Pediatric Heart Expert Forum
double switch surgery or not
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double switch surgery or not

my 12 year old son has congenitally corrected transposition of the great artery...so far it is asymptomatic, although the tricuspid valve shows very minor leaking. My son is checked annually by his heart doctor & at this past checkup, the doctor suggested that I start to think about the double switch surgical procedure as an option to consider. Here are my questions:

What is the number of double switch surgeries performed annually & what are outcomes?
Should this procedure be considered even though the corrected TGA is asymptomatic?
Is this procedure best done when the patient is still young?
Since the left ventricle is pumping blood to the lungs with more pressure, can this affect the lungs?
Where else should I be looking in order to find out more about this procedure and my son's condition?

Naturally, I'm torn between subjecting my son to major surgery on the one hand and doing nothing on the other hand, realizing that complications may very well occur as he gets older. Any advice you can give would be greatly appreciated.
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773637_tn?1327450515
Dear Jnani,

For our other readers, congenitally corrected transposition of the great arteries, also referred to as “l-transposition” or “l-TGA”, occurs when the ventricles are switched.  This means that blood from the right atrium flows into a left ventricle, which then goes into the main pulmonary artery (MPA), through the lungs, to the left atrium, down into a right ventricle, and out to the body.  The blood flow through the heart goes to where it needs to go BUT the ventricles are “inverted”, which means that structurally you have the wrong “types” of ventricles doing the wrong type of work.  The pressure on the right side of the heart is low, and a normal right ventricle is designed for low pressure work.  Certainly, the inverted left ventricle, as designed for high pressure work, can handle it.  However, the right ventricle on the high pressure left side is not architecturally ready for its long term work to pump blood out to the body.  Over time, the left-sided morphologic right ventricle gets thicker, as all muscles do when dealing with higher resistance, but it also dilates.  With further dilation, it leads to a volume load that stretches the tricuspid valve (in this case, the valve between the LEFT atrium and the ventricle), causing it to leak.  As it leaks, it adds more of a volume load onto the ventricle.  Also, as the ventricle dilates, it compresses the right-sided left ventricle, which makes it hard for the heart to pump to the lungs as well.  All of this leads to congestive heart failure and poor cardiac output to the body.

There have been many approaches to this problem, including medications to try to decrease the left-sided volume loading, placing a band on the pulmonary artery to restrict flow the MPA (which increases right sided pressure, pushes back on the left-sided ventricle, and decreases the volume load), transplantation, and the “double-switch”.  A double-switch occurs when two surgical interventions are used.  The first is a Senning procedure, in which the atria are surgically baffled, or directed, across to the opposite ventricles.  In other words, the blood from the right atrium is directed across to the left-sided right ventricle and the blood from the left atrium is directed across to the right-sided left ventricle.  The second part of the switch then also moves the great arteries (the MPA and the aorta) plus the coronary arteries to their correct ventricles, so that the MPA arises now from the left-sided right ventricle and the aorta (and coronary arteries) arise from the right-sided left ventricle.  What this does is get the blood to the appropriate chambers and vessels, so you’d think everything was fixed.  But…it’s not all great.  First of all, it can be difficult to get the untrained right-sided left ventricle that has been working at low pressure for all of these years to suddenly start working at high pressure.  Typically, surgeons will place a band on the MPA to try to “train” the ventricle, although it is not known over the long term whether this gives a good quality result for the ventricle.  Second, it is extensive surgery within the atria to create the baffles, which leads to lots of scarring.  These scars set up the heart for dysfunction of the sinus node, the natural pacemaker of the heart, as well as other tachyarrhythmias (abnormal fast heart beats), such as atrial flutter and fibrillation.  The scarring can also lead to obstruction of inflow from the systemic or pulmonary veins.  Third, there is some evidence that those right-side left ventricles that require training do not hold up as well over the long haul, with decreased function seen.

For your son, without all of the data that I would need, I can’t say what his prognosis would be.  I can say that if he is asymptomatic and has only mild leakage of the tricuspid valve, you are not pushed to do anything urgently—this is assuming that his left-sided right ventricle is not significantly dilated.  By the way, the left ventricle is not pumping blood to the lungs under higher pressure; in fact, it is at the lower pressure seen on the right side, which is part of the problem for the ventricle as it becomes “detrained.”  As you may imagine, this is not a commonly performed procedure, only because l-TGA is not a common cardiac defect.  The Cleveland Clinic, one of the largest centers performing this procedure (prior to the retirement of their surgeon), reported on just 46 of these patients from a 9 year period.  Overall, this procedure has not been performed consistently well until the 1990’s, meaning that good long-term follow-up data is not abundant.

In regards to timing of the procedure, the Cleveland Clinic found that their best results occurred in patients under age 16 years, with significantly more perioperative complications occurring in older patients.  Therefore, it is not unreasonable to START thinking about this in your son, despite his age and lack of symptoms.  However, I would recommend that you discuss this thoroughly with your cardiologist as well as with the surgeon at the location that the procedure(s) will be performed to ascertain the best timing for this.  Make sure that you are familiar with their numbers and experience with this as well as their outcomes.
5 Comments
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Avatar_m_tn
Thanks so much for your response....my wife and I will continue to give this more thought and feel good knowing that this is not a decision we need to make tomorrow. In order to have a better idea on my son's prognosis, what is the data I would need to have (I probably already have it)?
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773637_tn?1327450515
Dear Jnani,

You pretty much need the information that you would want to ask for any surgery, actually.  How many has this surgeon and this institution performed?  What have been the short- and long-term outcomes?  What have been the complications?  At what age are they doing it?  What are their criteria for moving forward with a band and with a surgery?  Are they performing continuous quality improvement to assess their prior work and to improve outcomes for future patients?  You can also be bold and ask your cardiologist where else your son could be referred for higher volumes and/or better outcomes.
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Avatar_m_tn
Thanks very much for the info......I'm trying to search on my own what hospitals have conducted this procedure (double-switch) and what the outcomes were.....I'll also ask my son's caridologist. I would be interested in this info from the Cleveland Clinic, if you could point me in the right direction.
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Avatar_f_tn
Hi, my name is Sandra & I'm living in Sydney Australia with my husband and 2 kids (girl 9yrs and boy 5yrs...being the heart child). He had a "switch" and 3 x vsd's performed/fixed when he was 1 week old. It was only on his recent checkup (Dec 09) that I was told that his heart operates different to normal with his left doing the major work (I think it seems to be as you described above). I was also told he will have a murmur for the rest of his life. So far he is ok, but I was told that he may require surgery later in life to correct leaking of narrowing. This appears to be the 1st documentation I have found explaining my sons "switch" procedure correctly - all the rest explain the aorta & pulmonary arteries switched to correct place so heart now operates normal. So THANK YOU for putting my mind at rest that I did understand the cardiologist correctly and to understand how his heart is now wired. I am clarifying this with the cardiologist just to be 100% sure.
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Avatar_m_tn
A related discussion, valve repair or replacement for L tga was started.
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