Thorax (1971), 26, 115.

Correction of persistent truncus arteriosusM. A. ROGERS, W. S. WINSHIP, and A. J. COLEMAN

Thoracic Surgical and Cardiac Units, Wentworth Hospital, and the Departments of Surgery,Medicine, and Anaesthetics, University of Natal

Successful correction of a type 2 truncus arteriosus in an African boy of 10 years is reported.The surgical technique employed is described and preoperative and late postoperative haemo-dynamic data are documented.

Failure of the primitive truncus arteriosus to parti-tion results in one of a group of congenital cardiacanomalies called persistent truncus arteriosus. Asingle vessel, guarded by a semi-lunar valve, leavesthe heart, and from this arise the coronary art-eries, the aorta, and the pulmonary arterial supply.Successful correction of this congenital anomalywas first recorded in 1968 (McGoon, Rastelli, andOngley, 1968). Wallace and his associates havereported successful total correction in fourpatients (Wallace, Rastelli, Ongley, Titus, andMcGoon, 1968). The purpose of this paper is torecord the surgical technique employed in thecorrection of a type 2 truncus arteriosus and tooutline the preoperative and late postoperativehaemodynamic state.

CASE REPORT

An African boy aged 10 years was referred from anoutlying hospital where he had been treated for pul-monary tuberculosis and congestive cardiac failure.He had suffered recurrent respiratory infections sinceinfancy and complained of palpitations and increasingdyspnoea on effort.

His weight was 51 lb (23 kg) and he was 4 ft 5j in(1-37 m tall). Cyanosis was not recognizable at restbut he became cyanosed, if only slightly, with exer-cise; the peripheral pulses were collapsing in charac-ter; the liver was palpable 2 cm below the right costalmargin. There was clinical evidence of both right andleft ventricular enlargement and a systolic thrill waspalpable at the left sternal border. A pansystolicmurmur (grade 4/6), maximal at the 4th interspace,and an early diastolic murmur along the left sternalborder were audible. At the apex a mid-diastolicmurmur and a third heart sound were heard. Thesecond heart sound was accentuated and single.The electrocardiogram showed a mean frontal plane

axis of +80° and evidence of bi-ventricular hyper-trophy.

Radiographically (Fig. la) the cardiothoracic ratiowas 0 58, the left atrium was enlarged, the ascending

aorta dilated, and the pulmonary segment concave.Both pulmonary arteries were large and arose highat approximately the same level.

Cardiac catheterization demonstrated equal systolicpressures in the aorta and right and left ventricles.The right and left pulmonary arteries were enteredseparately from the truncus, and there was not a sys-tolic gradient between the pulmonary arteries and thetruncus arteriosus. The oxygen saturation of arterialblood was 89 vol%. The ratio of pulmonary to sys-temic flow was 2x3 and pulmonary resistance was 38%of systemic resistance. The left-to-right shunt was cal-culated to be 68% of the pulmonary venous returnand the right-to-left shunt to be 27% of the systemicvenous return (Table I).

TABLE IRESULTS OF PREOPERATIVE CARDIAC CATHETERIZA-

TION

Pressures (mmHg) Blood OxygenSite SD Mean Saturation

SVC 71RA 5/1-5 3 73IVC 74RV 87/0-5 76RPA 87/42 62 88LA 12/6 8 95Aorta 87/50 65 89

Systemic blood flow (I/min,m') 5Pulmonary blood flow (1/min/mr) 11-5Pulmonary/systemic flow ratio 2-3PVR/SVR% 38

Angiocardiography showed a ventricular septaldefect and a truncus arteriosus with right and leftpulmonary arteries which arose from the dorsal aspectof the truncus arteriosus. There was minimal aorticregurgitation.

OPERATION Surgical repair, through a mediansternotomy, was undertaken on 25 November 1969with total normothermic cardiopulmonary bypass,using a prime of 5% dextrose water and a flow of2-46 1/min/m2. The truncus arteriosus was cross-clamped distal to the origin of the pulmonary arteriesand the left ventricle vented through its apex. Thepulmonary arteries arose separately but close, together

115

on March 31, 2020 by guest. P

rotected by copyright.http://thorax.bm

j.com/

Thorax: first published as 10.1136/thx.26.1.115 on 1 January 1971. D

ownloaded from

(b)

FiG. 1. (a) Preoperative postero-anterior chest radiograph. There isincreased pulmonary vascularity and flattening in the region normallyoccupied by the pulmonary trunk. The cardiothoracic ratio is 0.58. (b) Post-operative chest radiograph in the postero-anterior view showing theprominent pulmonary artery segment and a marked decrease in pulmonaryvascularity.

5i 7,V.:.,

.i

on March 31, 2020 by guest. P

rotected by copyright.http://thorax.bm

j.com/

Thorax: first published as 10.1136/thx.26.1.115 on 1 January 1971. D

ownloaded from

Correction of persistent truncus arteriosus

from the dorsal aspect of the truncus arteriosus.The truncus arteriosus was transected at the level ofthe pulmonary arteries, the incision being so arrangedthat it encircled the orifices of the pulmonary arteriesposteriorly. The valve which guarded the entranceto the trunvus had four cusps, one being divided bya median raphe. The right coronary artery aroseanteriorly and the left coronary artery posteriorly andto the right. Both coronary arteries were perfused.The distribution of the right coronary artery was

such that a right ventriculotomy for exposure of theventricular septal defect would have resulted in divi-sion of major coronary arterial branches. The ventri-cular septal defect, which was typically situatedimmediately below the truncal valve, was thereforerepaired from within the truncus arteriosus. A Dacronpatch was anchored to the rim of the defect usinginterrupted figure-of-eight sutures. The right ventri-cular cavity, at the site calculated to be that fromwhich, normally, the pulmonary artery should havearisen, was a thin-walled vestibule. The anterior wallof the right ventricle, at the site devoid of coronaryvessels, was excised so as to leave an elliptical defect,approximately 3 cm in length.A homograft which comprised ascending aorta,

aortic valve, and the anterior leaflet of the mitralvalve was used to fashion a pulmonary artery. Thehomograft had been sterilized in ethylene oxide andfrozen to -700 C for storage. The diameter of thegraft at the level of the aortic annulus was 26 mm.

mm.Hq200

IC

- LV ^

/\RV-l1f- ~~~~1-,IAI 11 l

FIG. 3. Postoperative right ventriculogram in the leftlateral view showing unimpeded flow through the homo-graft pulmonary valve and main pulmonary artery.Note the unusually anterior position of the surgicallycreated outlet of the right ventricle.

The distal anastomosis to the cuff of tissue which hadbeen left surrounding the orifice of the pulmonaryarteries was completed first, the homograft beingorientated to allow the anterior leaflet of the mitralvalve to lie anteriorly. Incorporation of the aorticleaflet of the mitral valve lent obliquity to the ana-stomosis between the right ventricular chamber andthe homograft valve, so that the valve lay in a trans-verse plane. Finally, continuity of the truncus arterio-sus, now ascending aorta, was achieved by end-to-endanastomosis.

Perfusion was discontinued after 120 minutes andthe haemodynamic status of the patient was imme-diately good. However, continued bleeding from theposterior aspect of the aortic suture line necessitatedthe re-institution of cardiopulmonary bypass. Thesuture line was reinforced and finally supported by aband of Teflon felt which served also to narrow the'truncus' and allow the aortic homograft to lie un-disturbed. Thereafter the patient made an uneventfulrecovery.The patient was readmitted three months after

operation for restudy. He was asymptomatic andactive. A grade 3/6 systolic murmur was heard, bestin the pulmonary area; a soft pansystolic murmur anda short diastolic murmur were heard at the left sternal

FIG. 2. A simultaneous recording of the pressures(mmHg) in the left ventricle (LV) and right ventricle(RV) three months after surgical correction.

i

- -~~~~~~

117

on March 31, 2020 by guest. P

rotected by copyright.http://thorax.bm

j.com/

Thorax: first published as 10.1136/thx.26.1.115 on 1 January 1971. D

ownloaded from

M. A. Rogers, W. S. Winship, and A. J. Coleman

border. Two components of the second heart soundcould be clearly distinguished.

Electrocardiography showed sinus rhythm and in-complete right bundle-branch block and the meanfrontal plane axis was + 800.

Radiographically the cardiothoracic ratio was un-changed (0-58), there was a prominent pulmonarysegment, and the lung fields appeared less plethoricthan before operation (Fig. lb).At cardiac catheterization right ventricular systolic

pressure was less than half that in the left ventricle(Fig. 2). The main pulmonary artery was enteredeasily and there was not a systolic gradient betweenthe distal pulmonary arteries and the right ventricle(Fig. 3). Oxygen saturation of arterial blood was 95vol%, of pulmonary arterial blood 79 vol%0, and ofmixed venous blood 76 vol%. Systemic blood flowwas calculated to be 6 1/minIM2 and pulmonary bloodflow 7 1/min/m2. There was a left-to-right shunt of16% at high right ventricular level. The pulmonaryvascular resistance was 19% of systemic (Table II).

TABLE IIRESULTS OF POSTOPERATIVE CARDIAC CATHETERIZA-

TION

Pressures (mmHg) Blood OxygenSite SD Mean Saturation

SVC 74RA 10/4 6 75IVC 77RV 58/5-12 79MPA 58/24 36 79RPA 58/20 79LA 17/12 15 95LV 130/8-14Aorta 130/75 96 95

Systemic blood flow (1/min/m') 6Pulmonary blood flow (1/min/m2) 7Pulmonary/systemic flow ratio 1-2PVR/SVR% 19 4

An indicator dye-dilution curve confirmed the pre-sence of a small left-to-right shunt. There was trivialaortic regurgitation.

DISCUSSION

Before the use of composite homografts of theascending aorta, aortic valve, and anterior leafletof the mitral valve for construction of the pul-monary artery, attempts at total correction oftruncus arteriosus failed. Failures were fromeither persistent low cardiac output or continu-ing haemorrhage (Cooley, and Hallman, 1966;McGoon et al., 1968). With the use of homo-grafts, haemostatic suture lines are more easily

achieved and the intact aortic homograft valvespares the right ventricle the additional burdenof pulmonary regurgitation in the presence of in-creased pulmonary vascular resistance. The sur-gical technique employed in this patient is essen-tially the same as that described by McGoon andhis colleagues; the ventricular septal defect was,however, closed from within the truncus arteriosus.Haemorrhage from the posterior aspect of theaortic suture line would probably have beenavoided by the insertion of a gusset of materialsuch as Dacron, as the wall of the truncusarteriosus is normally thin and does not withstandthe tension accepted by the normal aorta.

Collective studies have shown that the majorityof infants with truncus arteriosus die within thefirst six months of life (Edwards, Carey, Neufeld,and Lester, 1965). Pulmonary flooding is the causeof death. Patients most likely to survive infancyare those with small pulmonary arteries or in-creased pulmonary vascular resistance. While in-creased pulmonary vascular resistance promotessurvival beyond infancy it will also jeopardize thesuccess of total correction.The surgical management of patients with this

anomaly therefore appears to be the same as forventricular septal defects banding of the pul-monary artery or pulmonary arteries in theseverely ill infant, who is not a candidate for openheart surgery, in preparation for later total correc-tion. Total correction is undertaken when thepatient is large enough to allow the insertion ofan aortic homograft of adequate size for adultlife, provided the pulmonary vascular resistanceis less than some 0 75 times the systemic vascularresistance.

REFERENCESCooley, D. A., and Hallman, G. L. (1966). Surgical Treatment

of Congenital Heart Disease, pp. 185-189. Lea andFebiger, Philadelphia.

Edwards, J. E., Carey, L. S., Neufeld, H. N., and Lester, R. G.(1965). Congenital Heart Disease, vol. 1, p. 296.Saunders, Philadelphia.

McGoon, D. C., Rastelli, G. C., and Ongley, P. A. (1968).An operation for the correction of truncus arteriosus.J. Amer. med. Ass., 205, 69.

Wallace, R. B., Rastelli, G. C., Ongley, P. A., Titus, J. K.and McGoon, D. C. (1968). 'Complete Repair of Per-sistent Truncus Arteriosus Defects.' Read at the 48thAnnual Meeting of the American Association forThoracic Surgery, Pittsburg, Pennsylvania, April 24, 1968.

118

on March 31, 2020 by guest. P

rotected by copyright.http://thorax.bm

j.com/

Thorax: first published as 10.1136/thx.26.1.115 on 1 January 1971. D

ownloaded from