Mounting Evidence Suggests Century-Old Hypothesis on How Major Arteries Function is Incorrect

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UPDATE Sept 19, 2017:
Emergence of a new paradigm in understanding the cardiovascular system: pulse synchronized contractions has been published in the Journal of Cardiovascular Pharmacology. 2017;6(5):220. doi: 10:4172/2329-6607.1000220.


It has long been observed that the aorta pulses in rhythm with the heartbeat. Prevailing wisdom is that the smooth muscle that forms the walls of major arteries, such as the aorta, are not able to actively contract quickly enough to keep up with the rhythm of the cardiac cycle. Therefore, it has traditionally been believed this rhythmic pulsing is merely a result of the elastic vessel walls being stretched by the blood flow with each heartbeat. 

In a commentary recently published in the Journal of Clinical & Experimental Cardiology, Allen Mangel, MD, PhD, and Executive Vice President of RTI-HS, examines the evidence that supports a different understanding of the behavior of the aorta during the cardiac cycle. “Proper understanding of the behavior of the arterial smooth muscle wall may lead to a new appreciation for the development of certain cardiovascular diseases, and, therefore, potentially inform novel approaches to the development of new cardiovascular therapies,” explains Dr. Mangel.

The theory that the aorta actively contracts in rhythm with the heart was first presented in a set of papers published in the 1950s and 60s by F. Heyman. Building on this work, several researchers, including Dr. Mangel, performed a series of experiments that demonstrate the presence of active contractions in the aorta--which have been termed pulse synchronized contractions (PSCs). Additionally, they designed a series of experiments specifically to rule out PSCs occurring as an artifact of the pulse wave or heartbeat. 

The results of these experiments showed the presence of PSCs in the absence of pulsatile blood flow or cardiac contractions; evidence also strongly supports that PSCs are initiated by the nervous system. Furthermore, the research was able to isolate their origin to the right atrium, possibly “designed” to allow excellent coordination between the heart and the PSC. Additional research demonstrated that it is possible for aortic smooth muscle to contract as rapidly as the heart rate.

This new understanding opens the door for additional research on the clinical significance of PSCs. Read the full commentary here.

See more vascular research by Dr. Mangel.


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