Cardiovascular System

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Cardiovascular System

• John P. McDonough,
• CRNA, Ed.D., ARNP

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Vessels

• Arteries
• carry blood away from the heart
• oxygenated (except PA)
• Veins
• carry blood to the heart
• desaturated (except PV)
• Capillaries
• local circulation
• connects arteries to veins

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Great Vessels

• Vena cava
• superior inferior
• Pulmonary artery
• Pulmonary vein
• Aorta

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Blood Flow Through the Heart

• Rt Atrium
• Tricuspid valve
• Rt ventricle
• Pulmonic valve
• Lt atrium
• Mitral valve
• Lt ventricle
• Aortic valve

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Structure of the Heart

• Pericardium
• visceral
• parietal
• pericardial fluid
• Myocardium
• contractile heart muscle
• Endocardium
• cavity lining

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Circulation to the Heart Itself

• Lt main coronary artery
• Lt anterior descending
• Lt circumflex
• Rt coronary artery
• Coronary perfusion
• occurs during diastole
• rate changes effect diastole only

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Cardiac Conduction System(electrical ?
mechanical function)

• Sinoatrial (AS) node
• pacemaker of the heart
• Intra-atrial conduction pathways
• Atrioventricular (AV) node
• Bundle of His
• Rt bundle branch
• Lt bundle branch
• Lt anterior posterior facicles

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Circulatory System

• 2 separate circuits, serially connected
• Output of one ? the input of the other
• pulmonary, systemic
• Heart is functions as 2 pumps
• Rt pulmonary, Lt systemic
• Arteries
• Veins
• Capillaries

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Adrenergic Control of Heart Rate

• ?-adrenergic receptors (generally dilates
  excites)
• ?1 found mostly in the heart (conduction system)
• ?2 found mostly in the lungs (bronchi), but also
  in the coronary arterioles

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Adrenergic Control of Heart Rate

• ?-adrenergic stimulation will ? heart rate
  dilate bronchi
• ?-adrenergic blockade will ? heart rate
  constrict bronchi
• Norepinephrine binds with ?1 receptors
• Epinephrine binds with ?2 receptors

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Adrenergic Control of Heart Rate

• ?-adrenergic receptors
• some in the heart, but mostly in vessels
• Stimulation causes constriction

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Autonomic Control of Heart Rate

• Sympathetic
• thoracic chain ganglia
• neurotransmitter norepinephrine (NE)
• parasympathetic
• vagus nerve (CN-X)
• neurotransmitter acetylcholine (Ach)

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Other Controls of Heart Rate

• Volume control
• Barinbridge reflex
• Pressure control
• baroreceptors

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Factors Effecting Cardiac Output

• Preload
• Afterload
• Heart Rate
• Contractility

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1, 300, 000 Myocardial Infarctions yearly in the
United States

• 50 are fatal

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Risk Factors for CV Disease

• Smoking
• Diabetes mellitus
• Hypertension
• Hyperlipidemia

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Risk Factors for CV Disease (cont)

• Genetic predisposition
• Obesity
• Sedentary life-style
• Type A personality

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Hypertension

• 50 million Americans have it
• Diagnosed if gt2 B/P measurements show
• diastolic readings gt90
• average of 2 systolic gt140
• Mortality rates
• white women 4.7
• white men 6.3
• black women 29.3
• black men 22.5

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Determinants of Hypertension

• Essential hypertension
• stress
• diet
• genetic factors
• Secondary hypertension
• pheochromocytoma
• renal vascular disease
• Cushings syndrome
• thyrotoxicosis

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Effect of Vessel Diameter

• With the same 100mg/Hg pressure driving
• d1 ? 1 ml/min
• d2 ? 16 ml/min
• d3 ? 256 ml/min

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Complications of Hypertension

• Myocardial ischemia
• Ventricular failure
• Pulmonary edema
• Aortic dissection
• Intracerebral hemorrhage

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Common Antihypertensives
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Cardiomyopathies

• Primary disorders of the muscle itself
• not related to CAD, HTN or valve disorders
• Dilated cardiomyopathy
• toxins, ETOH, infection, nutrition,
• Hypertrophic cardiomyopathy
• usually congenital
• Restrictive cardiomyopathy
• usually infiltrative disease process

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Congestive Heart Failure(a symptom complex)

• Each side of the heart can fail separately
• Left HF is a frequent cause of right HF
• frequent, but the not the only
• S/S Left heart failure
• dyspnea
• pulmonary congestion
• S/S Right heart failure
• peripheral edema
• vein distention

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Treatment of CHF

• Rate control
• Digitalis glycosides (lanoxin)
• Diuretics
• Phosphodiesterase (PDE) inhibitors

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Cardiac muscle extracts the largest amount of
oxygen because of the extensive work the heart
does (manifested as contractility) even during
rest.At rest 8-10 ml O2/min/100g of
myocardium.During exercise this can increase by
a factor of 10.
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But what drives the contraction process in
myocytes?
Answer ATP
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As demand goes up, inotropic response of the
heart increases and the coronary vasculature
adapts by vasodilating to provide an adequate
oxygen supply. If, due to atherosclerotic
disease, the coronary arteries are unable to
sustain the myocardium, ischemia ensues and the
flow is predicted by Q ? ?P r4/ 8 n
L where r is radius of vessel, n is viscosity
and L is vessel length.
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Factors in Supply Demand

• Decreased supply
• reduced content
• reduced coronary flow
• increased LV pressure
• fixed vascular obstruction

• Increased demand
• positive chronotropism
• positive inotropism
• increased LV volume
• increased wall tension
• increased afterload

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Visualization of intracellular oxygenation Micros
pectrophotometry Reference Takahashi, E. and K.
Doi. Visualization of oxygen level inside a
single cardiac myocyte. Am. J. Physiol. 268
H2561-H2568, 1995.
Aerobic environment Happy myocytes
Anoxic environment Myocytes not happy
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History

• Pain
• Dyspnea
• Palpitation
• Edema
• Syncope
• Fatigue Weakness
• Cyanosis

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Hemodynamic to Formulae

• BP CO x SVR
• CO SV x HR
• SV LVEDV - LVESV
• SVR MAP - CVP x 80 / CO
• normal 800-1200 dyne/sec/cm-5

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Congestive Heart Failure (diagnostic problems)

• Volume overload
• Bronchospasm
• Pneumonia
• Pulmonary embolism
• Ischemically mediated pulmonary edema

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Characteristics of Chest Pain

• ANGINA
• retrosternal, diffuse
• Lt arm, jaw, back
• aching, dull, pressing, squeezing,
• minutes
• effort, emotion, eating cold
• rest, NTG

• PROBABLY NOT
• Lt inframam, localized
• Rt arm
• sharp, cutting, shooting,
• seconds, hours, days
• respiration, posture, motion
• nonspecific

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Cardiac Causes of Chest Pain

• CAD
• aortic valve disease
• pulmonary hypertension

• mitral valve prolapse
• pericarditis
• IHSS

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Pulmonary Causes of Chest Pain

• pulmonary embolism
• pneumonia
• pleuritis
• pneumothorax

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Musculoskeletal Causes of Chest Pain

• costochondritis
• arthritis
• muscular spasm
• bone tumor

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GI Causes of Chest Pain

• ulcer disease
• bowel disease
• hiatal hernia
• pancreatitis
• cholecystitis

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Other Causes of Chest Pain

• Vascular
• aortic dissection
• Emotional
• anxiety
• despression

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Common Causes of Palpitations

• extrasystoles
• tachyarrthymias
• bradyarrthymias
• drugs

• smoking
• caffeine
• thyrotoxicosis

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Common Causes of Dyspnea

• Cardiac
• Lt failure
• mitral stenosis
• Pulmonary
• obstructive disease
• asthma
• restrictive disease
• pulmonary HTN

• Emotional
• High altitude exposure
• Anemia

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Physical Exam of the Heart

• inspection
• blood pressure
• assess arterial pulse
• assess JV pulse

• percussion
• palpation
• auscultation
• evaluation of edema

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Murmur Description

• timing in cycle
• location
• radiation
• duration
• intensity

• pitch
• quality
• relationship to position
• relationship to respiration

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Grading of Murmurs (I-V/VI)

• I lowest intensity
• II low intensity
• III medium intensity (without thrill)
• IV medium intensity (with thrill)
• V loudest murmur with scope on chest
• VI loudest, heard with scope off chest

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Location of Murmurs within Cardiac Cycle
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Shape of Murmurs
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Three Most Important Survival Factors

• MYOCARDIAL PRESERVATION
• MYOCARDIAL PRESERVATION
• MYOCARDIAL PRESERVATION
• Dead meat dont beat!