Cardiac DZ,

• Heart murmurs


  A shhh sound heard over or around the normal lub-dub sounds. The lub-dub sounds are caused by the closing of the A-V valves and the semilunar valves, respectively. A murmur occurs from leakage of blood through the valves, or turbulence from an abnormal narrowing or enlargement.
• Murmurs


  • Categorized by their intensity, location best heard and placement in the cardiac cycle
• Intensity of murmurs


  Graded on a scale from 1-6. A 1/6 murmur is a very quiet and low intensity. A 6/6 murmur is the loudest possible murmur and can be heard or palpated without a stethoscope, close to the patient.
• Location of murmur


  The murmur is often loudest where that malfunctioning valve is anatomically located in the patient.
• Occurrence of murmur in cardiac cycle

  If the murmur is heard during the lub-dub, it is considered a systolic murmur because it is occurring during contraction. If the murmur is heard during the pause between lub-dubs, it is called a diastolic murmur because it is occurring during relaxation.
• Arrhythmia


  An abnormality in the rate or rhythm of the heartbeat. Different types of heart diseases may cause different sounding arrhythmias.
• Canines have a normal sinus arrhythmia related to the respiratory cycle and is not a sign of disease. Their heart rate increases during inspiration and decreases during expiration.
• Auscultation of the lungs

  Listen to both the inspiratory and expiratory sounds and observe the rate and effort when breathing. Abnormal sounds may be defined as crackles, wheezes, stridor, stertor, muffled, or normal.
• Palpate pulses


  Weak, thready, bounding pulses or irregular pulses may indicate underlying heart disease. Absence of a palpable pulse (or a significant change in pulse quality) with an audible heartbeat is called a pulse deficit.
• Capillary refill time (CRT)


  Abnormal mucus membrane color or a prolonged CRT may indicate cardiovascular disease. Mucous membrane color can vary from bright brick red to pale to blue (cyanosis) depending on the type of cardiovascular disease present. Depending on the blood pressure and cardiac output, the CRT can be prolonged (greater than 2 seconds).
• Diagnostics for cardiovascular disease

  • Radiography
  • Laboratory tests
  • Echocardiogram
  • Electrocardiogram
  • Blood pressure
• Radiography


  Standard thoracic radiographs to evaluate the cardiovascular system are a right lateral view and a D/V view. Radiographs can determine overall heart size and shape, presence of fluid in the lungs (pulmonary edema), presence of fluid around the lungs (pleural effusion), and engorgement of blood vessels in the lung (pulmonary congestion).
• Laboratory tests


  Initial blood work and urine testing are routinely performed. Testing rarely defines cardiovascular disease, except in heartworm cases and cases where heart problems are secondary to metabolic disorders and endocrinopathies. Blood work and urinalysis can show evidence of organ congestion that occur with right-sided heart failure, and they are essential to run routinely when an animal is on any cardiac medication. Some specialized tests looking for cardiac biomarkers are on the rise in veterinary medicine.
• Echocardiogram


  An ultrasound of the heart, typically performed by a cardiologist or an internist to diagnose any structural or functional abnormalities of the heart.
• Electrocardiogram (ECG)


  Measures the electrical activity of the cardiac muscle cells. ECGs are routinely used to monitor for arrhythmias and during anesthetic procedures. For patients suspected of an intermittent arrhythmia, a Holter monitor may be prescribed to collect continuous ECG data for several days.
• ECG tracing


  P wave = a small upward deflection representing the depolarization of the atria

  QRS complex = a large upward deflection representing the depolarization of the ventricles

  T wave = a small upward or downward deflection representing the repolarization of the ventricles
• Blood pressure


  The pressure with which the blood pushes against the walls of the vessels, measured in millimeters of mercury (mm Hg) or torr. Can be measured directly or indirectly.
• Direct arterial blood pressure monitoring

  Considered the gold standard, using an arterial catheter to allow continuous monitoring of systolic, diastolic and mean blood pressure.
• Indirect arterial blood pressure monitoring


  Commonly performed in general practice, using a cuff on an extremity with either a Doppler and sphygmomanometer or oscillometric device.
• Systolic pressure


  The pressure of the blood in the arteries during ventricular systole, when arterial pressure is at its highest.
• Diastolic pressure


  The pressure of the blood in the arteries during ventricular diastole, when arterial pressure is at its lowest.
• Mean arterial pressure


  The average pressure of the blood in the arteries over the entire cardiac cycle.
• Pulse pressure


  The difference between systolic and diastolic pressure.
• Factors affecting blood pressure

  Cardiac output, blood volume, peripheral resistance, and blood viscosity
• Homeostatic mechanisms maintaining blood pressure


  Baroreceptors respond to changes in arterial pressure and send signals to the cardiac and vasomotor centers of the brain, which then send impulses via the autonomic nervous system to the heart and vessels to adjust cardiac output or blood vessel diameter. Hormones like epinephrine, norepinephrine, ADH, and angiotensin also affect blood pressure.
• Congestive heart failure


  Occurs when the heart is unable to keep up with the demands put on it, resulting in fluid backing up abnormally in the lungs, thorax, abdomen or abdominal organs.
• Left-sided congestive heart failure


  Fluid backing up in the lungs, causing coughing, dyspnea, exercise intolerance and cyanosis.
• Right-sided congestive heart failure


  Fluid backing up in the abdomen, causing ascites, an engorged liver, spleen or generalized edema in the limbs.
• Dilated cardiomyopathy (DCM)


  A progressive disease characterized by enlargement and weakening of the heart muscle.
• Fluid in the lungs

  • Causes coughing, dyspnea, exercise intolerance and cyanosis
• Right sided CHF


  • Fluid backing up in abdomen, causing ascites
  • Engorged liver, spleen or general generalized edema in the limbs
  • Swollen belly, muscle wasting and decreased energy
• Patients with CHF


  • Cyanosis, a heart murmur, increased heart rate, tracheal sensitivity, jugular pulses and crackles in their lung fields
• Diagnosing CHF


  1. Chest x-rays used to diagnose pulmonary edema from left sided CHF

  2. Ultrasound of the abdomen and heart used to diagnose right sided congestive heart failure

  3. Abdominocentesis may be performed to get a sample of the ascites for diagnostics and to provide relief if fluid was causing discomfort
• Treating CHF


  1. Diuretics (e.g. Lasix)

  2. Inodilator (e.g. Pimobendan)

  3. ACE inhibitor (e.g. Enalapril)
• With treatment, patients can have good quality life for another 1-2 years after developing CHF
• Dilated Cardiomyopathy (DCM)


  Progressive disease characterized by loss of contractility of the heart muscle
• Causes of DCM


  • Unknown, but may be secondary to dietary deficiency (e.g. Taurine deficiency in cats), infection, immune dysfunction, or any other cause of heart muscle trauma
• Effects of DCM


  • Heart muscle becomes weak and thin, resulting in dilation of the chambers; the thin muscle can no longer contract efficiently and pump blood normally
• DCM is more common in large breed dogs, especially Doberman Pinchers and Cocker Spaniels
• Prognosis is better with taurine-deficient disease if caught early and supplementation initiated