Atrial and ventricular rate response and patterns of heart rate acceleration during maternal-fetal terbutaline treatment of fetal complete heart block.
Terbutaline is used to treat fetal bradycardia in the setting of complete heart block (CHB); however, little is known of its effects on atrial and ventricular beat rates or patterns of heart rate (HR) acceleration. Fetal atrial and ventricular beat rates were compared before and after transplacental terbutaline treatment (10 to 30 mg/day) by fetal echocardiography in 17 fetuses with CHB caused by immune-mediated damage to a normal conduction system (isoimmune, n = 8) or a congenitally malformed conduction system associated with left atrial isomerism (LAI, n = 9). While receiving terbutaline, 9 of the 17 fetuses underwent fetal magnetocardiography (fMCG) to assess maternal HR and rhythm, patterns of fetal HR acceleration, and correlation between fetal atrial and ventricular accelerations (i.e., AV correlation). Maternal HR and fetal atrial and ventricular beat rates increased with terbutaline. However, terbutaline's effects were greater on the atrial pacemaker(s) in fetuses with isoimmune CHB and greater on the ventricular pacemaker(s) in those with LAI-associated CHB. Patterns of fetal HR acceleration also differed between isoimmune and LAI CHB. Finally, despite increasing HR, terbutaline did not restore the normal coordinated response between atrial and ventricular accelerations in isoimmune or LAI CHB. In conclusion, the pathophysiologic heterogeneity of CHB is reflected in the differing effect of terbutaline on the atrial and ventricular pacemaker(s) and varying patterns of HR acceleration. However, regardless of the cause of CHB, terbutaline augments HR but not AV correlation, suggesting that its effects are determined by the conduction system defect rather than the autonomic control of the developing heart.
Cuneo
Bettina F
BF
Rush Medical College, Chicago, Illinois, USA. cuneo@thic.com
Zhao
Hui
H
Strasburger
Janette F
JF
Ovadia
Marc
M
Huhta
James C
JC
Wakai
Ronald T
RT
D000318:Adrenergic beta-Agonists / Q000627:therapeutic use; D000328:Adult; D015150:Echocardiography, Doppler / Q000379:methods; D005260:Female; D005315:Fetal Diseases / Q000175:diagnosis / Q000188:drug therapy / Q000503:physiopathology; D005500:Follow-Up Studies; D006325:Heart Atria / Q000000981:diagnostic imaging / Q000196:embryology / Q000503:physiopathology*; D006327:Heart Block / Q000188:drug therapy / Q000196:embryology / Q000503:physiopathology; D006339:Heart Rate / Q000187:drug effects*; D006352:Heart Ventricles / Q000000981:diagnostic imaging / Q000196:embryology / Q000503:physiopathology*; D006801:Humans; D053798:Magnetocardiography / Q000379:methods; D008431:Maternal-Fetal Exchange / Q000502:physiology*; D011247:Pregnancy; D012189:Retrospective Studies; D013726:Terbutaline / Q000627:therapeutic use*; D016896:Treatment Outcome; D016216:Ultrasonography, Prenatal
D000318:Adrenergic beta-Agonists; D013726:Terbutaline
J Am Coll Cardiol. 1998 Jun;31(7):1658-66
9626848
Am J Obstet Gynecol. 1998 Jul;179(1):258-60
9704797
Heart Rhythm. 2005 Aug;2(8):875-86
16051128
Circulation. 2004 Sep 21;110(12):1542-8
15353508
Pediatrics. 2000 Jul;106(1 Pt 1):86-91
10878154
Gynecol Obstet Invest. 2001;52(2):142-4
11586045
Circulation. 1995 Dec 15;92(12):3394-6
8521558
Obstet Gynecol. 1977 Feb;49(2):247-51
834412
Circulation. 1978 Jan;57(1):163-71
618385
Circulation. 1979 May;59(5):879-85
428099
Am J Cardiol. 1986 Aug 1;58(3):291-4
3090867
Pacing Clin Electrophysiol. 1987 Sep;10(5):1058-70
2444930
J Am Coll Cardiol. 1992 Oct;20(4):904-10
1527300