B.11 Heart Cycle. Hemodynamic Evaluation Flashcards
B.11 Heart Cycle. Hemodynamic Evaluation
The Cardiac Cycle picture - draw it!
B.11 Heart Cycle. Hemodynamic Evaluation
The Cardiac Cycle picture defintion
The cardiac cycle can be divided into two phases: systole, in which blood is pumped from the heart, and diastole, in which the heart fills with blood. Systole and diastole are each subdivided into two further phases, resulting in a total of four phases of heart action. Depending on the phase, pressure and volume in the ventricles and atria change, with the pressure in the left ventricle changing the most and the pressure in the atria the least.
B.11 Heart Cycle. Hemodynamic Evaluation
How long is systole
0.27 s
stays relatively constant
systole is when Ventricular contraction and atrial relaxation and filling occur during this phase.
B.11 Heart Cycle. Hemodynamic Evaluation
what is the first phase in systole
Isovolumetric contraction occurs for 0.05 sec
B.11 Heart Cycle. Hemodynamic Evaluation
What happens during Isovolumetric contraction
Main function: ventricular contraction
Follows ventricular filling
Occurs in early systole, directly after the atrioventricular valves (AV valves) close and before the semilunar valves open (all valves are closed)
Ventricle contracts (i.e., pressure increases) with no corresponding ventricular volume change
LV pressure: 8 mm Hg → ∼ 80 mm Hg (when aortic and pulmonary valves open passively)
LV volume: remains ∼ 150 mL
RV pressure: 5 mm Hg → 25 mm Hg
RV volume: ∼ 150 mL [1]
The period of highest O2 consumption
B.11 Heart Cycle. Hemodynamic Evaluation
Keys in Isovolumetric contraction
Ventricles begin to contract, pressure rises rapidly
All valves closed
No volume change, just pressure build-up
S1 (“lub”) sound = closure of AV valves
B.11 Heart Cycle. Hemodynamic Evaluation
ECG Correlation of Isovolumetric contraction
Begins immediately after the QRS complex starts
QRS complex = ventricular depolarization
→ Triggers ventricular contraction
Isovolumetric contraction happens before the aortic/pulmonary valves open
→ So it corresponds to the early part of systole, right after QRS
B.11 Heart Cycle. Hemodynamic Evaluation
What is the second phase
Systolic ejection
occurs for 0.22 s
B.11 Heart Cycle. Hemodynamic Evaluation
What happens in Systolic ejection
Main function: Blood is pumped from the ventricles into the circulation and lungs.
Follows isovolumetric contraction
Occurs between the opening and closing of the aortic valve and pulmonary valve
Ventricles contract (i.e., pressure increases) to eject blood, which decreases the ventricular volume
Pressure: first increases from ∼ 80 mm Hg to 120 mm Hg and then decreases until aortic and pulmonary valves close
Volume: ejection of ∼ 90 mL SV (150 mL → 60 mL)
B.11 Heart Cycle. Hemodynamic Evaluation
Systolic ejection keys
Semilunar valves open
– Aortic and pulmonary valves
– Ventricular pressure > aortic/pulmonary pressure
Blood is ejected from ventricles
– ~70 mL stroke volume
– Rapid ejection followed by reduced (slower) ejection
Aortic and pulmonary pressures rise
– As blood is pushed out, pressure increases in arteries
Left ventricular pressure starts falling
– As muscle relaxes near the end of ejection
Semilunar valves close at the end
– When aortic/pulmonary pressure > ventricular pressure
– This marks the beginning of isovolumetric relaxation
– S2 heart sound is produced
B.11 Heart Cycle. Hemodynamic Evaluation
ECG Correlation Systolic ejection
Begins mid-to-late QRS complex
→ QRS = ventricular depolarization → triggers contraction
Systolic ejection starts once ventricular pressure > arterial pressure
→ So it starts during QRS, not immediately at the beginning
Continues through the ST segment
Ends near the end of the T wave (ventricular repolarization)
ST segment reflects the period when ventricular contraction is ongoing
T wave marks end of ejection and onset of isovolumetric relaxation
B.11 Heart Cycle. Hemodynamic Evaluation
What is Diastole
0.53 sec
can become longer
A phase of the cardiac cycle that follows systole and the S2 heart sound. Ventricular filling occurs during this phase due to atrial contraction and ventricular relaxation.
B.11 Heart Cycle. Hemodynamic Evaluation
What phases occur in diastole
isovolumetric relaxation - 0.08 sec
ventricular filling
B.11 Heart Cycle. Hemodynamic Evaluation
isovolumetric relaxation
Main function: ventricular relaxation
Follows systolic ejection
Occurs between aortic valve closing and mitral valve opening
All valves closed (volume remains constant) Dicrotic notch: slight increase of aortic pressure in the early diastole that corresponds to closure of the aortic valve
The ventricles relax (i.e., pressure decreases) with no corresponding ventricular volume change until ventricular pressure is lower than atrial pressure and atrioventricular valves open
Pressure: decreases to ∼ 10 mm Hg in the left ventricle and ∼ 5 mm Hg in the right ventricle
Volume: remains at ∼ 60 mL
Coronary blood flow peaks during early diastole at the point when the pressure differential between the aorta and the ventricle is the greatest.
The coronary arteries fill with blood during diastole because they are compressed during ventricular systole.
B.11 Heart Cycle. Hemodynamic Evaluation
keys to Isovolumetric relaxation
Isovolumetric relaxation is the early part of diastole, immediately after ventricular systole ends, when the ventricles relax but all four valves are closed, so no blood flows in or out.
Semilunar valves close (aortic & pulmonary)
→ When arterial pressure exceeds falling ventricular pressure
→ Closure produces S2 heart sound (“dub”)
🚫 AV valves still closed (mitral & tricuspid)
→ Ventricular pressure still > atrial pressure
📉 Ventricular pressure falls rapidly
→ Due to active myocardial relaxation (energy-dependent process)
🧪 No change in ventricular volume
→ That’s why it’s called “isovolumetric” (same volume)
🫁 No blood enters or exits ventricles
B.11 Heart Cycle. Hemodynamic Evaluation
isovolumetric relaxation ECG correlation
Starts at the end of the T wave
→ T wave = ventricular repolarization
Isovolumetric relaxation occurs immediately after repolarization ends
Ends just before the next P wave, when ventricular pressure falls below atrial pressure and AV valves open
B.11 Heart Cycle. Hemodynamic Evaluation
What is the second phase of diastole
ventricular filling - 0.53 sec
B.11 Heart Cycle. Hemodynamic Evaluation
ventricular filling
Main function: ventricles fill with blood
Rapid filling - passive filling of 80%
Follows isovolumetric relaxation
Occurs in early diastole; immediately after mitral valve opening
Blood flows passively from the atria to the ventricles. The largest volume of ventricular filling occurs during this phase.
Reduced filling
Follows rapid filling - atrial systole filling, remaining 20%
Occurs in late diastole; immediately before atrioventricular valves close
LV pressure: ∼ 8 mm Hg; RV pressure: ∼ 5 mm Hg (2–8 mm Hg)
LV and RV volume: ventricles fill with ∼ 90 mL (60 mL → 150 mL)
B.11 Heart Cycle. Hemodynamic Evaluation
ventricular filling keys
Ventricular filling is the diastolic phase during which blood flows from the atria into the relaxed ventricles. It begins when AV valves open (mitral/tricuspid) after isovolumetric relaxation ends.
Key Features:
Starts when ventricular pressure < atrial pressure
→ This opens AV valves (mitral and tricuspid)
Occurs in 3 stages:
Rapid passive filling (70–80%)
* Blood flows quickly from atria to ventricles
* Responsible for S3 if abnormal (e.g. in heart failure)
Diastasis (slow filling)
* Pressure starts to equalize between atria and ventricles
* Minimal flow
Atrial contraction (atrial systole / "atrial kick")
* Contributes final 20–30% of ventricular filling
* S4 may be heard in stiff ventricles (e.g., LVH)
Ventricular volume increases, but pressure stays low (ventricles are compliant)
No valve opens or closes during diastasis
B.11 Heart Cycle. Hemodynamic Evaluation
ECG Correlation of ventricular filling
Atrial contraction = P wave
Ventricular filling ends just before QRS
B.11 Heart Cycle. Hemodynamic Evaluation
What happens during increased HEart Rate
During states of increased heart rate (e.g., during exercise), the duration of diastole decreases so that there is less time for the coronary arteries to fill with blood and supply the heart with oxygen. Patients with narrow coronary arteries, e.g., due to atherosclerosis, will, therefore, experience chest pain (angina pectoris) during exertion.
B.11 Heart Cycle. Hemodynamic Evaluation
Pressure Volume Loop - draw it
B.11 Heart Cycle. Hemodynamic Evaluation
Pressure Volume Loop Defintion
It is the Left Ventricular Pressure-Volume Loop
Used to: measure cardiac performance
Shape: roughly rectangular; each loop is formed in a counter-clockwise directio
B.11 Heart Cycle. Hemodynamic Evaluation
Pressure Volume Loop Stages
1) End-diastolic state: closure of the atrioventricular valve and the beginning of systole (the LV is filled with blood)
(1 → 2) Isovolumetric contraction: With the atrioventricular and semilunar valves closed, contraction increases the internal pressure of the left ventricle; ventricular volume is left unchanged.
(2) Opening of the semilunar valve when the ventricular pressure exceeds the aortic and pulmonary arterial pressure
(2 → 3) Ejection phase: The ventricle pumps out the stroke volume.
(3) Closure of the semilunar valve when the ventricular pressure falls below the aortic and pulmonary arterial pressure
(3 → 4) Isovolumetric relaxation: the beginning of diastole, when the ventricle relaxes and all the valves are closed
(4) Opening of the atrioventricular valve when the ventricular pressure falls below the atrial pressure
(4 → 1) Filling phase: The ventricles receive blood from the atria and a new cardiac cycle begins.
B.11 Heart Cycle. Hemodynamic Evaluation
hemodynamic evalutation defintion
Hemodynamic evaluation involves the assessment of blood flow, pressure, and cardiac performance within the cardiovascular system. It is essential in managing shock, heart failure, valve disease, and critically ill patients.
B.11 Heart Cycle. Hemodynamic Evaluation
Parameters to Know in Hemodynamic Evaluation
Heart Rate (HR) Basic determinant of cardiac output
Blood Pressure (BP) Systemic perfusion pressure
Central Venous Pressure (CVP) Right atrial preload (volume status)
Pulmonary Artery Pressure (PAP) Pressure from RV to lungs
Pulmonary Capillary Wedge Pressure (PCWP) Left atrial pressure surrogate (LV preload)
Cardiac Output (CO) Volume of blood pumped per minute
Cardiac Index (CI) CO adjusted for body size
Systemic Vascular Resistance (SVR) Afterload on the LV
Mixed Venous O₂ Saturation (SvO₂) Tissue oxygen extraction (low = shock or low CO)
B.11 Heart Cycle. Hemodynamic Evaluation
How Parameters a measured in Hemodynamic Evaluation
Noninvasive:
BP cuff
Echocardiography (EF, stroke volume, IVC collapse)
Doppler ultrasound
Invasive:
Arterial line (continuous BP)
Central line (CVP)
Pulmonary artery catheter (Swan-Ganz):
Measures CVP, PAP, PCWP, CO, SvO₂
B.11 Heart Cycle. Hemodynamic Evaluation
Keys to know about hemodynamic evaluation
PCWP > 18 mmHg = pulmonary edema likely cardiac in origin
Low SvO₂ (<65%) = inadequate oxygen delivery (low CO or high demand)
CVP doesn’t equal volume in isolation—interpret with full picture
Echocardiography is the best noninvasive hemodynamic tool
Swan-Ganz catheters are used selectively in complex shock or HF patients
B.11 Heart Cycle. Hemodynamic Evaluation
What is Cardiac Catherization
Cardiac catheterization is a procedure used in the diagnosis and treatment of cardiovascular conditions. It involves the insertion of a catheter into a cardiac vessel (coronary catheterization) or chamber by way of a suitable vascular access (usually a femoral or radial artery). Once in position, a cardiac catheter can help evaluate the blood supply to the cardiac musculature (angiography) or open up narrowed or blocked segments of a coronary artery by means of a coronary angioplasty with stenting (percutaneous coronary intervention, or PCI)
B.11 Heart Cycle. Hemodynamic Evaluation
Coronary angiography/ventriculography
Contrast-enhanced radiological analysis of the heart cavities (ventriculography) or coronary arteries (coronary angiography)
