Venous Anomalies

Published on 21/06/2015 by admin

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9 Venous Anomalies

Brian D. Soriano

Background

• Isolated congenital anomalies of large systemic veins such as persistent left-sided superior vena cava (SVC) or interrupted inferior vena cava (IVC) have no hemodynamic impact and are usually found incidentally.
• Totally anomalous and partially anomalous pulmonary venous connections are two conditions in which one or more pulmonary vein (PV) segments do not connect directly to the left atrium (LA). Instead, the PV connects with a systemic vein, mixing with deoxygenated blood before returning to the right atrium (RA).

• The anomalous connections, whether total or partial, can occur at any level of systemic venous return: supracardiac such as the innominate veins, cardiac level such as the coronary sinus (CS), or infracardiac such as the IVC (Fig. 9-1).
• Right-sided cardiac or systemic venous dilation will occur in the regions where the anomalous connections occur. With supracardiac connections, for example, the SVC and innominate veins may be dilated.

• In normal anatomy, four separate PVs are the most common arrangement, although normal variations in this number also exist. An entire lung can join a single confluent vein before connecting to the LA. Likewise, each lobe of the right lung can have its own vein connect, leading to five total connections.
• In total anomalous pulmonary venous connection (TAPVC), a right-to-left shunt, typically interatrial, is necessary to supply left ventricular preload.
• In repaired TAPVCs, the incidence of PV stenosis is approximately 11%.
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Figure 9-1 Schematic diagram of total anomalous pulmonary venous connections and their most common arrangements: cardiac (typically to the coronary sinus), infracardiac (vertical vein passes the diaphragm and inserts to the inferior vena cava), and supracardiac (with connection to the innominate vein).

Overview of Echocardiographic Approach

• Direct visualization of PV connections to the LA is typically easier for younger and smaller patients.
• All available transthoracic echocardiography (TTE) windows should be used to evaluate and demonstrate pulmonary or systemic venous connections, whether normal or abnormal. Optimal windows depend on which specific PV is being imaged (Table 9-1).
• Color Doppler maps are useful in confirming an individual systemic or PV connection. Low Nyquist settings, 50 cm/s or less, should be used to ensure adequate color signals. The use of higher settings may lead to a low-signal or even absent color map. PV flow is low velocity, and with some TTE windows, the angle of interrogation can be occasionally perpendicular to the vein.
• For any patient with a history of anomalous PV surgical repairs, individual veins should be evaluated for stenosis (Box 9-1, Fig. 9-2).

TABLE 9-1 RECOMMENDED VIEWS TO EVALUATE PULMONARY VEIN ANATOMY

View Best-Viewed Pulmonary Veins
High parasternal short axis (crab view) RLPV, LUPV, LLPVMore challenging: RUPV
Apical 4 chamber RLPVMore challenging: Left lower pulmonary vein origin is adjacent to the left atrial appendage ostium
Apical 5 chamber / LVOT RUPV, LLPV
Parasternal long axis Left pulmonary veins (upper and lower can be difficult to distinguish)
Subcostal long axis RUPV, RLPV, LUPV, LLPV
Subcostal short axis RUPV

Box 9-1

Postoperative Evaluation of Patients with Repaired TAPVC/PAPVC

• Evaluate individual PV connections.
• Evaluate systemic venous connections and the presence or absence of stenosis.
• Assess for the presence or absence of PHTN.
• In repaired scimitar syndrome patients, evaluate the right PVs as they course from the IVC into the LA.
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Figure 9-2 A, Left lower pulmonary vein (PV) stenosis. Aliased flow and a narrow vena contracta are present. B, Spectral Doppler of the stenosis showing continuous flow and a mean gradient of 7 mm Hg.

Anatomic Imaging

Pulmonary Veins

• A high parasternal short axis (SAX) view, angled inferiorly toward the LA, creates the “crab” view (Fig. 9-3). In this plane, four PVs can be visualized at once. Care must be taken to ensure the left atrial appendage is not confused for the left upper PV (LUPV).
• Right parasternal and subcostal views can help confirm the presence of a normal right upper PV (RUPV) connection; the SVC serves as the anatomic landmark because the RUPV courses directly posterior to it (Fig. 9-4). Other, less commonly used windows can be applied to identify normal connections. For example, from the parasternal long axis (LAX) view, a left-sided PV connection can be detected by two-dimensional (2D) and color imaging (Fig. 9-5).
• Size discrepancy between the IVC and SVC can be a subtle sign of anomalous connections; the systemic vein receiving the PV connection will be dilated out of proportion to the remaining systemic veins.
• In scimitar syndrome, part or all of the right-sided PVs connect anomalously to the IVC. The PVs are oriented more vertically and become more dilated as they approach the heart, creating a curved swordlike (“scimitar”) appearance on a chest radiograph (Fig. 9-6).
• In unrepaired TAPVC

• Obstruction can occur in the PV pathways and is more likely associated with infracardiac and supracardiac types. Cardiac-level TAPVC is less likely to be obstructed.
• An obligate and unrestricted right-to-left interatrial shunt is almost always present in any form.

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Figure 9-3 Crab view of the left atrium (LA) (A) and views of the individual venous connections (B).

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Figure 9-4 Two different views of the right upper pulmonary vein (RUPV) from a subcostal short axis (SAX) plane (A) and subcostal long axis (LAX) plane (B). The SVC is located just outside the scan plane. C, RUPV from a two-dimensional view.

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Figure 9-5 View of a left-sided sided PV from a parasternal long axis view.

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Figure 9-6 Chest radiograph of a patient with scimitar syndrome. The arrow indicates the scimitar vein, which anomalously drains right PV flow to the IVC.

Systemic Veins

• Table 9-2 provides an overview of how systemic venous anomalies may be identified.
• A dilated CS should raise the suspicion for the presence of a left-sided SVC (LSVC). Left parasternal views and suprasternal notch views can be used to help visualize the LSVC. The LSVC can be visualized by starting along the left clavicle and angling inferiorly. Low Nyquist (20 cm/s) color Doppler will aid in visualization.

• The presence or absence of a CS septal defect should be evaluated. Intravenous microbubble contrast can be injected in the left arm to evaluate for a right-to-left shunt via the LSVC and directly into the LA by way of this rare systemic venous anomaly.
• If an LSVC is present, usually a normal right-sided SVC (RSVC) is also present.
• A bridging innominate vein may be present between the two vessels.
• Rarely, an isolated LSVC to dilated CS can exist simultaneously with an absent RSVC.

• Interrupted IVC

• Congenital anomaly where the hepatic IVC segment is absent. Lower body systemic veins drain via a hemiazygos vein that eventually drains to the SVC.
• From a transverse abdominal view, a dilated azygos vein can be viewed in cross section and will typically be located adjacent to the vertebral bodies of the spine (Fig. 9-7).
• The azygos arch and SVC may appear dilated due to the extra blood flow (Fig. 9-8).

• The retroaortic innominate vein (Fig. 9-9)

• Courses underneath the aortic arch, instead of superiorly.
• Is best viewed from a suprasternal notch view.

TABLE 9-2 ECHOCARDIOGRAPHIC CUES FOR CONGENITAL SYSTEMIC VEIN ANOMALIES

Anatomic Imaging Problem* Possible Congenital Diagnosis To Confirm, Look for
No inferior vena cava present in subcostal views. Only hepatic veins are seen. Interrupted inferior vena cava with azygos vein continuation.
• Dilated azygos vein—large venous channel just lateral to the vertebral body.
• Prominent flow in the SVC.
• Dilated azygos arch, located and connecting posterior to the SVC

.

Azygos arch, as it connects to the SVC, appears dilated or flow appears prominent. Coronary sinus appears dilated. Persistent LSVC draining to coronary sinus.
• Suprasternal notch view, aligned along left clavicle—search for a vertical vein than drains from head-to-foot.
• Left parasternal window with marker at 12 o’clock should show a LSVC in its long axis.

No centrally located innominate vein present in suprasternal notch, and coronary sinus appears dilated. Bilateral superior vena cavae without a bridging innominate vein. The presence of a normal right-sided SVC connection and persistent LSVC (see above). Innominate vein or left subclavian vein appears absent, or is not seen in the expected location. Retroaortic innominate vein. In the long axis aortic arch view, look for a vessel in short axis, located just above the RPA.

* Acquired venous anomalies such as deep vein thrombosis should always be considered if these anomalies are present.

image

Figure 9-7 Transverse abdominal view of a patient with interrupted IVC with azygos continuation to the superior vena cava (SVC). The long arrow shows a midline abdominal aorta, and the short arrow shows a dilated azygos vein as it courses just laterally to the vertebral body.

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Figure 9-8 High right parasternal view of the SVC and dilated azygos arch (arrow). Such an appearance should raise the index of suspicion for an interrupted IVC or PAPVC.

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Figure 9-9 A, Suprasternal notch view showing two vessels located underneath the aortic arch: a retroaortic innominate vein (long arrow) and the right pulmonary artery (short arrow). B, Suprasternal notch view with the dot of the transducer positioned at the 3 o’clock position. The arrow indicates the off-screen location of the left subclavian vein. It continues to run below and posterior to the aorta as a retroaortic innominate vein (asterisk).

Physiologic Data

• Isolated systemic venous anomalies are almost always asymptomatic and require no intervention.

• The CS septum should be evaluated for any defects.
• Interrupted IVC or persistent LSVC is sometimes found incidentally, for example, when a central venous catheter is placed and takes an unexpected course.

• Estimation of pulmonary artery (PA) pressures and right ventricular performance is an important element for both pre- and postoperative assessment of either partial anomalous pulmonary venous connection (PAPVC) or TAPVC.
• In unrepaired TAPVC, pulmonary hypertension (PHTN) should prompt the search for a PV obstruction or a restrictive patent foramen ovale.

• For infracardiac, obstruction usually occurs within the liver or where the vertical vein crosses the diaphragm.
• For supracardiac, obstruction occurs usually when the vein crosses between the left mainstem bronchus and the left pulmonary artery.
• Doppler imaging, including pulsed wave and color maps, demonstrates a continuous flow pattern. The usual phasic pattern or venous respiratory variations are not present.

• In repaired anomalous connections, PV stenosis is the most common late complication that requires reintervention or reoperation. To evaluate for vein stenosis, the mean gradient should be estimated by using spectral Doppler averaged over at least two cardiac cycles. Mean gradients of 3 mm Hg or more are a sign of significant stenosis. Peak velocities and maximum instantaneous gradients are less useful and have no applicable clinical correlates.

• In repaired scimitar syndrome, the repaired area is best viewed by imaging the IVC in its long axis (Fig. 9-10). The atrial end of the repaired scimitar vein baffle can typically be located as a “vessel” parallel to the IVC.

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Figure 9-10 A, Oblique parasternal short axis view of all four cardiac chambers. The IVC (short arrow) is shown partially in its long axis to show the parallel course of a patient’s scimitar repair. The course of the pulmonary venous baffle (long arrow) is seen as it empties to the LA. B, Aliased color map of the left atrial end of the baffle. Mean gradient in this patient was estimated to be 3 mm Hg.

Alternate Approaches

• Alternate imaging should be strongly considered when there is unexplained right atrial or right ventricular dilation, or upper-to-lower systemic vein size discrepancy. In addition, an alternate imaging modality should be used when PV anatomy is not completely demonstrated by TTE.

• In patients with poor acoustic windows, TTE may not identify all PV connections.
• Magnetic resonance (MR) angiography or computed tomography (CT) angiography can reliably resolve pulmonary venous anatomy.
• Transesophageal echocardiography (TEE) is also a useful alternate, but is limited to visualizing the proximal venous connections to the RA and LA. It is unlikely that TEE would be able to directly visualize anomalous connections unless they occur at the cardiac level.

• CT angiography or MR angiography can be used when TTE windows are limited or if additional visualization of systemic venous pathways is required.
• Cardiac catheterization can be considered in unrepaired and repaired patients, especially when there is concern for restenosis.

Key Points

• Abnormal systemic venous connections such as persistent LSVC are usually benign and have no hemodynamic impact.

• An exception is the presence of a CS septal defect, which creates an intracardiac right-to-left shunt.

• Anomalous pulmonary venous connections should be included in the differential diagnosis whenever there is unexpected right atrial and right ventricular dilation and/or if there is unexplained dilation of the systemic veins.
• Large-volume right-to-left shunts across the atrial septum should increase the suspicion for TAPVCs.
• Traditional echocardiography can typically result in complete identification of normal pulmonary venous connections in younger, smaller patients, but may be more challenging in larger patients.
• If TTE is unable to resolve anatomic questions, alternate imaging modalities such as cardiac MR imaging or CT can more definitively identify anomalous connections.
• Approximately 11% of patients who undergo TAPVC repair require reintervention for PV stenosis.

Suggested Reading

1 Fulton DR. Partial anomalous pulmonary venous connection. In: Basow Ds, eds. UpToDate. Waltham, MA, 2010.

More detailed review of this condition.

2 Vida VL, Padalino MA, Boccuzzo G, et al. Scimitar syndrome: a European Congenital Heart Surgeons Association (ECHSA) multicentric study. Circulation. 2010;122:1159.

Large series of patients in Europe. Given the low prevalence of this disease, multicenter studies produce the most useful information.

3 Alsoufi B, Cai S, Van Arsdell GS, et al. Outcomes after surgical treatment of children with partial anomalous pulmonary venous connection. Ann Thorac Surg. 2007;84:2020.

4 Seale AN, Uemura H, Webber SA, et al. Total anomalous pulmonary venous connection: morphology and outcome from an international population-based study. Circulation. 2010;122:2718-2726.

Perhaps the largest cohort of patients, which was gathered across 19 centers in Europe.

5 Saxena A, Fong L, Lamb R, et al. Cardiac arrhythmias after surgical correction of total anomalous pulmonary venous connection: late follow-up. Pediatr Cardiol. 1991;12:89.

6 Soriano BD. Total anomalous pulmonary venous connection. In: Basow, Ds, eds. UpToDate. Waltham, MA, 2010.

7 Tanel R, Kirshbom P, Paridon S, et al. Long-term noninvasive arrhythmia assessment after total anomalous pulmonary venous connection repair. Am Heart J. 2007;153:267.

Important series that documents that a high proportion of these patients have arrhythmias.

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