Thursday, February 28, 2008

Will Ferrell is Good For Your Arteries.

Well, assuming you find Will to be funny then watching his movies just might improve the functional responses of your arteries. You might have heard "laughter is the best medicine" or maybe even that laughing is good for your heart. But is there any truth to this? The journal Heart (formerly the British Heart Journal) published a scientific letter titled "Impact of cinematic viewing on endothelial function" in 2006 that just might have the answer (link to abstract). Heart 2006;92:261–262

These authors studied the blood flow responses in the arteries of the arm in subjects before and after they watched movies. They compared the vascular responses of individuals that watched movies evoking mental stress (e.g., Saving Private Ryan) versus individuals watching movies evoking laughter (e.g., There's Something About Mary).

They found movies that made you laugh improved endothelial-dependent blood vessel dilation (see the figure below)... this is a fancy way of saying that the arteries and arterioles dilated more in response to a stimulus and thus improved blood flow. The laughter group had improved arterial vasoldilation compared to baseline while the mental stress group actually had impaired vasodilation compared to baseline. They tested this using reactive hyperemia which A&P students remember from lab. Reactive hyperemia is a transient increase in blood flow to an organ or tissues after a period of ischemia or arterial occlusion. Basically, the authors occluded blood flow to the arm for five minutes (ouch) and then released the occlusion. They used ultrasound imaging to capture the diameter changes in the brachial artery during the experiments to assess the functional responses during hyperemia. In class, we merely looked at the redness in the skin to assess the extent of hyperemia (see our class images). In the movie experiments, during hyperemia, brachial arteries dilated to a greater extent in the arms of laughter viewers. By the way, the reason it is called "endothelial-dependent" is because the endothelial cells are important in generating the signals that contribute to the blood flow changes. The mechanisms explaining the findings of this study are unknown but the authors did speculate that nitric oxide (NO) signaling could be involved. You might remember that NO produced by cells, like endothelial cells, can cause smooth muscle relaxation and thus improve blood flow.

Conclusion: go see funny movies and not stressful or scary ones! Superbad, not super scary... after all, it is good for the function of your arteries.

Heart 2006;92:261–262


Tuesday, February 19, 2008

Eat your heart out...

You don't often get to see an anatomically correct-extra-credit-chocolate-human heart cake... but alas you will today. I am not easily impressed but this cake looked great and the myocardium has never tasted better! Actually, I think I see the left circumflex artery too. Enjoy. [Link to Full Size Cake Heart]

cake heart diagram labeled

Courtesy of Jaclyn.



Thursday, February 14, 2008

♥ ♥ What's in a Kiss? Science of Kissing ♥ ♥

With Valentine's Day upon us, it is not surprising to see web articles about kissing... how to kiss, how not to kiss, best movie kisses, best lips (btw, who is the owner of the famous lips in the pic over there--->). What about the science of kissing? Why do we kiss? Is there a biological basis of kissing? A recent article at Scientific American has all the answers... well, a few answers and it is all free and available if you follow this link. You should check it out but here are some tidbits that I found particularly interesting:
  • Kissing may have evolved from primate mothers’ practice of chewing food for their young and then feeding them mouth-to-mouth.
  • Osculation is the fancy, scientific term for kissing... as in "I don't osculate on the first date."
  • Up to 10% of the human population does not kiss, that is over 650 million people... I assume that is a cultural thing?
  • Some scientists theorize that kissing is crucial to the evolutionary process of mate selection. Bad kisser = bad genes? Sort of a litmus test for mates.
  • The process of kissing utilizes five of the 12 cranial nerves to transmit signals to and from those lips... can you name them? See the end of this blog post. I am trying to remember them all.
An interesting issue that caught my attention is the idea of the kiss as an important factor in mate selection (i.e., the litmus test). Does a kiss provide more information about compatibility then we consciously realize? Everybody says how important the first kiss is, right? Perhaps a couple's "kissing compatibility" signals some sort of primal or fundamental fit between potential mates.... or... maybe it is just kissing. Who knows.

One thing not discussed in the article is the origin of lips... there must be some anthropologist studying this stuff... lip morphology? Was a certain type of lip selected for during evolution through mate selection? We might assume nowadays that bright, full lips were probably attractive to mates but is that really true of our ancestors? Is there any biological significance or advantage of full versus thin lips other than mate selection? Have lips changed dramatically since our more ancient, primitive ancestors? Maybe ask your physical anthropology professor. PS- Everything you wanted to know about Lip Anatomy and more courtesy of two different articles at eMedicine. [Link1] and [Link2]

Answer for 5 Cranial nerves used in kissing: Trigeminal V (sensory touch for tongue and lips); Facial VII (muscles to move lips); Hypoglossal XII (muscle to move tongue); Facial VII and Glossopharyngeal IX (taste sensation from the tongue); hmmm they say 5 of the 12 so perhaps they include Olfactory I (smelling while you kiss).


Monday, February 11, 2008

Panthers, Pucks, Skates, Carotid Arteries... Huh?

Florida Panthers forward Richard Zednik survived a potentially deadly gash to the neck that partially severed his right common carotid artery (Associated Press link). During the hockey action his teammate fell directly in front of him and the teammate's skate came up to neck level slicing directly into Zednik's right neck. In video of the incident, blood can be seen spraying the ice below Zednik as he falls grasping his neck. He quickly got up and skated to the bench, holding his neck. He was rapidly helped from the ice and later underwent emergency surgery to repair his right carotid artery which doctors indicated was hanging on by only a small thread of tissue. His right external and internal jugular veins were not damaged. As of writing, he was in stable condition in the hospital. He seems very lucky! Doctors say he lost approximately 5 units of blood... that is a bit more than 2 liters. Imagine a 2-liter bottle's worth of bood spilling out of your body. During the surgical repair, the right carotid was clamped for several minutes which would seemingly reduce blood flow to the brain. His doctors said he did not seem to have any brain injury or brain damage due to the interrupted carotid blood supply. Of course A&P students know the left common carotid and vertebral arteries also carry blood to the brain.

There is video of the incident on YouTube if you want to see it for yourself (YouTube link).

A great video for physiology / anatomy students is the medical press conference with the Buffalo Sabres team physician and the emergency surgeons that helped save Zednik... linked here (Buffalo General Hospital). Watch this as it has a terrific discussion of the anatomy of Zednik's injury. Interestingly, the team physician mentions that this injury was not like a previous NHL injury to the neck of goalie Clint Malarchuk which severed his jugular vein. The jugular is a low pressure vein carrying blood away from the head while the carotid is a high pressure artery carrying blood to the head. Large artery injuries are always very dangerous due to the threat of rapid blood loss which could severely reduce blood pressure, causing loss of consciousness and eventually death. As the angiogram below shows, the carotid arteries are large and are located close to the aortic arch and the heart itself... thus a severed carotid artery is serious business and Zednik is lucky to be alive.


Saturday, February 9, 2008

This is not your parents' CPR: continuous-chest–compression CPR

CPR (cardiopulmonary resuscitation) without mouth-to-mouth rescue breathing? It is called continuous chest compression CPR or compression only CPR and requires no rescue breaths. Several studies suggest that continuous chest compression CPR for adults that collapse suddenly presumably due to cardiac arrest is just as good as standard CPR or possibly even better. Okay, perhaps you are thinking... no way! What about 15:2 or the newer 30:2 compressions to breaths I learned in CPR class?

Researchers from Seattle, Tucson, and Japan have shown that bystander CPR is equally effective or better when performed with chest compressions alone compared to standard CPR with alternating compressions and rescue breaths. Why would this be? Isn't the point of CPR to breath for the person and to circulate their blood by compressing the chest? Right... but the blood is well oxygenated when somebody suddenly collapses from cardiac arrest (i.e., heart stops pumping). Thus, rescue breaths are not really necessary to get oxygen into the blood... rather chest compressions are most important to get needed blood flowing to the brain and heart's myocardium. In fact, delaying the compressions in order to perform breathing might actually reduce the effectiveness of CPR. The technical details are reviewed in Circulation by Dr. Gordon Ewy of the University of Arizona Sarver Heart Center. It seems the oxygenated blood in the body can support the heart and brain for several minutes as long as it is circulated adequately via chest compressions.

Some communities are already teaching continuous chest compression CPR... some have called this new CPR "Call and Pump" referring to the need to call 911 and then begin 100 chest compressions per minute until "the patient or paramedics tell you to stop" or until you can't continue. A very short and detailed tutorial on continuous chest compression CPR is published in Circulation. Go read it! This type of CPR is not recommended in children or when respiratory arrest is suspected such as drowning, drug/alcohol overdose, choking, severe asthma or carbon monoxide poisoning... in these cases CPR with mouth-to-mouth breathing is needed to help oxygenate the blood since the primary problem is not the heart but a lack of oxygen (i.e., suffocation) that eventually leads to cardiac arrest.

A study published in Nov. 2007 (Circulation) used a swine (pig) model of out-of-hospital cardiac arrest with bystander CPR to compare continuous chest compression (CCC) CPR with standard 30:2 compression to breaths CPR. Animals in cardiac arrest for varying amounts of time (3-6 minutes) due to ventricular fibrillation then underwent either CCC or Standard CPR. After 12 total minutes of fibrillation (cardiac arrest), defibrillation was performed using advanced cardiac life support standard guidelines. In essence, this study simulated a collapse, followed by some delay to the start of bystander CPR followed by later arrival of medics that initiated defibrillation. Then 24-hr after the resuscitation, survival and neurological state were evaluated. Neurologically normal survival at 24 hours after resuscitation was observed in 23 of 33 (70%) of the animals in the continuous chest compression group compared with only 13 of 31 (42%) in the standard 30:2 CPR group. Thus, CCC CPR improved survival with normal neurological function compared with standard CPR. Of course, this is an animal study and not humans. Nevertheless, the results are compelling and suggest that mouth-to-mouth might not be needed and could even be detrimental in the case of sudden cardiac arrest. Why? The idea is that the continuous compressions increase cerebral and coronary blood flow and thus improve survival. Interruptions in chest compressions required for rescue breathing reduce perfusion to the heart and brain which could explain the reduced survival and neurological outcomes with 30:2 CPR in this animal study.

The key potential benefit of compression only CPR is the idea that more bystanders would initiate and perform CPR if it is simple to remember and it does not require mouth-to-mouth contact.

This recent research might be changing the way you learn bystander CPR in the near future... well probably not until 2010 when the American Heart Association will review and revise CPR guidelines. But CPR can be easy and the key is to do it!

Finally, CPR helps save lives but ultimately defibrillation (shocking) of the heart is needed for the patient to recover from cardiac arrest. The faster this happens the better. Automated external defibrillators (AEDs) are becoming common place in gyms, malls, and airplanes. The faster bystanders or medics can shock the heart back into rhythm then the better the survival rate for the subject. Interestingly, after about 5 minutes of cardiac arrest, performing compressions immediately before and after the defibrillator shock appears to help survival rates. IN 1999 a study by the University of Washington and Seattle Fire Dept showed improved survival if medics performed 90 seconds of CPR immediately before automated external defibrillation was attempted (JAMA link). Basically, if the subject had been collapsed for 4-5 minutes or longer then CPR (with the goal of 150 compressions in 90 seconds) prior to any attempt to shock the heart actually improved survival. In a Norwegian study, 3 minutes of standard CPR was performed by arriving emergency personnel prior to attempts to shock the heart compared with immediate attempts to shock the heart (JAMA link). Overall, no difference in survival rates was observed until researchers examined the survival of subjects with ambulance arrival times greater than 5 minutes after collapse. In these subjects, 3 minutes of CPR prior to defibrillation significantly improved survival to hospital discharge (22% in the CPR first group versus 4% in the immediate defibrillation group). See figure below.