TOTAL ANOMALOUS PULMONARY VENOUS

CONNECTION

DR VISHWANATH HESARURSENIOR RESIDENT

DEPARTMENT OF CARDIOLOGYJNMC , BELGAUM

DEFINITION

TAPVC defines the anomaly in which the pulmonary veins have no connection with the left atrium. Rather, the pulmonary veins connect directly to one of the systemic veins (TAPVC) or drain in to right atrium.

A PFO or ASD is present essentially in those who survive after birth

HISTORY

Wilson : 1st description - case report in 1798.

Friedlowsky : 1st description of TAPVC in 1868.

Muller : 1st Successful open repair in 1951.

INCIDENCE

0.6 to 1.2 per 10,000 live births

0.7 and 1.5 percent of all CHD

A strong male preponderance of 3:1

  Birth weight was less than 2500 g in 16.2%

Gestational age was less than 38 weeks in 18.9%

Intrauterine growth retardation occurred in 26.8%

68% of these patients were diagnosed as neonates

GENETICS

Mechanism of transmission – Not been elucidated

No known genetic pattern of transmission.

Associated with syndromes most notably Asplenia , Polysplenia .

EMBRYOLOGY

PAPVC results from failure to establish a normal connection between one or more of the pulmonary veins with the CPV before the connections with the splanchnic venous system have regressed.

TAPVC results from failure to establish a normal connection between the pulmonary venous plexus & the CPV before the connections with splanchnic venous system have regressed .

 Atresia of the common pulmonary vein and  cor triatriatum.

CLASSIFICATION OF TAPVC Smiths classification

Neills classification - Based on embryologic basis

Burroughs and Edwards classification

Darlings classification

Smith classification

Supradiaphragmatic Type: Pulmonary veins are connected to: the left innominate vein by the characteristic vertical vein, or the coronary sinus, the right atrium, or the SVC, without pulmonary venous obstruction

Infradiaphragmatic Type: Pulmonary veins drain into the portal vein or hepatic veins, with pulmonary venous obstruction.

Smith et.al. Am J Dis Child 1961;101:41-51

Neills classification

Group having connection to the right atrium or right common cardinal system (SVC and the azygous veins)

Connections to the left common cardinal system(left innominate vein, left SVC or the coronary sinus)

Connections to the umbilicovitelline system (portal vein, ductus venosus or hepatic veins)

Neill CA: Pediatrics 18:880,1956

Burroughs and Edwards classification

Suggested a classification with prognostic implications based on the length of of the anomalous channel (long, intermediate, or short)

However the prognostic implications suggested are not always true.

Burroughs and Edwards.Am Heart J 1960;59:913-931

Darlings classification

The most common classification system was originally described by Darling et al. in 1957. consists of four types

Type I (Supracardiac TAPVC ): 45% of cases.

Both right and left pulmonary veins join a common pulmonary venous confluence behind the heart that drains via a vertical vein to the undersurface of the left innominate vein and thence to the Right atrium.

Type II ( Cardiac TAPVC) : 25% of cases.

The pulmonary venous confluence connects to the coronary sinus, & thence to the RA via the coronary sinus ostium.

Type III (Infracardiac TAPVC) : 21% of cases.

The pulmonary venous confluence drains inferiorly via a vertical vein to the portal vein or hepatic veins & thence to the RA.

Type IV (Mixed Type ) : <10% of cases.

Left pulmonary veins drain to the LIV , & right pulmonary veins to the coronary sinus

Darling RC et.al. Lab Invest.1957;6:44-64

THE FREQUENCIES OF THE VARIOUS SITES OF TAPVC OR

DRAINAGE

More than one-third of the cases had the anomalous connection to the left innominate vein (LIV).

ANATOMIC SITES OF OBSTRUCTION TO  PULMONARY VENOUS

DRAINAGE

The presence of an obstructive lesion in the anomalous pulmonary venous channel profoundly influences the  hemodynamic state and clinical features

Obstruction at the Interatrial Septum Burroughs and Edwards (40) clearly related longevity in

TAPVC to the size of the ASD. 

Those patients with large defects survived longer than did with restricted interatrial openings.

Obstruction in the Anomalous Venous Channel Intrinsic narrowing in the walls of the anomalous vessels or

Extrinsic pressure results in narrowing of venous structure .

For example, when the vertical vein in TAPVC to the innominate vein passes between the left main pulmonary artery and left main bronchus.

Similarly, the anomalous pulmonary vein in TAPVC  to the SVC may be obstructed by the right pulmonary artery & trachea.. 

Finally, when the anomalous connection is to the  portal vein or one of its tributaries, the hepatic sinusoids are interposed in the pulmonary venous channel and result in increased resistance to pulmonary venous return.  

ASSOCIATED CARDIAC ANOMALIES

TAPVC occurs as an isolated anomaly in two third cases.

It has been reported, however, to be associated with TGA , TOF, PDA, single ventricle , truncus arteriosus , tricuspid atresia , hypoplastic left heart syndrome ,pulmonary atresia, multiple small VSDs , COA , vascular sling, and other anomalies . 

Asplenia & polysplenia syndromes.

SK Choudhary, A Bhan, R Sharma, B Airan, V Devagourou, A Saxena,SS Kothari, Total-Anomalous-Pulmonary-Venous-Connection: Surgical Experience in Indians

Cardiothoracic Centre, All India Institute of Medical Sciences, New Delhi .Indian Heart J 2001; 53: 754–760)

PHYSIOLOGY All venous blood returns to the RA. 

Communication between the right and left sides of the heart - essential for survival . 

Physiologic features depend on the distribution of this mixed venous blood between the pulmonary and systemic circulations. 

The state of the interatrial septum is of primary importance in this distribution. 

During fetal life, PBF is small & the combined systemic and pulmonary venous return to the RA is only minimally increased.

Hence, the stimulus for the development of a large  interatrial communication is minimal.

Some degree of restriction to fow across a patent foramen ovale (found in 70% to 80% of cases) is common.

 In patients with a restrictive interatrial communication , the amount of blood reaching the LA is limited and systemic output is reduced.

 As pulmonary vascular resistance gradually decreases after birth and as demands for SBF increase with the rapid growth of the infant, massive pulmonary overcirculation ensues. 

Pulmonary and systemic venous blood return is to the RA , therefore, increased right atrial pressure results in pressure elevation and congestion in both venous circuits.

On the other hand, the presence of a widely patent  foramen ovale or ASD allows free communication between the two atria.

In this circumstance, the distribution of mixed  venous blood depends on the relative compliance of the atria and ventricles and the relative resistance  imposed by the pulmonary & systemic arterial circuits.

  The major variable is the state of the pulmonary

vascular bed , which initially depends on the presence or absence of pulmonary venous  obstruction.

TAPVC without Pulmonary Venous Obstruction

At birth, the distribution of blood between the  pulmonary & systemic circuits is approximately equal because the resistance in these two vascular beds is nearly equal. 

In the first few weeks of life , maturation of the pulmonary vascular bed produces a decrease in pulmonay vascular resistance , & a progressively larger proportion of the mixed venous blood traverses the pulmonary circuit. 

PBF is three to five times SBF. SBF is usually normal.

Progressive dilation and hypertrophy of RV and dilation of the pulmonary artery usually occur.

Pulmonary artery pressure in infants ranges from  slightly elevated to systemic. 

The state of the interatrial communication in  patients with TAPVC without pulmonary venous obstruction has a major impact on PBF , pressure and resistance. 

In the few patients who survive to older childhood or early adulthood , PA pressure is only slightly elevated. 

As time goes on, medial hypertrophy and 

intimal proliferation occur in the pulmonary arterioles, resulting in more severe pulmonary hypertension in the third and fourth decades.

TAPVC with Pulmonary Venous Obstruction

Elevated pressure in the pulmonary venous  channels is transmitted to the pulmonary capillary bed - pulmonary edema.

The right ventricular volume and pressure overload  result in a leftward shift of the interventricular septum that, together with the decreased inflow from the LA, lead to decrease in left ventricular volume. 

Systemic output usually is low because of the inadequate filling volume.

CLINICAL MANIFESTATIONS

The signs and symptoms in TAPVC are variable,  depending on the underlying hemodynamics. 

When the interatrial communication is inadequate , symptoms occur at birth or shortly thereafter.

The hemodynamic consequences of inadequate  interatrial communication include pulmonary  venous obstruction. 

The presence of intrinsic or extrinsic narrowing in  the connecting  vein also produces pulmonary  venous obstruction. 

Thus, the manifestations may be divided  according to whether pulmonary venous obstruction is absent or present.

CLINICAL FEATURES

TAPVC without Pulmonary Venous  Obstruction

Asymptomatic at birth. Tachypnea and feeding difficulties - within

first few weeks of life. Have recurrent resp.tract infections and

failure to thrive. Mild cyanosis Gradually they develop right heart failure

and pulmonary arterial hypertension

A prominent right ventricular heave .  A characteristic feature - multiple cardiac

sounds.  S1is Loud and often is often followed by a

systolic ejection click.  S2 widely split & does not vary with respiration,

The pulmonary component of the second sound is  accentuated. 

S3 maximal at apex almost always ,is present. S4 is frequently heard in older patients. Characteristically, a grade 2/6 soft , blowing ,

systolic ejection murmur is heard in pulmonary area .

When the anomalous connection is to the LIV, a venous hum at the left or right base may be heard. 

 Hepatomegaly & peripheral edema Clubbing occasionally is seen in the patient who 

survives infancy.

TAPVC with Pulmonary Venous Obstruction

Tachypnea, tachycardia and cyanosis within few hours of birth.

Dyspnea - pulmonary venous congestion and

cyanosis - reduced pulmonary flow.

If left untreated death may occur from pulmonary edema and RV failure within few days or weeks of life.

Once symptoms began- rapid progression to dyspnea , feeding difficulties and cardiorespiratory failure.

Age at death ranged from 2 days to 4.5 months .

When the anomalous connection is below the diaphragm , cyanosis & dyspnea may be accentuated by straining & swallowing as a consequence of interference of pulmonary venous outflow by increased intra-abdominal pressure or impingement of the esophagus on the CPV as it exits through the esophageal hiatus.

The clinical course in patients with severely obstructed infradiaphragmatic TAPVC might be stormy with rapid development of severe respiratory distress and acidosis in the first hours of life.

Despite the alarming symptoms, the cardiovascular findings may be minimal. 

No significant right ventricular heave.  S1 loud, S2 split, P2 loud   A cardiac murmur often is absent, but, when 

present, it is usually a soft blowing systoloic ejection murmur in the pulmonary area. 

Moist rales - lung bases.  Hepatomegaly and peripheral edema.

ELECTROCARDIOGRAPHIC FEATURES

TAPVC without Pulmonary Venous  Obstruction

A tall peaked P wave in lead II or the right  precordial leads characteristic of RA enlargement.

Right-axis deviation.

  Right ventricular hypertrophy –high voltage in the

right precordial leads

Occasionally as an incomplete RBBB pattern.

TAPVC with Pulmonary Venous  Obstruction

Right ventricular hypertrophy is invariably present.

  Unlike TAPVC without obstruction ,

however RA enlargement is not a usual feature.

CRITERIA OF RVH IN NEWBORNS Pure R wave 10 mm (with no S waves )in V1.˃ R wave in V1 25 mm or R wave in aVR 8 mm.˃ ˃ S wave in lead I 12 mm or greater. A qR pattern in V1.(also seen in10% of normal

newborns). Extreme RAD. Upright T waves in V1 after 1 week of age. Normally T wave upright until 4 to 7 days of

age. Between 1 week to adolescence it is negative and then reverts to upright.

RADIOLOGIC FEATURES

TAPVC without Pulmonary Venous  Obstruction

The RA and RV are enlarged, and the pulmonary artery segment is prominent. 

The left-sided chambers are not enlarged.

A figure-of-8 or snowman appearance of the cardiac shadow is seen in patients with TAPVC to the LIV . 

 “FIGURE OF EIGHT” OR “SNOWMAN'S” APPEARANCE.

Ground-glass appearance

Diffuse reticular pattern Cardiac size is normal Kerley B lines may be

present

TAPVC with Pulmonary Venous  Obstruction

ECHOCARDIOGRAPHIC FEATURES

Goals of the echocardiographic examination  

To establish the diagnosis;  To image and determine the size of the individual

pulmonary veins ;  To ascertain that all 4 pulmonary veins join the

pulmonary venous confluence and no additional pulmonary veins drain separately ; 

To image and determine the size of the pulmonary venous confluence and its relation to the LA; 

To image the course of the pulmonary venous  channel (usually the vertical vein ), its connection with systemic vein & its relation to neighboring structures (i.e., pulmonary arteries and airways); 

To determine whether there is obstruction to pulmonary venous flow ; 

To evaluate the interatrial communication for  obstruction; and 

To perform a complete anatomic and functional  survey of all cardiovascular structures & to exclude additional structural cardiac anomalies. 

These goals are achieved by performing a complete step by step echocardiographic examination from multiple windows.

The features common to all forms of TAPVC are

  Signs of Rright ventricular volume overload.  The right-sided heart structures are dilated.  The RA is enlarged, and the atrial septum

bows toward the left.  The right ventricle appears to compress

the left ventricle, the interventricular septum  deviates leftward,and left ventricular volume is  decreased. 

The IVS septum may move paradoxically.  The pulmonary arteries are dilated.

Features of right ventricular volume overload, the  first echocardiographic suspicion that supports the diagnosis of TAPVC is the inability to image the pulmonary veins entering the LA & LA is small. 

The pulmonary venous confluence - echo free space behind the LA.

The individual pulmonary veins - parasternal , subclavicular & suprasternal notch views mostly used.

Once the pulmonary venous confluence is characterized, the venous channel that connects with the systemic vein is followed by 2-D imaging and color Doppler flow mapping. 

The venous channel in  Supracardiac TAPVC - precordial windows Infradaiphragmatic TAPVC - subcostal view.

 In supracardiac TAPVC, the venous channel should be examined for its relation with the branch pulmonary arteries and the bronchi.

In TAPVC to coronary sinus, the sinus is dilated and bulges anterosuperiorly into the LA.

Imaging of the pulmonary veins draining into the coronary sinus is important for diagnosis because CS may be dilated in other conditions also like persistent LSVC to CS.

Descending anomalous vein is characterized by the venous flow pattern and direction of flow is away from the heart towards abdomen.

An increased flow velocity, turbulent flow pattern and loss of phasic variations characterize obstructed pulmonary venous flow. (normal venous flow is low velocity, phasic laminar pattern with brief flow reversal during atrial systole)

MRI AND CT IMAGING

CARDIAC CATHETERIZATIONTAPVC without Pulmonary Venous  Obstruction

The venous site of anomalous connection may be  identified if highly saturated blood is obtained from LIV, right SVC, or CS. 

In TAPVC, the oxygen saturation in the RA- usually ranges between 80% and 95%, and saturations in  the RA, RV, PA, LA, LV and systemic arteries are nearly identical.

Pressure in RV & PA ranges from slightly elevated to equal or higher than systemic pressure.

  Interpretation of atrial pressures – adequacy of

the interatrial communication, is difficult.

  The presence of equal pressures in the two atria -

nonobstructive intera-trial communication. 

A RA pressure >2 mm Hg in excess of LA pressure - restrictive interatrial communication.

TAPVC with Pulmonary Venous  Obstruction

Difficult in patients with obstructed TAPVC

Must be avoided – May aggravate already compromised clinical condition of these patients and delay operation.

Right ventricular pressures usually are systemic or higher.

Pressures in the RA usually are normal.

LA pressure is normal.

Selective pulmonary arteriography - in levophase shows the anomalous venous connections.

THE TREE IN WINTER – INFRACARDIAC TYPE

NATURAL HISTORY

Among patients of TAPVC of all types, 50% die at 3 months and almost 80% die by the age of 1 year

Asymptomatic at birth

56% symptomatic at 1st month of life

Failure at 6 months of age

Severe obstruction pulmonary edema 1st few hrs

Cyanosis mild, more with failure & pulm vascular changes

Death – 1st few wks/months of life in most neonates

80% death – 1st year of life

Survivors of 1st few wks of life – ↑pulm bld flow mild cyanosis, PHTN

50% survive beyond 3 months

Median survival 3wks (obst) & 2.5 months in (non obstr)

Infracardiac- worse prognosis- 3wks survival

MANAGEMENT Corrective surgery - definitive treatment.

Infants presenting with obstructed TAPVC represent surgical emergency. They need require intensive resuscitation before going for definitive surgery.

Nonobstructed TAPVC patient are relatively stable and can be taken for elective corrective surgery within few days of diagnosis irrespective of patients age and weight.

EMERGENCY MEDICAL MANAGEMENT

Mechanical ventilation.

Correction of Metabolic acidosis.

Inotropic support

Prostaglandin therapy (PGE1)

ADDITIONAL INTERVENTIONS INCLUDE

Extracorporeal membrane oxygenation (ECMO) may be used in infants with severe pulmonary hypertension or refractory cardiac failure.

Balloon or blade atrial septostomy may be used as a palliative procedure.

It is not appropriate because it delays the definitive procedure and is of no value in obstructed venous channel.

SURGERY

The goal of the surgery is

To create a communication between LA and the pulmonary venous.

Closure of the anomalous pulmonary venous connections to systemic circulation

Closure of ASD

The surgical approach is via a median sternotomy and is performed under cardiopulmonary bypass with circulatory arrest. The surgical procedure varies depending upon the anatomy of the TAPVC lesion.

In supra- and infracardiac TAPVC with a common vertical vein, a normal pulmonary venous pathway is created by opening and forming an anastomosis between the pulmonary venous confluence and the left atrium. The vertical vein is then ligated and divided.

SUPRACARDIAC TAPVC:

INFRACARDIAC TAPVC:

CARDIAC TAPVC: In intracardiac TAPVC to the coronary sinus, the

sinus and the partition between the sinus and right atrium are incised, and connected to the left atrium.

MIXED TYPE TAPVC

The repair of mixed type TAPVC involves a combination of the above approaches as dictated by the specific anatomy of the lesion

Recurrent pulmonary venous obstruction

SURGICAL OUTCOMES

Surgical mortality has decreased from approx. 50% in 1960 to 5% recently.˂

 Risk factors for mortality included earlier age at surgery, hypoplastic/stenotic pulmonary veins, associated cardiac lesions, postoperative pulmonary hypertension, postoperative PVO , Small pulmonary vein and confluence size & Increased total bypass and circulatory arrest time .

SURGICAL OUTCOMES RISK FACTORS

377 patients of operated TAPVC were followed retrospectively.pulmonary venous obstruction was in 48% of

patients.

SURGICAL OUTCOMES IN NEONATES

112 patient were followed retrospectively who were operated for simple TAPVC in first month of life from 1973 to 2008.

Preoperative pulmonary venous obstruction in 89 pts (80%).

There were 12 (10.7%) early deaths. Significant risk factors were bypass time 65 minutes and emergent ˃surgery.

Survival at 20 years was 83.4%.Risk factors for late death were operative weight 2.5 kg or less and postoperative pulmonary hypertensive crisis.

Re-operation for recurrent PVO was in 13 patients (11.9%).

SURGICAL OUTCOMES IN INDIA

73 pts, were operated on for TAPVC from Jan 1987 to Oct 1997.

35 patients had obstructed drainage. Operative mortality was 23.3% (17 out of 73).

COMPLICATIONS OF SURGERY

EARLY- Pulmonary edema Pulmonary hypertensive crisis Phrenic nerve damage Rhythm disorders

LATE- Pulmonary venous obstruction Anastomotic stricture Pulmonary venous stenosis

Pulmonary edema- noncompliant left heart and increased left atrial pressure leads to pulmonary arteriolar vasoconstriction. Diuretics are useful for treatment.

Pulmonary hypertensive crisis-hyperventilation with 100% oxygen and inhaled nitric oxide is the treatment of choice. Infusion of prostacyclin may also be useful.

Rhythm disorders- junctional rhythms and various types of heart blocks are common in cardiac type TAPVC repair.

Pulmonary venous obstruction

This is most significant cause of late morbidity and mortality after corrective surgery.

It develops in 5-15% of patients within first postoperative year where TAPVC is corrected using standard technique.

Anastomotic fibrotic strictures, intimal proliferation and diffuse fibrosis are pathogenic mechanisms.

REOPERATION

 Based upon a number of case series, the rate for reoperation is between 10 and 15 percent in patients with isolated TAPVC (11 percent) .

Stenosis of individual pulmonary vein and surgical anastomosis are the primary reasons for reoperation.

If restenosis does not occur within one year after surgical repair, then reoperation is rarely required.

MORBIDITY

Although long-term follow-up data are limited, one case series reported a poorer perception of health and school performance in survivors of TAPVC correction.

In addition, several case series noted an increased risk of arrhythmias, especially sinus node dysfunction .

This may be due to disruption of the conduction system by the atrial incision used to repair TAPVC.

Children with TAPVC should undergo appropriate surveillance, screening, and or referral for neurodevelopmental impairment as recommended in a 2012 scientific statement from the American Heart Association.

follow-up care should be individually planned through the primary caregiver in collaboration with a pediatric cardiologist

In the absence of residual pulmonary vein stenosis or pulmonary hypertension, exercise tolerance is generally normal in children with repaired TAPVC regardless of the anatomic subtype.

Physical activities and sports participation should not be

restricted. Infective endocarditis prophylaxis precautions should be considered within the first six months after surgical repair, after which it is no longer required.

FOLLOW-UP CARE

Periodic screening for arrhythmias is not routinely recommended in asymptomatic children with repaired TAPVC.

Because of the known association between intracardiac surgical repairs and atrial arrhythmias, however, periodic Holter monitoring may be considered in asymptomatic adolescents

CONCLUSION

TAPVC is a rare congenital heart anomaly but presents as a surgical emergency in neonatal periods.

Echocardiography is the diagnostic modality of choice.

Cardiac catheterization is rarely needed for diagnosis.

Surgical correction is the definitive treatment.

Improved surgical techniques and hospital care have led to significantly better outcomes of TAPVC surgery.

Suturless repair is safe and effective method to deal with post operative pulmonary venous obstruction.

DIFFERENTIAL DIAGNOSIS

Non obstructive TAPVC - Conditions producing high pulmonary flow

with cyanosis like TGA ,Taussig Bing anomaly, persistent truncus arteriosus and common atrium.

Obstructive type of TAPVC- Conditions producing PAH without shunt

lesion like congenital mitral stenosis, cor-triatriatum, pulmonary venous stenosis and persistent fetal circulation.

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