Cardiology Flashcards
Carries deoxygenated blood to the lungs
Pulmonary artery
Carries oxygenated blood from the lungs
Pulmonary vein
Pressure in the right atrium (Central Venous Pressure)
0 mmHg
Mitral & Tricuspid valves
AV Valves
Aortic & Pulmonic valves
Semilunar Valves
64% of blood volume is found in:
Veins (Reservoir of blood)
Found between myocardial cell membranes
Intercalated discs (with Gap junctions)
Found in Intercalated discs
Gap Junctions
Heart Rate (HR) x Stroke Volume (SV)
Cardiac Output (CO)
Cardiac output of Left & Right Heart
Equal (Resting: 5L/min) (due to higher resistance in pulmonary vessels)
Blood Flow Velocity: Highest
Aorta
Blood Flow Velocity: Lowest
Capillaries
“Stressed Volume”; Thick-walled, under high-pressure
Arteries
“Control conduits for blood flow”; Mainly under sympathetic control
Arterioles
Alpha 1: smooth muscle contraction ➡️ Vasoconstriction
Increases Total Peripheral Resistance (TPR) or Systemic Vascular Resistance (SVR)
Beta 2: smooth muscle relaxation ➡️ Vasodilation
Decreases Total Peripheral Resistance (TPR) or Systemic Vascular Resistance (SVR)
No Vasoconstriction or Vasodilation; Composed of single layer of endothelial cells; No smooth muscle layer; Closed Loop
Capillaries
“Unstressed Volume”; Thin-walled, under low pressure; With one-way valves
Veins
What happens when systemic arterioles vasoconstrict?
TPR/SVR: IncreasesBlood flow: Decreases
What happens when systemic arterioles vasodilate?
TPR/SVR: DecreasesBlood flow: Increases
What happens to blood pressure when TPR increases?
Blood Pressure: Increases (BP=COxTPR)
What happens when veins vasoconstrict?
Venous Return: Increases (CO & BP: Increases too)
Change in Pressure / Resistance
Ohm’s Law
Viscosity x Length / Radius
Poiseuille’s Law
Density x Diameter x velocity / viscosity
Reynold’s Number
Volume / Pressure
Compliance orCapacitance
Streamlined (straight line) flow; Velocity: highest at the center, lowest at the walls
Laminar Flow
Disorderly flow; Associated with High Reynold’s Number; Seen in Anemia
Turbulent Flow
Reynold’s Number: Laminar Flow
<2000
Reynold’s Number: Turbulent Flow
> 2000
“A strain in the structure of a substance produced by pressure, when its layers are laterally shifted in relation to each other”
Shear
Highest Shear
At the Walls of the vessels
Lowest Shear
At the Center of the vessel
Consequence of Shear
Decreases Blood Viscosity
Compliance of Veins vs Arteries
24x Higher Compliance
Compliance: Effect of Aging
Decreases Compliance
Highest arterial pressure
Systolic Pressure
Lowest arterial pressure
Diastolic Pressure
Difference: Systolic Pressure - Diastolic Pressure
Pulse Pressure
Stroke Volume (SV) / Arterial Compliance
Pulse Pressure
Synonym: Right Atrial Pressure
Central Venous Pressure
2/3 (Diastole) + 1/3 (Systole)
Mean Arterial Pressure
Used to estimate Left Atrial Pressure
Pulmonary Capillary Wedge Pressure
Blood Pressure: Large Arteries
120/80 mmHg
Blood Pressure: Systemic Capillaries
17 mmHg
Blood Pressure: Vena cava
0 mmHg
Blood Pressure: Pulmonary arteries
25/8 mmHg
Blood Pressure: Pulmonary Capillaries
7 mmHg
True or False: BP Systemic Circulation < BP Pulmonic Circulation
False (>)
True or False: CO Systemic Circulation > CO Pulmonic Circulation
False (=)
Increased Systole; Normal Diastole; Increased Pulse Pressure
Arteriosclerosis
Decreased Systole; Normal Diastole; Decreased Pulse Pressure
Aortic Stenosis
Increased Systole; Decreased Diastole; Increased Pulse Pressure
Patent Ductus Arteriosus (PDA)
Increased Systole; Decreased Diastole; Increased Pulse Pressure (End-diastolic Pressure increases)
Aortic Regurgitation
Atrial Depolarization
P wave
Corresponds to AV Node Conduction
PR Segment
Correlates with conduction time/velocity through AV Node
PR Interval
Ventricular Depolarization
QRS Complex
Ventricular Repolarization
T wave
Period of Depolarization + Repolarization of Ventricles
QT Interval
Correlates with plateau of Ventricular action potential
ST Segment
What happens when Sympathetic NS stimulates the AV Node?
Conduction Velocity: IncreasesPR Interval: Decreases
What happens when Parasympathetic NS stimulates the AV Node?
Conduction Velocity: DecreasesPR Interval: Increases
What is the effect of Potassium on the ECG?
Hyperkalemia: Tall T WavesHypokalemia: Flat T waves
What is the effect of Calcium on the ECG?
Hypercalcemia: Shortened QT IntervalHypocalcemia: Prolonged QT Interval
What is the effect of MI on the ECG?
STEMI: ST Elevation, Q WavesNSTEMI: ST Depression
Abnormally prolonged interval between the QRS Complex and T Wave that may cause Sudden Cardiac Death in the children?
Long QT Syndrome (In Adults: Brugada Syndrome; In Athletes: Hypertrophic Cardiomyopathy)
Master pacemaker; Has unstable RMP; No sustained plateau
SA Node
Slowest conduction velocity (0.01-0.05m/sec)
AV Node
Fastest conduction velocity (2-4m/sec)
Bundle of His, Purkinje Fibers, Ventricles