Cardio Flashcards
Memorize cardio physiology, ddx, and cardiovascular drugs
List 12 causes of sinus bradycardia
- Hypothermia
- Hypothyroidism
- Cardiac arrest (before or after arrest)
- Drugs (tranquilizers, anesthetics, beta-blockers, calcium- channel blockers, digoxin)
- Increased ICP
- Brainstem lesion
- Severe metabolic disease (uremia, hyperkalemia)
- Ocular pressure
- Carotid sinus pressure
- High vagal tone (eg, lower airway dz, pharyngeal dz, GI obstruction)
- Sinus node disease
- Normal variation (athletic dog)
List 15 causes of sinus tachycardia
- Hyperthermia/fever
- Hyperthyroidism
- Anemia/hypoxia
- Heart failure
- Shock
- Hypotension
- Sepsis
- Anxiety/fear
- Excitement
- Exercise
- Pain
- Drugs (anticholinergics, sympathomimetics)
- Toxicities (chocolate, hexachorophene)
- Electrical shock
- Other causes of high sympathetic tone
What percentage of total blood volume is in the systemic circulation and how is it distributed between the veins, arteries, and capillaries?
75% of TBV
80% veins
15% arteries
5% capillaries
What percentage of total blood volume is in the pulmonary circulation?
25%
Where do the left and right coronary arteries arise from?
sinuses of Valsalva (behind aortic valve leaflets to myocardium)
The RV wall is usually ____ the LV wall.
1/3 as thick as..
What are the normal pressures (mm Hg) in the heart?
RA: 0-5 (mean)
RV: 15-30 (systolic), 0-5 (end-diastolic)
PA: 15-30 (systolic), 5-15 (diastolic), 10-20 (mean)
LA: 4-12 (mean)
LV: 90-120 (systolic), 4-12 (end-diastolic)
Aortic: 90-150 (systolic), 60-100 (diastolic), 70-100 (mean)
List 10 cardiac causes of supraventricular arrythmias
Mitral or triscuspid insufficiency DCM HCM Restrictive cardiomyopathy Cardiac neoplaia Congenital malformation Accessory AV nodal bypass tract (s) Myocardial fibrosis High sympathetic tone Digitalis glycosides Other drugs (anesthetics, bronchodilators) Ischemia Intraatrial catheter placement
List 5 extracardiac causes of supraventricular arrhythmias
catecholamines electrolyte abnormalities acidosis/alkalosis hypoxia thyrotoxicosis severe anemia electric shock thoracic surgery
List 10 cardiac causes of ventricular arrhythmias
CHF Cardiomyopathy (Doberman/Boxer) Myocarditis Pericarditis Degenerative valve dz with myocardial fibrosis Ischemia Trauma Cardiac neoplasia Heartworm disease Congenital heart disease Ventricular dilation Mechanical stimulation (catheter/wire) Drugs (digitalis, sympathomimetics, anesthetics, tranquilizers, anticholinergics, antiarrhythmics)
List 15 extracardiac causes of ventricular arrhythmia
Hypoxia Electrolyte imbalances (especially K+) Acidosis/alkalosis Thyrotoxicosis Hypothermia Fever Sepsis/toxemia Trauma (abdominal or thoracic) GDV Splenic mass or splenectomy HSA Lung dz Uremia Pancreatitis Pheochromocytoma Endocrine (Addison's, DM, hypothyroidism High sympathetic tone (pain, anxiety, fever) Central nervous system disease (increases in symp or vagal stimulation) Electric shock
List 7 effects of angiotensin 2
- vasoconstriction
- increased peripheral resistance
- increased mean circulatory filling pressure
- decreased Na and H2O secretion via direct renal effects
- increased aldosterone release
- stimulates thirst
- myocardial hypertrophy
Angiotensinogen is converveted to angiotensin I by what?
renin
Angiotensin I is converted to AT2 by what
ACE, in lungs
What is the main effect of ANP?
Diuresis and vasodilation, antagonizes the effects of ATII
How much desaturated hemoglobin is needed for cyanotic mucous membranes?
> 5 g/dl (50 g/L)
What is the normal vertebral heart score in dogs?
8.5-10.5
How do you determine if the cranial lobar vessels are enlarged on a thoracic lateral radiograph?
Compare the vessel diameter to where it crosses the 4th rib. The vessels should be no wider than 0.5-1X the diameter of the proximal 1/3rd of the rib
How do you determine if the caudal lobar vessels are enlarged on a thoracic VD radiograph?
Compare caudal lobar vessel to where they cross the 9th rib (dog) or 10th rib (cat). Normal is 0.5-1 x width of rib where they cross.
List 5 causes of a pulmonary undercirculation pattern.
- severe dehydration
- hypovolemia
- obstruction to RV inflow
- right sided CHF
- tetrology of Fallot
List 3 ways to determine caudal vena cava enlargement in dogs with radiographs.
- CaVC/aorta diameter at same ICS > 1.5
- CaVC/length thoracic vertebrae directly above tracheal bifurcation >1.3
- CaVC/width right 4th rib > 3.5
List the standard bipolar leads.
I: RA (-) –> LA (+)
II: RA (-) –> LL (+)
III: LA (-) –> LL (+)
How do you determine HR on ECG?
3000/# small boxes R-R (50 mm/s)
1500/# small boxes R-R (25 mm/s)
What is a wandering pacemaker?
Cyclic change in p wave configuration related to a shift in pacemaker location.
What is a sinus arrhythmia?
Faster HR during insp, slower during exp, normal d/t vagal tone.
What is the definition of sinus arrest?
Pause in sinus activity lasting at least twice the duration of the normal R-R interval.
What is a Mobitz I second degree AV block?
Progressive PR prolongation before a dropped beat. Ddx: AV node dysfxn, high vagal tone
What is a Mobitz II second degree AV block:
Uniform PR intervals before blocked impulses, lower AV dz (bundle of His or major BB)
What is the normal rate for ventricular escape rhythm?
40-50 bpm (dog), < 100 (cat)
What is the normal rate for a junctional escape rhythm?
40-60 (dog)
How do you estimate the MEA?
- Lead with the largest R wave (+ direction is the est MEA)
2. Isoelectric, then perpendicular, + or - = MEA
What is normal MEA?
+40 to +100 (dog), 0 to +120 (cat)
What is p mitrale?
Wide, notched p waves = LA enlargement
What is p pulmonale?
Tall p waves = RA enlargement
List 5 differentials for small voltage QRS.
- Pleural or pericardial effusion
- Obeisty
- Intrathorcic mass
- Hypovolemia
- Hypothyroidism
What are the ECG expectations with hyperkalemia?
- Tented +/- large t waves
- Abbreviated QT
- Flat/absent p wave
- Widened QRS
- ST depression
- Asystole, sinoventricular rhythm
Hyperkalemia is accentuated by the following:
Hypocalcemia, Hyponatremia, Acidosis
Hyperkalemia is counteracted by:
Hypercalcemia, Hypernatremia
Which organ in the body always receives the most blood flow?
Lungs
Whevever skeletal muscle blood flow increases, blood flow to other organs must decrease. T/F
F
A leaky aortic valve will cause what kind of murmur?
Diastolic
Slowing of action potential condunctino through the AV node will slow the heart rate. T/F
F
How are cardiac muscle cell action potentials different from skeletal muscle cells?
- They can be self-generating
- They can be conducted directly from cell to cell
- They have long durtion, which precludes fusion of individual twitch contractions
What is the effect of hyperkalemia and hypokalemia on the RMP?
Hyperkalemia decreases (less negative) the RMP, Hypokalemia increases (more negative) the RMP.
What are the effects of sodium channel blockers on the PR interval of the ECG? Duration of QRS complex?
Prolongs both
What are the effects of calcium channel blockers on the rate of firing of the SA nodal cells? Rate of conduction of the AP through the AV node? Myocardial contractility?
Decreases all
What are the effects of potassium channel blockers on action potential duration? On refractory periods?
Increases AP duration and refractor period
An increase in which of the following (with others held constant) will result in an increase in amout of active shortening of a cardiac muscle cell?
a. preload
b. afterload
c. contractility
preload and afterload
What happens when an intervention promotes early activation of the “delayed rectifier” K channel in cardiac muscle?
AP duration is decreased b/c activation of Ik initiates repolarization
Action potential conduction velocity in cardiac muscle tissue is influenced by all of the following except:
a. cell diameter
b. RMP
c. Extracellular K concentration
d. Rate of rise (phase 0) of the AP
e. Duration of the plateau phase (phase 2) of the AP
e
The primary route of removal of calcium fromt eh sarcoplasm during relaxation of a cardiac muscle cell is by:
Active transport into the SR
What cardiovascular factors increase NT-proBNP?
- Heart failure
- Ischemia
- Arrhythmia
- Valvular heart disease
- Hypertension with LVH
- Asymptomatic LV dysfxn
List 10 noncardiac factors that can increase NT-proBNP.
- PTE
- Cor pulmonale
- Sepsis
- Pulmonary hypertension
- Hyperthyroidism
- Kidney failure
- Lung tumors
- Intracerebral hemorrhage
- Advanced liver disease
- Excessive cortisol levels
- Sleep apnea
What is the definition of a biomarker?
A characteristic that is objectively measured and evaluated as an indicator of normal biologic processes, pathogenic processes, or pharmacologic responses to therapeutic intervention.
What are some examples of biomarkers of myocyte injury?
Troponin I, troponin T, creatinine kinase isoenzymes
What are some examples of biomarkers of myocyte stress?
Natriuretic peptides, adrenomedullin, mid-regional proadrenomedullin, ST2
What are some biomarkers of cardiac remodeling?
MMPs 1, 2, 7, 8, 9
Tissue inhibitors of metalloproteinases
Procollagen type III amino terminal peptide
What are some biomarkers of endothelial dysfunction?
Flow mediated dilation (FMD), p-selectin, soluble ICAM-1, vascular adhesion protein 1, asymmetric and symmetric dimethylarginine, vWF, l-arginine, NO metabolites
What are some biomarkers of inflammation?
CRP
IL -1, 6, 10
TNF alpha
What are some neurohormonal biomarkers?
natriuretic peptides, endothelin-1, big endothelin-1
BNP is released in response to what? from where?
volume expansion and pressure overload, from ventricular myocytes
List at least 6 physiological functions of BNP
Natriuresis, diuresis, vasodilation, inhibition of sympathetic tone, inhibition of the RAAS, inhibition of endothelin-1, inhibition of myocardial hypertrophy, inhibition of smooth muscle proliferation, altered vasosympathetic balance, inhibition of bronchoconstriction, lusitropy, gastric emptying and absorption, potential central effects (thirst inhibition, decreased salt appetite, inhibtion of ACTH and vasopressin)
From the pilot study by Prosek et al on azotemia and serum NTproBNP, their findings showed BNP is not affected by renal dysfunction. T/F
False. Renal dz increased NTproBNP. With indexed with BUN or creatinine (NTproBNP:BUN or :creat), the effect of renal dysfxn removed.
Which of the following was associated with higher cTnI in patients undergoing cardiac catheterization procedures (Shih, 2009)?
a. difficulty of procedure
b. amount of contract injected
c. length of procedure
d. difficulty of anesthesia
c. length of procedure
Which of the following cardiac cath procedures led to the largest increase in cTnI (Shih, 2009)?
a. Balloon valvuloplasty
b. Pacemaker implantation
c. PDA coil embolization
b. pacemaker (* increased at 4, 240, and 10 d after procedure)
Brady, JVECC, 2004, Na and Glucose CHF found which three things statistically different in survivors vs. nonsurvivors.
- NS had lower sodium
- NS had higher glucose
- NS had lower medial rectal temp
What are the 3 theories for hyperglycemia in CHF?
- Impaired insulin-mediated glucose uptake
- Defects in insulin signal transduction
- Insulin receptor antagonism
What is normal DO2 in a dog?
823 ml/min/m2
What is normal VO2 in a dog?
166 ml/min/m2
What is normal oxygen extraction ratio in a dog?
20.5%
What is normal venous admixture in a dog?
2.8-4.4%
Prognosis is less than 50% if cats present with a rectal temperature less than ___ on presentation with ATE.
37.2 C (98.9 F)
72% cats with ATE fit this category on presentation
What percentage of cats with HCM will develop ATE.
21%
What is the median age of cats with ATE.
8-9 y
What percentage of cats have history of heart disease on presentation with ATE?
<12%
What percentage of cats will have normal thoracic auscultation on presentation with ATE?
40%
Reported avg survival in ATE cats is?
51-350 d
What percentage of cats treated for ATE will have recurrence?
17-50%
List 5 antithrombotic factors of normal endothelium.
- antithrombin
- thrombomodulin
- tPA
- prostacyclin (PGI2)
- nitric oxide
From the MacDonald et al paper on echocardiographic pericardial effusion paper, what is the sensitivity and specificity of echo for detection of a RA mass?
82% sensitivity, 99% specificity
What were the most common ECG abnormalites from the MacDonald pericardial effusion paper?
- electrical alternans (28%)
- Dampened QRS (24%)
- Ventricular arrhythmia (13%)
What echo view gives the best view of the right atrium?
Left cranial parasternal long-axis view
What is the difference in MST for neoplastic vs. nonneoplastic causes of pericardial effusion?
cancer 26-56 d
no cancer 790-1068 d
From the MacDonald paper on pericaridal effusion, all of the following are true except:
a. 30% of dogs with cardiac HSA had splenic HSA
b. All dogs with LSA had metastatic disease
c. Dogs with masses were significantly older than dogs w/o masses (9.7 y vs 7.9 y)
d. A globoid heart was seen on radiogaphs in 90% of cases
d. A globoid heart was only seen in 52.3% of dogs, making this a poorly sensitive diagnostic test for pericardial effusion
Pericardial fluid analysis identified the cause of pericardial effusion in 80% of cases (MacDonald, 2009). T/F
F - 12.8%, only those with infective pericarditis and lymphoma
The rate of bicavitary effusion, pleural effusion, or ascites did not differ between neoplastic causes and idiopathic pericaridits (MacDonald, 2009). T/F
T
What percentage of cats were hypercoagulable (based on factor excess, inhibitor deficiency, or thrombin generation) in cats with smoke vs. ATE (Stokol, 2008, JVIM)?
50% smoke, 56% ATE
Which of the following was significantly higher in ATE cats (Stokol, 2008, JVIM)?
a. fibrinogen
b. vWF:Ag
c. thrombin-antithrombin complex
d. d-dimers
b. vWF:Ag - reflective of endothelial damage from occlusive thrombus
What makes up Virchow’s triad?
- Endothelial injury
- Blood flow abnormalities
- Hypercoagulability
Left atrial size was found to be a risk factor for ATE in the Stokol, JVIM, 2009 paper. T/F
F
Left atrial size was found to be a risk factor for hypercoagulability in the Stokol, JVIM, 2009 paper. T/F
F - left atrial size not associated with hypercoagulability or increased risk of ATE
Rank the following in most common to least commonly documented with hyperkalemia in the JVECC, 2008 paper, Tag, et al. hyponatremia hypochloridemia hypermagnesemia hypocalcemia venous acidemia
- venous acidemia (94%)
- hypermagnesemia (67%)
- hyponatremia (49%)
- hypochloridemia (40%)
- hypocalcemia (20%)
How does hypocalcemia affect the action potential?
Prolongs phase 2 and is postulated to down-regulate myocardial B-receptors causing weakness of the cardiac muscle.
What is the effect of hypocalcemia on the ECG?
Prolongation of the the S-T segment and Q-T interval.
How does hypocalcemia enhance cardiotoxicity of hyperkalemia?
Lowers the cell’s threshold potential, the resting membrane potential is elevated during hyperkalemia, further exacerbating the cell’s hyperexcitability.
What are the ECG abnormalities associated with hypermagnesemia?
Prolonged QRS, shortened QT, prolonged PR
List 5 causes of peaked T waves.
- Bradycardia
- Cerebrovascular accidents
- LV diastolic overload
- Subendocaridal ischemia
- Hypothermia
- Death
List 5 causes of wide QRS complexes:
- Increased parasympathetic tone
- Hypoglycemia
- Hypothermia
- Hypothyroidism
- Drugs (digoxin, propranolol)
List 5 factors that influence the difference between ScvO2 and SvO2. (Vincent, Crit Care, 2011)
- Sampling site of central venous blood
- L–> R shunts
- Incomplete mixing of venous blood
- Oxygen extraction in renal and splanchnic beds
- Redistributino of blood flow through upper and lower body
- Level of consciousness
- Myocardial VO2
What is the Bernolli equation derivation to convert velocity to pressure gradient?
Pressure gradient = 4 x velocity squared
What is the formula for fractional shortening?
(LVIDd-LVIDs)/LVIDd x 100%
Pro-BNP is cleaved to cBNP and NT-proBNP by….
corin
cBNP binds to what receptor
NPRa
cBNP was sinificantly increased in all dogs with CHF compared to other groups with a mean value of? (Lee, JVECC, 2011)
4.2 pg/mL
What percentage of dogs w/o CHF had cBNP value over 4.2 pg/mL (Lee, JVECC, 2011)
21%
What was the interassay and intraassay coefficient of variation for the cBNP test (Lee, JVECC, 2011)?
9.41% and 7.79%, respectivly
Spontaneous echocardiographic contrast (“smoke”) is thought to be directly proportional to ___ and ___ and inversely related to ____.
HCT and fibrinogen, shear rate (flow)
What is the best echo view to assess for heart based tumor?
Long and short axis RIGHT cranial position
What is the best echo view to valuate the right auricle?
tilted LEFT cranial view
List the bradyarrhythmias requiring emergency intervention.
High-grade 2nd degree AV block Complete (3rd degree) block Sinus arrest (SSS) Persistent atrial standstill Asystole
List 3 indications for a temporary pacemaker.
- Not stable enough to transfer
- Intoxications (short term pacing)
- To assess end organ dysfxn before perm pacemaker
Which side should a temporary pacemaker be placed on?
left jugular
What is output on PACE generator?
strength of pacing impulse (mA)
What should the output be set at?
2-3X the lowest output determined to capture the heart
What is sensitivity on PACE generator?
how well the pacemaker senses the intrinsic electrical activity (mV); higher mV means lower sensitivity
What is the most common complication of temporary pacemaker?
Loss of capture
List complications of long term pacemaker.
Lead dislodgement Arrhythmia during placement Seroma over generator Infection Programming difficulties
CC CPR results in ___ % normal blood flow to heart, and ____% normal flow to brain.
10-20%, 20-30%
What is the theory behind use of ITD during CPR?
Impedance of gas on INSPIRATION during the DECOMPRESSION phase of CPR would result in increased negative intrathoracic pressure and improve venous return to heart
What maneuver is the ITD based on?
Mueller maneuver
What is the cracking pressure of the ITD?
Pressure at which air flow is no longer impeded by the ITD (10-15 cm H20)
What are advantages to using ITD during CPR.
Improve preload Improve myocardial perfusion Decrease ICP Increase CPP Higher ROSC Better neuro outcome (humans)
What are contraindications of ITD?
pulm edema, CHF, < 10 kg
What do each of the subunits (C, T, I) of troponin bind?
C - calcium, T - tropomyosin, I - thin actin filaments
What are the sizes of cTnT vs. cTnI?
T - 37 kDa, I - 24 kDa (T elimination decreased in kidneys)
What breed possibly has higher cTnI than other breeds?
Greyhounds
What can falsely increase cTnI (according to manufacturer) - 3 things.
- severe hemolysis
- hemoconcentration >65%
- hyperglobulinemia
What was the main findings from Payne, JVECC, 2011 on cTnI in dogs presenting in resp distress to differentiate cardiogenic vs. non-cardiogenic?
Sign diff between normal, resp, and cardio. cTnI > 1.5 ng/ml sens 78%, spec 52%, so not recommended on its own
What was the main finding from Valverde, JVECC, 2011, comparing art pulse pressure waveform analysis to LiDCCO in dogs?
FloTrac/Vigileo (pulse pressure) OVERESTIMATED CO values compared to LiDCCO. Relative error was high (48 +/- 14%), so unreliable. Correlation acceptable (r=0.7). CO estimates throughout experiment 48-73% (avg 62%) higher than LidCCO
What is the difference between PiCCO and PulseCO?
Both are pulse contour CO monitors. PiCCO uses cold saline transpulm thermodilution to calibrate whereas PulseCO uses LiDCO as calibration
Arterial waveform is a product of:
stroke volume force (arterial peak before dichrotic notch) and elastic component of arteries, or Windkessel effect (area after the dicrotic notch)
Pulse pressure is proportional to ____ and inversely related to ______.
Stroke volume, aortic compliance