Heart Rhythms Part 1: Basic Heart Anatomy

One of the things I have been asked to do several times is my cardiac lecture. I don't mind it at all since it's a great way for me to stay proficient and up to date. I figure, by blogging it, my co-workers can have this as a reference and those not in EMS can learn a little about their own heart. This way, next time you're at your doctor's office and they hook you up to the heart monitor you can have some fun and try to figure out your own heart rhythm (OK, maybe not). Or you can just laugh at the mistakes on any one of the medical dramas currently on TV. We're going to start out with simple anatomy and progress from there. If you have any questions, please ask. This is going to be simplified.

The heart is a muscle that has four chambers. I find it easier to think of it as two separate pumps (right and left) based on it's function. There are the right atrium (upper chamber) and right ventricle (lower chamber) and the same on the other side (left atrium and ventricle). Blood comes into the heart via the superior vena cava (a big vein) and starts filling the right side of the heart while it's relaxed. Once both chambers of the right side of the heart (it's also happening on the left side simultaneously) are filled with blood, the atria are electrically stimulated and they contract. There is a one way valve separating the atria and the ventricles. The blood is forced into from the atria into the ventricles, expanding them. Muscles, when rapidly stretched, contract (Starling's Law). Just as the ventricle starts to contract, because of the stretching, it is also stimulated electrically. The ventricle then forcefully contracts ejecting the blood into the pulmonary artery (in the case of the right ventricle) which is again separated by a one way valve. Blood is then moved to the lungs where carbon dioxide is exchanged for oxygen. This is all that the right side of the heart does, receive blood from the body and pump it to the lungs. Blood returns to the heart via the pulmonary vein. It enters into the left atrium and begins to fill the left side of the heart. Once the chambers of the heart are full the process of contractions starts over. This time the blood is forced past another one way valve into the aorta, the largest of all arteries in the body. From there the blood is distributed to the rest of the body. That is the job of the left side of the heart, blood distribution to the body. The right side of the heart is smaller (the muscle tissue) because it does not require as much force to pump the blood to the lungs. Clear as mud?

In the illustration below it shows all of the major parts of the heart and it has arrows to indicate the flow of blood. The blue blood vessels are connected to the right side of the heart (it carries less oxygenated blood headed for the lungs). The ones in red are connected to the left side of the heart and are oxygen rich.

Now that we understand the physical layout of the heart I'll briefly touch on the electrical system. Cardiac cells are unique in that they all have the ability to produce an electrical charge (automaticity). If they were to do this at random the heart would fail to properly contract and the result would be an absence of blood flow. So to control this there is a very organized system in place. It starts in the right atrium with the sinoatrial node (sinus node or simply SA node). The electrical impulse starts there and goes through the atria causing them to contract. It then hits the atrioventricular node (AV node) which slow down the electrical impulse for a moment before sending it down the Bundle of His to the ventricles causing the ventricles to contract. The amazing part is that if one of the sections of the electrical system fails, the other sections of the conduction system itself act as a back up. While most heart beats are started by the SA node, if it fails to work, then other parts of the heart, such as the AV node, can still do the job (although with some draw backs).

Heart Rhythms Part 1: Basic Anatomy
Heart Rhythms Part 2: Sinus Rhythms
Heart Rhythms Part 3: Junctional Rhythms
Heart Rhythms Part 4: Ventricular Rhythms
Heart Rhythms Part 5: Premature Beats
Heart Rhythms Part 6: Heart Blocks

Chest Pain AMA

Just as shift change was happening we were toned out for a medical aid. We responded for a woman with chest pain. Upon our arrival we found our patient waiting for us in the garage. As she led us inside her house she explained that about 10 minutes prior to our arrival she had been driving home from dropping her kids off at school when she started having heart palpitations.She also experienced shortness of breath. She described it as a pleuritic chest pain that only lasted about 5 minutes. She also informed us that she had a history of anxiety and had taken a Valium when she got home to calm herself down. Our patient, a 46 year old woman, had had several episodes similar to this one over the past several months. Each time she had been seen by either the ER physician or her cardiologist but they had found nothing wrong with her heart. After doing a full work up, and not finding anything, she stated that her husband was on his way home and she would prefer to let him take her to the cardiologist instead of going to the ER. We signed her out AMA and went on our way.

This is an example of a heart rhythm that we are hoping not to find. In leads II, III, and aVF there are large humps that aren't supposed to be there. This is called tombstoning (it's shaped like a tombstone and the person is quickly headed for one) and is indicative of an MI. This person would need to get to a angio-cath lab right away.

Thanksgiving

One of the things that I am most grateful for this holiday season is my job. I am fortunate enough to have a job that I love, I am able to support my wife and growing family, and it's a job that most people across the country volunteer to do. Especially in these tough economic times I feel lucky to have this job. 

Here are some of the statistics on firefighters nation wide. While you're enjoying your day off with your family, take a moment to remember those that are working (fire, police, EMS, hospital staff, military personnel) to make you safe.


Happy Thanksgiving.



NFPA estimates that there were approximately 1,148,850 firefighters in the U.S. in 2008.  Of the total number of firefighters 321,700 or 28% were career firefighters and 827,150 (72%) were volunteer firefighters. Most of the career firefighters (74%) are in communities that protect 25,000 or more people. Most of the volunteer firefighters (94%) are in departments that protect fewer than 2,500 people. There are an estimated 30,170 fire departments in the U.S. Of these, 2,315 departments are all career, 1,790 mostly career, 4,830 are mostly volunteer and 21,235 are all volunteer. In the U.S., 13,352 or 44% of departments provide EMS service, 4,418 departments or 15% provide EMS service and advance life support, while 12,400 departments or 41% provide no EMS support.

Bum Fights

I find it interesting how groups of people stick together. We had just finished another call where the patient had signed out AMA. As we were pulling away the tones went off again. We immediately lit it up and headed for one of our shopping centers. AMR had been facing the other direction so we had a slight advantage but they were able to catch up and arrive just behind us. As we arrived we noticed a homeless man that was sitting in the middle of the parking lot bleeding from the nose. He had two other homeless there with him. According to the "friends" our patient had been punched in the face. We asked if they knew who did it and they clammed up. I guess they didn't want to betray another homeless person. We told them that we juat wanted to make sure that person was no longer around for our own safety. About that time PD showed up and took both "friends" aside to talk to them. Since our patient suffered trauma and was not willing to talk to us he got placed in full spinal precautions. He wasn't too happy with that but he still refused to talk to us.
 
Some of what we use when we place someone in full spinal precautions. They end up looking like this. It's not comfortable.

Street Racing

We were toned out for a TC in front of the local high school just after 0800. As we approached the scene we were able to see a 1977 Camaro that had the entire front end destroyed. We also could see the undercarriage of a pick up truck that had flipped onto it's side and come to rest against a fire hydrant. Amazingly enough, both drivers had self extricated from the vehicle. The driver of the Camaro was a 17 year old student driving his 16th birthday present. Both drivers signed out AMA (technically the mom signed out the 17 year old). After talking with PD we found out that there had been a third vehicle and all three were street racing down a 4 lane road. When the two vehicles crashed the third kept going.

A couple of photos of what can happen while street racing.

Drive safe.

How To Catch a Flu

Rampant Hypoglycemia

We were toned out for a female passed out on the sidewalk in front of one of our local grocery stores. When we arrived on scene there was a small crowd surrounding a heavy set woman in her early 50's laying on the ground shaking. Someone had grabbed their jacket and laid it down as a pillow for her. Every one of our fire apparatus is considered and ALS unit meaning that it's staffed with at least one paramedic. On my crew I'm fortunate enough to work with another medic. This can be challenging if the medics don't work well together but that's not an issue with us. We quickly grabbed s-spine and started our assessment. Witnesses said that she just kind of collapsed as she walked out of the store. After giving her some oxygen she started to come around a little bit. She was still very groggy and slow to answer our questions. We checked her sugar and it was 37. Bingo.

Lately, everybody that we run on has low blood sugar. Stub a toe, because the sugar was 42 and they were almost passing out. Short of breath...sugar 51. Fall....44. Altered....27. It's strange enough that my captain even said that either the medics he has worked with in the past were horrible and never checked sugars or there just a recent case of rampant hypoglycemia going on.

I started a line and as I began to give her some dextrose her husband came out of the store. He had been looking for her all over the inside. He told us the she did indeed have diabetes and that this happened very rarely. After she had the sugar on board she was totally coherent. She told us that she must have taken her fast acting insulin this morning instead of the slow acting and that was why her sugar was so low. We cleared c-spine and loaded her onto the gurney.

For those of you who don't know here are some of the signs and symptoms of someone with low blood sugar levels.

Frostbite at 58

Like most major metropolitan areas we have some homeless people that live in our city. We know most of them by name and they are generally happy to see us even when we drive by or if they catch us going to the store (more so than your average citizen). Side note, we were talking about this at the station and we figure it's because we are the only people that are actually nice to them and will talk to them rather than just walking away and ignoring them. I digress. We were called to one of our local shopping centers that is frequently from where the homeless call 911. We arrived and found one of our regulars in his wheelchair. When he saw us he yelled at another homeless man for calling us. Our patient said that he was worried that he may have had frostbite from a couple of nights before and that his toes really hurt. We pulled of his shoes and socks and noticed that his feet and toes were soft and pink. No chance that he had frostbite. I doubted it anyways since it hadn't been below 60 degrees in quite a while. As AMR pulled up he said that he wanted to finish his drink. Knowing him like we do we knew that he wanted to finish his beer. We told him that he knew better than that. As we helped him onto the gurney  we found out that he had had a bowel movement. Oh the joys of this job. At least I didn't have to sit in the back of in ambulance with that lovely combination of smells.

Toes with severe frostbite tissue damage.

Structure Fire

At just after 0300 the lights turned on and the tones sounded. It was a full first alarm response for a structure fire. We quickly donned our turnouts and jumped into the engine. First, I grabbed the TIC and handed it up to my captain. I then slid into my seat mounted BA, pulled my shoulder straps tight and put on my headset. After letting my engineer know that I was ready to go I finished putting on my BA by fastening my waist strap. After that was done there was time to sit back, listen to the siren, watch the red and white lights reflect off the houses and think this is the greatest job.

We were the second unit to arrive on scene. It was a fire that had originated in the fire place but had somehow started a fire in the chimney. While the first in crew started their initial attack on the chimney from the back yard we were instructed to check for extension (to see if the fire had spread to other parts of the house, on the inside of walls, up to the attic, etc.). I grabbed an attic ladder (10 foot folding ladder that's used to make access scuttle holes). We found that the interior of the house was smokey but not that bad. Once upstairs in the bedroom that was against the chimney my captain used the TIC and determined that the there was a slight chance that it had spread up near the roof line. After checking out the attic space we determined that there was a large beam that was being heated and that was what was showing up on the TIC. We were able to determine that there was no extension into the house without tearing it apart. The chimney was not so lucky. the initial attack crew had to take most of the facade off to fully extinguish the fire.


After the fire was out my captain and I saw the owner of the house. He was approximately 50 years old and was coughing a lot and having an obviously difficult time breathing. I asked the owner if it would be OK to medically check him out. He told me that when he had first noticed the fire there was a six inch hole in the facade of the chimney through which he could see the fire. He decided to grab the garden hose and put it out himself, while wearing PJ bottoms and no shirt. When he introduced water to the fire it quickly turned to steam. When water is converted to steam it expands at more than 1700%. This forced super heated gases and smoke right out that hole and into the would be firefighter's face, causing him some respiratory problems. I placed my patient on some oxygen and did a thorough assessment. We even have a machine that will check how much carbon monoxide is in the blood stream. After about 10 minutes of oxygen my patient felt much better and was no longer hacking up a lung. I told him that he better leave the firefighting to the pros. He told me that's exactly what his wife had said. Once he signed out AMA we were cleared to go back to our station.

We arrived at that awkward time where you don't want to be up but there's not really time to go back to sleep either. I chose to lay on my bed and relax. What a great job.

Double Whammy

We were toned out for an altered person. When we arrived on scene we were met by the patient's wife. She explained that her husband, who is 67, had been very ill and that he was in need of both liver and kidney transplants. Walking into the bedroom I found that my patient was alert enough to look at me when I entered the room but that was about all. He kept repeating in Spanish, "Me voy. Me voy." I'm going. I'm going. Where he was headed, I don't know (if he meant anywhere but the hospital.) The patient's wife informed us that he had just been released from the hospital for hyperammonemia (high ammonia levels in his blood) which left him in this exact condition.

We did a complete medical exam and could find no other reason for his altered state of consciousness. We placed him on oxygen, started an IV and sent him to the hospital. Without a transplant soon the outcome of this patient does not look to good.

You're Gonna Feel Weak

The tones went off and we hopped into our bunker pants and jumped on the rig. While tearing down the street with lights and siren blazing dispatch informed us that we were responding for a 96 year old male that was feeling weak. My first thought, well DUH! Your 96 years old! What do you expect? Now deep down I know that people are calling because they are feeling something that is out of the ordinary for them but I couldn't help but think that this guy was just lucky to be feeling.

When we arrived on scene we were met by my patient's daughter. She led us to the backyard where she had left her father in the sun (because his skin color wasn't right). She gave me a decent report on his current medical problems, his past medical history, allergies and current medications. The report was good enough that I asked her if she was nurse, which she was (which slightly frightens me that a nurse would place someone that was very pale in the sun, as if it were the cure). My patient had recently (two weeks ago) undergone heart surgery and had a pacemaker/defibrillator implanted.
  AMR arrived while we were getting the heart monitor on him and getting our first set of vitals. I gave a quick report just as we got a BP. 66/42. I guess that explains why you're not feeling so well and you look like you just saw a ghost. We quickly move him to the gurney and lay him flat. Once in the back of the ambulance the AMR medic started a line. After making sure that he didn't need any more help we cleared the scene.

Hopefully the guy makes 97.

Going Up (Or Not)

One of the many things that we as firefighters have to know how to do is to respond to an emergency in an elevator. For the most part, all we are going to do as firefighters if people are stuck in an elevator is make sure everyone is ok, make sure the elevator repairman has been called and keep everyone calm. We only get to force our way in if there is an emergency ongoing inside the stuck elevator.

We have several options depending on the type of elevator. Most elevators are piston driven, meaning there is a giant piston underneath that raises and lowers the car. There's no way it's going to fall. The nice thing about this type is that we can go to the hydraulic pump and bleed off the line and slowly lower the car to the next floor. We could also open the doors to the elevator shaft on the floor above the car and use ladders to make entry through the roof hatch. (Did you know there was a roof hatch on most elevators?) We can also use our auto extrication equipment (and equipment off a heavy rescue) to make our own entry into the elevator car. The other type of elevators use cable to suspend the car. These are used in high rise buildings because of the heights involved. Along with the previously stated methods we can make a rescue from an adjoining car. This is very dangerous and left as a last resort.

Escalators are another thing with which we have to deal. If someone were to get stuck we would shut off the escalator (shut off switches are located at the top and bottom of escalators). We would then dismantle whatever we needed to to get our victim free.


I found this clip while researching elevators and escalators. I thought it worthy of sharing.



One of the "extra" things that I did learn was how to keep an elevator from stopping for other people while traveling from your floor to your desired floor. Simply press and hold the close door button and the button for the floor on which you wish to go for 5 seconds. I haven't tried it but I saw it on YouTube (which means it must be true, right?). If you have a tall building and feel like trying it out let me know how it goes. Next time I'm in one I'll try it.

A Great Article I Found Online

Elected officials, media walk in the boots of a firefighter

By Kristofer Noceda
The Oakland Tribune

Posted: 11/07/2009 05:52:58 PM PST

Updated: 11/07/2009 06:25:23 PM PST

SAN LEANDRO — Responding to emergencies. Handling traffic accidents. Helping transport victims to the hospital. Searching for and rescuing people. Yes, firefighters do more than put out fires.

Local elected officials and members of the media learned that firsthand Saturday by walking in a pair of firefighters' boots — and turncoats, helmets, masks, gloves and other heavy equipment — through Fire Ops 101. The program, put on by the Alameda County Fire Fighters Association and Alameda County Fire Department, was held at the training center on Lola Street, just off Davis Street. It was designed to place participants in controlled situations to gain a better understanding of what those riding on the big red engines do for a living, said John Torres, firefighters association president. "We want them to get in and see exactly what we do," he said.

Assemblyman Alberto Torrico, D-Fremont, called it a "sobering experience." "Everything we did showed that four firefighters are needed," he said, referring to an ongoing debate on whether a fire engine should be staffed with three or four firefighters. "It is critical they have full staffing because without it we are putting the victims and firefighters at risk."

The 10 participants were split into teams and made their way into five scenarios. This reporter was part of the "White" team, which included Torrico, Brian Dinsmore of KPIX Channel 5 and Robert Souza of the Castro Valley Forum newspaper. The group first was tasked to help safely remove a victim out of a car accident by stabilizing the vehicle and using tools like the Jaws of Life extrication device to gain access to the victim. It was an eye-opening experience for Diana Souza, a San Leandro City Council member, who like many participants had no idea that tools used to rescue people from car accidents can get outdated quickly with the constant new designs of vehicles. "Manufacturers of cars should get in touch with firefighters and others charged as first responders to these emergencies so that they can have the most up to date equipment," she said.

After removing the person trapped in the car, the team then transported the victim to the emergency medical service station. Here, firefighters provided treatment, which can include performing CPR, until an ambulance arrived and transported the victim to a hospital. About 80 percent of all calls are emergency medical service-related, officials said.

Next came a ventilation scenario. Participants climbed 100 feet on a fire engine ladder and broke through roofs using a chain saw and a large hammer. Then, as one firefighter put it, the fun came. Taking turns and aided by firefighters in front and behind, participants — equipped with oxygen tanks and masks — went into a smoke-filled building and extinguished a blaze by firing a water hose.

The last scene had the team go into another smoke-filled, pitch-black building to find and rescue a person by using thermal imaging cameras. Many participants were left with a newfound appreciation for what firefighters do daily. "We hear all these stories about fires, but you can't get a real feel until you actually put the gear on and experience what (firefighters) do," Diana Souza said. "It was a great experience and I'm definitely going to encourage all council members and other decision makers to do it."

AAA (With a Hose?)

I had just finished unwinding by reading my book in bed (a book on some of the issues in medicine) and had just turned off the light when the tones when off. My first thought, at least I wasn't asleep yet. Then we were told that we were responding for a person locked out of their vehicle. Now I don't know about you but when I have locked my keys in my car I have never thought of calling 911. I could understand it if it were hot outside and there was a kid was locked in the vehicle. Hey, even a dog. But at 2330, outside a restaurant, in mild temperatures, and it's only a guy that's locked out of his minivan. Really?  Come to think of it, I've changed tires too. I used to give a friend that's a CHP officer a hard time about being AAA with a gun. I guess I'm AAA with a hose.

The funny thing is, we are good at it. We had the guys vehicle unlocked in about 3 minutes. We could be faster but that involves the owner having to replace a broken window. I really don't mind going out to do this. After all, I chose to serve the public. I just wish they wouldn't call 911. Use the non emergency number for you local fire department.

By the way, the 24 hour number to AAA is 1-800-AAA-HELP.

You're Making Too Much

I don't care how little they are paying you, if your fire engine comes with a surf board, you're getting paid too much!

Repeat Customer

We were toned out for a fall with injuries to a residence that is literally 5 or six houses away from the station. It's the second time this month that we've been there. The gentleman that lives there is in his early 80's and has a long list of medical problems. He called us out today because he fell and broke his ankle (the last time we were there he had fallen and twisted the other ankle). I quickly ran through my assessment but as I did I could sense my patients frustration growing. I could almost hear his thoughts, "Why are you asking me all theses inane questions when it's obvious that I broke my ankle?" I wasn't too concerned with the broken ankle. I wanted to know why he fell. I finally got out of him that he did in fact feel dizzy before he fell. Just about that time the other firefhgter got the blood pressure, 86/52. Too low. While I started an IV to give my patient some fluids to bring up his blood pressure the other firefighter splinted the ankle with a vacusplint and placed an ice pack for the pain and swelling.

As we were loading the patient into the ambulance I told him that if he wanted to see us so bad, next time just stop by the station. We're just down the block. He laughed and said he would.

The Nature of Firefighters

I once saw a comic strip that depicted a little boy talking to a firefighter. The boy said, "When I grow up I want to be a firefighter." The firefighter replied, "I'm sorry, you can't do both."

So true.