At the Heart of the Matter
The heart is part of the cardiovascular system and the centre of our existence. Some say it is our soul that makes and defines us but it is the heart that keeps us moving, breathing and being. According to the World Health Organization, cardiovascular disease is the number one cause of death globally with 85% of those deaths being due to heart attack and stroke. But how many of us heed the warning?
Did you know the heart is actually the body’s hardest working muscle? The heart is continually working whether we are at rest, active or asleep. For us to function at any level our body not only needs to be furnished with nutrients and oxygen but also requires a system that removes waste and carbon dioxide. The blood is responsible for this process, but it is the heart that makes it possible.
Located near the centre of the chest, the heart is made up of four chambers that pump and circulate blood, oxygen and carbon dioxide around the body. Each of the chambers has its own function and special cells for regulating the heartbeat; failure of any part of the system can lead to disruption of function and sometimes death. The four chambers are separated into left and right by a strong wall of muscle with valves separating the upper and lower chambers, known as the atrium and ventricles respectively. The right atrium receives deoxygenated blood from the body which then passes to the right ventricle on its journey to the lungs where carbon dioxide is expelled, and oxygen taken up. This oxygenated blood then returns to the heart via the left atrium, where it then passes into the left ventricle to be pumped around the body via the aorta. As with all muscles of the body, the heart also needs oxygen to function and it receives its supply of oxygenated blood via branches from the coronary arteries.
Blood is able to circulate around the body because of electrical pacemaker cells within the heart which cause a strong contraction, forcing blood into and out of the heart. The heart beats in two phases: systole (contraction) and diastole (relaxation), comprised of four stages:
• Atrial systole – This lasts about 0.1 seconds and both atrium (upper chambers) contract pushing blood into the ventricles (lower chambers). The flow of blood is controlled by valves which prevent the blood from flowing back into the atrium.
• Ventral systole – This lasts a little longer, about 0.3 seconds, and both ventricles contract, forcing deoxygenated blood back to the lungs and oxygenated blood around the body.
• Atrial diastole – Relaxation of the atrium lasts for about 0.7 seconds. During this time both of the atrium fill with blood.
• Ventral diastole – The valves between the upper and lower chambers are forced open by the pressure of the blood in the upper chambers. This allows blood to flow passively into the lower chambers. This phase occurs just before atrial systole
It is this activity we see on an electrocardiogram (ECG) represented by waves, and which doctors refer to as the PQRST complex. When this pattern is disrupted and all cells try to lead the cycle, it can result in an irregular heartbeat or atrial fibrillation. On average a healthy adult heart beats 60-80 beats per minute but in well-trained athletes the heart is more efficient and can beat as low as 40 beats per minute.
You can monitor your heart rate by feeling your pulse. Pulses can be felt at the wrist, in the neck and in the foot, where the arteries pass close to the surface of the skin.
When the heart is working efficiently, we do not normally pay attention to it, unless we undergo strenuous activity and feel it beating faster and harder than normal to cope with the increased demand of oxygen that we need to generate more energy and fuel for our muscles to function. But when things go wrong it is hard to ignore. Quite often people do not know they have a problem and the first sign is when something serious happens. Measuring our blood pressure (the systolic – contraction and diastolic – relaxation phases of the heart cycle) is one way of detecting early signs of problem with our heart. Normal blood pressure is 120/80mmHg; it may be lower in athletes or adolescents, but higher values indicate a greater risk of developing serious heart complications or suffering a stroke.
Next week we will talk about what happens when the heart goes wrong and steps you can take to get back on your feet. Also how you can change your lifestyle to protect your heart.
Kim Jackson is a UK-trained physiotherapist with over 20 years’ experience. She specialises in musculoskeletal pain and dysfunction including back pain and sciatica, stroke and other neuro conditions plus sports physiotherapy, having worked with local, regional and international athletes and teams treating injuries and analysing biomechanics to improve function and performance. She is registered with the Allied Health Council and is a member of PASL. She currently works at Bayside Therapy Services in Rodney Bay, O: 458 4409 or C: 284 5443; www.baysidetherapyservices.com
A happy, healthy heart is the centre of our existence but we only appreciate its value when something goes wrong.