First Aid: Cardiovascular
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What are the blood supplies of the cardiac interventricular septum?
anterior septum: LAD
- posterior septum: (PD)
- 80%: RAD
- 20%: CFX
What supplies blood to the SA and AV nodes?
right anterior descending coronary
What non-cardiac symtpoms are associated with an enlarged left atrium?
- left atrium = most posterior
- left atrium enlargment = esophageal impingment
- dysphagia: obstruction
- hoarseness: impingement of laryngeal nerve (vagus)
What maintains cardiac output during exercise?
cardiac output = SV x HR
- early exercise: SV
- late exercise: HR
What is the mechanism of decreased cardiac output related to ventricular tachycardia?
- decreased preload/EDV
- if HR is too high, diastolic filling is incomplete
SV = EDV - ESV
What affects stroke volume?
- preload (EDV)
- afterload (MAP, peripheral resistance)
What increases contractility?
- 1. catecholamines: increase SR calcium pump
- 2. increased intracellular calcium
- 3. digitalis: decreased ATPase pump, increased intracellular sodium (causes increased Ca2+)
- 4. decreased extracellular sodium: decrease Na+/Ca2+ exchanger
What decreases contractility?
- 1. decreased B1 signaling: decreased cAMP
- 2. heart failure
- 3. acidosis
- 4. hypoxia/hypercapnea
- 5. non-dihydropyridine CCB
What increases myocardial O2 demand and promotes vulnerability to ischemic damage?
- 1. increased afterload
- 2. increased heart rate
- 3. increased heart size
- 4. increased contractility
What increases preload?
- 1. exercise
- 2. overtransfusion: increased blood volume
- 3. excitement: sympathetic stimulation
What is an example of a venodilator and what is its main effect?
- venodilates: decreases preload
What is an example of a vasodilator and what is its main effect?
- vasodilator: decreases afterload
What is the ejection fraction of the heart?
- measure of contractility
- normal: >55%
- EF = SV/EDV = (EDV - ESV)/EDV
Which conditions generally increase blood viscosity? What cardiovascular effect does this have?
- increase blood viscosity:
- polycythemia vera
- hyperproteinemic states (e.g. multiple myeloma)
- hereditary spherocytosis
cardiovascular effect: increased viscosity increases resistence on vessels
What vessel type accounts for most of the total peripheral resitance?
resistance vessels that regulate capillary blood flow
What decreases total peripheral resistance? What CV effect does this have?
- AV shunt
- CV effect:
- increased venous return
- increased CO
What increases total peripheral resistance? What CV effect does this have?
- CV effect:
- decreased venous return
- decreased CO
What decreases cardiac inotropy? What CV effect does this have?
- heart failure
- narcotic overdose
CV effect: decreased CO
What is the operating point of the heart?
- = when CO is equal to venous return
- = intersect of cardiac/vascular function curves
What does the X-intercept on a cardiac/vascular function curve signify?
- = mean systemic pressure
- = venous return at 0
Which murmurs increase in intensity with inspiration?
right sided heart murmurs
inspiration = increased pulmonary artery flow/volume, decreased left atrium return
Which murmurs increase in intensity with expiration? Why?
left sided heart murmurs
exhilation = increased left atrium return
Which murmurs increase in intensity with hand grip maneuver? Why?
- increased murmurs:
- mitral regurgitation
hand grip maneuver: increases systemic vascular resistance
Which murmurs increase in intensity with the Valsalva maneuver? Why?
- (most murmurs decrease)
- increased murmurs:
- mitral valve prolapse
- hypertrophic cardiomyopathy
Valsalva: decreases venous return
Which murmurs decrease in intensity with rapid squatting? Why?
- decreased murmurs:
- hypertrophic cardiomyopathy
- mitral valve prolapse
- rapid squatting:
- increases venous return
- increases afterload
How is a hypertrophic cardiomyopathy murmur best heard?
- systolic murmur
- left sternal border
- increases: Valsalva (decreased venous return)
- decreases: rapid squatting
What is "pulsus parvus et tardus"?
= palpable pulse is lower than indicated by heart sounds
- can lead to syncope
- often a sign of aortic stenosis (age-related, bicuspid)
What type of heart condition is indicated by a wide pulse pressure? What murmur would you expect? Other symptoms?
- diastolic at aortic area (upper right sternal border)
- high-pitched, "blowing"
- increased by exhilation (left-sided)
- decreased by vasodilators (decreased afterload)
- other symptoms:
- head bobbing
- bounding pulses
What maneuvers increase the intensity of mitral valve prolapse?
- decreased venous return:
What maneuvers increase the intensity of mitral stenosis?
- increase in left atrium filling:
What would you suspect in a neonate with a continuous machine-like murmur? When would the murmur be loudest?
- congenital rubella
When does the most rapid ventricular filling occur?
just after mitral valve opens
When does the slowest ventricular filling occur?
just before mitral valve closes
During which phase of the cardiac cycle does the most O2 get consumed?
What makes cardiac muscle contraction different from skeletal muscle contraction?
- 1. AP plateau: Ca2+ influx
- 2. gap junctions: electrical coupling
- 3. automaticity: If channels cause spontaneously depolarization in nodal cells during diastole
What respectively increases and decreases SA node conduction velocity (i.e. depolarization)?
- SA node conduction velocity = heart rate
- slope of phase 4 of pacemaker AP = heart rate
- catecholamines (adrenergic)
- Ach (PNS: muscarin)
- adenosine (vasodilator?)
What does a T-wave inversion indicate?
What causes a U wave? Where is it on an EKG?
U wave: hypokalemia, bradycardia
- EKG: after T wave and before P wave
- (i.e. between ventricular repolarization and atrial depolarization)
What are common features of people born with congenital prolonged QT syndromes?
- dysfunctional cardiac potassium and/or sodium channels
- predisposed to torsades de pointes (VT, Vfib)
- severe congenital sensorineural deafness (Jervell/Lange-Nielsen syndrome)
What is torsades de pointes and its causes?
- torsades de pointes = ventricular tachycardia characterized by shifting sinusoidal waveforms on ECG
- predisposes to ventricular fibrillation
- causes: anything that prolongs QT
- congenital prolonged QT syndrome
- Type III antiarrythmics (e.g. amiodarone)
What drugs are useful in treating atrial fibrillation?
What drugs are useful in treating atrial flutter?
- Type IA
- Type IC
- Type III
definitive treatment: convert to sinus rhythm
What infectious disease may result in 3rd degree heart block? What would you expect on ECG? How would you treat the heart condition?
Lyme Disease: Borrelia burgdorferi (tick)
- 3rd degree heart block:
- independent beating of atria and ventricles
- no relation between P waves and QRS complexes
- atrial contraction faster than ventricular contraction
What are the ECG features of V-fib and how would you treat it?
- completely erratic rhthym
- no identifiable waves
- can be fatal
What are the main features of ANP?
ANP = atrial natriuretic peptide = diuretic from atria
- ANP increased by:
- increased blood volume
- increased atrial pressure
- dilates afferent arteriole/constricts efferent arteriole via cGMP
- causes diuresis
- "escape from aldosterone"
What is the "Cushing Triad" and what causes it?
- Cushing Triad:
- respiratory depression
- cause: central chemoreceptor response (pH, PCO2)
- increased intracranial pressure: constricts arterioles: cerebral ischemia: SNS response: hypertension: reflex bradycardia
What are the differences between the peripheral and central chemoreceptors?
- detect PO2, some PCO2, and pH
- arteriolar blood content
- detect PCO2 and some pH
- brain interstitial fluid
What are the basic ECG features of atrial fibrillation?
- 1. no P waves
- 2. irregularly irregular baseline
- 3. irregularly spaced QRS complexes
What are the basic ECG features of atrial flutter?
- 1. "sawtooth" flutter waves
- 2. back-to-back P waves
What are the basic ECG features of 2nd degree heart block Type I?
- 1. progressively prolonged PR intervals result in a "dropped" P wave
- 2. usually asymptomatic
What are the basic ECG features of 2nd degree heart block Type II?
- 1. "dropped" P wave without any progressive lengthening of PR interval
- 2. usually a 2:1 distribution (2 P waves: 1 QRS complex)
- 3. can lead to 3rd degree heart block
What are the basic ECG features of ventricular fibrillation? How is it treated?
- 1. completely erratic rhythm
- 2. no identifiable waves of any kind
- 3. can be fatal
How is the O2 demand of the heart maintained?
coronary blood flow
(can't increase extraction rate because already 100%)
What factors determine blood flow autoregulation in the heart?
What factors determine blood flow autoregulation in the brain?
What factors determine blood flow autoregulation in the skeletal muscle?
How are the CV responses to hypoxia different in the lung versus other tissues?
lung hypoxia: causes vasoconstriction to shunt blood for ventilation/perfusion match
hypoxia in other tissues: causes vasodilation
What are common mechanisms of edema and their causes?
- 1. increased capillary pressure: heart failure
- 2. decreased plasma proteins: nepthrotic syndrome, liver failrue
- 3. increased capillary permeability: toxins, infections, burns
- 4. increased interstitial fluid colloid osmotic pressure: lymphatic blockage
What are common causes of early cyanosis?
- right-to-left shunts:
- tetralogy of fallot
- truncus arteriosus persistance
- Tricuspid atresia
- Total anamolous pulmonary venous return (TAPVR)
What are the features of Tetralogy of Fallot? Which is most important for prognosis?
- 1. pulmonary valve stenosis (most important for prognosis)
- 2. RVH
- 3. VSD
- 4. overriding aorta
cause: anterosuperior displacement of infundibular septum
- early cyanosis (blue baby)
- cyanotic "spells"
- squatting helps cyanosis (increased TPR)
- X-ray: boot-shaped heart
What features are required to sustain life in a baby with TGA?
- right-to-left shunt required for blood mixing:
- patent foramen ovale
most infants die without immediate surgical correction
What valvular disruption is common with coarctation of the aorta?
What is a potential cause of differential cyanosis (i.e. lower extremity cyanosis)?
Why is a PDA normal in fetal life but not neonate life?
- fetal: PDA allows right-to-left shunt which is normal
- neonate: PDA switches to left-to-right shunt which is abnormal
What congenital abnormalities are associated with 22q11 syndromes?
- Truncus arteriosus
- Tetralogy of Fallot
What congenital abnormalities are associated with Down's syndromes?
- endocardial cushion defects (AV septal defect)
What congenital abnormalities are associated with congenital rubella?
- pulmonary artery stenosis
- septal defects
What congenital abnormalities are associated with Turner syndromes?
(preductal) coarctation of aorta
What congenital abnormalities are associated with Marfan's syndromes?
aortic insufficiency (late)
What congenital abnormalities are associated with diabetic mothers?
transposition of great arteries
Which skin cell is involved with xanthomas?
lipid-laden histiocytes in skin
What are the most sites for atherosclerosis?
abdominal aorta > coronary artery > popliteal artery > carotid artery (> Circle of Willis?)
What cytokines are involved in atherosclerosis formation?
What is the progression of atherosclerosis development?
- 1. endothelial dysfuction
- 2. macrophage and LDL accumulation
- 3. foam cell formation
- 4. fatty streaks
- 5. smooth muscle cell migration (TGF-b, PDGF)
- 6. fibrous plaque
- 7. complex atheromas
What are the different associations between thoracic and abdominal aortic aneurysms?
- thoracic aneurysm association:
- cystic medial necrosis (Marfan's)
- abdominal aneurysm association:
What are the key features of aortic dissection?
longitudinal intraluminal tear: false lumen
- s/s: tearing chest pain radiating to back
- CXR: mediastinal widening
- CT: false lumen within aorta
What is coronary steal syndrome?
= when a vasodilator aggravaes ischemia by shunting blood from an area of critical stenosis to an area of higher perfusion
What is the most common cause of myocardial infarction?
acute thrombosis: coronary artery atherosclerosis
What is the most common case of sudden cardiac death?
- (death within 1 hour of symptoms)
- lethal arrythmia: V-Fib
What are the most likely occluded coronary arteries?
LAD > RCA > CFX
What are common ECG changes for subendocardial infarct vs transmural infarct MI?
- subendocardial infarct:
- ST depression
- transmural infartct:
- pathologic Q waves
- ST elevation
What are common causes of dilated cardiomyopathy?
- alcohol abuse
- beri beri
- cocaine abuse
- Chagas' disease
- Coxsackie B virus myocarditis
- Doxorubicin toxicity
Which cardiomyopathies reflect diastolic dysfunction?
Which drugs improve mortality with CHF?
- ACE inhibitors
- angiotensin receptor antagonists
What type of hypersensitivity reaction is rheumatic fever?
Type II hypersensitivity: antibodies to M protein
Which conditions are associated with fibrinous pericarditis?
- Dressler's syndrome
Which conditions are associated with serous pericarditis?
- noninfectious inflammatory diseases:
- rheumatic fever
What is pulsus paradoxus? What conditions is it associated with?
= when systolic BP drops >10 mmHg during inspiration
- severe cardiac tamponade
- obstructive sleep apnea
What are the features of cardiac tamponade?
= compression of heart by fluid within pericardium
- increased HR
- pulsus paradoxus
- increased JVP
- distant heart sounds
- equalization of diastolic pressure in all chambers
What are the associations of rhabdomyomas?
- most common primary cardiac tumor of children
- associated with tuberous sclerosis
What are the associations of myxomas?
- most common primary cardiac tumor in adults
- 90% in atria (esp. left)
- "ball-valve" appearance on CT
- multiple syncopal episodes
- Kussmaul's sign: increased JVP with inspiration
What are common original tumors that metastasize to the heart?
What are examples of large-vessel vasculitis and their general age of presentation?
- temporal/giant cell arteritis (elderly women)
- Takayasu's arteritis (Asian women <40yo)
What are examples of medium-vessel vasculitis and their general age of presentation?
- polyarteritis nodosum (young adults)
- Kawasaki's disease (Asian <4yo)
- Buerger's disease (heavy smokers, males <40yo)
What are examples of small-vessel vasculitis and their associated antibody?
- microscopic polyangiitis (p-ANCA)
- Wegener granulomatosis (c-ANCA)
- Churg-Strauss syndrome (p-ANCA)
- Henoch-Schonlein purpura (IgA)
- Sturge-Weber disease
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