Dr. Brian Larocque: Ischemic heart disease and congestive heart failure
A. Atherosclerosis: leads to ischemic heart disease (angina/MI), congestive heart failure, cerebrovascular disease, peripheral vascular disease.
In order to compromise flow through a vessel, at least 50-70% of the vessel lumen needs to be obstructed by atherosclerosis. This decrease in flow leads to ischemia and hypoxia in the tissues. In the heart this leads to angina or MI.
B. Ischemic heart disease (IHD)
1. Anatomy: In the heart there are three main arteries:
Right coronary artery
Left anterior descending artery
Circumflex artery
Typically, the reduction of blood flow is not a problem at rest. It becomes a problem when there is an increase in demand. This sets the stage for angina or an MI.
2. Signs and symptoms of IHD: chest pain (angina)… heavyness in the chest, arm, back, neck angle of jaw, shortness of breath, diaphoresis (sweating). Angina is reversible ischemia of the heart muscle. If full occlusion occurs … the patient will have irreversible ischemia of the heart muscle. This is a myocardial infarction (MI) with death of heart muscle.
3. Treatment of IHD:
a. First treat exacerbating factors: anemia, hyperthyroidism, decrease stress
b. Lifestyle modification: lose weight, exercise, decrease cholesterol in diet
c. Control risk factors: diabetes, hypercholesterolemia, smoking, hypertension
d. Medications:
beta blockers: increase survivability
CCBs:decrease symptoms, not survival
Nitrates (NTG):treat symptoms, do not change survival
Anti-platelets (ASA):increase survival
e. Surgery: angioplasty +/- stent, if vessel is 50-90% occluded … coronary
artery bypass grafting (CABG) with internal mammary artery (resists
reatherosis) or saphenous vein (from leg) which tends to reblock
4. Unstable angina: defined as a changing pattern in angina symptoms. For example an increase in frequency of angina symptoms with the same activity or symptoms coming on with less exertion or at rest. The patient must be asked specifically regarding these concerns. Treatment of unstable angina: ASA, antianginals, anticoagulants (heparin).
5. Classification of angina:
I asymptomatic
IIangina with walking > 2 blocks or 1 flight of stairs
IIIangina with walking < 2 blocks or 1 flight of stairs
IVangina at rest or unstable angina
6. Dental treatment concerns
a. If patient is unstable: refer for emergent care, now.
b. Continue medications, pre-op
c. Avoid exacerbating factors: pain, vasopressors (epinprine), high stress
(therefore, treat early in day, short appointments, etc.)
7. Myocardial infarction (MI):
a. etiology: acute occlusion of coronary artery resulting in muscle death
b. signs and symptoms: more severe and prolonged chest pain. Note in 25% of
MIs the patient will not experience chest pain.
8. Prognosis of MI
a. approximately 50% mortality rate prior to hospitalization
b. <10% mortality rate for in-patients due to arrythmia detection and treatment
c. if the MI kills 40% or greater of the heart, this usually leads to patient death
9. Treatment of MI
a. emergency treatment: CPR, 911, arrythmia treatment including defibrillation
b. thrombolysis: streptokinase, tissue plasminogen activator
c. cardiac catheterization +/- stent, +/- CABG
d. chronic treatment: ACE inhibitor and statin (anticholesterolemic) plus usual
antiangina treatment
beta blocker: decrease risk of reinfarction by 30%
ASA:decrease risk of reinfarction by 30%
ACE inhibitor:decrease risk of reinfarction by 25%
10. Dental treatment considerations:
a. timing of treatment:
0 to 3 months post MI:40 – 50% risk of reMI with 30 – 40% mortality
3 to 6 months post MI:20 – 25% risk of reMI with 30 – 40% mortality
> 6 months post MI:4 – 5% risk of reMI with 30 – 40% mortality
Ok to proceed when: uncomplicated MI, no angina, negative stress test
C. Congestive heart failure (CHF):
1. Definition: failure of the heart of pump enough blood to meet the metabolic demands of the tissues. The normal stroke volume is equal to a ventricular ejection fraction of 50-70%. When ejection fraction falls below 50%, congestive heart failure occurs.
2. Etiology:
a. MI: with loss of muscle and poor wall movement
b. Hypertension: chronic fatigue from working against high blood pressure
c. Others: valve disorders, cardiomyopathy (hereditary, post infection, post
exposure to toxins such as heavy metals or drugs)
3. Types: a. 95% of cases are systolic with weakness of the muscle
b. 5% of cases are diastolic due to non-compliance of the ventricle and an inability to fill
4. Signs and symptoms:
a. left ventricle: shortness of breath, orthopnea, paroxysmal nocturnal dyspnea secondary to backup of fluids in the lungs
b. right ventricle: pedal edema, ascites, end stage: anasarca secondary to backup of fluids in the periphery
5. Prognosis: less than 50% 5 year survival. This improves with some treatment: ACE inhibitors: decrease afterload and preload. Beta blockers can exacerbate symptoms of CHF, but in the long term will prolong life. Digoxin and diuretics: symptom control only, no benefit for survivability.
6. Treatment:
ACE inhibitors
Transplant
Treat underlying conditions
Life style modification
Treat underlying exacerbating factors
7. Dental considerations
a. assess the severity of heart failure:
Ino limitations
IIslight limitations with exertion for example mowing the lawn
IIIShortness of breath (SOB) with ordinary activity
IVSOB at rest
2. Continue medications and avoid exacerbating factors: for example excess
fluids and vasopressors.
3. Avoid supine position in order to avoid orthopnea