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 Table of Contents  
FOCUS ISSUE - CONGENITAL HEART DISEASE
Year : 2020  |  Volume : 4  |  Issue : 3  |  Page : 332-343

Pulmonary Venous Anomalies: Evaluation by Echocardiography


Department of Pediatrics, LLRM Medical College, Meerut, Uttar Pradesh, India

Date of Submission20-Aug-2020
Date of Acceptance02-Oct-2020
Date of Web Publication18-Dec-2020

Correspondence Address:
Dr. Munesh Tomar
Department of Pediatrics, LLRM Medical College, Meerut - 250 004, Uttar Pradesh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jiae.jiae_53_20

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  Abstract 

Congenital anomalies of pulmonary veins vary widely in anatomic spectrum. Depending on anatomic spectrum, clinical presentation varies from being asymptomatic with incidental diagnosis to critical presentation in neonatal period. Echocardiography plays a very crucial role in defining these lesions and planning for surgical intervention. Additional imaging modalities such as cardiac catheterization, computerized tomographic pulmonary angiography, cardiac magnetic resonance imaging, or cardiac catheterization are needed in a very selective group of patients.

Keywords: Echocardiography, partial anomalous pulmonary venous connection, pulmonary venous anomalies, scimitar syndrome, total anomalous pulmonary venous connection


How to cite this article:
Tomar M. Pulmonary Venous Anomalies: Evaluation by Echocardiography. J Indian Acad Echocardiogr Cardiovasc Imaging 2020;4:332-43

How to cite this URL:
Tomar M. Pulmonary Venous Anomalies: Evaluation by Echocardiography. J Indian Acad Echocardiogr Cardiovasc Imaging [serial online] 2020 [cited 2021 Jan 19];4:332-43. Available from: https://www.jiaecho.org/text.asp?2020/4/3/332/303944


  Introduction Top


Pulmonary vein anomalies vary widely in their anatomic spectrum and clinical presentation. Normally, there are four pulmonary veins carrying oxygenated blood, two from each lung, joining left and right aspect of the posterior surface of the left atrium. In anatomic terms, pulmonary venous anomalies can be classified as follows:

  1. Abnormal numbers
  2. Anomalous connection (partial or total)
  3. Anomalous drainage (partial or total)
  4. Pulmonary vein (s) stenosis including cor triatriatum.


In this article, I am discussing echocardiography evaluation of pulmonary veins and anomalies related to them.


  Echocardiographic Evaluation of Pulmonary Veins Top


Views: Complete delineation of pulmonary veins requires use of multiple views

  1. The subcostal views – The coronal section clearly demonstrates the right upper and left upper pulmonary venous connection to left atrium [Figure 1]a and [Figure 1]b, whereas sagittal section clearly identifies the right upper and right lower pulmonary veins (RLPV) joining the left atrium [Figure 2]a and [Figure 2]b
  2. Apical four-chamber view – This view gives a clear visualization of the left-sided pulmonary veins and right upper pulmonary vein [Figure 3]a and [Figure 3]b. Posterior tilt in apical four-chamber view at the level of inferior vena cava (IVC) shows RLPV connection to left atrium
  3. Parasternal short- and long-axis views – Parasternal short-axis view shows both left pulmonary veins and right upper pulmonary vein joining left atrium [Figure 4]a and [Figure 4]b, whereas left and right-sided pulmonary veins can be shown in parasternal long-axis view joining left atrium. Descending thoracic aorta in short-axis separates right and left-sided in pulmonary veins in paratsernal long axis view [Figure 5]a and [Figure 5]b
  4. Suprasternal short-axis view – Also called “spider view” or “crab sign.” This is the best view to demonstrate all four pulmonary veins joining left atrium in small babies with good echo windows [Figure 6].
Figure 1: Subcostal coronal view showing right and left upper pulmonary venous connection to left atrium (arrows) on two-dimensional (a) and color flow mapping (b). RUPV: Right upper pulmonary vein, LUPV: Left upper pulmonary vein, LA: Left atrium, RA: Right atrium

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Figure 2: Subcostal sagittal view showing right upper and lower pulmonary venous connection to left atrium (arrows) on two-dimensional (a) and color flow imaging (b). RUPV: Right upper pulmonary vein, LLPV: Left lower pulmonary vein, LA: Left atrium, RA: Right atrium, IVC: Inferior vena cava

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Figure 3: Apical four-chamber view showing left lower pulmonary vein and right upper pulmonary vein connecting to left atrium on two-dimensional (a) and color flow mapping (b). Color flow shows turbulent flow in let lower pulmonary vein suggestive of obstruction. RUPV: Right upper pulmonary vein, LLPV: Left lower pulmonary vein, LA: Left atrium, RA: Right atrium, LV: Left ventricle, RV: Right ventricle

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Figure 4: Parasternal short-axis view with color flow mapping showing (a) left upper and right upper pulmonary vein connecting to left atrium (b) both left pulmonary veins connecting to left atrium. RUPV: Right upper pulmonary vein, LUPV: Left upper pulmonary vein, LA: Left atrium, Ao: Aorta

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Figure 5: Parasternal long-axis view showing left and right pulmonary veins connecting to left atrium with descending aorta (white star) in short axis separating left and right pulmonary veins on two-dimensional (a) and color flow mapping (b). RPV: Right pulmonary vein, LPV: Left pulmonary vein, LA: Left atrium, LV: Left ventricle, Ao: Aorta, RV: Right ventricle

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Figure 6: Suprasternal short-axis view showing all four pulmonary veins connecting to left atrium (arrows). Transverse arch is seen in short axis (Ao). RUPV: Right upper pulmonary vein, RLPV: Right lower pulmonary vein, LUPV: Left upper pulmonary vein, LLPV: Left lower pulmonary vein, LA: Left atrium, Ao: Aorta

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Doppler interrogation of pulmonary veins

All pulmonary veins should be interrogated by color flow mapping followed by pulsed and continuous wave Doppler. Proper attention should be given to intercept angle, wall filter, and velocity scale. Pulsed Doppler sample should be placed 1–2 cm into the orifice of the pulmonary vein as it enters the left atrium, so that Doppler velocity reflects the events occurring in pulmonary vein and not the left atrium. In normal subjects, the pulmonary venous Doppler recording consists of biphasic forward flow, “S” wave in systole due to atrial relaxation and descent of floor of left atrium, “D” wave in diastole due to fall in left atrium pressures as opening of mitral valve and rapid ventricular filling, small reversal “A” wave occur with left atrial contraction [Figure 7].
Figure 7: Pulse Doppler interrogation of pulmonary vein showing normal phasic flow pattern. “S” and “D” are antegrade flow and small “A” wave of retrograde flow. Doppler signal recoded from left lower pulmonary vein. S: Systole, D: Diastole

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The normal values for the S, D, and A waves in subjects under the age of 50 years are nearly constant, except in newborn and found to have nearly equal S and D wave (0.48 ± 0.09 and 0.50 ± 0.10 m/s, respectively) and small peak A velocity 0.19 ± 0.04 m/s). Over the age of 50 years, the peak “S” velocity (0.71 ± 0.09 m/s) is considerably higher than peak “D” velocity (0.38 ± 0.09) and the peak of “A” velocity is higher (0.23 ± 0.14).[1],[2]

In the newborn, significant changes in the peak velocities occur in the first 96 h after birth.[3] At one hour of birth, pulmonary vein Doppler reveals continuous, high-velocity flow with peak S velocity of 0.73 ± 0.23 m/s and peak D velocity of 0.81 ± 0.19 m/s. At one hour of birth, a significant fall in the peak S and D velocities occur. This continuous high velocity pattern present in pulmonary veins in first few days of life may be due to relatively hypoplastic and under perfused pulmonary veins during fetal life, which suddenly exposed to increased pulmonary blood flow after birth with fall in pulmonary vascular resistance.

Variables affecting pulmonary venous flow to left atrium are as follows:

  • Left atrial pressure
  • Left atrial compliance
  • Mitral regurgitation
  • Atrial arrhythmia.


Pulmonary venous Doppler pattern reflects left atrial activity, so in case of anomalously connecting pulmonary vein(s), pulmonary venous flow pattern will not follow normal pattern [Figure 8]. Doppler pattern will be continuous flow of low velocity (high velocity in case of obstruction).
Figure 8: Pulse Doppler interrogation of pulmonary venous confluence in case of TAPVC to coronary sinus. Doppler shows low velocity continuous flow with no specific waveform. TAPVC: Total anomalous pulmonary venous connection

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Anomalies of pulmonary veins

Abnormal number of pulmonary veins

Normally, there are two right and two left pulmonary veins. The most common variation is the presence of single pulmonary vein on either left or right side.[4] There may be increased number of pulmonary veins. The number of pulmonary veins on one side is reported from three to five.[5] The variation in the number of pulmonary veins is of no clinical significance if they are connected normally to left atrium.

Anomalous pulmonary venous return

One or more of the pulmonary veins may connect anomalously to systemic venous system. Partial anomalous pulmonary venous connection (PAPVC) is used to describe the condition where one or more but not all pulmonary veins connect abnormally and total anomalous pulmonary venous connection (TAPVC) is a term used when all four pulmonary veins connect abnormally. When pulmonary veins are connected normally to left atrium but drain anomalously then depending on the number of pulmonary veins, the condition is termed as partial anomalous pulmonary venous drainage or total anomalous pulmonary venous drainage. While assessing the morphology of anomalous pulmonary connections, several features are important:

  1. What proportion of the pulmonary venous drainage is connected to sites other than morphologically left atrium (partial or total anomalous connection)?
  2. Do all veins draining anomalously connected to the same site?
  3. Where is the site, or sites, of drainage?
  4. Is there a stenotic area or region at some point along the route of anomalous drainage?
  5. Is the anomalous pulmonary venous connection an isolated malformation or is it part of a more complex anomaly?
  6. Cardiac hemodynamics as chamber dilatation, ventricular function, and pulmonary artery (PA) pressure.



  Total Anomalous Pulmonary Venous Connection Top


In 1798, Wilson described a “monstrous formation of the heart in which the superior caval vein was joined by a trunk formed by two large veins coming out of the lungs.”[6] Later, the entity is termed as “total anomalous pulmonary venous connection.” Total anomalous pulmonary venous connection (TAPVC) is defined as all pulmonary veins forming confluence and anomalously connecting to systemic venous circulation (superior vena cava, coronary sinus, directly to right atrium (RA), IVC, or a combination of these). The only source of the blood flow to the left side is through interatrial communication (patent foramen ovale/atrial septal defect). TAPVC frequently occurs as an isolated lesion, but may be associated with other more complex cardiac defects as heterotaxy syndrome with asplenia.

Complex form of TAPVC occurs wherein the four pulmonary veins do not form a confluence but drain to different systemic venous sites. These are called as mixed TAPVC.

TAPVC comprised 1.5% of all patients with cardiovascular malformations and occurred once in 14,700 livebirth.[7] In the New England Regional Infant Cardiac Program, two-third of the supracardiac and cardiac TAPVC had been reported in males, while infradiaphragmatic TAPVC has equal distribution in males and females.[8]

Site of drainage of pulmonary venous confluence (PVC) in TAPVC:[9],[10]

  1. Supracardiac


    1. Left innominate vein (26%–36%)
    2. Right superior vena cava (11%–15%).


  2. Cardiac


    1. Coronary sinus (1%–16%)
    2. RA (8%–15%).


  3. Infracardiac (portal system) (13%–24%)
  4. Mixed type (5%–7%).


Each type can be obstructed or nonobstructed. If obstructed, site of obstruction could be:

  1. Venous channel
  2. At the site of venous confluence to systemic venous junction
  3. Restrictive interatrial communication
  4. Individual pulmonary vein(s).


It is imperative that all neonates diagnosed as primary pulmonary arterial hypertension in the neonatal intensive care unit should have a very strong suspicion of infradiaphragmatic TAPVC.

The role of echocardiography in the diagnosis of TAPVC is as follows:

  • To define individual pulmonary vein
  • To ascertain that all pulmonary veins are draining to PVC or to ascertain each pulmonary vein connecting to systemic vein as in case of mixed TAPVC
  • Relation of PVC to left atrium, pulmonary artery (PA), and airways
  • Site of drainage of PVC
  • Any evidence of obstruction
  • Adequacy of interatrial communication
  • Any associated heart defect
  • Hemodynamic effects as PA pressure and ventricular function.


A complete step-by-step approach with use of two-dimensional echocardiography, color flow, and pulse and continuous Doppler interrogation can fulfill these goals. One should try to profile pulmonary venous anatomy from multiple views. In recent year with introduction of broadband transducers, the detailed diagnosis of anomalous pulmonary venous connection can be made with high degree of accuracy eliminating the need of cardiac catheterization or computed tomography and pulmonary angiography (CTPA) for majority of patients undergoing surgery. Main indication for CTPA is in case of mixed TAPVC to look for all sites of anomalous connections of pulmonary veins. Cardiac catheterization is mainly indicated in case of late presentation that needs hemodynamic assessment and in case of associated complex congenital cardiac defects.


  Steps in Diagnosis of Total Anomalous Pulmonary Venous Connection Top


The features common to all form of total anomalous pulmonary venous connection are

  • Bald left atrium: Inability to image the pulmonary vein entrance to left atrium is the first echocardiographic suspicion that supports the diagnosis of TAPVC [Figure 9]
  • Dilated right-sided structures (RA, right ventricle, and PA) [Figure 10]a
  • Interatrial septum bows toward the left, with right to left shunt at atrial level [Figure 9] and [Figure 10]a
  • Right ventricle appears to compress the left ventricle. M-mode of the ventricles from parasternal long-axis view shows paradoxical septal motion in diastole due to of RV volume overload [Figure 11]a and [Figure 11]b
  • There may be echocardiographic evidence of pulmonary hypertension [Figure 10]b and [Figure 10]c.
Figure 9: Subcostal sagittal view showing dilated right atrium and interatrial septum bowing to left atrium, with interatrial communication shunting right to left (white arrow). Bulging of interatrial septum suggestive of restrictive interatrial communication. LA: Left atrium, SVC: Superior vena cava, RA: Right atrium

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Figure 10: (a) Apical four-chamber view showing dilated RA and ventricle. Interatrial septum bowing to left due to high right atrial pressure. (b) Same view with color flow mapping showing moderate TR along with dilated RA and ventricle. Left atrium is bald, not receiving any pulmonary vein. (c) Continuous wave Doppler interrogation of TR giving TR peak velocity of 456 cm/s (peak gradient 83 mmHg) indicating severe pulmonary arterial hypertension. LA: Left atrium, LV: Left ventricle RA: Right atrium, RV: Right ventricle, TR: Tricuspid regurgitation

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Figure 11: (a) M-mode of ventricles from parasternal long-axis view showing significantly dilated right ventricle, paradoxical motion of ventricular septum in systole due to severe PAH. Small PE is seen in systole. (b) Parasternal short-axis view showing grossly dilated right ventricle and crescentic left ventricle due to severe PAH and paradoxical septal motion. RV: Right ventricle, LV: Left ventricle, PE: Pericardial effusion, PAH: Pulmonary arterial hypertension

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Pulmonary venous confluence

PVC is a common chamber, in which all pulmonary veins connect and finally drain to systemic venous channel. PVC is defined as an echo-free space, which lies in the posterior plane to left atrium, but it is separated from it. Subcostal coronal view is the best view to profile PVC and its relation to left atrium [Figure 12]. In subcostal sagittal view, PVC is seen in its cross-section below the right PA and posterior to the superior vena cava giving appearance of double circle [Figure 13]. The size and orientation (horizontal and vertical) of PVC and its relation to left atrium is important when planning for surgery.
Figure 12: Subcostal coronal view in posterior plane showing PVC receiving pulmonary veins from both side in case of TAPVC to azygos vein. PVC is closely related to posterosuperior surface of left atrium. Arrow points to the beginning of vertical vein. RA: Right atrium, LA: Left atrium, RV: Right ventricle, LV: Left ventricle, RPA: Right pulmonary artery, PVC: Pulmonary venous confluence, TAPVC: Total anomalous pulmonary venous connection

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Figure 13: Subcostal sagittal view showing double circle posterior to superior vena cava, one formed by pulmonary venous confluence (white star) and another formed by right pulmonary artery (white arrow), both in short axis. SVC: Superior vena cava, RA: Right atrium

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III. After identifying the PVC, the next step is to image individual pulmonary vein for course and diameter. The size of individual pulmonary vein at the time of initial diagnosis is the strong independent predictor of survival in TAPVC.[11]

Orientation and site of drainage of pulmonary venous confluence

  • In supracardiac TAPVC (to innominate vein/superior vena cava/azygos vein), the PVC lays posterior and superior to left atrium vertically oriented. This can be best visualized in modified parasternal short-axis, suprasternal short-axis, and subcostal sagittal views. Suprasternal short-axis view in supracardiac TAPVC to left innominate vein shows the ascending venous channel connecting to left innominate vein [Figure 14]a, [Figure 14]b and [Figure 15]a, [Figure 15]b. In this view, the anomalous pulmonary venous connection gives the appearance of large vascular collar surrounding the transverse arch. The color flow signal in vertical vein shows continuous low velocity flow directed away from the heart. The systemic vein (left superior vena cava) in this view has flow directed toward the heart. There will be evidence of dilated innominate vein and superior vena cava along with dilated right-sided cardiac chambers
  • In case of TAPVC to superior vena cava, the innominate vein will be of normal caliber, and from the point of joining of PVC, the superior vena cava will be grossly dilated. The vertical vein is seen on the right side joining the superior vena cava (SVC) [Figure 16]a and [Figure 16]b
  • A rare variety of TAPVC is to azygos vein, the channel ascends posterior to right PA and joins the azygos vein.[12] SVC will be dilated beyond the point of joining azygos vein. The best view to define this anatomy is subcostal sagittal, high right parasternal short-axis, and suprasternal short-axis views [Figure 17]a and [Figure 17]b
  • In case of TAPVC to coronary sinus, the PVC lies directly posterior to left atrium and all four pulmonary veins join ipsilaterally to that confluence at the same level. Subcostal coronal, apical four-chamber, and parasternal long-axis views clearly define the dilated coronary sinus receiving all pulmonary veins, which bulges anterosuperiorly into left atrium [Figure 18]a,[Figure 18]b,[Figure 18]c. TAPVC to coronary sinus is mistaken as ostium primum ASD with large left to right shunt from subcostal coronal and apical four-chamber view because coronary sinus opening mistaken as ostium primum ASD. Surgical anastomosis of this PVC to posterior wall of left atrium is relatively easy
  • In case of TAPVC to RA, the PVC can be imaged draining directly to RA. The views most commonly used are subcostal coronal, subcostal sagittal, and parasternal short-axis views [Figure 19]a and [Figure 19]b.
  • In infracardiac TAPVC (to IVC/hepatoportal system), the pulmonary veins connect to vertical vein at different levels and the repair is more challenging. The PVCs is often small, inferior, and posterior to left atrium and descends and passes through the diaphragm usually anterior to aorta and join the systemic vein and hepatoportal system (portal vein, ductus venosus, left hepatic vein, and IVC). Subcostal sagittal view is the best view to define origin of the PVC and its course and connection to hepatoportal system [Figure 20]a and [Figure 20]b. Three channels, two descending (aorta and the PVC) and one ascending (IVC which is dilated), can be defined. Pulse Doppler interrogation of descending venous channels show systolic flow in aorta and continuous flow in PVC. Subcostal short-axis view shows these three vessels in short axis [Figure 20]c
  • Rarely mixed form of TAPVC occurs, in which pulmonary veins drain to two or more separate systemic venous sites. In this subgroup, multiple windows using two-dimensional and color Doppler flow must be used to image the connection of all four individual pulmonary veins. The most common type of mixed TAPVC is pulmonary vein connection to coronary sinus and via vertical vein to left innominate vein
  • Dual connection: A rare variety where PVC receives all pulmonary veins but the confluence is connected to more than one site. The most common reported pattern is TAPVC to coronary sinus and vertical vein to innominate vein [Figure 21]a and [Figure 21]b.[13]
Figure 14: Suprasternal short-axis view showing VV in case of TAPVC to innominate vein. (a) On two-dimensional imaging. Note the dilated innominate vein and SVC. (b) On color flow mapping the vertical vein (red flow) is joining the innominate vein. Flow pattern is laminar in the vertical vein (nonobstructed). VV: Vertical vein, Inn vein: Innominate vein, TAPVC: Total anomalous pulmonary venous connection

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Figure 15: Suprasternal short-axis view in another patient with TAPVC to vertical vein to innominate vein (a) color flow mapping showing turbulent flow. Vertical vein is obstructed as it passes between pulmonary artery and bronchus. (b) Doppler interrogation of vertical vein shows continuous flow across, a feature of obstruction. TAPVC: Total anomalous pulmonary venous connection

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Figure 16: Echocardiography of a child with TAPVC to SVC. (a) High right parasternal vein shows ascending venous channel on right with turbulence at the distal end as it turn to join SVC (arrow). (b) Suprasternal short-axis view showing turbulent flow of vertical vein (arrow) joining SVC. VV: Vertical vien, SVC: Superior vena cava, TAPVC: Total anomalous pulmonary venous connection

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Figure 17: Total anomalous pulmonary connection to azygos vein. (a) Subcostal sagittal view on color flow mapping showing ascending channel from pulmonary venous confluence posterior to right pulmonary artery to join azygos vein (red channel-white arrow). (b) Suprasternal short-axis modified view on color flow mapping showing ascending pulmonary venous confluence joining azygos vein (blue channel-white arrow). LA: Left atrium, RA: Right atrium, SVC: Superior vena cava

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Figure 18: Echocardiography of an infant with TAPVC to CS. (a) Modified subcostal sagittal view in showing dilated coronary sinus receiving pulmonary veins from both sides (arrows). Note dilated right atrium. (b) Subcostal coronal view on two dimensional imaging showing dilated coronary sinus. In this view opening of dilated coronary sinus mistaken and reported as ostium primum atrial septal defect and with color flow reported as left to right shunt. (c) On color flow mapping showing pulmonary venous confluence joining coronary sinus. RV: Right ventricle, LV: Left ventricle, CS: Coronary sinus, TAPVC: Total anomalous pulmonary venous connection

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Figure 19: Echocardiography of an infant with TAPVC to RA (subcostal coronal view) (a) Two-dimensional showing pulmonary venous confluence posterosuperior to left atrium and joining RA (b) Color flow mapping showing pulmonary venous confluence joining RA. PVC: Pulmonary venous confluence, LA: Left atrium, RA: Right atrium, LV: Left ventricle

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Figure 20: Echocardiography of a neonate with infradiaphragmatic TAPVC. (a) Subcostal sagittal view on two-dimensional echocardiography showing venous channel (PVC) anterior to descending Ao. (b) Same view with color flow mapping showing descending pulmonary venous confluence anterior to descending aorta and joining hepatoportal system. There is turbulence flow (arrow) at site of joining the hepatoportal system suggestive of obstructed flow. (c) Subcostal short-axis view showing three vessels, IVC, descending aorta and PVC, in short axis in case of infradiaphragmatic TAPVC. Ao: Aorta, PVC: Pulmonary venous confluence

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Figure 21: Echocardiography of an infant with mixed TAPVC. (a) Subcostal coronal view showing PVC joining dilated coronary sinus. There is turbulence at the junction of confluence to coronary sinus suggestive of some obstruction. (b) Suprasternal short-axis view showing LUPV joining innominate vein. SVC: Superior vena cava, RA: Right atrium, CS: Coronary sinus, LUPV: Left upper pulmonary vein, PVC: Pulmonary venous confluence

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Defining the obstruction

The color Doppler flow mapping and pulse wave Doppler should be used to diagnose the presence of obstruction. Normal flow pattern is laminar flow on color flow mapping and biphasic low velocity on pulse Doppler. If there is obstruction at any level, there will be turbulent, aliased flow on color Doppler flow mapping, and high velocity disturbed flow on pulse Doppler. The level of obstruction can be as follows:

  • Long channel itself offers some resistance
  • Restrictive interatrial communication [Figure 9]
  • In supracardiac TAPVC to left innominate vein, as ascending channel passes between left PA and left bronchi [Figure 15]a and [Figure 15]b.
  • At junction of venous confluence to the site of drainage [Figure 16] and [Figure 21]
  • In infradiaphragmatic TAPVC [Figure 20]a and [Figure 20]b


    • As channel passes through the diaphragm
    • Narrow long channel
    • Resistance offered by hepatoportal system


Associated cardiac anomalies

TAPVC is usually an isolated anomaly in the setting of visceral situs solitus with levocardia. However, it has been reported with a number of cardiac defects as transposition of great vessels, tetralogy of Fallot, single ventricle, left-sided obstructive lesions, ventricular septal defect, and hypoplastic left heart syndrome.[14]

Management

TAPVC is a surgical entity and elective surgical correction (rerouting of PVC to left atrium) at the time of diagnosis is indicated. Emergency surgery is advised in case of obstructed TAPVC.


  Partial Anomalous Pulmonary Venous Connection Top


PAPVC is the condition when one or more, but not all, pulmonary vein (s) connect anomalously to systemic vein. Almost every possible connection between pulmonary vein on the one hand and various systemic venous tributaries on the other hand has been reported. Usually, left-sided pulmonary veins connect anomalously to the derivatives of left cardinal system, i.e., coronary sinus and the left innominate vein. Right-sided pulmonary veins usually connect to derivatives of the right cardinal system, i.e., superior vena cava or IVC.

PAPVC is usually associated with atrial septal defect, and in only 20% of cases, atrial septum is intact. Other associated heart defects can be ventricular septal defect, left superior vena cava, and complex congenital heart defects associated with isomerism. If one excludes PAPVC associated with sinus venosus atrial septal defect (which is anomalous drainage with normal connecting pulmonary veins), the most common type of PAPVC is to left innominate vein, followed by right pulmonary veins to IVC (scimitar syndrome).

Scimitar syndrome

The scimitar syndrome is characterized by dextrocardia, hypoplasia of the right PA, underdevelopment of the right lung, abnormal connection of the right pulmonary veins (usually lower and middle) to the IVC – right atrial junction (giving the scimitar appearance on the frontal chest radiograph), and anomalous systemic arterial supply to the right lung (lung sequestration), often its basal segments.

First described by Cooper and Chassinat in 1836[14] but not using the terms “scimitar,” it was Halasz et al.[15] fully characterized the syndrome now known as the “scimitar” syndrome.

Causes of pulmonary arterial hypertension in scimitar

PAH in these patients may reflect several etiologies, including anomalous systemic arterial supply, pulmonary venous obstruction, redistribution of flow to the unaffected lung, associated cardiac malformations, or combinations of these factors.[16],[17],[18],[19]

Partial anomalous pulmonary venous connection – Role of echocardiography

While doing echocardiography, high index of suspicion is required to diagnose PAPVC. On two-dimensional echocardiography and color flow mapping, all pulmonary veins should be defined connecting to left atrium and all possible sites should be sought with color flow as in case of supernumerary pulmonary vein. One can profile four pulmonary veins connecting to left atrium, but accessory pulmonary vein may be seen draining anomalously.

Combination of multiple views, subcostal, apical four-chamber, parasternal, and suprasternal, should be used to define pulmonary venous connection [Figure 22]a, [Figure 22]b and [Figure 23].
Figure 22: Subcostal sagittal view showing SVC connecting to RA (a). Modified subcostal sagittal view showing RUPV to RA (b). RA: Right atrium, LA: Left atrium, RUPV: Right upper pulmonary veins, SVC: Superior vena cava

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Figure 23: Supratsernal view showing isolated left upper pulmonary vein to innominate vein. Inn V: Innominate vein, LUPV: Left upper pulmonary vein, Ao: Aorta

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In case of scimitar syndrome, one requires high index of suspicion on the basis of clinical presentation, chest X-ray showing “scimitar sign” and pulmonary arterial hypertension on echocardiography. Subcostal sagittal view with color flow mapping shows right-sided descending pulmonary venous channel (usually formed by right middle and lower pulmonary veins) joining IVC [Figure 24]a and [Figure 24]b. Site of anastomosis is more commonly infradiaphragmatic, but could be just above the diaphragm. Doppler interrogation shows turbulent flow due to obstruction. Descending aorta should be interrogated for collaterals on color flow from subcostal sagittal view with transducer tilted toward the left.
Figure 24: (a and b) Subcostal coronal view (inverted) in a child with scimitar syndrome. Two-dimensional echocardiography and color flow mapping showing RLPV joining IVC. IVC: Inferior vena cava, RLPV: Right lower pulmonary vein

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Right atrial and ventricle volume overload depends on the number of anomalously draining pulmonary veins, and in majority of cases with PAPVC, there will be evidence of right-sided volume overload, except in case of anomalous connection of single pulmonary vein where pulmonary blood flow is not significantly increased. Evidence of RA and RV volume overload in the absence of ASD should prompt a careful search for PAPVC.

Management

If there is evidence of right heart volume overload, pulmonary veins should be rerouted to left atrium. Isolated single pulmonary vein connecting anomalously usually does not require any surgical intervention.

Treatment for scimitar syndrome requires individualized approach because there are multiple factors affecting outcome. CTPA and cardiac catheterization is needed in all patients to look for anomalously connecting right-sided pulmonary veins, lung volume, lung malformation (Horse-shoe lung), lung sequestration, and collateral from descending aorta. Coiling of collateral is needed before surgical rerouting of pulmonary vein (s) to left atrium and correction of associated structural defect.


  Anomalous Drainage of Pulmonary Veins with Normal Connection Top


There are two conditions in which pulmonary veins are connected normally to posterior wall of left atrium, but flow is directed to RA. These conditions are as follows:

  • Sinus venosus atrial septal defect (described in the chapter of ASD)
  • Septum primum malposition defect.


Septum primum malposition defect causing partial or total anomalous pulmonary venous drainage

This is a rare entity, which was first observed by Edwards in 1953[5] and later described by Moller et al. in 1967.[20] This condition is usually associated with visceral heterotaxy, commonly left isomerism and rarely with right isomerism.

Echocardiographic pointers to the diagnosis of septum primum malposition defect are as follows:[21]

  • Deviation of septum primum toward the anatomical left atrium
  • Absence of septum secundum
  • Normally attached pulmonary veins to anatomic left atrium
  • Interatrial communication in most posterior plane between posterior wall of LA and displaced septum primum
  • Color flow mapping shows drainage of pulmonary veins to anatomical right atrium. The number of anomalous pulmonary venous drainage to right atrium depends on the degree of malposition of septum primum.


The views that can profile these anomalies are subcostal coronal, apical four-chamber, and parasternal long axis [Figure 25]a and [Figure 25]b.
Figure 25: Subcostal coronal view of an infant with total anomalous pulmonary venous drainage due to malalignment of septum primum. (a) Two dimensional echocardiography shows malalignment of septum primum to left causing drainage of pulmonary veins to right atrium. (b) Same view with color flow mapping showing anomalously draining pulmonary veins to right atrium. RV: Right ventricle, LV: Left ventricle, RUPV: Right upper pulmonary vein, LLPV: Left lower pulmonary vein

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Management

Elective surgical intervention to align atrial septum and to direct pulmonary venous flow to left atrium.


  Pulmonary Vein Stenosis with Normal Connection Top


It is a rare anomaly usually associated with other structural heart defects. One or more of the pulmonary veins may be stenosed at the junction with left atrium. The length of the stenosis varies and may extend for a considerable length in extra- and intrapulmonary portion. Three types of stenosis have been reported, discrete stenosis, tubular hypoplasia, and bilateral multiple short pulmonary veins that are hypoplastic for their entire extrapulmonary course.[22],[23] Echocardiography diagnosis is based on high index of suspicion in patients who present with features of unexplained pulmonary arterial hypertension or pulmonary hypertension is out of proportion to the heart defect.

After two-dimensional demonstration of pulmonary venous connection, color flow mapping must be done. On two-dimensional echocardiography, the stenosed pulmonary vein(s) either have long segment hypoplasia or there is discrete stenosis. On color flow mapping, turbulent or mosaic flow pattern is the first indication of pulmonary vein stenosis in contrast to laminar flow in nonobstructed pulmonary vein [Figure 26]a and [Figure 27]a. Pulsed and continuous wave Doppler revealed loss of phasic flow and or increased velocity [Figure 26]b and [Figure 27]b. The change in flow pattern depends on the length of obstructed channel and severity of stenosis. With long-segment stenosis, one may not get increased velocity but loss of phasic flow pattern will be there, while with discrete stenosis, there will be increased velocity associated with or without preservence of phasic pattern. Even with preservence of phasic pattern ,Doppler wave form will not touch the baseline. The condition has to be differentiated from increased pulmonary venous flow velocity associated with large left to right shunt. In that case, there will be increased pulmonary vein velocity with preservence of phasic pattern, which touches the baseline.[24]
Figure 26: Echocardiography in patients with pulmonary vein stenosis. (a) Subcostal coronal view with color flow mapping showing thin jet with turbulent flow in right upper pulmonary vein due to obstructed Pulse Doppler imaging showing continuous pattern in stenosed pulmonary vein. RA: Right atrium, LA: Left atrium, RV: Right ventricle, LV: Left ventricle, RUPV: Right upper pulmonary vein

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Figure 27: (a) Apical four-chamber view showing turbulent flow in left lower pulmonary vein in a patient with complex congenital heart disease with increased pulmonary blood flow. (b) Pulse Doppler interrogation of patient b showing higher velocity phasic flow which is not touching baseline. RA: Right atrium, LA: Left atrium, RV: Right ventricle, LV: Left ventricle, LLPV: Left lower pulmonary vein

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Cor triatriatum

Cor triatriatum is a developmental anomaly of common pulmonary vein with stenosis. Pulmonary veins enter an accessory chamber and the chamber joins left atrium through a narrow opening. This chamber may communicate with RA directly or indirectly by the way of anomalously connecting pulmonary veins.[25] Less commonly, the accessory chamber has no communication with left atrium (atretic opening) and drain to RA directly or indirectly through TAPVC.[26] In case of subtotal cor triatriatum, the accessory chamber receives pulmonary veins from one lung and drain to atrium (left or right), while veins from other lung join directly to left atrium.

Subcostal coronal, apical four-chamber, and parasternal long-axis views define the accessory chamber well. Color flow mapping shows turbulent flow if there is obstruction across communication with left atrium and also to look for communication with RA. Pulmonary venous flow to accessory chamber or directly to left atrium should also be defined by two-dimensional and color flow mapping. Pulse and continuous Doppler interrogation should be used to check for gradient at accessory chamber with left atrial communication site. Less commonly, the communication site is nonobstructive and diagnosed incidentally on echocardiography.

Cor triatriatum and supramitral ring: Both the lesions present with obstruction to mitral inflow due to obstruction caused by a linear structure [Figure 28]a, [Figure 28]b and [Figure 29]a, [Figure 29]b.
Figure 28: Echocardiography of an infant with cor triatriatum. (a) Apical four-chamber view showing membranous partition in the left atrium (arrow). (b) On color flow mapping, turbulence to left ventricle inflow is starting at the level of shelf. RA: Right atrium, LA: Left atrium, RV: Right ventricle, LV: Left ventricle, CC: Common chamber

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Figure 29: Echocardiography of an infant with supramtral ring. (a) Apical four-chamber view showing membrane attached to mitral annulus on left atrial side. (b) Color flow mapping showing turbulence starting at mitral annulus level due to obstruction by supramitral ring. RA: Right atrium, LA: Left atrium, RV: Right ventricle, LV: Left ventricle

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  • The membrane in cor triatriatum is usually curvilinear and may have appearance of wind sock. It moves toward the mitral valve in diastole
  • Supramitral ring is on the atrial surface of the mitral ring and relatively immobile. It moves away from the mitral valve in diastole
  • Membrane in cor triatriatum is proximal to left atrial appendage and foramen ovale, while supramitral ring is distal to left atrial appendage and foramen ovale
  • Pulmonary veins open into the accessory chamber of cor triatriatum, while in case of supramitral ring, pulmonary veins connect normally with left atrium.


Management

Cor triatriatum is a surgical entity and needs surgical correction. Pulmonary venous anatomy should be evaluated carefully while intervening these patients. Usually, there is obstruction to pulmonary venous return to left atrium (pulmonary venous hypertension) and child presents with features of congestive cardiac failure and pulmonary arterial hypertension requiring early surgery.

Isolated pulmonary vein stenosis with hypoplasia has poor outcome after surgical or catheter intervention.


  Echocardiography in Postsurgical Intervention Top


Postsurgical intervention for pulmonary venous anomaly, echocardiography plays a very important role in immediate postoperative period and on follow-up. Points to be looked on echo are as follows:

  1. Site of anastomosis/rerouting should be evaluated by two-dimensional echocardiography, color flow mapping, and Doppler interrogation [Figure 30]a and [Figure 30]b
  2. Interatrial patch for any residual ASD
  3. Ventricular dimensions and function
  4. PA pressure
  5. Pericardial effusion.
Figure 30: Subcostal coronal view of a patient post-TAPVC surgical repair. (a) On color flow mapping, there is turbulent flow at the anastomotic site of pulmonary venous confluence to left atrium. (b) Continuous wave Doppler interrogation showing continuous flow due to obstruction at the anastomotic site. RA: Right atrium, LA: Left atrium, PVC: Pulmonary venous confluence, TAPVC: Total anomalous pulmonary venous connection

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  Conclusion Top


  1. Pulmonary venous anomalies include a wide spectrum of abnormalities
  2. Echocardiography plays a crucial role in defining the anomalies. Pulmonary venous anatomy should be evaluated with the use of multiple echocardiographic views
  3. Any child with features of congestive cardiac failure, pulmonary arterial hypertension and cyanosis, total anomalous pulmonary venous connection should be suspected and careful evaluation by echocardiography should be done
  4. Any neonate with the diagnosis of persistent pulmonary hypertension of neonate, one should have strong suspicion of infradiaphragmatic total anomalous pulmonary venous connection
  5. Unexplained right heart dilatation, partial anomalous pulmonary venous connection should be ruled out. In grown-up patients with poor echo windows, one may require transesophageal echocardiography or computed tomography pulmonary angiography for complete evaluation
  6. In case of unexplained pulmonary arterial hypertension, pulmonary vein stenosis should be ruled out.


Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
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    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11], [Figure 12], [Figure 13], [Figure 14], [Figure 15], [Figure 16], [Figure 17], [Figure 18], [Figure 19], [Figure 20], [Figure 21], [Figure 22], [Figure 23], [Figure 24], [Figure 25], [Figure 26], [Figure 27], [Figure 28], [Figure 29], [Figure 30]



 

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