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
Pulsed-wave tissue Doppler echocardiography for theanalysis of fetal cardiac arrhythmias
Tutschek and Schmidt, UOG 2011
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
Pulsed-wave tissue Doppler echocardiography for theanalysis of fetal cardiac arrhythmias
Tutschek and Schmidt, UOG 2011
Early diastole
Away from the apex
Towards the apex
Late diastole
Isovolumetric contraction
Isovolumetric relaxation
Systole
Pulsed-wave tissue Doppler echocardiography for theanalysis of fetal cardiac arrhythmias
Tutschek and Schmidt, UOG 2011
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
Pulsed-wave tissue Doppler echocardiography for theanalysis of fetal cardiac arrhythmias
Tutschek and Schmidt, UOG 2011
• 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
Pulsed-wave tissue Doppler echocardiography for theanalysis of fetal cardiac arrhythmias
Tutschek and Schmidt, UOG 2011
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 tissue Doppler echocardiography for theanalysis of fetal cardiac arrhythmias
Tutschek and Schmidt, UOG 2011
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
Pulsed-wave tissue Doppler echocardiography for theanalysis of fetal cardiac arrhythmias
Tutschek and Schmidt, UOG 2011
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)
Pulsed-wave tissue Doppler echocardiography for theanalysis of fetal cardiac arrhythmias
Tutschek and Schmidt, UOG 2011
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
Pulsed-wave tissue Doppler echocardiography for theanalysis of fetal cardiac arrhythmias
Tutschek and Schmidt, UOG 2011