Week 4.5 Heart failure Flashcards
(98 cards)
1
Q
Heart failure is defined as?
A
The inability of the heart to maintain a cardiac output appropriate to systemic metabolic requirements.
2
Q
Heart failure may be a ____ output state.
A
Low
3
Q
Low output state is where?
A
Forward pump function of the heart is impaired and cannot meet normal metabolic needs.
4
Q
High output state is when?
A
When the pump function of the heart is normal but systemic metabolic needs are excessive.
5
Q
Examples of low output state?
A
Cardiomyopathy or myocardial infarction.
6
Q
Examples of high output state?
A
Thyrotoxicosis and beri-beri
7
Q
Thyrotoxicosis
A
Excess of production of thyroid hormone
8
Q
Beri-beri
A
Vitamin B1 deficiency or thiamine deficiency
9
Q
Wet beri-beri causes?
A
Heart failure
10
Q
Heart failure is usually a ____ condition, but in some circumstances may be acute.
A
Chronic
11
Q
Example of acute heart failure
A
Acute valvular regurgitation
12
Q
Chronic heart failure pathophysiology
A
Heart adapts and remodels in an attempt to compensate.
Remodelling includes ventricular dilatation and eccentric myocardial hypertrophy.
13
Q
Acute heart failure pathophysiology
A
Ventricular dilatation does not have time to develop and the major compensation is an increase in heart rate.
14
Q
Underlying cause in patient with heart failure?
A
This is the pathological process affecting the heart leading to impaired myocardial pump function
15
Q
A precipitating cause of heart failure is?
A
This is a factor or event which results in decompensation of the heart and symptoms.
16
Q
Typical precipitating causes of heart failure are?
A
Factors placing an additional load upon the heart such as fever, anaemia or systemic infection.
17
Q
Arrhythmias such as atrial fibrillation may precipitate??
A
May precipitate overt heart failure
18
Q
Coronary artery disease cause?
A
Impaired blood supply, with or without myocardial infarction -> heart failure
19
Q
Valve disease leads to?
A
Increased haemodynamic load on the heart e.g. aortic stenosis or aortic/mitral regurgitation
20
Q
Heart failure is often due to cardiomyopathy which is?
A
Dysfunction of the systolic contractile function of the myocardium, resulting in dilatation of the cardiac chambers.
21
Q
Causes of dilated cardiomyopathy?
A
- Alcohol abuse
- Previous myocarditis
- Hereditary defects in myocardial metabolism
- Metabolic abnormalities such as hyper/hypo-thyroidism
- Haemochromatosis
- Drugs or heavy metal poisoning
- Important drug cause is anti-cancer drug: adriamycin
22
Q
Less common cause of heart failure?
A
Restrictive cardiomyopathy
23
Q
Pathophysiology of restrictive cardiomyopathy
A
- Thickened and stiff ventricular myocardium due to fibrous infiltration or deposition of abnormal glycoproteins.
24
Q
Most common cause of restrictive cardiomyopathy in Australia
A
Amyloidosis
25
Amyloidosis manifest mostly in?
Older women
26
Clinical assessment is based upon the patient's symptoms:
Dyspnoea, orthopnoea, fatigue, exercise tolerance
27
Severity of clinical symptoms can be graded according to?
New York Heart Association from Class 1 (mild symptoms) to Class 4 (severe restriction of activity)
28
What does the NYHA Class physical examination include?
- Signs of heart failure
- Peripheral oedema
- Elevation of the jugular venous pressure
- Displacement of the apex beat of the heart
- Auscultatory signs such as atrial or ventricular gallop sounds and murmurs of aortic or mitral regurgitation
29
Describe functional capacity of NHYA Class 1
Patients with cardiac disease but resulting in no limitation of physical activity. Ordinary physical activity does not cause undue fatigue, palpitation, dyspnoea or anginal pain
30
Describe functional capacity of NHYA Class 2
Patients with cardiac disease resulting in slight limitation of physical activity. They are comfortable at rest. Ordinary physical activity results in fatigue, palpitation, dyspnoea or anginal pain.
31
Describe functional capacity of NHYA Class 3
Patients with cardiac disease resulting in marked limitation of physical activity. They are comfortable at rest. Less than ordinary activity causes fatigue, palpitation, dyspnoea or anginal pain.
32
Describe functional capacity of NHYA Class 4
Patients with cardiac disease resulting in inability to carry on any physical activity without discomfort. Symptoms of heart failure or the anginal syndrome
33
ECG may reveal?
Previous myocardial infarction or signs of left ventricular hypertrophy or document an arrhythmia (e.g. atrial fibrillation)
34
Chest X-ray provides an indication of?
Cardiac size, and is important for assessment of pulmonary congestion, with evidence of upper lobe venous distension or interstitial oedema.
35
Biochemical tests are directed towards?
Evaluating consequences of heart failure (i.e. blood electrolytes and creatinine) and also towards possible causative factors such as anaemia (FBC), alcohol abuse (liver function tests), endocrine abnormalities (thyroid function tests)
36
Normal adult left ventricular ejection fraction is?
50-70%
37
Ejection fraction is given by?
Stroke volume / end-diastolic volume
38
Cardiac imaging such as echocardiography or equilibrium radionuclide ventriculography provide information about?
Cardiac size and pump function, quantified by ejection fraction
39
In general, patients with an ejection fraction below _____ have severe heart failure.
25%
40
Is Heart failure a diagnosis?
No.
41
What is oedema?
Accumulation of fluid in the interstitial space. Occurs from imbalance of forces across the capillary wall.
42
What is the interstitial space
Extracellular space which is outside the capillaries and between the cells
43
To distinguish oedema from other cause of tissue swelling, what is the test needed?
Classic test is the oedema 'pit', i.e. firm pressure with a finge leaves a dent which takes a minute or so to obliterate.
44
List other causes of tissue swelling
Fat, tumours, chronic inflammation and fibrosis.
45
Distribution of oedema is often diagnostic and can involve which areas?
- ankles
- Legs
- Sacrum
- Scrotum
- Peritoneum
- Pleural cavities,
- Lung tissue (pulmonary oedema is particularly serious)
- Face
- Lips
- Glottis
- Vocal cords (may cause asphyxiation in severe food allergies)
- Brain
46
Starling discovered?
Starling's Law of the Heart and the first hormone, secretin.
47
One factor that favours movement of fluid out of the capillary is?
Hydrostatic pressure within the capillary.
48
Hydrostatic pressure within the capillary is offset by ?
Hydrostatic pressure of the interstitial space itself (often close to zero)
49
Mean pressure in capillaries is around?
25 mmHg
50
Mean pressure in capillaries at the arterial end is _____ and _____ at the venous end.
Higher; lower
51
Because molecules with very large molecular weights do not easily move through the capillary wall, these are retained in the capillary and exert a?
Colloid osmotic pressure which tends to attract fluid into the capillary.
52
Plasma proteins (chiefly albumin) exerts a colloid osmotic pressure of ____ which does?
20 mm Hg which attracts fluid into the capillary
53
How is the rate at which fluid crosses the capillary wall determined?
Sum of these four pressures multiplied by the capillary permeability.
54
Final step of excess fluid clearance?
Excess fluid in the interstitial space is removed by the lymphatics
55
Hydrostatic pressure in the capillary (and all other blood compartments) is increased when?
Sodium and water are retained, as in heart failure and steroid overdose, which can cause massive oedema over the ankles, legs and sacrum.
56
An important distinction is that left sided heart failure tends to cause _____ whereas right-sided heart failure tends to cause _______.
Pulmonary oedema; generalised oedema
57
Reduced serum albumin is another large category causing?
Generalised oedema
58
Reduced serum albumin can be caused by?
Malnutrition (kwashiorkor) or malabsorption of proteins, loss of proteins as in renal failure or nephrotic syndrome or failure to synthesise albumin, which occurs in liver disease.
59
Increased capillary permeability occurs in many allergic reactions and is probably caused by?
Histamine release e.g. bee stings, food allergies and these can cause dangerous but short lived oedemas.
60
Blockage of lymphatic channels by infection (filariasis leading to elephantiasis) or by tumour, surgery or radiation damage can also result in?
Oedema
61
In patients with poorly controlled or uncontrolled heart failure, dental treatment is best ?
Delayed until they are more medically stable.
62
In emergency dental situations, a conservative approach is recommended for an unctonrolled patient prescribing?
Antibiotics and analgesics
63
Patients with left sided heart failure causing pulmonary oedema and worsening dyspnoea, when undergoing dental treatment, it should be done so?
Partially reclined position, or sitting upright.
64
Oxygen may need to be administered during treatment of severely affected patients while reduced cardio-respiratory function makes ?
General anaesthesia contraindicated
65
Intravascular injection of local anaesthetics containing _____ should be avoided, so ensure good anaesthetic technique with an aspirating syringe.
Adrenalin
66
Avoid using large doses of local anaesthetic containing adrenalin in patients using _____.
Beta-blockers
67
_____ is cardiotoxic and should be avoided.
Bupivicaine
68
______ containing adrenalin also should not be used.
gingival retraction
69
Aortic or mitral valve damage may indicate the need for ________.
Antibiotic prophylaxis.
70
Alternatively, patients with right-sided heart failure due to pulmonary disease may require _____ during treatment.
Oxygen.
71
How to monitor patients with cystic fibrosis?
Use ECG and oximetry
72
Side effects of drugs used in cardiac failure?
Patients who have hypertension and or ischaemic heart disease complicated by heart failure may be using a number of drugs with the potential to cause both oral side effects:
- lichenoid reaction
- dry mouth
- burning tongue
- Loss of taste
- Paraesthesia
- Gingival hyperplasia
73
Coughing is a side effect in some patients taking ______ may impact negatively upon a dental procedure.
ACE inhibitors
74
Patients taking a digitalis glycoside (digoxin) should be given ______ or ______ cautiously as the combination can potentially precipitate _______.
adrenaline or nor-adrenaline; arrythmias
75
A maximum of _____ adrenaline (two cartridges of 2% lignocaine with 1:100 000 adrenaline) is recommended for these patients.
0.036 mg
76
Serum levels of digoxin can be increased by concomitant administration of ?
- Tetracycline
- Erythromycin
- Gentamicin
- Possibly other antibiotics
77
NSAIDs such as _____ may also interact with digoxin, so are best avoided.
Diclofenac
78
_____ is a common side effect of digoxin.
Vomiting
79
Syncope (or fainting) is triggered by an?
Abrupt decrease in arterial blood pressure , which in turn results from a variety of causes.
80
Most common cause (___________) is associated with changes in sympathetic and cardiac vagal activity.
Vasovagal syndrome
81
Syncope is defined as?
Disturbance or loss of consciousness as a result of an abrupt reduction of blood flow to the brain, which is typically short duration (seconds to minutes)
82
Describe the pathophysiology of causes of syncope
Normally blood flow to the brain is regulated by an intrinsic autoregulatory mechanism which maintains blood flow at a level sufficient to meet the metabolic demands of the brain, even if there are transient decreases in mean arterial pressure. However, if there is a large fall in mean arterial pressure (i.e. to a level < 45-50 mmHg), the autoregulatory mechanism is insufficient to maintain a level of cerebral blood flow that is sufficient to meet the metabolic demands of the brain, resulting in a loss of consciousness. Arterial blood pressure is normally regulated by the baroreceptor reflex, so that a large decrease in blood pressure (hypotension) can only occur if the factor causing the hypotension is so great that it cannot be compensated for by the baroreceptor reflex, or if the baroreceptor reflex itself is impaired.
83
What happens when you obstruct outflow from left or right ventricles or impairing pumping capacity of the ventricles?
Fall in cardiac output, which if severe enough, will lead to a large fall in arterial pressure.
84
Factors that lead to obstruction to circulation?
Aortic stenosis (which narrows the aorta), hypertrophic cardiomyopathy (in which the contractility of thec ardiac muscle is impaired), pulmonary stenosis (which narrows the pulmonary artery), or pulmonary embolism (in which outflow resistance of the right ventricle is greatly increased)
85
List four main factors that cause abrupt and large decreases in blood pressure, leading to syncope:
- Obstruction to the circulation
- Transient arrhythmias
- Neurological disorders
- Vasovagal syndrome
86
Transient arrhythmias pathophysiology?
A rapid increase in rate of ventricular contractions (Ventricular tachycardia) may result in a very short filling time and hence greatly reduce stroke volume, leading to a reduced cardiac output despite the increased heart rate.
87
Ventricular tachycardia may occur as a result of abnormalities of?
Cardiac pacemaker (sino-atrial node) or in conduction of action potentials through the heart.
88
Other abnormalities of the pacemaker or cardiac conduction pathways may lead to a slowing of the heart (bradycardia) , which if severe enough will also lead to?
Greatly reduced cardiac output.
89
Decrease in cardiac output in turn will result in a decrease in?
Arterial blood pressure
90
Neurological disorders can result in dysfunction of the vagal parasympathetic nerves innervating the heart, or sympathetic vasoconstrictor nerves innervating the blood vessels leading to?
Impairment of the normal baroreceptor reflex control of blood pressure. A feature of these conditions is a reduction in blood pressure when the subjects stand up (postural hypotension)
91
Most common cause of syncope is characterised by?
Combination of vagally mediated cardiac slowing (bradycardia) and peripheral vasodilation.
This results in both cardiac output and total peripheral resistance is reduced, so that arterial pressure falls sharply, to the point where transient cerebral ischaemia and loss of consciousness occurs.
92
Most important factor of vasovagal syndrome
Vasodilation, because blockade of the vagally-mediated bradycardia (by injection of atropine) does not prevent the syncope.
93
Syncope attacks are usually initiated by?
Emotional stimuli (e.g. fainting at the sight of blood, or on receiving very bad news).
94
Vasovagal syncope occurs infrequently in healthy tissue, but in some people without obvious stimuli, what term is used?
Malignant vasovagal syndrome
95
Studies in humans have demonstrated that the vasodilation associated with vasovagal syncope is due to an?
Inhibition (usually complete abolition) of sympathetic vasoconstrictor nerve activity.
96
Inhibition of sympathetic vasoconstrictor nerve activity indicates?
Baroreceptor reflex is suppressed during a vasovagal attack, because the fall in arterial pressure would normally trigger a reflex increase in sympathetic vasoconstrictor activity.
97
What is the stereotyped autonomic response, triggered by centres in the forebrain that receives inputs activated by emotional stimuli?
Sympathoinhibition and cardiac vagal activation.
98
Survival value of the vasovagal is?
Unclear, but conceivable. It is the human equivalent of "playing dead" reaction displayed by some animals when confronted by a predator.
