Cardiovascular Miscellany II Flashcards
Cardiac arrhythmia
disturbance in heart rhythm due to deranged cardiac electrical signaling
Supraventricular tachycardia
Arrhythmia originating from the atrium
Ventricular tachycardia
Arrhythmia due to reentry around the edge of a scar in the left ventricle, especially a patchy myocardial infarction (of IHD) creating numerous small areas of non-conducting tissue for a cardiac impulse to bounce off of until it finds a path to zing around at a high rate of speed. Huge cause of sudden cardiac death.
Ventricular fibrillation
immediately life-threatening arrhythmia of chaotic ventricular activation at a rapid rate with lack of cardiac pumping
Asystole
lack of electrical activity in the heart
Palpitations
“racing heart”
Syncope
loss of adequate CO due to sustained arrhythmia can produce loss of consciousness
Channelopathy
heart disease of arrhythmias due to defective cardiac myocyte ion channels, usually due to genetic mutations
Long QT syndrome
Phase 2 channelopathy of the left ventricle that causes early after-depolarization (EAD)
Brugada syndrome
Autosomal dominant, sodium channelopathy that leads to shortened/failed APs and localized conduction block in the RV which predisposes to phase 2 re-entrant ventricular tachycardia
Catecholeminergic polymorphic ventricular tachycardia
Familial genetic disease caused by mutations in the cardiac ryanodine receptor (Sarcoplasmic Ca2+ release channel) that causes high cytosolic calcium leading to DAD during phase 4 that predisposes to ventricular tachycardia triggered by high levels of catecholamines
Cardiomyopathy
heterogeneous group of myocardial diseases associated with mechanical and/or electrical dysfunction of the heart
Idiopathic dilated cardiomyopathy
wastebasket category of nonspecific end-stage heart disease with cardiac dilatation and heart failure (systolic dysfunction) and no cause evident (90%)
Hypertrophic Cardiomyopathy
group of genetic diseases with hypertrophy as a compensatory mechanism for mutations in genes (beta-myosin heavy chain) encoding contractile proteins of the cardiac sarcomere (diastolic dysfunction)
Restrictive cardiomyopathy
least common cardiomyopathy that leads to diastolic dysfunction (impaired compliance) due to amyloidosis, radiation-induced fibrosis, or idiopathic
Dystrophin
cell membrane protein that connects the intracellular cytoskeleton to the ECM (mutated in X-linked DCM)
Alcoholic cardiomyopathy
cardiomyopathy caused by alcohol intake (alcohol abuse leads to direct toxic effects on the myocardium by alcohol and its metabolites (like acetylaldehyde) + beriberi heart disease from thiamine deficiency
Peripartum cardiomyopathy
mutlifactorial cardiomyopathy that occurs late in gestation or several weeks postpartum due to pregnancy HTN, volume overload, increased cleavage products of prolactin, etc. that can induce myocardial dysfunction
Arrhythmogenic right ventricular cardiomyopathy
autosomal dominant disorder of cardiac muscle (probably second “hit” being viral infection) with variable penetrance manifesting as right sided heart failure and ventricular rhythm disturbances that can cause SCD
Myocarditis
Myocarditis encompasses a diverse group of clinical entities in which infectious agents and/or inflammatory processes primarily target the myocardium
Cardiac myxoma
Most common primary tumor of adult heart: benign gelatinous mesenchymal neoplasm of endocardium
What is the most common cause of rhythm disorders?
ischemic injury (direct damage or due to dilation of heart chambers with consequent alteration of conduction system firing
What is sudden cardiac death (SCD)?
sudden death typically due to sustained ventricular arrhythmias in individuals with underlying heart disease (CAD) who may or may not have been symptomatic in the past
True or false: SCD is often the first manifestation of IHD.
true!
True or false: frank infarction is a prerequisite for SCD.
FALSE- 80-90% of patients show no evidence of myocardial necrosis after resuscitation
What are 5 general pathways that can lead to end-stage DCM?
1) Genetics (dystrophin mutations)
2) Infection
3) Alcohol or toxins (doxorubicin)
4) Peripartum cardiomyopathy
5) Iron overload
What does a DCM heart look like?
enlarged, flabby heart that is dilated in all chambers. Mural thrombi often present
What is the epidemiology of DCM? What are the presenting symptoms? Why?
20-50 y/o. Manifests as slowly progressive CHF (dyspnea, easy fatigability, poor exertional capacity) due to ineffective contraction
What is the normal EF in end-stage DCM?
less than 25% (normal 50-65%)
What is the underlying cause of ARVC?
genetic mutation in desmosomal junctional proteins as intercalated disks (plakoglobin) OR proteins that react with the desmosome
What is the morphology of ARVC?
thin RV wall due to myocyte replacement by fatty infiltrates (some lymphocytes) and lesser amounts of fibrosis until later stage fibrous scarring
What is the difference between the mutations in DCM and HCM?
some of the mutations are in the same proteins, but DCM causes depression in motor function (systolic dysfunction) while HCM causes hypercontractility that will eventually lead to diastolic dysfunction (impaired filling)
What is the gross pathology of HCM?
Thick-walled, heavy, hypercontractile heart (assymetric septal hypertrophy)
What is the most common form of restrictive cardiomyopathy?
endomyocardial fibrosis (disease of children and young adults in Africa due to nutritional deficiencies and/or inflammation due to helminthic infections)
What is the most common cause of myocarditis in the US?
viral infections (coxsackieviruses A and B and enteroviruses)
What are the two ways in which myocarditis causes injury?
1) direct cytolytic injury
2) immune response against the virally infected cells cross-reacts with proteins like the myosin heavy chain
What is the most common systemic disorder associated with pericarditis?
uremia
Primary pericarditis is typically due to what?
viral infection
What is the morphology of acute viral pericarditis?
fibrinous exudate giving pericardial surface an irregular, shaggy appearance (bread and butter)
What is the morphology of acute bacterial pericarditis?
fibrinopurulent exudate often with areas of frank pus
What are the symptoms of pericarditis?
atypical chest pain (worse at rest) and a prominent friction rub that could potentially cause tamponade (and lead to shock)
What constitutes the most common malignancy of the heart?
tumor metastasis- angiosarcomas (especially from lung, lymphoma, breast, etc.)
List the 5 most common primary cardiac tumors.
1) Myxomas
2) Fibromas
3) Lipomas
4) Papillary fibroelastomas
5) Rhabdomyomas
What are the 2 major complications of cardiac transplantation?
1) rejection
2) allograft arteriopathy (late, stenosing intimal proliferation in the coronary arteries leading to ischemic injury due to immunologic response producing local growth factors)
What is a normal QT interval corrected for heart rate, QTc?
</= 440 msec
What are the causes of long QT?
- Ischemic heart disease
- Low K+, Ca+ or Mg+
- Channelopathy
- etc.
Why are long QTs risky?
at increased risk for EAD
What is the risk associated with EAD?
ventricular tachycardia –> SCD
What does a long QT do to the action potential?
increases phase 2 (plateau phase) because you have a problem with you potassium channels (usually delayed repolarization)
What would you suspect to be the underlying cause of a child with syncope or sudden death due to polymorphic ventricular tachycardia?
- Congenital long QT syndrome
- Catecholaminergic polymorphic ventricular tachycardia
What is the underlying cause of LQT1?
Loss of function in repolarizing outward channel IKs
What is the underlying cause of LQT2?
Loss of function in repolarizing outward channel IKr
What is the underlying cause of LQT3?
Loss of inactivation/closure ability in the inward sodium channel (Ina)
What is torsades de pointes?
the type of polymorphic ventricular tachycardia typical of congenital long QT syndromes caused by EADs from multiple sites
What does the ECG of torsades de pointes look like?
a twisted ribbon
What is the epidemology of Brugada syndrome?
mostly recognized in young Asian males. Present at average age of 40 with syncope or sudden cardiac death due to ventricular tachycardia (especially during sleep)
What does the EKG of someone with Brugada syndrome look like at rest?
Persistently elevated ST segments (≥2 mm) descending with an upward convexity to an inverted T wave (classic “coved type” Brugada pattern) in leads V1-V3
What is the life-saving treatment in torsades de pointes and Brugada syndrome and Arrhythmogenic right ventricular cardiomyopathy?
ICD
What is the epidemiology/symptoms of Catecholaminergic polymorphic vnetricular tachycardia?
presents at age of 8 with syncope, SCD due to ventricular tachycardia during emotional or physical stress
What is the mechanism of arrhythmias?
Triggered activity resulting from delayed afterdepolarizations due to high intracellular calcium.
How are cardiomyopathies classified?
on the basis of function and on the basis of structure
What is an epsilon wave? What is the cause of it?
Notch in terminal part of QRS
(most prominent in lead V1) that can be a manifestation of right ventricular cardiomyopathy
Where is the most common site of myxoma?
left atrium (80%)
What are the major clinical manifestations of myxoma?
- valvular “ball valve” obstruction
- Embolization
- Syndrome of constitutional signs/symptoms: fever, malaise (duet o IL-6 from tumor)
Why is myxoma a must-not miss?
it is uniformly curable by surgical resection
How do you diagnose myxoma?
echocardiography
When do you see giant cells with “stellate” structures? What are these called?
Sarcoidosis! These are called “asteroid bodies”
What is the prototype of restrictive cardiomyopathy?
cardiac amyloidosis
Other than viruses, what are two notable causes of myocarditis?
1) Lyme disease
2) Hypersensitivity myocarditis
What are the major complications of myocarditis?
acute heart failure
dilated cardiomyopathy
