Cardiac Failure

Question 1

What aspects of a CV examination are especially important when assessing degree and cause of cardiac failure?

Answer 1

BP

Pulse (rate, rhythm; rapid AF may cause HF or be the result of HF)

JVP

Murmurs

Chest

Oedema

Question 2

What findings might be expected on examination in a patient with cardiac failure?

Answer 2

Crackles (creps) on auscultation

Elevated JVP (indicates high RA and therefore RV EDP; often correlates with high LA and LV EDP)

Oedema (alongside an elevated JVP causes other than cardiac failure are unlikely)

Question 3

What is cardiac failure termed when it is caused by the body’s increased needs?

Answer 3

High output heart failure

Question 4

What is the Frank-Starling law?

Answer 4

Stretch of the myocardium increases contractility (therefore SV increases with EDV)

Question 5

What are some of the possible mechanisms for pure RHF? Give examples of causes for each mechanism

Answer 5

Pulmonary HTN: cor pulmonale, PE

Structural disease: pulmonary or tricuspid valvular disease, R ventricular cardiomyopathy

Pericardial disease

Question 6

List 7 causes of cardiac failure

Answer 6

IHD

Valvular heart disease

Hypertensive heart disease

Congenital heart disease

Cardiomyopathy

Cor pulmonale

Pericardial disease

Question 7

What additional forms of treatment are available for cardiac failure? What is the goal of each?

Answer 7

Biventricular pacing (cardiac resynchronisation to improve function)

Implantable cardioverter defibrillator (to prevent SCD as a result of ventricular arrhythmias)

Cardiac assist devices and transplantation (uncommon)

Question 8

List 4 broad causes of SOB

Answer 8

Cardiac

Respiratory

Anaemia

Poor fitness

Question 9

What are 4 key parts to patient diagnosis in suspected HF?

Answer 9

Is it HF?

What is the underlying cause?

What is the precipitating cause of this episode?

What other problems are there?

Question 10

Hows does RAAS help to maintain CO in cardiac failure?

Answer 10

Na+ and H2O retention

K+ loss

Vasoconstriction

Question 11

What factors influence CO?

Answer 11

Preload

HR

Contractility

Afterload

Question 12

What are the main drug classes used to treat cardiac failure? Give an example of each

Answer 12

Aldosterone antagonists (spironolactone), ACEI (“pril”), ARB (“sartan”)

Beta blockers (“olol”)

Calcium channel blockers

Diuretics (frusemide)

Question 13

Give examples of possible complications of HF?

Answer 13

Cardiac ischaemia

Arrhythmias

Renal failure

Electrolyte imbalance

Liver failure

Question 14

What are the 4 main principles of cardiac failure treatment and what is the aim of each?

Answer 14

Reduce preload: relieve congestion and oedema (BUT be careful not to reduce CO too much)

Block RAAS: long term fluid loss, vasodilation

Block SNS: block direct cardiac toxic effect

Treat underlying and precipitating causes

Question 15

List 9 factors which may precipitate decompensated cardiac failure

Answer 15

A F****** BAD TIME:

New Arrhythmia (esp AF)

Fluid overload

Poor BP control

Anaemia

Change in Drugs

Thyrotoxicosis

Infection (esp pneumonia)

New MI or ischaemia

Pulmonary Embolus

Question 16

What are the 2 possible mechanisms underlying cardiac failure and what measurement differentiates the 2?

Answer 16

Systolic dysfunction (reduced ejection fraction)

Diastolic dysfunction (stiff diastolic function, normal ejection fraction; less common)

Question 17

Describe the progression from compensated to severe heart failure

Answer 17

In compensated cardiac failure, output may be maintained via fluid retention (however this may cause venous congestion)

In severe cardiac failure, CO is low and there is pulmonary and peripheral oedema

Question 18

What venous pressure is required to cause pulmonary or systemic venous congestion?

Answer 18

>20-30 mmHg

Question 19

What Ix are appropriate where cardiac failure is suspected? What are the expected findings?

Answer 19

CXR: ABCDE (alveolar oedema, Kerley B lines - intestitial oedema, cardiomegaly, dilated prominent upper lobe vessels, effusion - pleural)

Echocardiogram: chamber size (may be normal or increased), function (look for evidence of systolic or diastolic dysfunction), valves (look for valvular incompetence or stenosis), overall structure (look for evidence of hypertrophy)

Question 20

What aspects of the patient’s Hx are important to elicit when looking for the underlying cause of cardiac failure? Think of the 7 main causes!

Answer 20

IHD: previous MI

Valvular heart disease: PHx rheumatic fever, known murmur

Hypertensive heart disease: PHx of HTN and degree of control

Congenital heart disease: PHx of congenital heart defect

Cardiomyopathy: alcohol, cytotoxic drugs

Cor pulmonale: PHx lung disease (including asthma, COPD, cystic fibrosis, pulmonary fibrosis)

Pericardial disease: signs of RHF (may precede signs of LHF)

Question 21

Define cardiac failure

Answer 21

CO less than body needs (usually due to reduced CO but rarely due to increased body needs; “high output HF”)

Question 22

What is the physiological response to reduced contractility in cardiac failure?

Answer 22

Reduced CO = reduced renal blood flow, causing activation of RAAS and leading to fluid retention

Reduced CO also stimulates the sympathetic NS, causing increased NA release and an initial increase in contractility

Question 23

List 3 causes of diastolic dysfunction which may precipitate cardiac failure

Answer 23

Infarct-related scar

Chronic HTN

Ventricular hypertrophy

Question 24

How is LHF due to systolic dysfunction classified in terms of its severity?

Answer 24

Mild: 40-50% EF

Moderate: 30-40% EF

Severe: less than 30%

Question 25

What are the limitations of the physiological response to cardiac failure?

Answer 25

Fluid retention results in venous congestion

SNS stimulation increases contractility which results in arterial vasoconstriction (increasing afterload); SNS also has a direct toxic effect on the myocardium, and may cause ventricular arrythmias

Question 26

What are the 4 possible mechanisms underlying oedema? Give examples for each

Answer 26

Increased venous pressure (HF)

Decreased osmotic pressure (liver or renal failure)

Lymphoedema (cancer)

Increased capillary permeability (infection, inflammation)