SPECIAL SENSES

• Heart


  Hollow muscular organ
• Location of the heart


  • Located in the mediastinum (thoracic cavity, center of chest)
  • Weighs approximately 255g (F) to 310g (M)
  • Base - upper portion (left 2nd ICS)
  • Apex - lower portion (5th ICS LMCL)
• Chambers of the heart


  • Right atrium (RA)
  • Right ventricle (RV)
  • Left atrium (LA)
  • Left ventricle (LV)
• Major blood vessels


  • Superior vena cava (connected to RA, brings deoxygenated blood)
  • Inferior vena cava (delivers deoxygenated blood from inferior part of body towards heart)
  • Pulmonary trunk (connected to RV, bifurcates into left and right pulmonary arteries)
  • Aorta (ascending aorta, aortic arch, descending aorta - thoracic aorta, abdominal aorta)
• Valves


  • Atrioventricular (AV) valves (prevent backflow of blood into atria when ventricles contract, located between atria and ventricles)
  • Tricuspid valve (3 cusps, connected to RA and RV)
  • Bicuspid/mitral valve (2 cusps, connected to LA and LV)
  • Semilunar (SL) valves (prevent backflow of blood into ventricles, located on major artery and vein of heart)
  • Pulmonary semilunar valve (opens and closes when RV contracts, allows blood flow to lungs, located in pulmonary trunk)
  • Aortic valve (located in aorta)

  
• Septum


  • Interatrial septum (separates RA and LA)
  • Interventricular septum (separates RV and LV)
• Papillary muscles


  • Connected to chordae tendineae (string-like extensions of valves that help open/close valves and anchor AV valves)
  • Attached to trabeculae carnae of ventricles (aids in pumping blood, venous network below myocardium)

  
• Layers of the heart


  • Epicardium/visceral pericardium (outermost covering, provides protection)
  • Parietal pericardium (layer covering pericardial cavity)
  • Myocardium (thickest, middle layer, contains cardiac muscles)
  • Endocardium (innermost layer, contains endothelial cells, reduces friction)
• Electrical conduction of the heart


  1. Sinoatrial node/pacemaker (generates electrical stimulus, regulates contraction and rate)

  2. Atrioventricular node (receives charges from SA node, slows down impulses)

  3. Atrioventricular bundle (Bundle of His, bifurcates into bundle branches)

  4. Bundle branches (stimulate RV and LV)

  5. Purkinje fibers (cause ventricular contraction)

  
• Electrocardiogram (ECG)


  • Records electrical activities of heart
  • P wave (atrial depolarization/contraction)
  • QRS complex (ventricular depolarization/contraction, atrial repolarization masked)
  • T wave (ventricular repolarization/relaxation)

  
• 2D echocardiogram


  Used to know structural defects of heart
• Cardiac cycle


  • Filling and emptying of heart chambers
  • Repetitive contraction and relaxation of heart chambers
  • Systole (contraction of atria or ventricles)
  • Diastole (relaxation of atria or ventricles)

  
• Pulmonary circulation


  • Purpose is to oxygenate blood
  • Managed by right side of heart
  • Moves blood from heart to lungs
  • Has lower pressure compared to systemic circulation

  
• Systemic circulation


  • Purpose is to transport oxygenated blood to body
  • Managed by left side of heart
  • Moves blood from heart to body

  
• Heart sounds


  • S1 (lub, closure of AV valves, beginning of systole)
  • S2 (dub, closure of SL valves, beginning of diastole)
  • S3 (ventricular gallop, early diastole)
  • S4 (atrial gallop, late diastole)
  • Murmurs (pathologic heart sounds from turbulent blood flow)
• Cardiac output


  • Volume of blood ejected by ventricles in one minute (stroke volume x heart rate = 5-6 L/min)
  • Stroke volume (amount of blood ejected from left ventricle per contraction, ~70 ml)
  • Heart rate (number of beats per minute, 60-100 bpm)

  
• Factors affecting stroke volume


  • Preload (volume of blood in ventricles at end of diastole)
  • Afterload (resistance left ventricle must overcome to pump blood to system)
  • Synergy contraction
  • Compliance/distensibility of ventricles
  • Contractility of myocardium
  • Autonomic nervous system stimulation (sympathetic increases, parasympathetic decreases)
• Carotid artery pulse


  • Common carotid arteries bifurcate into internal and external
  • Located between trachea and SCM
  • Centrally located arterial pulse

  
• Jugular venous pulse


  • Internal jugular veins run parallel to carotid artery
  • External jugular vein runs perpendicular to SCM, can be easily seen
  • Correlates with hemodynamics in right side of heart
  • Jugular venous pressure reflects right atrial pressure, determines central venous pressure

  
• Vagus nerve


  (CN X)
• Neck vessels


  • Carotid artery pulse
  • Common carotid arteries
  • Bifurcates into internal and external carotid arteries
  • Located between trachea and SCM
  • Centrally located arterial pulse

  
• The carotid artery is to be checked immediately if a patient is unconscious in order to determine if the heart or sinoatrial node is still working
• Jugular venous pulse


  • Internal jugular veins
  • Runs parallel to the carotid artery
  • External jugular artery
  • Runs perpendicular to the SCM
  • Can easily be seen
  • Correlates with the hemodynamics in the right side of the heart
  • Jugular venous pressure (JVP)
  • Reflects right atrial pressure
  • Determines the central venous pressure (CVP)

  
• Doctors directly place catheters on the right atrium to detect the central venous pressure to determine if the patient has heart failure
• Subjective data: History of present illness


  • Chest pain
  • Tachycardia / palpitations
  • Easy fatigability
  • Dyspnea
  • Orthopnea
  • Cough
  • Dizziness
  • Bipedal edema
  • Abdominal pain / heartburn
• Always investigate further when assessing chest pains because the cause may either be pulmonary or cardiovascular related
• Remember to check both the pulmonary and cardiovascular status of the patient

  
• Subjective data: Past medical history


  • Congenital / acquired heart defects
  • Rheumatic fever
  • Heart surgery
  • ECG
  • Dyslipidemia
• Rheumatic fever


  History of tonsillitis (treated or not / recurrent). If left untreated, the microorganisms that cause tonsillitis may travel to other parts of the body and can lead to rheumatic heart disease (RHD)
• Dyslipidemia


  Elevated cholesterol levels (Triglycerides, LDL, VLDL, cholesterol)
• Subjective data: Family history


  • Hypertension (HPN)
  • Myocardial infarction (MI)
  • Coronary artery disease (CAD)
  • Elevated cholesterol levels
  • Diabetes mellitus (DM)
• Coronary artery disease (CAD)


  • Atherosclerosis (Plaque of fat in arteries)
  • Arteriosclerosis (Hardening of arteries)
• Diabetes mellitus (DM)


  Patients with diabetes may also have hypertension because there is increase in blood viscosity = increase in BP
• Subjective data: Social history


  • Smoker
  • Alcohol intake
  • Illicit drugs
  • Stressor
  • Exercise
  • Limitation of ADLs
  • Number of pillows
  • Sexual activity
• Assess the heart and neck vessels immediately after thorax and lungs assessment

  
• Explain the need to expose the anterior chest
• Explain necessary positions during examination (Supine, sitting, left lateral position)
• Explain that you will be listening to the heart in different places which does not necessarily mean that anything is wrong
• In women with large breasts, ask the patient to pull her breast upward and to her side when you are auscultating for heart sounds
• Understand the anatomy and function of the heart and major coronary vessels to identify and interpret heart sounds and ECGs accurately