UOG Journal Club: October 2011 Pulsed-wave tissue Doppler echocardiography for the analysis of fetal cardiac arrhythmias B. 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 45 Cardiac 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 the analysis 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 the analysis 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 wall movements 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 the analysis 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 the analysis 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 the analysis 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 premature atrial 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 the analysis 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 (*) 2 nd 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 the analysis 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 detectedBlood flow (in the peripheral lung vessels) AV annulus motion (one step closer to the actual electromechanical basis) Segments interrogatedTwo (simultaneous pulmonary artery and vein) One (AV annulus) Dependence on fetal position Mostly independentDependent (apical insonation angle is mandatory) Visualization of intracardiac structures Mostly unnecessaryNecessary (AV annulus) Special hard- or software?No Pulsed-wave tissue Doppler echocardiography for the analysis 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 against a background of low or absent venous velocities in different phases of the cardiac cycle) Complete AV block (A’ can be obscured by the “stronger” S’ if they coincide) Pulsed-wave tissue Doppler echocardiography for the analysis 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 the analysis of fetal cardiac arrhythmias Tutschek and Schmidt, UOG 2011