List the common and training-related abnormalities of an athlete's ECG.
- Sinus bradycardia
- 1° AV block
- Incomplete RBBB
- Early repolarization
- Isolated QRS voltage criteria for LV hypertrophy
List the uncommon and training-unrelated abnormalities of an athlete's ECG.
- T wave inversion
- ST segment depression
- Pathological Q waves
- LA enlargement
- L or R axis deviation
- RV hypertrophy
- Ventricular pre-excitation
- Complete LBBB or RBBB
- Long or short QT interval
What is a genetic CV disease? Characteristics?
Diseases in which one's inherited genome is the prime determinant of the presence of serious CV disease
- Often fatal at an early age
- Majority are asymptomatic as they develop
What is homocysteinuria? How does it develop?
- Inherited metabolic disorder w/ SNPs disabling enzymes involved in interconversion/breakdown of sulphur-AAs, methione and cysteine
- Homocysteine builds up in the bloodstream, damaging the arterial endothelial lining --> accelerated atherosclerosis and clotting events
Risks for individuals homozygous for homocysteinuria? Heterozygotes?
- Homo = begin having heart attacks and strokes in their teens and twenties
- Hetero = at increased risk for MI in mid-life (40-60 years old)
What % of sudden cardiac deaths in young athletes does genetic CV disease account for?
What is the most common cause of sudden cardiac death in young athletes during exercise?
What is hypertrophic cardiomyopathy?
Hypertrophy that occurs in the absence of other obvious circulatory or valvular deficiencies such as hypertension and aortic stenosis
In what pattern is hypertrophic cardiomyopathy inherited?
Inherited in an autosomal dominant pattern
What fraction of the US population has hypertrophic cardiomyopathy?
What happens to the integrity of cardiac tissue as a consequence of HCM? Significance?
Increased fibrosis (interweaving of muscle and connective tissue)
- Make cardiac muscle stiff, low compliance, low stretch --> impairs diastolic filling
How does hypertrophy cause an energy imbalance? What can this ultimately lead to?
- Relative decrease in number of capillaries and increase in distance b/t capillaries
- Increased ratio of myofibrils to mitochondria
- Leads to ischemia b/c energy cost goes up, but O2 not increasing proportionally
What characterizes diastolic dysfunction? Symptoms?
- Impaired filling due to abnormal relaxation and increased chamber stiffness
- Increased LA and LV end diastolic pressure
- Sx: pulmonary congestion, exertional dyspnea, syncope
What is asymmetric septal hypertrophy?
Septum is growing into groove that should be LV outflow into aorta --> blood gets backed up
What is the pathology of hypertropic cardiomyopathy?
- Cardiac myocytes are outgrowing blood supply
- Energy cost is sky-rocketing due to both muscle mass & outflow obstruction
- Stiff, fibrotic muscle impairs cardiac filling
What is the most common first symptom of hypertrophic cardiomyopathy?
Describe the cycle of pathologic hypertrophy of HCM.