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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blood doping, another PED

Wednesday, December 14, 2016

Erythropoietin (EPO) is a great drug for people who have chronic anemia (low red blood cell count) because of chronic disease. It stimulates the bone marrow to produce red blood cells and is useful for those with chronic kidney disease including those on dialysis, cancer, chemotherapy and inflammatory bowel disease. For the most part, these are the only people who should be taking this medication. But  don’t tell that to endurance athletes who want the benefit of extra oxygen carrying capacity in their bloodstream. Blood doping is not legal, it acts like a performance enhancing drug and has life threatening complications.

Erythropoietin is manufactured within the kidney and is very sensitive to the body’s environment.  Receptors can judge the amount of red blood cells within the bloodstream and if there aren’t enough, the level of EPO rises and causes the bone marrow to manufacture more red cells. Red cells contain hemoglobin, the molecule that attaches to oxygen in the lung and delivers it all the organs and tissues in the body, including muscles. Muscles need oxygen and glucose to function aerobically and get maximum performance. The more oxygen that can be delivered, potentially the longer the muscle can contract and the further and faster an athlete can run.

EPO is very sensitive to the body’s hypoxic (hypo=less +oxic=oxygen) stress, meaning that if oxygen concentrations in the bloodstream decrease, even over a short period of time, EPO concentrations increase, more red blood cells are manufactured and the concentration in the bloodstream increases. More hemoglobin presumably means more oxygen deliver and the hypoxic stress is relieved.

Patients with kidney disease, or those who become anemic from cancer or chemotherapy, cannot generate enough natural EPO to stimulate the bone marrow. Fortunately, over the past generation, pharmaceutically created EPO can be injected to help treat anemia and allow a better quality of life. More red cells allow the patient to be able to not feel constantly short of breath or weak.

Now imagine an endurance athlete who would like the benefit of 5 or 10% more red blood cells and oxygen carrying capacity in the blood. Not only would the length of activity be increased for training but so would the speed. The Olympic motto “faster, higher, stronger” “citius, altius, fortius” was meant to be achieved by perseverance and training, not necessarily living better by chemistry. Injecting erythropoietin or its cousin, the long acting darbypoietin would be a short cut to the hours spent training. It comes with a cost and that is the increased risk of stroke and heart attack. Too many red blood cells can cause blood to sludge and not flow easily through the narrow blood vessels in the body…arterioles, venules and capillaries.

EPO was a chemical way to enhance the body. Old school blood doping used more crude methods. An athlete would donate a unit of blood (about 500cc or a pint) a month or more before a competition and store it. Red blood cells have a shelf life of about 90 days if cared for properly and during that time, the body would gradually replace the lost blood. Just before the event, the blood would be transfused back into the athlete and voila…more oxygen carrying hemoglobin magically available to help performance. Same risks as EPO for heart attack and stroke.

The body’s naturally occurring EPO has a different chemical signature than artificial EPO, so testing has caught up can tell the difference proving who has been less than nice should they inject the drug.

There are legal ways to blood dope, if you have enough money. At altitude, the air contains less oxygen than it does at sea level. The body’s receptors recognize this oxygen deficiency causing EPO levels to rise and force the bone marrow to create more red blood cells to compensate for fewer oxygen molecules available with each breath. Unfortunately, training at altitude is less efficient than training at sea level, so the athlete needs to sleep at higher altitudes and train lower down. This is expensive and more than a little inconvenient. Nike developed a high-tech solution called Project Oregon. The company built a tightly sealed house in Portland where filters could decrease oxygen in the air inside to a level found at 12,000 feet. Athletes sleep at altitude and walk out the door to train at sea level. Nice if you can afford it.

There are opportunities to bend the rules. Blood doping is not legal and is potentially life threatening, however your body can be tricked into doing it legally by the letter of the rule, not necessarily by the intent. It has been a long time since the concept of a level playing field for all actually mattered.

 

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