| premature systole | A premature contraction of the heart that is independent of the normal rhythm and arises in response to an impulse in some part of the heart other than the sinoatrial node. Synonym: premature beat. (18 Nov 1997) |
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| premature ventricular contraction | <cardiology> A cardiac arrhythmia which originates from within the ventricles. Isolated ventricular contractions are referred to as premature ventricular contractions. Frequent premature ventricular contractions can be potentially unstable and can degrade to a more serious rhythm or cardiac arrest. Acronym: PVC (31 Dec 1997) |
| premature ventricular contractions | Contractions of the lower chambers of the heart, the ventricles, which occur earlier than usual, because of abnormal electrical activity of the ventricles. The premature contraction is followed by a pause, as the heart electrical system resets itself and the contraction following the pause is usually more forceful than normal. These more forceful contractions are frequently perceived as palpitations. (12 Dec 1998) |
| infant, premature | An infant born before 38 weeks of gestation. (12 Dec 1998) |
| ovarian failure, premature | Premature failure of ovulation associated with hypergonadotropinism and hypoestrogenism in women under the age of 40. The aetiology appears to be multifactorial and many cases are idiopathic. When follicles are present but the ovaries are unable to respond to gonadotropins, resistant ovary syndrome results and this may be associated with autoimmune disease. Even when there is a loss of ovarian follicles, it is not always complete. Permanent and irreversible loss of follicles is termed premature menopause (menopause, premature). (12 Dec 1998) |
| labour, premature | Onset of labour before term but after the foetus has become viable, usually sometime during the 29th through 38th week of gestation. (12 Dec 1998) |
| foetal membranes, premature rupture | Spontaneous rupture of amniotic sac before the onset of uterine contractions. (12 Dec 1998) |
| anterior condyloid foramen | The canal through which the hypoglossal nerve emerges from the skull. Synonym: canalis hypoglossalis, anterior condyloid canal of occipital bone, anterior condyloid foramen. (05 Mar 2000) |
| anterior palatine foramen | An opening in the posterolateral corner of the hard palate opposite the last molar tooth, marking the lower end of the pterygopalatine canal. Synonym: foramen palatinum majus, anterior palatine foramen. (05 Mar 2000) |
| aortic foramen | The opening in the diaphragm bounded by the two crura, the vertebral column, and the median arcuate ligament, through which pass the aorta and thoracic duct. Synonym: hiatus aorticus, aortic foramen, aortic opening. (05 Mar 2000) |
| apical dental foramen | The opening at the apex of the root of a tooth that gives passage to the nerve and blood vessels. Synonym: foramen apicis dentis, apical dental foramen, root foramen. (05 Mar 2000) |
| apical foramen of tooth | The opening at the apex of the root of a tooth that gives passage to the nerve and blood vessels. Synonym: foramen apicis dentis, apical dental foramen, root foramen. (05 Mar 2000) |
| arachnoid foramen | The large midline opening in the posterior inferior part of the roof of the fourth ventricle, connecting the ventricle with the cerebellomedullary cistern. Synonym: apertura mediana ventriculi quarti, arachnoid foramen, Magendie's foramen, median aperture of the fourth ventricle. (05 Mar 2000) |
| Bichat's foramen | <anatomy, vein> An expansion of the subarachnoid space extending forward between the corpus callosum and the thalamus; it encloses the internal cerebral veins which caudally join to form the vena magna cerebri (Galen's vein). Synonym: ambient cistern, Bichat's canal, Bichat's foramen, cistern of great vein of cerebrum, cisterna ambiens, cisterna superioris, cisterna venae magnae cerebri, superior cistern. (05 Mar 2000) |
| blind foramen of frontal bone | <anatomy> Blind or caecal foramen of the frontal bone; the blind foramen formed immediately anterior to the crista galli by a notch at the lower end of the frontal crest and its articulation with the ethmoid bone. It is insignificant postnatally, but gives passage to vessels during development. Synonym: foramen caecum ossis frontalis, blind foramen of frontal bone, caecal foramen of frontal bone. (05 Mar 2000) |