Cheyne-Stokes Respiration

This form of respiration is also known as periodic breathing which is characterized by cycles of shallow respirations that increase in depth and rate causing severe hyperpnea. Hyperpnea is followed by decreasing depth and rate of respiration and then the period of apnea that lasts foe almost 15 seconds. This type of respiration is a symptom of congestive heart failure and some CNS diseases. The respiration most often occurs during sleeep and often reported by others because patient is not aware of cheyne stokes respiration.

Causes of Dyspnea

Dyspnea is commonly defined as labored or difficult respiration. Dyspnea can be also defined as unpleasant awareness of one`s breathing.

Causes of Chronic Dyspnea

• Heart Failure
• Pulmonary Disease
• Anxiety
• Obesity
• Poor Physical Fitness
• Pleural Effusions
• Asthma

Causes of Acute Dyspnea

• Airway Obstruction
• Pneumonia
• Pulmonary Embolism
• Pneumothorax
• Hyperventilation
• Acute Pulmonary Edema

Causes of Dyspnea on Exertion

• Congestive Heart Failure
• Physical Deconditioning
• Chronic Pulmonary Disease

The Causes of Chest Pain

1. Ischemic Causes of Chest Pain

• Angina Pectoris of Myocardial Infarction (Acute Coronary Syndrome)
• Aortic Stenosis
• Hypertrophic Cardiomyopathy
• Severe Systemic Hypertension
• Aortic Regurgitation
• Severe Anemia or Hypoxia

     2. Non Ischemic Causes of Chest Pain

• Mitral Valve Prolapse
• Aortic Dissection
• Pericarditis

      3. Gastrointestinal Causes of Chest Pain

• Esophageal Spasm
• Esophageal Reflux
• Esophageal Rupture
• Peptic Ulcer Disease

     4. Psychogenic Causes of Chest Pain

• Anxiety
• Depression
• Cardiac Neurosis
• Self Gain

      5. Neuromusculoskeletal Causes of Chest Pain

• Thoracic Outlet Syndrome
• Degenerative Joint Disease of Cervical or Thoracic Spine
• Chostochondritis (Tietze Syndrome)
• Herpes Zoster
• Chest Wall pain and Tenderness

     6. Pulmonary causes of Chest Pain

• Pulmonary embolus 
• Pneumothorax
• Pneumonia with Pleural Involvement

The Electrical Activity of Heart

The Atria and the ventricles are the chambers of the heart which contract and relax during each cardiac cycle. The contraction of these chambers is controlled by wave of depolarization which travels through muscular walls of these chambers. The contraction is followed by relaxation of the chambers which is also known as repolarization.

The ECG machine records both of these phases of electrical activity. The atrial depolarization is triggered in SA node of the heart which is also known as sinoatrial node. The special conducting system of heart starts from the SA node which is located in right atrium. The atria and ventricles are separated by fibrous non conducting tissue. The electrical impulse can only travel through specialized conducting tissue from upper to lower chambers. In a normal heart electrical impulse can only travel from atria to ventricles through AV node. The AV node is located in the interatrial septum near the opening of coronary sinus. The depolarizing signal gets slightly delayed in AV node. This gives some time to ventricles to fill with blood pushed by atrial contraction. The depolarizing current further travels through bundle of His. The bundle of His is located in Interventricular septum which further divides into right and left budle branches. Th right and left budle branches supply right and left ventricles respectively.

The first part of ventricular muscle mass to depolarize is interventricular septum and the movement of depolarization is always from left to right bundle branch. The wave of depolarization always spreads from endocardium to epicardium of ventricular wall while repolarization takes place in the opposite direction that is from epicardium to endocardium.

ECG - Left Ventricular Hypertrophy

There are many ECG criterion s which are used to diagnose LVH. The most commonly used criteria for diagnosing LVH is Sokolow-Lyon criterium. 

• (Height of R wave in V5 or V6 + Depth of  S wave in V1)  >35 mm (≥ 7 large squares)  signifies LVH 

 ECG Image Depicting LVH

LV Strain Pattern

• Tall R waves in leads V5 and V6 with ST segment depression T wave inversion 
• Deep S waves with ST segment elevation in V1 (rare) also signifies Left Ventricular Hypertrophy. LVH  strain pattern is often seen in patients with systemic overload of left ventricle. This overload is seen in patients having aortic stenosis, systemic hypertension and hypertrophic cardiomyopathy.