What is intracoronary and intracerebral hypertension ?
Posted Nov 18 2008 12:10am
A normally functioning circulatory system is vital for our survival . We have about 6000 ml of blood, circulating all over the body in an approximate time of 15-20 seconds.The pressure at which this blood moves across the body is called the blood pressure . Hypertension or simply , high blood pressure is an undesirable hemodynamic disturbance in human circulatory system.Systemic hypertension is the most common type of hypertension. The blood pressure is primarily dependent on the status of the blood vessel(vascular resistance) and cardiac contractility. This regulation is under many neural and hormonal factors.Further the blood pressure varies depending upon the blood vessel calibre, and the local milieu.There is a progressive drop in blood pressure from major arteries to the small arteries .The pressure drop is maximum across the arterioles to reach the venules .The venous circulation has the lowest pressure, it ends up at right atrium with a mean pressure of 0- 5mmhg.
Importance of regional variation of blood pressure.
It should be realised , each organ has it’s own regulated blood pressure.The brain perfuses by the intracerebral pressure .The lungs decide how much should be the pulmonary arterial pressure.The kidney not only controls it’s own pressure but also has a major regulatory role in systemic pressure by rennin angiotensin system.The examples are numerous, portal system has it’s unique pressure controlling hepatic hemodynamics. The retinal blood vessels regulate intra ocular pressure. While the human circulatory system has a wide variation of blood pressure across the breadth and length of vascular system, it is ironical a single snap shot BP with a brachial cuff is used to define the normality and if it is normal every thing is thought to be hunky dory!
It is widely acknowledged now , aging of humanity is nothing but aging of our vascular system
So we should have new parameters to assess individual organ’s vascular health as well as the currently popular systemic vascular health. The single important factor that determine coronary endothelial damage is the intra coronary pressure.It is never taken into account in any of the cardivascular mortality studies. This is the prime reason for the widely prevalent conflict in the cardiology literature , namely : Controlling systemic blood pressure has poor correlation with cardiovascular outcome. Many of the so called normotensive individuals have serious hemodynamic injury in their coronary arteries.This was made apparent in the ASCOT LLA study , in which patients with near normal blood pressure also benefited from statin therapy , implying endothelial damage could occur at any level of systemic blood pressure.
What is the normal intracoronary pressure ? When do you diagnose intracoonary hypertension?
The normal intracoronary pressure is around 40mmhg . Intra coronary hypertension as a clinical entity is yet to be recognised . There is no defintion available for intracoronary HT , intracerebral hypertension as well.
It’s still a long way to go , for the cardiology and neurology community to assess non invasively intracoronary pressures and intra cerebral arterial pressure to prevent coronary events ant strokes.
Simple risk prediction using brachial cuff blood pressure is a grossly unscientific method (Sorry, i really mean it ) to assess one’s vascular health.There has been few attempts like vascular endothelial health assessment by fore arm blood flow , central aortic pressure (Instead of brachial cuff pressure) as an index for risk predictment and assessment for hypertension is suggested.