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J Thorac Cardiovasc Surg 2007;134:496-501
© 2007 The American Association for Thoracic Surgery
a University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
b Leiden University Medical Center, Leiden, The Netherlands.
Received for publication February 4, 2007; revisions received March 15, 2007; accepted for publication March 20, 2007. * Address for reprints: Y. L. Douglas, MD, Department of Cardio-thoracic Surgery, University Medical Center Groningen, PO Box 30001, 9700 RB Groningen, The Netherlands. (Email: Y.L.Douglas{at}thorax.umcg.nl).
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Dr Wijkstra
Bronchoscopic findings were within normal limits. Pulmonary function tests showed mild bronchial obstruction with normal static volumes (Table 1). We also performed ventilation–perfusion lung scintigraphy, which revealed nearly symmetrical ventilation (right 58%, left 42%) but very asymmetrical perfusion to the detriment of the left lung (right 87%, left 13%) (Figure 2, A and B).
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Dr van den Broek
Cardiac auscultation was completely normal. The electrocardiogram showed signs of right ventricular overload, and transesophageal echocardiography showed turbulent flow at the level of the right pulmonary veins (PVs), together with mild mitral valve regurgitation. Cardiac catheterization showed pulmonary arterial hypertension (40/15–28 mm Hg), discrepant high left pulmonary artery wedge pressure (30 mm Hg) compared with the left ventricular end-diastolic pressure (14 mm Hg), together with a high pulmonary vascular resistance (PVR): 9.5 Wood units (left); 5 Wood units (right). There were no signs of coronary artery sclerosis.
Dr Douglas
Dr Wolf, could you please describe the chest computed tomographic (CT) and angiographic findings?
Dr Wolf
Cardiac-triggered multidetector CT during intravenous contrast administration demonstrated bilateral pulmonary arteriovenous malformations most pronounced on the left side (Figure 3, A and B). Magnetic resonance angiography was performed to clarify flow directions in the arteriovenous malformations, but it left the origin of the tortuous PVs unclear. Stenosis of the PVs at the level of the entrance in the left atrium (LA) was most pronounced on the right side. A digital substraction angiogram of the pulmonary vessels confirmed a much smaller caliber of the left pulmonary artery compared with the right, together with a corresponding difference in lung perfusion. The left PVs seemed to be aberrant and varicose but not stenotic.
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Dr Ebels
On the basis of these findings, surgical resection of the stenotic parts of the right PVs was suggested without intervention on the left side because of its underdeveloped pulmonary vasculature and its aberrant but uninterrupted inflow of the PVs into the LA. Besides that, inspection and possible repair of the mitral valve was indicated.
By means of a median sternotomy, both lungs could be inspected. They had an abnormally pale appearance with multiple small vessel injections, more pronounced on the left side, so that a lingular as well as a middle lobe biopsy was done. Intrapericardially, the right superior and inferior PVs were macroscopically stenotic at the entrance to the LA. On the left side, a small vein resembling a left superior caval vein was seen together with a vein to the lower lobe. The origin and course of these veins were not visible. By inspection inside the right atrium, the possibility of a left superior caval vein could be rejected. After atrial septotomy, the entrance of the left-sided veins in the LA could be passed and appeared not to be stenotic. However, on the right side the diameters of the superior and inferior PVs at their entrance into the LA were only 4 and 7 mm, respectively. The mitral valve was sufficient and structurally normal. Both right PVs were incised longitudinally into the LA. The circumscript stenotic parts were resected, which resulted in an increase in diameter to 12 and 13 mm, respectively. A so-called sutureless pulmonary venoplasty1,2
was performed by suturing the LA wall to the pericardium posteriorly and using an autologous pericardial patch anteriorly. The postoperative course was uncomplicated.
Dr Douglas
The lung biopsy specimens were sent for pathologic analysis in Groningen, and the resected stenotic parts of the right-sided PVs were analyzed in the Department of Anatomy and Embryology of Leiden. Dr Timens and Dr DeRuiter, could you describe the histopathologic findings?
Dr Timens
Histologic examination of the pulmonary biopsy specimes revealed serious vascular disease with asymmetric and eccentric obliteration of venous as well as arterial branches, most pronounced on the left side, to be interpreted as postthrombotic vasculopathy. Thereby, extensive hemosiderosis was seen on the right side.
Dr DeRuiter
Staining of the stenotic rim revealed a large mass of collagen (Figure 4, A and B).
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Dr Wijkstra
After 1 year’s follow-up, the ventilation–perfusion mismatch between the right and left lungs was exactly the same as preoperatively. Exercise capacity, assessed by cycle ergometry, had not improved. Maximal oxygen uptake was 71% of predicted at a maximal work load of 90 Watts (78% of predicted) Large disturbances in gas exchange were shown during the test compatible with large ventilation–perfusion mismatch. Also, these findings were comparable with the preoperative situation (Table 1). It was decided to be expectant about probable future effects of dead space ventilation on the left side.
Dr Douglas
Dr Wolf, can you describe the chest CT findings of the repaired right PVs 1 year postoperatively?
Dr Wolf
High-resolution CT demonstrated nonstenotic venoatrial transitions on the right side (Figure 5). In relation to the right inferior PV, the right superior PV had a smaller caliber and a more tortuous course.
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The stenosis can also be acquired, called pulmonary veno-occlusive disease (PVOD), a condition for which various agents can be responsible.5,6 Especially in adults, it can be very difficult to determine whether the origin of the anomaly in a particular patient is congenital, acquired, or a combination of both.7 Extremely uncommon is a PV varix,8 which can be associated with a diseased mitral valve.9
When PV stenosis is congenital, two different types can be distinguished.10 In the first, the so-called hypoplasia of the PVs, narrowing involves the intrapulmonary and extrapulmonary part of the PVs for a variable distance. The second type is characterized by narrowing at the venoatrial junction, commonly called localized PV stenosis.
Dr DeRuiter
In normal development, the embryonic heart is connected to the mediastinum by the dorsal mesocardium. The major part of this structure regresses, after which, at the end of the fifth embryonal week, the lumen of the common PV develops in the remaining part of the dorsal mesocardium and the common connects with the peripheral PV system.11-13 By this point, the lung buds, which drained via the splanchnic plexus into the cardinal and umbilical veins, drain directly via the common PV into the LA. The connections with the splanchnic plexus and the umbilical and cardinal venous systems become of less importance and regress. The common PV is then incorporated into the posterior LA wall, finally resulting in four individual PVs entering the LA. On the left side also, two PVs forming one common PV ostium that enters the LA are seen.14,15
If atresia of the common PV occurs very early in development, total anomalous PV drainage develops and the embryonic systemic venous connections do not regress but establish a supracardiac or infracardiac drainage unless the PVs drain into the right atrium. If stenosis of the common PV occurs later, incorporation is disturbed, which may result in cor triatriatum.3,4 Atresia or stenosis of the left or right common PV leads to partial anomalous PV drainage so that the ipsilateral systemic venous drainage persists. If stenosis occurs very late, after PV incorporation has been completed, stenosis or atresia of individual PVs is the result. During fetal life, the hemodynamic effect of partial obstruction of one or more PVs may not be enough to preserve embryologic (systemic) venous drainage.16,17 After delivery, an increasing amount of blood volume reaches the lungs by which the hemodynamic effect of individual PV stenosis can be more pronounced.
Dr Douglas
If necessary, therapeutic options are percutaneous transluminal balloon angioplasty, stenting, or surgical resection.
Dr Timens
Acquired PV stenosis or PVOD is characterized by extensive and diffuse occlusion of PVs by fibrous tissue. Usually the (eccentric) intimal thickening involves venules and small veins but, occasionally, also larger veins and, in later stages, arterioles. The media of the veins may become arterialized with an increase in elastic fibers. The most consistent early parenchymal change is interstitial edema, which may progress to deposition of collagen fibers in the lobular septa and alveolar walls, as often observed when histologic features are obtained.18 Lymphatic vessels are dilated. A more obvious finding, in particular in later stages, is hemosiderosis, found commonly in alveolar macrophages or less commonly also in the interstitium.
Dr Douglas
Clinically, patients have pulmonary arterial hypertension without elevation of the pulmonary arterial wedge pressure.7,18 Many agents may be responsible for the etiology of PVOD. Infectious, genetic, and toxic factors have been described, as well as a thrombotic diathesis and autoimmune disorders.18 Because PVOD is a rare condition, no randomized therapeutic trials have been undertaken to compare the effect of current treatment modalities, that is, vasodilators, immunosuppresives, anticoagulants, and oxygen, on outcome. Because the prognosis is usually bad within 2 years after diagnosis, lung transplantation seems the only option for significantly prolonging life expectancy.
A PV varix is also a very uncommon anomaly that can be congenital or acquired. The congenital form usually is asymptomatic. The acquired form develops as a result of obstructed PV drainage and presents with symptoms of the underlying disease causing PV hypertension, for instance mitral valve disease or PV stenosis. Treatment consists of observation. If size increases or in case of hemoptysis, surgical treatment is indicated.8
Dr Douglas
In our patient, the etiology of the right-sided focal PV stenosis at the venoatrial junction is likely to be congenital in view of the combination with a diseased (nonfunctional) left lung. Acquired central PV stenosis in combination with a nonfunctional left lung would be very unlikely, because in hemodynamically comparable situations of normal PVs in patients who have had pneumonectomy, subsequent development of contralateral pinpoint central PV stenosis is very uncommon. However, an additional acquired component in this region must have been responsible for the progression of the dyspnea; the function of the left lung decreased and flow to the right lung subsequently increased, thereby inducing intimal proliferation at the right venoatrial junction to a critical point by means of altered flow profiles as turbulence.19 Nonetheless, the significant ipsilateral hemosiderosis with moderate obliteration of small veins and arteries in the biopsy specimen, together with a normal right-sided pulmonary arterial wedge pressure, suggests a possible superposed PVOD. On the left side, the small-caliber pulmonary artery, the elevated pulmonary artery wedge pressure, and the decreased perfusion of the left lung because of a very high PVR in combination with histologic fibrotic changes mimicking microinfarction suggests left-sided PV atresia. Considering the two apparently normal left PV ostia entering the LA and the nonhypoplastic left lung, this atresia must have developed during the late fetal period. After this, and under pressure, the varicose vein must have developed and connected with both left PVs, after which left-sided PV drainage was delayed but uninterrupted. If we deal in this case with some degree of PVOD in the right lung, careful follow-up is necessary because of its aggressive behavior. Now that the venous flow of the right lung to the LA is unobstructed, theoretically, dead space ventilation on the left side will increase. So long as this patient is doing well, an expectant policy is warranted. Thus, for ethical reasons, we have not yet performed a postoperative recatheterization. If her situation deteriorates, cardiac recatheterization should be performed. In case of increased dead space ventilation on the left side, combined with acceptable PA pressures and PVRs on the right, a left pneumonectomy would be an option. In case of an irreversible increased right-sided PVR and a very bad clinical condition, this patient should be screened for lung transplantation.
In conclusion, differentiation between congenital or acquired stenosis of PVs or a combination of both can be very difficult. However, cardiac catheterization and a lung biopsy can bring more clarity. This is necessary inasmuch as the acquired form behaves more aggressively than the congenital version and needs a closer follow-up because of its tendency to relapse and its worse prognosis in the long term.
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Footnotes |
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From the University Medical Center Groningen, University of Groningen, The Netherlands.
Cardiovascular and Thoracic Surgery
From the Leiden University Medical Center, Leiden, The Netherlands.
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-smooth muscle (SM) actin (A) and Resorcin-Fuchsin (RF) (B), showing severe intimal proliferation (I) by means of a stenotic rim of collagen without elastic fibers. L, Lumen; M, media; A, adventitia. Scale bars are 600 µm.