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PA26.{4,9} | Congenital Heart Disease & Cardiomyopathies — SDL Guide (Part 3)

Obstructive Lesions — Coarctation of Aorta

Diagram showing juxtaductal coarctation of the aorta, contrasting preductal and postductal types with their pressure, pulse, and collateral consequences. — **Panel A:** Heart, ascending aorta, aortic arch, brachiocephalic trunk, left common carotid artery, left subclavian artery, juxtaductal coarctation, ductus arteriosus/ligamentum arteriosum, descending thoracic aorta, high proximal pressure, reduced distal flow.. **Panel B:** Preductal infantile coarctation proximal to a widely patent ductus arteriosus; postductal adult coarctation distal to a closed ductus/ligamentum arteriosum; pulmonary artery, descending aorta, lower body perfusion pathway.. **Panel C:** Upper limb hypertension, diminished femoral pulses, radiofemoral delay, intercostal collateral arteries, rib notching, reduced lower limb perfusion..

Coarctation of aorta is a discrete narrowing of the aortic lumen, classically near the ductus arteriosus (juxtaductal). Two types based on position relative to the ductus:

Feature	Preductal (Infantile)	Postductal (Adult)
Position	Proximal to ductus	Distal to ductus
Ductus	Widely patent (required for lower body perfusion)	Closed/ligamentum
Presentation	Neonatal heart failure	Hypertension in young adult
Lower limb pulses	Diminished/absent	Diminished; radiofemoral delay
Collaterals	Not developed	Well-developed intercostal collaterals

Associations: Turner syndrome (45,X) — bicuspid aortic valve + coarctation is the classic pairing.

Gross: Ridge/shelf of intimal and medial tissue narrowing the lumen. Dilated proximal aorta. Collateral channels — internal mammary, intercostal arteries enlarge → rib notching on CXR (3–9th ribs bilaterally).

Complications: Hypertension (upper body), LV hypertrophy, aortic dissection/rupture, IE, intracranial haemorrhage (Circle of Willis aneurysms from hypertension).

Haemodynamic 'E' sign / '3' sign on CXR: indentation of the aorta between the proximal dilation and post-stenotic dilation.

SELF-CHECK

A 19-year-old woman with Turner syndrome (45,X) is found to have blood pressure 160/90 mmHg in both arms but weak and delayed femoral pulses bilaterally. Chest X-ray shows rib notching (ribs 3–9). What is the most likely cardiac finding?

A. Postductal coarctation of aorta with intercostal collateral vessels

B. Preductal coarctation of aorta with patent ductus arteriosus

C. Bicuspid aortic valve with aortic regurgitation

D. Atrial septal defect with pulmonary hypertension

Reveal Answer

Answer: A. Postductal coarctation of aorta with intercostal collateral vessels

The combination of hypertension in the upper extremities with radiofemoral delay, rib notching (due to enlarged intercostal collateral arteries), and Turner syndrome (45,X) is the classic presentation of postductal (adult-type) coarctation of the aorta. The ductus is closed (ligamentum arteriosum), so intercostal collaterals have had years to develop, eroding the inferior rib margins. Turner syndrome also commonly includes a bicuspid aortic valve.

Cardiomyopathies — Classification and Overview

A classification diagram compares dilated, hypertrophic, restrictive, and arrhythmogenic right ventricular cardiomyopathies by chamber shape, myocardial change, and dominant functional defect. — **Panel A:** Classification overview showing primary myocardial disease, exclusion of ischaemia, hypertension, valvular disease and congenital anomalies, and branches to DCM, HCM/HOCM, RCM, and ARVC.. **Panel B:** Dilated cardiomyopathy showing four-chamber dilatation, thin stretched ventricular walls, increased wall stress, systolic failure, and markedly reduced EF.. **Panel C:** Hypertrophic cardiomyopathy showing asymmetric septal hypertrophy, small stiff LV cavity, possible LVOT obstruction, diastolic failure, and normal or increased EF.. **Panel D:** Restrictive cardiomyopathy showing normal or reduced ventricular cavity size, stiff ventricular walls, impaired diastolic filling, preserved EF, and possible secondary systemic causes.. **Panel E:** Arrhythmogenic right ventricular cardiomyopathy showing RV free-wall fibro-fatty replacement, RV dilatation, and ventricular arrhythmia risk..

Cardiomyopathies are primary diseases of the myocardium not caused by ischaemia, hypertension, valvular disease, or congenital anomalies (though secondary cardiomyopathies from systemic disease are included in the restrictive group).

The WHO/ESC classification recognises three main functional types:

Type	Dominant Defect	Chamber Change	Function
Dilated (DCM)	Systolic failure	4-chamber dilatation + ↑ wall stress	EF markedly reduced
Hypertrophic (HCM/HOCM)	Diastolic failure ± LVOT obstruction	Asymmetric septal hypertrophy	EF normal or ↑; stiff, non-compliant LV
Restrictive (RCM)	Diastolic failure	Normal/↓ cavity; stiff walls	EF normal; impaired filling

A fourth category, arrhythmogenic right ventricular cardiomyopathy (ARVC), involves fibrofatty replacement of the RV myocardium.

Three side-by-side gross heart sections compare dilated, hypertrophic, and restrictive cardiomyopathy with labeled chamber size, wall thickness, septal hypertrophy, thrombus, and amyloid changes. — **Panel A:** Dilated cardiomyopathy showing four-chamber dilatation, thin flabby ventricular walls, dilated LV and RV cavities, pale endocardium, and mural thrombus at the LV apex.. **Panel B:** Hypertrophic cardiomyopathy showing asymmetric septal hypertrophy, narrowed LV outflow tract, thickened LV free wall, small LV cavity, and banana-shaped LV cavity.. **Panel C:** Restrictive cardiomyopathy showing near-normal chamber size, stiff non-dilated ventricles, granular waxy endocardium, amyloid deposition, and mild biatrial enlargement..

Dilated Cardiomyopathy — Pathology and Causes

A three-panel educational diagram showing gross dilated cardiomyopathy, its major causes, microscopic pathology, and clinical complications. — **Panel A:** Normal heart, dilated cardiomyopathy heart, four-chamber dilatation, thin pallid endocardium, LV dilatation, RV dilatation, LV apical mural thrombus, atrial appendage thrombus, mitral annular dilatation, mitral regurgitation.. **Panel B:** Idiopathic, genetic mutations, TTN, lamin A/C, desmin, alcohol toxicity, peripartum cardiomyopathy, viral myocarditis, Coxsackievirus B3, parvovirus B19, CMV, doxorubicin toxicity, Chagas disease, Trypanosoma cruzi, thiamine deficiency, selenium deficiency.. **Panel C:** Hypertrophied myocytes, interstitial fibrosis, scattered myocyte loss, absent active inflammation, no myofibre disarray, systolic heart failure, thromboembolism, sudden cardiac death, arrhythmia, mitral regurgitation..

Dilated cardiomyopathy (DCM) is the commonest cardiomyopathy and the leading cause of cardiac transplantation.

Causes:
• Idiopathic (~50%) — many have underlying genetic mutations (titin, lamin A/C, desmin — cytoskeletal proteins)
• Genetic (~25%) — familial DCM; autosomal dominant; titin (TTN) mutations most common
• Alcohol — toxic myopathy; reversible in early stages
• Peripartum cardiomyopathy — onset last month of pregnancy or first 5 months postpartum; immune/prolactin-mediated
• Viral myocarditis → post-inflammatory DCM (Coxsackievirus B3, parvovirus B19, CMV)
• Doxorubicin (Adriamycin) — cumulative dose-dependent free-radical toxicity to mitochondria; irreversible above 550 mg/m²
• Chagas disease — Trypanosoma cruzi; important in South America
• Nutritional — thiamine deficiency (beriberi), selenium deficiency (Keshan disease)

Gross: Flabby, dilated all four chambers (biventricular > right-dominant). Endocardium pallid, thin. Mural thrombi common in LV apex and atrial appendages.

Micro: Myocyte hypertrophy (compensatory), interstitial fibrosis, scattered myocyte loss. Inflammation absent (distinguishes from active myocarditis). No myofibre disarray.

Complications: Heart failure (systolic), thromboembolism, sudden cardiac death (arrhythmia), mitral regurgitation (annular dilatation).