March 20 - Cardiology Flashcards
Blunt aortic injury
Most common cause is MVA - sudden deceleration.
Injury most commonly occurs to aortic isthmus which is lethered by the ligamentum arteriosum, making it realtively fixed and immobile. Located between aortic arch and descending aorta
Most ant and post chambers of heart
RV most anterior and is most likely damaged by blunt trauma. LA is most posterior and can compress the esophagus or recurrent laryngeal nerve resulting in dysphasia and hoarseness
Coronary circulation
Aorta gives rise to R coronary and L main coronary.
R coronary supplies right side of heart and in 90% gives off PDA which supplies the inferior wall and inferior septum
L main coronary gives rise to LAD and L circumflex. LAD supplies anterior wall, ant septum, and apex. LCX supplies lateral wall. In 10%, PDA comes off of LCX
Mitral valve prolapse pathophys
Caused by stretching of chordae teninae and billowing of valves. Can lead to tear and sudden HF in a young woman
Locations of SA, AV nodes and bundle of his
SA node: right atrial wall
AV node: intra-atrial septum
Bundle of his: intra-ventricular septum
Paradoxical embolism: pathophys
Stroke from venous thromboembolism. Most common causes are ASD and PFO.
In ASD there is an open defect in the atrial wall due to absence of septum primum or secundum during development. Characteristic S2 split
PFO caused by fusion between primum and secundum not occuring after birth. Usually stays functionally closed because LA pressure exceeds RA pressure, but can get transient increases in RA pressure that produce transient R to L shunt and allow for paradoxical embolism to form
Beta1 receptors
Found in cardiac tissue and renal JG cells
Beta blocker selectivity
B1 selective: atenolol, esmolol, betaxolol, metoprolol (A through M)
B1 and B2: nadolol, pindolol, propranolol, timolol (N through Z)
Alpha and beta: carvedilol and labetaolol
S gallolyticus
Nonenterococcal group D strep. Causes subacute endocarditis. Associated with colon cancer in 25% of cases
Barorecptor physiology
Two baroreceptors
1) carotid sinus: uses glossopharyngeal to communicated with brain
2) aortic arch: uses vagus nerve to communicate
Increase BP results in increased stretch on baroreceptors and increased firing to brain. Brian responds via sympathetic and parasymathetic systems to alter HR and constrict and dilate vessels. Fast response (compared with slower venous response)
Venous pressure tracing
A wave: RA contraction (rise in pressure)
C wave: tricuspid valve closure
X descent: atrial relaxation
V wave: venous filling, opening of tricuspid valve
Y descent: emptying of atrium
Changes in venous pressure tracing: large a wave, canon a wave, absent a wave, giant v wave
Large a wave: tricuspid stenosis; atria have to contract harder
Canon a wave: AV dissociation, such as complete heart block; atria contract against closed tricuspid resulting in really high pressure
Absent a wave: afib, just see v wave after v wave
Giant v wave: tricuspid regurg
Liver angiosarcoma
CD31+ (PECAM1)
Associated with aresenic and PVC exposure
Nitroglycerin
Venodilator that acts by decreasing preload and decreasing cardiac demand. Large veins are most susceptible
At large doses, can also affect arterioles, causing flushing and headache
Mitral stenosis murmur
Opening snap caused by abrupt tensing of valve leaflets after S2. Timing correlates with severity of stenosis: increased severity results in increase LA pressure and valve opens more forcefully, decreasing A2 to opening snap interval.
Diastolic rumble intensity does not correlate well with stenosis severity
Lateral shift of PMI
Indicates an enlarged heart
Carcinoid heart disease
Fibrous deposits on tricuspid and pulmonic valves resulting in stenosis and regurg. Lungs inactivate serotonin so left side unaffected
Changes in murmurs with inspiration
Increases venous return to right side increasing intensity of R murmurs
Decreases venous return to left side, decreasing intensity of L murmurs
Maneuvers that alter preload and effect on murmurs
Increase preload: leg raise, squatting
Decrease preload: valsalva (increases intrathoracic pressure and compresses veins), standing (blood falls toward feet, away from heart)
Most murmurs increase when preload increased with exception of hypertrophic cardiomyopathy and mitral valve prolapse
Maneuvers that alter afterload and effect on murmurs
Increase afterload: hand grip
Decrease afterload: amyl nitrate
Increased afterload increases backward flow murmurs, decreases forward flow murmurs
Drug effects: additive, synergistic, and permissive
Additive: combined effect of two drugs equal to sum of their individual effects
Synergistic: each drug has an effect individually but when used together, effect is greater than their sum
Permissive: drug not effective alone but increases efect of a second drug, allowing it to have max effect
Cardiac cath placement
Ideally in common femoral artery below the inguinal ligament as placement above the ligament can cause retroperitoneal hemorrhage
Class III antiarrhythmic: names
amiodarone, sotalol, dafetilide
Adenosine
Activates K+ channels, increasing K+ conductance and causing membrane potential to stay negative longer, decrasing sinus rate and increasing AV node conduction delay. Used to diagnose supraventricular tachyarrhythmias
Non-bacterial thrombotic endocarditis
Bland thrombus without inflammation or valve damage. Related to hypercoagulability, often from malignancy
Trousseau syndrome
Migratory thrombophlebitis due to hypercoag of malignancy, Vessel inflammation due to clot appears as nodule under the skin