Question

What is the relationship between the Cardiac Cycle and an ECG?

Answer 1

The cardiac cycle describes the human heart's activity from the start of one heartbeat to the start of the next. It is divided into two parts: diastole, when the heart muscle relaxes and refills with blood, and systole, when the heart muscle contracts and pumps blood vigorously.
The cardiac cycle is divided into two phases: systole (contraction phase) and diastole (relaxation phase) (the relaxation phase). Each of them is subsequently subdivided into two parts: atrial and ventricular.
The top number on your reading is your systolic blood pressure.

Complete explanation:
The electrocardiogram, or ECG, is a graphical representation of the heart's electrical activity during the cardiac cycle. Each ECG peak is represented by a letter from P to T:
P-wave – atrial depolarization or atrial contraction.
Depolarization of the ventricles or ventricular contraction is the QRS complex.
T-wave – ventricular repolarization.
Atrial depolarization causes the P wave. The QRS complex is formed by ventricular depolarization and signals the beginning of ventricular contraction. The T wave is the outcome of ventricular repolarization and marks the start of ventricular relaxation.
Phases of Cardiac Cycle:
1. Atrial contraction (First Phase)
2. Isovolumetric Contraction (Second Phase)
3. Rapid Ventricular Ejection (Third Phase)
4. Slow Ventricular Ejection (Fourth Phase)
5. Isovolumetric Relaxation (Fifth Phase)
6. Rapid Passive Ventricular Filling (Sixth Phase)

Note:
The size and position of the chambers, the presence of cardiac disease, and the effects of medication or devices used to regulate the heart, such as a pacemaker, are all measured with an ECG.
The ECG gadget detects and amplifies the minute electrical changes on the skin that occur as the heart muscle depolarizes after each heartbeat, then converts the heart's electrical pulses into a visual representation.
A P wave (atrial depolarization), a QRS complex (ventricular depolarization), and a T wave make up a typical ECG trace of the cardiac cycle (heartbeat) (ventricular repolarization). The U wave (Purkinje repolarization) is a second wave that is often detectable but not always.
During a myocardial infarction, the ST complex is frequently raised.
When the P wave is missing, atrial fibrillation develops, indicating irregular, fast, and inefficient atrial contraction. However, atrial fibrillation is rarely lethal on its own.
Ventricular fibrillation is characterised by the absence of all normal waves on an ECG, rapid and irregular heartbeats, and sudden cardiac death.