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THE
CARDIOVASCULAR
SYSTEM
BMP 218
November 25, 2014
IMAGING RESOURCE
http://www.yale.edu/imaging/
CARDIOVASCULAR DISEASE
•  #1
killer of men and women in the United States
•  Causes
one death every 34 seconds
•  Causes
one death/minute in women (more than uterine or breast cancer)
•  Kills
more Americans than the next 5 leading causes of death combined
•  Prevalence:
•  50
million with hypertension
•  13.2
•  5
million with coronary heart disease
million with heart failure
•  4.8
million with stroke
CARDIOVASCULAR SYSTEM
•  Organs
and tissues which circulate blood throughout the body
•  Consists
of:
•  Blood
•  Blood
•  Heart
vessels
BLOOD
•  Only
tissue which flows throughout body
•  Carries
•  Takes
•  Essential
oxygen & nutrients to body cells
waste products back to lungs, kidneys, and liver for disposal
part of the immune system
•  Necessary
for fluid & temperature balance
•  Transports
hormonal messages
BLOOD CHARACTERISTICS
• 
Fluid = plasma (yellow color)
• 
Components
• 
• 
Red blood cells (which make
blood look red)
• 
White blood cells (fight infection)
• 
Platelets (clotting)
Debris (cell fragments, bacteria, etc.)
BLOOD VESSELS
•  Tubes
which carry blood through the body
•  Blood
should flow in only ONE DIRECTION
•  Three
types:
•  Arteries
•  Veins
•  Capillaries
ARTERIES
•  Carry
blood AWAY from the heart
•  Thick,
muscular walls
•  NO
•  Do
VALVES
NOT have to contain oxygenated blood
VEINS
•  Carry
•  Thin
blood TOWARD the heart
walls (little muscle)
•  HAVE
•  May
VALVES
contain oxygenated blood
CAPILLARIES
•  Direct
transfer between cells
and blood
•  One-cell
thickness between
parallel capillaries
VEINS VS. ARTERIES
ARTERIES
•  Arteries
are covered with a muscle layer
•  Artery
expands as the heart pushes blood
•  Artery
recoils when heart is relaxed
•  helps
•  These
to keep blood moving
features are
•  measured
•  can
as BLOOD PRESSURE
be felt as a PULSE
BLOOD PRESSURE
• 
Definition: the pressure of the circulating blood against the walls of the blood
vessels
• 
Two systemic blood pressure numbers:
• 
Systolic (when ventricles contract – first #)
• 
• 
When pulsatile arterial pressure > cuff pressure -> “whoosh” sound with
each beat
Diastolic (when ventricles relax – second #)
• 
When (continuous) arterial pressure > cuff pressure -> loss of “whoosh”
sound
VEINS
•  Little
muscle
•  Blood
easily slowed/stopped
CIRCULATION
ARTERIAL AND VENOUS
CIRCULATION
HEART
•  Primary
“pump” or ”engine” for the cardiovascular system
•  Meeting
point for the 2 circulatory systems
•  Right
•  Left
•  Has
side of heart (pulmonary)
side of heart (systemic)
both ELECTRICAL and MECHANICAL activity
•  Electrical
activity MUST precede mechanical activity
CHAMBERS OF THE HEART
HEART VALVES
LISTENING TO THE HEART
•  Closure
of the heart valves causes the “lub-dub” sound of the
heart
•  “Lub”
•  closure
•  “Dub”
•  closure
(S1 = first heart sound)
of mitral and tricuspid valves
(S2 = second heart sound)
of aortic and pulmonic valves
ELECTRICAL CONDUCTION
ELECTROCARDIOGRAM
CORONARY CIRCULATION
CARDIOVASCULAR TESTING
• 
Needs to detect:
• 
• 
Blood flow abnormalities
• 
peripheral vascular disease (e.g. stroke)
• 
coronary artery disease (e.g. acute myocardial infarction)
Structural abnormalities
• 
Cardiomyopathy
• 
Valve problems
• 
Blood clots
CARDIOMYOPATHY
•  Literally
“heart muscle
disease”
•  Deterioration
of heart
function for any reason
•  Characterized
as
“extrinsic” or
“intrinsic”
CARDIOMYOPATHY
•  Extrinsic
Intrinsic
•  Primary
• Primary
•  most
• Drug
pathology
OUTSIDE the heart
often ischemia
pathology INSIDE
the heart
or alcohol toxicity
• Infection
• Genetic
CARDIOVASCULAR IMAGING
•  Radiography
•  X-ray
Angiography (with contrast)
•  Echocardiography/Ultrasound
•  Computed
Tomography
•  Electron-Beam
•  Spiral
•  MRI
CT
CT (EBCT)
RADIOGRAPHY
CARDIAC CATHETERIZATION/
ANGIOGRAPHY
•  Visualization
of arteries/veins
via injection of a contrast into
the artery/vein of interest
•  Uses
fluoroscopy to obtain
images
CORONARY ANGIOGRAPHY
NORMAL CORONARY
ARTERIES
ANGIOGRAPHY
CEREBRAL ANGIOGRAPHY
ECHOCARDIOGRAM/
ULTRASOUND
COMPUTED TOMOGRAPHY
(CT)
• 
• 
Spiral (helical) CT
• 
spiral shape of path of x-ray beam during scanning
• 
faster than standard CT
• 
desirable for vascular studies
Electron beam tomography (EBCT)
• 
• 
No moving parts – even faster
Usually uses dynamic imaging contrast with contrast
• 
“CT Angiography (CTA)”
CT OF CAROTID ARTERIES
ECHOCARDIOGRAM/
ULTRASOUND
CT ANGIOGRAPHY
TIME-OF-FLIGHT
MR ANGIOGRAPHY
•  TOF-MRA
•  Stationary
uses heavily T1-weighted 3D gradient echo MRI
spins become “saturated” from repeated pulsing at
TR < T1
•  Stationary
•  Blood
spins produce hypointense signal
flow washes fresh unsaturated spins into the imaging
volume
TIME-OF-FLIGHT
MR ANGIOGRAPHY
3-D ANGIOGRAPHIC
PROJECTIONS FROM MRI
•  Projection
renderings simulate
conventional angiography
•  Post-hoc
selection of viewing
perspective
TRUE FISP IMAGING
HEART CINEMATIC STUDIES
MRI CONTRAST REAGENTS
AND T1
•  Typical
contrast reagents are
chelates of metals ions having
unpaired electron spins
•  Water
molecules must “touch”
the agent to enhance T1 relaxation
•  Molecular
structure causes agent to
(mostly) stay within vascular system
•  Large
signal enhancement in
vascular system
CONTRAST ENHANCED MRA
• 
Rapid (10-20 sec) T1-weighted
gradient echo imaging
• 
Often 2 dimensional (thick slices)
• 
Imaging timed so that imaging
coincides with arterial phase of the
contrast
• 
Complete angiographic coverage from
arotic arch to Circle of Willis
• 
Other peripheral vascular applications
MR ANGIOGRAPHY (MRA)
•  MIP
– Maximal Intensity
Projection
•  Heart
and Pulmonary
Circulation
•  3D
volume
reconstructionHead and
Neck Vasculature
• Projection renderings simulate conventional
• Post-hoc selection of viewing perspective
angiography
MYOCARDIAL PERFUSION
WITH MRI CONTRAST AGENT