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BP & PVC's
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BP & PVC's

If one has frequent PVC's, could it temporarily give an erroneously high systolic blood pressure reading if it occurs just as the measurement on the sphymomanometer drops near the expected systolic value, i.e. could the PVC, since it's stronger in voltage amplitude, sound through the stethoscope like the first expected sound of the systole as the health provider listens for it, and then be mistakenly interpreted as the upper reading of the blood pressure measurement? I ask this question after many years of monitoring my own B/P (and others) as a health professional.  
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230125_tn?1193369457
That is an interesting question.  The answer is stressed in the first year of medical school as a principle called Starlings Law or Frank Starlings Law or the Starling effect.

http://en.wikipedia.org/wiki/Frank-Starling_law_of_the_heart

If the PVC comes just a the right time, the blood pressure may measure high but if it is measured a second or so before that time, the measurement will be low.  The force of ventricular contraction is depend on filling -- the more blood filling the heart, the more forceful the subsequent beat.  When the heart fills, the sarcomeres (basic unit of muscle tissue in the heart) stretch and up to a certain point, more stretch means a more forceful contraction.

The PVC is a premature beat so there is less time for the heart to fill and therefore generates a less forceful contraction.  During this time blood pressure measurements may be lower than normal and it is also during this time that some people feel a little light headed.  The subsequent beat after the PVC has more time to fill and therefore generates a more forceful contraction -- this is usually the beat that people feel and occassionally describe as painful.  Blood pressure measured at this point will be higher than normal in everyone except those with hypertrophic cardiomyopathy -- they have a paradoxical drop in blood pressure after a PVC.

The same is true for atrial fibrillation.  There is constantly irregular filling intervals for each beat.  This can lead to variable systolic pressures.

PLEASE don't use this as a reason to not treat hypertension.

I hope this answers your questions.  I provided the link to wikipedia so you can read about this in another article.  Feel free to do more google searches on this, there is a lot out there on the Frank Starling Effect.

Thanks for posting.
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