Thorax (1970), 25, 190.

Giant left atriumB. T. LE ROUX and M. S. GOTSMAN

The Thoracic Surgical and Cardiac Units of the University of Natal, Wentworth Hospital, Durban

Radiographic evidence of asymmetrical enlargement of the left atrium without atrial infarctionis presented. Giant atrial enlargement is rarely symmetrical, the atrial appendage can contributeto the enlargement, and the giant atrium can be effectively trimmed. This will reduce its size and,therefore, the space which it occupies, and will restore the anatomical relations of neighbouringstructures such as the main bronchi.

Enlargement of the left atrium is a feature ofmitral valve disease, whether the valve is stenotic,incompetent, or both. The left atrium may achieveproportions which have provoked use of descrip-tive terms such as 'giant', 'massive', or 'aneurys-mal'-most often when the mitral valve has beengrossly incompetent (Parsonnet, Bernstein, andMartland, 1946), but also with a predominantlyor exclusively stenotic valve (Venner, 1954; Kent,Fisher, Ford, and Neville, 1956). Apart from thehaemodynamic consequences of a greatly en-larged left atrial chamber, the very size of thechamber constitutes an important disadvantage,with compression and displacement of neighbour-ing structures. These purely anatomical considera-tions were the subject of most of the earlierdescriptions of the lesion, including probably theearliest-by Owen and Fenton (1901). Referenceto these earlier descriptions of the lesion are con-tained in the paper by Parsonnet et al. (1946).Daley and Franks (1949) described the clinicalfeatures and anatomical consequences-dysphagiafrom oesophageal displacement, with the oesopha-gus either grossly stretched and flattened, or com-pressed against the vertebrae, if it has not slippedto one or other side; splaying of the main bronchiand bronchial compression, sometimes sufficientto obstruct completely a lobar bronchus, especi-ally the left lower and the middle lobar bronchi;interruption of the left recurrent laryngeal nerve;and occasionally even erosion of the spine.Oesophageal compression against the vertebrae bymassive left atrial enlargement may not onlycause dysphagia but also oesophageal erosion withdeath from haemorrhage (Le Roux and Williams,1969).

It has been maintained that a giant left atriumexhibits symmetrical enlargement which is notmore than an exaggeration of the usual symmetri-

cal enlargement of the left atrium so common inmitral stenosis ; that it is unusual for the atrialappendage to share in the generally gross enlarge-ment; and that localized enlargements do notoccur unless there is an associated atrial infarct(Daley and Franks, 1949). The purpose of thispaper is to illustrate that truly giant left atrial en-largement is not, and in fact cannot be, symmetri-cal, that the atrial appendage may enlarge mas-sively along with the body of the left atrium, andthat amputation of a large part of a giant leftatrium contributes to rapid recovery when ob-struction at the mitral valve has been surgicallycorrected.The normal left atrium comprises much of the

posterior surface of the heart. The four pulmon-ary veins enter the left atrium at the corners of asquare, the sides of which are rarely longer than4 cm. Anterior to the entrance of the right pul-monary veins there is a width of left atrial wallseldom, unless surgically developed, greater than1 cm. posterior or postero-lateral to the atrialseptum and before the right atrium begins to formthe right heart border. The left pulmonary veinshave, anterior to their entrance into the left atrialchamber, an extent of left atrial wall greater thanthe right veins but normally not more than 2 or3 cm., and t,he left atrial appendage rides highon this aspect of the left atrium. Rostral to theorifices of the upper veins and caudal to thoseof the lower veins the extent of atrial wall isvariable but again small; the immediate posteriorrelation of the atrial wall between the veins is theoblique sinus. Standard anatomical illustrationsdepict the left atriu-m at the level of the transversesinus (Fig. 1), where a cross-section passes throughthe atrial appendages. The diminutive width ofleft atrium anterior to the right pulmonary veinsis well shown. S0ndergaard (1954) was the prime

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Giant left atrium

Pulmonary,Artery

TransverseSinus

\' Left Atrium '\~~~~~~Rig/t Lower

Left Lower Pulmnonary VeinPulmnonary Vein O Sinus

FIG. 1. Cross-section through the atria at the level ofthe appendages and transverse sinus, which serves toillustrate the relationship of the left anterior atrial wallto the transverse sinus, of the atrial wall between thevenous orifices to the oblique sinus, and the relativelylimited extent of atrial wall which lies anterior to thevenous orifices, especially on the right.

exponent of development of the cleft between theleft and right atria at this level for the purposesof circumferential passage of a constricting sutureabout an atrial septal defect for the purpose ofclosure of the defect without assistance fromcardiopulmonary bypass. Cross-sections at morecaudal levels (Fig. 2) serve to confirm that -thenormal left atrium is an almost exclusivelyposterior structure, and that, even on the left,

there is a small extent of left atrial wall in frontof the pulmonary veins.

In mitral stenosis left atrial enlargement is con-fidently recognized radiographically-by obtru-sion on the left heart border of the enlarged leftatrial appendage between the boss which repre-sents the right ventricular outflow or pulmonaryarterial segment, rostrally, and the left ventricularborder, caudally, and by the density of the bodyof the enlarged left atrium behind the ventriclesand the right atrium (Fig. 3). For this density tohave a sharply defined margin, it must lie in con-tact with and be contrasted against aerated lung,or have an edge in which there is calcium, and aca'cified atrial wall is excessively rare.The left atrium can enlarge to the right, to the

left, or both, in front of or behind the venousorifices; posteriorly and laterally, between thevenous orifices, and caudal to them; and also ros-trally, both anteriorly, in the transverse sinus, andposteriorly, ibut in this direction obstruction to en-largement is more consistently encountered, in theform of the pulmonary arterial trunk and its rightand left branches, and the tracheal bifurcationand the right and left main bronchi (see Fig. 11).

Illustrative radiographic evidence, supported byappropriate placement of cardiac catheters, andbronchography (Figs 4 to 10), substantiate thesestatements, and corroborative evidence has been

FIG. 2. Cross-section at the level of the 7th thoracic intervertebral disc, caudal tothe level of the atrial appendages, which serves to demonstrate the posteriorrelations of the left atrium.

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FIG. 3. Three examples of radiographic appearances unmistakably those of mitral stenosis. In (a), the heartis unusually slender but the left atrial appendage makes its accustomed appearance on the left heart border, andthe right-sided double contour, the consequence of left atrial enlargement posteriorly, between the venous orificesis clear. In (b), the cardiac contour is essentially the same, although the heart is much larger and there is considerableright atrial enlargement. The double contour at the right heart border is again clear. In (c), previous mitral valvulo-tomy with amputation of the left atrial appendage has modified the left heart contour. The left atrium consti-tutes much of the right heart border, projects beyond the right atrium, and its greatest right-sided extension isbehind the pulmonary hilum.

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(a) (b)FIG. 4. (a) Postero-anterior and (b) left oblique views which show gross left atrial enlargement, mainly to theright, and the oesophagus displaced posteriorly, but also 'slipped' so that there is atrial enlargement posterior tothe column of barium.

FIG. 5. The atrium is greatly enlarged, 'aneurysmal' to FIG. 6. Postero-anterior chest radiograph in which isthe left, and the enlargement is certainly not symmetrical, shown massive left atrial enlargement to the right and toIn this instance the greatest extent of left atrial enlarge- the left. Both heart borders are left atrium and there arement seen at thoracotomy was anterior to the left pul- bilateral double contours, on the right the consequence ofmonary veins. The left atrial appendage was enormous left atrial enlargement, behind the pulmonary hilum,but does not constitute any part of the cardiac silhouette with right atrial edge superimposed in front of the hilum;in the postero-anterior view. There is visible a double on the left, from left atrium posterior to the pulmonarycontour where left atrium and left ventricle are super- hilum, rostrally and caudally, superimposed on leftimposed and contrasted against aerated lung medially atrium and grossly enlarged left atrial appendage inin the 10th left posterior intercostal space. front of the pulmonary venous orifices.

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B. T. Le Roux and M. S. Gotsman

FIG. 7. A trans-aortic left atrial catheter demonstratesthe left atrial edge at the left heart border. At left thoraco-tomy, for mitral valve replacement in this instance, leftatrial enlargement was both in front and behind the leftpulmonary veins, predominantly behind, with a massivelyenlarged left atrial appendage. The double contour hereof left atrium against left atrium is clear; a cleft in theatrial wall is occupied by the lingular segment; the mtiostlateral extent of atrium, occupied by the catheter tip, liesposteriorly, and bulges laterally the pulmnonary ligament;the dense, more medial edge lies anteriorly, caudal tothe left pulmonary vein.

FiG. 7

FIG. 8. (a) Postero-anterior chest radiograph in which is shown massive left atrial enlargement, predominantlyto the left, but also to the right, with bilateral double contours. At left thoracotomy for mitral valve replacementthe left atrial enlargement was almost exclusivelv anterior to the left pulmonary veins, which were displaced farposteriorly, and the left atrial appendage was also massively enlarged. The relationship of the right-sided extension ofthe left atrium to the right pulmonary venous orifices was assessed from inspection and palpation of the interior of the leftatrium, and was exclusively posterior to the right venous orifices. (b) Post-operative postero-anterior chest radio-graph after mitral valve replacement and left atrial trimming, which was confined to that area of atrium in frontof, rostral and caudal to the left pulmonary vein.

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(a) (b)FIG. 9. (a) Postero-anterior chest radiograph which shows left atrial enlargement, predominantly to the right,with double contours; the left atrium forms nearly the whole of the right heart border. The caudal projectionwas seen at right thoracotomy for mitral valve replacement to lie posterior to the level of the venous orificesand to displace laterally the right pulmonary ligament. The rostral projection displaced forward the superiorvena cava and extended to the right in front of the right pulmonary vein. The triangular pulmonary opacity basedon the right heart border was the medial segment of the middle lobe, which was shrunken and partially airless.(b) Antero-posterior chest radiograph made on the day following mitral valve replacement and paring of theleft atrium through a right thoracotomy. The broad ellipse of left atrium excised almost encircled the rightpulmonary veins, the orifices of which were separated by II cm. from those of the left pulmonary vein.

FIG. IOa

Legend to Fig. lOa is on page 197, overleaf.

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B. T. le Roux and M. S. Gotsman

FIG. lOb

FIG. lOc FIG. lOd

Legend to Figs lOb, 1Oc, and lOd is on facing page.

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Giant left atrium

FIG. 1Oe

FIG. 10. These radiographs are of the same patient; (a) a postero-anteriorchest radiograph in which is shown enlargement of the heart predominantlyright-sided in a patient with pure mitral incompetence and a giant leftatrium. The antero-posterior bronchogram (b) shows the main bronchisplayed. (c) Two cardiac catheters have been passed, one transvenouslyJrom the arm into the right atrium, and here seen against the rightlateral wall of the right atrium, before the catheter turns upwards into theright ventricle and pulmonary artery, with the catheter well medial to theright heart border; the other, passed from the groin, up the aorta,through the left ventricle into the left atrium and right upper lobarpulmonary vein, and here seen to lie against the right heart border, therebyestablished as left atrium. (d) A postero-anterior chest radiograph madetwo weeks after mitral valve replacement with a Starr-Edwards prosthesis.The heart size is greatly diminished by amputation of a large ellipse of leftatrium, the incision extending from in front of the right pulmonary veins,caudally, and then medially and rostrally between the right and leftorifices, which, in this instance, were separated by a distance of 12 cm.A post-operative antero-posterior bronchogram (e) shows that the mainbronchi are no longer splayed.

obtained angiographically and with the heart ex-posed at thoracotomy. Right- or left-sided, orbilateral, double contours at the heart border arecommon radiographic features of giant atrium.For there to be double contours there must bebosses on the cardiac surface, with folds whichdistinguish the bulges, each contrasted againstaerated lung. Aerated lung must be interposed in

p

a cleft in the atrial wall, usually in relation to theatrial septum or the entrance of the pulmonaryveins, the orifices of which are seldom themselvesgreatly widened; or the opportunity for thedemonstration of radiographic contrast may occurwhere atrium and ventricle are superimposed,with lung between. The atrium enlarges asym-metrically and its surface is thrown into folds by

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FIG. 11. Post-mortem specimen in wvhich can be seen

splaying of the main bronchi so gross that their directionis almost transverse. The transected aorta is artificiallydisplaced upwards to facilitate vision. The left lower bron-chus was, in this instance, totally obstrticted by externalcompression. The massive dilatation of the left atrium ismainly between the right and left venous orifices and ex-

tends far catudally, and rostrally as far as a.djacent strutc-tiures permit.

venous attachments and where enlargement is dis-couraged by contact with structures relativelyresistant to displacement. When folds do not de-velop on the surface of the giant atrium and lungdoes not occupy a cleft in the atrial wall, the op-portunity for radiographic contrast is lost and inthese circumstances a double contour is not seen.The effect of surgical reduction in size of a

giant atrium can be judged radiographically (Figs8 to 10) and bronchographically (Fig. 10); itsvalue can only be assumed. In none of the speci-mens of resected atrium was there evidence ofatrial infarction.

REFERENCES

Daley, R.,and Franks, R. (1949). Massive dilatation of the left auricle.Quart. J. Med., 18, 81.

Kent, E. M., Fisher, D. L., Ford, W. B., and Neville, J. F. (1956).Mitral valve surgery and left heart catherization in giant leftatrium. Arch. Surg., 73, 503.

Le Roux, B. T., and Williams, M. A. (1969). Dysphagia megala-triensis. Thorax, 24, 603.

Owen, I., and Fenton, W. J. (1901). A case of extreme dilatation ofthe left auricle of the heart. Trans. clin. Soc. Lond., 34, 183.

Parsonnet, A. E., Bernstein, A., and Martland, H. S. (1946). Massiveleft auricle with special reference to its etiology and mechanism.Anier. Heart J., 31, 438.

Sondergaard, T. (1954). Closure of atrial septal defects. Acta chir.scand., 107, 492.

Venner, A. (1954). Massive left atrium and mitral valvotomy. Brit.mned. J., 1, 1359.

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