uog journal club: october 2011 pulsed-wave tissue doppler echocardiography for the analysis of fetal...

UOG Journal Club: October 2011Pulsed-wave tissue Doppler echocardiography for the

analysis of fetal cardiac arrhythmiasB. Tutschek and K. G. Schmidt

Volume 38, Issue 4, Date: October 2011, pages 406–412

Journal Club slides prepared by Dr Aly Youssef(UOG Editor for Trainees)

• Precise evaluation of the type and mechanism of a fetal arrhythmia is mandatory in order to define prenatal treatment options and prognosis

• Fetal arrhythmias may lead to fetal cardiac failure, hydrops and death

Background

Background: Current assessment of fetal arrythmias

M-mode•High temporal resolution•Dependent on fetal position•May require multiple attempts to acquire appropriate tracings

Pulsed-wave Doppler of blood flow

(e.g. at the pulmonary artery/vein)

•Displays diastolic and systolic flow events in one recording•Mostly independent of fetal position•Different pulsed-wave propagation times may interfere with the analysis of electromechanical coupling

Pulsed-wave tissue Doppler echocardiography

(current study)

Patients:100 fetuses

15–40 weeks referred for cardiac evaluation

45Cardiac arrhythmias

55 Normal anatomy and function

• All fetuses had a complete fetal echocardiographic examination before entry into the study• Axial excursions of the ventricular wall at the atrioventricular (AV) valve annulus were recorded

using PW-TDE• Both PW-TDE and pulsed-wave Doppler of the blood flow through the AV valves were recorded

simultaneously in several of the normal fetuses (in order to study the temporal correlation between flow and tissue signals)

Objective: To study normal and abnormal fetal cardiac rhythm using pulsed-wave tissue Doppler echocardiography (PW-TDE)

Pulsed-wave tissue Doppler echocardiography for theanalysis of fetal cardiac arrhythmias

Tutschek and Schmidt, UOG 2011

Several different high resolution ultrasound systems equipped for prenatal or neonatal studies, but without specific tissue Doppler probes or software

Ultrasound system

↓ Pulse repetition frequency (PRF) (to about ± 15 cm/sec)

↓ Wall filter (minimum)

↓ Receive gain (to remove blood flow signals)

Ultrasound settings

• The heart is imaged in an apical (or close to apical) insonation angle • Pulsed Doppler sample volume adjusted in size and placed over the area covering the

entire valve annulus excursion during systole and diastole• Data acquired during fetal and maternal apnea and absence of fetal body movements

Technique



Methods

Results: Correlation with blood flow Doppler

tissue Doppler (TD) signals

blood flow Doppler signals

mitral inflow, aortic outflow / left ventricular TD

tricuspid inflow / right ventricular TD

Note that blood flow and wallmovements are

synchronous, but run in opposite directions

The temporal relation of PW-TDE and conventional blood flow Doppler signals

was depicted in such tracings, confirming the interpretation

of the PW-TDE signals



Early diastole

Away from the apex

Towards the apex

Late diastole

Isovolumetric contraction

Isovolumetric relaxation

Systole



Results: Normal pattern of PW-TDE

• Best signal-to-noise ratio was usually obtained from right ventricular wall (tricuspid valve annulus)

• Separate E’ and A’ were often seen, followed by S’

• Fusion of E’ and A’ occurred if rates are > 130bpm

Results: PW-TDE in fetal arrhythmias



• Atrial activity (A’) is regular

• Interval preceding PVC (dashed red bar)

plus post-ectopic interval (solid red bar)

equals interval between two normal sinus

beats (white bar) i.e. compensatory pause

• In post-ectopic pause (post PVC), E’ and A’

are separate

• Atrial activity is irregular due to PAC

• Absence of systolic excursion (S’)

after PAC (non-conducted)

• Interval between pre- and post-ectopic

atrial activation is shorter than the

expected interval between two normal

beats (non- compensatory pause)

Non-conducted prematureatrial contraction (PAC)

Conducted premature atrial contraction (PAC)

• PAC is followed by systolic

excursion (&)

• Conducted PAC shows an early

atrial activation with associated

ventricular response (&), but also a

non- compensatory pause

Premature ventricular contractions (PVC)

Results: PW-TDE in fetal arrhythmias



Supraventricular tachycardia (SVT)

• E’ and A’ (below baseline) always coincided

• There was a 1:1 association of atrial and ventricular motion

• There was progressive lengthening of conduction time in successive cardiac cycles until ventricular response was skipped (*)

2nd degree atrioventricular block, type Wenckebach

• There were regular atrial activations (A), but much more rapid and dissociated ventricular contractions (S)

Ventricular tachycardia with AV dissociation

Results: PW-TDE of complete fetal atrioventricular block

Ventricular contractions

Atrial contractions

Atrial activations obscured by ventricular activation

Atrial activity immediately after ventricular emptying (large amplitude)

Atrial activation occurring after S’, associated with separation of E’ and A’



Pulsed-wave Doppler of blood flow

(e.g. in the pulmonary vessels, Carvalho et al., Heart 2007)

Pulsed-wave tissue Doppler echocardiography

(Tutschek and Schmidt, UOG 2011)

Movement detected Blood flow (in the peripheral lung vessels)

AV annulus motion(one step closer to the actual

electromechanical basis)

Segments interrogated Two(simultaneous pulmonary artery

and vein)

One(AV annulus)

Dependence on fetal position

Mostly independent Dependent(apical insonation angle is

mandatory)

Visualization of intracardiac structures

Mostly unnecessary Necessary(AV annulus)

Special hard- or software? No No



Discussion: Comparison with pulsed-wave blood flow Doppler

Pulsed wave Doppler of blood flow in the pulmonary vessels

(Carvalho et al., Heart 2007)

Pulsed wave Tissue Doppler echocardiography

(Tutschek and Schmidt , UOG 2011)

Arrythmias with a difficult assessment

Complete AV block(due to difficulty in recognizing the

‘‘A’’ wave againsta background of low or absent venous velocities in differentphases of the cardiac cycle)

Complete AV block(A’ can be obscured by the

“stronger” S’ if they coincide)



In this case M-mode proved to offer complementary help to both techniques

Conclusion• The study demonstrated that high-resolution ultrasound systems for fetal imaging without specific hard- or software can be used for the recording of tissue motion and detailed characterization of fetal arrhythmias• The study provided detailed descriptions of normal PW-TDE recordings and provided examples of PW-TDE recordings in common fetal arrhythmias• The study showed potential of PW-TDE for estimating AV conduction time, depicting directly tissue movement

These findings may improve the ability to analyze precisely fetal arrhythmias and to select appropriate therapeutic options



uog journal club: october 2011 pulsed-wave tissue doppler echocardiography for the analysis of fetal...

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