# Changing the PV Loop

1 program

10 videos

Once you’ve learned about the PV loop, a natural question arises - Does it ever change shape? It turns out that there are precisely three things that can change the shape of the loop: 1. Preload, 2. Afterload, and 3. Contractility. That’s it! The tricky part comes when you try to change one and you realize that the body begins to change the other two as well as a natural consequence. In order to simplify, you’ll find that PV loops are sometimes even described as PV boxes. You’ll get to learn about PV loops, PV boxes, and even play around with them yourself in this tutorial!

### What is preload?

VIDEO
13:33 minutes

Some say Preload = End-Diastolic Pressure, others say Preload = End-Diastolic Volume, so which one is it? Watch and find out! Rishi is a pediatric infectious disease physician and works at Khan Academy.

### What is afterload?

VIDEO
10:28 minutes

Rishi is a pediatric infectious disease physician and works at Khan Academy.

### Increasing the heart's force of contraction

VIDEO
14:30 minutes

Find out exactly how stretch increases force of contraction in end-diastole, whereas more calcium increased force of contraction in end-systole. Rishi is a pediatric infectious disease physician and works at Khan Academy.

### Reimagine the pressure volume relationship

VIDEO
13:38 minutes

Understand what is happening at the cellular level to cause two identical left ventricular volumes to have such different pressures! Rishi is a pediatric infectious disease physician and works at Khan Academy.

### What is contractility?

VIDEO
13:45 minutes

Contractility tells us how many myosin heads are working at the end of systole; a number that goes up or down with the level of sympathetic nerve stimulation. Rishi is a pediatric infectious disease physician and works at Khan Academy.

### Getting Ea (arterial elastance) from the PV loop

VIDEO
11:21 minutes

Find out how to use the PV loop to draw the Ea (Arterial Elastance) line, and what it represents. Rishi is a pediatric infectious disease physician and works at Khan Academy.

### Arterial elastance (Ea) and afterload

VIDEO
9:33 minutes

First, learn the difference between arterial elastance (Ea) and afterload. Then, understand how Ea is affected by changes in afterload, and in turn, how the PV loop can shift. Rishi is a pediatric infectious disease physician and works at ...

### Arterial elastance (Ea) and preload

VIDEO
7:43 minutes

Understand how Ea is affected by changes in preload, and in turn, how the PV loop can shift. Rishi is a pediatric infectious disease physician and works at Khan Academy.

### Stroke work in PV loops and boxes

VIDEO
6:53 minutes

Watch how PV loops can be "morphed" into PV boxes to make drawing them and thinking about them much simpler. Rishi is a pediatric infectious disease physician and works at Khan Academy.

### Contractility, Ea, and preload effects on PV boxes

VIDEO
13:11 minutes

See how contractility, Ea (arterial elastance), and preload each have an effect on PV Boxes. Rishi is a pediatric infectious disease physician and works at Khan Academy.

### Pressure-Volume Boxes

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