Left & Right-sided Heart Failure

Etiology of Left-sided CHF

·         Left ventricular failure can result from:

1)     Volume overload: Occurs with regurgitant mitral or aortic valves, and high-output states such as anemia & hyperthyroidism

2)     Pressure overload: occurs with hypertension & aortic stenosis

3)     Loss of muscle mass: examples include left ventricular MI & inflammatory diseases like lupus

4)     Loss of contractility: Can occur as a result of bacterial or viral infection (i.e. Myocarditis), or from certain poisons & toxins

5)     Restricted filling: examples include mitral stenosis and pericardial disease

 

Manifestations of Left-sided CHF

Forward effect: decreased CO- ¯ systemic blood flow

-       ¯blood flow to brain- ¯level of consciousness – faint

-       ¯blood flow to SKM- Muscle fatigue & weakness

-       ¯blood flow to kidney- ¯urine output – acute kidney failure

-       ¯blood flow to GI-  ¯ support to GI activity (peristalsis)

·         Manifested as fatigue, weakness, dyspnea, exercise intolerance & cold intolerance, cyanosis

·         Compensatory manifestations: tachycardia, pallor, daytime oliguria, nocturia, polycythemia

·         Uncompensated manifestations: cyanosis, anorexia, and cachexia

· Backup effect: pulmonary congestion

- Hard to receive pulmonary blood flow from lungs® pulmonary hypertension ® pulmonary edema: shift of fluid out into interstitial space

-Leads to ↑ capillary pressure and edema, fluid is force into the alveoli® interferes with gas exchange ® hypoxemia (¯oxygen supply) & predisposes to pneumonia

-       ↑ afterload @ right ventricle: right ventricle work harder ®↑ risk of right-side failure.

 

Etiology of Right-Sided CHF

Right-sided CHF can be caused by any condition that impairs flow into the lungs including:

1)     Left Ventricular Failure: Pulmonary edema ↑ the afterload on the right ventricle (i.e. Hypoxic vasoconstriction)

2)     Loss of muscle mass: Right ventricular or inferior MI

3)    Tricuspid valve incompetence

4)    Pulmonary (SL) valve stenosis

5)     Congenital defects: pulmonary obstruction or shunts can ↑ the workload on the right ventricle causing it to eventually fail

6)     Respiratory disease: COPD, bronchitis, asthma

-       Damage to circulation – pulmonary hypertension - ↑ afterload

-       Cor pulmonale – right side failure cause of Resp. disease (COPD)

®      Commonly associated with smoking

®      Impaired ventilation (COPD) causes pulmonary vasoconstriction that ↑ afterload and often results in failure.

®      Pulmonary embolism also causes cor pulmonale

Forward effects: decreased CO

-       Less blood flowing to lungs ® ¯ gas exchange ® systemic hypoxia

-       Left side works harden in response to ¯ blood flow (¯ CO) ® left side failure

Backup effects: congestion in systemic circulation ® peripheral edema

-       ↑ Hydrostatic pressure in systemic vein

®      Swelling of jugular vein – i.e. Elevated jugular venous pressure® congestion into the cranium can create CNNS symptoms such as headache (¯blood flow away from head) or visual disturbance, flushed face.

®      ↑ risk of varicose vein

®      Systemic edema: bulging of veins

-       Hepatomegaly & splenomegaly: fluid accumulation in the liver or spleen causes distention and upper quadrant pain

®      Liver swells up – Hepatomegaly

®      Spleen swells up – splenomegaly