Coronary Flashcards
Regulation of coronary circulation
Intrinsic and extrinsic mechanisms
Intrinsic regulation
Depends on the metabolic deman of myocardium
Metabolic auto regulation (h co2) causes vasodilation
Myogenic response
Ability of coronary arteries to respond to changes in BP
Endothelial regulation
NO and endothelin
Extrinsic regulation
Neural and hormonal
Sympathetic. By beta receptors cause vasodilation
Parasympathetic decreases heart rate
maintaining baseline coronary vasomotor tone.
Epinephrine vasodilation
Angiotensin II and norepinephrine are vasoconstrictors
Differential diagnosis of chest pain
1psychological emotional stress
2 Myocarditis and Pericarditis: Usually retrosternal to the left of sternum (or Lt/Rt shoulder).
Precipitated with movement and respiration
Sharp
3 Mitral valve prolapse: sharp left-sided chest pain
4 Aortic dissection: This pain is severe ,sharp,
Oesopageal pain: This can mimic anginal pain
Bronchospasm : patients with asthma may describe exertional chest tightness
Musculoskeletal chest pain
Stable angina It may occur whenever there is imbalance
•between myocardial oxygen supply and demand.
Resting ECG
The ECG may show evidence of previous MI
Managment of angina
Determine the extent and severity of the arterial disease
Identify the risk factors and control them
Control symptoms
Antiplatelet therapy
Low-dose(75mg) aspirin
Clopidogrel (75mg)
Nitrates
Cause vasodilation
Increases oxygen supply and decrease ox demand
Sublingual GTN
BB
lower myocardial oxygen demand
Calcium channel antagonists
Decrease heart demand by decreasing herat contractility and BP
Dihydropyridine reflex tachycardia.
• Non-dihydropyridine brady cardia
Side-effects:
Can precipitate heart failure, peripheral edema, headache, flushing.
Nicorandil
Has the dual properties of a nitrate & ATP sensitive K+ channel agonist, so has arterial and venous dilating properties.
Ivabradine:
It induces bradycardia by modulating ion channels (funny channel) in the sinus node (when BB cannot be used).
Ranolazine:
Sodium channel blocker
• In acute MI, —————is almost always present at the site of rupture or erosion of an atheromatous plaque.
Occlusive thrombus
Sometimes unrecognized (silent MI)
in elderly or diabetic patient.
Impaired myocardial function
Hypotension
Increased jvp
Cold peripheries
Oliguria
Third heart sound
Repeated ECG
The diagnosis is uncertain or persistent
Echocardiography
Cardiac rupture
Mural thrombus
Ventricular function
