Pressure Curves Flashcards
At what part of the cardiac cycle is ATRIAL SYSTOLE?
The end of diastole
What is happening with the heart during ATRIAL SYSTOLE?
Heart: Prior to atrial systole, blood has been flowing passively from the atrium into the ventricle through the open AV valve. During atrial systole the atrium contracts and tops off the volume in the ventricle with only a small amount of blood. Atrial contraction is complete before the ventricle begins to contract.
What is happening with the atrial pressure during ATRIAL SYSTOLE?
Atrial pressure: The “a” wave occurs when the atrium contracts, increasing atrial pressure (yellow). Blood arriving at the heart cannot enter the atrium so it flows back up the jugular vein, causing the first discernible wave in the jugular venous pulse. Atrial pressure drops when the atria stop contracting.
What is happening with the ECG during ATRIAL SYSTOLE?
ECG: An impulse arising from the SA node results in depolarization and contraction of the atria (the right atrium contracts slightly before the left atrium). The P wave is due to this atrial depolarization. The PR segment is electrically quiet as the depolarization proceeds to the AV node. This brief pause before contraction allows the ventricles to fill completely with blood.
At what part of the cardiac cycle is ISOVOLUMETRIC CONTRACTION?
The beginning of systole
What is happening with the heart during ISOVOLUMETRIC CONTRACTION?
Heart: The atrioventricular (AV) valves close at the beginning of this phase. Electrically, ventricular systole is defined as the interval between the QRS complex and the end of the T wave (the Q-T interval). Mechanically, the isovolumic phase of ventricular systole is defined as the interval between the closing of the AV valves and the opening of the semilunar valves (aortic and pulmonary valves).
What is happening with the pressure and volume wave during ISOVOLUMETRIC CONTRACTION?
Pressures & Volume: The AV valves close when the pressure in the ventricles (red) exceeds the pressure in the atria (yellow). As the ventricles contract isovolumetrically – their volume does not change (white) – the pressure inside increases, approaching the pressure in the aorta and pulmonary arteries (green).
What is happening with the ECG during ISOVOLUMETRIC CONTRACTION?
ECG: The electrical impulse propagates from the AV node through the His bundle and Purkinje system to allow the ventricles to contract from the apex of the heart towards the base. The QRS complex is due to ventricular depolarization, and it marks the beginning of ventricular systole. It is so large that it masks the underlying atrial repolarization signal.
What is happening with the heart during RAPID EJECTION?
Heart: The semilunar (aortic and pulmonary) valves open at the beginning of this phase of ventricular systole.
What is happening with the pressures and volume during RAPID EJECTION?
Pressures & Volume: While the ventricles continue contracting, the pressure in the ventricles (red) exceeds the pressure in the aorta and pulmonary arteries (green); the semilunar valves open, blood exits the ventricles, and the volume in the ventricles decreases rapidly (white). As more blood enters the arteries, pressure there builds until the flow of blood reaches a peak. The “c” wave of atrial pressure is not normally discernible in the jugular venous pulse. Right ventricular contraction pushes the tricuspid valve into the atrium and increases atrial pressure, creating a small wave into the jugular vein. It is normally simultaneous with the carotid pulse.
What is happening with the ECG during RAPID EJECTION?
between the s wave and the t wave
What part of the cardiac cycle is REDUCED EJECTION?
The end of systole
What is happening with the heart during REDUCED EJECTION?
Heart: At the end of this phase the semilunar (aortic and pulmonary) valves close.
What is happening with the pressures and volume during REDUCED EJECTION?
Pressures & Volume: After the peak in ventricular and arterial pressures (red and green), blood flow out of the ventricles decreases and ventricular volume decreases more slowly (white). When the pressure in the ventricles falls below the pressure in the arteries, blood in the arteries begins to flow back toward the ventricles and causes the semilunar valves to close. This marks the end of ventricular systole mechanically.
What is happening with the ECG during REDUCED EJECTION?
ECG: The T wave is due to ventricular repolarization. The end of the T wave marks the end of ventricular systole electrically.
What part of the cardiac cycle is ISOVOLUMETRIC RELAXATION?
The beginning of diastole
What is happening with the heart during ISOVOLUMETRIC RELAXATION?
Heart: At the beginning of this phase the AV valves are closed.
What is happening with the pressures and volume during ISOVOLUMETRIC RELAXATION?
Pressures & Volume: Throughout this and the previous two phases, the atrium in diastole has been filling with blood on top of the closed AV valve, causing atrial pressure to rise gradually (yellow). The “v” wave is due to the back flow of blood after it hits the closed AV valve. It is the second discernible wave of the jugular venous pulse. The pressure in the ventricles (red) continues to drop. Ventricular volume (white) is at a minimum and is ready to be filled again with blood.
What is happening with the ECG during ISOVOLUMETRIC RELAXATION?
At the end of the t wave
What is happening with the heart during RAPID VENTRICULAR FILLING?
Heart: Once the AV valves open, blood that has accumulated in the atria flows rapidly into the ventricles.
What is happening with the pressures and volume during RAPID VENTRICULAR FILLING?
Pressures & Volume: Ventricular volume (white) increases rapidly as blood flows from the atria into the ventricles.
What is happening with the ECG during RAPID VENTRICULAR FILLING?
It is after the T wave before the P wave
What part of the cardiac cycle is REDUCED VENTRICULAR FILLING?
DIASTASIS
What is happening with the pressures and volume during REDUCED VENTRICULAR FILLING?
Pressures & Volume: Ventricular volume (white) increases more slowly now. The ventricles continue to fill with blood until they are nearly full.
What is happening with the ECG during REDUCED VENTRICULAR FILLING?
ECG is before the next cycle
