Wednesday, January 1, 2014

Dr Kiran welcomes everyone again to the blog of Pediatric cardiology department of Narayana Hrudayalaya.

I have always been partial towards history! When I wrote history of pediatric cardiology in the earlier posts of this blog, a sense of fulfillment was experienced. After all, we are seeing better horizons of science standing on the shoulders of few giants. We should at least know the owners of those shoulders!

I am thinking of introducing those seminal articles and studies which have laid the foundation of pediatric cardiology. Many of them are more than 50 years old! When we talk of some classification or algorithm, we actually do not know the reference. Few learnings just pass on from one generation of students to the next, without even bothering to know who was the original thinker! My idea is to introduce one such article per post. It will not be an exhaustive review, but a brief introduction to ignite!

In this post, I will make a beginning with a fine article, which has stood the test of time for its accuracy.

Questions on the natural history of Patent Arterial Duct (PDA) are very commonly asked in rounds, bedside clinics and examinations. But, how many of us can actually quote the reference? I am referring to “Natural History of persistent ductus arteriosus” by Dr Maurice Campbell, published in British Heart Journal in 1968. Dr Campbell was the first editor of British Heart Journal.

The article starts off with practical difficulties in assessing the natural history of congenital heart diseases in contrast to that of an infection or infarction. Then, it briefs the readers short historical aspects and fast changing trends in the management of PDA.

Spontaneous closure of PDA beyond infancy is discussed with inputs from personal experiences, followed by mortality rates in PDA from time to time. Since many patients of PDA had already reached the age of 20 years or more, the article discusses the effect of operations in such patients.

An interesting aspect of the article is the discussion on the expectations of life for those with PDA. The author has then collected data on necropsies done for PDA patients and has compared the mortalities. Ages of living patients on the data from clinics of three physicians is also given.

The author has taken care to draw his own logical inputs in calculating the incidence of bacterial endocarditis in the PDA cohort and puts it at less than 1% per annum. A passing reference is made to the gender incidence of PDA, but no discussion on why it is universally high in girls.

The article ends with a lucid summary and author drawn conclusions. Few of them are as follows:
• As the years pass, more physicians will be advising operation for a persistent ductus arteriosus with no personal experience of its natural course without operation. It seems important that someone who has seen this period of change should record as much as possible before it is too late. The rate of mortality and the likelihood of other changes in persistent ductus arteriosus can be expressed correctly only when the numbers at risk and the years for which they were under observation are both known.
• We have calculated that the ductus closes spontaneously in 0-6 per cent per annum. Probably the rate is fairly constant, at least for the first four decades. This does not sound very much, but means that 20 ± 3 per cent will have closed by the age of 60. This is our most important conclusion, but it does not mean that an operation which gives a normal expectation of life should be deferred, unless there is already evidence that the duct is closing.
• About the time the first decade changes to the second, the risk of bacterial endocarditis increases to at least 0 45 per cent per annum, and this continues for 40 years or more.
• By the age of 30, our calculations show that about one-fifth of the subjects will have died. From the fourth decade onwards these changes are progressively severe, with a mortality rate rising from 2-5 to 4-0 per cent per annum. By 45, about 42 per cent will have died
• By 60, over 60±10 per cent will have died and the duct will have closed in 20 ± 3 per cent. The article is reminiscent of the commitment of the previous generation to science and future academicians. Reading the entire article is strongly recommended.

One can find the full article free in the following link. 
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC459200/

That brings us to the interesting leaning scenarios of this post. 

LEFT AND RIGHT 

One interesting observation we have made is the early onset of PAH in children with ASD with bilateral SVC. I have written about this combination in the past, speculating that the dilated coronary sinus may act as possible obstruction to mitral valve inflow, simulating Lutembacher physiology, causing PAH. The question was, does physiological mitral valve obstruction occur in post-operative scenarios of this variant or in children with isolated persistence of LSVC? We have not come across such scenarios. I would like to know the experiences of readers in this regard. 

TIGHTENING THE FLOW 

In cases of single ventricle palliation, surgeons prefer to do pulmonary artery tightening when the PA pressures are marginally ore than required. Theoretically, this works. However, we have seen that the effect is much superior in younger age group. How to explain this? Does the amount of smooth muscle in the vasculature matter? Is there a role of plasticity here? How consistent are the observations in different age groups? It would be interesting to know the opinions from readers. 

VALVE AGAINST NO VALVE 

Many centers have approached the problem of free PR in transannular patches. Many surgeons have attempted monocusp, bicusp or tricusp valves made of different materials. Although the results in immediate post-operative periods are good, I don’t know if anybody has done a study on long term results. I would like to know the experience of those centres which consistently use such interventions and their long term results. Please share. 

PERIPHERAL PROBLEMS 

How to approach peripheral pulmonary artery stenosis? The problem is consistent with or without shunts, although the outcome is much better in the former group. It is very depressing to see the CT scans reporting multiple constrictions in the entire length of visible pulmonary arteries. What medications are useful? The problem is very common with syndromic associations. Is that a problem in non-syndromics also? Very less data is available because not many of them would see the OT table. Please share your experiences. 

END TO BETA-BLOCKADE 

In children with recovered dilated cardiomyopathies, when to stop beta-blockers? Is resumption of normal EF the end-point? Should we wait for the LV to come back to normal size? Should ACE inhibitors be continued? I have not come across any guidelines on this. Please share your individual opinions and references if any. 
That brings us to the end of this post. Please write in your comments. If you find any problem in posting comments, please feel free to mail it to my emial id kiran.vs.dr@nhhospitals.org I shall post them on your behalf. 

 Regards 

Kiran

3 comments:

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  2. Thank you Sir for bringing pack the historical papers. Regarding PDA closure, silent PDAs need not to be closed, but many of them are being intervened. If the incidence of IE is low, does it make sense in closing it or is it being done as the procedure is simple and with minimal risks...?

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    1. Thank you for the quesry, Dr Dhanya.
      Silent PDAs are incidental detections as the name itself suggests. As per the guidelines, they need not be closed. Paradoxically, most of them are so small that they are indeed difficult to close! So, going by evidence, they can be left alone. But most of the times, the parents would not wish to retain anything that sounds abnormal! For that reason, the silent PDAs are intervened sometimes. Scientific fraternity should be very careful in such situations, as any catastrophe would not be taken kindly when the indication is not a standardised one.

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