Can you recognize a heart failure in the EKG?
introduction
Heart failure or heart failure is one of the most common internal diseases worldwide. It describes the inability of the heart to pump enough blood around the body to supply oxygen. Ultrasound and an X-ray provide diagnostic evidence of a weak heart. But changes typical of the heart failure can also be seen in the ECG.
Heart failure can be classified and differentiated according to various parameters. Usually, a distinction is first made according to the affected part of the heart, i.e. whether there is a right, a left heart or a global insufficiency (entire heart). Depending on the location, there are specific changes in the ECG. A further distinction can be made between a compensated or a decompensated cardiac insufficiency and whether it is a cardiac insufficiency with reduced performance or simply with a need that the heart can no longer meet due to its functional weakness.
causes
Typical causes of right heart failure are Pressure changes in the small pulmonary circulation. For example, if one or more of them become blocked Pulmonary arteryn, the pressure in the pulmonary circulation increases many times over. The right heart has to fight against this sudden very high pressure in order to continue to pump enough blood into the lungs. Usually the right heart does not succeed in this, so that it leads to pronounced heart failure Right heart failure comes. These changes lead to clear signs in the EKG, which are also called "Right heart hypertrophy signs"Are designated. Other causes of right heart weakness are irregular heartbeat or defects in the pulmonary valve. Typical causes for a Left heart failure would be Valve defects (Aortic valve, mitral valve), cardiac arrhythmias or a permanently much too high blood pressure. These causes and changes would also be seen in the EKG.
Symptoms of heart failure
Heart failure manifests itself primarily through an increasing intolerance to stress. This can manifest itself in rapid fatigue and shortness of breath. In addition, there is massive water retention in the case of a right heart failure, especially on the legs, dry cough, congested neck veins and digestive problems such as nausea, a feeling of fullness and liver pain.
Also read the article on the topic: Why does a cough occur when the heart is weak?
Diagnosis
Heart failure can usually already be determined through a detailed medical interview (the so-called anamnesis) and a physical examination. In the laboratory there are special markers (including BNP and NT-proBNP) that the doctor can determine and that confirm the suspicion of heart failure. The diagnosis of a weak heart can be confirmed by a heart echo (= ultrasound from the heart).In the ultrasound one would see massively enlarged heart chambers and atria, a restriction of the chamber movement as well as possible defects in the heart valves, which under certain circumstances represent the cause of the heart failure.
Another way to prove heart failure is to use an EKG. The EKG, also known as the electrocardiogram, provides information about the activity of the heart muscle by recording electrical potential fluctuations in the heart muscle cells. Different leads are used for this (I, II, III according to Einthoven, aVF, aVL and aVR according to Goldberger, as well as the chest wall leads V1-V6). The rashes in the EKG correspond to the spread of excitation in the individual heart structures.
The P wave (the first rash) symbolizes the spread of excitation in the atria, the PQ segment the spread of excitation from the atrium to the ventricle, the QRS complex symbolizes the spread of excitation in the ventricles and the T wave that follows at the end the discharge (Repolarization) of the ventricles.
In this way, statements about the type of position of the heart, the rhythm and its frequency can be made with the help of the EKG. If there are changes, one can then infer various diseases. For example, a type of position that was previously “normal”, for example an indifference type, and is now a right type or over-turned right type in the ECG, can be a sign of a right heart failure.
A new left-hand type or an over-turned left-hand type is always a sign of an acute left heart strain (for example a weakness of the left heart) or a heart attack. With the help of the QRS complex, which represents the heart chambers, statements can also be made about possible cardiac insufficiency.
The amplitudes of the R and S waves in the ECG would increase. This relationship is represented in an equation with the help of the so-called Sokolov-Lyon index. For left heart disease or left heart enlargement, the index would be greater than / equal to 3.5 mV.
In healthy people, the value would be less than 3.5. For right heart enlargement and right heart failure, the index would be greater than or equal to 1.05 mV. Another indication of cardiac insufficiency on the EKG would be a change in the T wave, i.e. the regression of excitation. This can then manifest itself in a negative (downward pointing) T-wave. If the atrium is enlarged as a sign of cardiac insufficiency, a bimodal P wave would result.
Find out more about the topic: These tests are done if you have heart failure
How does the EKG change with heart failure?
Heart failure can have a wide variety of causes and thus also a wide variety of manifestations in the ECG. Often the term weakness is equated with the term heart failure. A condition in which the heart cannot continue to pump the blood to the extent necessary, so that “blood backlogs” can occur.
The causes can, for example, be a disturbed transmission of stimuli in the heart. This would show up in an irregular rhythm.
If the transmission of stimuli within the heart does not work properly, it is called a bundle branch block. This manifests itself in the ECG, for example, by means of an extended PQ time.
Another possibility would be an unphysiological enlargement of the heart. In this case the derivative with the greatest amplitude would deviate from the normal state. Instead of the second derivative, the amplitude would be greatest in the fourth derivative, for example.
A heart attack or inflammation of the heart muscle, known as myocarditis, can also cause heart failure and can be seen in the ECG. In these cases the amplitudes of the leads diverge from the amplitudes of a person with healthy heart.
In addition, there are also discrepancies within the excitation complexes compared to those with healthy hearts. A typical sign of an anterior cardiac infarction is, for example, an insufficient depression between the S and T waves of the excitation complex.
Exercise ECG for heart failure
The stress ECG is a frequently used examination technique, which is particularly useful in the case of high blood pressure, a coronary heart disease (CHD) or cardiac arrhythmia is used. Cardiovascular diseases can be diagnosed by stressing the body. The exercise ECG is usually performed on a bicycle or a treadmill and measures the performance that the patient achieves at a maximum heart rate of 220 or certain blood gas values. While cycling, an ECG is written in parallel, which the doctor evaluates on a connected monitor. Criteria for terminating an exercise ECG are signs of reduced blood flow to the heart (Myocardial ischemia), which can be seen in the ECG as ST depression or elevation or in severe chest pain radiating to the left arm, critical blood pressure or cardiac arrhythmia.
Please also read our page Exercise ECG.
Long-term ECG for heart failure
A long-term ECG is mainly performed in patients with (temporary) cardiac arrhythmias and / or unclear dizziness and unconsciousness (syncope). For this purpose, the patient receives a portable recorder that is attached for 24 to 48 hours and continuously records ECGs over this period. Due to the long period of time, the probability is high that you will also pick up the cardiac arrhythmia.
Since some cardiac arrhythmias only occur during stress, e.g. In the case of heavy lifting, it is important that the patient keeps a diary of what activities he was doing when the cardiac arrhythmia occurred (e.g. whether he was sleeping or exercising) and what medication he was taking.
Read more on the subject at: Long-term ECG
Exercise ECG for heart failure
In order to avoid serious complications such as ventricular fibrillation during a heart attack, a defibrillator must always be close at hand during the stress ECG. Absolute contraindications, i.e. prohibitions for carrying out this examination, are a heart attack that has already occurred or unstable angina pectoris. With the help of an exercise ECG, among other things the severity of heart failure can also be assessed.
This would show whether the symptoms (e.g. shortness of breath) only occur under very high loads or even under very light ones. In the course of heart failure, cardiac arrhythmias can always occur, which can be diagnosed using the stress ECG. Arrhythmias are always associated with an increased risk of sudden cardiac death.
