The cardiac cycle Cycle The type of signal that ends the inspiratory phase delivered by the ventilator Invasive Mechanical Ventilation describes 1 complete contraction and relaxation of all 4 chambers of the heart during a standard heartbeat. The cardiac cycle Cycle The type of signal that ends the inspiratory phase delivered by the ventilator Invasive Mechanical Ventilation includes 7 phases, which together describe the cycle Cycle The type of signal that ends the inspiratory phase delivered by the ventilator Invasive Mechanical Ventilation of ventricular filling, isovolumetric contraction, ventricular ejection, and isovolumetric relaxation. The cycle Cycle The type of signal that ends the inspiratory phase delivered by the ventilator Invasive Mechanical Ventilation is frequently represented in a graph known as a pressure-volume loop, which shows how intraventricular volumes and pressures are related to one another throughout the cardiac cycle Cycle The type of signal that ends the inspiratory phase delivered by the ventilator Invasive Mechanical Ventilation.
Last updated: 22 Jun, 2022
The cardiac cycle Cycle The type of signal that ends the inspiratory phase delivered by the ventilator Invasive Mechanical Ventilation describes 1 complete contraction and relaxation of all 4 chambers of the heart during a standard heartbeat. The 7 phases of the cardiac cycle Cycle The type of signal that ends the inspiratory phase delivered by the ventilator Invasive Mechanical Ventilation all occur in < 1 second.
Ventricular systole and diastole, and the coinciding phases of the cardiac cycle Cycle The type of signal that ends the inspiratory phase delivered by the ventilator Invasive Mechanical Ventilation
Image by Lecturio.Blood sequentially flows through the heart in 1 direction through the following structures:
The general structure and
flow
Flow
Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls.
Vascular Resistance, Flow, and Mean Arterial Pressure of blood through the heart:
Blue areas represent deoxygenated blood, which passes through the right side of the heart. Red areas represent oxygenated blood, which passes through the left side of the heart. The right side of the heart pumps the deoxygenated blood to the
lungs
Lungs
Lungs are the main organs of the respiratory system. Lungs are paired viscera located in the thoracic cavity and are composed of spongy tissue. The primary function of the lungs is to oxygenate blood and eliminate CO2.
Lungs: Anatomy. The left side of the heart pumps blood out to the systemic arterial system.
Ventricular filling occurs in 3 parts:
Diagram of the cardiac
cycle
Cycle
The type of signal that ends the inspiratory phase delivered by the ventilator
Invasive Mechanical Ventilation highlighting phases 6 and 7, ventricular filling:
As the left ventricle (LV) remains relaxed, the left ventricular pressure is less than the pressure in the left atrium (LA). The pressure differential opens the
mitral valve
Mitral valve
The valve between the left atrium and left ventricle of the heart.
Heart: Anatomy and blood begins flowing from the LA into the LV, passively filling the LV. During this time, the left ventricular pressure remains low (red line), but the volume increases (blue line), representing a period of isoelectric activity on the
electrocardiogram
Electrocardiogram
An electrocardiogram (ECG) is a graphic representation of the electrical activity of the heart plotted against time. Adhesive electrodes are affixed to the skin surface allowing measurement of cardiac impulses from many angles. The ECG provides 3-dimensional information about the conduction system of the heart, the myocardium, and other cardiac structures.
Electrocardiogram (ECG) (yellow line).
Diagram of the cardiac
cycle
Cycle
The type of signal that ends the inspiratory phase delivered by the ventilator
Invasive Mechanical Ventilation highlighting
phase 1
Phase 1
Skin: Structure and Functions, the active filling phase of the left ventricle (LV):
Atrial pressure (dotted squares) and left ventricular pressure (red line) only slightly increase during atrial systole. Atrial
depolarization
Depolarization
Membrane Potential is represented by the
P wave
P wave
Electrocardiogram (ECG) on the
electrocardiogram
Electrocardiogram
An electrocardiogram (ECG) is a graphic representation of the electrical activity of the heart plotted against time. Adhesive electrodes are affixed to the skin surface allowing measurement of cardiac impulses from many angles. The ECG provides 3-dimensional information about the conduction system of the heart, the myocardium, and other cardiac structures.
Electrocardiogram (ECG) (yellow line). Atrial systole occurs immediately thereafter.
Isovolumetric means “same volume”. Phase 2 Phase 2 Skin: Structure and Functions represents ventricular contraction while both the AV valves and the semilunar valves are closed, which = no change in ventricular volume.
Diagram of the cardiac
cycle
Cycle
The type of signal that ends the inspiratory phase delivered by the ventilator
Invasive Mechanical Ventilation highlighting
phase 2
Phase 2
Skin: Structure and Functions, isovolumetric contraction:
Left ventricular volume (blue) remains the same, but the left ventricular pressure (red) sharply increases, occurring immediately following left ventricular
depolarization
Depolarization
Membrane Potential (seen as the
QRS complex
QRS complex
Electrocardiogram (ECG) on the
ECG
ECG
An electrocardiogram (ECG) is a graphic representation of the electrical activity of the heart plotted against time. Adhesive electrodes are affixed to the skin surface allowing measurement of cardiac impulses from many angles. The ECG provides 3-dimensional information about the conduction system of the heart, the myocardium, and other cardiac structures.
Electrocardiogram (ECG) (yellow line)).
Diagram of the cardiac
cycle
Cycle
The type of signal that ends the inspiratory phase delivered by the ventilator
Invasive Mechanical Ventilation highlighting phases 3 and 4, ventricular ejection:
As the left ventricle remains contracted, the ventricular pressure (red line) peaks and begins to decrease as blood is ejected out of the ventricle. The phase coincides with the
ST segment
ST segment
Isoelectric segment between the s wave and the initial deflection of the t wave.
Electrocardiogram (ECG) of the
electrocardiogram
Electrocardiogram
An electrocardiogram (ECG) is a graphic representation of the electrical activity of the heart plotted against time. Adhesive electrodes are affixed to the skin surface allowing measurement of cardiac impulses from many angles. The ECG provides 3-dimensional information about the conduction system of the heart, the myocardium, and other cardiac structures.
Electrocardiogram (ECG) followed by the
T wave
T wave
Electrocardiogram (ECG) of ventricular
repolarization
Repolarization
Membrane Potential (yellow line).
Diagram of the cardiac
cycle
Cycle
The type of signal that ends the inspiratory phase delivered by the ventilator
Invasive Mechanical Ventilation highlighting phase 5, isovolumetric relaxation:
As the left ventricle begins isovolumetric relaxation, the ventricular pressure sharply drops (red line), but the volume does not change (blue line). The
aortic valve
Aortic valve
The valve between the left ventricle and the ascending aorta which prevents backflow into the left ventricle.
Heart: Anatomy closes in response to the pressure differential between the
aorta
Aorta
The main trunk of the systemic arteries.
Mediastinum and Great Vessels: Anatomy and the left ventricle.
Aortic pressure
Aortic pressure
Cardiac Mechanics is shown by the top dotted line. The ventricle finishes repolarizing as shown on the
electrocardiogram
Electrocardiogram
An electrocardiogram (ECG) is a graphic representation of the electrical activity of the heart plotted against time. Adhesive electrodes are affixed to the skin surface allowing measurement of cardiac impulses from many angles. The ECG provides 3-dimensional information about the conduction system of the heart, the myocardium, and other cardiac structures.
Electrocardiogram (ECG) (yellow line).
Diagram of the cardiac
cycle
Cycle
The type of signal that ends the inspiratory phase delivered by the ventilator
Invasive Mechanical Ventilation highlighting the phases of atrial diastole:
Atrial pressure is shown by the lower dotted line. The A wave indicates the increase in atrial pressure during atrial contraction. As the ventricles contract against the closed atrioventricular (AV) valves, the increase in pressure reverberates through the atria as seen in the C wave. The C wave coincides with the isovolumetric contraction of the left ventricle. Atrial relaxation begins during ventricular systole. With the AV valves closed, the atria are passively filled, increasing the atrial pressure. The V wave signifies the sudden fall in atrial pressure when the AV valves open to begin phase 6 (passive ventricular filling).
The normal pressures found in the heart chambers and great vessels during ventricular systole and diastole are shown in the table and image below:
Location | Pressure during ventricular systole ( mm MM Multiple myeloma (MM) is a malignant condition of plasma cells (activated B lymphocytes) primarily seen in the elderly. Monoclonal proliferation of plasma cells results in cytokine-driven osteoclastic activity and excessive secretion of IgG antibodies. Multiple Myeloma Hg) | Pressure during ventricular diastole ( mm MM Multiple myeloma (MM) is a malignant condition of plasma cells (activated B lymphocytes) primarily seen in the elderly. Monoclonal proliferation of plasma cells results in cytokine-driven osteoclastic activity and excessive secretion of IgG antibodies. Multiple Myeloma Hg) |
---|---|---|
Right atrium | 0–4 | 0–4 |
Right ventricle | 25 | 4 |
Pulmonary arteries Arteries Arteries are tubular collections of cells that transport oxygenated blood and nutrients from the heart to the tissues of the body. The blood passes through the arteries in order of decreasing luminal diameter, starting in the largest artery (the aorta) and ending in the small arterioles. Arteries are classified into 3 types: large elastic arteries, medium muscular arteries, and small arteries and arterioles. Arteries: Histology | 25 | 10 |
Left atrium | 8–10 | 8–10 |
Left ventricle | 120 | 10 |
Aorta Aorta The main trunk of the systemic arteries. Mediastinum and Great Vessels: Anatomy | 120 | 80 |
Pressures (in
mm
MM
Multiple myeloma (MM) is a malignant condition of plasma cells (activated B lymphocytes) primarily seen in the elderly. Monoclonal proliferation of plasma cells results in cytokine-driven osteoclastic activity and excessive secretion of IgG antibodies.
Multiple Myeloma Hg) within the chambers of the heart and great vessels:
The numerator represents the highest pressure achieved during systole and the denominator represents the lowest pressure achieved during diastole. Pressure differentials directly cause valve opening and blood movement.
A:
aorta
Aorta
The main trunk of the systemic arteries.
Mediastinum and Great Vessels: Anatomy
RA: right atrium
PT:
pulmonary trunk
Pulmonary Trunk
Truncus Arteriosus
LA: left atrium
RV: right ventricle
LV: left ventricle
* denotes end-diastolic pressure
Left ventricular pressure-volume loop:
The diagram illustrates the
relationship
Relationship
A connection, association, or involvement between 2 or more parties.
Clinician–Patient Relationship between left intraventricular pressure and volume throughout the cardiac
cycle
Cycle
The type of signal that ends the inspiratory phase delivered by the ventilator
Invasive Mechanical Ventilation. The segment from point A to point B represents ventricular filling. The
mitral valve
Mitral valve
The valve between the left atrium and left ventricle of the heart.
Heart: Anatomy opens at point A and closes at point B. The segment from point B to point C represents isovolumetric contraction. The
aortic valve
Aortic valve
The valve between the left ventricle and the ascending aorta which prevents backflow into the left ventricle.
Heart: Anatomy opens at point C. The curved line from point C to point D represents ventricular ejection. The
aortic valve
Aortic valve
The valve between the left ventricle and the ascending aorta which prevents backflow into the left ventricle.
Heart: Anatomy closes at point D. The segment from point D to point A represents isovolumetric relaxation.
The following are common conditions affecting the cardiac cycle Cycle The type of signal that ends the inspiratory phase delivered by the ventilator Invasive Mechanical Ventilation.