1973;63;198-202Chest Saroia Bharati, Maurice Leo and Donald E. Cassels Aortico-Right Ventricular Tunnel

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Aortico-Right Ventricular Tunnel*

Saroia Bharati, M. D., Maurice Leo, M. D., F.C.C.P. * * and Donald E . Cassels, M.D., F.C.C.P.

We recently examined a rare congenital heart in which there was a c a d be- tween the aorta and right ventricle in an infant boy who died approximately six hours after birth. The aortic opening of the canal was above the right sinus of Valsalva and above the origin of coronary arteries, and the canal tunneled its way into the right ventricle forming a poach in the latter to the right side of parietal b a d The aortic valve was normally formed and the ventricular septum was intact. 'lbe supravalvular ridge of the right sinus of Valsalva was abnor- mally formed and this is considered to be an integral part of the malformation. We are caDing this aorticoright ventricular tunnel and we consider this to be analogous to aortico-left ventricular tunnel, previously described.

e have observed a case in which a canal ~t the present time, the other twin clinically does not have extended from an opening in the aorta, above any heart

the level of the sinuses of Valsalva, to an opening in POSTMORTEM EXAMINATION the right ventricle. To our knowledge, this has never Heart: The heart was enlarged and weighed 21 gm (nor- been reported. Such a canal, however, is reminis- mal heart for the weight of the child 9 gm). Externally, there cent of what Levy and associates' have called was an outpouching of the aorta on i b right anterior side

ao*ico-left ventricular hnneli-e where such a canal which was continuous with a membranous structure beneath

emptied into the left ventricle.

This infant was the second of twins-both boys. He weighed 4 Ibs 5 oz at birth; he breathed spontaneously, and his color was ink. Two and one half hours later his cry became weak, and shortly thereafter he was noted to be dusky and to have grunting respirations. He was aspirated and placed on oxygen. His course deteriorated rapidly, and four hours after birth his heart rate was 40, and apnea was present. Six hours after birth his heart tones became weak and irregular and he died.

'From the Pediatric Cardiolo Department, Pritzker School of Medicine, University of g icago; Congenital Heart Dis- ease Research and Training Center, Hektoen Institute for Medical Research; and Departments of Pathology-North- western University Medical School; Pritzker School of Medicine. University of Chicago; Abraham Lincoln School of Medicine, University of Illinois; Chicago Medical School, University of Health Sciences; and Loyola University Stritch School of Medicine, Chica o. This investigation was supportef by Grant HL.07605-10 from the National Institutes of Health, National Heart and Lung Institute, Bethesda, Md.

"Career Investigator and Educator, Chicago Heart Associa- tion.

Reprint requests: Dr. Lev, Room 429,637 South Wood Street. Chicago 6061 2

FIGURE 1. Antero-septa1 view: AD = anterior descending coronary artery; P = pulmonary trunk; A = aorta; Pr = out- pouching of the aorta (proximal chamber of tunnel); D = membranous structure beneath the aorta (distal chamber of tunnel); An = aneurysmal dilatation of right ventricle.

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AORTICO-RIGHT VENTRICULAR TUNNEL

FIGURE 2. R i h t lateral view: A = wsterior surface of aorta; Pr = outpouching of aorta (prolrimai chamber of tunnel); D = membranous structure beneath the aorta (distal chamber of tunnel); An = aneurysm of right ventricle; RC = right coro- nary artery; LC = left circumflex coronary artery; AS = aneurysmal dilatation of posterior aortic sinus of Valsalva (outpouching on the posterior side of the aorta).

the aorta, which in turn was continuous with a bulge of the right ventricle on its right side (Fig 1, 2) . A smaller out- pouching was present on the posterior side of the base of the aorta (Fig 2) .

The aortic orifice and valve were normally formed (Fig 3)

FIGURE 3. ~ e t t venmcular vlew ana view or base of aorta: Pr = proximal chamber of tunnel; 0 = opening from the proximal into the distal chamber of the tunnel; AV = aortic valve; LV = left ventricle. Arrow points to the left coronary ostium.

but the left cusp had an accentuated corpus arantii. Above the upper margin of the right sinus of Valsalva, there was a wide opening in the aorta which led into an aneurysmal formation ( Fig 3) . which corresponded to the outpouching of the aorta seen externally (Fig 1 ) (proximal chamber of tunnel). The wall of this chamber resembled but was not identical with the wall of the aorta grossly. This proximal chamber led into a distal chamber of the tunnel through an opening lined by a ridge (Fig 3). The wall of this distal chamber had the structure of fibrous tissue grossly. The distal chamber of the canal in turn tunneled its way into the right ventricle which was aneurysmally dilated in this region (Fig 1.4). The total length of the tunnel was 1.3 cm.

The left coronary ostium emerged .5 cm above the left sinus of Valsalva (Fig 3). The left coronary artery gave off the anterior descending artery which bifurcated into two branches and then gave off a small branch on the anterior wall of the left ventricle ( Fig 1 ). The right coronary ostium was not within the sinus of Valsalva, but arose from the distal chamber of the tunnel .9 cm below the opening in the aorta (Fig 2). It proceeded to the posterior wall of the right ventricle, giving off the posterior descending and also a branch to the left ventricle. The left circumflex arose from the distal chamber of the canal by a separate ostium 3 mm from the origin of the right coronary artery (Fig 2). This proceeded to supply the anterior and lateral walls of the left ventricle and anastomosed with the right coronary artery.

The sinuses of Valsalva were observed under the magnifi- cation of the dissecting microscope. The right sinus of Val- salva was abnormal (Fig 4). The supravalvular ridge related to this sinus was situated low, so that the right sinus was shallower than the other two on the aortic wall side. This ridge was irregular in contour, and hung Like a shallow ptecipice over the edge of the sinus with the adjacent wall of the aorta extending into and being part of the aneurysmal dilatation of the aorta ( proximal chamber of tunnel ) ( Fig 4 ) . In the depths of the sinus, the wall of the aorta was thickened, and part of the bottom of the sinus lay on the endocardium of the summit of the ventricular septum. The lower part of the posterior sinus of Valsalva was slightly aneurysmally dilated (Fig 4). Its supravalvular ridge was normal. The supravalvular ridge of the left sinus of Valsalva

FIGURE 4. Close-up view of the aortic sinus of Valsalva. A section has been taken out from the aortic-right ventricular tunnel. SRR = supravalvular ridge of right sinus of Valsalva; SRP = supravalvular ridge of posterior sinus of Valsalva; E l = edge of cut surface of aorta; E2 = edge of cut surface of proximal chamber of tunnel; E 3 = edge of cut surface of distal chamber of tunnel; 0 = opening of proximal to distal chamber of tunnel; R = ridge demarcating aneurysm of pos- terior sinus of Valsalva.

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FIGURE 5. View of tunnel from aorta to right ventricle. Rod is in the tunnel and it enters into the aorta and right ventricle. PB = parietal band; RV = right ventricle; A = aorta.

was present but very indistinct. Otherwise this sinus was normaL

There was hypertrophy and enlargement of the right atrium and right ventricle. Internally, the latter presented an aneurysmal formation above the parietal band ( Fig S), at the entry of the canal above described. The tricuspid orifice was slightly smaller than normal, and there was an atrial septal defect of the fossa ovalis type.

BHARATI, LEV, CASSELS

Histologic examination of the aorta, the adjacent proximal FIGURE 7. Wall of pouch adjacent to aorta (proximal chamber of tunnel). Weinert-van Gieson stain: X 39. W = wall of

FIGURE 6. Aortic wall and wall of adjacent pouch (proximal chamber of tunnel). Weigert-van Gieson stain; x 39. A = aorta; W = wall of adjacent pouch; S = spongiosa.

- pouch; S.= spongiosa-like tissue; V = valve-like structure.

and distal chambers of the tunnel and the right ventricular aneurysm showed the following: the aortic wall had a normal architecture (Fig 6). The wall of the adjacent proximal chamber showed the general elastic structure of the media of the aorta but towards the lumen there was loose spongiosa- like connective tissue (Fig 6, 7). This tissue at the lower part of the pouch was thrown up in the form of a small valve-like formation ( Fig 7). The wall of the distal chamber adjacent to the myocardium presented a deeper layer of fibrous tissue, and a superficial layer of spongiosa ( Fig 8). Here also there were projections of spongiosa resembling a small valvular structure. The right ventricular myocardium showed marked fibrosis with an infiltration of mononuclear cells. There was no evidence of sinusoids in the myocardium.

Our case is not an aneurysm of the right sinus of Valsalva which had ruptured into the right ven- tricle. For an aortic sinus of Valsalva consists of a space which is bounded by the supravalvular ridge, extending from one .commissure to another, the aortic wall beneath it, attached to the annulus fibrosus of the aortic valve, and the aortic cusp and its attachment to the aortic annulus. The opening of the canal in our case lies above the supravalvular ridge and hence above the sinus of Valsalva.

Our case resembles those described as aortico-left

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AORTICO-RIGHT VENTRICULAR TUNNEL

FIGURE 8. Wall of pouch adjacent to myocardium of right ventricle (distal chamber of tunnel ) . Hematoxylin-eosin stain; x 39. S = spongiosa; F = dense fibrous tissue; M = myo- cardium.

ventricular tunnel. In the latter, the opening in the aorta is likewise above the sinus of Valsalva but the canal eventually tunnels its way through the ven- tricular septum to enter into the left ventricle. Hence, we are calling our case aortico-right ven- tricular tunnel. Further similarity between our case and some cases of aortico-left ventricular tunnel is the abnormal origin of the coronary arteries. How- ever, our case does not show the abnormalities in the aortic valve seen in some cases of aortic left ventricular tunnel.

The pathogenesis of aortico-right ventricular tun- nel is unknown. The explanations given for aortico- left ventricular tunnel reviewed by Bove and Schwartz6 which might be pertinent to our case are: (1) that the tunnel represents an anomalous coronary artery; (2 ) that the tunnel represents a dissecting aneurysm related to Marfan's disease; and (3) that it is due to an abnormally formed supravalvular ridge.

We may rule out Marfan's disease in our case, since there is no evidence of excessive accumulation of ground substance associated with disruption of elastic tissue and the appearance of cysts and lacunae in the aorta. It is likewise difficult to envision that we are dealing with an abnormal

coronary artery, which is entering the right ven- tricle through a myocardial sinusoid (Levy and co- workers') since the histology of the canal in our case does not show the structure of a coronary artery or that of a sinusoid in the right ventricle. However, this cannot be completely ruled out, since secondary hemodynamic changes may have altered the original structure of the canal. The hypothesis of Bove and Schwartz6 is perhaps the most perti- nent in our case, that we may be dealing with an abnormal formation of the supravalvular ridge. For in our case the supravalvular ridge of the right sinus of Valsalva is abnormally placed, while that of the left sinus of Valsalva is indistinct.

Unfortunately, we have not been able to find details of the histogenesis of the supravalvular ridge in the literature. Its formation must be related to the fashioning of the aortic valve and the sinuses of Valsalva from the bulbar cushions, and perhaps is related to the formation of the beginning of the coronary arteries. The development of all these structures takes place from 9 to 40 mm,1° and the onset of the development of the coronary arteries occurs from 14 to 16 mm. Since the coronary arteries are abnormal in our case, the latter period is probably the time of the development of the malformation aortico-right ventricular tunnel. We may postulate that the abnormal formation of the supravalvular ridge leads to the weakness in the aorta above the ridge, producing an aneurysmal dilatation of the primitive aorta (proximal chamber of the tunnel), which secondarily makes a connec- tion to the left or right ventricle (distal chamber of tunnel). This weakness may be associated with a weakness in the aorta below the ridge, leading to abnormal sinuses of Valsalva, which are present in our case. And because of the abnormally shallow right sinus of Valsalva, and the indistinct supra- valvular ridge of the left sinus of Valsalva, the coronary ostia are displaced above the sinuses of Valsalva and the coronary arteries are maldevel- oped.

Hemodynamically aortico-right ventricular tunnel produces a picture of left-to-right shunt, occurring throughout fetal life and after birth-aortic regurgi- tation into the right ventricle. This produces pres- sure and volume hypertrophy of the right ventricle during fetal life and neonatally. We do not know if this would permit a sufficient time of survival to enable surgical intervention. The latter has been carried out successfully in aortico-left ventricular tunnel (five case^),^*^.^ and at least theoretically could be performed in aortico-right ventricular tunnel.

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BHARATI, LEV, CASSELS

ACKNOWLEDGMENTS: We are indebted to Dr. Richard 0. Peach, Richland Memorial Hospital, Department of Pa- thology, Olney, Illinois for the use of his material; to Mr. Milorad Ralevich for his technical assistance; and Florence Kotal for her typographic assistance.

1 Levy MJ, Lillehei CW, Anderson RC, et al: Aortico-left ventricular tunnel. Circulation 27:Wl-853, 1963

2 Morgan RI, Mazur JH: Congenital aneurysm of aortic tract with fistula to left ventricle. Circulation 28:589-594, 1963

3 Cooley RN, Harris LC, Rodin AE: Abnormal communica- tion between the aorta and left ventricle. Aortico-left ventricular tunnel. Circulation 31 :564-571, 1965

4 Roberts WC, Morrow AG: Aortico-left ventricular tunnel. A cause of massive aortic regurgitation and of intracar- diac aneurysm. Am J Med 39:862-687, 1965

5 Edwards JE: Atlas of Acquired Diseases of the Heart and

Great Vessels. Philadelphia, W B Saunders Co., 1961, vol 111, p 1142

6 Bove KE, Schwartz DC: Aortim-left ventricular tunnel. Am J Cardiol 19:696-709, 1967

7 Bernhard WF, Paluth W, Fyler D: Unusual abnormalities of the aortic root or valve necessitating surgical correction in early childhood. New Eng Med 282:88-71, 1970

8 Neff U: Two observations of an "aortico left ventricular tunnel." Arch Kreislaufforsch 63:266-287, 1970

9 Fishbone G, DeLeuchtenberg N, Stansel Jr HC: Aortico- left ventricular tunnel. Radiology 98:579-580, 1971

10 Van Mierop LHS: In The Ciba Collection of Medical Illustrations, vol 5, sec 3, Embryology, prepared by Netter PH, edited by Yonkman FF. Summit, NJ, Ciba Publica- tions, 1969, p 126

11 Patten BM: The development of the heart. In The Pa- thology of the Heart and Blood Vessels, ( 3rd Ed ) Could SE ( e d ) . Springfield, Illinois, Charles C Thomas, Pub- lisher, 1968, p 64

From an Oration at Harvard University

Here in this university there is performed the miracle which distinguishes civilized man from all other animals. H e can transmit from one generation to another the knowledge h e discovers, the skill which he acquires, the wisdom which he perceives. But though man has the faculty of tradition, it is an uncertain one. Oftener than not he has been unable to absorb and to transmit the vital essence of his tradition. Then he has fallen into dark ages when he has lost his inheritance, into dull ages when he is uninterested in it, and into ages of bewilder- ment when he cries out for it and cannot find it. So the history of man is heavy with the tragedy of his unreal- ized possibilities. For had he been able to transmit the

human heritage unimpaired in its full vitality from ancient times to the present day, so that no skill was lost and none of the lessons of experience forgotten, the compounded wisdom of mankind would have produced a civilization so splendid as to surpass our ability to imagine it. But again and again the tradition of the good life has become dim and has been interrupted and then it has had laboriously to be rediscovered and realized and learned once more.

Lippman W, in Rositter C and Lare J (editors): The Essential Lippman,

New York, Random House, 1963

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1973;63; 198-202ChestSaroia Bharati, Maurice Leo and Donald E. Cassels

Aortico-Right Ventricular Tunnel

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