Deck VII Flashcards Preview

USMLE World Missed Questions > Deck VII > Flashcards

Flashcards in Deck VII Deck (30):

What characterizes trochlear nerve palsy?

Vertical diplopia.


In fragile X syndrome, increased number of trinucleotide repeats leads to gene inactivation of the FMR1 gene via what mechanism?

Hypermethylation of cytosine bases.


Thiamine is a cofactor for which enzymes involved in glucose metabolism?

Pyruvate dehydrogenase, a-ketoglutarate dehydrogenase, transketolase.


An increase in what product after thiamine infusion is diagnostic for thiamine deficiency?

Erythrocyte transketolase levels.


Activity of what product can be measured to diagnose thiamine deficiency?

Erythrocyte transketolase levels.


What is a major cause of suicide that access to is considered a major risk factor for completed suicide?

Access to firearms.


What symptoms are characteristic of opioid withdrawal?

Abdominal pain, nausea, vomiting, diarrhea, piloerection, lacrimation, diaphoresis.


When are MAO-Is indicated for treatment of depression?

Atypical depression.


What symptoms characterize atypical depression?

Mood reactivity, leaden fatigue, rejection sensitivity, increased sleep, increased appetite.


In the condition 'nursemaid's' elbow, what structures are damaged?

Radial head subluxation, causing weakness/ paralysis of forearm extensor compartment muscles and wrist drop.


What is the mechanism of action of ethosuxamide?

Blocks T type Ca2+ channels that trigger/ sustain rhythmic bursts in thalamic neurons; ethosuxamide decreases calcium current in thalamic neurons.


In blunt aortic trauma, where is injury to the aorta most common?

Aortic isthmus which is tethered to the ligamentum arterosum (i.e. at top of descending segment)


Describe the murmur heard in a patient with aortic regurgitation.

Murmur best heard on the left sternal border when the patient sits up and leans forward at end expiration; early diastolic, high pitched and blowing decrescendo murmur (severe AR can be holodiastolic and present with absence of the A2 heart sound)


What vessels serve as the venous drainage of the heart?

Coronary sinus.


Which tissue extracts the most oxygen from blood?

The heart


In a patient with tetralogy of fallot, squatting during an episode of severe cyanosis and dyspnea (tet spell) helps to:

Increase systemic vascular resistance (increased SVR compared to pul. Vascular resistance permits a greater fraction of total cardiac output to pass through the lungs, thus improving arterial oxygenation.


A patient on physical exam with a cardiac murmur, bounding femoral pulses, and carotid pulsations accompanied by head bobbing indicates what condition:

Aortic regurgitation.


Name three precipitating factors for isolated episodes of atrial fibrillation.

Binge alcohol consumption, increased cardiac sympathetic tone, pericarditis.


What EKG findings are characteristic of a-fib?

Irregularly irregular QRS complexes and absent P waves. P waves are always absent in a-fib because coordinated atrial contractions do not occur.


The cardiac action potential is associated with increased and decreased membrane permeability to which ions respectively?

Increased permeability: Na, Ca; Decreased permeability: K


A chronic AV shunt causes what types of changes to cardiac output, total peripheral resistance, and venous return?

Increases cardac output (increased sympathetic stimulation); decreased TPR; increased venous return.


Elevated activity of which enzyme predisposes a patient with atherosclerotic lesions to plaque rupture and myocardial infarction?

Metalloproteinases (degrade collagen of the plaque's fibrous cap)


Pulmonary Capillary Wedge Pressure (PCWP) most accurately measures what pressure?

Left atrium end diastolic pressure


Name two drugs that are selective vasodilators of coronary arteries.

Adenosine, dipyridamole.


What is the mechanism of action of adenosine and dipyridamole on coronary arteries?

Vasodilation of coronary arterioles in NON ischemic regions, thus diverting blood flow from ischemic regions. This is called 'coronary steal'.


What is pulsus paradoxus?

A decrease in systolic blood pressure of greater than 10mmHg with inspiration


Name four conditions that may cause pulsus paradoxus.

Acute cardiac tamponade, constrictive pericarditis, severe obstructive lung disease, restrictive cardiomyopathy.


On auscultation, what is the best indicator of severity of mitral stenosis?

Length of time between S2 (specifically the A2 component caused by aortic valve closure) and the opening snap. Shorter interval indicates more severe stenosis.


What compensation mechanism is used to initially attenuate clinically apparent edema in patients with right heart failure?

Increased tissue lymphatic drainage.


What characteristic defect is associated with a wide, fixed splitting of S2 that does not vary with respiration?

Atrial septal defect (creates left to right shunt)