Cardiac failure

Epidemiology

It is about a disease attends, concerning nearly 2% of the American population with a mortality being able to reach nearly 30%, one year after its diagnosis. The economic costs of its assumption of responsibility in are very important (a little less than 30 billion dollars annual for the United States).

Physiopathology

The two large responsible mechanisms are a deterioration of the contraction of the cardiac muscle (systolic dysfonction, the ventricular Systole corresponding to time when the muscle, contracting, ejects blood towards the Aorte for the left ventricle, towards the pulmonary Artère for the ventricle right) and/or a deterioration of the diastolic function only (cardiac failure with preserved systolic function). These two mechanisms involve a reduction in the cardiac Débit.

Seldom, there exist cardiac failures with high flow. In fact, they are named thus because the permanent rise in the flow is the cause (and not the consequence) of the heart failure whose muscle is tired to assume such a flow.

Consequences of the reduction in the cardiac flow

The Sang brings nutrients and Oxygène to the whole of the organization. It also makes it possible to evacuate the " of them; déchets" to which belonged the Carbonic gas. A reduction in the blood flow thus does not make it possible to take up a correct duty of the organization.

In the event of moderate fall of the cardiac flow, the organization tends to adapt by preserving to the maximum the blood flow towards the vital bodies (brain, heart). It decreases for that intended for the other bodies by the means of a reduction in the gauge of the small arteries (vasoconstriction) by contraction of the muscular cells included in their wall. This redistribution of the flow has several serious consequences, in particular renal. The fall of the perfusion of the Rein S involves, in answer, an activation of the system Rénine - Angiotensine - Aldostérone which causes, on the one hand a retention of water and electrolytes with reduction in the volume of the urine (diuresis), which results in an increase in blood volume circulating (preload), and thus of the work of the heart; in addition a vasoconstriction with rise in the blood pressure (post-load), thus increasing the work of the heart. The increase in the work of the heart, by rise in the preload and/or the post-load is at the origin of a vicious circle; the natural evolution of cardiac failure is thus done towards a progressive and irremediable aggravation.

In the heart, the incapacity to correctly eject blood towards the downstream results in a stagnation of blood in the ventricle: the minimal pressure (known as telediastolic) is increased and passes from a few mm of mercury to more than 15 mmHg. This increase in the pressures is reflected upstream: on the left, towards the left auricle, pulmonary veins, pulmonary capillaries and the pulmonary artery, then even upstream, ventricle right, right auricle and venous system. The measurement of this rise in the telediastolic pressure, the veins (central venous Pressure) to the left ventricle, at the time of a cardiac catheterization or more often of a cardiac echography, allows the diagnosis of cardiac failure when the other elements do not make it possible to slice.

Attack of the systolic function

The cardiac Débit depends on the contractility (corresponding to the function " pompe" heart), post-load (corresponding overall to resistance to the ventricular ejection) or of the preload (corresponding to the filling of the ventricles by blood resulting from the upstream). Any deterioration of the one of these parameters can result in a table of cardiac failure.

Contractility

The cardiac flow is proportional to the heart rate and the systolic Volume of ejection. This last corresponds to the difference between diastolic volume (ventricle full) and the stroke volume (volume of the ventricle once emptied by the contraction of its muscle). The report/ratio systolic Volume of ejection / diastolic volume corresponds to the Fraction of ejection, given key to analyze the systolic function. It is higher than 60% at the individual normal and decreased in the event of anomaly of the contractility, being able to go down up to 20% in the event of major dysfonction.

When the fraction of ejection is decreased, the organization can maintain the flow in two manners: by increasing the heart rate, which explains the Tachycardie, and by maintaining a volume of systolic ejection constant by increasing diastolic volume.

The increase in diastolic volume has as a visible consequence an increase in the size of the heart. It in addition involves a stretching of the cardiac muscle fibers, which, because of its elastic properties, makes it possible to improve transitorily its contraction (mechanism of Franck-Starling ).

When these compensation mechanisms are exceeded, the cardiac flow decreases and becomes insufficient for the needs for the organization. A table of cardiac failure settles.

The contractility can be reached in the dilated cardiomyopathies, the Myocardite S, the ischemic cardiopathies, and in a general way in almost all cardiac pathologies at a very advanced stage.

Preload

The preload characterizes the conditions of filling of the ventricles.

The pressures of filling are high at the time of an untreated cardiac failure. This increase can be only not very visible but can also appear by a pulmonary edema by extravasation of liquids through the pulmonary capillary towards the cells. It can be also visible at the venous level (dilation of the veins of the neck, called jugular turgescence ). This preload is quantified by the measurement of the pressure at the end of the diastole (telediastolic) of the blood circuit. It can be made by the introduction of a catheter into a large vein (central Pression venous whose measurement is hardly any more done), into the right cardiac cavities, the pulmonary Artère to the pulmonary capillaries (by right catheterization with probe of Swan-Ganz ), into the left ventricle (by catheterization by retrograde way during a Coronarographie), or indirectly by cardiac echography-Doppler.

The post-load

The post-load corresponds to the force which the Myocarde must overcome to eject the Sang and it can be appreciated indirectly by resistance to the ejection of the left ventricle (the blood Pressure is an approximate appreciation of the post-load). When it increases in an important and prolonged way, that can involve a cardiac failure. It is typically increased during the arterial Hypertension, of the contracting of the aortic valve like during certain cardiomyopathy (cardiomyopathy obstructive).

Attack of the diastolic function

The cardiac diastolic function can be reached when there is an anomaly of the relieving , compliance .

The relieving of the cardiac muscle, corresponding to the relaxation of this last after its contraction, leads normally to the protodiastolic pressure decrease (at the beginning of Diastole) intraventriculaire below the pressure of the left auricle, thus creating a true phenomenon of ventricular aspiration (fast ventricular filling protodiastolic).

The compliance can be comparable with the relation between the existing pressure in the ventricle and the volume of Sang that this ventricle contains. It is in connection with the elastic properties of the muscle which can be disturbed.

The deterioration of relieving and compliance will involve a reduction in the filling of the left ventricle by loss of the post-systolic aspiration (after the Systole). Moreover, because of the " rigidité" cardiac, there is increase in the diastolic pressure and blood damning up (and this more especially as the cardiac rhythm of the subject will be fast).

Influence cardiac rhythm

The cardiac flow is, under the normal conditions, proportional to the heart rate. If the latter is in a chronic way, too low (Bradycardie), by auriculo-ventricular Bloc for example, a table of cardiac failure can settle.

If, on the contrary, the rate/rhythm is too fast (Tachycardie), the heart does not have time to fill correctly between each contraction: the filling is thus faded with fall of the flow consequently.

At the time of a auricular Fibrillation, the rate/rhythm of the auricle is extremely fast and disordered and the auricle loses any effective contractile activity then. The filling of the ventricles in is thus deteriorated and a table of cardiac failure can settle or be raised.

Compensation mechanisms

When a state of cardiac failure settles, the organization will implement a series of mechanisms (cardiac or extra-cardiac) to try to compensate for the failure of the cardiac muscle.

At the cardiac level, acceleration of the heart rate (Tachycardia), dilation of the left ventricle to maintain a Volume of systolic ejection sufficient, left ventricular Hypertrophy to decrease the parietal tension.

At the peripheral level (extra-cardiac), there is activation:

of the system adrenergic (effect tachycardisant and Inotrope, peripheral Vasoconstriction, stimulation of the System renin-angiotensin-aldosterone),
of the system System renin-angiotensin-aldosterone (vasoconstriction by the means of the angiotensin II, retention hydrosodée by the means of the Aldosterone),
of the secretion of Arginine-vasopressine or antidiuretic hormone (vasocontriction and effect Diurétique),
of the synthesis of the endothéline (vasoconstriction),
of the auricular natriuretic Factor (Vasodilatation, action Diurétique),
of the secretion of Prostaglandin S (vasodilatation).

These mechanisms are sometimes contradictory and harmful in the long run (a vasoconstriction involves, for example, an increase in the blood pressure and thus in the post-load, which can raise cardiac failure). The purpose of the treatments suggested are often essential to regularize these compensation mechanisms.

Diagnosis

Functional signs

In the left ventricular insufficiency, one can note a Dyspnée, a Toux, peripheral signs of cardiac bottom Débit (Asthénie, confusional Syndrome, psychomotor deceleration, abdominal pains, nausea S, Vomissement S, Oligurie), a Hémoptysie.
Dans the right ventricular insufficiency, one can note a Asthénie, hepatic pains (hépatalgie) occurring with the effort or permanent, even of the paroxystic hépatalgies (clinical picture near to the Biliary colic).

Clinical signs

In the left ventricular insufficiency, the clinical examination finds signs of the Cardiopathie in question, a Tachycardie; with the cardiac Sounding, a breath of mitral Insufficiency functional; with the pulmonary sounding, rails crépitants, a épanchement pleural.
Dans the right ventricular insufficiency, the clinical examination finds signs of the Cardiopathie in question, a Tachycardie; with the cardiac Sounding, a breath of functional Insufficiency tricuspide, a glare of B2 (second cardiac noise); a Hepatomegaly, a Backward flow hépato-chin-strap, a jugular Turgescence, oedemas of the lower extremities, sometimes of the Ascite.

Complementary examinations

Electrocardiogram

A electrocardiogram is systematically carried out in the search of signs in connection with the responsible Cardiopathie. It will be able to highlight a sinusal tachycardia, signs of left ventricular Hypertrophie or right, turbid of conduction or rate/rhythm (flutter, auricular Fibrillation, ventricular extrasystoles).

Radiograph standard

A pulmonary Radiographie will be able to highlight:

in the left ventricular insufficiency: an increase in size of the cardiac silhouette (cardiomégalie), a vascular redistribution at the pulmonary tops (early stage), fine horizontal spans (lines of Kerley B) translating the lymphatic damning up , a épanchement pleural.
in the right ventricular insufficiency: the cardiac silhouette can be of normal size, an increase in volume of the right and/or left cardiac cavities (function of the responsible cardiopathy).

Cardiac echography

The realization of a cardiac echography is essential. It makes it possible to inform about the causal Cardiopathie, to confirm and quantify cardiac failure and to seek complications (mitral escape, auricular Thrombus intra- , pulmonary arterial Hypertension).

In the event of systolic dysfonction, one will note a reduction in the fraction of shortening (lower than 33%), a reduction in the fraction of ejection (lower than 70-75%), the left ventricle appears dilated and hypokinetic.

In the event of diastolic dysfonction, one will note the absence of dilation of the left ventricle, an increase thickness of his wall, from where an increase in the pressures involving a dilation of the left auricle.

Criteria of Framingham for the diagnosis of cardiac failure

The diagnosis is acquired if two major criteria or a major criterion and two minor criteria are present.

Major criteria

night Dyspnea paroxystic or Orthopnée,
venous distension,
Cardiomégalie,
rails crépitants,
pulmonary edema,
gallop (B3),
increase in the central venous pressure,
Backward flow hépato-chin-strap.

Minor criteria

bilateral edema of the ankles,
night Cough,
Dyspnea of effort,
épanchement pleural,
Hepatomegaly,
Tachycardia (higher than 120 beats per minute),
vital Capacity reduced by 30%.

Major or minor criterion

weight loss higher than 4,5Kg in five days in answer to a treatment of cardiac failure.

Classifications

There exist several ways of classifying a cardiac failure: first of all function on the side of the heart reached (left cardiac failure or right-hand side), and also according to whether the anomaly interests the ventricular ejection (systolic dysfonction) or the filling (one speaks then about diastolic dysfonction).

The classification NYHA is frequently used to quantify and supervise the functional repercussion of cardiac failure for the same individual:

Class I: no the limitation, the ordinary physical-activity does not involve abnormal tiredness, of Dyspnée or Palpitation S,
Classe II: modest limitation of the physical-activity: at ease at rest, but the ordinary activity involves a tiredness, palpitations or a dyspnea,
Classe III: marked reduction of the physical-activity: at ease at rest, but an activity less than with accustomed causes Symptôme S,
Classe IV: impossibility of continuing an physical-activity without embarrassment: the symptoms of cardiac failure are present, even at rest and the embarrassment is increased by any physical-activity.

Causes

Systolic Dysfonction

Left ventricular insufficiency by deterioration of the muscular function

ischemic cardiopathies,
Myocarditis: viral (Coxsackie, HIV), bacterial (acute Rheumatoid arthritis, Typhoid, Légionellose), parasitic (Disease of Chagas),
Cardiomyopathie dilated with coronary healthy: toxic primitive, (alcohol, Anthracycline S), diseases of overload,
diseases of system: érythémateux Lupus disseminated, knotty Periarteritis,
diseases endocriniennes with myocardic attack : thyréotoxicose, Phéochromocytome, Acromégalie, diabetes,
degenerative disease neuromusculaire (Disease of Steinert, dystrophy of Duchenne of Boulogne).

Left ventricular insufficiency by insufficiency of the cardiac pump

overload of pressure: arterial Hypertension, aortic Contracting, Coarctation of the aorta, hypertrophic Cardiomyopathie obstructive,
overload of volume: mitral Insufficiency acute (rupture of rope, dysfonction of pillar, Endocarditis), or chronicle, congenital or acquired inter-ventricular Communication (Myocardial infarction),
overload in pressure and volume: aortic Insufficiency acute (Endocarditis, aortic Dissection), or chronicle, persistence of the arterial Channel.

Rhythmic Cardiopathies

auricular Fibrillation and others supra-ventricular tachycardias,
ventricular Tachycardia (ratrement),
turbid of conduction.

Cardiac failure with high flow

Hyperthyroïdie,
chronic Anemia,
deprives of Vitamine B1,
arteriovenous dent congenital or acuquise,
Maladie of Paget.

Right ventricular insufficiency

secondary with an advanced left ventricular insufficiency,
mitral Contracting tight,
pulmonary arterial Hypertension primitive or secondary,
right Myocardial infarction of the ventricle,
Dysplasie right arythmogene of the ventricle.

Diastolic Dysfonction

concentric replanning of the left ventricle: Cardiomyopathie S obstructive primitives or not, cardiomyopathies secondary with an overload of pressure (arterial Hypertension systolo-diastolic, aortic Contracting),
ischemic cardiopathy,
cardiopathy diabetic,
Amylose,
Hémochromatose,
diseases of overload.

Assumption of responsibility

The objectives of the treatment are to restore hemodynamic correct, to manage the possible starting factors, to treat the causes if possible.

Hygiéno-dietetic rules

taken of load by the adapted Physical-activities: moderated, adapted and regular physical-activity,
little salted mode,
hydrous restriction in the event of Hyponatrémie of dilution (500 to 750 ml per day),
dealt with cardiovascular of the Risk factors.

Systolic cardiac failure

Diurétique S: mainly diuretic of the handle, or the Spironolactone in the severe forms,
Inhibiting of the enzyme of conversion indicated at all the stages,
Beat-blocking S in the absence of counter-indications and of acute push of cardiac failure,
treatment Anticoagulant per bone in the event of auricular Fibrillation or of Thrombus,
can also be used the Digitalique S or the Amiodarone, but their place is discussed.

Diastolic cardiac failure

no indication with the désodé mode,
Diurétique S (action on the preload),
Beat-blocking S or inhibiting calcic.

Evolution and complications

The evolution and the forecast depend on pathology responsible for cardiac failure.
L' evolution can be enamelled complications of which most frequent are the turbid rate/rhythm (especially the auricular Fibrillation), the accidents thromboembolic, the Impaired renal function.

The factors of acute decompensation are the Anémie, a Infection, a pulmonary Embolie, the respiratory Insuffisance, a hypo or Hyperthyroïdie, an excess of salt, the stop of a treatment.

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