Assessment of fetal atrioventricular time intervals by tissue Doppler and pulse Doppler echocardiography: normal values and correlation with fetal electrocardiography

Abstract

Objective: To establish gestational age-specific reference values of normal fetal atrioventricular (AV) time interval by spectral tissue Doppler imaging (TDI) and pulse-wave Doppler (PD) methods, and to assess their correlation with signal-averaged fetal PR intervals (ECG). Design: Cohort study. Setting: Tertiary centre for fetal cardiology. Patients and measures: 131 pregnant women between 14 and 42 weeks' gestation underwent 196 fetal echocardiograms and 158 fetal ECG studies. TDI-derived AV intervals were measured as the intervals from atrial contraction (Aa) to isovolumic contraction (IV) and from Aa to ventricular systole (Sa) at the right ventricular free wall. PD-derived AV intervals were measured from simultaneous left ventricular inflow/outflow (in/out) and superior vena cava/aorta (V/AO) recordings. Results: Measurements were possible by ECG in 61%, by TDI in 100%, by in/out in 100% and by V/AO in 97% of examinations. Aa-IV correlated significantly better with PR intervals (y = 0.67x + 38.29, R 2 = 0.15, p , 0.0001, mean bias 8.0 ms) than did in/out (R 2 = 0.10, p = 0.002, bias 18.7 ms) and V/AO (R 2 = 0.06, p = 0.02, bias 12.4 ms). Gestational age and AV intervals were positively correlated with all imaging modalities (R 2 = 0.19-0.31, p , 0.0001). Conclusion: This study showed the feasibility of fetal AV interval measurements by TDI, and established gestational age-specific reference data. TDI-derived Aa-IV intervals track ECG PR intervals more closely than PD-derived AV intervals and thus should be used as the ultrasound method of choice in assessing fetal AV conduction. I solated congenital complete atrioventricular (AV) block is associated with maternal anti-Ro/SSA and anti-La/SSB autoantibodies, which may trigger inflammatory destruction of the AV node in the susceptible fetus. Related to this insult, electrical AV conduction is progressively prolonged to complete heart block at around 20 weeks' gestation. Complete AV block may be preventable if the disease can be recognised and treated at an early stage of AV nodal damage, which is clinically characterised by a short-lived appearance of first-or second-degree AV block.1 2 Thus, a simple, precise diagnostic tool that allows reliable detection of subtle electrical AV conduction anomalies is indispensable for the surveillance of at-risk fetuses.Although recording fetal electrophysiological signals is possible by transabdominal fetal magnetocardiography and signal-averaged ECG, 3-5 their use is limited to a few centres. Alternatively, simultaneous pulse-wave Doppler (PD) interrogation of the mitral valve and left ventricular inflow/ outflow (in/out) or the superior vena cava/ascending aorta (V/AO) have been used to study the chronology of atrial and ventricular systolic events indirectly by their mechanical consequences.6-11 The accuracy of measurements of flowderived AV time intervals is influenced by loading condition, intrinsic myocardial properties, heart rate and the speed of pulse-wave propagation. [12][13][14] In addition, there is a tendency...

Early Diagnosis and Treatment of Atrioventricular Block in the Fetus Exposed to Maternal Anti-SSA/Ro-SSB/La Antibodies

“…The accuracy of TVI-based measurement for AV interval has also been demonstrated recently by Nii et al 42 In fact, using the same TVI technique we had described previously, 22 Nii et al 42 measured an average normal AV interval of 94Ϯ8 ms, which is almost identical to the AV interval we measured in the 109 normal fetuses in the present study (89Ϯ8 ms). Obviously, one cannot rely on the presence of first-degree AVB after birth to evaluate the present findings, because the present study was interventional, and we treated fetuses that showed increased PR intervals in consecutive FKCGs in utero.…”

“…Nii et al 42 reported that attainment of a fetal ECG is not feasible after 28 weeks of gestation because of the distribution of the vernix caseosa, and the fetal ECG p wave is poorly defined, which renders this methodology inadequate for accurate AVC measurement. In addition, ECG was feasible in only 61% of the cases.…”

Diagnosis and Treatment of Fetal Cardiac Disease

“…14,16,95 The mechanical PR interval has been measured in fetuses at risk with the use of a variety of M-mode and pulsed Doppler techniques and compared with gestational age-adjusted normal values. 96 Although the value of serial assessment for the detection of the progression of myocardial inflammation or conduction system disease from first-degree block (PR prolongation) to CHB has not been proved, serial assessment at 1-to 2-week intervals starting at 16 weeks and continuing through 28 weeks of gestation is reasonable to perform because the potential benefits outweigh the risks. For women who have had a previously affected child, more frequent serial assessment, at least weekly, is recommended.…”

Fetal Echocardiography and Prenatal Cardiovascular Interventions – An Update (2012)

“…Lack of effective fetal ECG techniques and limited availability of fetal magnetocardiography has resulted in ongoing dependence upon Doppler and m mode-based techniques that define the onset and relationship of mechanical atrial and ventricular systole from which associated electrophysiological events can be inferred. Through the use of pulsed Doppler with simultaneous left ventricular inflow and outflow, superior vena cava and ascending aorta [45] and pulmonary venous and pulmonary arterial [46] recordings, as well as simultaneous tissue Doppler interrogation of atria and ventricles [1,2], we have learned to better define arrhythmia mechanism ( Figure 5). Fetal supraventricular tachyarrhythmias can now be classified as long and short V-A (ventricular-atrial, corresponding with electrophysiological long and short R-P) tachycardias, atrial flutter or junctional ectopic tachycardia.…”

“…Although the mainstay of our field applied routinely in practice has been that of high-resolution two-dimensional imaging with harmonic capabilities and Doppler interrogation of blood flow, several newer modalities promise to optimize our investigation of the fetal heart in the future. These include tissue Doppler and speckle tracking applications that define subtle abnormalities of heart rhythm and function [1][2][3][4], and 3 and 4 dimensional imaging which potentially enhances detection and definition of structural cardiac pathology and assists in the evaluation of functional abnormalities [5][6][7][8][9][10].…”