Arrhythmias
First degree heart block
First degree heart block is common, and it can affect anyone at any age. It describes a delay in the electrical signal as it travels from the upper chambers of the heart to the lower chambers, rather than a true blockage. Every signal still gets through, which is why many people notice nothing at all and why the condition is usually diagnosed when testing is being done for something else.
What first degree heart block is
Despite how the name sounds, heart block does not mean the heart has stopped working. It refers to a problem with the electrical signals that control how the heart beats, not to a narrowing or blockage in the arteries. Dr Jogiya often draws this distinction early in a consultation, because it changes how patients understand both the condition and the treatments that are used for it.
A heart block refers to a delay to the conduction system in the heart, usually in the AV (atrioventricular) node. This node controls the synchronisation of beats being delivered from the atria to the ventricles. In first degree heart block that delay is mild. The impulse is slowed on its way through the AV node, but it still reaches the ventricles, so the heart keeps a coordinated rhythm.
Of the three degrees of heart block, first degree is the least serious. It is common for it to occur at night time, and it is usually diagnosed when testing for an unrelated condition. Some people can still have very minor symptoms during the day.
What happens in the heart's electrical system
Every heartbeat begins with an electrical signal generated in a small area of the heart called the sinus node. That signal spreads across the upper chambers, known as the atria, before passing through a specialised structure called the atrioventricular node, usually shortened to the AV node. From there the impulse travels on to the lower chambers, known as the ventricles, which pump blood around the body.
When electrical signals are slowed or interrupted as they travel from the atria to the ventricles, heart block occurs. In the first degree form the signals are slowed through the AV node but still reach the ventricles, so the coordination between the upper and lower chambers is preserved.
Heart blocks can occur for a number of different reasons, and understanding the underlying cause helps guide treatment and shows whether the condition is likely to progress. In some people the heart's electrical system simply changes naturally with age. Other recognised causes include the following.
- Certain medications that influence heart rhythm
- Previous heart attacks
- Coronary artery disease
- Infections or inflammation affecting the heart muscle
- Congenital heart conditions present from birth
- No clear cause identified, which is not unusual
The symptoms people notice
Many people with first degree heart block have no symptoms at all. Because every signal still reaches the ventricles, the heart rate and rhythm usually stay normal, and the delay itself is not usually something you can feel. Where symptoms do appear in this form, they tend to be very minor.
Where heart block does cause symptoms, they generally relate to the heart beating more slowly than the body needs, so that not enough blood and oxygen is delivered during certain activities. The symptoms listed below are those described for heart block as a whole. They are not a list of what first degree heart block causes, and they are far more typical of the more significant forms.
If you notice any of them, it is worth being assessed properly rather than assuming a known first degree delay is the explanation. Any persistent dizziness or unexplained fainting should always be assessed by a medical professional.
- Fatigue or reduced energy
- Dizziness or light-headedness
- Shortness of breath during activity
- Episodes of fainting
How first degree heart block is diagnosed
First degree heart block is diagnosed by examining the heart's electrical activity. The standard test is a 12 lead ECG, which records the electrical signals of the heart and can show whether they are being delayed on their way from the atria to the ventricles.
Because there are often no symptoms to prompt a test, most people learn they have this delay after an ECG that was arranged for an entirely different reason.
If symptoms come and go, or the picture is not clear on a resting trace, Dr Jogiya may arrange a longer recording. An ECG monitor worn for 24 hours or more captures the heart rhythm across an ordinary day and night, which matters here because first degree heart block is common at night time.
An echocardiogram may also be used to assess the structure and function of the heart, particularly where an underlying cause is being looked for. Regular ECGs are then used over time to check that the picture remains stable and that any treatment is working as it should.
How first degree heart block is treated
Treatment options depend on the type of heart block you are diagnosed with and the degree to which any symptoms affect your quality of life. For patients without symptoms, first degree heart block does not require treatment. What it does need is an accurate diagnosis and, where appropriate, monitoring so that any change is picked up early.
For those who do have symptoms, medical management is the main treatment method. That normally begins with understanding the underlying cause, which can include reviewing any medicines that influence heart rhythm and treating conditions such as a previous heart attack or an infection affecting the heart. Any change to prescribed medication is a decision for the doctor who prescribed it, so nothing should be stopped or altered on the strength of a web page.
A pacemaker is not the usual treatment for this form. Pacemakers are generally reserved for the more significant types of heart block, where signals are dropped or fail to reach the ventricles at all, and where a device is needed to restore a reliable rhythm.
Even where no treatment is required, everyday habits continue to play an important role in overall cardiovascular health. Regular physical activity, balanced nutrition and effective stress management all support heart function. Steady, sustainable routines tend to make more difference over time than drastic changes.
When to seek help
First degree heart block is not an emergency, and finding it on an ECG is not in itself a reason for alarm. It is still worth having it explained properly, so the type of block is confirmed and anything more significant is ruled out.
Arrange an assessment with Dr Jogiya if you have been told you have a conduction delay and want to understand what it means, if you have new fatigue, dizziness or breathlessness on activity, or if you have fainted without a clear explanation.
Call 999 if you have chest pain that does not settle, if someone collapses and does not come round, or if someone becomes unresponsive or stops breathing. Those situations need emergency assessment rather than a routine appointment.
More in arrhythmias
Related conditions he treats.
- Atrial fibrillationAtrial fibrillation, commonly known as AF, is a condition where the atria, or upper chambers of the heart, fire chaotic electrical impulses. This leads the muscle to quiver, or fibrillate, instead of beat, so the heartbeat becomes irregular and is often faster than normal. It is one of the most common heart rhythm issues and around 1.7 million people in the UK have been diagnosed with it.
- Atrial flutterAtrial flutter is a heart rhythm problem that affects the upper chambers of the heart, known as the atria. Instead of beating at a normal pace, the atria beat rapidly, but in a regular and organised pattern rather than a chaotic one. Because the chambers do not have enough time to fill properly, blood is not pumped efficiently from the top chambers to the bottom chambers, which is what leads to shortness of breath.
- Atrial tachycardiaAtrial tachycardia is a fast heart rhythm that starts in the atria, the two upper chambers of the heart. An electrical signal emerges from another section of the atria and causes a rapid repeating beat, which means the atria beat very fast. It is one form of supraventricular tachycardia, or SVT, and short bouts of it can be common.
- Bundle branch blockBundle branch block describes a block in the part of the heart's conduction system known as the bundle branches. These branches carry the electrical impulse from the AV node down to each ventricle, and when one of them is blocked the signal reaches one side of the heart before the other, so the two ventricles no longer contract in step. It is a pattern picked up on an ECG, and mostly it is something monitored rather than actively treated.
- Second degree heart blockSecond degree heart block is a fault in the heart's electrical wiring, not a blockage in an artery. Some of the electrical signals travelling from the upper chambers of the heart fail to reach the lower chambers, so a heartbeat is occasionally missed. There are two types, known as Mobitz I and Mobitz II, and they are treated very differently.
- Sick sinus syndromeSick sinus syndrome, also called sinus node disease, is a condition where the sinus node, the small area of tissue that acts as the heart's own natural pacemaker, is not functioning properly. Sometimes the node will send an impulse as it should, and sometimes it may not fire an impulse at all, or the impulses may be out of sync. Some patients notice symptoms such as palpitations and shortness of breath, and because the node is unreliable rather than permanently stopped, those symptoms often come and go.
- Supraventricular tachycardiaSupraventricular tachycardia, usually shortened to SVT, is a fast heart rhythm that starts above the ventricles, in the upper part of the heart. Symptoms vary widely from one person to another, so some people are very aware of an episode while others barely notice one. Short bouts of SVT can be common, and can usually be treated very easily.
- Tachy brady syndromeTachy brady syndrome is a heart rhythm problem in which the heart rate increases and then decreases spontaneously, without any external influence. Instead of settling at a pace that matches what you are doing, the heart swings between periods of a slow rate and sudden bursts of a fast one. It is closely linked to sinus node disease, and it occurs mostly alongside atrial fibrillation.