Cardiomyopathy & Atherosclerosis - PDF

MEHLMANMEDICAL.COM HY Cardiomyopathy points for USMLE - Can be isolated ventricular or diffuse 4-chamber dilation. Causes are multifarious, but a key feature is systolic dysfunction, where ejection fraction is reduc...

MEHLMANMEDICAL.COM HY Cardiomyopathy points for USMLE - Can be isolated ventricular or diffuse 4-chamber dilation. Causes are multifarious, but a key feature is systolic dysfunction, where ejection fraction is reduced (i.e., 30mm. - Septal myectomy is done if the left ventricular outflow tract pressure gradient is >50mm Hg. But it should be noted ICD is usually first-line. - Heart failure due to diastolic dysfunction, where HTN is not the cause. - JVD is HY for RCM. An S4 can also be seen. The heart will not be dilated. - HY causes are Hx of radiation (leads to fibrosis), amyloidosis, and hemochromatosis. - Student might say, “I thought you said hemochromatosis was DCM. So if we have to choose on the exam, which one is it?” The answer is, whichever the vignette gives you. If they say a large cardiac silhouette Restrictive (RCM) with an S3 and lateralized apex beat, that’s DCM. If they say JVD + S4 + nothing about a lateralized apex beat, you know it’s RCM. - Amyloidosis is protein depositing where it shouldn’t be depositing. Highest yield cause of amyloidosis on USMLE is multiple myeloma, which will lead to RCM. - Since RCM is diastolic dysfunction, the arrows are the same as HCM, which are: « EF; « LVEDV; ­ LVEDP. Atherosclerosis basic points for IM - Most acceleratory risk factors are diabetes mellitus (I and II), followed by smoking, followed by HTN, in that order. - HTN is most common risk factor, but DM and smoking are worse. I talk a lot about this stuff in my HY Risk Factors PDF if you want extensive detail. - HTN is most acceleratory specifically for carotid stenosis (systolic impulse pounds carotids à endothelial damage). - Stroke, TIA, or retinal artery occlusion in patient with high BP is due to carotid plaque launching off to the brain/eye. If patient has normal BP, think AF instead, with left atrial mural thrombus launching off. - Patient over 50 with Hx of cardiovascular risk factors who now has accelerated HTN, think renal artery stenosis (narrowing due to atherosclerosis). - Plaques can calcify. The more calcium there is in a plaque, the more mature it is often considered to be. Calcium scoring is routinely done in patients who have coronary artery disease in the assessment of plaque progression. MEHLMANMEDICAL.COM 26  MEHLMANMEDICAL.COM - Statins have 2 HY MOAs on USMLE: 1) inhibit HMG-CoA reductase; 2) upregulate LDL receptors on hepatocytes. - Ezetimibe blocks cholesterol absorption in the small bowel. - Bile acid sequestrants (e.g., cholestyramine) result in the liver pulling more cholesterol out of the blood. - Fibrates upregulate PPAR-a and lipoprotein lipase; best drugs to decrease triglycerides. HY Angina points for IM - Chest pain that occurs predictably with exercise. - Due to atherosclerotic plaques causing >70% occlusion; can be calcific. - Classically causes ST depressions on ECG. - Nitrates (e.g., sublingual isosorbide dinitrate) used as Tx à nitrates “donate” nitric oxide (NO) that upregulates guanylyl cyclase within venous smooth muscle à increased cGMP à relaxation of venous smooth muscle à increased Stable angina venous pooling of blood à decreased venous return à decreased myocardial oxygen demand à mitigation of chest pain. - Nitrates are contraindicated with PDE-5 inhibitors (e.g., Viagra) due to risk of low blood pressure. - Sodium nitroprusside used for hypertensive emergencies dilates arterioles in addition to the veins. If USMLE asks you where this drug acts, choose arterioles. - Chest pain that is unpredictable and can occur at rest. - Due to partial rupture of atherosclerotic plaque leading to partial occlusion. Unstable angina - ST depressions on ECG. - Diltiazem is answer on new 2CK NBME for patient with unstable angina. - Patients need cardiac catheterization. - Vasospastic angina that occurs at rest (i.e., watching TV or while sleeping) in younger adults; it is not caused by atherosclerosis. - ST elevations are seen on ECG. - You must know that Prinzmetal is also known as variant angina pectoris. There Prinzmetal angina is an NBME Q that gives vignette of Prinzmetal, but answer is “variant angina (variant angina pectoris) pectoris.” - Treatment is nitrates (can cause coronary artery dilation unrelated to the venous pooling effects) or dihydropyridine calcium channel blockers (e.g., nifedipine). Avoid a1-agonists in these patients (cause vasoconstriction), as well as non-selective b-blockers like propranolol (can cause unopposed a effects). Hypertensive Emergency + urgency - HTN >180/120 + signs of end-organ damage. - The latter can be hypertensive encephalopathy (confusion), nephropathy (poor renal function tests), retinopathy, acute heart failure, etc. Emergency - BP should be ¯ by no more than 20-25% in the first hour, as drastic ¯ can compromise perfusion to the brain and vital organs. - Blood pressure should be brought under 160/100 by 24-48 hours. - Drugs used are IV sodium nitroprusside, IV nicardipine, IV labetalol, and oral captopril. - HTN >180/120 + no signs of end-organ damage. Urgency - Blood pressure should be brought under 160/100 by 24-48 hours. - Drugs used are IV sodium nitroprusside, IV nicardipine, IV labetalol, and oral captopril. MEHLMANMEDICAL.COM 27  MEHLMANMEDICAL.COM Shock types Systemic vascular Pulmonary capillary wedge pressure Cardiac output (CO) resistance (SVR) (PCWP) Cardiogenic ¯ ­ ­ Hypovolemic ¯ ­ ¯ Septic ­ (early) / ¯ (late) ¯ ¯ Anaphylactic ­ (early) / ¯ (late) ¯ ¯ Neurogenic ¯ ¯ ¯ Obstructive ¯ ­ ¯ - Septic, anaphylactic, and neurogenic are all under the envelope of distributive shock. - ­ PCWP for cardiogenic is one of the highest yield path points on USMLE. - For deeper explanations, go to my HY Arrows PDF. HY Endocarditis points - Bacterial infection of valve in patient with no previous heart valve problem. - Caused by Staph aureus on USMLE. - Left-sided valves (i.e., aortic and mitral) most commonly affected because of greater pressure changes (i.e., from high to low) within left heart, resulting in Acute endocarditis turbulence that enables seeding. - IV drug users à venous blood inoculated with S. aureus à travels to heart and causes vegetation of tricuspid valve. - Staph aureus is coagulase positive. - Bacterial infection of valve in patient with history of valve abnormality (i.e., congenital bicuspid aortic valve, Hx of rheumatic heart disease). - Caused by Strep viridans on USMLE. You need to know S. viridans is can be Subacute endocarditis further broken down into: S. sanguinis, S. mutans, and S. mitis. - Hx of dental procedure is HY precipitating event, where inoculation of blood occurs via oral cavity à previously abnormal valve gets seeded. - New-onset murmur + fever = endocarditis till proven otherwise on USMLE. - Reactive thrombocytosis (i.e., high platelets) can occur due to infection. This is not unique to endocarditis, but it is to my observation USMLE likes endocarditis as a notable etiology for it. In other words, if you get an endocarditis question and you’re like, “Why the fuck are platelets 900,000?” (NR 150-450,000), don’t be confused. Random points - Hematuria can occur from vegetations that launch off to the kidney. - Endocarditis + stroke-like episode (i.e., focal neurologic signs) = septic embolus, where a vegetation has launched off to the brain. - Janeway lesions, Osler nodes, splinter hemorrhages, etc., are low-yield for USMLE and mainly just school of medicine talking points. - HACEK organisms nonexistent on USMLE. - Blood cultures before antibiotics is important for 2CK. - Transesophageal echocardiography (TEE) confirms diagnosis after blood cultures. Transthoracic echocardiography (TTE) is not done for endocarditis. - For 2CK, empiric treatment for endocarditis is vancomycin, PLUS either gentamicin or ampicillin/sulbactam. - Vancomycin targets gram-positives (including MRSA). Gentamicin targets gram- negatives. Management - Endocarditis prophylaxis given prior to a dental procedure is usually ampicillin or a second-generation cephalosporin, such as cefoxitin. - Indications for endocarditis prophylaxis are: 1) Hx of endocarditis (obvious); 2) If there is any prosthetic material in the heart whatsoever; 3) If there is any congenital cyanotic heart disease that has not been completely repaired (if it’s been completely repaired with prosthetics, give prophylaxis); MEHLMANMEDICAL.COM 28  MEHLMANMEDICAL.COM 4) Hx of heart transplant with valvular regurgitation of any kind. - Highest yield point for USMLE about endocarditis prophylaxis is that mitral valve prolapse (MVP) and valve regurgitations or stenoses are not an indication. In other words, do not give prophylaxis if the patient has MVP, MR, AS, etc. In addition, bicuspid aortic valve is not an indication. Rheumatic heart disease (rheumatic fever) HY points - Strep pyogenes (Group A Strep) oropharyngeal infection results in production of antibodies against S. pyogenes’ M-protein that cross-react with the mitral valve (i.e., molecular mimicry; type II hypersensitivity). - Can occur with the aortic valve in theory, but on USMLE, it is always mitral valve. - Results in mitral regurgitation acutely and mitral stenosis late, as discussed earlier. - Presents as JONES (J©NES) à Joints (polyarthritis), © Carditis, subcutaneous Nodules, Erythema marginatum (annular, serpent-like rash), Sydenham chorea (autoimmune basal ganglia dysfunction that results in dance-like movements of the limbs). - Cutaneous Group A Strep infections don’t cause rheumatic fever, but can still cause PSGN. - Treatment is penicillin. Conditions confused for cardiac path - NBME loves trying to make you think this is an MI. - They’ll give you young, healthy patient who feels doom / like he or she is going to die. - Sometimes they mention in stem Hx of MI in family as distraction. Panic attack - They can say patient has mid-systolic click, as discussed earlier, and then they ask for cause of patient’s symptoms à answer = panic disorder, not MVP. Student gets confused, but MVP is almost always asymptomatic, where panic attack is clearly cause of the patient effusively hyperventilating. - Treat with benzo. - Orthostatic hypotension is defined as intravascular fluid depletion causing a drop of systolic BP >20 mmHg and diastolic BP >10 mmHg when going from supine to standing. Orthostasis - Shows up on 2CK IM form as exactly a drop of 20 and 10, respectively, for systolic and diastolic BPs in a patient with fainting à answer = “intravascular fluid depletion.” - Diuretic use is big risk factor. - Fainting in response to stressor (e.g., emotional trigger). - Stress triggers an initial sympathetic response, which in turn triggers a compensatory parasympathetic response. This latter response is excessive in Vasovagal syncope some people, where the peripheral arterioles dilate and the heart slows too much à decreased cerebral perfusion à lightheadedness/fainting. - 2CK wants you to know a tilt-table test can be used to diagnose, where a reproduction of symptoms can occur. - USMLE likes this for both Steps 1 and 2. - They’ll say dude was shaving then got lightheadedness or fainted. Carotid sinus Mechanism is ­ stretch of carotid sinus baroreceptors à ­ afferent CN IX hypersensitivity firing to solitary nucleus of the medulla à ­ efferent CN X parasympathetic firing down to cardiac nodal tissue à ¯ HR à ¯ CO à ¯ cerebral perfusion. - Inflammation of cartilage at rib joints. - Will present as chest pain that worsens with palpation or when patient Costochondritis reaches over the head or behind the back. These two findings are clear indicators we have an MSK condition, not cardiac. - Can be idiopathic, caused by strain (e.g., at the gym), or even post-viral. MEHLMANMEDICAL.COM 29  MEHLMANMEDICAL.COM - MSK condition asked twice on 2CK material that has nothing to do with the lungs, despite the name. - This is viral infection (Coxsackie B) causing sharp lateral chest pain due to Pleurodynia intercostal muscle spasm. Sometimes students choose pericarditis, etc., even though the presentations are completely disparate. - Creatine kinase can be elevated in stem due to ­ tone of muscle. - Viral infection causing inflammation of the pleura (layers covering the lungs), leading to sharp chest pain. Viral pleurisy - If this is the answer, CK will be normal (unlike pleurodynia, because it’s not MSK). - Can cause angina-like pain in patient without cardiovascular disease. Diffuse esophageal spasm - I discuss this in detail in the Gastro section. - Can present as chest pain confused for MI. ECG will be normal, clearly. Gastroesophageal reflux - I discuss GERD in detail in the Gastro section. Arterial vs venous disease - Caused by atherosclerotic disease; presents as diminished peripheral pulses in patient over 50 who has risk factors, e.g., diabetes, smoking, HTN. - Lower legs can be shiny and glabrous (trophic changes). - Arterial ulcers are small and punched-out; located on tops/bottoms of feet and toes. Arterial disease - Ankle-brachial indices (ABIs) are first step in diagnosis (exceedingly HY on 2CK), which compare BP in ankle to the arm; if