Heart failure (Part one): What is it?

Written by: Dr Peter Clarkson
Published: | Updated: 06/06/2023
Edited by: Lisa Heffernan

The term ‘heart failure’ may sound alarming and many patients fear it means that their heart is about to stop working. It’s actually a term that describes a situation where the heart cannot always pump enough blood around to keep up with all of the body’s needs.

In part one of a double series of articles, leading cardiologist Dr Peter Clarkson explains more about heart failure and the causes behind it.

Top half of smartly-dressed woman's torso, holding her hands to her chest


What’s the link between heart failure and heart disease?

Many, though not all causes of heart failure are due to disease of the heart muscle itself. These are loosely grouped under the term ‘cardiomyopathies’.

Most commonly, this will be a weakness of the pumping power of the heart due to loss of active heart muscle. For example, heart muscle can die off during a large heart attack or it can be destroyed by inflammation (myocarditis) or inherited genetic conditions. This situation is often characterised by doctors as ‘systolic’ heart failure, since ‘systole’ refers to the period of time where the heart contracts and ejects blood to the rest of the body.

Heart failure can also be caused by conditions where there is a normal, or even increased amount of heart muscle but the muscle has become stiff. Here the pumping power of the heart is fine but it is unable to relax properly between beats, which it needs to do to properly fill with blood before the next contraction. The result is that less blood is available to be pumped out with each beat. This is classified as “diastolic” heart failure, as “diastole” refers to the period of time where the heart fills with blood between beats.


What are the symptoms of heart failure?

The principal symptom of heart failure is shortness of breath with exertion. The more severe the heart failure is the less exertion is required to bring on breathing difficulty. Other associated symptoms are fatigue, lethargy and sometimes faintness, particularly if there is low blood pressure.

The term ‘congestive heart failure’ is sometimes used by doctors, as in some patients a back-up of blood within the vessels leads to a pressure build up which in turn causes fluid to leak out into the lungs (‘congestion’) and around the ankles and lower legs where it results in swelling (‘oedema). This accumulation of fluid can also be seen as rapid and unexplained weight gain.


Less common symptoms include:

  • A persistent cough and/or wheezing, which may be worse at night
  • Having to sleep propped up on more than two pillows in order to breathe comfortably, or waking up short of breath in the early hours
  • A bloated tummy
  • A fast, pounding heart rate, fluttering or irregular heartbeat (palpitations)


What causes heart failure?

There are various underlying causes but most commonly it is a chronic condition where the heart’s maximum pumping power has become impaired either due to a weakness or a stiffness of the heart muscle. The most common underlying causes are:


  • Disease of the heart valves

Severely narrowed or leaky heart valves can put excess strain on the heart, eventually leading to heart failure if not corrected.

  • Disease or inflammation of the heart muscle

Heart muscle disease (cardiomyopathy) changes the structure of the heart. The muscle may thicken and become stiffer, or the heart may dilate and contract more weakly. These conditions may be genetic in some case. Myocarditis is an acute inflammation of heart muscle, usually caused by a viral infection. This may result in a dilatation and weakening of the heart muscle so that it doesn't pump effectively.

This results in the heart muscle becoming thicker and therefore stiffer. In extreme cases the heart can fail due to having to pump against too high a pressure for too long.

  • Congenital heart defects

If the heart and its chambers or valves haven't formed correctly at birth, the heart has to work harder to pump blood through the heart and its nearby blood vessels, which may then lead to heart failure.

Abnormal heart rhythms can cause the heart to beat too fast or too slow. These both create extra work for the heart and so can lead to heart failure.

A common cause of coronary artery disease and also a cause of blockages of the microscopic arteries that allow blood to spread within the heart muscle cells (‘microvascular disease’).

  • Obesity

Which elevates the bodies demand for blood as well as being a common cause of many of the above illnesses.

  • Alcohol/drug abuse

Some recreational drugs, including an excess of alcohol, can be directly toxic to heart muscle.


To continue reading Dr Clarkson's double series of articles about heart failure, you can find part 2 here, where he explores diagnosing and treating heart failure.


Do you experience difficulty breathing, heart flutters and other symptoms of heart failure? Visit Dr Clarkson’s Top Doctors profile here to have your symptoms diagnosed.

By Dr Peter Clarkson

Dr Peter Clarkson is a leading consultant cardiologist and physician with extensive experience in general cardiology, interventional cardiology, pacing, and general internal medicine

He qualified from the University of London in 1988 and is a Director of The Surrey Cardiovascular Clinics. Furthermore, he holds an Honorary Contract at St George's Hospital, Tooting, and is the lead Cardiologist at Frimley Health NHS Foundation Trust.  Dr Clarkson has private practicing privileges at Spire Clare Park Hospital.

His established services include transoesophageal echocardiography, complex pacing and ICDs, diagnostic angiography as well as coronary intervention.

More recently, Dr Clarkson has established services such as Rapid Access Chest Pain Clinic, as well coronary intervention including angioplasty and stenting at the Catheter Lab at Frimley Park Hospital.

View Profile

Overall assessment of their patients

  • Related procedures
  • Heart attack
    Hypertension (high blood pressure)
    Heart failure
    Injury valves
    Heart murmur
    Ambulatory electrocardiogram (Holter)
    This website uses our own and third-party Cookies to compile information with the aim of improving our services, to show you advertising related to your preferences as well analysing your browsing habits. You can change your settings HERE.