The boot shaped heart sign

The Boot-shaped Heart Sign

Thorsang Chayovan

Outline

• Overview of the

boot-shaped heart sign

• Tetralogy of Fallot

– Overview

– Radiology

– Prognosis and Treatment

Haider, Ehsan A. "The Boot-shaped Heart Sign." Radiology.rsna.org. RSNA, 1 Jan. 2008. Web. 23 July 2012. <http://radiology.rsna.org/content/246/1/328.full>.

The Boot-shaped Heart Sign

• Frontal chest radiograph

• The shape of a wooden boot

• Tetralogy of Fallot




Tetralogy of Fallot

• One of the most common cyanotic congenital heart conditions (75%)

• Accounts for 10% of all congenital heart diseases

• Has estimated prevalence of 1 in 2,000 birth

Congenital Heart Diseases


Acyanotic Cyanotic


Acyanotic

• Simple and single lesion

• Mechanism

– Left-to-right shunt

– Obstructive lesion

Cyanotic

• Multiple and probable complex lesions

• Capillary reduced hemoglobin > 5 gm%

(Oxygen saturation < 85%)

• Mechanism

– Right-to-left shunt

– Common mixing

– Parallel circulations

Tetralogy of Fallot

• Eccentric septation of the truncus arteriosus• Conotruncal septum is displaced anteriorly

– The infundibular septum fails to fuse with the top of the interventricular septum high VSD

– The anterior part of aortic valve (superior border of the VSD) overrides the ventricular septum overiding aorta

– The right ventricular outflow tract obstruction or Pulmonary stenosis

– Right ventricular hypertrophy—right ventricle at systemic pressure—later in life

Embryogenesis of the heart

Witmer, Lawrence M. "Developmental Anatomy of the Heart and the Embryological Basis for Cardiac Defects." Ohio University, Athens. 23 July 2012. Lecture.

Tetralogy of Fallot

• Obstruction of the right ventricular outflow tract

• High VSD

• Overriding aorta

• Right ventricle hypertrophy

+ Atrial septal defect Pentalogy of Fallot

Cukukoglu, Sardar M. "Cyanotic Diseases." Escardio.org. N.p., 2010. Web. 23 July 2012.

<http://www.escardio.org/congresses/euroecho2010/Documents/teaching-course-slides/euroecho2010-cyaotic-disease-Kucukoglu-591.pdf>.

Tetralogy of Fallot

• Cyanosis

– Severe cases ↔ at birth ↔ severe PS

– Mild cases ↔ much later ↔ mild PS

• Squatting

• Dyspnea

• Failure to thrive

Tetralogy of Fallot

• Degree of pulmonary stenosis determines the clinical picture

– If mild, the clinical picture of VSD is shown instead

– However the muscular element of pulmonary stenosis is nearly always progressive

– Eventually reversing the left to right shunt to be permanently right to left before the first birthday

Radiology in Tetralogy of Fallot

• The Boot-shaped Heart sign

“coeur en sabot”– The UPPER part of the

Boot: flat / concave pulmonary trunk

– The TOE--upward pointing cardiac apex: concentric right ventricular hypertrophy

Accentuated by large lung volume, small thymus, and lordoticprojection

Radiology in Tetralogy of Fallot• Heart size

– The heart is usually not enlarged at birthUnless there is a large left-to-right shunt

– Could be enlarged in later life from biventricular hypoxic failure

• Pulmonary vasculature—decreased

• Aortic arch– Always enlarged

– 25% has right-sided aortic arch• might be associated with absent left pulmonary artery• resulting in less pulmonary vasculature in the left lung

Upturned cardiac apex sign

• Concentric right ventricular hypertrophy

• However not seen in severe pulmonic stenosis with intact interventricular septum

(RV systolic pressure >>> systemic systolic pressure)

• Maybe related to right ventricular hypertrophy with altered development of the left ventricle and abnormal horizontal ventricular septum

• Only encountered in congenital heart lesions and not in acquired right ventricular hypertrophy

Gallard, Frank. "Tetralogy of Fallot." Radiopaedia.org. N.p., 5 Jan. 2010. Web. 23 July 2012. <http://radiopaedia.org/images/156636>.

"Cyanotic Heart Diseases." Learningradiology.com. N.p., n.d. Web. 23 July 2012. <www.learningradiology.com/.../cyanoticheartdz.pdf>.

MRI

• Exquisite anatomical and functional information • Detailed assessment of the pulmonary artery is

particularly important– Repair of the cardiac defects without addressing

pulmonary artery hypoplasia / stenosis has a poor outcome

• The main pulmonary artery or right pulmonary artery/ascending aorta < 0.3– Primary repair would be unsuccessful– Bridging shunt operation may be of benefit

• Assessment of coronary artery origin– essential to surgical planning

Prognosis

• Depends on timing

• Best outcome seen in patients repaired before the age of 5

• 90% of untreated tetralogy patients succumb by the age of 10 years

• Residual right ventricular dysfunction is common– Up to 10% of patients require re-operation within

20 years

Treatment

• Primary repair– Preferred

–usually performed at the time of diagnosis

• Palliative shunt– typically in pulmonary arterial hypoplasia

• Post-surgical complications – conduction dysfunction

– valvular dysfunction

Reference

• Haider, Ehsan A. "The Boot-shaped Heart Sign." Radiology.rsna.org. RSNA, 1 Jan. 2008. Web. 23 July 2012. <http://radiology.rsna.org/content/246/1/328.full>.

• Grainger, Ronald G. Grainger & Alison's Diagnostic Radiology. 4th ed. Vol. 1. N.p.: Churchill Livingstone, 2003. Print.

• Cukukoglu, Sardar M. "Cyanotic Diseases." Escardio.org. N.p., 2010. Web. 23 July 2012. <http://www.escardio.org/congresses/euroecho2010/Documents/teaching-course-slides/euroecho2010-cyaotic-disease-Kucukoglu-591.pdf>.

• Gallard, Frank. "Tetralogy of Fallot." Radiopaedia.org. N.p., 5 Jan. 2010. Web. 23 July 2012. <http://radiopaedia.org/images/156636>.

• "Cyanotic Heart Diseases." Learningradiology.com. N.p., n.d. Web. 23 July 2012. <www.learningradiology.com/.../cyanoticheartdz.pdf>.

• Witmer, Lawrence M. "Developmental Anatomy of the Heart and the Embryological Basis for Cardiac Defects." Ohio University, Athens. 23 July 2012. Lecture.