Lecture 9 9/3/24 Flashcards
What are the characteristics of afterload reduction?
-vasodilators decrease peripheral vascular resistance
-results in an increase in stroke volume
-blood pressure is minimally affected
-easier for sick heart to push blood forward
Which drugs are used as vasodilators?
-ACE inhibitors such as enalapril, benazepril, and captopril
-amlodipine
What are the effects of ACE inhibition?
-vasodilation
-decreased aldosterone concentrations
-beneficial “neuroendocrine” effects
What are positive inotropes?
drugs that increase contractility of the heart
Which drugs are positive inotropes?
-digoxin
-dobutamine and other catecholamines
-pimobendan
What are the characteristics of pimobendan?
-calcium sensitizing “inodilator”
-phosphodiesterase inhibitor with favorable effects on myocardial energetics
What outcomes have been seen with pimobendan in clinical patients?
-decreased mortality in doberman pinschers with stage C DCM
-improved survival relative to ACE inhibition in dogs with stage C MR
What are the characteristics of heart rate in systolic failure therapy?
-control of the congestive state indirectly causes heart rate to decrease in most cases
-exception is animals with pathologic tachyarrhythmia
What are the characteristics of spironolactone?
-aldosterone antagonist that functions as a weak diuretic
-decreases mortality in people with CHF at a dose that does not affect hemodynamics
Why are the extra-renal effects of spironolactone important?
aldosterone antagonist characteristic helps with the supra-physiologic aldosterone conc. seen in heart failure patients; these conc. can contribute to myocardial fibrosis without treatment
What are the characteristics of spironolactone use in dogs?
-benefit is uncertain when used with standard treatment such as pimobendan
-use is reasonable when combined with drugs such as benazepril
What are the characteristics of treatment for patients with stage A heart failure?
-patients are predisposed to heart failure, but no clinical disease present
-no value to treatment
-important to screen these patients regularly
What are the characteristics of stage B2 mitral valve disease?
-grade 3/6 or louder murmur caused by MVD
-VHS > 10.5
-echo. evidence of left atrial and left ventricular enlargement
What is the indicated treatment for stage B2 mitral valve disease?
pimobendan
What is the main characteristic of stage B dilated cardiomyopathy?
echo. evidence of enlarged end-systolic ventricular dimension
What is the indicated treatment for stage B dilated cardiomyopathy?
pimobendan
What is the indicated treatment for stage C heart failure?
-furosemide
-ACE inhibitor
-pimobendan
-possibly spironolactone
What is the indicated treatment for stage D/advanced heart failure?
-optimized ACE inhibitor/pimobendan dose
-frequent renal function monitoring
-triple diuretic therapy with furosemide, spironolactone, and hydrochlorothiazide
-additional vasodilation
-hospitalization for parenteral therapy
What is cardiorenal syndrome?
term used to describe worsening renal function in patients with cardiac disease
What are the goals of therapy when treating acute/decompensated heart failure?
-decrease venous/filling pressure
-temporary oxygen supplementation
-improve cardiac performance
How is acute/decompensated heart failure diagnosed?
-thoracic radiographs
-possibly echo.
Why is it possible to use BNP measurements in diagnosing heart failure?
BNP conc. increase in association with increases in ventricular filling pressures
When is it appropriate to treat patients with empirical therapy for suspected heart failure?
when risks associated with restraint for diagnostic evaluation exceed the predicted benefit of having answers from the tests
What are the general measures taken when treating patients with acute/decompensated heart failure?
-supplemental O2
-cage rest
-narcotics or acepromazine to reduce anxiety
Why is fluid therapy not indicated in the majority of heart failure patients?
-preload is already maximal when CHF is present
-IV fluid administration increases venous pressures
Which drugs are indicated in treating acute/decompensated heart failure?
-IV furosemide
-oral pimobendan
Which monitoring tools/tests should be used when treating a patient with acute/decompensated heart failure?
-ECG
-physical exam
-HCT
-total protein
-BUN
-urine output
-body weight
