Download (Un)Healthy Hearts

(Un)Healthy Hearts
AN EXPLANATION OF COMMON DISEASES AND EVENTS OF THE
CARDIAC SYSTEM
Disclosures
I am a medical student
This session is not intended to give you a diagnosis or replace going to see your health care
professional
What we will discuss
 Basic cardiac physiology: The pump and the pipes
 Rate and Rhythm
 Blood pressure
 Atrial fibrillation
 Hypertension
 Stroke
 Heart Attack
Pop quiz
1) Which chambers of the heart receive blood? Which chambers pump it away?
2) What does it mean to have a sinus rhythm?
3) What is the difference between an EKG, an ECG, and an Echocardiogram?
4) What is hypertension?
5) True or false hypertension is the number one modifiable risk factor for stroke.
Cardiology Basics
HOMEOSTASIS
P LUMBI NG
R AT E A N D R HYT HM
Homeostasis
 Maintaining the constancy of our internal environment
Temperature
Oxygen concentration
Carbon Dioxide concentration
pH
Ionic composition
Osmolarity
Plumbing
HTTP://WWW.HILLMAN-CONSULTING.CO.UK/LOGISTICS-IMAGES/HEART-PIC.JPG
The Pump
4 Chambers
 2 Atria
 2 Ventricles
4 Valves
 Tricuspid
Pulmonary
Mitral
Aortic
Blood Flow
RA
RV
Lungs
LA
LV
Body
RA
From: The Circulatory System
Junqueira's Basic Histology, 14e, 2016
Date of download: 11/29/2016
https://www.youtube.com/watch?v=JA0
Wb3gc4mE
Copyright © 2016 McGraw-Hill Education. All rights reserved.
Blood circulation
clip
Clinical side note
The lub dub of your heart is the sound of your valves closing
 Lub=closure of atrio ventricular valves=S1
 Dub=closure of aortic and pulmonary valve=S2
https://www.youtube.com/watch?v=gJpT_wHZeF8
A heart murmur is an extra or unusual sound heard during a heartbeat
https://www.youtube.com/watch?v=i2dtQu5Ow1U
The Pipes:
Vasculature
From: Chapter 1. Overview of the Cardiovascular System
Cardiovascular Physiology, 8e, 2014
Date of download: 11/29/2016
Copyright © 2016 McGraw-Hill Education. All rights reserved.
Basic things to
keep in mind
All blood vessels except for
capillaries have three layers
The thickness of each layer is
dependent on the function of the
vessel
Elastic Arteries
Conducting vessels
Thick elastic layer in order to expand
and temporarily store a portion of
blood ejected during ventricular
systole
Capable of dealing with high
pressure loads
Passive recoil supplies blood to
organs down stream
From: The Circulatory System
Junqueira's Basic Histology, 14e, 2016
Date of download: 11/30/2016
Copyright © 2016 McGraw-Hill Education. All rights reserved.
Large Veins
Large diameter lumen to function as
capacitance vessels
A thin medial layer with circumfrencial
smooth muscles and collagen fibers
A thick adventitial layer containing
collagen, elastin and longitudinally
arranged bundles of smooth muscle
From: The Circulatory System
Junqueira's Basic Histology, 14e, 2016
Date of download: 11/29/2016
Copyright © 2016 McGraw-Hill Education. All rights reserved.
Medium Arteries
and Veins
Arteries:
 Distributing vessels
 Help to regulate blood pressure
Veins:
 Thin intimal layer with a few
smooth muscles
 Thick adventitial layer with
network of collagen and elastic
fibers
From: The Circulatory System
Junqueira's Basic Histology, 14e, 2016
Date of download: 11/29/2016
Copyright © 2016 McGraw-Hill Education. All rights reserved.
Arterioles and
Venules
Arterioles
 Control blood flow to capillaries by
constriction of smooth muscle in
medial layer
Venules
 Thin walls and big lumens.
 Have more muscle with increased
size
From: The Circulatory System
Junqueira's Basic Histology, 14e,
2016
Date of download: 11/30/2016
Copyright © 2016 McGraw-Hill Education. All rights reserved.
Capillaries
 Constitute 90% of blood vessels
 Lumen large enough for a single
RBC
 Single layer of endothelial cells
 Site of transfer
From: The Circulatory System
Junqueira's Basic Histology, 14e, 2016
Date of download: 11/29/2016
Copyright © 2016 McGraw-Hill Education. All rights reserved.
Coronary
Vasculature
Blood vessels that supply the heart muscle with
oxygen and nutrients
Left and right coronary arteries originate at the
base of the aorta
Perfusion happens during diastole
Coronary sinus is the principle coronary vein
and dumps back into the right atrium directly
These are the important ones when we are
talking about heart attacks
Cardiac
Excitation
 SA node contains pace maker cells
that self depolarize and initiate
electrical signal
 Depolarize=send electrical signal
 AV node contains slowly
conducting cells
 Purkinje fibers rapidly conduct
electricity to ensure that all
ventricular cells contract at the
same time
 Note: All cardiac cells are capable
of self depolarizing
Purkinje fibers
From: Chapter 1. Overview of the
Cardiovascular System
Cardiovascular Physiology, 8e, 2014
Date of download: 11/30/2016
Copyright © 2016 McGraw-Hill Education. All rights reserved.
Rate and
Rhythm
Evaluate using an EKG also known as
an ECG
From: Electrocardiography
Harrison's Principles of Internal Medicine, 19e,
2015
Date of download: 11/30/2016
Copyright © 2016 McGraw-Hill Education. All rights reserved.
Blood Pressure
Basic Physics of Blood Flow
Flow=Pressure difference/Resistance
Poiseuille’s equation states the Resistance=n/(ß•r^4)
Flow= (∆P•ß•r^4)/n
∆P=Flow•Resistance
BP=CO•R=SV•HR•R
Blood Pressure Control
Short Term Neural Control
 Constriction or dilation of vessels
 Increase or decrease of cardiac output
Balance of sympathetic and parasympathetic nervous system signals
 ß adrenergic receptors
BP=CO•R=SV•HR•R
Blood Pressure Control
Long Term Renal Control
BP is dependent on blood volume
 Regulation of solute and water retention by the kidneys
 Renin-Angiotensin-Aldosterone System
 Renin is released in response to
1. low afferent arteriole pressure
2. Sympathetic stimulation of ß1-adrenoreceptors
3. Low Na+ sensed by macula densa in the distal tubule inhibits renin release
BP=CO•R=SV•HR•R
Pharmacological side note
Anti hypertensive medications target
ß andrenergic receptors
Renin-Angiotensin-aldosterone system
Solute and water retention
BP measurement methods
Office (attended, OBPM)
Auscultatory (mercury, aneroid)
Oscillometric (electronic)
http://www.dableducational.org/sphygmomanometers.html
http://www.bhsoc.org/bp-monitors/bp-monitors/
Hypertension
Hypertension
 BP is a normally distributed biological variable
 Estimate 41% of people 35-70 y/o have HTN but only 46.5% are aware of dx
 In Canada 22% of 20-79 y/o have hypertension
Raised BP is the biggest single contributor to the global burden of disease and global mortality
 Initially a disease of the wealthy but has become a disease linked to low socioeconomic status
JAMA 2013 SEP 4;310(9):959
CMAJ 2008 MAY 20;178(11):1441
Hypertension
 Dx made based on an arbitrary cutoff point for a variable that has a graded relation with risk
across its entire range
 Geoffrey Rose define HTN as a BP for which investigation and management do more good than
harm
 Most guidelines define hypertension as a BP≥140/90
Asymptomatic
II. Criteria for the
diagnosis of
hypertension
and
recommendations
for follow-up:
overview
Measurement using electronic (oscillometric) upper arm devices is preferred over auscultation
ABPM: Ambulatory Blood Pressure Measurement
AOBP: Automated Office Blood Pressure
HBPM: Home Blood Pressure measurement
OBPM: Office Blood Pressure measurement
Hypertension
Primary (Essential) HTN (95%)
Later onset
Combination of lifestyle and genetic factors
Secondary HTN (5%)
Early onset
No family history of hypertension
Resistant to typical hypertensive treatment
Clear cause
Hypertension is a risk factor for…
Coronary artery disease
Heart Failure
Chronic kidney disease
Stroke
Intracerebral hemorrhage
Transient ischemic attack
Peripheral arterial disease
Aortic Regurgitation
Atrial Flutter
Mild cognitive impairment
Pathological Consequences
Peripheral arteries
HTN causes damage to blood vessels
Arteriosclerosis: hardening of arteries
Atherosclerosis: fat deposition in arterial walls
Hyperplastic arteriosclerosis: Thickening of the tunica media of muscular arteries
Aortic dissection
Peripheral arterial disease
Atherosclerosis
of a coronary
artery
Pathological Consequences
Kidneys
Renal injury and End Stage Renal Disease
Ischemic changes in glomeruli and post-glomerular structures
Loss of autoregulation of renal blood flow ➡ hyperfiltration, hypertrophy and glomerular
sclerosis= vicious cycle
Pathological Consequences
Heart
LV hypertrophy increases risk of CHD, stroke, CHF, sudden death
Heart disease is the most common cause of death in hypertensive patients
Accelerated atherosclerosis of coronary arteries ➡ Ischemic heart disease
Hypertensive heart disease ➡left ventricular hypertrophy ➡ right ventricular hypertrophy ➡
CHF
Cardiac arrhythmias
Left Ventricular
hypertrophy
Chest pain
Many reasons but a common reason is a lack of oxygen getting to the heart muscle
How does oxygen get to the heart muscle? Coronary arteries
Blockage of coronary arteries means the heart does not get the oxygen it needs
Ischemia: inadequate blood supply to a region
Infarction: obstruction of blood supply to a region causing death of tissue
Heart attack=MI
Angina: characteristic chest pain brought on by exertion and relieved with rest
Acute coronary syndrome: NSTEMI or STEMI (Heart Attack)
9/10 of heart attacks are due to atherosclerosis
STEMI ECG
Atrial Fibrillation
Atrial
Fibrillation
 A supraventricular tachyarrhythmia
caused by uncoordinated atrial
activation and associated with
irregular ventricular response
 Irregularly irregular rhythm
Most common arrhythmia Dis Mon
2013 Mar;59(3):67
1-2% prevalence in general
population Eur Heart J. 2010
Oct;31(19):2369-429
https://www.youtube.com/watch?v=
NNkkzWcseA0
Atrial Fibrillation
Risk Factors
Increased atrial strain: Valvular heart disease, hypertension, CHF
Increased atrial irritability: Thyrotoxicosis, alcohol, stimulants, pericarditis, pneumonia/sepsis,
cardiac surgery
Age
Sleep apnea, renal failure, diabetes, COPD
Atrial Fibrillation
Symptoms
Palpitations
Dizziness, Pre-syncope/syncope
SOB, Chest pain
Fatigue, Decreased exercise tolerance
Arial Fibrillation
Diagnosis
12 lead ECG
24 hour holter monitor
2 week event monitor
Implantable loop recorder
Atrial Fibrillation
Complications
Atrial thrombus ➡ Stroke, Systemic embolization
Fall risk
Stroke
Stroke
 A sudden diminution or loss of
consciousness, sensation, and
voluntary motion caused by the
rupture or obstruction of a blood
vessel of the brain-MerriamWebster dictionary
 Leading cause of disability in
Canada
 50000 strokes/year
Signs and
Symptoms
Risk Factors
ISCHEMIC
HEMORRHAGIC
Hypertension
Hypertension
Smoking
Age
Excessive alcohol
Male sex
Stress
Excessive alcohol
Poor diet
Physical inactivity
Prevention
Smoking cessation
Exercise
Diet
Come to Sergiy’s talk next weekend on preventative medicine
Pop quiz
1) Which chambers of the heart receive blood? Which chambers pump it away?
2) What does it mean to have a sinus rhythm?
3) What is the difference between an EKG, an ECG, and an Echocardiogram?
4) What is hypertension?
5) True or false hypertension is the number one modifiable risk factor for stroke.
Questions
Types of Stroke
Ischemic
Atrial Fibrillation
Pathogenesis
Causes may trigger cellular hypertrophy, activation of
fibroblasts, and/or tissue fibrosis that lead to alterations in
ion channel functioning, calcium homeostasis and atrial
structure
Structural and electrophysiological changes lead to atrial
remodeling
Atrial remodeling can generate and further perpetuate
atrial arrhythmia