Atrial defect size after Blalock-Hanlon atrioseptectomy

Atrial Defect Size After Blalock-Hanlon Atrioseptectomy

EDWARD LAUREN GLENN

B. CLARK, MD J. SWEENEY C. ROSENQUIST,

Baltimore,

MD,

FACC

Maryland

In transposition of the great arteries, a Blalock-Hanlon closed atrial septectomy is performed to improve intracardiac mixing at the atrial level. Although the Blalock-Hanlon septectomy is a common surgical procedure in cyanotic congenital heart disease, it has not been adequately assessed pathologically. In 14 heart specimens from patients (aged 3 days to 19 years) with transposition of the great arteries and Blalock-Hanlon septectomy, the margins of the septectomy, fossa ovalis and atrial septum were identified. The total area of the septum and its defects was calculated using planimetry. The ratio of defect size to atrial septal area was expressed as percent communication, which ranged from 5 to 39 (mean 18) percent in eight specimens with intact limbus of the foramen ovale and 28 to 57 (mean 42) percent in six specimens in which the limbus had been excised. The finding that specimens in which the Blalock-Hanlon defect extended into the fossa ovalis had the largest total communication emphasizes that to obtain optimal bidirectional atrial mixing the surgeon should extend the Blalock-Hanlon procedure across the limbus into the foramen ovale.

In transposition of the great arteries, the rationale for performing a Blalock-Hanlon closed atria1 septectomy is to improve intracardiac mixing at the atria1 level. In this procedure the surgeon isolates the interseptal area of the right and left atria with a curved clamp and excises the posterosuperior portion of the septum through incisions in the free wall of the right and left atria. Enlargement of this interseptal defect is possible if the clamp is loosened momentarily and the edges of the septum along the clamp are pulled closer toward the operator and excised.lT2 Although the Blalock-Hanlon atria1 septectomy is a common surgical procedure in cyanotic congenital heart disease, the size and shape of the defect have not been adequately assessed anatomically or pathologically or related to clinical results. This paper describes the location and area of the Blalock-Hanlon atria1 septectomy in anatomic specimens, emphasizing the value of extending the incision into the area of the fossa ovalis. Materials From the Department of Pediatrics and Pathology. The Johns Hopkins University, Baltimore, Maryland. This study was supported by Grants 16466 and 06005 from The National Institutes of Health, Bethesda, Maryland. Manuscript received February 3, 1977, accepted March 16, 1977. Address for reprints: Glenn C. Rosenquist, MD, Department of Pediatrics, The University of Nebraska Medical Center, Omaha, Nebraska 66105.

and Methods

Heart specimens from the cardiac pathology collection at the Johns Hopkins Hospital with dextrotransposition of the great arteries and previously performed Blalock-Hanlon atria1 septectomy were examined. All specimens had been fixed in formalin and transferred to Kaiserling’s solution; the entire atria1 septum, fossa ovalis and atria1 septectomy could be identified in all specimens.

Specimens were from patients admitted to the Johns Hopkins Hospital from the late 1950’s through 1975. Hypoxemia and metabolic acidosis predating more effective intensive care programs undoubtedly contributed to the high (60 percent) postoperative mortality rate in the group of patients reported on from this institution in 1966.3

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size to atria1 septal area was expressed as percent communication. Included in the specimen review were three hearts from neonates less than 1 month of age, three from infants between 1 month and 1 year and eight from patients aged 1 year to 19 years. In nine cases, the Blalock-Hanlon atria1 septectomy had been performed recently (within 2 weeks of death); in the other five, death occurred 5 weeks or more after the BlalockHanlon atria1 septectomy. In the latter specimens the margins of the septectomy were always well healed and smooth.

60

50

c .o ;ii .p

40

i E s

30 I

:

l

I

Separate Combined Defects Defects FIGURE 1. Ratio of atrial defect size to atrial septal area (expressed as percent communication) in hearts with a Blalock-Hanlon defect. Specimens in which the Blalock-Hanlon defect remains separated from the fossa ovalis defect have a smaller percent communication than those in which the Blalock-Hanlon defect extends into the fossa ovalis. Open circles represent specimens with a naturally occurring secundum atrial septal defect contributing to the total percent communication. N = number of specimens.

The margins of the septectomy, fossa ovalis and atria1 septum were determined by manually securing the specimen in a fixed position with the atria1 septum under uniform tension in its natural anatomic curvature. Special care was taken to not distort the margins of the Blalock-Hanlon atria1 septectomy. The margins of the atria1 septum were identified by probing the medial wall of the right atrium with a stainless steel pin placed at right angles to the septum and marking the portions of the medial wall that were common to the right and left atria but that contained no free wall of either chamber. The outlines of this margin were transferred to graph paper and areas of the atria1 septum and defects were calculated using standard planimetry. The ratio of measured atrial defect

Results The percent communication for the Blalock-Hanlon atria1 septectomy alone or in addition to an ostium secundum atrial septal defect ranged from 3 to 57 (Fig. 1). It ranged from 3 to 25 in specimens in which the septectomy did not extend into the fossa ovalis (Fig. 2) and from 5 to 39 in specimens in which the septectomy was augmented by a secundum defect. Two of the latter specimens had a small secundum defect (2 and 3 percent communication, respectively), but one specimen had a larger secundum defect (20 percent communication) (Table I, Fig. 1). Specimens in which the Blalock-Hanlon atria1 septectomy extended into the fossa ovalis (Fig. 3) typically had the largest percent communication (26 to 57) (Table II, Fig. 1). The specimens with the largest percent communication were not necessarily those in which the septectomy had been performed more than 5 weeks before death because one infant aged 4 days had the largest ratio of atria1 defect size to atria1 septal area. Discussion It is now established that patients with transposition of the great arteries and a naturally occurring atria1 septal defect4,5 or balloon septostomy6y7 have an improved prognosis over patients wit,hout an atria1 site for bidirectional mixing between the two circulations. Frequently, however, the defect produced by balloon

FIGURE 2. Opened right atrium in a heart with transposition of the great arteries. The fossa ovalis (FO) and Blalock-Hanlon defects are separated by the limbus of the fossa ovalis. Ao = aorta; WC and WC = inferior and superior venae cavae; RPVs = right pulmonary veins.

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TABLE Separate

Blalock-Hanlon

and Fossa Ovalis Defects Area (mm2) Blalock-Hanlon Defect

Fossa Ovalis Defect

Case no.

Atrial Septum

:

214 297

39

1:

3 4 :

345 506 1066 545

1: 123 197 15

0 0

;

1340 1146

3::

TABLE

Age

Total Percent Communication

At Surgery

ia 17 2:

2::

395 0

At Death

2 2.5days mo

4mo 3 days

2.5 mo 1.5 yr 10 2 yr

2.5 mo 1.5 yr 12 2.5yryr

3.5 2 yryr

2:

19 3.5 yr yr

II

Combined

Blalock-Hanlon

and Fossa Ovalis Defects Area (mm2)

Case no.

Atrial Septum

Combined Defect

9 ::

145 195 166

37 66 94

:; 14

526 664 948

248 324 240

Percent Communication

septostomy becomes inadequate before the child has reached sufficient size and weight for a Mustard procedure. In these cases a Blalock-Hanlon atria1 septectomy often improves bidirectional shunting at the atria1 leve1.8,g While ventricular compliance and pulmonary blood flow are important to the success of the atria1 septectomy in improvement of atria1 mixing, a large atria1 communication seems to be the most desirable prerequisite.lOJl Our specimen review indicates that the largest percent communication is present when the limbus of the foramen ovale is included in the excised tissue. This may be the result of loss of structural integrity of the foramen

Age At Surgery

At Death

34 :;

2 days 5.5days 2 yr

3 days 5.5days 3 yr

47 49 41

5mo 1 yr 6 yr

51 yr mo 6 yr

portion of the septum so that the communication enlarges further as the atria with their septum enlarge with somatic growth. Of interest is that the largest percent communication found in a specimen without limbus excision had a naturally occurring ostium secundum atria1 septal defect, an infrequent finding in transposition of the great arteries.4 This study emphasizes that when closed atria1 septectomy is undertaken, particular attention should be directed to excision of the limbus of the fossa ovalis. With inclusion of the limbus in the surgical specimen, one can expect a larger atrial communication, which will optimize bidirectional interatrial mixing.

FIGURE 3. Opened right atrium in a heart with transposition of the great arteries to demonstrate the combined Blalock-Hanlon and fossa ovalis defect that results from excision of the limbus of the fossa ovalis. Abbreviations as in Figure 2.

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References 1. Blalock A, Hanlon CR: The surgical treatment of complete transposition of the aorta and the pulmonary artery. Surg Gynecol Obstet 90:1-15, 1950 2. Ochsner JL, Cooley DA, Harris LC, et al: Treatment of complete transposition of the great vessels with the Blalock-Hanlon operation. Circulation 2451-57, 1961 3. Cornell WP, Maxwell RE, Haller JA, et al: Results of BlalockHanlon operation in 90 patients with transposition of the great vessels. J Thorac Cardiovasc Surg 12:525-532, 1966 4. Liebman J, Cullum L, Belloc NB: Natural history of transposition of the great arteries. Circulation 40:237-262, 1969 5. Boesen I: Complete transposition of the great vessels: importance of septal defects and patent ductus arteriosus. Circulation 28: 885-887, 1963 6. Parson CG, Ashley R, Burrows FGO, et al: Transposition of great arteries: a study of 65 infants followed for 1 to 4 years after balloon

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septostomy. Br Heart J 33:725-731, 197 1 7. Neches WH, Mullins CE, McNamara DG: The infant with transposition of the great arteries. II. Results of balloon atrioseptostomy. Am Heart J 84:603-809, 1972 8. Bonham-Carter RE: Progress in the treatment of transposition of the great arteries. Br Heart J 35:573-577, 1973 9. Venables AW: Complete transposition of the great vessels in infancy with reference to palliative surgery. Br Heart J 28:335-341, 1966 10. Plauth WH Jr, Nadas AS, Bernhard WF, et al: Changing hemodynamics in patients with transposition of the great arteries. Circulation 42:131-142, 1970 11. Shaher RM, Kidd L: Hemodynamics of complete transposition of the great vessels before and after the creation of an atrial septal defect. Circulation 33, 34:Suppl 1:1-3-l-23, 1966

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