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Ann Thorac Surg 2000;70:1907-1910
© 2000 The Society of Thoracic Surgeons

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Original article: cardiovascular

Impaired distensibility of neoaorta after arterial switch procedure

^a Department of Pediatric Cardiology and Pediatric Cardiovascular Surgery, The Heart Institute of Japan, Tokyo Women’s Medical University, Tokyo, Japan

Accepted for publication April 26, 2000.

Address reprint requests to Dr Murakami, Department of Pediatrics, Hokkaido University, School of Medicine, N-15, W-7, Kita-ku, Sapporo 060-8638, Japan
e-mail: murat{at}med.hokudai.ac.jp

	Abstract

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Background. Although the arterial switch operation has become the standard surgical procedure for treatment of complete transposition, postoperative problems have not been fully appreciated. One such problem may be the postoperative function of great arteries that are manipulated radically.

Methods. The diameters at four levels of the aorta were measured in 36 patients who had undergone arterial switch operation and the distensibilities were calculated. The data were compared with that of age-matched controls.

Results. At the level of the Valsalva sinus, aortic diameters after one-staged and two-staged operations were 137.0% ± 21.3%N and 152.4% ± 17.7%N of the normal aorta, respectively. The distensibilities at the Valsalva sinus in patients after one-staged and two-staged operations were 1.2 ± 0.7 and 1.5 ± 0.8 cm² · dyn^-1 · 10^-6, and at the supraaortic ridge were 2.5 ± 1.5 and 1.9 ± 1.5 cm² · dyn^-1 · 10^-6, respectively.

Conclusions. In patients after arterial switch procedure, the distensibility of the base of aorta is decreased. Long-term follow-up is necessary to clarify the influence of the "stiffness" of the base of aorta.

	Introduction

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The arterial switch operation has become the standard surgical procedure for treatment of complete transposition in the absence of an obstructed left ventricular outflow tract [1]. The potential postoperative problems, however, have yet to be elucidated fully. This operation involves radical manipulation of the base of the aorta, that is, transection and reanastomosis of both great arteries above the sinuses of Valsalva and transplantation of the coronary arteries. Sievers and colleagues [2] demonstrated that the neoaortic root in patients after two-staged arterial switch procedure was dilated and had impaired distensibility. They speculated that the cause of such change was the delayed pulmonary artery banding. We have had the impression that angiogram for patients after not only two-staged, but also one-staged arterial switch operation shows decreased distensibility of neoaorta. This observation implies that not pulmonary artery banding but arterial switch procedure itself causes the damage of the neoaorta. To clarify this hypothesis, we investigated the distensibility of neoaorta after arterial switch operation.

	Material and methods

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Patients
We enrolled 36 patients who had undergone the arterial switch operation for complete transposition or double outlet right ventricle with subpulmonary ventricular sep-tal defect after obtaining informed consent (Table 1). The study subjects included 27 boys and 9 girls (4.9 ± 2.8 years of age) and a postarterial switch operation period of 4.5 ± 2.7 years. Twelve patients underwent the operation with the two-staged arterial switch method, namely pulmonary artery banding with or without Blalock–Taussig shunt performed before the arterial switch procedure. Data were obtained from middle- or long-term follow-up cardiac catheterizations and angiographic investigations. Patients who had aortic regurgitation were excluded from this study.

Aortic diameter measurements
Aortic diameter was measured in the lateral view of the left ventriculogram (60 frames/second). To minimize the direct influence of contrast material injection on hemodynamics, measurements were made after one of the first two beats after injection of contrast medium into ventricles. Angiograms with ventricular ectopic beats were not used. The measurements of aortic diameter were made at four levels:

1. sinuses of Valsalva,
   
2. supraaortic ridge (which implies the level of suture, approximately),
   
3. the middle between level 2 and the first branch from aortic arch, and
   
4. the level at diaphragm (Fig 1).
   

View larger version (22K): [in this window] [in a new window]   Fig 1. The positions of measurement.

Calculation of aortic distensibility
Aortic distensibility was calculated using the following formula:

where change in aortic diameter = systolic minus diastolic aortic diameter, and change in aortic pressure = systolic minus diastolic pressure.

The use of this formula to estimate distensibility for vessels with thin walls in relation to lumen, such as the aorta, has already been reported [3, 4].

Data analysis
The diameters of the Valsalva sinus were compared with those of the normal aorta and the normal pulmonary artery [2] for their body surface area.

Although the aortic distensibility is age dependent, there are no data for normal children. Thus, we measured distensibilities from angiograms in patients (with Kawasaki disease, atrial septal defect, and pulmonary stenosis) who did not have a leak of aortic level (eg, patent ductus arteriosus, aortic regurgitation, etc.) using the same method. We adopted these data as "normal" control. We then compared the distensibilities in patients after arterial switch operation with those in age-matched controls.

Statistical analysis
All data were presented as mean values ± standard deviation. Differences in Valsalva diameter between one-staged and two-staged repair were determined by the standard unpaired t test. The distensibilities of the neoaorta were compared with those in age-matched controls using Wilcoxon signed rank test. A p value less than 0.05 was considered statistically significant.

	Results

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Size of valsalva
The Valsalva’s sinus diameter of neoaorta in systole was 142% ± 21% of the size of normal aorta and 133% ± 20% of the size of normal pulmonary artery [4]. The Valsalva’s diameter in patients who had undergone the two-staged repair was significantly larger than that in patients who had undergone the one-staged repair (Table 2).

View larger version (17K): [in this window] [in a new window]   Fig 2. Relationship between age and aortic distensibility at sinus portion (level 1). : normal control, : after one-staged arterial switch procedure, •: after two-staged arterial switch procedure (patients after arterial switch procedure versus normal control, z = -5.200, p < 0.0001; patients after one-staged arterial switch procedure versus normal control, z = -4.286, p < 0.0001; patients after two staged arterial switch procedure versus normal control, z = -2.903, p = 0.0037).

View larger version (17K): [in this window] [in a new window]   Fig 3. Relationship between age and aortic distensibility at suture line (level 2). : normal control, : after one-staged arterial switch procedure, •: after two-staged arterial switch procedure (patients after arterial switch procedure versus normal control, z = -4.949, p < 0.0001; patients after one-staged arterial switch procedure versus normal control, z = -4.229, p < 0.0001; patients after two staged arterial switch procedure versus normal control, z = -2.589, p = 0.0096).

View larger version (17K): [in this window] [in a new window]   Fig 4. Relationship between age and distensibility of ascending aorta (level 3). : normal control, : after one-staged arterial switch procedure, •: after two-staged arterial switch procedure (patients after arterial switch procedure versus normal control, z = -1.304, p = 0.1922).

View larger version (17K): [in this window] [in a new window]   Fig 5. Relationship between age and distensibility of descending aorta (level 4). : normal control, : after one-staged arterial switch procedure, •: after two-staged arterial switch procedure (patients after arterial switch procedure versus normal control, z = -0.762, p = 0.4461).

	Comment

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How does this impaired distensibility affect these patients? There are two possible effects. First, the decreased aortic distensibility may have influence on the aortic leaflet motion. Brewer and coworkers [5] demonstrated that the transmission of unnatural fatigue stresses to the leaflets occurred by the rigid aortic root. Thus, not only dilatation of the Valsalva sinus but also abnormal leaflet motion may induce aortic regurgitation, which is one of the serious complications after the arterial switch procedure [6]. Careful long-term observation will be needed to confirm this observation. Second, coronary blood flow may be altered by changes in the elastic properties of the neoaortic sinus. The decreased distensibility of ascending aorta causes the decrease of coronary blood flow [7, 8], and changes the coronary flow pattern [9]. Such change of coronary blood flow may occur in patients after arterial switch operation. We reported previously that the left coronary artery is hypoplastic after arterial switch operation [10], and thus, the decreased distensibility may have impaired the growth of coronary arteries in those patients. In fact, a few patients had remarkably small coronary arteries associated with low left ventricular ejection fraction (unpublished data).

Why does the arterial switch procedure make the neoaortic sinus dilated and stiff? There may be at least three possible causes. First, manipulation related to the operation (namely the suture of coronary buttons, etc.) may bring out such changes. Secondly, the dilation and stiffening may be due to the characteristics of the pulmonary artery in a high-pressure position. Although the histology of pulmonary root and aortic root are similar at birth [2], the muscle fiber composition is different [11]. Thus, the damage due to pressure load to the anatomic pulmonary artery may make the neoaortic sinus dilated and stiff. Thirdly, the change might be caused by damage to the "vasa vasorum." The vasa vasorum is a fine network of small vessels that contributes substantially to the outer layers of the aorta. The vessels exist in periaortic fat, and the blood flow in the wall of the ascending aorta and pulmonary artery is derived from the coronary arteries, bronchial arteries, and subclavian arteries [12]. The arterial switch operation impairs the vasa vasorum flow in the base of the neoaorta. Namely, the transection of pulmonary artery above the Valsalva sinus shuts off the blood flow from the upper side, and the manipulation related to the transplantation of coronary arteries intercepts the blood flow from coronary arteries. The removal of the vasa vasorum causes medial necrosis, which induces the dilatation and the impairment of distensibility of the aorta [13, 14]. Therefore, the dilatation and the decreased distensibility of the neoaortic sinus after arterial switch operation may be caused the disturbance of vasa vasorum flow. Further histologic examination is needed.

In evaluating the elastic property of aorta, it is better to integrate the unstressed radius to minimize the effect of aortic size. However, it is uncertain whether the pressure–strain curve is linear or not in our patients after arterial switch operation. Thus, we used a "simple" method to evaluate the elasticity.

	References

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1. Castañeda A., Jonas R., Mayer J., Hanley F. Cardiac surgery of the neonate and infant. Philadelphia: WB Saunders, 1994:409-438.
2. Sievers H., Lange P., Arensman F., et al. Influence of two-stage anatomic correction on size and distensibility of the anatomic pulmonary/functional aortic root in patients with simple transposition of the great arteries. Circulation 1984;70:202-208.[Abstract/Free Full Text]
3. Greenfield J.C., Patel D. Relation between pressure and diameter in ascending aorta in man. Circ Res 1962;10:778-781.[Abstract/Free Full Text]
4. Merillon J.P., Motte G., Fruchaud J., Masquet C., Gourgon R. Evaluation of the elasticity and characteristic impedance of the ascending aorta in man. Cardiovasc Res 1978;12:401-406.[Medline]
5. Brewer R., Deck J., Capati B., Nolan S. The dynamic aortic root. Its role in aortic valve function. J Thorac Cardiovasc Surg 1976;72:413-417.[Abstract]
6. Yamaguchi M., Hosokawa Y., Imai Y., et al. Early and midterm results of the arterial switch operation for transposition of the great arteries in Japan. J Thorac Cardiovasc Surg 1990;100:261-269.[Abstract]
7. Bogren H., Mohiaddin R., Klipstein R., et al. The function of the aorta in ischemic heart disease: a magnetic resonance and angiographic study of aortic compliance and blood flow. Am Heart J 1989;118:234-247.[Medline]
8. Ohtsuka S., Kakihana M., Watanabe H., Sugishita Y. Chronically decreased aortic distensibility causes deterioration of coronary perfusion during increased left ventricular contraction. J Am Coll Cardiol 1994;24:1406-1414.[Abstract]
9. Abel F. Influence of aortic compliance on coronary blood flow. Circ Shock 1984;12:265-276.[Medline]
10. Yatsunami K., Nakazawa M., Kondo C., et al. Small left coronary arteries after arterial switch operation for complete transposition. Ann Thorac Surg 1997;64:746-751.[Abstract/Free Full Text]
11. Sakurai H., Matsuoka R., Furutani Y., Imamura S., Takao A., Momma K. Expression of four myosin heavy chain genes in developing blood vessels and other smooth muscle organs in rabbits. Eur J Cell Biol 1996;69:166-172.[Medline]
12. Parke W. The vasa vasorum of the ascending aorta and pulmonary trunk and their coronary-extracardiac relationship. Am Heart J 1970;80:802-810.[Medline]
13. Stefanadis C., Karayannacos P., Boudoulas H., et al. Medial necrosis and acute alterations in aortic distensibility following removal of the vasa vasorum of canine ascending aorta. Cardiovasc Res 1993;27:951-956.[Abstract/Free Full Text]
14. Stefanadis C., Valchopoulos C., Karayannacos P., et al. Effect of vasa vasorum flow on structure and function of the aorta in experimental animals. Circulation 1995;91:2669-2678.[Abstract/Free Full Text]

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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): Makoto Nakazawa Yasuharu Imai Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Murakami, T. Articles by Imai, Y. Search for Related Content PubMed PubMed Citation Articles by Murakami, T. Articles by Imai, Y.