pathopharm wk 7 and 8

P wave

atrial depolarization

ORS complex

ventricular depolarization

T wave

ventricular repolarization

PR interval

shows AV node delay

QT interval

reflects total ventricular activity

ST changes or prolonged intervals

suggest ischemia or instability

CO

HR x SV

factors affecting stroke volume

• preload

• afterload

• contractility

preload

how much the heart is filling before diastole

adequate optimizes contraction via Starling method

• increased in hypervolemia

• regurgitation of cardiac valves

• heart failure 

afterload

resistance that must be overcome to eject the blood out

primarily affected by arterial tone and systemic vascular resistance

• determined by BP and arterial resistance

• is increased in hypertension and vasoconstriction

Frank-Starling principle

states that the heart pumps more blood per beat (stroke volume) when the ventricles are stretched more and preload is increased

• the heard will adapt based on venous return

Laplace’s law

• helps explain why high pressure hearts are less efficient

  • larger ventricles require more oxygen to generate pressure

  • hypertrophy thickens walls to reduce stress temporarily

  • chronic pressure overload increases oxygen demand

inotropic effect

change in force and velocity of myocardial contraction

chronotropic effect

affects rate of heart rate 

dromotropic effect

affects speed of electrical impulse conduction through the heart

BP

CO x SVR (systemic vascular resistance)

nitric oxide

hormonal factor that causes vasodilation

endothelin

hormone factor that causes vasoconstriction

drug targets for cardiovascular pharm.

volume, resistance, and rate/contractility

diuretic drugs

thiazides for hypotension

loop diuretics for heart failure or edema

diuretics: monitoring

• monitor I’s and O’s

• weights

• K+ 

• BP

ACE inhibitor drugs

• end in -pril

ACE inhibitors: monitoring

• dry cough

• hyperkalemia (K+ levels)

• renal function

Angiotensin II Receptor Blockers (ARBs)

• end in -sartan

ARBs: monitoring

• leads to vasodilation

• avoid pregnancy or bilateral renal stenosis

• monitor BP, renal labs, and K+

Calcium Channel Blockers (CCBs)

• -pine

• verapamil

• diltiazem

  • DHP or non-DHP

CCBs: monitoring

• avoid w grapefruit juice 

• cautiously combine w beta blockers

• watch for hypotension, edema, and bradycardia

Beta-blockers

• end in -olol

beta-blockers: monitoring

• hold if HR < 60 or SBP < 90

• nonselective (1st gen) - blocks beta 1 and beta 2 (heart and lungs)

  • do NOT give to pt with COPD or asthma

• selective (2nd gen) - blocks beta 1 (heart)

• can mask hypoglycemia in diabetics

vasodilators

• hydralazine - for chronic HF or hypertension

• nitroprusside - for crisis

nitrates

nitroglycerine

isosorbide dinitrate

isosorbide mononitrate 

nitrates: monitoring

• never combine with ED drugs (PDE5 inhibitors like sildenafil)

• headaches are expected w nitrates

positive inotropes

cardiac glycosides - digoxin

beta agonists - dobutamine

phosphodiesterase inhibitors (milrinone)

positive inotropes: monitoring

digoxin - check K+, renal function, and digoxin level (0.5-2.0 ng.dL) and hold if HR < 60bpm

all - monitor continuous ECG and BP, stop when stable, assess apical pulse for 1 min

what to give a pt in atrial fibrillation

beta blockers

• ex: Metoprolol, Atenolol, Bisoprolol, Carvedilol

CCBs

• ex: diltiazem and verapamil

amiodarone

sotalol

class 1 antiarrhythmic drugs

sodium blockers - lidocaine

class 2 antiarrhythmic drugs

beta blockers - metoprolol

class 3 antiarrhythmic drugs

potassium blockers - amiodarone and sotalol

class 4 antiarrhythmic drugs

calcium blockers - diltiazem and verapamil