Songs come in all genres; disco freaks have "Stayin' Alive" (Bee Gees), "Dancing Queen" (Abba), and "Girls Just Want to Have Fun" (Cyndi Lauper) for popsters, "Hips Don’t Lie" (Shakira) for Latin salsa fans, and if hankering for Country, "Achy Breaky Heart" (Billy Ray Cyrus). But these aren’t merely songs; these are lifesavers. Fast, rhythmic numbers to play in your head when performing CPR, cardiopulmonary resuscitation, for cardiac arrest (CA). Hopefully reading this will help avoid CA, inform how to spot signs of impending CA, how to learn CPR, and the role of AEDs.

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As doctors, we are privileged to see people in their darkest hour, help many, cure some, and always reassure. But nothing beats resuscitating someone who, without attention, will die 100% of the time. And you can do this too.

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Cardiac arrest is sudden cessation of the beating heart and as it stops, there are dire consequences; blood is not sent to the lungs to collect oxygen and drop off carbon dioxide, and the organs neither receive the oxygen and nutrients they require nor can expel the carbon dioxide and waste products they produce. One by one, they die, and eventually, in mere minutes, so does the poor person suffering the arrest.

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For the etymologists out there, “arrest” originates from Latin, *re-stare*; to remain, or stop. Stopped hearts kill around 100,000 Brits and 300,000 – 450,000 Americans yearly, more commonly they are men and tend to be older folk.

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Risk factor awareness and taking action to address such factors can reduce the number of arrests. And the more people capable of performing CPR, the more patients suffering an arrest can be resuscitated...or in plain English, saved from sudden death. To provide perspective, around 5 – 10% suffering CA outside hospital survive; whereas among hospital in-patients, that number climbs to 20 -25%. According to a meta-analysis of 38 studies including 16,933 patients, around 2/3 were still alive after ten years, so CPR has long term benefits!

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The heart has its own electrical generator, or pacemaker, the sino-atrial node, which sends signals down cellular wires called the Bundle of His, to an electrical sub-station, the atrioventricular node. These electrical impulses coordinate orchestrated contraction and expansion of the four heart chambers. If disordered, one has an aberrant rhythm (arrhythmia), often foreshadowing ineffective cardiac pumping. That diseased rhythm might be asystole with no contraction, or ventricular fibrillation where the heart looks like a “bag of worms” - wiggly muscle but no blood being pumped; not to be confused with atrial fibrillation, a very common, less serious although often troubling condition. Look out for a discussion about atrial fibrillation on a future episode of Join the Docs!

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Eccentric rhythms commonly follow impairment of blood supply to heart muscle due to arteries blocked with gunk, (atheroma), or when high blood pressure is associated with a stressed cardiac system. This can be a slow, progressive situation, or a sudden heart attack (myocardial infarction or MI) where an area of heart muscle loses blood supply and dies, either blocking electrical signals or sending out false signals in its death throes.

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Avoiding MI is largely achieved by controlling weight, increasing activity, modifying diet, not smoking at all nor drinking to excess and having blood lipids and pressure checked regularly. Knowing family history risk factors might dictate other helpful steps.

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Other causes for CA include structural or functional problems one is born with, dodgy valves or enlarged heart muscle disease (cardiomyopathy). To remember all the causes, doctors construct memory tools and for CA we use the “5 H’s and 5 T’s”

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Hypoxia: oxygen shortage due to respiratory diseases or a low oxygen environment, such as being at altitude or perhaps in an airplane – modern airliners are pressurized to a cabin altitude of 6,000 feet or 1,820 meters – high enough such that if slightly unfit one might feel a tad breathless. Many commercial aircraft now carry medical equipment and trained personnel in case there isn’t a doctor on board. In one study (Journal of the American Heart Association (AHA) [LINK]) of people who suffered CA on an aircraft, 15% survived to hospital discharge and those arresting in proximity to a plane, 44% survived. If one has cardiovascular disease take medical advice before flying.

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Hypovolaemia: where circulating volume of blood is reduced as in trauma – less circulating blood means less oxygen carriage and higher likelihood of cardiac issues. In the same vein - a deliberate pun – anaemia (anemia for our American listeners!) can also increase the risk of cardiac events like arrest;

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Hydrogen ion: where blood becomes more acidic such as in various acute illnesses

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Hypo/hyperkalaemia/magnesium: reduced (or increased) potassium and magnesium levels. A colon or rectal tumor can produce large volumes of potassium-rich mucus inducing irregular heart rhythms. Or arrest. Certain diuretic medications to treat hypertension also deplete potassium;

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Hypothermia: cold temperatures can cause CA. “Wild,” or cold-water swimming is popular, but carries risks of bad rhythms and pulmonary edema – literally drowning from the inside.

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Toxins: poisons and drugs can cause potentially fatal heart rhythms including amiodarone, a medicine ironically used to treat heart conduction problems

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Tamponade: where fluid accumulates in the sac around the heart, preventing full heart expansion;

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Tension pneumothorax: where a lung is pierced, trapping air around the organ;

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Thrombosis (coronary): blocked heart arteries;

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Thrombosis (pulmonary): blocked lung arteries. Diabetes can be a culprit in several ways; by blocking small cardiac blood vessels, damaging nerves preventing one experiencing tell-tale symptoms and throwing body chemistry into disarray. So put that soda down! Frank, but thankfully rare, electrical abnormalities like Wolff-Parkinson-White syndrome and Long QT syndrome, may cause CA throughout life. Any sudden mood change – anger, depression and sadness can also induce CA; one can truly die of a broken heart. But don’t turn to recreational drug use; cocaine, ecstasy, morphine, and even cannabis kills otherwise healthy people by CA. Spinal cord injury and a blow to the chest at a specific point in heart rhythm, e.g. by a baseball can produce CA in an uncommon condition, Commotio cordis. Based on CA survivor reports, about half experience flu-like symptoms, chest pain, nausea, palpitations, breathlessness, fatigue, dizziness up to 2 weeks before. If that sounds familiar, seek medical help. Just before an arrest one might feel chest pain, palpitations, dizziness, being lightheaded, weak or faint, then passing out. If you see someone suddenly collapse, possibly gripping their chest, not breathing and do not respond if you shout at, or shake them, assume this may be a cardiac arrest. In a commanding manner tell someone nearby to call the emergency services (999 in the UK and 911 in America – always

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know the local emergency number wherever you are in the world!), provide the location and demand an ambulance and paramedics attend and then return to tell you they have done as told. Then have them search for an AED – an automated external defibrillator – that can be a lifesaver. Familiarise yourself with what they look like and how they work – these are intuitive devices that can detect a heart is not beating and shock it into action, but the time to learn about them is not when someone is unconscious before you. Look for a pulse in the neck or groin where arteries are larger and easier to find than the wrist.

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This is where performing CPR comes in, but rather than endeavor to teach it here, please find and complete a local course. For instance, in the UK, many organizations offer courses such as St. John Ambulance ([LINK]) and in America, the AHA ([LINK]) Also, if your workplace, sports club, or anywhere you frequent does not have an AED, encourage them to get one. Anybody can save a life, maybe you! Glenn Hoddle, a friend to us at Join the Docs, and for the one person out there who doesn’t know, he is a fabulous British footballer who has also managed at the highest level, recorded pop songs, and worked as a pundit, was in a London TV studio on his 61st birthday. An otherwise fit guy, he suddenly fell backward, unconscious. Were it not for Simon Daniels, a sound technician who was CPR trained, Glenn would have died that day in 2018. Now, post-cardiac surgery and implantation of an internal defibrillator, he is well, working, and full of the joys of spring. You can learn more about Glenn and his life in the special episode we made together ([LINK]).

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This problem is real; please don’t let it affect you or those you love. Learn CPR, all about AEDs, and choose your song should you ever need a rhythm to be your resuscitation theme song; maybe the inappropriately named "Heartbreaker" by Mariah Carey and Jay-Z or NSYNC’s "Bye Bye Bye"! Keep that heart pumping!