SUPPLEMENTAL MATERIALS

I. Supplemental Methods

Data Collection

Data collection included demographics, sex, race/ethnicity, cardiac and non-cardiac diagnoses,

cardiac and non-cardiac surgeries, morbidities (including infections, thrombosis, intestinal

perforation or volvulus and neurovascular complications), and mortality or need for transplant.

Descriptions of heart anatomy and morphology, cardiac function, bronchial pattern, and

positioning of the liver and spleen were collected from the following: records of chest X-ray

(CXR), echocardiography, cardiac catheterization with angiography, chest CT, cardiac MRI,

surgical reports and necropsy. Systemic ventricular function was assessed primarily by

echocardiography. For echocardiograms, the systemic ventricular function was designated from

the clinical report; any dysfunction (including mild, moderate, or severe) was characterized as

abnormal for this study. Undocumented arrhythmias reported in the clinical record were included

if they were treated.

Medical records including narrative history, ECGs, Holter monitors, exercise testing and

inpatient telemetry, electrophysiological studies, operative notes, and interrogations from

pacemakers (PMs) and implantable cardioverter defibrillators (ICDs) were reviewed for

documented arrhythmias.

Heterotaxy Classification

Heterotaxy cases were classified as right atrial isomerism (RAI) subtype, (also known as

asplenia syndrome) or left atrial isomerism (LAI) subtype (also known as polysplenia

syndrome).1 Classification schemes were adapted from prior publications.2-5 RAI and LAI

assignments were primarily based on atrial morphology, bronchial and/or lung anatomy. When

these indicators were unavailable or unclear, RAI was considered probable if ≥2 features typical

of RAI were present. These included abdominal juxtaposition of the aorta and inferior vena

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cava, asplenia and total anomalous pulmonary venous return (TAPVR). Characteristics used for

LAI classification included polysplenia, interruption of the inferior vena cava with azygos vein

continuation, and biliary atresia. LAI was considered probable if at least one of these features, in

addition to structural heart disease, was present. Although malformations associated with HS

may cluster and fall into either the RAI or LAI subtypes they can also overlap and defy

classification schemes.6,7 As such, patients with indeterminate atrial morphology or overlapping

RAI and LAI features were considered to have indeterminate/mixed type atrial isomerism.

Arrhythmia Classification

Clinically significant tachyarrhythmias were defined as: 1) hemodynamically significant or

requiring treatment with pharmacologic agents, temporary pacing wires (TPWs) or electrical

cardioversion/defibrillation; 2) nonsustained (≥ 3 beats, <30-s duration) or sustained (≥30-s

duration) ventricular tachycardia (VT) and 3) sustained (≥30-s duration) supraventricular

tachycardia (SVT). SVT was further categorized into ectopic atrial tachycardia (EAT), atrial

flutter and/or fibrillation (AFF), junctional tachycardia (JT), re-entrant SVT and SVT not

otherwise specified (NOS) when the distinction between EAT and re-entrant SVT could not be

made.

Tachyarrhythmia substrate definitions were adapted from prior publications.8,9

Recognizing that HS patients often have ≥1 baseline primary atrial rhythm with P wave

morphologies different from classic sinus, a diagnosis of EAT was made if there was an acute

change in P wave morphology during tachycardia at a rate ≥20% faster than the preceding

rate.8 Other supportive diagnostic features included varying tachycardia cycle length and

persistent atrial tachycardia in the setting of atrioventricular (AV) block following vagal

maneuvers or adenosine, as well as a P wave morphology in tachycardia different from those

documented on pre-existing 12-lead ECGs. JT was defined as tachycardia originating from the

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atrioventricular junction at a rate >95th percentile of heart rate for age; junctional rates ≤95th

percentile were reported as accelerated junctional rhythm (AJR).9

Additional rhythm disturbances noted, regardless of whether or not there was a history of

SVT included 1) ventricular pre-excitation on ECG (Wolff-Parkinson-White syndrome [WPW])

and 2) the presence of twin AV nodes (AVNs) characterized by two discrete QRS morphologies

without ventricular pre-excitation during sinus or baseline atrial rhythm on ECG or Holter

monitoring.

II. Supplemental Results

Automatic Tachycardias: Junctional Tachycardia

Of the 21 occurrences of junctional arrhythmias, nearly all (90%) occurred in the immediate

postoperative setting: 3 Blalock Taussig Shunts (BTS), 10 Fontans, 4 bidirectional Glenns

(BDGs), and 2 Rastellis. Management included cooling, sedation, atrial overdrive pacing

(n=10), and antiarrhythmic medications (n=11), including amiodarone, procainamide, or beta

anti-adrenergic blocker. At last follow-up encounter, only one of the perioperative cases

continued to have breakthrough JT as an outpatient and underwent an epicardial PM in

conjunction with amiodarone therapy for rhythm control. Notably, all but two patients with JT

had single ventricle substrates. The only anatomical factor associated with JT by univariate

analysis was ≥ moderate atrioventricular valve regurgitation (AVVR) (HR 4.28, 95% CI 1.72-

10.62, Online Supplemental Table S3).

Re-entrant supraventricular tachycardias

Twenty-four patients had a typical re-entrant SVT, 14 of whom underwent an electrophysiology

study (EPS): 4 had an accessory pathway (AP) mediated tachycardia, 2 had AV node re-entry

through a single AV node, 7 had AV node re-entry utilizing two AV nodes and 1 had His re-

entry. In only half of these patients was ablation successful without recurrence. Among the

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remaining 10 patients who did not have an EPS, 2 had ECG findings at baseline and during

SVT consistent with twin AVNs. The only anatomical factor associated with re-entry SVT by

univariate analysis was functional single ventricle (SV) physiology (HR 7.55, 95% CI 1.02-56.03,

Online Supplemental Table 3).

Twenty-five patients had AFF at a median age of 15 (IQR 6, 16) years. After excluding 4

AFF cases that occurred in infants < 1 year, the median age of onset shifted to 19 (IQR 8, 29)

years. Among all AFF patients, 80% had SV anatomy. Echo data available on 18 of 25 patients

at the time of AFF occurrence demonstrated normal ventricular function in 10. While 6 patients

had AFF in the perioperative setting, 75% presented with symptoms as outpatients at a median

age of 20 (IQR 10, 27) years. Half of those with AFF underwent PM implantation (including 2

ICDs for concomitant VT): 2 for sinus node dysfunction and symptomatic bradycardia preceding

onset of AFF, 9 as part of their antiarrhythmia management (either for symptomatic bradycardia

or to allow uptitration of antiarrhythmics), and one for neonatal complete AV block.. Three

patients had MAZE procedures performed. A majority of patients (n=20) were on an

antiarrhythmic at last follow-up. On univariate analysis, AFF was associated with ≥ moderate

AVVR (Table 4, HR 2.94, 95% CI 1.27-6.80).

SVT NOS

Seventeen patients had SVTs of undetermined etiology; a majority (n = 10) occurred in the

postoperative setting, 4 as outpatients following BDG (n=3) or Fontan (n=1), and 3 prior to any

surgery. Two patients, including one who had ECG findings consistent with twin AVNs,

underwent EPS prior to their Fontan palliation. Neither had inducible SVT during their EPS, nor

evidence of an AP; ablations were not attempted. At last follow-up, 11 of 17 were on an

antiarrhythmic.

Ventricular arrhythmias

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Ventricular arrhythmias occurred in 23 patients at a median age of 3 years (IQR 2 mo-16 yrs): 1

had a post-operative ventricular fibrillation (VF) arrest, 5 had sustained VT and 17 had NSVT.

Except for one, all sustained VT and VF episodes occurred in the perioperative setting among

SV patients. Among the 4 SV patients with sustained VT, the 2 with severe ventricular

dysfunction prior to surgery had poorer outcomes – 1 death, 1 transplant – than the 2 with

normal preoperative function. The latter were successfully weaned off antiarrhythmics without

subsequent VT recurrence. The remaining patient with sustained VT had a Rastelli repair prior

to VT onset. With an ICD and medical therapy, his VT is partially controlled; his ICD discharges

appropriate shocks infrequently.

The majority (14/17) of patients with NSVT had single ventricles. Among these, two

thirds (9/14) of cases were detected via routine Holter surveillance in the outpatient setting and

70% (n=10) of cases had normal ventricular function at the time of detection. Function at time

of detection, however, did not appear to correlate with overall outcomes; 40% (n=4) of those

with normal function later died or underwent transplant compared with 50% (n=2) of those with

ventricular dysfunction. In contrast, no patients with biventricular repairs and NSVT died. By

univariate analysis, there were no significant anatomical factors associated with VT (Table 4).

EPS with programmed ventricular stimulation was performed in 3 patients with single

ventricles and NSVT: 1 patient had inducible VT and underwent ICD implantation; the other 2

did not have inducible VT and remain on antiarrhythmic therapy.

Atrioventricular block

Characteristics of 22 patients with AV block, including 3 patients with acquired surgical AV block

are described in Online Supplemental Table S4. The majority (67%) with congenital complete

atrioventricular block (CCAVB) were prenatally diagnosed; the remaining 5 were diagnosed at

birth. Four patients had progressive hydrops prompting delivery, two of which were pre-term.

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Both premature infants (30 and 34 weeks) died shortly after delivery. All but one of the

remaining 13 patients had PMs successfully implanted within the first month of life (the

exception was a relatively asymptomatic patient with CCAVB, asplenia syndrome, s/p VSD

repair in infancy who was referred at age 3 for progressive bradycardia and PM implantation).

Of the 4 patients with high grade AVB, 2 were diagnosed at birth with intermittent

complete AVB and had pacemakers implanted by 2 weeks of age. The other two patients

developed conduction disease after surgical palliations: one between the Glenn and Fontan

palliations, and the other after palliation (i.e. BTS) for duct dependent pulmonary circulation.

III. Supplemental Discussion

In this review of 337 patients with heterotaxy syndrome (HS), more than half (51%) were

Hispanic. Compared to the demographic composition of inpatient admissions with congenital

heart disease at our center (Hispanic 36%, Non-Hispanic White 36%, Non-Hispanic Black 14%,

Other 14%),10 there was an increased representation by Hispanics in our heterotaxy cohort. This

finding echoes those from a recent population-based epidemiologic study on HS in Texas by

Lopez et al.11 Utilizing Texas Birth Defects Registry data from 1999—2006, Lopez et al found an

increased prevalence of HS in Hispanics (57.5% of their cohort). The increased incidence of

heterotaxy among Hispanic infants has also been reported in other national12 and regional

studies (in New York13 and Nevada14). This Hispanic predominance in heterotaxy patients

suggests that the interaction between environmental and genetic variants plays an important

role in HS.

IV. Supplemental References

1. Van Praagh, S. Cardiac Malpositions and the Heterotaxy Syndromes in Keane JF, Lock JE, Fyler DC. ed., Nadas' Pediatric Cardiology 2006. W B Saunders Company; 2006; p.675–697

2. Lim HG, Bacha EA, Marx GR, Marshall A, Fynn-Thompson F, Mayer JE, Del Nido P, Pigula FA: Biventricular repair in patients with heterotaxy syndrome. The Journal of Thoracic and Cardiovascular Surgery 2009; 137:371–379.e373.

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3. Hashmi A, Abu-Sulaiman R, McCrindle BW, Smallhorn JF, Williams WG, Freedom RM: Management and outcomes of right atrial isomerism: a 26-year experience. Journal of the American College of Cardiology 1998; 31:1120–1126.

4. Gilljam T, McCrindle BW, Smallhorn JF, Williams WG, Freedom RM: Outcomes of left atrial isomerism over a 28-year period at a single institution. Journal of the American College of Cardiology 2000; 36:908–916.

5. Lim JSL, McCrindle BW, Smallhorn JF, Golding F, Caldarone CA, Taketazu M, Jaeggi ET: Clinical features, management, and outcome of children with fetal and postnatal diagnoses of isomerism syndromes. Circulation Lippincott Williams & Wilkins, 2005; 112:2454–2461.

6. Van Praagh R, Van Praagh S: Atrial isomerism in the heterotaxy syndromes with asplenia, or polysplenia, or normally formed spleen: an erroneous concept. AJC 1990; 66:1504–1506.

7. Anderson C, Devine WA, Anderson RH, Debich DE, Zuberbuhler JR: Abnormalities of the spleen in relation to congenital malformations of the heart: a survey of necropsy findings in children. Br Heart J 1990; 63:122–128.

8. Shamszad P, Cabrera AG, Kim JJ, Moffett BS, Graves DE, Heinle JS, Rossano JW: Perioperative atrial tachycardia is associated with increased mortality in infants undergoing cardiac surgery. The Journal of Thoracic and Cardiovascular Surgery The American Association for Thoracic Surgery, 2012; 144:396–401.

9. Collins KK, Van Hare GF, Kertesz NJ, et al.: Pediatric Nonpost-Operative Junctional Ectopic Tachycardia. Journal of the American College of Cardiology American College of Cardiology Foundation, 2009; 53:690–697.

10. Texas Inpatient Public Use Data File, 1999-2012. https://www.dshs.texas.gov/thcic/hospitals/Inpatientpudf.shtm

11. Lopez KN, Marengo LK, Canfield MA, Belmont JW, Dickerson HA: Racial disparities in heterotaxy syndrome. Kirby R, Browne M, eds: Birth Defects Research Part A: Clinical and Molecular Teratology 2015; 103:941–950.

12. Lin AE, Ticho BS, Houde K, Westgate M-N, Holmes LB: Heterotaxy: Associated conditions and hospital-based prevalence in newborns. Genetics in Medicine Nature Publishing Group, 2000; 2:157–172.

13. Rigler SL, Kay DM, Sicko RJ, Fan R, Liu A, Caggana M, Browne ML, Druschel CM, Romitti PA, Brody LC, Mills JL: Novel copy-number variants in a population-based investigation of classic heterotaxy. Genetics in Medicine 2014; 17:348–357.

14. Evans WN, Acherman RJ, Restrepo H: Heterotaxy in Southern Nevada: Prenatal Detection and Epidemiology. Pediatr Cardiol Springer US, 2015; 1–5.

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V. Supplemental Figures

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Number of Tachyarrhythmias

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Figure S1. Number of Tachyarrhythmias in Patients with Heterotaxy Syndrome

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VI. Supplemental Tables

Table S1. Patient characteristics and arrhythmia occurrence

All No Arrhythmia Arrhythmia P valuen=337 n=208 n=129

CharacteristicsMale 178 (53%) 115 (55%) 63 (49%) 0.08Race/Ethnicity Hispanic NH White NH Black Other

171 (51%)106 (31%)37 (11%)23 (7%)

114 (55%)62 (30%)19 (9%)13 (4%)

57 (44%)44 (34%)18 (14%)10 (8%)

0.47

Age at HS Presentation Fetus Neonate Childhood Unknown

117 (35%)163 (48%)

24 (7%)33 (10%)

62 (30%)107 (51%)

19 (9%)20 (10%)

55 (43%)56 (43%)

5 (4%)13 (10%)

< 0.001

Biventricular anatomy 109 (32%) 68 (32%) 41 (32%) 0.73Single ventricle anatomy Single RV Single LV Undetermined SV

228 (68%)160 (47%)50 (15%)18 (5%)

140 (67%)98 (47%)34 (16%)

8 (4%)

88 (68%)62 (48%)16 (12%)10 (8%)

0.68

Isomerism TypeRAILAIUndetermined

130 (39%)121 (36%)86 (25%)

84 (40%)68 (33%)56 (27%)

46 (36%)53 (41%)30 (23%)

0.41

Pulmonary venous obstruction 77 (23%) 46 (22%) 31 (24%)

0.009

Pulmonary Venous ConnectionsPartial AnomalousTotal AnomalousNormal

52 (50%)169 (16%)116 (34%)

31 (15%)99 (48%)78 (37%)

21 (16%)70 (54%)38 (30%)

0.19

Ventricular Outflow TractsPulmonary ObstructionAortic ObstructionAortic and Pulmonary ObstructionNo Obstruction

228 (68%)39 (12%)

8 (2%)

62 (18%)

139 (67%)28 (13%)

2 (1%)

39 (19%)

89 (69%)11 (8%)6 (5%)

23 (18%)

0.02

Age at last follow-up (IQR)

7 y(2 y, 13 y)

6 y(1 y, 12 y)

9 y(4 y, 16 y)

0.07

Age at last follow-up reported as median. Relationship between age at last follow-up and arrhythmia occurrence analyzed by Independent Samples Median Test. All other analyses performed using time to event (arrhythmia) analysis; p values calculated by Cox regression.NH indicates Non-Hispanic; HS, Heterotaxy syndrome, LV, left ventricle; RV, right ventricle; RAI, right atrial isomerism, LAI, left atrial isomerism; IQR, interquartile range (25th percentile, 75th percentile); d, days; m, months; and y, years.

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Table S2. Characteristics and Onset Of Tachycardia By Type

EAT Atrial Fibrillation

Atrial Flutter

Re-entrant SVT

SVT NOS Junctional Ventricular

38 25 23 17 21 23CharacteristicMale 20 (53%) 13 (52%) 14 (61%) 9 (53%) 8 (38%) 10 (43%)Median age at onset(IQR)

3.5 m(13 d, 6 y)

15 y(6 y, 26 y)

22 m(2 m, 9 y)

8 m(9 d, 5 y)

3 y(11 m, 6 y)

3 y(2 m, 16 y)

Arrhythmia OnsetPerioperative 25 (65%) 6 (24%) 8 (35%) 10 (59%) 19 (81%) 8 (34%)Inpt hospitalization 1 (3) 0 1 (4) 0 0Outpatient 11 (29%) 18 (72%) 10 (44%) 4 (24%) 2 (10%) 12 (52%)Other 1 (3%) 1 (4%) 4 (17%) 3 (18%) 0 3 (13%)

Associated Surgical Palliation

Prior to any surgery 2 (5%) 2 (8%) 6 (26%) 4 (24%) 0 2 (9%)S/p Stage I palliation 3 (8%) 0 2 (9%) 0 0 0S/p Stage 2 palliation 6 (16%) 6 (24%) 7 (30%) 5 (29%) 5 (24%) 8 (35%)S/p Fontan 6 (16%) 7 (28%) 2 (8%) 3 (18%) 11 (52%) 2 (9%)S/p other surgical palliation

21 (55%) 10 (40%) 6 (26%) 5 (29%) 5 (24%) 11 (47%)

SVT indicates supraventricular tachycardia; NOS, not otherwise specified; IQR, interquartile range (25th percentile, 75th percentile); d, days; m, months; and y, years; inpt, inpatient.

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Table S3. Univariate Analysis of Patient Factors by Tachyarrhythmia Type

EAT

N = 38

Atrial Fibrillation Atrial Flutter

N = 25

Re-entrant SVT

N = 23

SVT NOS

N = 17

Junctional

N = 21

Ventricular

N = 23

HR(95% CI)

HR(95% CI)

HR(95% CI)

HR(95% CI)

HR(95% CI)

HR(95% CI)

AVVR ≥ moderate 2.08*(1.09-3.96)

2.94*(1.27-6.80)

1.30(0.56-2.99)

3.74*(1.38-10.10)

4.28*(1.72-10.62)

2.32(1.00-5.40)

Functional Single Ventricle

4.00*(1.23-13.07)

1.29(0.48-3.51)

7.55*(1.02-56.03)

5.16(0.68-38.92)

6.64(0.89-49.48)

1.68(0.57-4.97)

Pulmonary venous obstruction

5.56*(2.83-10.93)

0.43(0.06-3.30)

1.48(0.54-4.06)

4.96*(1.91-12.93)

2.46(0.92-6.53)

1.06(0.30-3.69)

Isomerism TypeLAI (ref)

RAI

Undetermined

1.00

2.76*(1.21-6.27)

2.26(0.86-5.95)

1.00

0.84(0.34- 2.10)

0.99(0.33-3.00)

1.00

2.56(0.90-7.26)

1.65(0.50-5.41)

1.00

5.21(1.14-23.81)

3.53(0.68-18.17)

1.00

1.30(0.43-3.86)

2.36(0.77-7.22)

1.00

0.58(0.21-1.57)

0.95(0.34-2.63)

Ventricular dysfunction

0.91(0.40-2.07)

1.51(0.64-3.60)

0.40(0.09-1.72)

1.94(0.68-5.51)

1.42(0.52-3.89)

1.52(0.61-3.76)

EAT indicates ectopic atrial tachycardia; SVT, supraventricular tachycardia; NOS, not otherwise specified; HR, hazard ratio; CI, confidence interval; AVVR, atrioventricular valve regurgitation; LAI, left atrial isomerism; RAI, right atrial isomerism; ref, reference..All univariate analyses performed with univariate Cox regression model. For multiple comparisons, p < 0.017 was considered significant after Bonferroni adjustment was applied. Otherwise, p < 0.05 was considered significant. * Variables achieving significant p values.

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Table S4. Characteristics of Patients with Atrioventricular Block

Total CCAVB HG AVB Surgical AVB22 15 4 3

CharacteristicMale 10 (46%) 6 (40%) 2 (50%) 2 (67%)Death or transplant 9 (41%) 6 (40%) 2 (50%) 1 (33%)Median age at diagnosis(range)

Prenatal(PN, 2 y)

Prenatal(PN, Birth)

8 d(PN, 10 m)

6 m(1 m, 2 y)

Hydrops 4 (18%) 4 (27%) 0 NAFunctional Single Ventricle

10 (46%) 7 (47%) 3 (75%) 0

Permanent PM 19 (86%) 13 (87%) 3 (75%) 3 (100%)Median Age at PM(IQR)

6 d(2 d, 1 m)

5 d (1 d, 9 d)

11 d(3 d, 3 y)*

6 m(1 m, 2 y)*

CCAVB indicates congenital complete atrioventricular block; HG, high grade; AVB, atrioventricular block; PN, prenatal; SV, single ventricle; IQR, interquartile range (25th percentile, 75th percentile); d, days; m, months; and y, years.*Expressed as range

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Table S5. Characteristics of Patients with Pacemakers

Reason for Pacemaker

Sinus Node Dysfunction and/or Sinus Bradycardia

Low Grade 2nd degree

AVB

HG AVB CCAVB Surgical AVB Tachycardia Related

Treatment

Unknown

13 3 3 13 3 15 1CharacteristicsMale 4 (31%) 2 (67%) 1 (33%) 5 (38%) 2 (67%) 8 (53%) 1 (100%)Functional Single Ventricle

6 (46%) 3 (100%) 2 (67%) 6 (46%) 0 12 (80%) 1 (100%)

ICD Upgrade - 1 (33%) - - - 2 (13%) -Median Age at Implant (IQR)

4 y(11 m, 7.5 y)

6 y(10 m, 9 y)**

11 d(3 d – 3 y)**

5 d(1 d, 9 d)

6 m(1 m, 2 y)**

9 y(5 y, 24 y)

6 m

AVB indicates atrioventricular block; HG, high grade; CCAVB, congenital complete atrioventricular block; PN, prenatal; SV, single ventricle; ICD, implantable cardioverter defibrillator; IQR, interquartile range (25th percentile, 75th percentile); d, days; m, months; and y, years.**Expressed as range

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Table S6. Arrhythmia Related Deaths

Pt Sex Race/ Ethnicity

Age at death

Isomerism Significant History

Tachyarrhythmia Deaths

1 M Hispanic 2 d RAI Post-operative narrow complex tachycardia with subsequent degeneration into terminal bradycardia. Occurred following TAPVR repair and placement of BTS.

Single ventricle.

2 F White 3 y LAI Post-operative narrow complex tachycardia with subsequent degeneration into ventricular fibrillation. Occurred following Fontan palliation with concomitant placement of a single chamber pacemaker for bradycardia.

Single ventricle.

3 F Hispanic 8 m RAI Expired in the hospital at 8 months of age with an intractable episode of atrial tachycardia.

Single ventricle. Could not be palliated beyond a BTS due to persistently elevated pulmonary vascular resistances.

4 F White 10 y LAI In hospital torsades de pointes arrest during initiation of Sotalol for persistent atrial tachycardia.

Single ventricle. Fontan palliation with progressive cyanosis from intrapulmonary arteriovenous malformations.

5 F Black 17 y LAI VF arrest occurring within 24 hours of a diagnostic catheterization. No antecedent history of arrhythmias

Unrepaired unobstructed TAPVR and primum atrial septal defect with pulmonary hypertension and mild ventricular dysfunction.

Bradyarrhythmia Deaths

6 M Black 1 d Mixed Fetal CCAVB with hydrops prompting premature delivery at 30 weeks. Single right ventricle with severe dysfunction.

7 F Hispanic 11 d LAI Fetal CCAVB with hydrops prompting premature delivery at 34 weeks.

Biventricular anatomy. Sinus venosus ASD with partial anomalous pulmonary venous return. Dysmorphic. Congenital hydrocephalus. Anomalous corpus callosum.

8 M White 17 d RAI Post-operative high grade AVB following BTS placement for ductal dependent pulmonary circulation. Died from hemodynamic instability despite placement of temporary pacing wires.

Single ventricle. Clinical sepsis.

Pt indicates patient; M, male; F, female; d, days; w, weeks; m, months; y, years; RAI, right atrial isomerism; LAI, left atrial isomerism; TAPVR, total anomalous pulmonary venous return; BTS, Blalock-Taussig shunt; CCAVB, congenital complete atrioventricular block; ASD, atrial septal defect; AVB, atrioventricular block.

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