Abstract
Background
A sinus venosus defect is the least common form of atrial septal defect (ASD). Both sinus venosus ASD and right ventricular (RV) infarction are characterized by RV dysfunction, right heart failure, and arrhythmias.
Case Summary
A young man with acute occlusion of a small right coronary artery, RV infarction, and cardiogenic shock was suspected of having an underlying ASD because of disproportionate RV and right atrial enlargement, hypoxemia, and prolonged hypotension. ASD identification allowed corrective surgery for ASD as well as coronary artery bypass surgery after his infarction.
Discussion
Underlying congenital heart disease should be suspected in the setting of disproportionate right-sided chamber enlargement and hypoxemia in acute coronary syndromes.
Take-Home Message
This case demonstrates the vulnerability of a chronic volume-overloaded RV to acute myocardial injury and the importance of suspecting underlying congenital heart disease in the presence of disproportionate right atrial enlargement.
Key words: atrial septal defect, congenital heart defect, hypoxemia, imaging, myocardial infarction, right ventricle
Visual Summary
Visual Summary.
Anatomical Changes post Right Myocardial Infarct vs Sinus Venous Defect with Right Myocardial Infarct
(A) Dilated RV after RV infarct. (B) Dilated RV and RA as seen in sinus venosus defect with right myocardial infarction. RA = right atrium; RV = right ventricle.
History of Presentation
A 43-year-old man presented to an outer metropolitan hospital with 2 hours of severe anginal chest pain that radiated to the anterior neck and arms bilaterally. Prior to this presentation there were no cardiorespiratory symptoms.
On examination, our patient was hypotensive with a systolic blood pressure of 75 mm Hg; he had a regular pulse rate at 64 beats/min and was hypoxic with room air oxygen saturation of 86%. The jugular venous pulse was distended, and heart sounds were dual with no murmurs. Both lung fields were clear on auscultation, and there was no peripheral edema.
Take-Home Message
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•
This case demonstrates the vulnerability of a chronic volume-overloaded right ventricle to acute myocardial injury and the importance of suspecting underlying congenital heart disease in the presence of disproportionate right atrial enlargement.
Past Medical History
The patient's medical history included type 2 diabetes mellitus and hypercholesterolemia. He was a current smoker with a 10-pack-year history.
Investigations
Twelve-lead electrocardiogram revealed a junctional rhythm with 1 mm of ST-segment elevation in the inferior leads and reciprocal ST-segment depression in aVL (Figure 1). As primary angioplasty service was not available at the initial presenting hospital, thrombolysis with tenecteplase was administered. After crystalloid fluid resuscitation and a brief period of inotropic support, hemodynamic stability was achieved, and the patient was transferred to a tertiary teaching hospital.
Figure 1.
Admission and Discharge Electrocardiograms
(A) Inferior ST-segment elevation myocardial infarction with junctional rhythm. (B) Atrial ectopic rhythm with resolution of ST-segment changes.
After transfer, coronary angiography was performed, leading to percutaneous intervention of the culprit nondominant small-vessel right coronary artery (RCA) ostial occlusion with a drug-eluting stent (Figure 2, Videos 1 and 2). The patient was also found to have incidental significant stenoses: 70% left anterior descending artery and 90% obtuse marginal artery. Troponin T levels peaked at 3,727 ng/L during admission, and electrocardiographic changes resolved after percutaneous coronary intervention (PCI) to the RCA. The patient was placed on dual antiplatelet therapy with aspirin and clopidogrel.
Figure 2.
Coronary Angiogram Primary PCI
(A) Ostially occluded RCA. (B) TIMI flow grade 3 after drug-eluting stent to ostial/proximal RCA. PCI = percutaneous coronary intervention; RCA = right coronary artery.
Transthoracic echocardiography (TTE) demonstrated normal left ventricular (LV) size and systolic function (LV ejection fraction: 55%-60%), apparently normal left atrium, but a severely dilated right ventricle (RV) with mild to moderate systolic dysfunction, a moderately dilated right atrium (RA), moderate tricuspid regurgitation, and no detectable pulmonary hypertension. The dilation of the RA was considered disproportionate in the setting of acute myocardial infarction, and in light of this, a saline contrast study was performed. This revealed a large, early positive, right-to-left atrial level shunt (Figure 3, Videos 3 to 5) suggestive of a sinus venosus atrial septal defect (ASD).
Figure 3.
TTE + Bubble Study
(A) Severely dilated RV/RA. (B) No color flow across atrial septum. (C) Early positive bubble study (bubbles in left-sided and right-sided chambers almost simultaneously). RA = right atrium; RV = right ventricle; TTE = transthoracic echocardiography.
Because hypotension persisted after PCI to the RCA, the patient underwent computed tomography pulmonary angiography to exclude pulmonary embolism. Although no pulmonary embolism was seen, it confirmed an atrial-level shunt with a superior sinus venosus ASD and partial anomalous pulmonary venous return of the right upper and middle pulmonary veins into the superior vena cava (Figure 4, Video 6). Transesophageal echocardiography confirmed these findings (Figures 5 and 6, Videos 7 to 11), with evidence of predominant left-to-right flow across the sinus venosus defect and intermittent bidirectional flow, severely dilated RV with mild to moderate systolic dysfunction, moderate tricuspid regurgitation, and a pulmonary-to-systemic flow (Qp:Qs) ratio of 2.2, indicating a hemodynamically significant shunt (Videos 12 and 13).
Figure 4.
CT Pulmonary Angiography
Right upper (RU) and right middle (RM) pulmonary veins (PVs) draining into SVC. CT = computed tomography; SVC = superior vena cava.
Figure 5.
Transesophageal Echocardiography Findings
(A) Severely dilated RV/RA. (B and C) Bicaval view of sinus venosus ASD with bidirectional shunt. (D) Basal view with RU PV (right upper pulmonary vein) draining into the SVC. ASD = atrial septal defect; RA = right atrium; RV = right ventricle; SVC = superior vena cava.
Figure 6.
Transesophageal Echocardiography Findings
(A) No secundum ASD. (B) Moderate to severe tricuspid regurgitation. (C) Normal estimated pulmonary artery systolic pressure (18 mm Hg + RAP). TEE Qp:Qs ratio was 2.2. (D) Two- and 3-chamber views of LV with normal systolic function. ASD = atrial septal defect; LV = left ventricle; Qp:Qs = pulmonary-to-systemic flow; RAP = right atrial pressure; TEE = transesophageal echocardiography.
Cardiac magnetic resonance imaging confirmed a Qp:Qs ratio of 1.8 as well as the sinus venosus defect and partial anomalous pulmonary venous return, with normal LV size (LV end-diastolic volume index: 50 mL/m2) and systolic function (LV ejection fraction: 64%), severely dilated RV (RV end-diastolic volume index: 161 mL/m2) and mild to moderately reduced systolic function (RV ejection fraction: 38%), and no abnormal late gadolinium enhancement in the LV or RV despite recent infarction (Figure 7, Videos 14 and 15). Percutaneous right heart catheterization also confirmed a Qp:Qs of 2.0 as well as step up in oxygen saturations from the superior vena cava and inferior vena cava to the RA, and revealed mild mixed pre- and postcapillary pulmonary hypertension (Figure 8).
Figure 7.
Results of Right Heart Catheterization With Oxygen Saturation Levels
Step up in oxygen saturations from the SVC/IVC to the RA. Mild mixed pre- and postcapillary pulmonary hypertension with a Qp:Qs ratio of 2.0. CI = cardiac index; CO = cardiac output; HR = heart rate; IVC = inferior vena cava; PA = pulmonary artery; PVR = pulmonary vascular resistance; Qp:Qs = pulmonary-to-systemic flow; RA = right atrium; RV = right ventricle; SV = stroke volume; SVC = superior vena cava.
Figure 8.
Cardiac MRI
(A) Four-chamber severely dilated RA and RV with mild-moderate systolic impairment. (B) No inferior wall LGE. (C) Axial sequence showing right upper and right middle lobe PV draining into the SVC. (D) No RV LGE. MRI = magnetic resonance imaging; RA = right atrium; RV = right ventricle; PV = pulmonary vein; SVC = superior vena cava.
Management/Intervention
After a heart team meeting, the patient underwent cardiac surgery on aspirin monotherapy, with a bovine pericardial patch to baffle the right superior pulmonary vein into the left atrium and close the sinus venosus ASD, and coronary artery bypass grafting with a left internal mammary artery–to–left anterior descending artery and radial T graft to the obtuse marginal artery. The tricuspid valve was repaired with a 32-mm Cosgrove annuloplasty ring (Edwards Lifesciences). The patient recovered well after surgery, with no postoperative complications.
Outcome and Follow-Up
TTE at 2 months postoperatively demonstrated normal LV size and systolic function (LV ejection fraction: 56%), improved RV size, which was still mildly dilated (RV diameter at base: 40 mm from previous 53 mm) and mild systolic dysfunction, and a well-seated tricuspid annuloplasty ring with trivial regurgitation (Figure 9, Videos 16 and 17).
Figure 9.
TTE 2 Months Postsurgery
(A) Mildly dilated RV with mild systolic impairment. (B) TV annuloplasty ring with no transvalvular or paravalvular regurgitation. (C) Postoperative RV measurements (RV base: 40 mm). (D) Preoperative RV measurements for comparison (RV base: 53 mm). RV = right ventricle; TTE = transthoracic echocardiography; TV = tricuspid valve.
Discussion
This case demonstrates the propensity toward hemodynamic instability and cardiogenic shock in a patient experiencing RCA territory acute myocardial ischemia with an underlying undiagnosed complex atrial shunt and a vulnerable chronically volume-overloaded RV.
A sinus venosus defect is the least common form of ASD, accounting for ∼2% to 10% of all ASDs.1 It is characterized by a defect typically located at the junction between the superior vena cava and RA resulting in left-to-right atrial shunting and subsequent RA and RV dilatation, leading to progressive RV dysfunction, right heart failure, and arrhythmias. It is commonly associated with anomalous pulmonary venous drainage (typically right superior ± middle pulmonary vein) into the superior vena cava.
Unrepaired sinus venosus ASDs often remain asymptomatic at least until the third decade of life.2 Initial presenting symptoms include exertional dyspnea. As in our patient, it may also be discovered during presentation and investigation of a separate intercurrent illness. Although TTE is the initial diagnostic test in patients suspected to have a sinus venosus ASD, its overall sensitivity is poor.3 TTE usually demonstrates a dilated and volume-loaded RV with RA dilatation but no clearly discernible atrial-level shunt with color Doppler; however, as in this case, agitated saline contrast injection can identify the presence of an atrial-level shunt and prompt further cross-sectional imaging to define shunt anatomy. Transesophageal echocardiography is more sensitive for diagnosis of sinus venosus ASDs, particularly given the proximity of the transducer to the defect.1
Isolated RV myocardial infarction account for ∼3% of all myocardial infarctions4 and is commonly associated with acute hypotension, cardiogenic shock, and atrioventricular nodal dysfunction resulting in heart block. In our case, a junctional rhythm was present at presentation secondary to flush occlusion of a small RCA proximal to the sinoatrial branch. While the sinoatrial branch arises from the RCA in 63% of cases and from the left circulation in the remainder of cases, the sinoatrial blood supply is not associated with coronary arterial dominance, in contrast with the atrioventricular nodal artery, as seen in our case.5
RV infarction typically occurs owing to dominant RCA occlusion, and these can be large where there is also involvement of the inferior or inferolateral wall of the LV. However, as in our case, isolated RV infarction may occur as a result of a nondominant RCA occlusion proximal to the RV branch.6 It is likely that our patient with a sinus venosus ASD and volume-loaded RV was vulnerable to the effects of RV ischemia/infarction on top of probably pre-existing RV dilatation and volume overload. However, TTE imaging before the current ACS presentation was not available to ascertain the degree of pre-existing RV dilatation. Nondominant ostial RCA occlusion of a small-caliber vessel perhaps explains the lack of significant RV infarction seen on cardiac magnetic resonance imaging of our patient.
Data on the recovery of RV size and function after sinus venosus ASD correction in adults, as seen in our patient, are limited, however a previous retrospective study has demonstrated improvement in RV size within the first 24 hours postsurgery, followed by gradual recovery in RV basal diameter, with no significant change in RV function.7 RV recovery after infarction may also be related to the RV's low myocardial demand, collateral blood supply from the left circulation (not evident on coronary angiography in our patient), and/or theoretical collateral blood supply via the thebesian veins.4 In our case, RV recovery after PCI was limited by the underlying RV volume loading due to the sinus venosus ASD. Surgical correction of the defect clearly was important for longer term recovery of RV size and function.
As a practice point, acute RA dilatation is not typical of acute RV infarction.4 This, together with severe hypoxemia in the absence of pulmonary edema, prompted investigation for a left-to-right shunt and led to subsequent diagnosis with multimodality imaging.
Conclusions
We have reported the case of a 43-year-old man with cardiogenic shock after occlusion of a small nondominant RCA and an underlying undiagnosed large sinus venosus ASD suspected on the basis of disproportionate RA dilatation.
Funding Support and Author Disclosures
The authors have reported that they have no relationships relevant to the contents of this paper to disclose.
Footnotes
The authors attest they are in compliance with human studies committees and animal welfare regulations of the authors’ institutions and Food and Drug Administration guidelines, including patient consent where appropriate. For more information, visit the Author Center.
Appendix
For supplemental videos, please see the online version of this paper.
Appendix
Coronary Angiogram During Primary PCI Showing Ostially Occluded RCA
PCI = percutaneous coronary intervention; RCA = right coronary artery.
Coronary Angiogram During Primary PCI
TIMI flow grade 3 after drug-eluting stent to the ostial/proximal RCA. PCI = percutaneous coronary intervention; RCA = right coronary artery.
TTE + Bubble Study
No color flow across the atrial septum. TTE = transthoracic echocardiography.
TTE + Bubble Study
Early positive bubble study (bubbles in the left-sided and right-sided chambers almost simultaneously). TTE = transthoracic echocardiography.
TTE Showing Severely Dilated RV and RA
RA = right atrium; RV = right ventricle; TTE = transthoracic echocardiography.
CT Pulmonary Angiography
Right upper and right middle pulmonary veins draining into the superior vena cava, sinus venosus defect, and severely dilated right-sided chambers. CT = computed tomography.
TEE of Sinus Venosus ASD
Bicaval view of sinus venosus ASD with bidirectional shunt. ASD = atrial septal defect; TEE = transesophageal echocardiography.
TEE of Right Upper Pulmonary Vein Draining Into SVC
Basal view with right upper pulmonary vein draining into superior vena cava. TEE = transesophageal echocardiography.
TEE Showing Moderate to Severe TR
TEE = transesophageal echocardiography; TR = tricuspid regurgitation.
TEE Showing Severely Dilated RV and RA
RA = right atrium; RV = right ventricle; TOE = transesophageal echocardiography.
TEE of Sinus Venosus ASD
Bicaval view of sinus venosus ASD with bidirectional shunt. ASD = atrial septal defect; TEE = transesophageal echocardiography.
TEE Demonstrating No Secundum ASD
ASD = atrial septal defect; TEE = transesophageal echocardiography.
TEE Showing Normal Left Ventricular Systolic Function
TEE = transesophageal echocardiography.
Cardiac MRI Showing Severely Dilated RA and RV With Mild-Moderate Systolic Impairment
RA = right atrium; RV = right ventricle.
Cardiac MRI
Axial sequence showing right upper and right middle lobe PV draining into the SVC. SVC = superior vena cava.
TTE of TV Annuloplasty Ring 2 Months Postsurgery
TV annuloplasty ring with no transvalvular or paravalvular regurgitation. TTE = transthoracic echocardiography; TV = tricuspid valve.
TTE 2 Months Postsurgery
Mildly dilated RV with mild systolic impairment. RV = right ventricle; TTE = transthoracic echocardiography.
References
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Associated Data
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Supplementary Materials
Coronary Angiogram During Primary PCI Showing Ostially Occluded RCA
PCI = percutaneous coronary intervention; RCA = right coronary artery.
Coronary Angiogram During Primary PCI
TIMI flow grade 3 after drug-eluting stent to the ostial/proximal RCA. PCI = percutaneous coronary intervention; RCA = right coronary artery.
TTE + Bubble Study
No color flow across the atrial septum. TTE = transthoracic echocardiography.
TTE + Bubble Study
Early positive bubble study (bubbles in the left-sided and right-sided chambers almost simultaneously). TTE = transthoracic echocardiography.
TTE Showing Severely Dilated RV and RA
RA = right atrium; RV = right ventricle; TTE = transthoracic echocardiography.
CT Pulmonary Angiography
Right upper and right middle pulmonary veins draining into the superior vena cava, sinus venosus defect, and severely dilated right-sided chambers. CT = computed tomography.
TEE of Sinus Venosus ASD
Bicaval view of sinus venosus ASD with bidirectional shunt. ASD = atrial septal defect; TEE = transesophageal echocardiography.
TEE of Right Upper Pulmonary Vein Draining Into SVC
Basal view with right upper pulmonary vein draining into superior vena cava. TEE = transesophageal echocardiography.
TEE Showing Moderate to Severe TR
TEE = transesophageal echocardiography; TR = tricuspid regurgitation.
TEE Showing Severely Dilated RV and RA
RA = right atrium; RV = right ventricle; TOE = transesophageal echocardiography.
TEE of Sinus Venosus ASD
Bicaval view of sinus venosus ASD with bidirectional shunt. ASD = atrial septal defect; TEE = transesophageal echocardiography.
TEE Demonstrating No Secundum ASD
ASD = atrial septal defect; TEE = transesophageal echocardiography.
TEE Showing Normal Left Ventricular Systolic Function
TEE = transesophageal echocardiography.
Cardiac MRI Showing Severely Dilated RA and RV With Mild-Moderate Systolic Impairment
RA = right atrium; RV = right ventricle.
Cardiac MRI
Axial sequence showing right upper and right middle lobe PV draining into the SVC. SVC = superior vena cava.
TTE of TV Annuloplasty Ring 2 Months Postsurgery
TV annuloplasty ring with no transvalvular or paravalvular regurgitation. TTE = transthoracic echocardiography; TV = tricuspid valve.
TTE 2 Months Postsurgery
Mildly dilated RV with mild systolic impairment. RV = right ventricle; TTE = transthoracic echocardiography.