{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,28]],"date-time":"2026-08-28T23:35:17Z","timestamp":1787960117479,"version":"build-2784847793"},"reference-count":51,"publisher":"Ovid Technologies (Wolters Kluwer Health)","issue":"4","content-domain":{"domain":["www.ahajournals.org"],"crossmark-restriction":true},"short-container-title":["Circ: Arrhythmia and Electrophysiology"],"published-print":{"date-parts":[[2018,4]]},"abstract":"<jats:sec>\n                    <jats:title>Background:<\/jats:title>\n                    <jats:p>Long-QT syndrome (LQTS), an inherited cardiac repolarization disorder, is an important cause of fetal and neonatal mortality. Detecting LQTS prenatally is challenging. A fetal heart rate (FHR) less than third percentile for gestational age is specific for LQTS, but the sensitivity is only \u224850%. Left ventricular isovolumetric relaxation time (LVIRT) was evaluated as a potential diagnostic marker for fetal LQTS.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods and Results:<\/jats:title>\n                    <jats:p>\n                      LV isovolumetric contraction time, LV ejection time, LVIRT, cycle length, and FHR were measured using pulsed Doppler waveforms in fetuses. Time intervals were expressed as percentages of cycle length, and the LV myocardial performance index was calculated. Single measurements were stratified by gestational age and compared between LQTS fetuses and controls. Receiver-operator curves were performed for FHR and normalized LVIRT (N-LVIRT). A linear mixed-effect model including multiple measurements was used to analyze trends in FHR, N-LVIRT, and LV myocardial performance index. There were 33 LQTS fetuses and 469 controls included. In LQTS fetuses, the LVIRT was prolonged in all gestational age groups (\n                      <jats:italic>P<\/jats:italic>\n                      &lt;0.001), as was the N-LVIRT. The best cutoff to diagnose LQTS was N-LVIRT \u226511.3 at \u226420 weeks (92% sensitivity, 70% specificity). Simultaneous analysis of N-LVIRT and FHR improved the sensitivity and specificity for LQTS (area under the curve=0.96; 95% confidence interval, 0.82\u20131.00 at 21\u201330 weeks). N-LVIRT, LV myocardial performance index, and FHR trends differed significantly between LQTS fetuses and controls through gestation.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions:<\/jats:title>\n                    <jats:p>The LVIRT is prolonged in LQTS fetuses. Findings of a prolonged N-LVIRT and sinus bradycardia can improve the prenatal detection of fetal LQTS.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1161\/circep.117.005797","type":"journal-article","created":{"date-parts":[[2018,4,13]],"date-time":"2018-04-13T05:15:51Z","timestamp":1523596551000},"update-policy":"https:\/\/doi.org\/10.1161\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":42,"title":["Left Ventricular Isovolumetric Relaxation Time Is Prolonged in Fetal Long-QT Syndrome"],"prefix":"10.1161","volume":"11","author":[{"given":"Sally-Ann B.","family":"Clur","sequence":"first","affiliation":[{"name":"Departments of Pediatric Cardiology, Obstetrics and Gynecology, and Cardiology, Academic Medical Center, Amsterdam, The Netherlands (S.-A.B.C., A.S.V., P.G.R.d.M., A.A.W., N.A.B.). Department of Pediatric Cardiology, University of Utah &amp; Primary Children\u2019s Hospital, Salt Lake City (S.P.E.). Department of Clinical Sciences, Pediatrics, Ume\u00e5 University, Sweden (A.R.). Department of Cardiology, Mayo Clinic, Rochester, MN (M.J.A.). Department of Pediatrics, Medical College of Wisconsin, Milwaukee (D..."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Arja S.","family":"Vink","sequence":"additional","affiliation":[{"name":"Departments of Pediatric Cardiology, Obstetrics and Gynecology, and Cardiology, Academic Medical Center, Amsterdam, The Netherlands (S.-A.B.C., A.S.V., P.G.R.d.M., A.A.W., N.A.B.). Department of Pediatric Cardiology, University of Utah &amp; Primary Children\u2019s Hospital, Salt Lake City (S.P.E.). Department of Clinical Sciences, Pediatrics, Ume\u00e5 University, Sweden (A.R.). Department of Cardiology, Mayo Clinic, Rochester, MN (M.J.A.). Department of Pediatrics, Medical College of Wisconsin, Milwaukee (D..."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Susan P.","family":"Etheridge","sequence":"additional","affiliation":[{"name":"Departments of Pediatric Cardiology, Obstetrics and Gynecology, and Cardiology, Academic Medical Center, Amsterdam, The Netherlands (S.-A.B.C., A.S.V., P.G.R.d.M., A.A.W., N.A.B.). Department of Pediatric Cardiology, University of Utah &amp; Primary Children\u2019s Hospital, Salt Lake City (S.P.E.). Department of Clinical Sciences, Pediatrics, Ume\u00e5 University, Sweden (A.R.). Department of Cardiology, Mayo Clinic, Rochester, MN (M.J.A.). Department of Pediatrics, Medical College of Wisconsin, Milwaukee (D..."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Pascale G.","family":"Robles de Medina","sequence":"additional","affiliation":[{"name":"Departments of Pediatric Cardiology, Obstetrics and Gynecology, and Cardiology, Academic Medical Center, Amsterdam, The Netherlands (S.-A.B.C., A.S.V., P.G.R.d.M., A.A.W., N.A.B.). Department of Pediatric Cardiology, University of Utah &amp; Primary Children\u2019s Hospital, Salt Lake City (S.P.E.). Department of Clinical Sciences, Pediatrics, Ume\u00e5 University, Sweden (A.R.). Department of Cardiology, Mayo Clinic, Rochester, MN (M.J.A.). Department of Pediatrics, Medical College of Wisconsin, Milwaukee (D..."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Annika","family":"Rydberg","sequence":"additional","affiliation":[{"name":"Departments of Pediatric Cardiology, Obstetrics and Gynecology, and Cardiology, Academic Medical Center, Amsterdam, The Netherlands (S.-A.B.C., A.S.V., P.G.R.d.M., A.A.W., N.A.B.). Department of Pediatric Cardiology, University of Utah &amp; Primary Children\u2019s Hospital, Salt Lake City (S.P.E.). Department of Clinical Sciences, Pediatrics, Ume\u00e5 University, Sweden (A.R.). Department of Cardiology, Mayo Clinic, Rochester, MN (M.J.A.). Department of Pediatrics, Medical College of Wisconsin, Milwaukee (D..."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Michael J.","family":"Ackerman","sequence":"additional","affiliation":[{"name":"Departments of Pediatric Cardiology, Obstetrics and Gynecology, and Cardiology, Academic Medical Center, Amsterdam, The Netherlands (S.-A.B.C., A.S.V., P.G.R.d.M., A.A.W., N.A.B.). Department of Pediatric Cardiology, University of Utah &amp; Primary Children\u2019s Hospital, Salt Lake City (S.P.E.). Department of Clinical Sciences, Pediatrics, Ume\u00e5 University, Sweden (A.R.). Department of Cardiology, Mayo Clinic, Rochester, MN (M.J.A.). Department of Pediatrics, Medical College of Wisconsin, Milwaukee (D..."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Arthur A.","family":"Wilde","sequence":"additional","affiliation":[{"name":"Departments of Pediatric Cardiology, Obstetrics and Gynecology, and Cardiology, Academic Medical Center, Amsterdam, The Netherlands (S.-A.B.C., A.S.V., P.G.R.d.M., A.A.W., N.A.B.). Department of Pediatric Cardiology, University of Utah &amp; Primary Children\u2019s Hospital, Salt Lake City (S.P.E.). Department of Clinical Sciences, Pediatrics, Ume\u00e5 University, Sweden (A.R.). Department of Cardiology, Mayo Clinic, Rochester, MN (M.J.A.). Department of Pediatrics, Medical College of Wisconsin, Milwaukee (D..."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nico A.","family":"Blom","sequence":"additional","affiliation":[{"name":"Departments of Pediatric Cardiology, Obstetrics and Gynecology, and Cardiology, Academic Medical Center, Amsterdam, The Netherlands (S.-A.B.C., A.S.V., P.G.R.d.M., A.A.W., N.A.B.). Department of Pediatric Cardiology, University of Utah &amp; Primary Children\u2019s Hospital, Salt Lake City (S.P.E.). Department of Clinical Sciences, Pediatrics, Ume\u00e5 University, Sweden (A.R.). Department of Cardiology, Mayo Clinic, Rochester, MN (M.J.A.). Department of Pediatrics, Medical College of Wisconsin, Milwaukee (D..."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"D. Woodrow","family":"Benson","sequence":"additional","affiliation":[{"name":"Departments of Pediatric Cardiology, Obstetrics and Gynecology, and Cardiology, Academic Medical Center, Amsterdam, The Netherlands (S.-A.B.C., A.S.V., P.G.R.d.M., A.A.W., N.A.B.). Department of Pediatric Cardiology, University of Utah &amp; Primary Children\u2019s Hospital, Salt Lake City (S.P.E.). Department of Clinical Sciences, Pediatrics, Ume\u00e5 University, Sweden (A.R.). Department of Cardiology, Mayo Clinic, Rochester, MN (M.J.A.). Department of Pediatrics, Medical College of Wisconsin, Milwaukee (D..."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ulrike","family":"Herberg","sequence":"additional","affiliation":[{"name":"Departments of Pediatric Cardiology, Obstetrics and Gynecology, and Cardiology, Academic Medical Center, Amsterdam, The Netherlands (S.-A.B.C., A.S.V., P.G.R.d.M., A.A.W., N.A.B.). Department of Pediatric Cardiology, University of Utah &amp; Primary Children\u2019s Hospital, Salt Lake City (S.P.E.). Department of Clinical Sciences, Pediatrics, Ume\u00e5 University, Sweden (A.R.). Department of Cardiology, Mayo Clinic, Rochester, MN (M.J.A.). Department of Pediatrics, Medical College of Wisconsin, Milwaukee (D..."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mary T.","family":"Donofrio","sequence":"additional","affiliation":[{"name":"Departments of Pediatric Cardiology, Obstetrics and Gynecology, and Cardiology, Academic Medical Center, Amsterdam, The Netherlands (S.-A.B.C., A.S.V., P.G.R.d.M., A.A.W., N.A.B.). Department of Pediatric Cardiology, University of Utah &amp; Primary Children\u2019s Hospital, Salt Lake City (S.P.E.). Department of Clinical Sciences, Pediatrics, Ume\u00e5 University, Sweden (A.R.). Department of Cardiology, Mayo Clinic, Rochester, MN (M.J.A.). Department of Pediatrics, Medical College of Wisconsin, Milwaukee (D..."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Bettina F.","family":"Cuneo","sequence":"additional","affiliation":[{"name":"Departments of Pediatric Cardiology, Obstetrics and Gynecology, and Cardiology, Academic Medical Center, Amsterdam, The Netherlands (S.-A.B.C., A.S.V., P.G.R.d.M., A.A.W., N.A.B.). Department of Pediatric Cardiology, University of Utah &amp; Primary Children\u2019s Hospital, Salt Lake City (S.P.E.). Department of Clinical Sciences, Pediatrics, Ume\u00e5 University, Sweden (A.R.). Department of Cardiology, Mayo Clinic, Rochester, MN (M.J.A.). 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