Thursday, June 16, 2011

Dr Kiran welcomes you to the new post of blog.

It is often told that thinking is easier than writing! However, I have found the contrary to be true. In the past 30 odd months of single focus blogging, I have found better expression with writing than verbalizing the same issue. All this is to tell the readership that writing comments is good – for yourself and for the blogger!!

Let us dwell into the interesting learning scenarios right away:

WHY COLLATERALS?

In post-Glenn status, it is not uncommon to find venovenous collaterals. How common is the development of new aorto-pulmonary collaterals during post-Glenn? We had an 11-year-old girl with such a picture. Her pressure data was normal and she also had good-sized branch Pas. However, she had leash of new aorto-pulmonary collaterals which was not found during the previous cath study. We know the impetus for venovenous collaterals – usually the dissipation of pressure. What is the impetus for new AP collaterals when the pulmonary arteries and saturations are OK? Is there any other impetus for development of new AP collaterals other than cyanosis? To best of what we have seen, this finding is infrequent. I would be interested in finding experiences and inputs from readers.

NEED OF HOMOGRAFT

This was a good learning. We had a 6-year-old with Tetralogy of Fallot with absent Right Pulmonary artery. On cath, we found the right lung supplied by three high pressure collaterals from thoracic aorta at T5-6 level. An innovative looking surgery was suggested by our senior consultant – resecting the collateral portion of aorta en masse, unifocalizing that segment with existing pulmonary artery and interposing a graft for the resected aortic segment. However, the surgical team was not keen on this, as the complexity of surgery would be higher for no better yield. It was decided that the lesion is overall repairable with unifocalization and intracardiac repair. The question was the need for homograft. It was successfully argued that the unifocalized high pressure collaterals would require competent valve. A transannular patch in such cases would result in torrential regurgitation due to high afterload. It was a good “retrograde” learning!

STABLE BLUE BOY

When we discuss the differentials of hemodynamically stable, asymptomatic blue toddlers, we often describe the utility of murmur. The general rule is, better the murmur – stabler the patient, as the bottomline in these cases are extent of pulmonic stenosis. For example, a toddler with tetralogy of Fallot with good murmur over left upper sternal border has better hemodynamic stability than the one without murmur. For, murmur indicates blood flow across the narrow RVOT. The exceptions to this rule are few. We had a toddler with uniform saturation of 76% in all limbs. He was totally asymptomatic- barring the only complaint: cyanosis. The arterial blood gases showed low pO2 and marginally high pCO2. His physical examination did not reveal any significant finding. Cyanosis and clubbing were confirmed. He had normal heart sounds and no murmur. Chest radiograph was normal. There was no reason to suspect cardiac cause of cyanosis. On echo, we found the issue. The SVC was opening totally into LA, without any ASD! There was no LSVC. IVC was normally into RA. All the pulmonary veins were opening into LA. Surprisingly, the LA and LV dimensions were normal. How these tougher chambers accommodated the extra blood without getting dilated was enigmatic! This was the first time I saw a partial anomalous systemic venous connection. I had earlier seen Raghib complex, but this one was new. The management is simple, but the presentation was puzzling and findings were not in mould! After a painful delineation of diagnosis, we found an outside report wherein they had not only diagnosed the problem, but had also done a saline contrast injection in the upper limb, documenting the entry of SVC flow into LA. Good show indeed! We searched the literature and found only 19 reported cases so far. Most of them had associated anomaly. This is probably one among very few cases of isolated RSVC to RA without any other cardiac anomaly.

BREEDING THE NEED

This is not the problem of one centre; virtually every centre I have come across have this problem – some more some less, but inevitably, yes. I am talking about the unnecessary diagnostic cath studies performed in our country. It is accepted that Pediatric cardiology is still young field and rigid consensus are not possible yet. But, many times, those children who have their decision written very well on clinical grounds end up getting diagnostic cath studies. Whether it is ignorance or felt-need or greed or breeding the culture of teaching the evidence to trainees is questionable. We do come across patients carrying reports and CDs wherein the cath study was done for absolutely useless indications. Consider these examples: 7-month-old child with failute to thrive, saturating 98% in room with large VSD. Another child with truncus arteriosus where one cannot get either the numerator or denominators of the equations to calculate cath data. Worse of the lot is when the consensus is made based on chest radiograph and ECG after a thorough cath study! Isn’t it possible to create an institutional consensus on the need for cath? Many centres do a combined cardiologist-surgeon cath meetings to discuss the decisions. Isn’t it time to do a pre-cath meet to decide the utility of cath study in individual cases? I strongly feel that everyone owes the responsibility of passing on scientific knowledge to those who look upon us. I have tried to bring up this issue many times, but the futility is obvious every time. I would like to hear experiences and thoughts of readers on this issue.

FATE OF THE UNPAIRED

I have brought up this issue once in the past, but this time it was bigger. We evaluated a 22-year-old DORV, VSD, PS who had undergone a BD Glenn shunt at an outside hospital in 2009 (at age of 20 years)! On enquiry, we understood that the earlier centre had planned a two-pump repair on her, but found the VSD to be non-routable. Hence, they took on table PA pressures and performed a Glenn shunt instead. However, she came back with no improvement in saturations or effort tolerance. Her baseline SO2 was 70%. We did the cath study in our centre. Her PA mean pressure was 12mmHg. However, we found a hugely dilated azygous vein entering the SVC. We balloon occluded the azygous to notice the increase in PA mean pressure to 14mmHg. Her IVC was not interrupted. Her EDP was 10mmHg. The question was: why did the azygous vein dilated so much? The lower body is well drained by the IVC. The PA pressures are acceptable. How did the azygous dilate at all? Normally, the azygous vein gets ligated during BD Glenn shunt. But here,http://www.blogger.com/img/blank.gif the previous centre had not done that. It is true that the azygous would behave like a pop-off, but can it dilate so much in the absence of any impetus? Is it only the pro-gravity phenomenon wherein the SVC blood finds it easier to drain into azygous than to PA? Are there venous valves in azygous? Please let me know your experiences on this.

That brings us to the end of present post. Please pen your criticisms and suggestions in the comments box or direct them to my email: drkiranvs@gmail.com See you shortly with few more learning scenarios.

Regards

Kiran