Congenital heart disease
How heart defects follow from a septum, shunt or outflow division that failed in development, why pressures after birth decide which way blood crosses, and how shunts, cyanotic lesions and obstructions cause their signs.
By the end, you can
- Relate each common defect to the step of heart development or the fetal shunt that failed.
- Explain how the fall in pulmonary resistance at birth sets the direction and timing of shunts.
- Explain how a large left-to-right shunt causes heart failure and can progress to Eisenmenger syndrome.
- Explain the cyanosis of tetralogy of Fallot and transposition, and the effects of coarctation and valve stenosis.
- Recognise the classic signs, classifications and tests of congenital heart disease, and explain how each main treatment acts on the mechanism.
What it is
Congenital heart disease is a structural abnormality of the heart or great vessels present at birth, arising when a step of heart development fails or a fetal shunt does not close. Defects are grouped by their effect: left-to-right shunts and obstructive lesions, which do not cause cyanosis at first, and right-to-left lesions, which do.
4 types to tell apart
- Left-to-right shunts
- Atrial and ventricular septal defects, patent ductus arteriosus and atrioventricular septal defect: oxygenated blood recirculates through the lungs, a volume load.
- Right-to-left (cyanotic) lesions
- Tetralogy of Fallot and transposition of the great arteries, among others: oxygen-poor blood reaches the body without passing through the lungs.
- Obstructive lesions
- Coarctation of the aorta and aortic and pulmonary stenosis: a narrowing loads the ventricle behind it with pressure.
- Eisenmenger syndrome
- The late reversal of a large left-to-right shunt once the pulmonary arteries have remodelled, turning an acyanotic defect into a cyanotic one.
US spelling: centre → center.
Normal function
How one tube becomes four chambers and two arteries
Between about weeks 4 and 8 the looped heart tube is divided from inside while it keeps beating. In the atria a thin grows down towards swellings in the canal between atria and ventricles. The gap below its edge, the , closes as it meets them, but holes open in its upper part (the ). A thicker then grows down on its right and stops short, leaving the foramen ovale, with the septum primum as a one-way flap.
The swellings, the , fuse to divide the canal into the tricuspid and mitral openings and to build the centre of the heart. Below, a rises from the floor of the ventricles; the last gap above it is closed by the thin , made from the cushions and the ridges of the outflow tract.
The single outflow tract is divided by ridges that fuse into a twisting aorticopulmonary septum, so the leaves the right ventricle and the the left, wound round each other. Before birth the carries most of the right ventricle’s output into the aorta past the fluid-filled lungs. Each defect in this lesson is one of these steps left incomplete or done wrongly.
Underlying change · Step 1 of 6
At birth: the fetal shunts close and pressure sets the direction
The full lesson is part of Student Pro
It takes you through all 6 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Disrupted function · Step 2 of 6
Left-to-right shunts: septal defects, PDA and AVSD
The full lesson is part of Student Pro
It takes you through all 6 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Consequences · Step 3 of 6
Too much flow to the lungs: heart failure and Eisenmenger syndrome
The full lesson is part of Student Pro
It takes you through all 6 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Disrupted function · Step 4 of 6
Tetralogy of Fallot: one misaligned septum, four features
The full lesson is part of Student Pro
It takes you through all 6 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Disrupted function · Step 5 of 6
Transposition of the great arteries: two circulations side by side
The full lesson is part of Student Pro
It takes you through all 6 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Disrupted function · Step 6 of 6
Obstructive lesions: coarctation, aortic and pulmonary stenosis
The full lesson is part of Student Pro
It takes you through all 6 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Symptoms and signs
Symptoms, signs and findings
The full lesson is part of Student Pro
It takes you through all 6 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Exam detail
Exam detail
The full lesson is part of Student Pro
It takes you through all 6 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Treatment
How treatment works
The full lesson is part of Student Pro
It takes you through all 6 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Recap
Recap
The full lesson is part of Student Pro
It takes you through all 6 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Self-check
Check your understanding
The full lesson is part of Student Pro
It takes you through all 6 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .