Sinusoidal heart rate pattern: Reappraisal of its definition and clinical significance

Abstract

Objectives: To address the clinical significance of sinusoidal heart rate (SHR) pattern and review its occurrence, define its characteristics, and explain its physiopathology. Background: In 1972, Manseau et al. and Kubli et al. described an undulating wave form alternating with a flat or smooth baseline fetal heart rate (FHR) in severely affected, Rh-sensitized and dying fetuses. This FHR pattern was called 'sinusoidal' because of its sine waveform. Subsequently, Modanlou et al. described SHR pattern associated with fetal to maternal hemorrhage causing severe fetal anemia and hydrops fetalis. Both Manseau et al. and Kubli et al. stated that this particular FHR pattern, whatever its pathogenesis, was an extremely significant finding that implied severe fetal jeopardy and impending fetal death. Undulating FHR pattern: Undulating FHR pattern may be due to the following: (1) true SHR pattern; (2) drugs; (3) pre-mortem FHR pattern; (4) pseudo-SHR pattern; and (5) equivocal FHR patterns. Fetal conditions associated with SHR pattern: SHR pattern has been reported with the following fetal conditions: (1) severe fetal anemia of several etiologies; (2) effects of drugs, particularly narcotics; (3) fetal asphyxia/hypoxia; (4) fetal infection; (5) fetal cardiac anomalies; (6) fetal sleep cycles; and (7) sucking and rhythmic movements of fetal mouth. Definition of true SHR pattern: Modanlou and Freeman proposed the following definition for the interpretation of true SHR pattern: (a) stable baseline FHR of 120-160 bpm; (b) amplitude of 5-15 bpm, rarely greater; (c) frequency of 2-5 cycles per minute; (d) fixed or flat short-term variability; (e) oscillation of the sinusoidal wave from above and below a baseline; and (f) no areas of normal FHR variability or reactivity. Physiopathology: Since its early recognition, the physiopathology of SHR became a matter of debate. Murata et al. noted a rise of arginine vasopressin levels in the blood of posthemorrhagic/anemic fetal lamb. Further works by the same authors revealed that with chemical or surgical vagotomy, arginine vasopressin infusion produced SHR pattern, thus providing the role of autonomic nervous system dysfunction combined with the increase in arginine vasopressin as the etiology. Conclusion: SHR is a rare occurrence. A true SHR is an ominous sign of fetal jeopardy needing immediate intervention. The correct diagnosis of true SHR pattern should also include fetal biophysical profile and the absence of drugs such as narcotics. Key words: fetal anemia, pre-mortem heart rate pattern, pseudo-sinusoidal heart rate pattern, sinusoidal heart rate pattern.

Dynamics of the Formation of Rhythmic Activity of the Heart in Fetuses and Newborn Rats

“…In 60% fetuses, marked periodic changes in RR-intervals presented by slow oscillations with a duration of 20-35 msec at amplitude of 10-45 msec were observed; they were most regular when the fetus is motionless (Fig.1, a). Similar sinusoidal oscillations of cardiac rhythm with a frequency of 2-5 per minute sometimes occur in human fetuses and are considered as an indicator of severe fetal pathology [5,9]. During movement, the oscillations persist, but their regularity is disturbed (Fig.…”

Vasa praevia: a case report and literature review

“…Since this area has a low degree of vascularisation, with the growth of the uterus, the placenta in the uterus is moved toward a better vascularised area, the remaining placental tissue on the cervix atrophies and only umbilical cord blood vessels attached to the membranes remain (1, 2). Also, the scholars describe a number of vasa praevia risk factors: membranous umbilical cord anchorage, additional segments of the placenta (two or more), a low-attached low placenta or placenta praevia, twins, assisted reproduction procedures (9). The main risk factors are membranous cord anchorage and the multi-segmental placenta (5).…”

Rythme cardiaque fœtal pendant le travail : définitions et interprétation

“…Il n'est pas toujours aisé de repérer le RCF de base en cas d'accélération ou de ralentissement prolongé par exemple, et une étude sur plusieurs cycles de dix minutes peut être nécessaire [14] Le rythme sinusoïdal D'abord décrit pendant la grossesse [16], l'aspect sinusoï-dal du RCF est rare et répond aux critères de Modanlou et Murata [17] : le rythme de base est stable (110-160 bpm), les oscillations régulières, d'amplitude de 5 à 15 bpm et de fréquence entre 2 à 5 cycles/min, la variabilité fixe, minime ou absente. La sinusoïde décrite est symétrique par rapport à la ligne de base et il n'existe aucun épisode normal ou réactif.…”