in its effectiveness for patients with PVO, although it was effective for most of the patients with PAH. However, we like to positively evaluate these results because the patients with PVO were usually out of indication of Fontan operation.

In addition, it became clear that IPAS has two other merits related to surgical technique and postoperative management, after some procedures were repeated.

From the surgical technique standpoint, in such a case in which the inadequately-grown PA had appropriately grown after IPAS, the following Fontan operation became easier and safer than those after other conventional staged approaches, because pulmonary arterial plasty did not have to be added; and removal of the septation-patch, SPS and reconstruction of extra-cardiac conduit were done in the same operative field. From the standpoint of postoperative management, there was little blood flow to the inadequately-grown PA with high PVR immediately after IPAS, and the blood flow increased slowly as the pulmonary artery grew appropriately. This provided easy management in the early postoperative period because of decreased volume-load, especially when cardiac function was deteriorated.

As mentioned above, it seemed that IPAS was considerably effective, however, we were not able to show the appropriate evidence of how the additional flow of IPAS should be selected and when the following Fontan operation should be performed in this series.

In fact, we experienced that more than half of the inadequately-grown PAs were recovered without pulmonary hypertension median 11 months later after IPAS, in which SPS were mostly selected in the following standards; the 3 or 3.5-mm diameter conduit for the patients under 10 kg; and the 4-mm conduit for those over 10 kg.

More evidence of efficacy and long-term follow-up are mandatory before a final conclusion is reached.

In conclusion, we speculate that IPAS can be a new option for patients with single ventricle physiology and severe unbalanced pulmonary arteries consisting of a well-grown PA and an inadequately-grown PA, even if the patients failed the staged approach with BGS and Fontan operation. IPAS can pilot complicated patients who do not have the indication for Fontan operation in conventional criterions to the Fontan circulation.

	Conference discussion

Top Abstract 1. Introduction 2. Materials and methods 3. Results 4. Discussion Conference discussion References

 
Dr E. Mostafa (Cairo, Egypt): Have you compared this group with the single-lung Fontan?

Dr Sakamoto: I have only 4 or 5 cases of single-lung Fontan circulation. And after introducing IPS, we have 3. We perform the single-lung Fontan circulation on 2 or 3. But the condition of those patients is not different from those after intrapulmonary septation.

Dr Mostafa: But my question, actually, if we consider this as single lung, whatever the cause of the hypoplasia of the pulmonary artery, absent or have been taken in the shunt, whatever, and you do it just a single-lung Fontan, and you compare this with the intrapulmonary septation, have you compared this single-lung Fontan and the intrapulmonary septation?

Dr Sakamoto: I cannot understand that.

I want to make two-lung group then, bilateral lung, I want to. But unexpectedly there are 3 patients who had single-lung circulation after intrapulmonary septation. Because of the pulmonary venous obstruction, we cannot make the low pulmonary resistance.

Dr H. Uemura (London, United Kingdom): This intentionally created non-confluent nature of the pulmonary artery can cause also problems. What is the recommended duration for this non-confluent situation?

And you demonstrated the growth of the pulmonary artery in terms of the size of the structure. The morphology is different somehow from the functional facility of the pulmonary circulation. How do you assess the latter?

Dr Sakamoto: It is very important. We have confirmed the problem and to estimate the problem at 6 months or later. And if the blood flow from the shunt to the lung is greater then increases, we come back to the Fontan circulation, if the patient's central venous pressure of superior vena cava is under 15 mmHg.

Dr J. Vazquez-Jimenez (Aachen, Germany): I have a technical question. Which kind of materials do you use to make the patch intrapulmonary and which size of conduit do you use the small size?

Dr Sakamoto: I use the 0.1 mm Gore-Tex for the intrapulmonary septation patch. And I make the patch, if possible, a little larger.

Dr Vazquez-Jimenez: And the shunts, which size of Gore-Tex shunts do you use, 5, 6, 7?

Dr Sakamoto: No, 3.5 or 4. And over 10 kg almost 4.

	References

Top Abstract 1. Introduction 2. Materials and methods 3. Results 4. Discussion Conference discussion References

 

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This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Kisaburo Sakamoto Akio Ikai Noritaka Ota Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Sakamoto, K. Articles by Ota, N. Search for Related Content PubMed PubMed Citation Articles by Sakamoto, K. Articles by Ota, N. Related Collections Congenital - cyanotic