A reappraisal of the sinus venosus defect

Abstract

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OBJECTIVES

The phenotypic features and morphogenesis of the ‘sinus venosus defect’ remain controversial. The phenotypic features are anomalous systemic connections of 1 or more pulmonary veins that retain their left atrial connection, usually associated with a biatrial connection of the superior caval vein. Cases with these features, however, have not always been described as sinus venosus defects.

METHODS

We reviewed the findings documented in the literature from 11 patients with a biatrial connection of the superior caval vein, most reported following an autopsy examination. We compared these findings with the anatomical details of 50 patients undergoing surgical correction in our centre, paying particular attention to the override of the superior caval vein.

RESULTS

In only two-thirds of those undergoing surgery did the superior caval vein override the rims of the oval fossa, with the degree of override >50% in only 2 individuals. It is only these latter 2 cases that are directly comparable to the reported cases of biatrial connection of the superior caval vein.

CONCLUSIONS

Our comparisons provide new insights into the developmental background and phenotypic features of the superior sinus venosus defect. The defects exist because of the anomalous systemic connection of the pulmonary veins that retain their left atrial connections but not always in association with a biatrial connection of the superior caval vein. In extreme cases, nonetheless, they can underscore the connection of the caval vein to the morphologically left atrium, frequently described previously as a ‘biatrial connection’. The sinus venosus defect is better considered a venovenous malformation than a septal defect.

INTRODUCTION

The term ‘sinus venosus defect’, as far as we can establish, did not enter the lexicon of congenital cardiac malformations until Ross described a case in this fashion in 1956 [1]. It is intriguing, therefore, to note that, 100 years prior to this description, Peacock provided an accurate assessment of the morphological features of the lesion [2]. Consensus is now growing to show that the phenotypic feature of the overall group of so-called sinus venosus defects is an anomalous systemic connection of part of the pulmonary venous return to the right lung, with the pulmonary vein or veins retaining their left atrial connection [3, 4]. It is also usual, in this setting, to find that the orifice of the systemic vein receiving the anomalous pulmonary vein or veins overrides the rims of the oval fossa. Hearts having a biatrial connection of the superior caval vein in association with a partially anomalous pulmonary venous connection, particularly when the degree of override has been such to place the caval vein predominantly in connection with the morphologically left atrium, have not always been described as ‘sinus venosus defects’. This is not surprising, because examples, such as the description provided by Nutzel in 1914 [5], although postdating the account of Peacock [2], predated the coining of the term ‘sinus venosus defect’ by Ross [1]. On searching the literature, we discovered several additional cases with these features not described as showing ‘sinus venosus defects’ [6–14]. Having assessed the reported anatomical features of these cases, and despite the fact that the superior caval vein in this setting communicates mostly with the left atrium, it is our belief that all are examples of what we now recognize as the superior sinus venosus defect. The discussion of the findings by the original investigators provides insights into the morphogenesis of the lesion. Recent findings in terms of normal cardiac development, however, show that several of the proposed theories of morphogenesis no longer withstand rigorous scrutiny. The underlying concepts proposed to account for the association of the anatomical findings, nonetheless, are remarkably similar. In this review, we discuss the significance of our findings in relation to the modern-day understanding of the sinus venosus defect.

METHODS

Ethical statement

This study conforms to the principles outlined in the Declaration of Helsinki and was approved by the institutional ethics committee, All India Institute of Medical Sciences, New Delhi, India (Ref. No. IECPG-491/18.10.2018, RT-19/19/12/2018, dated 24 December 2018).

Data collection

Data were collected from the 11 published case reports of the so-called biatrial connection of the superior caval vein, with the arrangement resulting in significant systemic venous drainage directly to the morphologically left atrium. We compared the descriptions with the clinical and intraoperative findings of 50 patients who underwent repair of the overall spectrum of superior sinus venosus septal defects at our institution between January 2007 and December 2019.

Patients were enrolled in the study protocol after we obtained informed written consent from the patients themselves or their guardians. We searched the literature to identify the described instances of a biatrial connection of the right superior caval vein as described in association with a partially anomalous connection of the right pulmonary veins, but in the absence of a diagnosis such as a ‘sinus venosus’ defect. Having identified such cases, we evaluated the clinical and autopsy findings, assessing any problems encountered in the establishment of the diagnosis, the presence of associated cardiac and non-cardiac anomalies, surgical techniques used in treatment and their outcomes. The search engines used were Medline, PubMed, Google Scholar, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, ACP Journal Club and Ovid Embase. The search included literature in all languages. This strategy yielded 11 reports that provided the best answers to these topics. We have synthesized all available data to outline the issues of concern, diagnostic clues and the various techniques performed to repair primary as well as concomitant anomalies. We then assessed these descriptions in the context of our own extensive surgical experience with the overall spectrum of sinus venosus defects, recognizing that it was likely that only a small proportion of our patients would be directly comparable to those previously described in terms of the biatrial connection of the superior caval vein. We combined these interpretations with our knowledge of normal cardiac development and normal postnatal anatomy, hoping to improve the understanding of the phenotypic features of the sinus venosus defect [15, 16].

In our previous work, we designed a composite atrial turn-down reconstruction of the superior caval vein with preservation of the cavoatrial junction and the artery to the sinus node and assessed the long-term surgical outcomes of the procedure. In the current study, we did not repeat that analysis. Instead, we analysed the pattern of anomalous pulmonary venous drainage and the degree of override of the superior caval vein across the oval fossa in the patients with a superior sinus venosus defect. Our analysis, therefore, is based on a review of 11 case reports along with incorporation of preoperative echocardiographic, computer tomographic angiocardiographic and intraoperative findings on the anatomical details of patients who underwent repair of the overall spectrum of superior sinus venous defects using the double-barrel technique [15, 16].

Acquisition and analysis of the computed tomographic angiocardiographic data sets

All scans were performed on a second- or third-generation dual source computed tomography (CT) scanner (SOMATOM FLASH or SOMATOM FORCE, Siemens Healthineers, Erlangen, Germany). No form of heart rate control was required. A retrospective electrocardiographic-gated CT angiography examination was performed after the injection of non-ionic iodinated contrast medium (1.0–1.5 ml/kg body weight) via a peripheral intravenous line followed by a saline chaser. A ‘manual’ bolus tracking method was used with a manually triggered acquisition device when optimal contrast opacification within the pulmonary vessels was perceived on the monitoring sequence. Automated tube voltage selection and automated tube current modulation based on body habitus (CARE kV and CARE Dose4D, Siemens Healthineers) were enabled.

Slices were reconstructed with 0.6-mm section thickness and increments of 0.4 mm, using a medium sharp kernel (Bv40), with a model-based iterative reconstruction strength level 3 (ADMIRE; Siemens Healthineers). Multiplanar reformatted images and volume-rendered images including ‘virtual dissection’ images were reconstructed and analysed on an external workstation (Syngo.via, Siemens Healthineers).

RESULTS

Incidence

Due to the rarity of the entity described on the basis of the biatrial connection of the right superior caval vein, its incidence is unknown. The entity is rarely mentioned in contemporary cardiology textbooks. Biatrial drainage is more difficult to evaluate because this finding is a feature of most instances of the superior sinus venosus defect, albeit rarely with the superior caval vein committed primarily to the morphologically left atrium [17]. It was our hypothesis that, although not specified as such by the authors, it is likely that several of the patients previously diagnosed by the original authors as having a biatrial connection of the superior caval vein would now be considered to have sinus venosus defects.

Our literature search revealed 11 case reports of such biatrial drainage without specific mention of its being part of a superior sinus venosus defect [8–14]. Specific reference has been made previously to the association of the finding with the persistent patency of the arterial duct, defects within the oval fossa, divided left atrial chamber and congenital tricuspid stenosis. Associated extracardiac abnormalities include cerebral arterio-venous malformations and hydranencephaly [8–14].

Demographics

The ages of the individuals described as having a biatrial connection of the superior caval vein ranged from 1 day to 74 years, with 4 below 7 years of age [5–14]. The combined association of lesions was more common in women, with a female-to-male ratio of 2 to 1 [5–14]. Among the individuals reported, it was not possible to identify any regional or ethnic predominance. None had the features of the so-called heterotaxy syndromes, now known to reflect isomerism of the atrial appendages (Supplementary Material, Table S1).

Following approval from our institutional ethics committee, we included all 50 consecutive patients falling within our current definition of the sinus venosus septal defects. The individuals were aged from 2 to 60 years [mean ± Standard deviation (SD) 17.6 ± 16.7 years]. All had undergone preoperative scanning and surgical correction between January 2007 and December 2019. We excluded patients with concomitant significant congenital heart diseases other than a coexisting defect within the oval fossa. Of the patients, 41 were males, with 17 (14%) patients younger than 5 years of age and 20 (40%) older than 15 years of age. Associated cardiac lesions in varying combinations were present in 20 patients, specifically persistent patency of the arterial duct in 4, patent oval foramen in 18, defects at the oval fossa in 6 and persistent left superior caval vein in 10. None of the patients had cardiac isomerism. All had normal sequential segmental anatomy. All patients had an anomalous right superior pulmonary venous connection, with left-sided pulmonary veins draining into the left atrium. The pulmonary veins were considered to have high connections if the upper border of their orifice was >2 cm cranial to the superior cavoatrial junction [15, 16]. We considered pulmonary veins to be connected to the superior cavoatrial junction if their orifices were within 5 mm of the junction of the superior caval vein with the right atrium [15, 16]. As we emphasize, it is likely that only 2 of the patients in our cohort are directly comparable to those previously described as having biatrial connection of the superior caval vein.

Diagnosis

All patients with a so-called biatrial connection of the superior caval vein had central cyanosis at presentation. This condition likely reflects the predominant connection of the overriding superior caval vein to the morphologically left atrium. Other presenting symptoms and signs were congestive heart failure, dyspnoea, intractable seizures unresponsive to anticonvulsants, headache due to meningitis and cardiomegaly. Two patients had cerebral arterio-venous malformations that were incompatible with survival, whereas 1 patient had a brain abscess (Supplementary Material, Table S1) [5–14]. These problems with the central nervous system are unlikely to be directly related to the cardiac lesions.

Pulmonary vascularity on the chest roentgenogram was usually normal. Moderate left ventricular enlargement and left ventricular hypertrophy had been noted in some patients. The differential diagnoses of such patients with central cyanosis, reflecting the left atrial connection of the superior caval vein, and in the absence of clinically detectable abnormalities of the cardiovascular system, include a communication from the right pulmonary artery to the left atrium [18, 19], partially or totally anomalous systemic venous connection to left atrium [20–28], congenital pulmonary arterio-venous malformations [29], haemoglobinopathies, methemoglobinemia, pulmonary vascular obstructive disease and Eisenmenger’s syndrome.

In these patients, the diagnosis was made by saline contrast echocardiography, radionuclide angiography, magnetic resonance imaging, computed tomographic angiography, conventional angiocardiography and at autopsy [5–14]. Saline contrast echocardiography is very useful in distinguishing the alternative diagnoses. Contrast visualization of the left atrium, the left ventricle and the aorta without opacification of the right ventricle with injections into the veins of both hands suggests either drainage of the right superior caval vein to the left atrium or persistence of the left superior caval vein with unroofing of the coronary sinus. The injection into the right hand is likely to provide the best arbitration.

Echocardiographic diagnosis alone may be difficult in adult patients due to operator variability and a poor acoustic window. Drainage of the right superior caval vein to the left atrium, in contrast, can be diagnosed with certainty on cardiac magnetic resonance imaging, and on contrast enhanced CT [17, 29–36]. Both these investigative modalities are reliable and non-invasive and are complementary to each other. The advantages of CT, nonetheless, must be weighed against the use of ionizing radiation in children.

If catheterization is undertaken, it may reveal the course of the catheter into the left atrium through the right internal jugular vein and superior caval vein. Selective pulmonary arteriography is helpful in distinguishing communications between the right pulmonary artery and the left atrium or a pulmonary arterio-venous malformation [29].

Our review of the reported anatomical findings in these cases, which are unified by the combination of the biatrial connection of the right superior caval vein and varying degrees of right-sided partially anomalous pulmonary venous connection to the right superior caval vein, shows that all individuals exhibited the lesion we would now describe as the variant of the superior sinus venosus defect with a predominant left atrial connection of the overriding caval vein (Fig. 1).

The inferior caval vein and the coronary sinus were connected normally with the morphologically right atrium in all patients. The eustachian and Thebasian valves were present and well developed. The atrioventricular and ventriculo-arterial connections were normal in all patients. The ventricular and atrioventricular septal structures and the arterial valves were normal. The majority of the patients exhibited hypertrophy and enlargement of both the atria and the left ventricle. All had the usual atrial arrangement, and none had so-called ‘heterotaxy’ syndrome [5–14].

Morphogenesis

Various theories have been proposed to explain the origin of the combination of a partially anomalous pulmonary venous connection in the setting of a biatrial connection of the superior caval vein. Several share the notion that the anomalously connected pulmonary veins have retained their left atrial connection. The explanations flounder, however, when suggesting that the changes reflect the absence of a common wall alleged to be present between the cavities of the right pulmonary veins and the superior caval vein [36–38]. In part, these anatomical interpretations reflect the on-going controversies with regard to whether the developing pulmonary vein takes its origin from the systemic venous sinus or originates directly from the left atrium [39].

The pulmonary veins, of necessity, develop within the lung buds. Although it had been popular to suggest that, when a connection develops between these intraparenchymal pulmonary venous connections and the atrial chambers, it is achieved via the systemic venous sinus, recent findings have shown that the pulmonary veins in the human heart never have a direct connection to the systemic channels [40–44]. Indeed, the pulmonary vein does not canalize in the midline of the pharyngeal mesenchyme until after the systemic venous tributaries have achieved their own connection to the developing right atrium. And, when the pulmonary vein is first identified, at the stage of human development known as Carnegie stage 14, it is a solitary channel that opens to the developing left atrium through the persisting communication between the primary atrial component of the heart tube, known as the dorsal mesocardium.

This connection is achieved prior to the closure of the primary atrial foramen, but at a stage when the boundaries of the systemic venous sinus are marked by the formation of the so-called venous valves. It is not until after the completion of ventricular septation, during Carnegie stages 20–23, that the pulmonary venous component of the left atrium begins to achieve its definitive location on the roof of the left atrium. Only as the pulmonary veins achieve this definitive location does it become possible to recognize the superior interatrial fold, against which the flap valve of the oval fossa, derived from the primary atrial septum, abuts to close the oval foramen.

Until recently, however, this superior interatrial fold has itself been considered to represent a second atrial septum [44]. It is this so-called septum secundum over which the superior caval vein is reputed to override. Because the interatrial fold itself cannot develop until some part of the right-sided pulmonary venous connection has achieved a location that permits drainage to the left atrial roof, and the fold thus formed interposes between the systemic venous sinus and the left atrial wall, it follows that overriding of the superior caval vein relative to the atrial septum cannot adequately be explained on the basis of the abnormal formation of the systemic venous sinus itself.

Collateral channels between the developing individual pulmonary veins and adjacent systemic venous channels, nonetheless, are known to be present throughout normal development [45, 46]. The isolated anomalous connection of individual right pulmonary veins to the superior caval vein is also a well-recognized lesion. The site of such drainage is directly comparable to the site of anomalous drainage seen in the typical sinus venosus defect, although it is now recognized that some superior sinus venosus defects can be found without overriding of the superior caval vein [17]. The logical explanation for the morphogenesis of the superior sinus venosus defect, therefore, is that the anomalously connecting pulmonary veins have retained their initial connection to the left atrium, thus producing an extraseptal venovenous bridge [4, 47, 48].

This explanation for the biatrial connection of the superior caval vein, in fact, was offered some time ago by Shapiro and associates [11]. They postulated that the right upper lobe of the lung made venous connections to both the left atrium and the superior caval vein, stating ‘thus, the connecting channels may be of pulmonary venous origin’ [11]. It was this same concept that was subsequently advanced by Butts and colleagues to explain the superior sinus venosus defect, arguing that the right pulmonary veins were able to connect anomalously to the superior caval vein, while retaining their left atrial communication [4]. A similar concept had been proposed by Crystal et al. [3] to account for the inferior sinus venosus defect.

Surgical approach and management

Of the initial reported cases, only 3 had undergone surgical correction (Supplementary Material, Table S1). The principles of surgical intervention, of course, are the same as those for the superior sinus venosus defect, namely maintenance of an unrestricted pathway for the anomalous pulmonary venous system to the morphologically left atrium, at the same time ensuring a non-restrictive pathway between the superior caval vein and the morphologically right atrium. In this regard, no cases with surgical intervention were reported after 1981. The findings, therefore, are not of great consequence for current management.

The surgical techniques may be categorized into either of the 2 following categories:

• Ligation of the abnormal connection between the right superior caval vein and the left atrium. Laboux and colleagues, in 1968, utilized this technique successfully in a 9-year-old child with biatrial drainage of the right superior caval vein. They ligated the connection to the left atrium, leaving the caval venous blood to flow directly to the right atrium [12].

• Placement of an intra-atrial baffle made of a polytetrafluoroethylene patch between the pulmonary veins and the right superior caval vein with the patient under cardioplegic arrest.

• Enjalbert and associates in 1967 and Shapiro and associates in 1981 described this technique of inserting a baffle between the superior caval vein and the left atrium, thus diverting the pulmonary veins to the left atrium [11, 13]. Shapiro and associates subsequently enlarged the narrowed superior cavoatrial junction using a synthetic patch [13].

Surgery for a superior sinus venosus defect using the double-barrel technique

All our patients with superior sinus venosus defects, irrespective of the precise drainage of the superior caval vein, underwent composite atrial turn-down reconstruction of the superior caval vein, with preservation of the cavoatrial junction and the artery to the sinus node, using moderately hypothermic cardiopulmonary bypass (Fig. 2 and Video 1). The technical details of the procedure have been described in our previous publications [15, 16].

Short- and long-term outcomes

Of the 11 patients previously reported, 7 died without any surgical intervention and 1 patient died 2 years after the operation. The remaining 2 patients survived and were doing well at the time of reporting. Cerebral arterio-venous malformation, diffuse subarachnoid haemorrhage, hydranencephaly, cerebral atrophy, intractable seizures unresponsive to anticonvulsants, brain abscess, congestive heart failure and septicaemia were described as causes of death. In our series, no patients died during the operation or in the early or late postoperative periods (Supplementary Material, Table S1) [5–14].

Among our patients, 17 (34%) had a partially anomalous pulmonary venous connection at the superior cavoatrial junction, whereas 33 (66%) had high anomalous connections (Figs 3 and 4). The angiographically measured transverse dimension of the defects was 20.8 ± 4.4 mm, and the superior-inferior dimension was 18.0 ± 3.8 mm. In 2 (4%) patients, there was significant caudal extension, with the superior-inferior dimension measuring 21 mm. The degree of override of the right superior caval vein across the superior rim of the oval fossa was assessed in all patients both pre- and intraoperatively. In only 2 (4%) patients was there override greater than 50% to the left atrium. It is these individuals, we believe, who can be compared directly with the individuals previously reported as having a biatrial connection of the superior caval vein. In two-thirds of our cohort, the override was up to 50%, whereas the remaining patients lacked any override, with the superior caval vein draining exclusively to the morphologically right atrium (Figs 5–7). The dimensions measured preoperatively were similar to those measured intraoperatively. In 2 (4%) patients, there was mild systemic arterial desaturation ranging between 93% and 96%. At a mean follow-up of 103.9 (±50.2) months, no patient had obstruction of either the systemic or pulmonary venous pathways [16].

DISCUSSION

To the best of our knowledge, it is usually accepted that Ross, in 1956, coined the term sinus venosus defect [1]. As emphasized in our introduction, therefore, it is intriguing to discover that, in 1858, Peacock had described how the hole permitting the interatrial communication as described by Ross was separated from the normal septal structures. Peacock concluded that the interatrial communication was not a defect in the true atrial septum [2]. Rather, it represented the left atrial orifice of the right upper and lower pulmonary veins, which had been ‘unroofed’ into the right superior caval vein or into the right atrium. The notion of ‘unroofing’ has subsequently been supported by Shapiro et al. [10], by Van Praagh et al. [36] and by Butts et al. [4]. In an attempt to provide a logical explanation for these findings, Edwards and Helmholz [45], in 1956, pointed to the persistence of the collateral channels that exist in the developing foetus between the systemic and pulmonary venous systems. Shortly thereafter, in 1957, Swan et al. [46] demonstrated the persistence of extracardiac connections between the pulmonary venous sinus and the primordium of the superior caval vein in the foetus. Such a venovenous collateral channel was also described by Devine and Anderson [47] at autopsy in a solitary case, with the suggestion that this could be ‘forme fruste’ of the sinus venosus defect. The knowledge accrued over the last century and a half, therefore, reveals the transition from venovenous bridges, to a partially anomalous pulmonary venous connection and finally to the sinus venosus defect.

In anatomical terms, the superior sinus venosus defects share 3 basic characteristics. First, they are superior to the oval fossa. Second, being separate from the fossa, they lack complete margins. Third, and perhaps most significantly, they are uniformly associated with anomalous drainage of 1 or more of the right pulmonary veins. The morphological criterion for diagnosis of an ‘atrial septal defect’ is the integrity of the rims of the oval fossa. Such true interatrial communications, of course, can co-exist with the sinus venosus defect. The inferior margin of the superior caval defect, in the setting of the biatrial connection of the superior caval vein, is the cranial rim of the oval fossa. This rim is an invagination of the atrial walls rather than a ‘second’ atrial septum [25, 26]. As was emphasized by Peacock, therefore, the so-called sinus venosus defect is not a deficiency of the true atrial septum. Its anatomical differentiation from anomalous systemic connection to the morphologically left atrium, however, remains enigmatic [2]. The anatomical similarities we have emphasized between examples of the superior sinus venosus defect with predominant left atrial connection of the overriding superior caval vein and the cases described as a biatrial connection of the right superior caval vein, suggest that exclusive connection of the caval vein to the left atrium is no more than the end of the spectrum of overriding (Figs 5–7). This interpretation is supported by the fact that the other end of the spectrum of sinus venosus defects is found when the superior caval vein retains an exclusive connection to the right atrium, yet still in presence of a superior interatrial communication outside the confines of the atrial septum [4, 15–17, 56].

The variations in the anatomy of the cavoatrial junction and the anomalously connected pulmonary veins have now been further clarified by a study of 96 patients from our institution using computed-tomographic angiography [17]. The defects in these individuals measured 19.4 ± 5.4 mm transversely and 18.0 ± 4.9 mm in their superior-inferior extent. Of these patients, 7 had significant caudal extension of the defect. In 67 (70%) patients, the superior caval vein overrode the superior rim of the oval fossa. In only 3 patients was it committed predominantly to the left atrium, with these being the ones directly comparable to the lesion previously described in terms of a biatrial connection of the superior caval vein. In 29 (30%) patients, there was no overriding [17]. The issue of the degree of overriding of the orifice of the superior caval vein across the superior rim of the oval fossa has previously been inadequately addressed, in part because there is no standard method for measuring its extent [2, 36, 50]. Among our patients undergoing surgery, we observed an override of up to 50% in two-thirds, with an override of >50%, as emphasized, in only 2 patients (Figs 5–7).

Significantly, unlike defects within the oval fossa, the sinus venosus defect is not simply a hole. Recognition of this fact has obvious significance for the cardiac surgeon. It is more than a mere discussion of semantics. The superior cavoatrial junction, along with abnormally connected pulmonary veins, creates a cone of space between the mouth of the superior caval vein and the superior rim of the oval fossa [17, 36, 49–55]. The resulting variable override of the caval vein is comparable with the aortic override seen in the setting of tetralogy of Fallot [17]. The left posterior aspect of the cone of space is closed to re-establish unobstructed drainage of the superior caval vein to the right atrium and of the pulmonary veins to the left atrium. Recognition of these features serves to emphasize the goal of any surgical technique, namely, to achieve a wide unrestricted anastomosis, at the same time avoiding injury to the sinus node or its artery. It follows, therefore, that to determine the optimal approach, accurate recognition of the underlying anatomy is essential. It is equally important to begin with an appropriate strategy for venous cannulation [16, 26].

CONCLUSION

Analysis of the published literature suggests that a biatrial connection of the superior caval vein and by extension the overall spectrum of sinus venosus defects is the result of persistent venovenous bridges present in the foetus rather than a problem with atrial septation.

SUPPLEMENTARY MATERIAL

Supplementary material is available at EJCTS online.

STATEMENT OF HUMAN RIGHTS/ETHICAL APPROVAL

The authors assert that all procedures contributing to this study comply with the ethical standards of the relevant national guidelines on human experimentation and with the Declaration of Helsinki 1975, as revised in 2008.

Funding

The authors received no financial support for the research, authorship and/or publication of this article.

Conflict of interest: The author(s) declared no potential conflicts of interest with respect to the research, authorship and/or publication of the article.

Data Availability Statement

Data are available in the Supplementary Material.

Author contributions

Ujjwal Kumar Chowdhury: Conceptualization; Data curation; Formal analysis; Investigation; Methodology; Resources; Supervision; Validation; Visualization; Writing—review & editing. Robert H. Anderson: Conceptualization; Data curation; Formal analysis; Methodology; Resources; Supervision; Validation; Writing—original draft; Writing—review & editing. Niraj Nirmal Pandey: Data curation; Investigation; Resources; Visualization. Srikant Sharma: Investigation; Resources. Lakshmi Kumari Sankhyan: Conceptualization; Data curation; Formal analysis; Investigation; Methodology; Supervision; Writing—review & editing. Niwin George: Resources; Validation; Writing—review & editing. Shikha Goja: Data curation; Investigation; Resources. Balaji Arvind: Investigation; Resources.

Reviewer information

European Journal of Cardio-Thoracic Surgery thanks Mark H. D. Danton, Attilio A. Lotto and the other, anonymous reviewer(s) for their contribution to the peer review process of this article.

LEGEND OF VIDEO PRESENTATION

We present a 9-year-old male diagnosed with superior sinus venosus defect with anomalous drainage of right superior and middle pulmonary veins above the superior cavoatrial junction undergoing Dacron patch closure of the septal defect and reconstruction of the systemic venous pathway using the double-barrel technique with an intact cavoatrial junction.

Surgical techniques

Patient position

• The patient was placed in a supine position.

Intraoperative transoesophageal echocardiography

• Intraoperative transoesophageal echocardiography was performed using a Philips echocardiographic machine to assess the morphology of the septal defect, the degree of override of the superior caval vein across the septal defect and the direction of shunting and to assess the adequacy of the newly reconstructed systemic and pulmonary venous pathway with particular attention to avoidance of any gradient at the superior cavoatrial junction and the pulmonary veins.

Surgical planning

• Following a median sternotomy, the thymus was subtotally excised. The pericardium was incised at the midline using scissors. We did not use any cautery to avoid cautery-induced ventricular fibrillation. The cardiac structures were freed of flimsy adhesions. The brachiocephalic vein was absent, and there were 2 separate right and left superior caval veins.

• Following systemic heparinization, the operation was performed under moderately hypothermic cardiopulmonary bypass (32°C) with an aortic infusion cannula, straight venous cannula into the inferior caval vein and an angled venous cannula into the left superior caval vein. The right superior caval vein was not cannulated because of its smaller size and an anticipated requirement of an extended superior cavotomy because of the high insertion of the pulmonary veins. Antegrade St. Thomas (II)-based cold hyperkalaemic blood cardioplegia and topical ice cooling were used for myocardial preservation.

• The right superior caval vein was dissected using a peanut swab, avoiding injury to the right phrenic nerve and the pulmonary veins. The right superior and right middle pulmonary veins entered about 1 cm above the superior cavoatrial junction. The right atrial appendage was left untouched.

Separate cavotomy and atriotomy incisions

• Two separate atriotomy and cavotomy incisions were made between the stay sutures 1 cm above and below the cavoatrial junction, thus avoiding injury to the sinoatrial nodal artery and the sinus node. The length and breadth of the sinus venosus defect were measured inside the cava from the margin of the sinus venosus defect to the distal-most pulmonary venous ostium.

• The width of the sinus venosus defect was measured superiorly and inferiorly at 2 points to avoid excessive tightening or redundancy.

Dacron patch closure of the sinus venosus defect

• An appropriately sized, slightly dome-shaped baffle of Dacron patch material (BARD SAUVAGE Filamentous Knitted Polyester Fabric, M/s Peripheral Vascular Inc., Tempe, AZ, USA) was selected for the intracaval pulmonary venous baffle. The patch was sutured into the defect using 5–0 polypropylene suture (Johnson and Johnson Ltd., Ethicon, LLC, San Lorenzo, CA, USA) around the margin of the sinus venosus defect and above the ostia of the pulmonary veins, avoiding too deep stitches or wrong tailoring and possible pulling, which might endanger the critical sinoatrial nodal artery. The pulmonary venous tunnel patch was sutured using a double-armed 5–0 polypropylene suture in a continuous manner with the margin of the septal defect and as a horizontal mattress suture above the pulmonary veins and the sinoatrial nodal arterial territory, avoiding excessive pulling and narrowing. Utmost precautions were taken while sizing the patch to avoid redundancy or flattening/narrowing of the pulmonary veins.

Reconstruction of the systemic venous pathway

• The tip of the right atrial appendage was incised at the crest with complete excision of all trabeculations within the appendage enhancing its expandability and reducing the chances of subsequent stenosis and thrombus formation. The systemic venous pathway was reconstructed by atriocavoplasty, using the adjacent right atrial crest to the superior cavotomy as an onlay patch in the form of a double barrel, preserving the cavoatrial junction. Suturing starts from the lower end of the appendage atriotomy to the corresponding margin of the cavotomy using 5–0 polypropylene suture. The superior cavoatrial junction was kept intact, and a complete tension-free cavoatrial anastomosis was performed without any pericardium or synthetic patches.

Postoperatively, the child was in normal sinus rhythm, and recovery was uneventful. At the 12-month follow-up, the child was asymptomatic, in normal sinus rhythm with no echocardiographic evidence of systemic and pulmonary venous pathway obstruction.

REFERENCES

ABBREVIATION

 
• CT

  Computed tomography

Author notes