Intro to Murmurs and Hemodynamics

Question 1

Causation of Murmurs

Answer 1

Structural defects
Valves unable to open (stenosis)
Valves unable to close (regurgitation aka insufficiency)
Intracardiac shunt (e.g., ventricular septal defect)

Physiologic murmurs
Associated with high cardiac output states or reduced hematocrit

Question 2

Systolic vs. Diastolic Heart Murmurs

Answer 2

PASS PAID
Pulmonic aortic stenosis is systolic
Pulmonic aortic insufficiency are diastolic

Then opposite for tricuspid and mitral valves

Question 3

Aortic Stenosis Murmur

Answer 3

Aortic stenosis: murmur associated with blood flow into aorta from ventricle between S1 and S2 during ejection

Question 4

Aortic Regurgitation Murmur

Answer 4

Aortic regurgitation: murmur associated with blood flow from aorta back into ventricle between S2 and next S1

Question 5

Pulmonic Stenosis Murmur

Answer 5

Pulmonic stenosis: murmur associated with blood flow into pulmonary artery between S1 and S2

Question 6

Pulmonic Regurgitation Murmur

Answer 6

Pulmonic regurgitation: murmur associated with blood flow from pulmonic valve to R ventricle between S2 and next S1

Question 7

Clinical Manifestations of Valve Disease

Answer 7

Fatigue & dyspnea
Reduced exercise capacity
Light headedness or fainting (syncope)
Heart failure
Pulmonary hypertension
Pulmonary/systemic edema
Chest pain (angina)
Arrhythmias
Thromboembolism

Question 8

Fatigue, Dyspnea, Exercise, Lightheadedness

Answer 8

If not enough CO then fatigue and dyspnea

Maintain situation at rest most of the time, but then when you increase CO via exercise then manifest this valve disease

Lightheadedness or fainting: aortic regurgitation have huge changes in BP, so when increasing activity the diastolic pressure decreases

Question 9

Heart Failure, Pulmonary HTN, Compensations

Answer 9

Most valve diseases if untreated will lead to heart failure

Each compensation for valve disease: remodeling and dilation of heart over time to increase CO and over time you lose the ability to maintain your CO

Pulmonary HTN: very much a common outcome from valve disease; stenotic mitral valve for example you have backflow in pulmonary circuit and get pulmonary HTN and edema in lungs

Question 10

Systemic Edema, Chest Pain, and Arrhythmias

Answer 10

Systemic edema: R valve disease and R heart failure lead to higher systemic pressures and more leaking from vessels

Any type of increase in activity of heart because of valve disease (must work harder) and leads to O2 inbalance and amount of demand of O2 leading to chest pain

Arrhythmias: chambers of heart can get stretched out and ruin the normal conduction wires in the heart
Thrombi: pockets that clots can form and if dislodge can cause stroke

Question 11

Flow, Pressure, and Resistance

Answer 11

Flow: change in P / R

Resistance: what is supplied by the narrowed/open segment that it is crossing
Pressure gradient: whatever is pushing behind the blood

F = (P1 - P2) / R
P1 = proximal pressure
P2 = distal pressure

Question 12

Change in Pressure in Relation to Flow and Resistance

Answer 12

Change in P = F * R
Resistance * 1 up to a certain part, then when double resistance then cut the flow in half = simple linear relationship
If double pressure and resistance then get the same flow

A valve with high resistance (e.g., stenosis) has a high pressure gradient across the valve - proximal pressure increases, distal pressure decreases

Aortic stenosis; pressure gradient across the small valve it increases L ventricular pressure because body is trying to maintain a given mean arterial pressure ALWAYS, so body senses this and changes CO to maintain it

In order to keep the same MAP the L ventricular pressure increases; as the stenosis becomes more and more severe you lose more and more pressure and soon you cannot supply the pressure to maintain the mean arterial pressure

Question 13

Poiseuilles’ Equation

Answer 13

F = r^4 * change in P / viscosity * length

Resistance is proportional to 1/A^2 or viscosity*length/r^4

Question 14

Relationship between Valve Pressure Gradient, Resistance and Flow

Answer 14

Pressure gradient across the aortic valve is the L ventricular pressure (proximal pressure) – aortic pressure ; normally 1mmHg, but as resistance goes up it becomes more
As area becomes smaller the resistance becomes greater

A reduction in valve orifice area causes a disproportionate increase in the pressure gradient across the valve
The pressure gradient across valves increases in diseased valves that have reduced cross-sectional areas (stenosis)

Question 15

Changes in Flow

Answer 15

An increase in flow across a valve causes a proportionate increase in the pressure gradient across the valve in the absence of turbulence

Flow across valves increases during exercise and pregnancy

Since change in P = F * R
If F increases by 4, and resistance stays the same, then 4P (P has a 4 fold increase)

Question 16

Laminar vs. Turbulent Flow

Answer 16

Parabolic shape for laminar flow

Turbulence through stenotic lesion or valve: as all the blood flows through it enters high energy profiles and dramatic increase the pressure gradient
Murmurs: in heart
Bruits: peripheral from heart

Question 17

Turbulence Locations and Relationship to Pressure

Answer 17

In ascending aorta especially at high ejection velocities (results in functional or physiologic murmurs)
Distal to stenotic valves or vessels
Distal to arterial branch points

Turbulence increases energy losses and resistance to flow so that the pressure gradient across a valve increases disproportionately to the flow
For example, a 4-fold increase in flow when there is turbulence causes more than a 4-fold increase in pressure gradient

Question 18

Flow, Velocity, and Area

Answer 18

F = V * A
where A = r^2 and V is proportional to 1/r^2

Reduced cross sectional area or radius by ½ and this causes a 4 fold increase in velocity
If r = 4 then decreases to 2, then A goes from 16 to 4. In order to keep F the same, V must increase from 1 to 4 to keep F at 16

Question 19

Aortic Stenosis in Relation to P, V, Turbulence, and SV

Answer 19

Aortic Stenosis: increases P gradient, velocity, and turbulence and decreases outflow (SV)

LVP increases because aortic stenosis and AP decreases; losing energy and get decrease SV and outflow because increased resistance
Increase in velocity and turbulence because smaller cross sectional area