Cardiology Flashcards
(171 cards)
1
Q
When does isovolumetric contraction occur in the cardiac cycle?
A
Early ventricular systole.
Time from AV valve closure to opening of aortic/pulmonic valve, during which ventricular volume (EDV) remains unchanged
2
Q
How is stroke volume calculated?
A
EDV-ESV
3
Q
How is ejection fraction calculated?
A
SV/EDV
4
Q
When does isovolumetric relaxation occur in the cardiac cycle?
A
During early ventricular diastole
Time between closure of the aortic/pulmonic valve and opening of the AV valve, during which ventricular volume (ESV) remains unchanged
5
Q
Which structure is present in cardiomyocytes to permit flow of electrical impulses between cells?
A
Intercalated discs
6
Q
Binding of which ion to troponin C permits binding of actin/myosin in cardiomyocytes?
A
Calcium
7
Q
What is the term used to describe cardiac muscle contraction?
A
Cross-bridge cycling
8
Q
The distance between two Z-lines in cardiac muscle is known as a ____
A
Sarcomere
9
Q
How is cardiac output calculated?
A
CO= SV x HR
10
Q
What is the Frank-Starling mechanism?
A
Increased preload= increased contractility
11
Q
What is the Bainbridge Reflex?
A
Increased atrial stretch=increased HR
12
Q
Which adrenergic receptor is present on cardiomyocytes?
A
B1
13
Q
Describe the cellular cascade following binding of catecholamines to adrenergic receptors on the myocardium.
A
Gs protein-> increased cAMP-> PKA-> L-type Ca++ channels within T tubles open-> increased Ca++ release from SR
End result= increased contractility and HR
14
Q
Which cholinergic receptor is present on cardiomyocytes?
A
M2
15
Q
Describe the cellular cascade following binding of cholinergics to their receptors on the myocardium.
A
Gs-> decreased cAMP-> decreased intracellular Ca++
End result= decreased contractility and HR
16
Q
Mechanism of action of PDEIII in myocardial cells
A
Cleaves cAMP to reduce intracellular Ca++, reducing contractility
17
Q
How is blood pressure calculated?
A
BP= CO x SVR
18
Q
What is the Anrep effect?
A
Increase in afterload leads to increased contractility and decreased SVR (mediated by baroreflex)
19
Q
Where are the mechanoreceptors that mediate the baroreflex located?
A
Aortic arch and carotid body
20
Q
Describe the pathway involved in production of angiotensin II
A
Renin released from the JGA converts circulating angiotensinogen to ATI, which is converted to ATII via ACE (located in the lungs/tissue)
21
Q
Which angiotensin receptor mediates the classic effects of ATII?
A
AT1 receptor
22
Q
Effects of ATII on the kidneys (2)
A
- Increased Na+/H2O retention in the PCT
- Increased GFR via constriction of efferent renal arteriole
23
Q
Effect of ATII on the adrenal gland
A
Release of aldosterone which increases Na+/H2O reabsorption in the DCT
24
Q
Effect of ATII on the pituitary gland
A
Increased release of ADH which increases H2O reabsoption in the collecting duct (via V2 receptors)
25
Effect of ATII on peripheral vasculature
Vasoconstriction
26
Which second messengers are involved following activation of the AT1 receptor?
IP3/DAG
27
Which 3 factors regulate SVR?
1. Vasoconstriction (mediated via the sympathetic nervous system & ATII)
2. Cyclic nucleotides (CAMP/cGMP)
3. Local endothelial factors: endothelin, NO
28
Which channel is responsible for rapid depolarization (phase 0) in ventricular myocytes?
Rapid Na+ channels
29
Which channels are responsible for the plateau phase of the action potential (phase 2) in ventricular myocytes?
K+ (out) and L-type Ca++ (in)
30
Which channel is responsible for rapid repolarization (phase 3) in ventricular myocytes?
K+
31
Which ion is responsible for slow depolarization (phase 0) in sinoatrial myocytes?
Ca++
32
Which ion is responsible for rapid repolarization in sinoatrial myocytes?
K+
33
What are the two refractory periods in cardiomyocytes?
Absolute
Relative
34
When does the relative refractory period occur in ventricular cardiomyocytes?
End of phase 3 (repolarization)
35
What is the trigger for release of ANP/BNP?
Atrial/ventricular stretch
36
Name 3 non-cardiac causes of NT-proBNP elevations
Hyperthyroidism
Hypertension
Renal disease
37
Name three uses for NT-proBNP
1. Screening for cardiomyopathy (HCM, DCM)
2. Diagnosis of CHF: differentiating CHF and non-cardiac causes of respiratory signs
3. Prognosis of CVD
38
How does the heart remodel in response to pressure overload?
Concentric hypertrophy. Examples include aortic/pulmonic stenosis, hypertension, hyperthyroidism
39
How does the heart remodel in response to volume overload?
Eccentric hypertrophy. Examples include DCM, MMVD, aortic insufficiency, congenital shunts (PDA/septal defects)
40
What is the law of Laplace?
The tension on the wall of a chamber is the product of pressure x radius of the chamber
Wall stress= (pressure x radius)/(2 x wall thickness)
41
Which blood biomarker is an indicator of myocardial injury?
Cardiac troponin I
42
Which blood biomarker is an indicator of increased cardiac stretch?
NT-proBNP
43
Which of the following is an example of a class I antiarrhythmic:
Atenolol
Digoxin
Lidocaine
Amiodarone
Lidocaine
44
What is the mechanism of action of class I antiarrhythmics?
Na+ channel blocker
45
What is the mechanism of action of class II antiarrhythmics?
B blockers
46
Which anti-arrhythmic drug class does diltiazem fall under?
Class IV (Ca channel blocker)
47
What is the mechanism of action of digoxin?
Inhibits the Na/K ATPase, leading to increased intracellular Ca2+-> increased contractility. Also augments vagal tone to reduce HR
48
Low levels of which serum ion contribute to digoxin toxicity?
K+
49
Where in the nephron do loop diuretics exert their effects?
Thick ascending limb of the Loop of Henle. Inhibits Na/K/Cl cotransporter
50
Ototoxicity is an adverse effect of which class of diuretics?
Loop diuretics
51
What is the mechanism of action of spironolactone?
Aldosterone receptor blocker (acts in the collecting duct to reduce Na+ reabsorption); weak diuretic
52
What is the mechanism of action of hydrochlorothiazide?
Blocks Na/Cl in the distal convoluted tubule. Weak diuretic.
53
Which enzyme is inhibited by pimobendan?
PDE3-> increases cAMP in cardiomyocytes and cGMP in vasculature-> "inodilator"
54
Where are B2 receptors located and what is their effect?
Peripheral vascular beds of skeletal muscle. Vasodilation
55
T/F: epinephrine binds to all 4 adrenergic receptors while norepinephrine only binds to 3 (alpha-1/2, beta-1)
TRUE
56
Enalapril drug class
ACE inhibitor
57
Telmisartan drug class
Angiotensin receptor-1 blocker
58
At which stage of MMVD is treatment indicated?
ACVIM B2
59
What are the 4 (5) ACVIM stages for MMVD?
A: breed predisposition
B1: MR without LAE
B2: MR with LAE/heart enlargement
C: current or past CHF
D: refractory CHF
60
Name 3 breeds with a genetic predisposition towards DCM
Doberman
Great Dane
Irish Wolfhound
61
Which commonly used chemotherapeutic can induce DCM?
Doxorubicin
62
Which positive inotrope is commonly used in the treatment of occult DCM?
Pimobendan
63
Which gene is associated with ARVC in boxers?
Striatin
64
Which anti-arrhythmic is indicated for the management of ARVC in boxers?
Sotalol
65
Name 5 pathogens which can cause infectious myocarditis
Parvovirus
Distemper
Toxoplasmosis, Neosporosis
Fungal (cocci, blasto)
Bartonella
Leptospirosis
Leishmaniasis, Trypanosomas
Ehrlichia, borrelia
66
Which cardiomyopathy is most common in cats?
HCM
67
Name two common secondary causes of HCM in cats
Systemic hypertension
Hyperthyroidism
68
Name the 4 (5) ACVIM stages of feline cardiomyopathies
A: breed predisposition
B1: subclinical, no/mild LAE
B2: subclinical, moderate to severe LAE
C: current or past CHF/ATE
D: refractory CHF
69
Which gene is implicated in the development of HCM in Ragdolls and Maine Coones?
Myosin binding protein C (MyBPC3)
70
Systolic anterior motion of which valve can contribute to a dynamic ventricular outflow tract obstruction in cats?
Mitral valve (DLVOTO)
71
Which medication is indicated for the treatment of stage B2 feline HCM?
Antithrombotic therapy (clopidogrel)
72
Which form of RCM in cats is most common?
Myocardial (90%)>> endomyocardial (10%)
73
Name three signs of target organ damage (TOD) associated with systemic hypertension
Retinopathy (retinal detachment, hemorrhages)
Encephalopathy
Nephropathy (proteinuria, progressive CKD)
LV hypertrophy
74
What is the #1 predisposing factor for systemic hypertension in both dogs and cats?
CKD
75
Name three drugs used in the treatment of systemic hypertension
Amlodipine, telmisartan, ACE inhibitors
76
What is the most common congenital cardiac malformation in the dog?
PDA
77
Which form of PDA is associated with a better prognosis?
Funnel/tapering
78
Eisenmenger's syndrome
Increased pulmonary vascular resistance leading to reversal of a L-R shunt. Results in cyanosis, hyperviscosity syndrome
79
What type of murmur is classically associated with L-R shunting PDAs?
Continuous murmur due to shunting of blood during both systole and diastole
80
Treatment for L-R shunting PDAs
Surgical closure
81
Treatment for R-L shunting PDAs
Closure is contraindicated. Phlebotomy, hydroxyurea for tx of hyperviscosity
82
Most common congenital cardiac malformation in the cat
VSD
83
Define Ebstein's anomaly
Apical displacement of the tricuspid valve leaflests into the RV, associated with TV dysplasia
84
Which breed has a genetic predisposition for tricuspid valve dysplasia?
Lab
85
Which breed has a genetic predisposition for mitral valve dysplasia?
Bull Terrier (in combo with valvular aortic stenosis)
86
Which congenital cardiac malformation is associated with splintering or notching of the QRS complex on ECG?
Tricuspid valve dysplasia
87
What is the second most common congenital cardiac malformation in the dog?
Subaortic stenosis
88
What is the third most common congenital cardiac malformation in dogs?
Pulmonic stenosis
89
What is the recommended treatment for severe pulmonic stenosis?
Balloon valvuloplasty
90
What is the most common congenital cardiac malformation in large breed dogs?
Subvalvular aortic stenosis
91
Which gene is associated with the development of subaortic stenosis in the Newfoundland?
PICALM
92
Infective endocarditis is associated with which congenital cardiac malformation?
Aortic stenosis
93
What are the 4 morphological features of Tetralogy of Fallot?
1. RVOTO
2. RV hypertrophy
3. VSD
4. Dextroposition of the aorta
94
Which breed is predisposed to Tetralogy of Fallot?
Keeshond
95
Define pulsus paradoxus
Drop in artieral BP >10mmHg during inspiration. Associated with pericardial effusion
96
Classic ECG feature seen with pericardial effusion
Electrical alternans
97
What is the most common cause of pericardial effusion in cats?
CHF
98
What are the two general categories of pulmonary hypertension?
Pre-capillary and post-capillary pulmonary hypertension
99
Name 2 clinical signs which are strongly suggestive of pulmonary hypertension?
Syncope
Respiratory distress at rest
Respiratory distress with exercise
Right-sided CHF
100
What is the most common cause of pulmonary hypertension in dogs?
MMVD (left-sided heart disease)
101
Mechanism of action of sildenafil
PDE5 inhibitor (inhibits breakdown of cGMP in vasculature leading to vasodilation)
102
Sildenafil is contraindicated in which type of pulmonary hypertension?
Post-capillary/LHD
103
What is the PR segment?
Time between atrial/ventricular depolarization
104
What is the ST interval?
Time between ventricular depolarization and end of ventricular repolarization
105
What are the two broad drug classes used for treatment of preload problems?
Diuretics
Venodilators
106
What types of drugs are used for afterload problems?
Arteriodilators (e.g., ACEi, pimobendan, amlodipine, sildenafil for PH)
107
What is the most common clinical sign associated with infectious endocarditis?
Undulant fever
108
Name three broad consequences of infectious endocarditis
CHF
Embolization
Immunocomplex deposition
109
What is Virchow's triad?
Thrombus formation is promoted by blood stasis, hypercoagulability, and endothelial damage
110
What are the 5Ps of ATE?
Pain
Pallor
Pulselessness
Poikilothermia
Paralysis/paresis
111
T/F: hypothermia in an animal presenting with ATE is not associated with prognosis
FALSE- T <98.6F associated with <50% chance of survival
112
Which antithrombotic agent is recommended in cats with ATE?
Clopidogrel
113
Name 2 supraventricular tachycardias
Atrial fibrillation
Atrial tachycardia
114
Name one breed which is predisposed to idiopathic atrial fibrillation
Irish Wolfhound
115
Name two medications which can be used for the treatment of atrial fibrillation?
Diltiazem
Digoxin
116
Which of the following drugs would be inappropriate for the treatment of atrial tachycardia:
A) Diltiazem
B) Digoxin
C) Beta-blocker
D) Lidocaine
D) Lidocaine
117
Name 2 extracardiac causes of ventricular tachycardia
GDV
Pheochromocytoma
118
What is the difference between Mobitz type I and type II AV block?
Type I (Wenckebach): progressive lengthening of PR interval followed by complete block. Non-pathologic.
Type II: fixed PR interval with non-conducted beats. Associated with pathologic processes
119
Which metabolic disorder has been associated with AV block in dogs?
Hypothyroidism
120
What is the treatment of choice for high-grade 2nd or 3rd degree AV block?
Pacemaker
121
T/F: Severe hyperkalemia results in bradyarrhythmias (e.g., AV block, atrial standstill)
True
122
Tachycardia-bradycardia syndrome is seen with which bradyarrhythmia?
Sick sinus syndrome
123
Name one breed which is classically predisposed to sick sinus syndrome
West Highland Terrier
Cocker Spaniel
Mini Schnauzer
124
What are two types of pacemaker?
Epicardial
Transvenous
125
What are two forms of cardiogenic syncope?
- Hypotension inducing arrhythmia
- Structural heart disease with exertion OR hypotension-inducing arrhythmia
126
Name one type of neurocardiogenic syncope
Vasovagal
Tussive
Situational
127
Which phase of D. immitis microfilaria is transmitted to the host from the mosquito?
L3
128
How long does it take for a dog infected with D. immitis to begin to produce circulating microfilariae?
6-7 months
129
Where do adult heartworms live?
Pulmonary arteries
130
Name 2 consequences of heartworm infestation
PTE
Pulmonary hypertension
131
What is caval syndrome?
Adult HW extending into the RA/RV/vena cava leading to hemolysis, circulatory collapse
132
Which bacterial organism is commonly associated with heartworm infections?
Wolbachia
133
What is the first-line screening test for HW in dogs?
Antigen test
134
Which combination of tests should be used to diagnose HW in cats?
Antigen PLUS antibody test (due to immune-mediated destruction of circulating microfilariae)
135
What is the source of HW antigen detected on tests like the 4Dx?
Female adult worm uterine proteins
136
If you get a positive HW result on 4Dx in a dog, how should this be confirmed?
Via microfilariae test (peripheral blood smear or Modified Knott's test)
137
How many injections of melarsomine are given in the recommended protocol?
3 (day 61, 90, 91)
138
Treatment with which antibiotic is recommended prior to initiation of melarsomine for canine HW?
Doxycycline
139
What is the most common primary cardiac tumor in dogs?
Hemangiosarcoma
140
What is the second most common primary cardiac tumor in dogs?
Aortic body tumors
141
What is the most common cardiac neoplasm (both primary/secondary) in cats?
Lymphoma
142
Where is the most common location for canine cardiac HSA?
Right auricle
143
Treatment options for cardiac HSA in dogs (2)
- Surgical resection
- Adjuvant chemo (doxo-based protocols)
144
What is the T-tubule?
Invaginations of the sarcolemma (muscle membrane) which are in close contact with the sarcoplasmic reticulum. They transmit action potentials into the interior of the cell. Present in skeletal and cardiac muscle.
145
Which of the following is/are decreased in pulmonary hypertension?
A) Endothelin
B) Prostacyclin
C) Nitric oxide
D) Angiotensin II
B & C: NO & prostacyclin
146
Which of the following can lead to hyperdynamic (waterhammer) pulses?
A) PDA
B) VSD
C) Tricuspid valve dysplasia
D) Pulmonic stenosis
E) Aortic insufficiency
(Select all that apply)
A & E
147
Which receptor is responsible for Ca++ release from the sarcoplasmic reticulum during muscle contraction?
Ryanodine receptor
148
Which of the following is caused by a L-R PDA?
A) R-sided volume overload
B) R-sided pressure overload
C) L-sided volume overload
D) L-sided pressure overload
C volume overload leading to eccentric hypertrophy of the left heart
149
A cat presents with a BP of 170mmHg and no signs of TOD. What is the best next step?
Recheck in 1mo
150
Deficiency in which amino acid is associated with DCM (nutritional phenotype) in cats
Taurine
151
Which channel closes in phase 3 of the action potential in ventricular cardiomyocytes?
Ca++
152
What is responsible for S1 heart sound?
Closure of AV valves
153
What is responsible for S3 heart sound?
Rapid ventricular filling
154
What is responsible for S4 heart sound?
Atrial systole/late ventricular filling (diastasis)
155
How does constrictive pericarditis manifest clinically?
R-sided CHF
156
A soft systolic murmur over the left heart base with splitting of S2 is associated with which congenital heart defect?
ASD
157
What type of murmur is expected with a small membranous VSD?
Holosystolic murmur over R side
158
What type of murmur is expected with concurrent SAS and aortic dysplasia?
"To and fro" murmur
159
What type of murmur is expected with mitral or tricuspid valve dysplasia?
Holosystolic murmur over affected valve
160
A systolic ejection murmur is heard over the left heart basis in a French Bulldog puppy. What is the most likely diagnosis?
Pulmonic stenosis
161
What type of murmur is expected in severe subaortic stenosis?
Holosystolic murmur over the left heart base
162
What is Poiseuille's law?
Laminar flow in a cylindrical tube is strongly related to radius of the tube (r^4)
163
A P wave which varies in morphology is characteristic of what condition?
Wandering pacemaker
164
An ECG shows normal HR but QRS complexes are wide and negative on leads I/II/III. What is this called?
Right BBB
165
Splitting of the S2 heart sound in combination with syncope and R-sided heart failure is seen with which condition?
Pulmonary hypertension
166
Name 2 antiarrhythmics used to treat both supraventricular and ventricular tachycardias
Procainamide (class IA)
Amiodarone (class III)
Sotalol (class III)
167
What is the treatment for constrictive pericarditis?
Pericardiectomy
168
How does dobutamine cause vasodilation?
B2 agonism
169
Name 2 effects of bradykinin
Vasodilation
Bronchoconstriction
170
Which nitrate vasodilator acts equally on arteries and veins?
Nitroprusside
171
Mechanism of action of glycoside plants (e.g., Foxglove, Oleander, Yew)
Similar to digoxin- Na/K ATPase inhibitor
