Internal Medicine Flashcards
What is ACS?
Acute Coronary Syndrome, a spectrum of clinical presentations including Stable Angina, Unstable Angina, NSTEMI, STEMI and Sudden Cardiac Death
What is the primary cause of ACS?
Atherosclerosis - most cases occur from the disruption of a previously non-severe lesion.
What is angina?
The result of myocardial ischaemia caused by an imbalance between myocardial O2 supply and demand resulting from a narrowing or spasm of the coronary arteries.
Describe the pathophysiology of angina.
Decreased blood supply –> decreased O2 –> switch from aerobic to anaerobic respiration –> ischaemia -> ATP degraded to adenosine. Adenosine diffuses to extracellular space causing arteriolar dilation and anginal pain.
What are the types of angina?
Stable angina
Prinzmetal’s Angina
Angina Decubitus
Unstable Angina
What are the hallmarks of stable angina?
It is brought on by exertion and relieved by rest.
What is Prinzmetal’s angina?
Angina symptoms commonly occurring at rest caused by vasospasm of the coronary arteries. Can be associated with ST elevation.
What is angina decubitus?
A variant of angina that occurs at night when the patient is recumbant.
What is Unstable angina?
ACS in the absence of biochemical evidence of myocardial damage. Characterised by:
- Prolonged >20 mins
- Not relieved by GTN
- Onset at rest
- Angina post recent MI
What are the precipitants of Angina?
Exercise, mental and emotional stress, sexual activity, tachycardia, increased metabolic demands (fever, thyrotoxicosis, hypoglycaemia).
What are some causes of angina?
Coronary atherosclerosis
Coronary artery spasm
Coronary syndrome X (Microvascular angina - angina in the presence of normal coronary arteries)
Systemic collagen vascular disease: Scleroderma, SLE
Inflammatory vascular diseases: Kawasaki, Polyarteritis nodosa, Takayasu arteritis
Describe the symptoms of Angina
Chest pain, discomfort, radiating to the neck, jaw, arms, back. Pain is often preceded by exertion or stress. Typically relieved by rest or GTN. May be SOB, Levine sign - Placing fist on centre of chest.
What are the clinical features of angina?
Tachycardia. ECG: may be normal, but may show ST segment depression or inverted T waves.
What investigations should be done for Angina?
ECG
Troponin, Lipids, HbA1c, Hb
Stress test, coronary angiogram
How to diagnose Angina?
Clinically, ECG and trop to rule out AMI
How to treat angina?
Risk factor modification
Statins, BP management, Antiplatelet and anticoagulation, nitrates
revascularisation.
Define AMI
Irreversible myocardial cell death secondary to prolonged ischaemia
In an AMI, what vessels are normally occluded?
LAD 40-50%, RCA 30-40%, LCx 15-20%.
Describe the pathophysiology of AMI and how the resulting acute heart failure, cardiogenic shock, and arrhythmias occur.
AMI: Disruption of cholesterol-laden plaque, exposure of pro-thrombotic substances that promote rapid platelet aggregation, thrombin generation and thrombus formation causing an interruption to blood flow. Or embolus.
HF: If significant amount of myocardium is damaged, LV pump functions is depressed: CO, SV and BP are reduced and systolic volume is increased. Results in acute HF and cardiogenic shock.
Arrhythmia: Ischaemia disrupts the normal biochemistry and depolarisation of the cell. VF and VT can occur.
Define NSTEMI
Myocardial infarction that does not show diagnostic ECG changes but does have a troponin rise
What can be found on ECG for NSTEMI?
ST depression, T wave inversion, arrhythmias and other non-diagnostic ischaemic changes.
What is the pathophysiology for an NSTEMI?
It’s a subendocardial infarct. Iner 1/3 of myocardium is permanently damaged, not transmural. The inner 1/3 is subject to higher pressure and the last part to receive perfusion, so often the first part that is damaged.
What are the characteristic ECG changes for a STEMI?
ST elevation over 1mm in chest leads, over 2 in limb leads in at least 2 contiguous leads.
Reciprocal depression
Arrhythmias
(It’s a transmural infarct)
What are ten risk factors for AMI?
HTN
DM
Dyslipidaemia
Obesity
Chronic renal insufficiency
Smoking
Male
Female post-menopause
Age
Metabolic syndrome
CAD
FHx AMI under 50
Cocaine use
What doest ST depression in leads V1-V4 suggest?
A posterior STEMI
When does a troponin rise, and how long does it stay up?
Elevated within 4-6 hours of injury, remains elevated for around 10 days.
What is the treatment for AMI?
O2 with sats under 94%
Aspirin
GTN
Analgesia: Morphine, fentanyl
Antiemetics: Ondansetron
Heparin
Clopidogrel / Ticagrelor
B-blockers decrease myocardial workload
Symptomatic management
PCI is gold standard within 90 mins. If over 120 mins, consider fibrinolysis.
When should a PCI be done?
Within 90 mins for STEMI. 12-24 hours for NSTEMI.
What is PCI?
Where catheter inserted in femoral or radial artery to assess coronary arteries. Dye is injected to visualize patency of coronary arteries and area of occlusion is visualized. The clot is removed, the area ballooned and stented.
What medications should be started following an MI?
DAPT
B blocker
ACEI
Statin
GTN
Aldosterone Antagonist (EF <40%) - do ECHO.
What are the complications of AMI?
Death
Arrhythmia
Rupture (ventricular, septal, papillary)
Tamponade
Heart failure
Valve disease
Aneurysm of ventricle
Dressler’s syndrome
Embolism
Recurrence / mitral regurgitation.
What is Beck’s triad of acute cardiac tamponade?
3 Ds: Distant heart sounds, Decreased arterial BP, Distended neck veins.
What is Dressler’s Syndrome?
Post MI syndrome. Develops 2-10 weeks after MI or heart surgery. Results in recurrent fever, chest pain, pericarditis. Possibly due to formation of autoantibodies against cardiac muscle post trauma.
What is cardiac failure?
When the heart due to an abnormality in cardiac function , fails to pump blood at a rate sufficient to meet the bodies metabolic demands or is only able to do so with an elevated diastolic filling pressure.
What are the types of cardiac failure?
Right heart failure
Left heart failure
Biventricular failure
HFpEF
HFrEF
Acute decompensated HF
Chronic compensated HF
How is heart failure classified?
Class I - No limitation of physical activity
Class II - Slight limitation of physical activity
Class III - Marked limitation of physical activity
Class IV - Sx occur at rest and discomfort with any physical activity.
What are the types of diuretics?
Thiazide diuretics, Loop diuretics, Potassium sparing diuretics
What are the types of anti-hypertensives?
ACE-I/ARB
B-blockers
a-blockers
CCBs
Describe the physiology of the RAAS.
Decreased perfusion to JGC in macular densa leads to increased renin secretion
Renin converts angiotensinogen (from the liver) to angiotensin I
Angiotensin I converted to Angiotensin II in lungs by ACE.
Angiotensin II:
- Increased aldosterone secretion from adrenal cortex: increased Na and water reabsorption and K excretion
- Increased ADH secretion from the posterior pituitary which increases H2O reabsorption in the CD
- Increased tubular reabsorption of Na, Cl, H2O and excretion of K
- Arteriolar vasoconstriction
- Increased sympatethic activity.
Give two examples of ACEIs and their dosages
Ramipril - 2.5-10mg/qd
Perindopril 5-10mg/qd
How do ACEIs work?
Reduce the synthesis of Angiotensin II by inhibiting the action of ACE. Results in: Vasodilation, decreased Na and water reabsorption, decreased Aldosterone and ADH secretion, net decrease in BP.
Constriction of efferent glomerular arteriole, decreased myocardial workload, increased renin secretion.
What are ACEIs indicated for?
HTN, HF, Renal failure, oedema.
What are the side effects of ACEIs?
Hypotension, angiotensin induced cough, angioedema (bradykinins are also dependent on ACE for their breakdown, may occur after years), hyperkalaemia (decreased aldosterone: responsible for K secretion.
What is the normal BUN?
1.5-10.7 mmol/L
What is BUN?
Blood urea nitrogen is a measure of the amount of urea in the blood. It is produced by the liver as apart of protein catabolism and primarily renally excreted. It is a marker of renal function but is affected by others.
What is the normal creatinine?
62-106 umol/L
What is creatinine and what is it used for?
It is formed by skeletal muscle and excreted in relatively constant amounts by the kidney. It is not reabsorbed by the kidney so estimates GFR. It is a good measure of renal function. Levels will become abnormal when over 50% of the nephron units have been damaged.
What is the normal Urea:Creatinine ratio?
40-100:1
What does a Urea:Creatinine ratio of 40-100:1 indicate?
Normal or post renal AKI
What does a urea:creatinine ratio over 100:1 indicate?
A pre-renal cause - urea absorption increased compared to creatinine
What does a urea:creatinine ratio under 40:1 indicate?
Intrinsic renal damage (urea unable to be absorbed, ecomes more similar to creatinine and the ratio gets closer to 1).
What are causes of increased U:C Ratio?
Drivers can use GPS
Dehydration
Corticosteroids
GI haemorrhage
Protein rich diet
Severe catabolic state
What are causes of decreased U:C ratio?
I am a Simple SR:
Severe liver dysfunction
Intrinsic renal damage
Malnutrition
Pregnancy
Low protein diet
SIADH
Rhabdomyolysis
What is the definition of polyuria?
Over 3L/day production
What is the definition of oliguria?
Less than 0.5 ml/kg/hr
What is the definition of anuria?
Less than 50ml / day
What is the level for microalbuminuria?
30-300 mg/L
How much protein is required for nephrotic syndrome?
Over 3 g per day
What is azotaemia?
Increase of BUN
What is uraemia?
Azotaemia associated with clinical signs, Sx and biochemical abnormalities
What is nephritic syndrome?
A clinical entity caused by glomerular disease with acute onset:
Haematuria with dysmorphic RBCs, renal casts
Decreased GFR
Proteinuria
HTN
What is nephrotic syndrome?
Also due to glomerular disease, characterised by marked proteinuria:
Hypoalbuminaemia
Oedema
Hyperlipidaemia
Lipiduria
What are the different types of UTI?
Lower UTI: Infection of the bladder and the lower urinary tract
Cystitis: Infection of the bladder
Pyelonephritis: Infection of the parenchyma and collecting system of the kidney.
What is the most common pathophysiology of UTIs?
Colonisation of the vagina followed by ascension into the urinary tract
What are the risk factors for UTIs?
Age (F - infants, preschool, sex, old; M- Infants and old)
Female gender (due to urethral length)
Hx of recurrent UTI
Spermicide
Pregnancy
Congenital abnormalities eg vesico-urethral reflux
Urinary tract obstruction, eg renal calculi
Residual urine in bladder eg neurogenic bladder, BPH
Instrumentation of bladder eg IDC
State 7 possible symptoms of a UTI
Dysuria
Frequency
Urgency
Difficulty urinating
Dark urine
Strong odour
haematuria
sensation of bladder fullness
suprapubic tenderness
Fever
Confusion and sepsis
What are 3 common organisms for UTIs?
E. coli
Staphylococcus saprophyticus (in YA female)
Enterobacteriacea and pseudomonas (second in hospital)
What are you likely to see on a UA for someone with a UTI?
Cloudy
Haematuria +
Leucocytes +++
Proteinuria +
Nitrites
Alkaline
How would you treat a UTI?
ABx should cover GM- (ecoli): Trimethoprim
What is acute pyelonephritis?
Infection of the renal tissue, calyces and renal pelvis.
What symptoms would distinguish acute pyelonephritis from UTI?
Flank / back pain / costovertebral angle
Fever, chills, rigors
N+V
Confusion
What investigations would you do for suspected acute pyelonephritis?
UA, Urine MCS,
Renal US
2nd line, CT (not standard)
How much blood needs to be present in 1 L urine for macroscopic haematuria to be visible?
Approx 1 mL
What is the diagnostic limit for microscopic haematuria?
over or equal to 3 RBCs/HPF.
State 8 causes of haematuria
Menstruation contamination
Trauma
Infection
Stones
Malignancy
Coagulation abnormalities
Nephrotoxic medications
Instrumentiaon
Exercise induced haematuria
How would you treat acute pyelonephritis?
Trimethoprim / augmentin
Surgical drainage
Fluids