What are changes in st-segment, Biology

Assignment Help:

Q. What are changes in ST-Segment?

Normal Exercise Electrocardiogram ST and J Point

As the heart rate increases with exercise, a number of predictable changes occur in a normal ECG tracing. The PR-interval is shortened after 1 minute of exercise. The P-wave becomes taller and the Ta wave (wave of atrial repolarisation) increases, resulting in downward displacement of the PQ junction. This is particularly important because the so called baseline, for terms of evaluating ST-segment change, is below that usually considered to be isoelectric tracing. With exercise, the Ta wave tends to extend through the QRS and may influence that junction between the ST-segment and the T-wave.

Prognostic Significance

Asymptomatic patient-Abnormal test prevalence 5 to 12 per cent. Risk of event-9 times greater in abnormal test. 2 per cent event rate (angina) over 4 year follow up. BLS study - with risk factors- elderly patient - event rate varies 3.5 per cent to19 per cent in 9 years follow up. Females- 15 per cent to 20 per cent prevalence-less prognostic value.

Symptomatic Patient: Case Study

First stage positive: 5 per cent annual mortality, Low risk group: < 1 per cent annual mortality. It has become standard practice to use the line of PQ or PR junction as a marker for the baseline when the ST-segment is measured at one fourth the distance between the QRS and peak T in left to right leads, considerable depression is normally seen. The anterior posterior lead changes (V1 to V2) are less prominent than those in the lateral and vertical leads. The absence of significant ST-segment depression in young, vigorous boys and in athletic, middle aged men, suggests that the effect of the Ta wave, can usually be recognized because of the short duration (usually 0.045) of the J point depression.


Related Discussions:- What are changes in st-segment

How can the reactions of the nervous system be classified, Q. Concerning vo...

Q. Concerning volition of the individual how can the reactions of the nervous system be classified? The efferences (reactions) of the nervous system can be classified into volu

Define classification of carbohydrates - polysaccharides, Define classifica...

Define classification of carbohydrates - Polysaccharides? This classification is based on the number of monosaccharide units they contain, Polysaccharides are those polymers of

Why haploid cell attempted to perform meiosis, What problem would most like...

What problem would most likely to occur if a haploid cell attempted to perform meiosis? a.The cell could not replicate its DNA prior to meiosis. b.The cell could not pair hom

Kinds of succession - ecology, Kinds of Succession - Ecology The ecolo...

Kinds of Succession - Ecology The ecological succession can be broadly classified into two kinds, on the basis of the nature of the habitat. Figure: Kinds of Success

Hypertension, Define hypertension, discuss its causes and explain its effec...

Define hypertension, discuss its causes and explain its effects on the body. What role, if any, does medical imaging play in hypertensive patients? Explain and give examples.

What roles do membrane proteins play in transporting, What roles do membran...

What roles do membrane proteins play in transporting only certain substances into a cell? Some proteins form channels or pores by which certain substances can pass. Other pr

What is the auditory tube and its function, Q. What is the auditory tube an...

Q. What is the auditory tube and its function? Auditory tube (Eustachian tube) connects each middle ear to the throat. This tube conducts air between tympanic cavity and outsid

Protoplasm, physical properties of protoplasm

physical properties of protoplasm

What is the physiological cause of the syndrome, What is the physiological ...

What is the physiological cause of the syndrome known as cretinism? Cretinism is caused by chronic deficiency of the thyroid hormones (T3 and T4) during childhood. The chronic

Determine the chance of developing cancer, A typical chest x-ray exposes th...

A typical chest x-ray exposes the patient to a radiation dose of 0.01 rem. If a man receives 10 such x-rays in a lifetime, what is his chance of developing cancer as a result of th

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd