The Wednesday Post (4/08/2010)

ResearchBlogging.orgSince I got back from the Microbiology conference in Sydney a little while ago I have been working my way through some DVD’s my wife picked up for me while I was away. Right now I’m finishing 8 seasons of Scrubs. I love Scrubs. I love that its stupid and goofy but I also love it because, for the most part, people don’t have a new disease that nobodies heard of every week. It portrays medicine as somewhat repetitive which is probably closer to what I’d expect, especially compared to ‘House’.

Any who, I was watching an episode recently which mentioned a disease I had heard about but assumed it was a bit of an in joke like Disease of the week syndrome. Takotsubo Cardiomyopathy a.k.a. Broken Heart Syndrome.

In the episode J.D. has a young and otherwise healthy patient that is going into heart failure. He turns away help from the one person that would actually be able to help (the grief counselor) and instead looks for a medical solution that doesn’t exist. Its only later that Dr. Cox, in an excellent parody of House, diagnoses Broken Heart Syndrome based on the presence of a wedding on her finger and the chart indicating she is single.

So how on Earth do you develop real heart failure due to depression? Well first we have to quickly do a course in cardiac physiology 101.

It has everything to do with how your heart works. Essentially, (and right now I predict that I shall be slaughtered in the comments but if you want to read a cardiac physiology blog, go find one :) ) electrical signals are generated in a patch of cells called the sinoatrial node (SA node) which is located in the right atrium. These cells set the pace of your hearts rhythm and are often referred to as the pacemaker cells. The electrical signal from the SA node spreads to both atria and they beat in unison. As the electrical signal spreads throughout the rest of the heart the signal is forced to pass through the atrioventricular node (AV node) which delays the electrical signal reaching the ventricle by approximately 0.1 sec. Thats why if you listen to your heart beat you hear 2 distinct sounds, the ‘thud-‘ of your atria followed by ‘-ump’ of your ventricles ‘thud-ump, thud-ump, thud-ump’.

Cardiac anatomy, somewhat simplified. <Modified from - http://commons.wikimedia.org/wiki/File:Heart_apical_4c_anatomy.jpg&gt;

Your SA node generates a steady rhythm but can be sped up or slowed down by the activity of your peripheral nervous system. Again, generally speaking, you can divide the peripheral nervous system into two halves, the ‘sympathetic¬† system’ that speeds things up and the ‘parasympathetic system’ that slows things down. If the sympathetic system starts to generate a signal onto the SA node your heart rate goes up (probably because you are running) but if the parasympathetic system is active instead your heart rate will slow (probably because you’re parked on the couch, watching Scrubs).

So heres where we start to work our way back to Broken Heart Syndrome. If your SA node starts to receive a lot more of one signal, say a sympathetic signal, you can generate an imbalance. the result of this is that the body, which has a standing policy of ‘use it or lose it’ starts to lose parasympathetic nerve endings in the heart which further exaggerates the sympathetic signal causing the loss of more parasympathetic nerve endings ….. its a vicious cycle. This imbalance can lead to the development of lesions in the heart tissue which in turn can result in altered heart activity, heart failure and death.

So how can an imbalance of nerve signaling develop? Well you can¬† inject the hearts of living mice with adrenaline (a major component of the sympathetic nervous system) and track changes in heart shape and activity (this was done but I cant find the reference for it, you’ll just have to take my word at this stage). Or you can suffer a major emotional trauma.

As I said higher up if your speeding things up you’re being stimulated by your sympathetic nervous system. The next time you’re really upset about something, check your pulse and breathing, they will be elevated above normal. It’s thought that if the sympathetic stimulation is intense enough the body might respond by withdrawing the parasympathetic nerves, over-stimulating the cardiac tissue with sympathetic signals, developing cardiac lesions and then you present to hospital with an acute myocardial infarction.

My question immediately was how do you treat someone who so depressed their heart is failing? It turns out that treatment is exactly what you think. Counseling and support. Over time the nerve endings will return and the heart rhythm will return to normal.

So you can die of a broken heart but love will bring you back from the brink. I think the human body can be quite poetic when it wants to be.

SHARE THIS!!!

Add to FacebookAdd to DiggAdd to Del.icio.usAdd to StumbleuponAdd to RedditAdd to BlinklistAdd to TwitterAdd to TechnoratiAdd to Yahoo BuzzAdd to Newsvine

References

Wittstein, I., Thiemann, D., Lima, J., Baughman, K., Schulman, S., Gerstenblith, G., Wu, K., Rade, J., Bivalacqua, T., & Champion, H. (2005). Neurohumoral Features of Myocardial Stunning Due to Sudden Emotional Stress New England Journal of Medicine, 352 (6), 539-548 DOI: 10.1056/NEJMoa043046
Nogueira, E., Ueti, O., & Vieira, W. (1995). The apical ventricular lesion in Chagas' heart disease Sao Paulo Medical Journal, 113 (2) DOI: 10.1590/S1516-31801995000200008

http://scienceblogs.com.br/brazillion/2010/07/broken_heart_syndrome_and.php

About these ads

14 Comments

Filed under James' Corner

14 responses to “The Wednesday Post (4/08/2010)

  1. Aha! I had no idea that adrenaline exposure could increase the sympathetic and decrease the parasympathetic connections at the SA node. It might be exactly why I’ve always been overclocked- my resting heartrate is rarely below 80 even if I’m really fit- when I was a kid, I was repeatedly rescued from acute asthma by IV adrenaline injections. At the time I couldn’t stand either the suffocation or the thumping heart and just wanted to run away. Those exposures probably “shorted out” the poor old node! What do you reckon?

  2. AnneR

    Can’t help saying this (and yes, I did actually READ the article, not just nitpick it), but….. man, you have to learn the difference between “your” and “you’re”. Badly.

    • Thanks for reading the article. I hope you enjoyed it, despite the bad grammar. A combination of insomnia, PhD and blog deadlines sometimes results in these slipping through. I think I’ve fixed most of them up now. If your [:)] able to find anymore just let me know.

  3. Pingback: Open Laboratory 2010 – submissions so far | A Blog Around The Clock

  4. Pingback: Open Laboratory 2010 – submissions so far | A Blog Around The Clock

  5. Pingback: Open Laboratory 2010 – submissions so far | A Blog Around The Clock

  6. Pingback: Open Laboratory 2010 – one month left to submit! | A Blog Around The Clock

  7. Pingback: Open Laboratory 2011 – three weeks to go! | A Blog Around The Clock

  8. Pingback: Open Laboratory 2010 – two weeks to go! | A Blog Around The Clock

  9. Pingback: Open Laboratory 2010 – only eight days till the deadline! | A Blog Around The Clock

  10. Pingback: Only three days to go – Open Laboratory final stretch for submissions! | A Blog Around The Clock

  11. Pingback: It’s getting hot – submissions for Open Laboratory 2011 are flying in by the dozens per hour… how about you? | A Blog Around The Clock

  12. Pingback: Open Laboratory 2010 – the final stretch! | A Blog Around The Clock

  13. Pingback: Open Laboratory 2010 – submissions now closed – see all the entries | A Blog Around The Clock

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s