Congenital Heart

7/29/2019 Congenital Heart

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STUDY OF PEDIATRIC CONGENITAL CARDIAC

MALFORMATIONS BY ECHOCARDIOGRAPHY


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ANATOMICAL CLASSIF ICATIONThe ventricular septum may be dividedinto a small membranous portion{Perimembranous defects are mostcommon (70%)}, and a large muscularportion. The muscular septum has three

components: the inlet septum, thetrabecular septum (also simply calledmuscular septum), and the outlet(infundibular or conal) septum. Thetrabecular septum is further divided

into anterior, posterior, middle, andapical portions.


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Echocardiography

Two-dimensional and Doppler echo studies can identifythe number, size, and exact location of the defect;estimate PA pressure by using the modified Bernoulli

equation; identify other associated defects; andestimate the magnitude of the shunt. Because theventricular septum is a large, complex structure,examination for a VSD should be carried out in a

systematic manner to be able to specify the exactlocation and size of the defect. When possible, morethan one view should be obtained, preferably acombination of the long- and short-axis views.


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In patients with VSD right ventricular pressure can bedetermined noninvasively by subtracting the VSD-gradient from the systolic blood pressure. Using astand-alone continuous-wave Doppler the VSD-gradient may be underestimated due to a large angletheta caused by the various VSD locations and theoften atypical VSD-jet directions. Therefore Color-Doppler was used to visualize the VSD-jet and to align(angle less than 15 degrees) the continuous-waveDoppler beam.


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Transducer position: leftsternal edge; 2nd 4thintercostal space

Marker dot direction: pointstowards right shoulder


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Apical 4-Chamber View (AP4CH)Transducer position: apexof heart

Marker dot direction:points towards leftshoulder

The AP5CH view isobtained from this view

by slight anteriorangulation of thetransducer towards thechest wall. The LVOT canthen be visualised


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Apical 4-Chamber View (AP4CH


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SubCostal 4 Chamber View(SC4CH)

Transducer position:apex of the heart

Marker dot direction:

points towards leftside of neck (450anticlockwise fromAP4CH view)

Good for assessment

ofLV anterior wall

LV inferior wall


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Doppler echocardiographyDoppler echocardiography is a method fordetecting the direction and velocity ofmoving blood within the heart.

Pulsed Wave (PW) useful for low

flow e.g. MV flow- measure specific bloodflow by placing the sampling volume at theregion of enters

Continuous Wave (CW) useful for highvelocity flow e.g aortic stenosis

Color Flow (CF) Different colors are used todesignate the direction of blood flow. red isflow toward, and blue is flow away fromthe transducer with turbulent flow shownas a mosaic pattern.


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Continuous Dopplerwill measure allvelocities along theultrasound beam: Thebeam is transmittedcontinuously, and thereceived echoes aresampled continuously

with no range gating.


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CF DopplerCF Doppler is a pulsed wave signal with a color valueassigned to the received signal, which is superimposedon a 2D image. A higher frequency flow toward thetransducer is expressed in shades of red and lowerfrequency f low away from the transducer in shades ofblue.

CF can be used in the diagnosis of abnormal blood flowbetween two structures including ventricular septaldefects (VSD)


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In the image on the lower panel , CFDoppler confirms abnormal blood f lowthrough the defect.


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Echocardiographic profile in ventricular septal defect

Ventricular septal defect

(subaortic) seen from

parasternal long axis

viewParasternal long axisview showing aorta

(Ao), left atrium (LA),

left ventricle (LV) and a

small perimembranous

(subaortic) ventricular

septal defect. Mitral

valve is in the open

position and the aortic

valve in the closed

position.


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VSD Jet visualised by colour flow mapping (colour

Doppler)

Colour sector inparasternal long axisview shows the mosaic(multi-coloured) VSD jet

across theperimembranous VSDfrom the left ventricle tothe right ventricle. It is ahigh velocity jet becausethe VSD is restrictive.The neck of the jetalmost corresponds tothe size of the VSD. VSDjet is seen in a systolicframe.


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Continuous wave Doppler interrogation of VSD jet

VSD jet can be picked up in parasternallong axis or short axis view, guided bycolor Doppler. It may also be picked upfrom the apical four chamber view, butthe allignment may not be good.

Pulsed Doppler cannot measure the jetvelocity as it is much higher than theNyquist limit of the pulsed Dopplersystem. Hence continuous waveDoppler is used for interrogation ofthe VSD jet. The interventriculargradient is calculated using theBernoulli equation. A highinterventricular gradient indicates thatthe VSD is restrictive. A low gradientindicates unrestrictive VSD andpulmonary hypertension.


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Medium sized ventricular septaldefect in peri-membranous locationseen from the apical five chamber

view. RV: right ventricle; LV: leftventricle; VSD: ventricular septaldefect; Ao: aorta; RA: right atrium;LA: left atrium; IVS: interventricularseptum. There is aneurysm of theinteverventricular septum covering

the VSD, leaving a small gap. TheVSD jet passes through this smalldefect which is restrictive (below).


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VSD jet documented by

Doppler interrogation,showing an interventriculargradient of 61.5 mm Hg,which suggests that the defectis restrictive. Actual gradientmay be even more as this jet

has an incomplete envelope.


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LVRA shunt in perimembranous VSD across STL fenestration

the jet from the left ventricle to the right ventricle across the

perimembranous VSD

parasternal short axis

view of flow from the

left ventricule to right

ventricle, in theclassical location of a

perimembranous VSD.


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Congenital Heart