Chairman of Clinical & Preventive Cardiology
Medanta The Medicity, Gurgaon
Today to discuss a very important topic central aortic pressure, you are one of the top most experts in the country and even the world wide very widely recognized for your work on central aortic pressure. So to begin with sir, can you let us know what is happening in this area?
It is a good question. Thank you very much for inviting me here. Central aortic pressure if I may use alkalization it is central to hypertension, in what way that the pressure which is generated by left ventricle and when it first hits the aorta is the pressure which does target organ damage that can cause damage to the brain, it can cause damage to the heart and of course traveling down to the kidneys. So the recognition of this central aortic pressure becomes important to us. With this, let me qualify that brachial artery pressure is not going pout of fashion in a hurry, no it will continue, but for high-risk individuals those who are diabetics, those who are young smokers coronary artery disease, central aortic pressure assumes importance because you will then be able to tailor the drugs meant to decrease the central aortic pressure. For example there are drugs, which will decrease the blood pressure peripherally and you are quite satisfied well. I have got this patient’s blood pressure down to 130/80 and yet he continues to have higher incidence of stroke why because another drug which also which also brought it down to 130/80 actually acted on the central aortic pressure so that is one of the key things of importance in recognition of central aortic pressure and accepting that this is a reality. This is one of the key things. The second thing that emanates from this is pulse wave velocity that means when the heart contracts the blood goes down from carotids to the femorals, you get something called the pulse wave velocity and it was more than 1200 cm per sec then you know that the patient is going to get arterial stiffness. Arterial stiffness what it will do then is that it will cause left ventricle hypotrophy cause rude on the heart, decrease the diastolic filling and will cause all the things which you do not want your high blood pressure patient to have. So arterial stiffness, pulse wave velocity, central aortic pressure in a sense are all together, but recognition of pulse wave velocity and central aortic pressure will give you an idea of arterial stiffening, which is the core now. You remember many years ago Thomas Sydenham said “a man is as old as his arteries.” This is it. Now, we can measure it and mind all this is totally noninvasive. This is just by applanation tonometry. So you are not doing any intervention to the patient.
Yes, we have brought a very interesting point here now, so there are invasive ways to measure them and there are non invasive ways to measure them. How do they correlate as the non invasive, measure been validated against the invasive measures.
Ya, let me tell you, that there are very few invasive methods, you can take the central aortic pressure by a catheter but the reverberations of that as the pulse wave goes to the periphery cannot be recorded by any invasive procedure. Also see when you take a patient to the cath lab circumstances are different. His pressures will be higher. He will have tachycardia all these things will happen. So it is not the usual run-of-the-mill. So I think these things have been now taking care of. There is good correlation and people are accepting the use of noninvasive technique, so if your asking are they 04:00 well validated? Yes, they are at least the periscope and other instruments are well validated.
Ya that of the one of the point, which I was asking how accurate they are how validated they are so that can a physician rely on the reading which they get.
Yes of course.
So you mentioned about there are certain high risk individuals in which they are mandatory. Can you please throw us more light on those individuals.
Particularly if I have a young hypertensive with diabetes, I would definitely at some point do once or twice his ambulatory BP monitoring and at least once a central aortic pressure to see how much his arteries are thickened. Also it is a very important point you have raised, some of these equipments also give us a measurement of the ankle brachial index. The same instrument will tell you of the ABI. Now the ABI is supposed to be very closely correlated with the incidence of the coronary artery disease just as pulse wave velocity very interestingly last year there is an article from Israel, a study of 17,000 people and not all hypertensive. So it is a wrong thing to just think in terms of high blood pressure and pulse flow velocity. These are patients who are not hypertensive, but had very good correlation with the occurrence. So it is not only a disease marker, but it also an event marker because by observation studies we say o well, No, you can actually qualify about the events that are likely to occur, if your pulse wave velocity is high and if you have arterial stiffness. The main importance of the study actually came about with the CAFE study in which ACE inhibitors and amlodipine were found to decrease incidents of strokes and heart failure rather then a beta-blocker based therapy and that where the people started thinking look all drugs are not the same though they are bring down the pressure to the same level so that is where the people started thinking can I do something better so answer your question high risk individual should have this. Now in my hypertension lab, we are also saying that when the patient first comes to us and we detect hypertension so we do not start medications immediately, but if the central aortic pressure is already elevated and if he is already getting arterial stiffness, if the pulse wave velocity is high what are we waiting for, then we have enough justification to start the therapy. Otherwise, we would say ok come back again or do an ABPM, but the side effects are already there and the LVH is ready there you start treatment. So that, in effect, is the total gamut of pulse wave velocity and its importance as it is emerging now more and more people are recognizing the importance.
One of the questions which is coming in my mind now is that 07:00 physicians are used to measuring brachial blood pressure and you mentioned that it is going to stay. So if the physician is measuring a brachial blood pressure reading and also seeing a central aortic pressure reading is there a correlation or what to do best
Yes that again is, now many a times patients comes to us they say your therapy was excellent, but I am feeling very weak. We measure the pressure, the pressure is 120/80, it is all related to the central aortic pressure and the central aortic pressure is just 110 so many a times we can pick up patients who are either not controlled or who are in a sense over controlled. So you can do a lot of things for these patients. Also mind you these patients show isolated systolic hypertension, you can pickup for them central aortic pressure it is extremely important and what therapy you will give.
Any particular nay data from India. Any studies you have done in Indian patients are they different in the western population or.
Other studies are there in fact as I was seeing that our studies intima-media thickness, ankle brachial index are actually 15 years old already and these studies has come out in the general of clinical Cardiology, where we have correlated that all right you forget everything., if you have pulse wave velocity and intima-media thickness and calcium score which is the best indicator for disease because Felmingham does not work with us, CCHA does not work with us and WHO pool does not work with us and we found that the patient may not be able to afford a calcium score, but if we can afford even a central aortic pressure, pulse wave velocity within intima-media thickness it gives a very good indication of coronary artery disease. Ultimately, this is what you are looking at your looking at stroke and heart attacks. Central aortic pressure correlates directly to cognitive disturbance as well. So that why we are using currently and our work was and one day we had the good luck of having Dr. John Cockcroft from Cardiff who was one of the pioneers of the central aortic pressure and he was very impressed he said you know that this will be probably the only lab where Indian data is accumulating now. So we are closely working as many groups.
You have already touched already touched point briefly that how it is changing the management as well. Can you throw us little more light on if the physicians start measuring and looking at central aortic pressure. How it is wearing the way they manage the hypertension.
Yes, I think if physician at large because everybody is supposed to take blood pressure, if physicians at large start doing it, I am sure we will see fewer strokes and fewer heart failure because heart failure and the commonest reasons is hypertension and we have lesser ventricular hypertrophies, less coronary artery disease because now the patient will say the brachial artery may be fine central aortic pressure is still high let me give him medication and let me give him drugs, which will effectively effect the central aortic pressure.
That brings a very interesting point so are the drugs various classes of drugs different in the way they act at central aortic pressure.
Yes, there are drugs , which will act differently for example ACE inhibitors for example act on the central aortic pressure, amlodipine, I am telling you this is an remarkable drug acts on the central aortic pressure. The role of beta-blockers is diminishing, but people say that may be labetalol has a good action, but having said that I think the main emphasis will be on amlodipine and ACE inhibitors to really bring down the central aortic pressure to the levels that you want and at that level patient should be able to do all his normal work and not feel weakness, fatigue or tiredness. So I think we are on to that level.
You mentioned that all this we are doing primarily because we are trying to prevent a heart attack or trying to prevent a stroke. So is there any data for ACE inhibitor and calcium channel blockers, which shows that they have a better out come as compared to other class of therapy
Yes absolutely, I refer to the case study then the BPL arm of the Escorts study, clear data, this was study about ARB and amlodipine and then there was a good data from perindopril with amlodipine, very good data. So I think ACE inhibitors, there is a resurgence in our own thinking about t because we should give medication not for the sake of just giving a medication, but that the has a whole some effect right started from the kidneys to the brain. Cognitive disorders, we always overlook, in India they say “ye tho 60 saal ka hogaye, satiyagaye, bhool jathe hain logonke naam.” No that is because he is getting microinfarcts you have not been able to correct the pressure here. So the brain is open to elevations of pressure and these troughs and peaks are the once which cause the problem.
So within the central aortic pressure like we talk about the brachial pressure it has systolic and diastolic pressure. In the same way is there correlation between systolic and diastolic and central aortic pressure?
That also is there and that is important because if the returning is from the periphery, comes in systole then you will get augmented systolic pressure and you will get the augmentation index which is better for the heart, but if the returning wave comes in diastole than it helps my patient because that is where the coronary is get filled, coronaries are peculiar. They will only get filled during diastole and that is in effect the genesis of isolated systolic hypertension of the elderly people call it. The returning wave because of the stiffened arteries come to the central aortic pressure during systolic so it raises that pressure further and therefore increases the pulse pressure, which what we are measuring here and that is I mean you know ISH is such a devastating disease.
You also mentioned that brachial blood pressure some patients are getting under treated and some patient are actually getting over treated.
Over treated yes.
Some high risk patients what are they going to see with the doses. Are the doses as the large going to increase or increase any data.
I don’t know what comes out, but yes we have decreased doses in some patients.
Physicians wanted to ask is what are the normal values, are there any guidelines and recommendations on normal value?
They are actually coming out now. I tell you, recently given out guidelines by the European Hypertension Society are actually talking of central aortic pressure they are talking about use of echocardiography for these patients. So I may not be able to give you a clear answer t this point, but I tell you people are working both in India as well as abroad to answer this question that some times the brachial my be higher and central aortic may be lower or the other way round. Intuitively I would want the central aortic pressure to be below 130/80 or140/80 in diabetic patients naturally below that point. If you look at the pressure curve that comes out from this tracing you will be able to convince yourself that your getting both systolic and diastolic and both in the brachial as well as in the central. So please rest assured that it needs more study on a bigger database. We already have people working on it and we will be able to decide for this, but yes, at this point I could not write off because our work right now has more focused on how I can use this tool for early detection. My focus has been on that, but of course foci keep changing and this is one of our focus to really get to the integrity of central aortic pressure and I think you have raised many important points to which there are no clear answers right now, but the answers will be emanating. It is a science which is just coming up allover the world actually, but it is good that India has taken not he lead, but at least India is not far behind in this because we have to have methods for early detection.
Thank you so much for this. It is really interesting and promising area and we all look forward that some more advances happen and it really helps us in deciding therapies better and improving the outcomes of the patient.