Describe coronary spasm, Biology

Assignment Help:

Q. Describe Coronary Spasm?

Usually spasm develops at the site of subcritical or critical stenoses, but it may also occur in angiographically normal coronary arteries, the so called variant form of angina. Occlusive spasm causes transmural ischaemia with ST-segment elevation, but when spasm is subocclusive, it may cause subendocardial ischaemia and ST-segment depression.

Coronary Collateral Circulation

1) The drop in poststenotic pressure caused by flow-limiting stenoses stimulates the development of collateral circulation from other coronary artery beds. The supply of collateral blood flow increases poststenotic pressure, thus improving coronary flow reserve and raising the ischaemic threshold.

2) Collateral vessels develop from the progressive enlargement of preexisting intercoronary arterial anastomoses.

3) Blood flow through these anastomeses begins as a consequence of the flow-limiting stenosis when a pressure gradient develops between their origin and termination.

4) In unanesthetized dogs, a pressure gradient of about 10mm Hg, caused by a lumen reduction of 70 to 80 per cent has been shown to elicit the development of collateral flow.

5) Preexisiting anastomoses progressively transform to vessels with a final diameter of 20 to 200 um.

6) Blood flow through collaterals is determined by the driving pressure and by their resistance, which is influenced by neural and humoral stimuli and by local vasoactive autacoids.

7) In patients, heparin and fibroblastic growth factor 1 (FGF-1) have been suggested to promote collateral growth.


Related Discussions:- Describe coronary spasm

Circulatory fluid in the body of cockroach, Can all the four chambers of th...

Can all the four chambers of the human heart experience systole simultaneously? Describe justifying your answer. What do you call the circulatory fluid in the body of cockroach

Determine some guidelines for cancer prevention, Determine Some Guidelines ...

Determine Some Guidelines for Cancer Prevention? The guidelines for cancer prevention focus on the following: 1. Include plant-based diet, limiting red meat in particular.

Effect of insulin on metabolism of carbohydrate, The foods we take have thr...

The foods we take have three basic ingredients - carbohydrate, protein and fat. Insulin has profound effects on the metabolisms of carbohydrate, protein and fat. Metabolism helps o

Protozoa, what are the disadvantages of protozoa

what are the disadvantages of protozoa

Define incision - endodontic surgery, Define Incision - Endodontic Surgery ...

Define Incision - Endodontic Surgery Incisions are accomplished by using one of four scalpel blades: No. 11, No.  12, No. 15, and No. 15-C Horizontal incision should be m

Illustrate the electrophysiology and ion transport of cornea, Illustrate th...

Illustrate the electrophysiology and ion transport of cornea? Electrophysiology and ion transport of cornea: The trans-epithelial potential is 25-35 mV. It is almost 50 p

Factors that affects oxygen dissociation curves, Factors that affects Oxyge...

Factors that affects Oxygen Dissociation Curves Oxygen dissociation curve for a sample of blood is affected by several factors. The most important of them are: Te

Scrapie, Scrapie This is a chronic fatal disease of sheep and occasiona...

Scrapie This is a chronic fatal disease of sheep and occasionally of goats caused by a Prion agent similar to BSE. The disease is reported from Europe, North America and in a f

Write out electronic configuration, Give number of valence electrons for te...

Give number of valence electrons for technetium. Write out electronic configuration for the valence electrons. Give the number of valence electrons and the number of electronic con

What is the tympanum, What is the tympanum? In which part of the ear is it ...

What is the tympanum? In which part of the ear is it located and what is its function? The tympanum (or ear drum) is a membrane located in the middle ear just after the auditor

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