Heart Failure Phatophysiology

When cardiac output is insufficient to meet demands of the body, compensatory mechanism operate to improve cardiac output. Although the compensatory mechanism may initially increase cardiac output, they eventually have a damaging effect on pump function.

Compensatory mechanisms include:
- Increased heart rate
- Improved stroke volume
- Arterial vasoconstriction
- Sodium and water retention
- Myocardial hypertrophy

In heart failure, stimulation of the sympathetic nervous system represents the most immediate compensatory mechanism. Stimulation of the androgenic receptor causes and increase in heart rate and vasoconstrictions


SIGN AND SYMPTOMS
The sign and symptoms of heart failure can be considered in the context of these components of the syndrome:
- Failure of the left ventricles as pump with decreased tissue perfusion and pulmonary venous congestion
- Failure of the right ventricles as pump with systemic venous congestion


LEFT VENTRICULAR HEART FAILUER
Left ventricular failure is associated with decreased cardiac output and elevated pulmonary venous pressure. Decreased blood flow to major body organs can cause organ failure, especially renal failure. It may appeared clinically as:
DECREASED CARDIAC OUTPUT
- Fatigue
-Weakness
-Oliguria during the day
-Angina
-Confusion, restlessness
-Dizziness
-Tachycardia, palpitations
-Pallor
-Weak peripheral pulses
-Cool extremities
PULMONARY CONGESTION
-Hacking cough, worse at night
-Dyspnea / breathlessness
Crackles or wheezes in lung
-Frothy pink-tinged sputum
-Tachypnea

RIGHT VENTRICULAT HEART FAILURE
Right ventricular failure is associated with increased systemic venous pressures. Sign and symptoms are:

-Jugular (neck vein) distensions
-Enlarged liver and spleen
-Anorexia and nausea
-Dependent edema (legs and sacrum)
-Distended abdomen
-Swollen hands and fingers
-Polyuria at night
-Weight gain
-Increased blood pressure or decreased (from excess volume) blood pressure (from failure)

On inspection nurse assesses the neck veins for distension. The nurse also measures the client stomach. The collection of fluid in the abdomen can reach volume more than 10L

In addition, the nurse examines the client for dependent edema. In ambulatory client, edema is normally located in the ankles and legs.

However, when clients is restricted to bed rest, the sacrum is dependent and edema accumulates there. Edema is extremely unreliable sign of the heart failure so accurate daily weights are needed to documents fluid retention.

Weight is the most reliable indicator of fluid gain or loss