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Eisenmenger's syndrome

icanis
Contributor(s):

Serena Brownlie

Synonym(s): Eisenmenger's physiology


Introduction

  • Eisenmenger's syndrome is NOT a primary heart disease but a description of a secondary response to the primary cardiac anomaly, typically VSD or PDA.
  • See also Eisenmenger's complex Eisenmenger's complex.
  • Describes changes that occur when a left to right shunting cardiac defect, eg VSD, PDA, causes pulmonary overperfusion, leading to pulmonary hypertension and eventually reversed shunting (right to left) as the right heart pressures increase and become equal to or greater than systemic arterial pressures.
  • Deoxygenated blood is pumped into systemic circulation → cyanosis, hypoxia stimulates erythropoietin release → polycythemia.
  • Signs: include dyspnea, exercise intolerance, collapse, seizures, stunted growth, cyanosis, polycythemia and heart murmurs.
  • Treatment: palliative.
  • Prognosis: typically very poor.

Pathogenesis

Predisposing factors

General
  • Breed.
  • Sex.

Specific

Pathophysiology

  • PDA - failure of muscular ductus arteriosus to close after birth resulting in aorta-to-pulmonary artery communication.
  • VSD - failure of interventricular septum leaving communication between left and right ventricles.
  • Large atrial septal defect Atrial septal defect in association with pulmonic stenosis Pulmonic stenosis.
  • Left-to-right shunt from aorta to pulmonary artery (PDA) or left-to-right shunt across interventricular septal defect (VSD) → increased blood flow through pulmonary vasculature.
  • Increased pulmonary arterial and arteriolar pressure stimulates progressive myointimal proliferation, endothelial degeneration, intimal fibrosis and hyalinzation → occlusion of pulmonary vessels ("pruning").
  • Increasing right ventricular pressure as pulmonary hypertension Pulmonary Arterial Hypertension (PHT) develops → right ventricular pressure eventually becomes equal to and then exceeds left ventricular/systemic pressure → right-to-left shunting.
  • Deoxygenated blood is pumped into systemic circulation → cyanosis → hypoxia → stimulate erythropoietin release in kidneys → increased red blood cell production → polycythemia.

Timecourse

  • PDA - reversed shunting if it is going to occur usually happens before 6 months of age.
  • VSD - development of reversed shunting (Eisenmenger's physiology) is dependent on the size of interventricular defect.
  • Significant risk exists when pulmonary flow:systemic flow ratio exceeds 2:1.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Lieb A et al (1998) Case report - Eisenmenger syndrome in a 9-month-old border collie puppy. Schweiz Arch Tierheilkd 140 (4), 164-167 PubMed.
  • Ware W A, Bonagura J D (1988) Multiple congenital cardiac anomalies and Eisenmenger's syndrome in a dog. Comp Cont Ed 10 (8), 932-949 VetMedResource.
  • Feldman E C, Nimmo-Wilkie J S, Pharr J W (1981) Eisenmenger's syndrome in the dog: case reports. JAAHA 17 (3), 477-483 VetMedResource.
  • Nimmo-Wilkie J S, Feldman E C (1981) Pulmonary vascular lesions associated with congenital heart defects in three dogs. JAAHA 17 (3), 485-490 VetMedResource.

Other sources of information

  • Ettinger S J & Feldman E C (1995).Congenital heart disease.In:Textbook of Veterinary Internal Medicine. 4th edn. pp 892-943.
  • Noden D M & DeLahunta A (1985)The Embryology of Domestic Animals - Developmental Mechanisms and Malformations.

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