What drug prevents clinical deterioration of pt's with left ventricular systolic dysfunction - heart failure AND improve symptoms.

Digoxin

When is digoxin indicated in HF?

Always with severe HF and added to regimen of patients with mild to moderate failure.

Digoxin is a first-line drug for treating HF.

True or False

False, it's a second-line drug.  Diuretics is the first-line drug.

Besides HF, what else does digoxin treat?

Arrhythmias

What conditions produce CHF?

Conditions that inc preload, inc afterload, or reduce myocardial contractility.

What happens when the heart fails?

Mean AP and CO decrease and circulatory failure ensues.

What does unterated CHF result in?

1.  Inc HR and dec contractility

places greater demand on the heart

 2.  Inc venous tone

results in edema

3.  Inc arteriolear tone (afterload)

Inc work for the heart

What is the primary inotropic drug used for CHF?

Digitalis (Digoxin)

What are the therapeutic strategies for treating CHF?

1.  Inotropics - inc contractility - heart

2.  Diuretics - dec fluid volume - kidney

3.  Vasodilators/ACE - dec pre/afterload - blood vessels

What is the MOA of digitalis?

Inhibits Na+, K+ movement across the myocardium cell membrane

Results in an increase in Ca++ influx which potentiates contractility of cardiac muscle

What is the physiologic response to Digoxin?

1.  ANS - inc vagal inflence-->inc HR, dec AV conduction, inc AV node refractory period, reduction of sympathetic tone and sympathetic vasoconstriction (this is why digoxin works for A-Fib

2.  Endocrine System - reduced production or release of renin, angiotensin & aldosterone

3.  Urinary System - inc renal blood flow, GFR, UO, Na excretion.

What is the clinical response to digoxin?

1.  Inc SV

2.  Dec end diastolic volume and pressure

3.  Dec heart size, venous and capillary pressure

4.  Dec in reflex sympathetic activity

5.  Dec systemic arterial and venous tone

6. dec fluuid volume and edema

What are the primary differences between digoxin and digitoxin?

1/2 Life - Digoxin shorter / Digitoxin longer

Onset - Digoxin rapid / Digitoxin

Excretion - Digoxin urine / Digitoxin liver 

Absorption - digoxin 60-100% / digitoxin 90-100% 

what is the most common cause of death when taking digoxin?

V Fib

What factors predispose a pt to dig toxicity?

1.  Hypokalemia - may be secondary to diuresis

2.  Concurrent use of drugs: quinidine, K+ depleting diuretics, corticosteroids and a variety of other drugs

3.  Disease States - hypothyroid, hypoxia, renal failure, myocarditis

What are the common adverse effects of digoxin?

1.  GI - anorexia, n/v - earliest signs!

2.  Cardiac - arrhythmias include AV Block and various tachyarrhythmia's. 

3.  Neurological - headache, fatigue, malaise, disorientation, confusion, visual disturbances

SEVERE digoxin toxicity can lead to SEIZURES!

How do you treat digoxin toxicity?

1.  DC digoxin and K+ wasting diuretics

2.  Administer K+ (monitor EKG)

3.  Antiarrhythmic agents

4.   Atropine - sinus brady

5.  FAB antibody fragments?

what should you monitor to assess response and prevent toxicity?

1.  EKG, Dig Level, Electrolytes, BUN, creatinine.

What are the most common drugs that cause an increase in dig levels?

1.  Quinidine

2.  Anuidaribe

3.  Flecaubude

4.  Propafenone

5.  Spironolactone

6. Verapamil 

7.  Erythromycin

8.  Tetracycline

9.  Dilantin

What drugs decrease intestinal absorption?

1.  Antacids

2.  Kaolin

3.  Cholestyramine

4.  Suculfrate

How do diuretics enhance the occurrence of digoxin toxicity?

Decrease renal clearance and by causing electrolyte changes including hypoK, hypoMag and HyperCa (thiazides).

What herb acts like cardiac glycosides and have similar effects to digoxin?

Hawthorn if the main one,

also St. John's Wort (lowers level)

What is a therapeutic range of digoxin?

0.5 - 2 ng/ml

What is the toxic levels of digoxin and digitoxin?

Digoxin - >2.5 ng/ml

Digitoxin - >35ng/ml