💛 Talking About the Heart: One Squish at a Time
🛪️ The Heart's Job
Imagine standing at a door in a room that's filling with water. Someone on the other side is trying to hold the door shut.
(But don't worry—you're not drowning in this story. Plot twist: you ARE the room. 🤯)
Your job (as The Heart) is to squish at least 50–70% (Ejection Fraction, or EF) of the water (blood) out of this room with every beat, pushing the door (your , or AoV) open about 60–80 times per minute (your heart rate, or HR) to keep the room from overfilling and dangerously pressurizing.
🔹 How You Manage the Squish
Preload: How much water (blood) is pushing from inside the room against the door.
Afterload: How strong the outside pressure is resisting you.
Contractility: How well you can squish the room (your strength).
If squishing fails:
Akinetic: No squish.
Dyskinetic: Weird, ineffective squish.
Hypokinetic: Weak, slow squish.
Afterload is how strong that other fellow (the pressure) on the other side of the door is. Preload is how much pressure or water is in the room pushing on the door from the inside. Contractility is your ability to squish the room. If you are not moving or can’t move, you are akinetic. If you are moving weird, or had a stroke, injury, etc… and can’t move one of your arms well, you (or your bad arm) are dyskinetic and may have issues squishing the water out well. If you are moving, but dragging ass and not moving as quick as your should, you are hypokinetic.
📊 Key Concepts
🛉 Afterload: The pressure in the aorta that the heart must push against to eject blood. Higher afterload = more work.
❌ Akinetic: Absence of movement. In general, you want the heart moving; areas that don't move may reflect old damage, scar tissue, or are on the way to turning into scar tissue.
🔘 Aortic Valve: The valve between the left ventricle and the aorta—the "door" you’re pushing open.
⏳ Cardiac Output: The total amount of blood ejected by the heart per minute.
Formula: Stroke Volume × Heart Rate
Normal at rest: About 5–6 liters/minute
Elite athletes during exercise: >35 liters/minute
(Cleveland Clinic link)
🤻 Contractility: The strength and ability of heart muscle cells to generate force.
🩸 Dyskinetic: Still moving but impaired; moving awkwardly and ineffectively.
⚖️ Ejection Fraction (EF): The percentage of blood ejected by the left ventricle with each beat.
Normal: around 60%.
⏱️ Heart Rate: The number of heartbeats per minute (BPM).
Important Detail:
Heart Rate = beats of the heart.
Pulse = pressure waves you feel in arteries.
In some conditions (PVCs, atrial fibrillation), not every heartbeat produces a palpable pulse. - Expressed in beats per minute or BPM; it’s how many cardiac contractions happen over the course of one minute.
Sometimes referred to as pulse, these are, technically, be different. Maybe this gets over specific to a “well, acthually….” degree, but there is probably a situation where it makes a difference to clarify exactly what you are talking about; heart beats or pressure waves received at distal points of the body. HR measures the beats of the heart, pulse measures the pulse waves in the arteries and these can differ if there is a low pressure pulse wave that does not reach the pulse point being palpated, like will happen with PVC’s or atrial fib beats that don’t carry as much pressure and won’t be felt at the wrist or fingertips.
💥 Hypokinesis: Diminished movement; the heart squishes weakly or sluggishly.
📀 Preload: The pressure inside the left ventricle after it fills and relaxes.
Topped off by atrial contraction.
Loss of atrial kick (e.g., in atrial fibrillation) reduces preload.- amount of pressure in the Left ventricle after relaxing, filling up, then (ideally; this can reduce w/ AF or A-flutter) getting topped off by the atria.
🧰 Pulse: The pressure wave created by heart contractions, felt at points like the wrist or neck.
Expressed per minute.
May differ from heart rate if some beats are weak; this is the count of pressure wave coming from the heart and reaching the pulse point. See the longwinded thought under Heart Rate (Pulse and Heart Rate may not be the same).
💛 The Heart: Identified as one of the organs, it lives rent-free in your chest and is suspected of having an important role in biological life (doing the hard work of keeping you alive).
Final verdict: Critically important, ceaselessly hardworking, and 100% awesome.
📘 Final Notes
🎭 A visual diagram could enhance the "room filling/door pushing" analogy.
📊 Expansion idea: Discuss preload with the Frank-Starling Law.
🏋️ Optional: Add clinical examples (e.g., afterload increases in hypertension, preload drops in dehydration).
