PBL Medicine- Purnuske Flashcards
Describe physical exam findings associated with septic emboli
Petechial rash Septic emboli (PE, stroke) Roth’s spots Splinter Hemorrhages under the fingernails
What is the mechanism of action ceftriaxone?
Binds penicillin binding proteins (transpeptidase) and inhibits peptidoglycan synthesis Gram + and - organisms Bactericidal Less susceptible to penicillinases
MOA of penicillin G?
IV/IM form Binds to pbp (transpeptidase) preventing it from cross-linking peptidoglycan Gram + sensitive to B-lactamases
Define penetrance
the percentage of individuals with given genotype who exhibit the phenotype associated
What are symptoms of endocarditis?
FROM JANE Fever Roth Spots Osler’s Nodes Murmur Janeway Lesions Anemia Nailbed hemmorhages Emboli (septic)
Chest Pain Heart failure Abnormal heart rhythms “flu-like” illness
Myocarditis
What bugs causes Myocarditis?
Coxsachievirus B Adenovirus
Chest Pain Tachycardia 3-COMPONENT FRICTION RUB EKG Changes
Pericarditis
What bugs cause pericarditis?
COX A and B Echovirus Influenza
Rank the most common organisms that cause endocarditis?
Staph aureus Strep Viridans Enterococus Species Strep pyogenes
Which pathogen is associated with IV drug use?
Staph
What do pathogenicity islands usually contain?
Methicillin resistance
Where does strep viridans normally reside? Is it normal flora?
Yes, in the oral cavity
What bug is a common cause of endocarditis after GI or OB procedure?
Enterococcus Species
Describe the pathophysiology and relationship between bacterial endocarditis and heart murmurs?
Colonization of mitral valve –> mitral valve regurgitation –> turbulent flow –> murmur
What are the disadvantages of using TEE to visualize heart valves?
Swallowed probe More expensive Higher risk
Describe the relationship between endocarditis and stroke
- Vegetation (clumps of bacteria + mesh of fibrin) can break off the valve and travel to other parts of the body, blocking flow
- Risk of embolization is the highest during the first week of therapy, and in patients with mobile vegetations or >10 mm in diameter occurin on the mitral valve
- Endocarditis can also lead to hemorrhaging in the brain and other parts of the body via septic erosion of arterial walls
- Overalll, stroke risk in patients with endocarditis is 9.1% in the 12 months after diagnosis
What is the mechanism for tPA? Risks? Benefits? Contraindications?
Converts plasminogen to plasmin which degrades fibrin clots
Benefits = increase functional independence without affecting mortality at 3-6 months if given with in 3 hours
Risks= intracranial hemorrhage within the first 7 days after administration
Contraindications = suspected/confirmed endocarditis, intracranial hemmorhage, neuro surgery, head trauma, stroke in past 3 months, uncontrolled hypertension
What is the difference between stable and unstable angina?
Stable angina = chest pain that arises with exertion or emotional stress
Unstable = chest pain that occurs at rest
What is prinzmetal angina?
episodic chest pain unrelated to exerction
Due to coronary artery vasospasm
What are the clinical features of an MI
Severe, crushing chest pain, lasting >20mins that radiates to the left arm or jaw
Diaphoresis
Dyspnea
Symptoms are NOT relieved by nitro
What causes a myocardial infarction?
Usually due to rupture of an atherosclerotic plaque with thrombosis and COMPLETE OCCLUSION of a coronary artery –> result in necrosis of myocardium and cell death
What is the most common artery involved in MI?
LAD - causes infarction of the anterior wall and anterior interventricular septum
Toponin I
most sensitive and specific marker for MI
Rise 2-4 hours, peak 24, return by 7-10 days
What is lab marker is good for looking at re-infarction?
Creatine Kinase MB
Goes up and down quickly
WWhat is the acronym for motivational interviewing?
O-open ended questions
A- affirmation
R- reflective listening
S- summarize
What are two complications of therapies for MIs?
Reperfusion injury- free radical further damages myocytes
Calcium inlux that leads to hypercontraction of myofibrils = contraction band necrosis
What are the microscopic changes seen in MI?
1 Day- coagulative necrosis
1 week- Inflammation (neutrophils and MACs)
1 month- healing (granulation tissue, fibrosis)
LDL receptor genetics? for hypercholesteremia
Autosomal Dominant
CHanges in LDL receptor gene
Treatment for an MI?
Aspirin and/or heparin/eptifibatide: limits thrombosis
Morphine: pain
Supplemental O2: minimize ichemia
Nitrates: vasodilates
B-blocker: slows heart, decreases O2 demand and risk for arrhythmia
ACE inhibitor: decreases LV dilation
Fibrinolysis or angioplasty- open blocked vessel
Describe Heart sounds
S1 (lub)- closure of the tricuspid and mitral valves
S2 (dub)- closure of the pulmonary and aortic valves
S3- normal in children, ventricular dilation (systolic ventricular failure)
S4- low ventricular compliance
Define locus heterogeneity
Is a single disorder, trait, or pattern of traits causes by mutations in multiple genes at different chromosomal loci
Describe the pathogenesis of atherosclerosis
- Damage to the intima
- Lipid deposits in the intima
- Lipids become oxidized in intima
- Macrophage and neutrophils become filled with fat in intima
- This is called a foam cell/ fatty streaks
- Then there is smooth muscle migration, proliferation, and extracellular matrix deposition
- This forms a fiberous plaque
NOTE* Necrotic Lipid core, covered by a fibromusclar cap!
Modifiable risk factors for atherosclerosis
Hypertension
Hyperlipidemia
Diabetes
Smoking
Non-modifiable risk factors for atherosclerosis
Age
Genetics
Gender
What is a thoracic aneurysm and what is it usually caused by?
balloon like dilation of the thoracic aorta
Due to weakness in the aortic wall usually caused by tertiary syphilis
- tertiary sphilis = endarditis = inflammation of small arteries (including vaso vasorum)
- Decreased blood flow to the media and adventia
- Weakening of wall
What are common compliations of a thoracic aneurysm?
Dilations of the aortic valve root (leads to aortic valve insufficiency)
Compression of mediastinal structures as it balloons
Thrombosis or emobli (disruption of laminar blood flow)
Abdominal Aortic Aneurysm is usually caused by…
Atherosclerosis
Usually below renal artiers, and above bifurcation
Thickening of wall - decreased O2 perfusion - atrophy of media and adventia - weakening of blood vessel wall
Describe the pathophysiology of acute aortic dissection
= intimal tear with dissection of blood through media of the aortic wall
Usually occurs in proximal 10 cm of the aorta
Need two things
- stress (like the proximal 10 cms)
- Pre-existing weakness of the media (usually caused by HTN)
- HTN causes arteriolosclerosis of vaso vasorum
- Decreaed perfusion to media
- Media atrophy/weakening
Results of acute aortic dissection? Symptoms?
Descending- will compress the renal arteries
Ascending- cardiac tamponde - sudden death
Symptoms:
Sharp, tearing chest pain, that radiates to the lower back
Raynauds phenomenon? And what are the color changes due to?
Type of peripheral artery disease characterized by decreased blood flow to skin due to arteriolar vasospasm in response to cold temps or emtional stress.
White = vasoconstriction & ischemia
Blue = tissue hypoxia and cyanosis
Red= rewarming and reperfusion
Candidate Gene approach
Case control approach
Looking for statistcal association between specific gene variant and disease of interest
Linkage Analysis
Family-based approach
Look for pre-specified gene markers in highly variable in DNA regions.
Those found more common in diseased members are said to be linked to the causative gene.
Then pursued with fine mapping
Genome Wide Association Studies
SNPs are genotyped across the entire genome in subjects with and without the disease.
SNPs that differ in frequency between cases in comparison with controls are “associated” with disease
Define Syncope
Transient loss of consciousness secondary to cerebral hypoperfusion characterized by rapid onset, short duration, and complete spontaneous recovery
What are the three classifications of syncope?
Neurally mediated
Cardiogenic
Autonomic dysfunction
Describe neurally mediated (reflex) syncope
Vasovagal- need precipitating event
Situational- happens after coughing, sneezing, peeing, pooping, exercising, etc.
Carotid sinus syncope- shaving, massage, others
Describe cardiogenic syncope
hypoperfusion to the brain due to an arrhythmia, structural disease,
Describe syncope due to autonomic dysfunction
Can be primary autonomic failure: lewy body disease, parkinson
OR
Secondary: Diabetic or amyloid neuropathy, spinal cord injury
(Includes orthostatic hypotension)
How long do you have to be arrhythmia-free before driving according to the american heart association?
6 months
