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TRICUSPID ATRESIA

overview

Tricuspid atresia is the third most common cyanotic congenital heart disease in which the non oxygenate blood can not flow from right artrium to right ventricle due to non development or agenesia of tricuspid valve. Right ventricle is small and pulmonary artery in some cases is stenotic.

Majority of infants with die in the first year of life without surgery. ASD or PFO are necessary for passing the blood from right atrium to left system and with out them the infants will not survive.


Historical perspective

Tricuspid atresia was first discovered by friedrich ludwig kreysig in 1817, a German physician who found the obstruction between right atrium and right ventricle . The classic term of tricuspid atresia was used firstly by schuberg in 1861.

Pathophysiology

Inferior vena cava and superior vena cava collect venous non oxygenate blood into right atrium. Through ASD blood reach to left atrium and finally flow into left ventricle and via aorta artery goes into the rest of body. This blood is the mixture of saturated and unsaturated O2. If there is VSD, this mixed blood in left ventricle come into right ventricle via VSD , then via pulmonary artery flows into pulmonary bed and becomes oxygenate ,then returns back into left atrium . In deminished pulmonary blood flow whether the flow is dependent on PDA, the mixed blood in aora flow from this passage into pulmonary artery and pulmonary bed.

In the presence of normal positioning of great arteries cyanosis is more prominent and is affected by the size of VSD .TGA and subaortic stenosis and persistent left superior vena cava are others associated anomalies

Classification

Tricuspid atresia is classified according to connection between ventricles with great arteries(aorta, pulmonary) into two subgroups:

  • ·        Normal connection between ventricles and  aorta and pulmonary artery . this type is much more common and consistence 70%-80% of cases.Most patients are cyanotic.
  • ·        Aorta comes from small  right ventricle and pulmonary artery comes from left ventricle. Heart failure and pulmonary hypertension are common . Systemic Flow in aorta is dependent on VSD size . Subaortic stenosis and aortic arch anomalies are common




Differentiating tricuspid atresia from other Diseases

  • Tricuspid atresia must be differentiated from other diseases that cause lung olygemia and cyanosis , such as
  • TS
  • PS
  • ASD
  • TOF



Epidemiology and Demographics[edit | edit source]

  • The prevalence of tricuspid atresia is approximately 1.2 per 100,00 live births.

Age

  • Tricuspid atresia is more commonly observed among infant less than one year old.

Gender

  • Tricuspid atresia affects male and female equally.

Race

  • There is no racial predilection for tricuspid atresia



Risk Factors[edit | edit source]

  • There is no specific risk factors for occurance of tricuspid atresia during pregnancy .
  • few cases of VACTERL association and chromosomal abnormalities including triosomy 13,18 and tetrasomy 22 were reported.

Natural History, Complications and Prognosis[edit | edit source]

  • Early clinical features in infants include cyanosis of lips and tongue, difficulty in breathing, tiring easily during feeding
  • severity of cyanosis in infants with pulmonary stenosis is dependent on the amount of pulmonary blood flow passing through patent dactus arteriosis .After physiologic clousure of PDA , the cyanosis will be aggravate.
  • in patients with normal pulmonary blood flow, complications of heart failure is common.
  • Prognosis is generally poor with out surgery and majority of patients will die before 1 year old. The 15 year survival of patients with fontan procedure is approximately %92 according to Merry et al.

Diagnosis[edit | edit source]

Diagnostic Criteria[edit | edit source]

  • The diagnosis of tricuspid atresia is made when at least of the following three diagnostic criteria are met in echocardiography:

Absent of color flow doppler in tricuspid valve region

ASD or PFO

Small right ventricle

Left atrium dilation

Left ventricle dilation




Symptoms[edit | edit source]

  • Symptoms of tricuspid atresia in neonates may include the following:
  • Central cyanosis in mucous membranes and tongue
  • Poor feeding and growth retardation
  • Difficulty in breathing
  • Rapid heart beat
  • Rapid breathing

Physical Examination

  • Patients with pulmonary stenosis and closed PAD usually appear cyanotic after birth.
  • Physical examination may be remarkable for:
  • Normal pulses
  • Deminished right ventricle impulse
  • Thrill due to VSD or severe PS
  • Holosystolic murmure in LSB due to VSD
  • Continuous murmur of PDA ,occasionally
  • Systolic ejection murmur in left upper sternal border due to PS
  • clubbing in older patients and unrepaired disease.
Patients with high pulmonary blood flow without stenosis in pulmonary artery and with VSD are not cyanotic at birth.
Physical examination may be remarkable for symptoms and signs of overt heart failure:
  • Tachypnea
  • poor feeding
  • poor growth

Laboratory Findings[edit | edit source]

  • There are no specific laboratory findings associated with tricuspid atresia
  • polycytemia may be found in cyanotic patients.

Imaging Findings[edit | edit source]

  • Echocardiography is the imaging modality of choice for tricuspid atresia.Findings include ;ASD, VSD, PDA, and aortic arch anomaly, left ventricle is larger than right ventricle and color flow doppler is absent between right atrium and right ventricle.
  • On EKG, tricuspid atresia is characterized by left axis deviation, left ventricle hypertrophy, right atrium enlargment and left atrium enlargment in increment amount of of pulmonary blood flow.
  • CXR may demonestrate situs solitus, left sided aortic arch ,levocardia, absent main pulmonary artery, heart size is dependent on pulmonary blood flow, occasionally pulmonary oligemia with decrease vascular markings, right aortic arch in %25 of cases.
  • Catheterization may measure the gradient between left ventricle and left atrium in subaortic stenosis.

Treatment[edit | edit source]

Medical Therapy[edit | edit source]

  • The mainstay of therapy for cyanotic neonate with severe PS and small VSD is using prostaglandin E1 (PGE1) for keeping patency of ductus arteriosis.
  • The mainstay of therapy for heart failure symptoms is using diuretic for reloading and then starting ACEI.

Surgery[edit | edit source]

  • Surgery is the mainstay of therapy for tricuspid atresia.
  • ·        In first 8 weeks of life if there is  severe cyanosis and pulmonary obstruction and  normal positioning aorta and pulmonary artery , making a shunt between systemic subclavian artery to pulmonary artery is necessary which is called Blalock -taussig(BT shunt).
  • ·        If pulmonary artery comes from left ventricle and is overflowed, PA banding is useful for lowering the pulmonary blood flow.
  • ·        In older children, bidirection Glenn shunt which is the connection between superior vena cava to pulmonary artery will done for transferring the blood to pulmonary system.
  • Fontan procedure is a coduit between inferior vena cava and pulmonary artery and transfers the systemic venous blood to pulmonary circulation in age of 2-3 year old.
  • Endocarditis prophylaxi before every procedures is recommended.

Prevention

  • Effective measures for the primary prevention of tricuspid atresia include fetal echocardiography and sonography in 20th weeks of pregnancy for prenatal screening.
  • Once diagnosed and surgically treated ,post operated patients with fontan palliative shunt should be evaluated by cardiac MRI. follow up may be about the complications of fontal shunt including:

exercise intolerance as the result of ventricular failure,

pericardial and pleural effusion,chylothorax, protein losing enteropathy due to lymphatic dysfunction

pulmonary emboli,blood clot formation in shunt,

liver failure and portal hypertention as a result of increased pressure in shunt.

leakage of anastomosis and pulmonary hypertention.

right atrium dilation and arrhythmia

References

1..{cite book | last = Zipes | first = Douglas | title = Braunwald's heart disease : a textbook of cardiovascular medicine | publisher = Elsevier/Saunders | location = Philadelphia, PA | year = 2019 | isbn = 978-0323462990 }}

2.Minocha PK, Phoon C. Tricuspid Atresia. [Updated 2020 Jan 24]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK554495/

3.Fredenburg TB, Johnson TR, Cohen MD. The Fontan procedure: anatomy, complications, and manifestations of failure. Radiographics. 2011;31(2):453-463. doi:10.1148/rg.312105027


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