vulnerable period


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period

 [pēr´e-od]
an interval or division of time; the time for the regular recurrence of a phenomenon.
absolute refractory period the part of the refractory period from phase 0 to approximately −60 mV during phase 3; during this time it is impossible for the myocardium to respond with a propagated action potential, even with a strong stimulus. Called also effective refractory period.
blanking period a period of time during and after a pacemaker stimulus when the unstimulated chamber is insensitive to avoid sensing the electronic event in the stimulated chamber.
effective refractory period absolute refractory period.
ejection period the second phase of ventricular systole (0.21 to 0.30 sec), between the opening and closing of the semilunar valves, while the blood is discharged into the aorta and pulmonary artery. Called also sphygmic period.
gestation period see gestation period.
incubation period see incubation period.
isoelectric period the moment in muscular contraction when no deflection of the galvanometer is produced.
latency period
latent period a seemingly inactive period, as that between exposure to an infection and the onset of illness (incubation period) or that between the instant of stimulation and the beginning of response (latency, def. 2).
refractory period the period of depolarization and repolarization of the cell membrane after excitation; during the first portion (absolute refractory period), the nerve or muscle fiber cannot respond to a second stimulus, whereas during the relative refractory period it can respond only to a strong stimulus.
relative refractory period the part of the refractory period from approximately −60 mV during phase 3 to the end of phase 3; during this time a depressed response to a strong stimulus is possible.
safe period the period during the menstrual cycle when conception is considered least likely to occur; it comprises approximately the ten days after menstruation begins and the ten days preceding menstruation. See the section on fertility awareness methods, under contraception.
sphygmic period ejection period.
supernormal period in electrocardiography, a period at the end of phase 3 of the action potential during which activation can be initiated with a milder stimulus than is required at maximal repolarization, because at this time the cell is excitable and closer to threshold than at maximal diastolic potential.
vulnerable period that time at the peak of the T wave during which serious arrhythmias are likely to result if a stimulus occurs.
Wenckebach's period a usually repetitive sequence seen in partial heart block, marked by progressive lengthening of the P–R interval; see also dropped beat.

vul·ner·a·ble pe·ri·od

, vulnerable period of heart
a brief time during the cardiac cycle when stimuli are particularly likely to induce repetitive activity like tachycardia, flutter, or fibrillation which persists after the stimulus has ceased; for the ventricle, it occurs during the latter part of systole, during the relative refractory period coincident with the inscription of the latter half of the T wave of the electrocardiogram.

vulnerable period

a short period in the cardiac cycle during which activation may result in an ectopic beat. The ventricular vulnerable period corresponds to the apex of the T wave toward its ascending side.

vul·ner·a·ble pe·ri·od

, vulnerable period of heart (vŭlnĕr-ă-bĕl pērē-ŏd, hahrt)
Moment during the cardiac cycle when stimuli are particularly likely to induce repetitive activity like tachycardia, flutter, or fibrillation that persists after the stimulus has ceased; for the ventricle, it occurs during the latter part of systole, during the relative refractory period coincident with the inscription of the latter half of the T wave of the electrocardiogram.
References in periodicals archive ?
In 1968, Dobbing (1) suggested that there were vulnerable periods of neurological development that coincided with times of maximal brain growth.
Brigade watch manager Steve Johnson who devised the scheme with Eleanor Burns, patient services manager, said: "This particular long-term working practice will help individuals who may be at a very high risk following hospitalisation, enabling us to assist them during this vulnerable period.
A lightning rod for the commission during a vulnerable period," TR helped to institutionalize the hitherto "precarious and ill-supported experiment" of civil service (p.
Before an audience of around 1,000 participants, both midwives and obstetricians, this initiative was taken on, in the context of Africa, where still so many women and children die during that vulnerable period of their lives.
Such information about the living con-ditions of this particular age group people will allow to orientate the actions to generate better levels of wellbeing and to eliminate and reduce gender inequi-ties in a vulnerable period.
By narrowing the vulnerable period to the third trimester of pregnancy, the scientists have come up with "a novel finding," says Mark A.
To mitigate problems arising from this mismatch in cognitive-emotional abilities and social pressures, the balanced support, monitoring, and modeling of social roles by influential adults (known as social scaffolding) can help guide and protect the adolescent through this vulnerable period.
That Leodine, in L'ancetre noir, happens to be an adolescent, as was Leopold in Mixed Blood, isn't accidental, for it is at that vulnerable period of one's life that social traits take form and a child's personality is molded.
There is a condition called commotio cordis in which a sharp blow directly to the chest at a very vulnerable period of the cardiac cycle does cause death.
Be careful about bumping into a computer, particularly during the vulnerable period when it first boots.
That almost guarantees piglets will make it through half of their most vulnerable period.
8 Number of goals lost by Celtic in the final 15 minutes of the match makes that their most vulnerable period