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Author: Brian Downey, M.D.

1. Anatomy & Physiology

1.1. The Cardiac Cycle

  • Cardiac Components
  • Cardiomyctes - contraction
  • Conduction System - electrical system
  • Valves - regulate direction of blood flow

1.2. Cardiac Cycle

  • Systole - contraction
  • Diastole - relaxation

1.3. Cardiac Valves

Right Left
A-V Tricuspid Mitral
Semilunar Pilmonic Aortic

1.4. Heart Sounds

  • First - Closure of A-V Valves
  • Second - Closure of Semilunar Valves

1.5. Electrocardiography - recording of cardiac electrical impulses

  • P Wave - atrial depolarization
  • QRS - ventricular depolarization
  • T Wave - ventricular repolarization

2. Cardiovascular Diseases

CV diseases kill 1 million Americans per year (#1 killer), 42% of all deaths, and more lives than the next leading 7 causes of death combined.

2.1. Ischemic CV Disease

2.1.1. Location

  • Coronary arteries
  • Cerebral arteries
  • Peripheral arteries

2.1.2. Ischemia vs. Infarcation

  • Ischemia = transient, from partial occlusion
  • Infarction = permanent, from total occlusion

2.1.3. Symptoms of Ischemia

  • Angina
  • Transient Ischemic Attack (TIA)
  • Associated symptoms of Angina (breathlessness, nausea and vomiting, diaphoresis, palpitations)

2.1.4. Unstable Angina - avoid elective procedures!!!

  • New onset
  • Crescendo
  • Rest
  • Treatment:
    • I.V. Medicines
    • Angioplasty (PTCA)
    • Coronary Artery Bypass Grafting (CABG)

2.1.5. Myocardial Infarction (MI) - avoid elective procedures for 3-6 months after MI

  • Common medications:
    • Anti-anginals (including Nitroglycerine)
    • Anti-Hypertensives
    • Cholesterol lowering medicines
    • Anti-Coagulants
  • Use of medicines in CAD patients Peri-Procedure
    • Except for anticoagulants, patients with CAD should continue their meds prior to Dental visit
    • Patients should be specifically told to continue their medicines
  • Care of Patients with CAD
    • Assess history of recent symptoms
    • Contact Primary Care Doctor for questions
    • Minimize stress during procedures
    • Patients with CAD alone, or CABG, do not need antibiotic prophylaxis
  • Management of Chest Pain during Procedures
    • Discontinue procedure
    • Give patient Nitroglycerine
    • To emergency Room if no relief after 3 NTG
    • Notify patient's primary doctor

2.2. Valvular Disease

2.2.1. Considerations with Valvular Patients

  • Antibiotic SBE prophylaxis
  • Anticoagulants
  • Associated Cardiac Abnormalities

2.2.2. Valvular Abnormalities

  • Stenosis - failure to open, "narrowing"
  • Regurgitation or insufficiency - failure to close, "leaking"
  • Combined

2.2.3. Mitral Valve Disease

  • Mitral Stenosis
    • Rheumatic Fever
    • Fibrocalcific Deposits
    • Congenital
    • Autoimmune Diseases (Lupus, etc.)
  • Mitral Regurgitation
    • Rheumatic Fever
    • Cardiac Enlargement
    • Infarction
    • Endocarditis
    • Mitral Valve Prolapse (MVP)
  • Mitral Valve Prolapse
    • Abnormal bowing of valve leaflets (floppy)
    • Common finding on Echocardiography
    • Importance of +/- Regurgitation
  • SBE Prophylaxis
    • MS & MR require prophylaxis
    • MVP without MR - no prophylaxis (unless valve apparatus abnormal)
  • Atrial fibrillation commonly associated with MV disease
    • Often with anticoagulants +/- antiarrythmics

2.2.4. Aortic Valve Disease

  • Aortic Stenosis
    • Rheumatic Fever
    • Senile or Degenerative (Calcific)
    • Congenital (Bicuspid)
  • Aortic Regurgitation
    • Rheumatic Fever
    • Endocarditis
    • Congenital (Bicuspid)
    • Traumatic
    • Aortic Root Disease

SBE prophylaxis is required for both Aortic Stenosis and Aortic Regurgitation.

2.2.5. Prosthetic Heart Valves

  • bioprosthetic
    • Combination of animal (or human) tissues and synthetics
    • No need for anticoagulation
  • Mechanical Prosthetic
    • Synthetic materials alone (usually metal)
    • Always require anticoagulation

All artificial heart valves require SBE prophylaxis.

2.3. Rhythm Disorders (Arrhythmias)

2.3.1. Nomenclature

  • Normal sinus rhythms
  • Tachycardia - rapid heart rate (>100 bpm)
  • Bradycardia - slow heart rate (<60 bpm)
  • Supraventricular - originates above the ventricles (atria)
  • Ventricular - originates within the ventricles, usually life-threatening

2.3.2. Treatment options

  • Medications
    • Antiarrhythmic -- must be discontinued
    • Anticoagulants -- should be discontinued
  • Devices
    • Pacemakers
    • Defibrillators
    • Devices do not require SBW prophylaxis

2.4. Hypertension

2.4.1. Definition

Diastolic (mmHg) Systolic (mmHg)
Mild 90-104 140-159
Moderate 105-115 160-180
Severe > 115 > 180

2.4.2. Demographics

  • 50 million Americans have HTN
  • 1 in 4 adults
  • Only 27% are on adequate therapy
  • 31% of American with HTN don't know they have it
  • HTN kills 42,500 Americans per year, and contributes to 210,000 deaths annually

2.4.3. Modifiable Risk Factor

  • People with uncontrolled HTN are:
    • Three times more likely to develop Coronary Artery Disease
    • Six times more likely to develop Congestive Heart Failure
    • Seven times more likely to suffer a Stroke

2.4.4. Etiology

  • 92-94% is Essential HTN (Ideopathic)
  • 6-8% is Secondary HTN (secondary to another disease)
    • 3-5% due to Renal disease
    • 1% due to Endocrine causes

2.4.5. Treatment

  • Diuretics
  • Beta Blockers
  • Calcium Channel Blockers
  • Angiotension Converting Enzyme Inhibitors
  • Vasodilators
  • Nitrates
  • Sodium Restriction

2.5. Disorders of Myocardial Contraction

2.5.1. Etiologies

  • Cardiomyopathy - intrinsic muscular defect
  • Ischemia
  • Infarction

2.5.2. Cardiomyopathies

  • Hypertrophic - thickened cardiac wall
    • Primary - IHSS or ASH
    • Secondary - Hypertension
  • Dilated - enlarged cardiac chamber volume
    • Primary - Ideopathic
    • Secondary - Infarct, Hypertension, Valvular Dz
  • Medical Considerations
    • Can be very ill, congestive heart failure
    • ? +/- anticoagulants

2.6. Congenital Heart Diseases

2.6.1. Common Disorders

  • Pulmonic and Aortic Stenosis
  • Patent Ductus Areteriosis (PDA)
  • Aortic Coarctation
  • Ventricular Septal Defect (VSD)
  • Atrial Septal Defect (ASD)
  • Transposition of the Great Vessels
  • Tetralogy of Fallot

2.6.2. Associated Illnesses

  • SBE
  • Heart Failure
  • Thrombosis
  • Cyanosis
  • Pulmonary Hypertension

2.6.3. SBE Prophylaxis

  • NOT required for:
    • ASD of the secundum type
    • > 6 months after complete surgical repair
  • Required for:
    • Everyone else

3. SBE Prophylaxis - high rates of Bacteremia with dental procedures

For more detail, see the following article: "Prevention of Bacterial Endocarditis." Recommendations by the American Heart Association. Dajani, AS et. al. [Circulation. 1997;96:358-366.) © 1997 American Heart Association, Inc.].

3.1. Condition Specific Risks

  • High Risk Lesions:
    • Prosthetic valves
    • Cyanotic congenital diseases
    • History of previous SBD
    • PDA
    • Aortic valve disease
    • Mitral regurgitation
    • Mitral stenosis with regurgitation
    • VSD
    • Coarctation
    • Incomplete surgical repair of congenital disease
  • Intermediate Risk:
    • MVP with Mitral Regurgitation or abnormal valve structures
    • Tricuspid valve disease
    • Pulmonary Stenosis
    • Bicuspid Aortic Valve or Degenerative AS
    • Surgically repaired disease < 6 months ago
    • Pure Mitral Stenosis
  • Low or Negligible Risk:
    • MVP with normal valve (No MR)
    • Trivial valvular regurgitation by echocardiogram
    • Isolated ASD
    • Coronary artery disease
    • Pacemaker/Defibrillator
    • Congenital disease, > 6 months after complete repair

3.2. Treatment Regimens

See the following article: "Prevention of Bacterial Endocarditis." Recommendations by the American Heart Association. Dajani, AS et. al. [Circulation. 1997;96:358-366.) © 1997 American Heart Association, Inc.].