-short PR interval (ventricles contracts sooner, AV valves slam shut) -high CO or tachycardia -valve leaflets have increased mass (scarred or redundant prolapsing mitral valve)
What makes S1 softer?
-long PR interval (valves float back to closed) -mitral regurg -decreased leaflet mobility from scarring/stenosis -noncompliant LV (high diastolic pressure precloses leaflets)
Where's the only place you'll hear S2?
pulmonic area (L 2nd intercostal space)
What makes S2 louder?
-arterial HTN -leaflets have increased mass -increased pulm blood flow (S2)
What makes S2 softer?
-decreased mobility in severe valvular stenosis -calcification of aortic valve
What are some causes of abnl splitting of S2?
-widened splitting (electrical/mech delay of RV delays P2; split during expiration AND inspiration) -fixed splitting (ASD increases R heart filling, delays P2) -paradoxical splitting (electrical/mech delay of LV so A2 after P2)
What are ejection clicks?
hearing semilunar (aortic or pulm) valves open
When will a pulmonary ejection click get softer?
Where are ejection clicks heard best?
L sternal border (2nd intercostal space)
What's the etiology of ejection clicks?
-congenitally stenotic semilunar valves -dilated aorta or PA
What are nonejection clicks?
hearing mitral or tricuspid valves continuing to move (tense) during systole b/c they are prolapsed
What are opening snaps?
hearing mitral or tricuspid valves open
Where are opening snaps heard best?
lower L sternal border or apex
What causes opening snaps?
scarring and fusion of leaflets d/t rheumatic heart disease
What is S3?
low pitched sound heard d/t increased early diastolic ventricular filling or dilated, poorly functioning ventricles
-flow across partial obstruction (valvular stenosis, hypertrophy, narrowed blood vessel) -increased flow across nl structures -ejection into dilated vessel (least common) -abnl flow when valve doesn't close -abnl communication b/w high and low pressure chambers or vessels (congenital defects)
What would cause increased flow across nl structures?
Characteristics of pathologic systolic ejection murmur:
-crescendo decrescendo -after S1 (gap d/t isovolumetric contraction) -grade 3 or 4 -heard at R sternal border - 2nd intercostal space (aortic) or L sternal border - 2nd intercostal space (pulmonic)
Characteristics of physiologic systolic ejection murmur:
-grade 1 or 2 -best heard in aortic or pulmonic areas -decreases when you're upright (SV goes down)
What causes a pansystolic murmur?
leaky valve (mitral or tricuspid regurg) or VSD
Characteristics of pansystolic murmur:
-continuous b/w S1 and S2 -caused by large pressure diff -high pitched (best heard w/ diaphragm) -grade 2 thru 4
What causes a late systolic murmur?
prolapse of mitral valve leaflets during late systole --> regurg
Characteristics of late systolic murmur:
-preceded by at least 1 nonejection click
What causes a diastolic decrescendo murmur?
aortic or pulmonic valve regurg d/t severe pulm HTN
Characteristics of diastolic decrescendo murmur:
-decrescendo b/c pressure diff gradually decreases -begins right after S2 -heard best at L sternal border w/ diaphragm (high pitched)
What causes a mid-late diastolic murmur?
mitral or tricuspid valve stenosis (partially obstructed flow)
Characteristics of mid-late diastolic murmur:
-after S2 (gap d/t isovolumetric relaxation) -preceded by opening snap -low pitched (heard w/ bell at apex for mitral or LLSB for tricuspid) -crescendo right before systole d/t atrial contraction
What causes a middiastolic low pitched murmur?
-pulmonic valve regurg -high early diastolic flow across mitral or tricuspid valves (severe regurg) -preclosure of mitral valve by severe aortic regurg (Austin Flint)
What causes a continuous murmur?
communication b/w high and low pressure chamber/vessel where pressure diff maintained throughout systole and diastole (turbulent flow always in 1 direction) -PDA
Characteristics of continuous murmur:
-heard best at L sternal border - 2nd intercostal space -gets loudest around S2
What causes to and fro murmurs?
combo of stenosis and regurg at any valve
What type of murmurs increase w/ inspiration?
What murmurs increase w/ leg raising?
What murmurs get louder after long R-R interval?
How long is a nl PR interval?
What would cause an abnl PR interval?
short: abnl connection b/w atria and ventricles long: delayed conduction thru AV node
How long is a nl QRS interval?
less than 120 msec
What would cause a short QRS interval?
abnl sequence of ventricular depolarization or increased ventricular mass
How long is a nl QT interval?
less than half the RR interval
What would cause a prolonged QT interval?
delayed ventricular repolarization (puts you at risk for torsade)
What EKG leads look at inf wall of the heart?
II, III, aVF
What EKG leads look at the septum?
What EKG leads look at the ant wall LV?
What EKG leads look at LV (lateral)?
I, aVL, V5, V6
How do you calculate HR from EKG?
HR = 300 / # of big boxes b/w beats for irreg HR... HR = # of beats across EKG x 6
What is the range of the nl QRS axis?
-30 degrees to +90 degrees
What is the QRS axis?
avg direction of electrical activity in heart during ventricular depolarization (measured in frontal plane)
Quadrant Approach to QRS axis:
Lead I pos, Lead aVF pos --> Normal Lead I pos, Lead aVF neg --> could be nl or L axis deviation (look at Lead II - if QRS pos, it's nl; if QRS neg, it's L axis deviation) Lead I neg, Lead aVF pos --> R axis deviation Lead I neg, Lead aVF neg --> extreme deviation
Equiphasic Approach to QRS axis:
What lead has most equiphasic QRS complex? Which lead is 90 degrees away from this lead? If QRS complex in 2nd lead is pos, direction of this lead approximates QRS. If it's neg, QRS axis is 180 degrees away.
What EKG findings suggest R atrial enlargement?
P wave axis shifted R of +75 degrees P wave taller than 2.5 mm (lead II) R atrial part of P wave bigger than 1 small box (V1)
What EKG findings suggest L atrial enlargement?
P wave axis shifted L of +30 degrees P wave greater than 120 msec w/ 2 peaks (lead II) L atrial part bigger than 1 small box (V1)
What changes happen to QRS complex in leads V1 and V6 w/ ventricular hypertrophy?
RVH: QRS is inverse of nl LVH: QRS more exaggerated than nl
What secondary repolarization abnormality happens in ventricular hypertrophy?
downsloping ST segment and T wave inversion
What are the diagnostic criteria for LVH?
S wave (V1) + R wave (V5 or V6) greater than 35 mm R wave (V5 or V6) greater than 26 mm
What are the diagnostic criteria for R bundle branch block?
QRS duration greater than 120 msec M shaped QRS complex (V1) prominent S wave in leads I and aVL secondary repolarization abnormalities in V1 and V2
What are the diagnostic criteria for L bundle branch block?
QRS duration greater than 120 msec Broad R wave in leads I, aVL, V6 Lack of q waves in I and V6 ST depression and inverted T wave (I, aVL, V6) deep S wave, upsloping ST elevation, prominent T wave (V1, V2, V3)
How long are incomplete bundle branch blocks?
What are the etiologies of RBBB?
-CAD -pulm HTN -acute PE -idiopathic -iatrogenic during R heart cath -CHD
0: upstoke d/t opening of fast Na channels 1: dip d/t Na channel inactivation and transient K efflux 2: plateau d/t Ca influx 3: repolarization d/t closed Ca channels and increased K conductance 4: resting, determined by K
Equation for cardiac output:
CO = HR x SV
Equation for stroke volume:
SV = end diastolic volume - end systolic volume
Equation for ejection fraction:
EF = (end diastolic - end systolic) / end diastolic volume x 100 Nl is 55-75%; heart failure is less than 40%
Tension = chamber blood pressure x radius / 2 x wall thickness
What factors affect myocardial O2 consumption?
-HR -contractility -wall tension
What differentiates cardiac muscle from skeletal muscle?
-central nuclei -branching -intercalated discs -T tubules at Z discs
Blood vessel layers:
Intima - endothelium and subendothelial collagen Media - int elastic layer, smooth muscle cells, elastic fibers, ext elastic layer Adventitia
Types of capillaries:
Continuous - transport occurs by diffusion and caveolae Fenestrated - found in glomerulus and intestine, have cytoplasmic pores Discontinuous - found in liver and spleen, have gaps in basement membrane
Layers of trachea:
Mucosa - resp epithelium, loose CT, lympathics Submucosa - dense CT, smooth muscle, mucous and serous glands Cartilaginous - C shaped rings of cartilage Adventitia - loose CT
Layers of bronchi:
Mucosa - resp epithelium (basal lamina now has 3 layers), loose CT, lymphatics Submucosa - dense CT, smooth muscle, glands Cartilaginous - irreg shaped cartilage plates Adventitia - connects to accompanying branch of pulm a
Where's the last place in the airway Goblet cells, glands, and hyaline cartilage are found?
Where's the last place in the airway ciliated cells are found?
What are the ways CO2 is transported in the blood?
-dissolved -bound to Hb -as HCO3
What are the nl O2 sats for the heart chambers and great vessels?
R heart and pulm a: 70-80% L heart, pulm veins, pulm capillary wedge: 93-100%
What is the Fick method?
CO = O2 consumption / arteriovenous O2 diff
Equation for pulm vascular resistance:
PVR = mean pulm a pressure - LA pressure/CO x 80 Nl: 20-130
Equation for systemic vascular resistance:
SVR = MAP - RA pressure/CO x 80 Nl: 700-1600
What roles do diff areas of the brainstem play in ventilation?
Medulla: rhythm of breathing Apneustic (pons): unclear; if transected, long inspiratory gasps Pneumotaxic (pons): fine tuning of breathing
What do central chemoreceptors (medulla) respond to?
pH of CSF More impt in controlling ventilation
What do peripheral chemoreceptors (carotid and aortic bodies) respond to?
R increases w/ a carb heavy diet and decreases w/ a fat heavy diet
Alveolar Air Equation:
PaO2 = FiO2 (Pb - 47) - PaCO2/R R is usually 0.8
What's the value for nl Tidal Volume and what are its components?
Vt = 500 mL Anatomic dead space = 150 mL Alveolar air = 350 mL VT = VD + VA
What are the values for nl minute ventilation and alveolar ventilation?
Minute ventilation = 7500 mL / min Alveolar ventilation = 5250 mL / min
Equation for minute ventilation:
VE = RR (VA + VDS)
What factors contribute to lung compliance?
Characteristics of lung -stiffer w/ scarring/fibrosis, pneumonia, pulm edema -stretchier w/ emphysema, aging Lung volume Surface Tension - smaller alveoli want to collapse and push their air into bigger alveoli *counteracted by surfactant
What factors determine airway resistance?
-size and numbers (mostly medium bronchi) -lung volume -smooth muscle constriction -density and viscosity of inspired gas
What is the equal pressure pt?
when intrapleural pressure becomes greater than pressure inside the airway