Friday, January 20, 2012

Right-Sided Heart Failure


Reduction of right ventricular output for an increased atrial pressure is called right-sided heart failure.

MORPHOLOGY (Right-sided heart failure)
Organs affected: Liver, spleen, kidneys, subcutaneous tissues, brain, portal area of venous drainage.

Liver: Changes in the liver tissue are the following:

Chronic passive congestion:
It has two components as following:
  • Nutmeg pattern: The central region of hepatocytes become congested appearing red while the peripheral region is uncongested appearing yellow. This red and yellow mottling gives the liver a characteristic appearance called nutmeg pattern.
  • Ischemic atrophy: Congestion of the central vein causes diminished rate of blood flow through the lobule, leading to chronic oxygen  deficiency in the liver cells in the central region of the lobule which results in ischemic atrophy of the liver cells in the congested central region of the lobule.

Central hemorrhagic necrosis:
In severe congestive cardiac failure, hemorrhages into the hepatic cords occur producing necrosis of the liver cells, this is called central hemorrhagic necrosis.

Cardiac sclerosis:
It is a complication of severe cardiac failure and is characterized by fibrosis of the central areas of hepatic lobules and is termed as cardiac sclerosis or cardiac cirrhosis.

CLINICAL FEATURES

Acute right ventricular failure:

Acute right ventricular failure occurs in:
  • Massive pulmonary embolism: Acute right ventricular failure occurs when massive pulmonary embolus becomes impacted in and obstruct the outflow tract of the right ventricle and main pulmonary artery. This results in arrest of the circulation and sudden death.
  • Cardiac temponade: Acute right ventricular failure occurs when fluid accumulates in pericardial cavity that interferes the right ventricular diastolic filling, resulting in decreased right ventricular output; the condition called cardiac temponade.

Chronic right ventricular failure:
Most commonly occurs secondary to left ventricular failure and is manifested clinically by systemic venous congestion such as:
  • Liver is enlarged and tender: Enlargement due to congestion and tenderness due to stretching of liver capsule.
  • Peripheral edema: Occurring in dependent areas – the ankles in ambulatory patients and the sacrum in recumbent ones.
  • Pleural effusion, pericardial effusion or ascites.

INVESTIGATIONS

ECG: ECG may show:
  • Right or left ventricular hypertrophy
  • Myocardial ischemia or infarction
  • Arrhythmia

X-ray Chest:
  • Hilar congestion
  • Bat’s wings appearance in acute pulmonary edema (opacities tend to spread in a butterfly manner from the hilum, periphery is usually clear)
  • Cardiomegaly
  • Evidence of pulmonary hypertension
  • Pleural effusion
  • Pneumonia as a precipitating factor may be evident.

Echocardiography:
Echocardiography is a very important tool for the diagnosis and cause of heart failure. It may demonstrate:
  • Systolic or diastolic impairment of left or right ventricle.
  • Valve disease.
  • Regional wall motion abnormalities in ischemic heart disease.
  • Cardiomyopathy
  • Intracardiac thrombus
  • Ejection fraction

TREATMENT
  • Diuretics e.g. frusemide.
  • Vasodilators e.g. ACE inhibitors 
  • Digitalis

Thursday, January 19, 2012

Symptoms of Left Heart Failure and Signs

Left Heart Failure Symptoms are:

Dyspnea
A sense of breathlessness, initially on exertion then on rest also. The dyspnea is maximal when congestion of the lung is greatest as in exercise and lying flat.

Dyspnea on exertion
In early stage syspnea is noticeable during physical activity and is called dysnea on exertion. It results from increased venous congestion during physical activity.

Orthopnea
Dyspnea on lying flat is called orthopnea. It results from increased amount of venous return to thorax from lower extremities when patient is in lying position. Heart is unable to pump all of this venous return that leads to lung congestion and dyspnea.

Paroxysmal nocturnal dyspnea
Dyspnea during sleep which awakens the patient with severe breathlessness, accompanied by a choking sensation and coughing is called paroxysmal nocturnal dyspnea. It also results from increased venous congestion as the patient is lying on bed.

Signs of Left Heart Failure:

Tachycardia, cardiomegaly, third heart sound, and fine crepts at the lung bases. Chronic dilation of left atrium may also occur which may be associated with atrial fibrillation.

Low Versus High Cardiac Output Failure


Low output failure
Low cardiac output at rest or during exertion characterizes heart failure caused by common conditions such as congenital, valvular, rheumatic, hypertensive, coronary and cardiomyopathic diseases. Low output failure presents with evidence of systemic vasoconstriction such as cold, paler or cyanotic extremities. Pulse pressure is low.

High cardiac output failure
Conditions that are associated with a very high cardiac output such as anemia, beriberi, paget’s disease of bone and thyrotoxicosis may lead to or precipitate heart failure.

To understand basic pathogenesis of heart failure of each side of the heart is studied separately.

LEFT-SIDED HEART FAILURE
Reduction in the left ventricular output for a given pulmonary venous pressure is called left sided heart failure.

CLINICAL FEATURES
The clinical changes associated with left ventricular failure depend on whether failure is acute or chronic.

Acute left ventricular failure:
  • Acute forward failure: An acute severe decrease in cardiac output leads to cardiogenic shock.
  • Acute backward failure: Failure of the left ventricle to pump the pulmonary venous return causes increased hydrostatic pressure in pulmonary capillaries with transudation of fluid into the alveolar space, called pulmonary edema. Clinically, pulmonary edema is manifested as dyspnea with cough productive of pink frothy sputum. Edema fluid produces crepitations on auscultation.

Chronic left ventricular failure:
  • Chronic forward failure: Decreased cardiac output results in decreased tissue perfusion. Decreased renal blood flow stimulates rennin-angiotensin system and aldosterone formation which causes sodium and water retention from kidney. This sodium and water retention increase blood volume, therefore increasing venous return to already weak heart, resulting in congestion of lungs.
  • Chronic backward failure: Inability of heart to pump all the venous return leads to passive venous congestion in the lung which if prolonged induces fibrous thinking of alveolar septa. The thickened alveolar septa intern increases resistance to lung expansion, causing dyspnea.

Types of Heart Failure and Causes

The heart failure may be classified in several ways.
  1. Acute versus chronic
  2. Left versus right and biventricular or congestive heart failure (CCF)
  3. Forward versus backward
  4. Systolic versus diastolic
  5. low output versus high output

ACUTE VERSUS CHRONIC HEART FAILURE
Acute heart failure
Heart failure developing suddenly in hours a days in a previously asymptomatic patient is called acute heart failure.

Causes
The causes of acute heart failure occur when a previously normal person suddenly develops a serious anatomical or functional abnormality and time is not sufficient for compensatory mechanisms to operate such conditions are:
  • Massive acute myocardial infarction.
  • Tachyarrhythmias with very rapid heart rate.
  • Rupture of valve secondary to infective endocarditis.

Chronic heart failure
Heart failure developing gradually is called chronic heart failure. In this type of failure a variety of compensatory changes may take place in early phase to improve cardiac function. These adoptive mechanisms allow the patient to adjust and tolerate not only the anatomic abnormality but also a reduction in cardiac output with less difficulty.

LEFT VERSUS RIGHT AND BIVENTRICULAR OR CONGESTIVE HEART FAILURE

Left sided heart failure
The left sided heart failure is characterized by a reduction in effective left ventricular output for a given pulmonary venous or left atrial pressure.
An acute increase in left atrial pressure may cause pulmonary congestion or pulmonary edema, while chronic increase in left atrial pressure leads to reflects pulmonary vasoconstriction which protects the patient from pulmonary adema at the cost of increasing pulmonary hypertension (as a compensatory mechanism).

Causes of left heart failure
  • Ischemic heat disease (commonest)
  • Systemic hypertension
  • Mitral and aortic valve disease
  • Cardiomyopathies

Right side heart failure
Right-sided heart failure in characterized by reduction in right ventricular output for any given right atrial pressure.
Causes of right heart failure
  • Secondary to left heart failure (most common)
  • Chronic lung disease (Causing cor-pulmonale)
  • Pulmonary embolism or pulmonary hypertension
  • Tricuspid and pulmonary valve disease
  • ASD & VSD
  • Right ventricular cardiomyopathy

Biventricular or congestive cardiac failure (CCF)
When both sides of heart are involved, features of both right and left heart failure are present. In most of the patient right heart failure is a result of preexisting left heart failure.

FORWARD VERSUS BACKWARD FAILURE

Forward failure
In some patients with cardiac failure predominant problem is an inadequate cardiac output that leads to diminished perfusion of vital organs, leading to ischemia of these organs this is called forward failure. Ischemia of brain causes mental confusion, ischemia of skeletal muscles leads to weakness, ischemia of kidneys causes sodium and water retention leading to symptoms of heart failure.

Backward Failure
In some patients cardiac failure presents mainly with features of damming of blood into venous system such as lung congestion in left heart failure and congestion of liver, spleen and other areas in right heart failure.

SYSTOLIC VERSUS DIASTOLIC FAILURE

In majority of patients heart failure is due to combine systolic and diastolic dysfunction, however isolated systolic or diastolic dysfunction may be present.

Systolic Failure
Heart failure may develop as a result of impaired myocardial contraction (systolic dysfunction). The most common cause of systolic ventricular dysfunction is ischemic heart disease usually after myocardial infarction. The left ventricle is usually dilated and fails to contract normally resulting in symptoms of predominantly forward failure.

Diastolic Failure
Heart failure may develop due to poor ventricular filling caused by impaired ventricular relaxation (diastolic dysfunction). The most common cause is left ventricular hypertrophy as a result of hypertension and coronary artery disease. Other causes of diastolic dysfunction are hypertrophic and restrictive cardiomyopathy, diabetes and pericardial disease.