sudden death: ventricular fibrillation: V Fib

Sunday, July 9, 2017

Sports terms make their way into our everyday world. From closing a slam dunk deal and being thrown a curve in a relationship to chasing a dream by keeping an eye on the ball, our language is peppered with sayings that aren’t to be taken literally. Then there is sudden death, a term that bounces back and forth from cardiology to sports overtime and back again. In medicine, sudden death is very black and white, marking the second when the heart stops beating, blood stops pumping and the brain and other organs stop working. While in sports, the final score ends the game, in medicine there is a chance at redemption, if the heart can be quickly restarted in minutes or less, the brain and body may recover. That is a big may and the final outcome may not be evident immediately.

Imagine being in the stands, cheering for your favorite team, when a player collapses. Imagine being in the stands when Dutch soccer team, Ajax, takes the field. Early in the game, a young 20-year-old player named Abdelhak Nouri collapses to the ground. Initially, there is little concern; after all it is soccer and players routinely dive to draw a penalty. Bu there was no foul and he lay motionless as the game quickly stops and medical staff rush on the field and start CPR. An automated defibrillator (AED) is used while screens are held around the scene to provide some privacy in a stadium filled with fans. But unlike television, Mr. Nouri doesn’t immediately stand up, he is unconscious and while his heart has been shocked and restarted, the brain and body haven’t yet recovered and he is placed on a ventilator, a machine that breathes for him, as he is helicoptered to the hospital and kept in a medically induced coma to hopefully allow his brain to recover.

The heart is an electrical pump. Sudden death occurs when the heart’s electrical system short circuits and the regular electrical pattern that signals heart muscle to beat is lost. Instead of normal sinus rhythm, a coordinated signal to every ventricle muscle cell to contract at the same time and pump blood to the body, the chaotic electrical rhythm causes each cell to contract randomly. The ventricles, the lower pumping chambers of the heart, sit their jiggling like a bowl of Jell-O instead of squeezing like it’s supposed to do. Ventricular fibrillation (V Fib) is not compatible with life and the only treatment that works is electricity, shocking the heart back into a regular rhythm,

normal sinus rhythm

ventricular fibrillation

 

With the advent of AEDs, bystanders can become lifesavers, if V Fib is the reason a person collapses and dies. CPR is the temporary stopgap that can provide some blood flow to the brain until the AED gets to the patient’s side, but CPR doesn’t fix what’s wrong. The AED is almost foolproof and walks the bystander through the steps of providing a shock if the cause of death if a shock is appropriate (some people have sudden death and the abnormal rhythm is not V Fib), delivering a shock is as easy as starting a car. And a reminder to those who are afraid of making a mistake…the victim is already dead, they can’t get any worse.

 

If the AED shock works and the heart restarted, hopefully, paramedics or EMTs are there to take over and then the hard work begins. Unless the person wakens immediately, the basic vital signs need to be controlled and stabilized, from breathing to blood pressure, the body needs help in getting regulated. Once at the hospital, an unconscious survivor of sudden death may be cooled just a little to help protect the brain and kept in a coma while the dust settles. Hopefully, the victim wakens and returns to normal function. That is not a given.

Sudden death happens suddenly without warning. Cheating death can only happen when bystanders are there to start CPR and find and use an AED. When elite athletes collapse, it is a reminder that anybody can become a victim and anybody can become a hero.

***

A reminder that here are two type of fibrillation:

  • Ventricular fibrillation affects the lower chambers of the heart that pump blood to the body and is not compatible with life.
  • Atrial fibrillation is a common condition affecting more than 5 % of the population and describes the inability of the upper chambers of the heart to beat in a coordinated fashion. This is not an immediate life threatening condition, though long term complications do exist
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passing out

Monday, April 3, 2017

Fans watch where the action is but video cameras record all, including what happens well away from the play. Low motion instant replay is usually saved for highlights or controversial plays, but for Philadelphia Flyer Michal Neuvirth, those cameras captured him collapsing in his goal, 100 feet away from the puck Without warning, Neuvirth fell to the ice and remained motionless for a few minutes until he gradually wakened and was rushed to the hospital. He was observed overnight, and with initial testing being normal, he was discharged home, no doubt to be poked and prodded to find out just what happened.

Passing out is never normal. At its very basic, the purpose of the body is to protect the brain at all costs. Brain cells need very little to function, oxygen, sugar and that’s about it, but it takes a complicated factory to deliver those two basic goods. A person needs to be able to breathe to get air into the lungs, where oxygen needs to be extracted and tacked onto red blood cells. The heart pumps those cell through arteries to the brain. Glucose is added to that oxygen supply when digestive system extracts glucose from food and dumps it into the bloodstream.

With those two building blocks, a person will be awake if two structures in the brain are working. The reticular activating system, the on/off switch in the brainstem, needs to be in the on position and at least one hemisphere of the brain needs to work. Blood supply needs to be cut to one or both of these parts of the brain for a person to become unconscious.

It may be a true emergency when a patient has a syncopal event, meaning that they passed out. If the patient remains unconscious, treatment and diagnosis happen together. Blood is tested for low blood sugar (hypoglycemia), a dose of Narcan might be given in case the person overdosed on a narcotic and an EKG with a heart rhythm strip is done, looking for a heart rhythm disturbance. Most often, though, the patient is awake by the time they are seen by the doctor and the detective work begins to look for clues as to the reason why the patient passed out, make certain that no disaster has occurred and hopefully prevent another passing out episode.

Passing out often is a fluid delivery problem. Cardiac output measures how much blood the heart pumps per minute. Enough output and the blood pressure is maintained to push blood uphill to the brain. The cardiac output formula is relatively simple:

      Cardiac output = Stroke volume x Heart Rate

Output equals how much blood is pumped per heartbeat multiplied by how often the heart beats per minute, and is a measure of how effective the heart is in meeting the body’s and the brain’s demands for energy. Problems may exist with the heart rate and rhythm or with the red blood cells and fluid. Anemia (low red blood cell count) or dehydration (decrease fluid in the body) may decrease how much blood is pumped per heartbeat. A heart that beats too slow, too fast or not at all, will also decrease cardiac output.

Some problems are not very serious, like a vasovagal episode, where the heart slows and blood vessels dilate because a noxious stimulus that stimulates the vagus nerve. Imagine a medical student fainting when he sees his first operation or a patient who passes out because of pain. Other causes can be life threatening, like a massive pulmonary embolus or blood clot to their lung (25% of patients with PE present with sudden death), a structural problem with the heart or a major electrolyte crisis in the body.

ESPN reported that Mr. Neuvirth had been recently ill recently with a virus infection and perhaps his syncope was due to dehydration. Standing in full equipment can make a goalie sweat up a storm…but while dehydration is a possibility, the big worry is whether Mr. Neuvirth had a heart rhythm abnormality, an electrical disaster like ventricular fibrillation nor ventricular tachycardia. When the bottom half of the heart does not get an organized electrical signal, it can’t squeeze in a coordinated fashion, it can’t squeeze, blood doesn’t flow through the body, including the brain, and the patient can pass out. V fib and V tach may be the cause of sudden death.

Since the patient is usually not on a monitor when the event happens, and if no other easy diagnosis can be found to explain the syncope, admission to the hospital to watch the heart rate and rhythm is usually the safest plan. Sometimes a clue can be found on the EKG or during observation, but often not. The patient is usully discharged home with no solid answer but with the expectation that further tests might need to be done. Since people live in the real world and not a hospital bed, people can have their hearts monitored in the real world for durations of 1-2 days or even months at a time. Every heartbeat can be recorded and analyzed fro potential problmes.

The treatment of syncope depends on the cause but from a practical standpoint, sometimes the cause is never found. The question then becomes, what advice should be given to the patient regarding activity. There is no right answer when the diagnosis is not known. In the ER, the unknown syncope decision is easy; the patient needs to stay in the hospital to be monitored. But once the dust has settled, it’s a risk-reward discussion between doctor and patient to decide when it’s safe to return to full activity, whether that’s work, driving a car or playing goalie in the NHL.

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