top of page
Search
  • paspacjourney
    • Aug 22, 2022
    • 11 min read

BONUS-BONUS 1: CARDIAC MURMUR STUDY TIPS

Learn how to remember cardiac murmurs

- by reviewing the transcript and resources below for our bonus podcast episode so you never have to memorize the nuances again.

Welcome to PASPAC Podcast, your audio passport from Physician Assistant Student to Certified – And Beyond – with your host, Rebecca Harrell, MPA, PA-C


Today our bonus-bonus destination is an in-depth review of cardiac valvular murmurs, so you never have to memorize them again

So sit back, relax, and lets get to it.

Hey everyone, Its Becca

I’m calling this a bonus-bonus episode because I really chose to do this on the fly, unlike my other bonus episodes, which I already have planned out. My original intention was to write a blog post on this topic, but I realized that the way to truly explain them has a lot to do with intonation and reviewing what certain things truly mean - instead of simply writing and having y'all read a book – because after I finished what was going to be the blog post – it really was essentially going to be a book.


Don’t worry, I’ll still post what I was going to as the transcript to this episode so you will have everything, we cover at your fingertips over on the website at www.paspacpodcast.com



One of the most frustrating concepts to learn in PA school is all of the nuances between the various cardiac murmurs. I felt like no matter how many times I studied them and got them down, by the time the next exam came around – I forgot them all over again and had to start from scratch. One day, I got so fed up with trying to memorize them for the one millionth time, that I decided to just try and actually truly take the time to connect the dots and understand the actual pathophysiological aspects surrounding each of those minute details.

If you’re looking to do the same so you never have to memorize them again, you’ve come to the right place.

Instead of looking at the whole picture at once and jump into each valvular disorder- let’s break it down to the basics and build it back up.


First, Refamiliarize yourself with the vocab and think about what it is actually doing to blood flow (and why)


1. Murmur: Sound caused by turbulent blood flow

  • Stenosis: Difficulty opening – think of putting your thumb partially over a hose and turning it on – turbulent blood flow pushes forward

  • Regurgitation: Difficulty closing– think of turning off the hose and all of the water still inside the hose falls backward into the tubing instead of through the spout – turbulent blood flow falls backward

2. Systolic vs Diastolic Murmur depends on which valves should be open vs. closed

  • Quick mnemonic: “You must PASS to get PAID”

    • Pulmonic/aortic stenosis systole, Pulmonic/Aortic insufficiency Diastole

    • Mitral/tricuspid opposite

  • Systole = Closure of Mitral and Tricuspid valves (S1) and opening of the Aortic and Pulmonic valves

    • Therefore:

      • Difficulties closing (regurgitation) of the mitral and tricuspid valves leads to a murmur during systole

      • Difficulties opening (stenosis) of the Aortic and Pulmonic Valves will also lead to a murmur during systole

  • Diastole = Closure of the Aortic and Pulmonic Valves (S2) and opening of the Mitral and Tricuspid Valves

    • Therefore:

      • Difficulties closing (regurgitation) of the aortic and pulmonic valves result in murmur during diastole

      • Difficulties opening (stenosis) of the mitral and tricuspid valves will also lead to a murmur during diastole

3. Locations and Radiation: Which valve is messed up and where does that make the blood travel (As a reminder, think of stenosis shooting the blood forward like a pressure hose and regurgitation allowing the blood to fall backwards)

  • Aortic: 2nd ICS, Upper Right Sternal Border (High Yield)

    • Stenosis – turbulent blood flow forces its way forward into the carotids

    • Regurgitation – regurgitant blood will “fall backwards”, radiating to the apex

  • Pulmonic: 2nd ICS Upper Left Sternal Border

    • Stenosis Radiates to left clavicle/shoulder and usually has a palpable thrill (remember, the right ventricle is the most anterior chamber, leading to easier ability to feel the turbulent stenotic flow “shaking” the chest wall)

    • Regurgitation - Non-radiating, but back up can lead to hepatic congestion as blood is falling backward from right side of heart into body

  • Tricuspid: 5th ICS, Lower Left Sternal Border (lower yield)

    • Stenosis: similar to mitral with rumbling sound, but around xiphoid Regurgitation: Non-radiating, but can lead to a pulmonic ejection click if secondary to back up from lungs in pulmonary hypertension

  • Mitral: 5th ICS, Mid-Clavicular Line (High Yield)

    • Stenosis: Apex with rumbling against the apex as it pushes through the valve

    • Regurgitation: Apex with regurgitation falling backward toward the axilla

4. Dynamic Maneuvers

  • Preload: Stretching of the ventricle sarcomeres prior to contraction

    • What is the simplest way to think about what increases stretch? More Blood.

      • More Blood → More Stretch → Increased Contractility → Increased Stroke Volume (to an extent, lets not get started on the Frank-Starling stuff)

      • What allows more blood to get into your ventricles? Many things, but let’s focus on the high yield.

        • Slower heart rate (more time to fill)

        • Increased Ventricle Compliance (allows greater expansion)

        • Increased central venous pressure by either decreased venous compliance (aka venous constriction) or increase in total thoracic blood volume by general increase in total blood volume or increased venous return, more on that later.

      • What's the simplest way to think about what decreases stretch? Less Blood.

        • Same principle applies as above, but essentially opposite.

        • What sorts of things keep blood from getting into your heart?

          • Faster heart rate (less time to fill) - This also applies to quivering/ or impaired atrial contraction in atrial arrhythmias

          • Decreased ventricle compliance (less expansion)

          • Decreased central venous pressure from less total blood volume (hemorrhage), less ventricular filling (mitral/tricuspid stenosis), or decreased venous return

    • Increase Preload by doing things that help more blood get into your heart

      • Example: Leg Raises and Squatting

        • When blood shifts out from your lower extremities, either from gravity with leg raises, or from force with squatting, you’ll increase preload

    • Decrease Preload by essentially doing things that increase the distance or make it more difficult for the blood to actually get to your heart

      • Example: Valsalva and Standing

        • Valsalva maneuver, or bearing down, will do a couple things BUT most HY to remember for murmurs is how it acts to decrease preload

          • Increase in intrathoracic pressure will decrease venous return to the heart.

        • Standing is essentially doing the same thing, but with gravity

  • Afterload – amount of force is needed to push blood out of the heart during contraction

    • Think of afterload as something sitting or pressing on the aortic valve (like Hodor in GoT holding that door shut) – requiring the heart to use a lot more force to push that door open if the afterload is elevated (which is essentially telling your LV to start lifting weights – i.e., resultant hypertrophy, but I digress)

    • Increase Afterload by making it harder to push the "aortic valve door" open to get blood from your heart into your system

      • Example: Hand Grip

        • When you initiate a hand grip, you’re making the muscles in your upper extremities squeeze your vessels, leading to narrower, higher pressure, pathways.

        • The increased force you’re creating essentially acts like Hodor pressing against your aortic valve door and making the blood have a harder time getting out of your heart into your body.

        • When something is essentially sitting on that door, the murmur in stenosis (trying to push through the door) will decrease because no turbulent blood flow is getting through. No turbulent blood pushing through the stenotic valve = Less sound.

        • By contrast, it tends it tends to increase the sound of a regurgitation because the “force” from the afterload “pushes the flow backward” even harder, through the faulty regurgitant valves

    • Decrease Afterload by taking the “load” off of the aortic valve, allowing blood to flow through it easier and smoother

      • Example: Amyl Nitrate

        • This decreases peripheral vascular resistance leading to an easier time getting blood out of the heart into the body and also allows for smoother flow getting blood from the body into the heart (secondary to increase in venous return)

  • Venous Return with Inspiration and Expiration

    • Quick mnemonic: RILE (right inspiration, left expiration) - as in, right sided heart murmurs increase with inspiration and left sided heart murmurs increase with expiration

      • Inspiration

        • In simple terms, when you pull air into your lungs, you’re doing so by decreasing your intrathoracic pressure and allowing the lungs to expand. As a result, the decreased intrathoracic pressure allows your systemic venous blood flow to pass through more readily into your heart.

        • Another way I like to picture this (while likely not truly scientifically sound, but helps for visualization purposes) is to picture the lungs expanding and pressing on your vena cava to shoot the blood into the right side of the heart

        • Due to increased blood in RA, pulmonary blood volume will increase, which will result in decrease flow to left atrium (because it is now being used to filling up those expanded lungs) that later increases again with expiration

        • What does this mean for a murmur?

          • Right sided murmurs will typically be louder during inspiration due to the increase in volume of turbulent blood flow passing through the faulty valve

          • By contrast, Left sided murmurs will typically be quieter during inspiration due to the decrease in volume returning into the LA at that moment.

    • Expiration

      • Essentially, this leads to two things:

        • Air is pushed out of your lungs by an increase in intrathoracic pressure (vs. decreased like in inspiration). The increased pressure acts like a roadblock for the vena cava, decreasing the blood flow into the right side of your heart.

        • Constriction of the pulmonary vessels as the lungs deflate forces the blood into the left side of the heart.

        • What does this mean for a murmur

          • Left sided murmurs will typically be louder during expiration due to increase in volume of turbulent blood flow passing through the faulty valve

          • Alternatively, Right sided murmurs will be quieter

  • The Weirdos

    • Though this is really about stenosis/regurgitant valvular disorders, I would be remiss to not include a discussion of the weirdo murmurs that trip us up when thinking about what typically leads to an increase and decrease in murmur intensity

    • Mitral Valve Prolapse and Hypertrophic CMO

      • While most murmurs decrease intense with intensity during Valsalva (aka decreased preload) and increase with intensity with squatting (aka increased preload), these two dare to be different.

      • What turns the volume up – Standing/ Valsalva (Decreased Preload)

        • HCMO: Murmur is due to the thickened/asymmetrical septum in the hypertrophic muscle, if the septum isn’t pushed flat enough from a higher volume of blood, the turbulence over that asymmetric septum is greater

        • Because blood flows over the septum during systole, remember this as a systolic murmur even though HCMO is a diastolic dysfunction with S4 heart sound (hypertrophy leads to decreased area for blood to fill/increased force to stretch against a non-compliant ventricle)

        • Therefore, decrease in preload (Valsalva) makes the murmur louder because there isn't enough volume to force the septum flat

      • MVP: A similar concept leads to a more audible click earlier in systole

        • Think about the “midsystolic ejection click” as the force of systole hitting the mitral valve like wind would sound as it slaps against the underside of an umbrella/ gazebo cover. This visualization can also give you an idea of how it eventually can lead to regurgitation. Less wind (preload) will snap against that umbrella like a quick gust, leading to a more audible click occurring earlier in systole.

        • This may be harder for you to visualize than HCMO, so just remember HCMO and MVP follow the same maneuver rules and you should be good to go.

      • What turns the volume down and why – Squatting / Leg Raise

        • Same concept as above, but increase blood flow flattens the septum leading to decreased murmur of HCMO

        • I also like to imaging the increase in blood volume buffering the "click" of MVP leading to a decreased intensity and delay to be audible later in systole due to a larger force of wind steadily pushing on the MV, as opposed to that sharp gust with decreased preload. (Don't forget once MVP shifts to MR, it goes back to what you would expect with increased afterload intensifying sound and decreased preload softening sound)


OKAY, based on the above – lets put it all together


LEFT SIDED – murmurs decrease with inspiration, increase with expiration (RILE)

  • Aortic Valve (Opened in Systole, Closed in Diastole)

    • Aortic Stenosis → problem opening → systolic murmur

      • Acts like a finger over the hose → harsh systolic ejection murmur

      • Increased force → radiation up to the carotids

      • Putting more blood into the heart (aka ↑ preload with leg raise/squat) → increased volume of blood pushing past a stenotic valve → increase in murmur’s intensity

        • Alternatively, less blood into the heart (aka Valsalva/standing leading to ↓ preload) leads to decrease in intensity from less turbulent flow

      • Sitting on the valve (aka handgrip leading to ↑ afterload) → less turbulent blood flow able to push through → decrease in murmur’s intensity

        • Alternatively, when you stop pressing against the aortic valve’s “door” (aka amyl nitrate, ↓ afterload) the blood flow that goes over the stenotic valve increases → increase in murmurs intensity

    • Aortic Regurgitation → problem closing → diastolic murmur

      • Blood flows backward → radiating toward apex

      • As usual with venous return/preload (except with our weirdos)

        • Increased preload increases turbulent flow through regurgitant valve leading to increase in murmur intensity

        • Decreased preload leads to decreased blood flow through the regurgitant valve, which decreases the murmur's intensity

      • When force is applied against a door that already has a problem closing (aka handgrip, ↑ afterload) more blood flows backward → increased murmur intensity

        • Alternatively, taking the force off the door (↓ afterload) allows for easier flow of moving forward through the regurgitant valve (aka less blood falling backward) → decreased murmur intensity

  • Mitral Valve (Closed in Systole, Opened in Diastole)

    • Similar concepts as aortic valve in regard to dynamic maneuver’s effect on stenosis/regurgitant murmurs

    • Mitral Valve Stenosis → problem opening → diastolic murmur

      • Turbulent jet through stenotic valve → rumbling against the apex

      • Similar to the others, increased preload leads to increased sound and decreased preload leads to decreased sound; however, afterload has a negligible effect on MS

    • Mitral Valve Regurgitation → problem closing → systolic murmur

      • Blood flows backward through the high pressure LV into lower pressure LA → holosystolic murmur that radiates back toward the axilla

      • Similar to aortic regurgitation, decreased afterload decreases blood flow backward and therefore decreases the intensity of the murmur; whereas increased afterload pushes the blood backward more forcibly and increases the intensity of the murmur

      • Also similar to AR, decreased preload leads to decreased blood to flow backward, thus the sound decreases and with increased preload, more blood can flow back leading to louder intensity

RIGHT SIDED - murmurs increase with inspiration, decrease with expiration (RILE)

  • Pulmonic Valve (Open in Systole, Closed in Diastole)

    • Pulmonic Stenosis → problem opening → systolic murmur

      • Stenosis itself will lead to increased afterload → turbulent jet will be harsh and loud that radiates toward the left clavicle/shoulder and +/- thrill secondary to anterior LV vibrating against chest wall

      • Maneuvers affecting right sided murmurs are primarily associated with things that affect systemic venous return such as inspiration (louder) and exhalation (softer)

    • Pulmonic Regurgitation → problem closing → diastolic murmur

      • Because this is usually caused by increased pulmonary pressure (aka pulmonary hypertension), the blood flow backwards will be high pitched as the increased afterload forces the blood backwards

      • This can sound similar to aortic regurgitation, however in pulmonic regurgitation, unlike aortic regurgitation, inspiration will increase the murmurs intensity (aka make it louder)

  • Tricuspid Valve (Open in Diastole, Closed in Systole)

    • Tricuspid Stenosis → problem opening → diastolic murmur

      • Turbulent flow forward through a stenotic valve, as with mitral stenosis, leads to a diastolic rumbling that will increase with inspiration

      • Typically, will present with an opening snap (similar to mitral stenosis) as the “crusty” valve snaps open

    • Tricuspid Regurgitation → problem closing → systolic murmur

      • As with pulmonic regurgitation, you’ll hear a high pitched blowing murmur from the force of blood backwards from higher pressure pulmonary hypertension into lower pressure RA which will also increase with inspiration

      • Because this occurs during systole, you’ll hear a holosystolic murmur over the LLSB and radiating toward the xiphoid

      • As with pulmonic disorders, Look for signs of right sided heart failure with this as blood flows backwards, congesting the body, leading to JVD, peripheral edema, and hepatic congestion.

Don't forget to look at other factors in your stem that might help you distinguish between your murmurs

  • For example, the etiology of a left sided murmur may lead to signs of pulmonary congestion (L for Left = L for Lungs)

  • Alternatively, the etiology of a right sided murmur, may lead to signs of systemic congestion (R for Right = R for the Rest)

This all may seem a little confusing at first so please listen to the episode as many times you need and utilize the transcript for your notes to help you nail this down. After you have your "aha moment" you'll never have to memorize them again.


If you found this helpful, please like, comment, share, review - do all the things to help bring the podcast and Instagram (@paspac_passport) to others who may find it helpful to them as well.


Until Next Time,

Safe Travels


DOWNLOAD TRANSCRIPT BELOW


RESOURCES






Comments

bottom of page