SECTION ONE

Shunts
Part I
Atrial Septal Defects/Abnormal Pulmonary
Venous Return
Case 1

Right Heart Enlargement of Uncertain Cause

(Sinus Venosus Atrial Septal Defect)
Ju-Le Tan, Wei Li, and Elisabeth Bédard

Age: 56 years
Gender: Female
Personal information: Grandmother
Working diagnosis: Unexplained shortness of breath for several months

HISTORY CURRENT MEDICATIONS

The patient had been well all her life. She had given birth to None
two daughters without any difficulties and more recently had
been looking after her two young grandchildren. She had never
been hospitalized nor had she required an operation. She was PHYSICAL EXAMINATION
postmenopausal. BP 124/76 mm Hg, HR 60 bpm, oxygen saturation 100% on
During a recent checkup with her general practitioner a room air
murmur was heard. On questioning she admitted to feeling
more short of breath with exertion. The patient was subse- Height 160 cm, weight 65 kg, BSA 1.7 m2
quently referred for further evaluation. Neck veins: Venous waveform was normal and not elevated.
She had no other risk factors for coronary artery disease. There
was no family history of congenital or acquired heart disease. Lungs/chest: Clear
She does not smoke.
Heart: The rhythm was regular. There was no left parasternal
C o m m e n t s : Although the differential diagnosis for a 56- heave on palpation. The pulmonary component of the second
year-old woman with exertional dyspnea is extremely long, it heart sound was delayed, but was neither loud nor fixed.
is not uncommon for a congenital heart defect to present for the There was a soft systolic ejection murmur at the upper left
first time in the fifth or sixth decade of life. ASDs would be by sternal border.
far the most common among them. Abdomen: The abdomen was normal with no ascites or
organomegaly.
CURRENT SYMPTOMS Extremities: The extremities were not edematous.
There were no symptoms other than exertional dyspnea,
although the patient admitted to “slowing down” in the last few Pertinent Negatives
years and to avoiding stairs and hills. No clubbing was seen.
Specifically she denied recent fevers, chest pains, palpita-
tions, and gastrointestinal or vaginal bleeding. C o m m e n t s : This patient has no obvious clinical signs to
suggest right ventricular hypertrophy or dilatation. Patients
NYHA class: I–II with an ASD often have fixed splitting of the second heart

Cases in Adult Congenital Heart Disease  1

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 sound, but its absence does not rule out an ASD, such as a sinus CHEST X-RAY
venosus ASD. The absence of a loud pulmonary component of
Shunts / Atrial Septal Defects/Abnormal Pulmonary Venous Return

the second heart sound makes pulmonary hypertension

unlikely. A soft systolic ejection murmur is very common due
to increased pulmonary blood flow in such patients.

LABORATORY DATA
Hemoglobin 14 g/dL (11.5–15.0)
Hematocrit/PCV 41% (36–46)
MCV 90 fL (83–99)
Platelet count 191 × 109/L (150–400)
Sodium 138 mmol/L (134–145)
Potassium 4.0 mmol/L (3.5–5.2)
Creatinine 0.61 mg/dL (0.6–1.2)
Blood urea nitrogen 5.3 mmol/L (2.5–6.5)

C o m m e n t s : No abnormalities were seen. Her breathless-

ness could not be explained by anemia.

ELECTROCARDIOGRAM
Figure 1-2  Posteroanterior projection.
I aVR C1 C4

Findings
II aVL C2 C5
Cardiothoracic ratio: 60%

There is mild cardiomegaly with mild RA dilatation. The central

III aVF C3 C6
pulmonary arteries are dilated with increased pulmonary vas-
cular markings.
C o m m e n t s : The CXR findings here combined with the
II subtle ECG findings are suspicious for right heart enlargement
(lateral CXRs are not routinely done at our hospital). Further
imaging should focus on a potential source of a left-to-right shunt.
Figure 1-1  Electrocardiogram.
EXERCISE TESTING
Findings Not performed
Heart rate: 64 bpm
QRS axis: +107° ECHOCARDIOGRAM
QRS duration: 84 msec
Overall Findings
Sinus rhythm with normal AV conduction. There was an inver­ The LV was normal in size and function with a competent
ted P-wave in lead III and a prominent R in leads V1–2. mitral valve.
The RV was moderately dilated.
C o m m e n t s : The rightward axis and the R in V1 suggest The tricuspid valve was competent. The RA and LA were
possible enlargement of the RV, although criteria for RV moderately dilated.
hypertrophy were not present. This should prompt consider-
ation for an ASD.
The presence of a negative P-wave in lead III as seen in
this patient is a typical feature of a sinus venosus ASD. The P-
wave vector is approximately −20 degrees, so the term coronary
sinus or low atrial rhythm would be appropriate. The sinus node
may also be affected as it lies in the vicinity of the defect
or adjacent to the site of an anomalous pulmonary venous
connection.

Figure 1-3  Parasternal long-axis view.

2  Cases in Adult Congenital Heart Disease

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Findings
RV dilatation is seen. The LV and LA were normal.

Right Heart Enlargement of Uncertain Cause (Sinus Venosus Atrial Septal Defect)
C o m m e n t s : The RV finding should prompt the sonogra-
pher to search extensively for evidence of a left-to-right shunt,
most likely across an ASD, and/or for the presence of anoma-
lous pulmonary veins.

RA

RUPV

Figure 1-5  Apical four-chamber view.

Findings
There was an anomalous drainage of the right upper pulmo-
nary vein (RUPV) to the RA. The sinus venosus ASD measured
Figure 1-4  Apical four-chamber view. 14 mm.

Findings C o m m e n t s : Sinus venosus ASDs are very commonly

Both the RA and RV were moderately dilated. In addition, associated with partial anomalous pulmonary venous drainage;
there was a 15-mm sinus venosus ASD with a left-to-right the anomalous drainage usually involves the RUPV, which
shunt. often drains into the SVC and RA junction.

C o m m e n t s : This shows again the moderately dilated and MAGNETIC RESONANCE IMAGING
volume overloaded RV. The cause is a left-to-right shunt
through a defect high on the atrial septum (at the bottom of this
image).

Figure 1-6  Magnetic resonance image.

Cases in Adult Congenital Heart Disease  3

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 Ventricular Volume Quantification usually done in a routine study. The imager must know the
clinical question at hand to provide useful data. Although not
Shunts / Atrial Septal Defects/Abnormal Pulmonary Venous Return

LV (Normal range) RV (Normal range)

performed in this case, a contrast-enhanced magnetic resonance
EDV (mL) 81 (52–141) 187 (58–154) angiogram is recommended for visualizing all pulmonary
ESV (mL) 36 (13–51) 87 (12–68) veins.
SV (mL) 45 (33–97) 100 (35–98)
EF (%) 56 (59–77) 53 (55–79)
EDVi (mL/m2) 48 (56–90) 110 (53–90)
ESVi (mL/m2) 21 (14–33) 51 (11–37)
SVi (mL/m2) 26 (37–62) 59 (17–37)

Findings
The RA and RV were dilated with normal RV systolic function.
The pulmonary/systemic flow ratio (Qp/Qs) was 2.2 : 1 based
on flow measurements.

C o m m e n t s : Cardiac MRI was primarily performed to

clarify the pulmonary venous drainage and confirm the ECG
findings. Estimates of ventricular mass, flow, and shunt volume
can also be obtained noninvasively from the MRI study. Shunt
volume can be calculated by measuring the difference between
pulmonary artery (PA) flow and aortic flow. MRI confirmed
that the upper right pulmonary vein drains into the SVC at its Figure 1-8  Oblique sagittal plane at the level of the high right atrium,
junction with the RA. Cardiac surgeons would normally inspect viewed from the left ventricular apex.
the four pulmonary veins during repair; hence it may not be
necessary to perform a routine MRI when the diagnosis of sinus
venosus ASD has been established. Nevertheless, it is helpful Findings
to have complete data on the anomalous pulmonary venous The aortic root is seen in cross section in the center of the image,
drainage in hand before surgery, as the anomalous vein may with the left PA above it. Just below the aorta in this view there
occasionally have a longer and tortuous course, draining at a is a communication between the atria. This is the location where
more distal site, which in turn requires a more complex the upper RA and LA are usually separated by an infolding of
repair. the atrial wall, which is absent here.

C o m m e n t s : This demonstrates a sinus venosus ASD.

This was associated with anomalous drainage of the RUPV to
the SVC (from far left of image). The other pulmonary veins
drained normally to the LA. No other defects were found.
Note the relatively small size of the aorta (in short axis) com-
pared to the size of the left PA, reflecting the long-standing low
cardiac output and systemic “run-off” (“steal”) that this patient
has been subjected to throughout her life because of significant
left-to-right shunting at atrial level.

CATHETERIZATION
Hemodynamics
Heart rate 60 bpm
Pressure Saturation (%)
High SVC 66
Figure 1-7  Oblique coronal plane. Low SVC 79
IVC 82
Findings RA mean 9 84
The aortic valve and aorta are in the center of the image. The RV 35/9 88
SVC runs parallel to the aorta. The RUPV can be seen draining PA 34/9 mean 19 86
into the SVC just as it enters the RA. PCWP mean 9
LA
C o m m e n t s : Imaging planes such as this that look for LV 143/11
specific abnormalities of pulmonary venous drainage are not Aorta 128/77 mean 99 97

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 almost completely left to right. The case illustrates that in
patients with evidence of RV enlargement by ECG and no obvious

Right Heart Enlargement of Uncertain Cause (Sinus Venosus Atrial Septal Defect)
128/77 cause, a thorough search for a left-to-right shunt and anomalous
66% mean 99 pulmonary veins should be specifically conducted.
97%
79% 34/9 mean 19 2. Since the patient was only mildly symptomatic, should the
86% sinus venosus ASD be closed?
Objectively, there was evidence of right ventricular dilatation
and significant left-to-right shunt by ECG, MRI, and cardiac
mean 9 catheterization. Even though only mildly symptomatic at present,
84% the patient is likely to deteriorate further with time. Sinus venosus
ASDs with right heart dilatation should be closed regardless of
143/11 symptoms.2,3
Because this lesion is not amenable to catheter-based closure,
35/9 surgery would be required.
88% 3. What is the risk of atrial arrhythmia after closure of the
defect?
82%
Unfortunately, the risk of atrial arrhythmia is not reduced by
surgical closure of an ASD in the older patient.4 During a mean
follow-up of 9 years, atrial fibrillation or flutter was found to
Figure 1-9  Hemodynamic data. have developed in 15% of surgically treated ASD patients.4 The
age at time of surgery (>40 years), the presence of preoperative
atrial flutter or fibrillation, and the presence of postoperative
Calculations atrial flutter or fibrillation or junctional rhythm have been shown
Qp (L/min) 6.86 to be predictors of late postoperative atrial arrhythmias.5 Further-
Qs (L/min) 3.05 more, patients with superior sinus venosus defects are at risk of
Cardiac index (L/min/m2) 1.79 sinus node dysfunction because of the proximity of the defect to
Qp/Qs 2.25 the sinus node. Thus, patients should be followed longer term for
PVR (Wood units) 1.17 the development of atrial flutter or atrial fibrillation, which puts
SVR (Wood units) 29.53 them at risk for cerebral thromboembolism, or for sinus node
dysfunction that may require permanent pacing.
Findings
Hemodynamic measurements are shown. The coronary angio-
gram showed no evidence of coronary artery disease. FINAL DIAGNOSIS
Secundum ASD, sinus venosus type
C o m m e n t s : Diagnostic catheterization was performed to
obtain hemodynamic data including pulmonary vascular resis- Anomalous drainage of the RUPV
tance and also to evaluate the coronary arteries prior to surgery.
It was not essential to obtain the hemodynamic data. PLAN OF ACTION
Hemodynamic data showed a step-up from high SVC to low
SVC, suggesting that the anomalous pulmonary venous connec- Surgical closure of the defect
tion was nearer the lower SVC or SVC-RA junction.
The RV end-diastolic pressure of 9 mm Hg suggested a com-
pliant RV.
INTERVENTION
The calculated Qp/Qs of 2.3 confirmed significant left-to- Open heart surgery, closure of the ASD, and redirection of
right shunting. There was no significant pulmonary hyperten- pulmonary venous drainage
sion, as the mean PA pressure was only 19 mm Hg, and
pulmonary vascular resistance was not elevated.
OUTCOME
Focused Clinical Questions The patient underwent closure of her sinus venosus ASD and
and Discussion Points rerouting of the pulmonary vein to the LA. At surgery the
RUPV was seen draining into the RA at the junction with the
1. What is the diagnosis? SVC, and the right lower pulmonary vein drained directly into
the RA immediately adjacent to the defect. She developed bilat-
The patient has a sinus venosus ASD with anomalous drainage eral pleural effusions postoperatively but had an otherwise
of the RUPV near the defect. Anomalous pulmonary venous uneventful postoperative recovery.
drainage is commonly associated with superior sinus venosus The patient was instructed to take aspirin (75 mg) for 6
ASD,1 which is located superior to the atrial septum and adjacent months.
to the SVC. The true interatrial septum is often intact because the Two weeks postoperatively she had made good recovery
defect is due to the deficiency of infolding of the atrial wall above from her surgery with resolution of her pleural effusions.
the septum. Commonly, the upper or middle right pulmonary vein Transthoracic echocardiography showed no residual shunting
drains directly into the SVC, SVC-RA junction, or into the RA.1 across the site of her previous sinus venosus defect, unob-
Routine ECG or MRI can often miss these findings. Even structed pulmonary venous return, and reduction in RA and
a bubble study may be falsely negative because the shunt is RV dimensions.

Cases in Adult Congenital Heart Disease  5

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 able to climb hills and stairs freely without the dyspnea she had
previously experienced. Fortunately, she has not had any
Shunts / Atrial Septal Defects/Abnormal Pulmonary Venous Return

cardiac arrhythmias perioperatively or subsequently to this

point.

Selected References
1. Gustafson RA, Warden HE, Murray GF, et al: Partial anomalous
pulmonary venous connection to the right side of the heart. J
Thorac Cardiovasc Surg 98(5 Pt 2):861–868, 1989.
2. Vogel M, Berger F, Kramer A, et al: Incidence of secondary pulmo-
nary hypertension in adults with atrial septal or sinus venosus
defects. Heart 82:30–33, 1999.
3. Webb GD, Gatzoulis MA: Atrial septal defects in the adult: Recent
progress and overview. Circulation 114:1645–1653, 2006.
4. Konstantinides S, Geibel A, Olschewski M, et al: A comparison of
surgical and medical therapy for atrial septal defect in adults.
N Engl J Med 333:469–473, 1995.
5. Gatzoulis MA, Freeman MA, Siu SC, et al: Atrial arrhythmia after
surgical closure of atrial septal defects in adults. N Engl J Med
Figure 1-10  Four-chamber, 2D color Doppler echocardiogram. 340:839–846, 1999.

Findings Bibliography
No residual flow from the sinus venosus was visible.
Jost CHA, Connolly HM, Danielson GK, et al: Sinus venosus atrial
septal defect: Long-term postoperative outcome for 115 patients.
C o m m e n t s : Transthoracic echocardiography showed no Circulation 112:1953–1958, 2005.
residual shunting across the site of her previous sinus venosus Roess D, Pascoe JK, Oh CA, et al: Diagnosis of sinus venosus atrial
defect with reduction in right atrial and ventricular dimensions. septal defect with transesophageal echocardiography. Circulation
Her exercise capacity also improved after surgery, and she was 94:1049–1055, 1996.

6  Cases in Adult Congenital Heart Disease

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