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C O L L E G E O F C A R D I O L O G Y F O U N DA T I O N . T H I S I S A N O P E N A C C E S S A R T I C L E U N D E R

T H E C C B Y - N C - N D L I C E N S E ( h t t p : / / c r e a t i v e c o mm o n s . o r g / l i c e n s e s / b y - n c - n d / 4 . 0 / ) .

CONGENITAL MINI-FOCUS ISSUE

CASE REPORT: CLINICAL CASE

Senning Procedure for Physiological

Atrial Inversion With Left Atrial IsomerismBibhuti B. Das, MD,a K. Anitha Jayakumar, MD,b Ming-Lon Young, MD,b Kak-Chen Chan, MDb

ABSTRACT

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We present the case of an infant with left atrial isomerism with complex pulmonary and systemic venous connections

that resulted in physiological parallel circulation in the setting of ventriculoarterial concordance who was surgically

treated using the Senning procedure. This case highlights a rare cause for cyanosis due to poor mixing from a parallel

circulation and an issue with nomenclature. (Level of Difficulty: Advanced.)

(J Am Coll Cardiol Case Rep 2019;1:516–22) © 2019 The Authors. Published by Elsevier on behalf of the

American College of Cardiology Foundation. This is an open access article under the CC BY-NC-ND license

(http://creativecommons.org/licenses/by-nc-nd/4.0/).

HISTORY OF PRESENTATION

A baby boy was emergently delivered by cesareansection at 35 weeks of gestation secondary to persis-tent fetal bradycardia to a 29-year-old, gravida 2 para2 mother. Birth weight was 2.1 kg, and Apgar scoreswere 4, 6, and 8 at 1, 5, and 10 min, respectively.Pregnancy was complicated by gestational diabetesand urinary tract infection, but there was no familyhistory or a prior fetal diagnosis of congenital heartdisease. The infant was intubated immediately after

EARNING OBJECTIVES

Multimodality imaging, including chestradiography, echocardiography, angiog-raphy, and computed tomographic angiog-raphy, is critical to define the segmentalanatomy precisely in heterotaxy syndrome.Venoatrial connection abnormalities canhave a profound impact on clinical presen-tation and management.The Senning procedure can be successfullyperformed in isolated physiological atrialinversion with LA isomerism.

N 2666-0849

m the aDepartment of Pediatric Cardiology, Baylor College of Medicine

stin, Texas; and the bJoe DiMaggio Children’s Hospital Heart Institute, M

thors have reported that they have no relationships relevant to the conte

ormed consent was obtained for this case.

nuscript received June 20, 2019; revised manuscript received October 2,

birth for cyanosis and respiratory distress. His phys-ical examination at birth was notable for severebradycardia (heart rate 50 to 60 beats/min), cyanosis(oxygen saturation 70%), and no appreciable mur-murs. Breath sounds were diminished in both lungfields. Examination of other systems were reportedlyunremarkable.

DIFFERENTIAL DIAGNOSIS

The complex anatomy of the present case is shown inFigure 1. The initial differential diagnosis includedpersistent pulmonary hypertension of the newborn,respiratory distress syndrome secondary to prematu-rity, congenital diaphragmatic hernia (CDH), andcyanotic congenital heart disease such as completetransposition of the great arteries (TGA) and obstruc-ted total anomalous pulmonary venous return.

INVESTIGATIONS AND MANAGEMENT

Chest radiography was diagnostic for a right CDH withthe intestinal contents in the right side of thechest, with complete opacification of the left lung(Figure 2). Electrocardiography demonstrated

https://doi.org/10.1016/j.jaccas.2019.11.001

, Texas Children’s Hospital, Austin Specialty Care,

emorial Healthcare System, Hollywood, Florida. The

nts of this paper to disclose.

2019, accepted November 3, 2019.

FIGURE 1 Schematic Diagram of the Complex Anatomy

AO ¼ aorta; conf ¼ confluence; HV ¼ hepatic vein;

IVC ¼ inferior vena cava; LAA ¼ left atrial appendage;

PA ¼ pulmonary artery; PV ¼ pulmonary vein; RV ¼ right

ventricle; SVC ¼ superior vena cava.

AB BR E V I A T I O N S

AND ACRONYM S

CDH = congenital

diaphragmatic hernia

SVC = superior vena cava

LA = left atrial

TGA = transposition of the

great arteries

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junctional bradycardia and a markedly prolongedcorrected QT interval of 600 ms (Figure 3). Echocar-diography showed a midline liver, levocardia,possible bilateral left atrial (LA) appendages, unob-structed total anomalous pulmonary venous drainageto the right-sided morphological left atrium, theentire systemic venous drainage through a left-sidedsuperior vena cava (SVC) and an uninterrupted infe-rior vena cava, both of which coursed to the left of thespine (Figure 4) before draining directly into the left-sided morphological left atrium. The left-sided sys-temic venous atrium connected to a left-sidedmorphological left ventricle (d-loop ventricularmass), and the right-sided pulmonary venous atriumconnected to a right-sided morphological rightventricle, resulting in parallel circulation. The ven-triculoarterial connections were concordant, and thegreat arteries were normally related. In addition,there was a small patent foramen ovale with bidi-rectional shunting, an intact ventricular septum, anda large ductus arteriosus with predominantly left-to-right shunting. Isomerism of the LA appendages wassuspected with complex segmental anatomy. Thesequential segmental anatomy would be LA isom-erism, ambiguous biventricular atrioventricularconnection with d-looping, and ventriculoarterialconcordance and would seem most consistent with{A, D, S}. Computed tomographic angiographyconfirmed the anatomy, including the venous con-nections to the atria, morphologically bilateral LAappendages (Figure 5), and bilateral morphologicalleft bronchi (Figure 6). Additional findings includedleft ventricular noncompaction (Figure 7), but biven-tricular systolic function was normal.

MEDICAL HISTORY AND MANAGEMENT

BEFORE SENNING

The infant had severe persistent cyanosis after birththat was attributed to CDH, associated pulmonaryhypertension of the newborn, and parallel circulationbecause of the abnormally discordant systemic andpulmonary venous drainage. An urgent balloon atrialseptostomy was performed, and he underwent suc-cessful surgical repair of the CDH on day 2 of life.While recuperating from CDH surgery, cyanosis per-sisted, and a 3.5-mm central aortopulmonary shuntwas placed and the ductus arteriosus was ligated at1 week of age. Following surgical shunt placement,the infant initially had persistent cyanosis, but chestradiography showed prominent pulmonary vascularmarkings. Cardiac catheterization was performed thataffirmed the previously described anatomy, includingespecially the systemic venous drainage anatomy

with a left-sided SVC and the hepatic veinsthat joined the uninterrupted inferior venacava before draining directly into the left-sided atrium (Figure 8). Hemodynamic sta-tus at cardiac catheterization was as follows:mean right atrial pressure 11 mm Hg, pulmo-nary artery pressure 43/26 mm Hg (mean25 mm Hg), pulmonary blood flow 7.35 l/min/m2,systemic blood flow 3.13 l/min/m2, and pulmo-

nary blood flow/systemic blood flow ratio 2.35:1, and yethis systemic saturation was only 76%, consistent withthe predicted parallel circulatory physiology.

SURGICAL PROCEDURE (SENNING)

At 3.5 months of age, the infant underwent amodified Senning procedure, take-down of thecentral shunt, and placement of an epicardial dual-chamber pacemaker. In this case, the systemic andpulmonary venous return was “transposed,”resulting in “physiological atrial inversion” andcreating a circulatory pattern resembling classicald-TGA. The rationale for the Senning procedure wasto create a physiologically normal series circulationby redirecting the systemic and pulmonary venous

FIGURE 2 Chest Radiograph at Birth Showing Right-Sided

Congenital Diaphragmatic Hernia

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return to the appropriate ventricles using intra-atrial baffles, and the left ventricle remained as asystemic ventricle (1).

EXTRACARDIAC FINDINGS

The infant’s chromosomal microarray was negativefor long-QT syndrome but was positive for a mutation(c.663T>A, p.Tyr221) in the DSC2 gene, which hasbeen associated with arrhythmogenic right ventricu-lar cardiomyopathy but not reported with LA isom-erism. The infant also had the following extracardiacanomalies: intestinal malrotation, bilateral inguinalhernias, a dual collecting system and right-sidedhydronephrosis, nephrolithiasis, and multisuturalcraniosynostosis. He underwent multiple noncardiacprocedures, including a tracheostomy for ventilatordependency, Ladd’s procedure, herniorrhaphy, Nis-sen fundoplication, gastrostomy tube placement, andopen cranial vault remodeling surgery for craniosy-nostosis. He was discharged from the hospital at4.5 months of age.

FOLLOW-UP

The infant’s tracheostomy was successfully dec-annulated at 18 months of age. Despite his complex

multisystem issues, he has been clinically doing welland thriving. Echocardiography at 32 months of ageshowed no obstruction of the intra-atrial systemic orpulmonary venous baffles (Figure 9), normal biven-tricular systolic function, and minimal atrioventric-ular regurgitation, without evidence of pulmonaryhypertension.

DISCUSSION

Heterotaxy syndrome is defined as an abnormality oflaterality in which the thoracoabdominal organsdemonstrate abnormal arrangement across the left-right axis of the body (2). The morphology of theatria and in particular the atrial appendages oftenallow determination of “sidedness.” This can bedetermined by echocardiography, but sometimesother imaging modalities such as angiography andcomputed tomographic angiography are essential fordiagnosis, as they also allow clearer delineation of thearrangement of thoracoabdominal organs. LA isom-erism or bilateral left-sidedness refers to duplicationof the left-sided structures with features such asbilateral LA appendages, persistent left SVC, pulmo-nary veins connecting bilaterally to the atria (60%),interruption of the inferior vena cava, and additionalcomplex intracardiac defects (3). Right atrial isom-erism or bilateral right-sidedness can be associatedwith bilateral SVC, TGA, pulmonary artery stenosis oratresia, and an atrioventricular septal defect. Evalu-ation of the heart in patients with heterotaxy syn-drome requires a complete description of both atrialappendages and the venoatrial, atrioventricular,and ventriculoarterial connections of the cardiacsegments.

In our patient, physiologically discordant atrio-ventricular connections due to pulmonary venousdrainage were to the right-sided morphological leftatrium and systemic venous drainage to the left-sidedmorphological left atrium, but concordant ven-triculoarterial connections constituted a circulationthat resembled classical d-TGA (Figure 1). This casedemonstrates the complexity of ascribing a nomen-clature label to a rare complex abnormal connection,be it descriptive or numeric. The old adage ofdescribing the morphological structures as it existsholds true. In this case, it predicts the true hemody-namic physiology of a parallel circulation without theusual ventriculoarterial discordance. According tomorphological description, this patient had trans-posed systemic and pulmonary veins, resulting in aparallel circulation akin to d-TGA. Its morphologicalname is as yet undescribed, and perhaps it can be bestdescribed as physiological venoatrial discordance in

FIGURE 3 Electrocardiogram on Second Day of Life

Junctional bradycardia (heart rate 60 beats/min), with a prolonged corrected QT interval of 600 ms with a long ST-segment.

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the setting of LA isomerism and ventriculoarterialconcordance {A, D, S}. This rare condition is differentfrom isolated atrial and ventricular inversion ac-cording to strict anatomic segmental descriptions butcan be physiologically similar (4–8). An atrial switchoperation such as the Senning procedure achieves

FIGURE 4 Subcostal Short-Axis Echocardiographic Findings

Showing the relationship of IVC, which is Anterior and Left

to the AO

AO ¼ aorta; IVC ¼ inferior vena cava.

physiological correction by redirecting the pulmo-nary venous return into the systemic left ventricleand the systemic venous return into the sub-pulmonary right ventricle, as has been previouslydescribed (3–7).

FIGURE 5 CTA Confirming Connection of Pulmonary Venous

Confluence to a Right-Sided Atrium With a Morphological

LAA

CTA ¼ computed tomographic angiography; LAA ¼ left atrial

appendage; PV ¼ pulmonary vein; RV ¼ right ventricle.

FIGURE 6 CTA Confirming the Bilateral Morphological Left

Bronchi

FIGURE 8 Atrial Angiogram Demonstrating the Connection

of Systemic Veins to the Left-Sided Atrium With a

Morphological LAA

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Junctional bradycardia due to a hypoplastic or ab-sent sinus node, which is a right atrial structure, hasalso been well described in LA isomerism. In 30% ofpatients with LA isomerism, there are twin atrioven-tricular nodes, and pacing is required in 12% of pa-tients (9). However, the association between long-QT

FIGURE 7 4-Chamber Echocardiographic View Showing

Noncompaction of the Left Ventricle

Pulmonary venous (PV) confluence (conf.) is connected to the

right-sided atrium.

HV ¼ hepatic vein; IVC ¼ inferior vena cava; LAA ¼ left atrial

appendage; SVC ¼ superior vena cava.

syndrome and heterotaxy syndrome has not beendescribed. Genetic testing for long-QT syndrome wasnegative in our patient, but he had an abnormal mu-tation in DSC2 that is commonly associated witharrhythmogenic right ventricular cardiomyopathy. Inlong-term follow-up of atrial switch patients, signifi-cant atrial arrhythmias are described in about 20%(10), as are baffle obstruction or leakage, atrioven-tricular valve regurgitation, and ventriculardysfunction. Left ventricular noncompaction, notedin our patient, also has an increased prevalenceamong patients with heterotaxy syndrome (LA isom-erism) compared with the general population (11).

Our patient remains at higher risk for chronic pul-monary disease and other related comorbidities notonly secondary to CDH but also related to ciliarydysfunction associated with heterotaxy syndrome(12). Patients with LA isomerism exhibit a widespectrum of anomalies involving the thor-acoabdominal viscera, as was seen in our patient. Onthe basis of autopsy series of LA isomerism, intestinalmalrotation is described in about 60.4% of patients(13). Our patient required Ladd’s procedure because

FIGURE 9 Echocardiogram Demonstrating no Obstruction to Systemic or Pulmonary Intra-Atrial Baffle After Senning Procedure

LV ¼ left ventricle; PB ¼ pulmonary intra-atrial baffle; RV ¼ right ventricle; SB ¼ systemic intra-atrial baffle.

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of the same, and a feeding gastrostomy tube wasplaced simultaneously. Urogenital anomalies havebeen reported in 6% of patients with LA isomerism(13), and the duplicated right kidney, hydronephrosisand nephrolithiasis, will continue to require longterm follow up. The complexity of the diagnosishence warrants a multi-disciplinary approach to care,to enhance outcomes and quality of life for thesepatients.

CONCLUSIONS

This exceedingly rare case demonstrates thecomplexity of multisystem anomalies that can pre-sent in a critically ill newborn. It also emphasizes acardiac segmental nomenclature nightmare in com-plex congenital heart diseases and highlights theimportance of meticulous, multimodal evaluation toaccurately diagnose the condition and to optimize

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management. Since the advent of the arterial switchoperation for d-TGA, the role for an atrial switchoperation such as a Senning or Mustard procedure hassignificantly diminished. However, as this case illus-trates, there is still a role for the atrial switch opera-tion outside of the more familiar diagnoses.

ADDRESS FOR CORRESPONDENCE: Dr. Bibhuti B.Das, Department of Pediatric Cardiology, Baylor Col-lege of Medicine, Texas Children’s Hospital, AustinSpecialty Care, Austin, Texas 78759. E-mail: bdas99@hotmail.com.

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8. Clarkson PM, Brandt PW, Barratt-Boyes BG,Neutze JM. Isolated atrial inversion. Visceral situssolitus, visceroatrial discordance, discordant ven-tricular d-loop without transposition, dextro-cardia: diagnosis and surgical correction. Am JCardiol 1972;29:877–81.

9. Gilljam T, McCrindle BW, Smallhorn JF, et al.Outcomes of left atrial isomerism over a 28-yearperiod at a single institution. J Am Coll Cardiol2000;36:908–16.

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congenital diaphragmatic hernia: a populationbased study. Ann Thorac Surg 2003;75:250–6.

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12. Flinn CJ, Wolff GS, Dick M, et al. Cardiacrhythm after the Mustard operation for completetransposition of the great arteries. N Engl J Med1984;310:1635–8.

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KEY WORDS atrial inversion, left atrialisomerism, left ventricular noncompaction,Senning procedure