In today’s micro lecture, Australian Paramedical College Hon. Snr. Lecturer Sam Willis discusses Left Ventricular Failure (LVF).
In this lecture, we’re going to talk about left ventricular failure. So, as you can imagine, it’s a pretty serious situation when the left ventricle is failing to pump blood, and that’s because the left ventricle is pushing blood at extreme forces against a lot of resistance all the way around the body, all the way up to the brain, all the way down to the peripherals, including the hands and feet, and the force must be so great that it’s able to return that blood back up through the system and back into the right side of the heart. So, that’s what we’re going to talk about today: left ventricular failure.
We’re going to start with a case study to help to make this a little bit more interesting. So, the purpose of the session is to go back over the basics of the blood flow through the heart, so that you can remind yourself of the different chambers in the heart, we’re going to look at the importance of the left ventricular and recognize how the signs and symptoms of LVF, left ventricular failure, relate to the failure of the left ventricle. But first, let’s just start with a case study.
Now, put yourself in this position. You are the paramedics walking into this situation. You’re called to a private address to reports of a 52-year old female acting strangely and having difficulty in breathing. On arrival, the daughter greets you and tells you that her mother has a history of heart failure and has not been taking her medications. The mother appears extremely short of breath, is using accessory muscles to breathe, and is acutely confused. So, let’s talk a little bit about this case study.
So, first of all, it’s a private address, meaning there’s no prying public eyes on the outside. It doesn’t mean there’s not on the inside, but it looks like, on this occasion, it’s just the daughter that’s on the scene because you’ve always gotta consider your history, you’ve gotta consider your safety, you’ve gotta consider your access and egress. Those things are always in the back of your mind as a paramedic. The call comes in as female acting strangely and having difficulty in breathing, so on the way to the case, you’re probably thinking, “Well, what would that cause … be causing that?” You might be thinking, “Drugs.” You might be thinking, “Trauma.” You might be thinking, “Mental health.” But to be honest, if somebody’s having difficulty in breathing and is hypoxic, they’re going to be acting strangely because they’re gonna be suffocating basically.
On arrival, the daughter greets you and tells you that her mother has a history of heart failure. Now, let’s be clear here. Left ventricular failure is only one part of heart failure. There’s different types of heart failure. There’s congestive heart failure, there’s right-sided heart failure, there’s the left ventricular failure, which is what we’re talking about today, and there’s different classifications of heart failure. So, essentially, she’s not been taking her medications. Well, that’s not going to help. Now, unfortunately, whenever there’s a left ventricular failure, all you can really do is provide medication therapies to try and relieve the symptoms because once the heart muscle has died or a part of it has died, it’s never going to be returned back to its original form. So, the medications that you are providing as a paramedic and as a general practitioner are designed to help relieve some of the signs and symptoms and to help reduce hypoxia.
The mother appears extremely short of breath, is using accessory muscles to breathe … Remembering what the accessory muscles were. You’ve got some up in your neck, you’ve got some around here in between your ribs, underneath the ribs, this subcostal regions, intercostal, suprasternal. So, you can get your head back in the books and have a look at those accessory muscles at any time … and is acutely confused. So, what that means to you is that if she does not have the capacity, the mental capacity, to make her own decisions, then you have the right to treat her against her own will; however, I’ve had this patient myself as a paramedic, and they are extremely difficult to deal with.
So, introduction then. The left ventricular is the most powerful pump of all the heart’s chambers, and when you have a look at an image of the left ventricle, you’ll see that it’s got the largest muscle wall, the largest … It’s the largest muscle, basically, because it’s designed to push blood around the body against a lot of resistance and against high forces. When it contracts, it pushes blood around the body against resistance, and therefore, the pump must pump at a great force. If the left ventricle becomes damaged …
So, for example, with a myocardial infarction, let’s say there’s a heart attack and then part of the circulation to that part of the ventricle is occluded, you’re gonna end up with a myocardial infarction, and longer term, you may end up with left ventricular failure. Eventually, the blood will flow backwards if it stops pumping effectively, which will result in fluid in the lungs. Now, when this occurs, it’s not necessarily fluid, but actually plasma, and as the blood gets pushed backwards, again, against a lot of resistance, the plasma inside the blood and in the circulation gets pushed back into the lungs under extreme amounts of pressure.
So, this is just an image of the heart that I found to try and exemplify what we’re talking about here. So, let’s go through this together. So, here’s the superior vena cava that comes downwards from the top part of the body. From the bottom part of the body, you have the inferior vena cava. Both these vessels end up emptying into the right atrium as it says here, the right atrium, which is the first vessel that the blood pumps into, it’s the first chamber of the heart. When it contracts, it pushes blood down into the right ventricle, which is all here. Don’t worry about these things for now. These are just the chordae tendineae and the pupillary muscles. But as you can see here …
Let’s compare the left and right ventricle. Here’s the left ventricle. Notice how thick the ventricle wall is, and that’s because it has to do more work in comparison to this side of the wall here. When the right ventricle, this one here, contracts, it pushes blood into the pulmonary system and into the lungs. As you can see here, right pulmonary artery, left pulmonary artery. Eventually, it becomes oxygenated and goes from the lungs into the left pulmonary vein, into the left atrium, or atria, and through into the left ventricle, which then gets pushed up here, and through the aorta and around the rest of the body. So, for some of you, that might be the first time you’ve seen that, but for many of you, you would’ve already known that, so it serves, really, just as a gentle reminder.
So, let’s talk a little bit about left ventricular failure. So, let’s say this part of the wall here has been damaged permanently by a myocardial infarction. First, what will happen is the left ventricle will try to maintain its pressure, so it will start to work harder, and you may not see any major differences in the first instances; however, over time, like any muscle, it will become bigger and bigger and enlarged to the point where it actually starts to fail. So, at the point that it starts to become enlarged, it will become less effective, less efficient, and then when it fails, when it starts to become less efficient, you will get pooling of blood into the left ventricle, the blood will move back up into the atria, and then you will get the back flow of fluid into the lungs. Eventually, you will get backflow of blood into the right ventricles, right atria until it comes back out and you end up with complete heart failure, and you may even go into cardiac arrest in the later stages.
Now, when the blood starts to flow back up here and your patient demonstrates signs of shortness of breath, if you have a listen to their chest with a stethoscope, you will hear crackling. That’s called pulmonary edema. The crackling in the pulmonary … the plasma that we just talked about entering the lungs and sitting inside the lungs, and you can hear the crackling. To keep this quite simple, it’s your job as the paramedic to, number one, reduce the amount of work the heart has to do, and that’s when you would use glycerol trinitrate, and number two, use diuretics, or anti-diuretics, such as furosemide, to be able to help relieve the pressure of that fluid from the lungs, helping the patient to excrete it. So, some ambulance services will allow you to use anti-diuretics.
This is basically what we’ve literally just talked about, and I’ve taken any major … I’m showing you where the blood flows backwards. Again, here is your thickened myocardium and you’ve got your backflow of blood, which will move back into the lungs and you’ll eventually end up with pulmonary edema in the lungs.
So, typical signs or symptoms of LVF … Now, just remembering, guys, that there is a continuum. You’ll have those patients who are hypoxic and acutely confused who are very close to cardiac arrest, you’ll have those patients who’ve maybe had a problem with their furosemide or their water tablets, and you’ll have everything in between as well. So, typical signs or symptoms include dyspnea, difficulty in breathing, and they tend to describe it worse when lying flat at night.
Imagine if you’ve got fluid built up in your lungs, and while you’re upright, it’s all pooling in the bottom and you can clear it by coughing and taking tablets, but then when you lay flat, essentially what you will be doing is laying that fluid flat across the chest, and that’s why most patients will tend to sleep in a semi-upright position. Now, what that means is they tend not to have a really good night sleep, meaning that they are lethargic, they are generally fatigued and aggravated and tend to sleep more throughout the day. So, difficulty in breathing, worse at night, so you will be called to patients in the middle of the night, and that’s just called orthopnea, difficult in breathing as well as dyspnea.
Patients will recall a sensation of drowning, they will have low-cinched SpO2 levels, which you can detect either by looking at your patient, they will look hypoxic, but to get an accurate reading, you’ll need to put your oxygen saturation probe on the finger. In later stages, extreme confusion due to hypoxia, they will complain of chest tightness, so you can’t rule out a myocardial infarction, so you have to do the full 12-lead ECG. And to be honest, the glycerol trinitrate that you treat these patients with is exactly the same GTN that you will treat acute coronary syndrome patients with as well. And, of course, we mentioned how there will be a sense of crackling in the chest upon auscultation.
So, the pre-hospital management focuses around providing oxygenation, giving nitrates to decrease the left ventricle pressure, and improving the output of the cardiac ventricle, so increasing cardiac output. According to the American Heart Association, the use of Aspirin in heart failure patients is still controversial. That’s because there are not any strong evidence, strong randomized control trials out there; however, you will see that Aspirin has found its way until ambulance service guidelines, and the evidence that does exist has been shown to help reduce mortality. So, you will be advised to give Aspirin in a 300 milligram format. Salbutamol may be used to allow relaxation of the smooth muscle and to help to clear the mucus and the fluids. It’s your job to help make the patient as comfortable as possible, treating any pain using anything like methoxyflurane or Morphine. And, of course, it’s so important you do undertake a full medical history as well as taking any medications to hospital with you because the hospitals find it really difficult to find out what medications the patients are on just while we’re waiting for the joined up systems to kick in.
Okay, so what we’ve talked about today, is we’ve talked about the blood flow through the heart, providing a basic recap of the circulation through the heart, the importance of the left ventricle in terms of the role that it plays in oxygenating the brain and the vital organs, and how the signs or symptoms of LVF relate to what’s going on in the body.