00:00 / 00:00
Bundle branch block
Pulseless electrical activity
Atrioventricular nodal reentrant tachycardia (AVNRT)
Premature atrial contraction
Long QT syndrome and Torsade de pointes
Premature ventricular contraction
Rheumatic heart disease
Atrial septal defect
Coarctation of the aorta
Patent ductus arteriosus
Ventricular septal defect
Hypoplastic left heart syndrome
Tetralogy of Fallot
Total anomalous pulmonary venous return
Transposition of the great vessels
Pericarditis and pericardial effusion
Aortic valve disease
Mitral valve disease
Pulmonary valve disease
Tricuspid valve disease
Coronary steal syndrome
Polycystic kidney disease
Renal artery stenosis
Peripheral artery disease
Subclavian steal syndrome
Superior mesenteric artery syndrome
Human herpesvirus 8 (Kaposi sarcoma)
Chronic venous insufficiency
Deep vein thrombosis
Acyanotic congenital heart defects: Pathology review
Aortic dissections and aneurysms: Pathology review
Atherosclerosis and arteriosclerosis: Pathology review
Cardiac and vascular tumors: Pathology review
Cardiomyopathies: Pathology review
Coronary artery disease: Pathology review
Cyanotic congenital heart defects: Pathology review
Dyslipidemias: Pathology review
Endocarditis: Pathology review
Heart blocks: Pathology review
Heart failure: Pathology review
Hypertension: Pathology review
Pericardial disease: Pathology review
Peripheral artery disease: Pathology review
Shock: Pathology review
Supraventricular arrhythmias: Pathology review
Valvular heart disease: Pathology review
Vasculitis: Pathology review
Ventricular arrhythmias: Pathology review
0 / 11 complete
0 / 1 complete
ECG tracing p. 298
torsades de pointes p. 312
Ventricular refers to the bottom chambers of the heart, the right and left ventricles, rather than the top chambers, the right and left atria. Fibrillation means quivering from uncoordinated muscle fiber contraction. So, ventricular fibrillation, sometimes called v-fib or VF, means that the heart’s muscle fibers start quivering because they’re not contracting at the same time.
Normally, an electrical signal spreads fast enough that all the muscle fibers in the ventricles contract at almost the same time, which essentially acts like a single, coordinated contraction. If they don’t all contract at about the same time, not much gets accomplished. It’s kind of like a rowboat; it works best when everyone rows at the same time, right?
Well, with VF, all the rowers stop rowing together, and just row whenever they want; the rowboat just moves in circles, and eventually sinks.
Just like a rowboat, if the heart’s not squeezing anymore, and it’s just squirming around “like a bag of worms” — a common description of what it looks like — then you can probably guess that this situation is extremely dangerous. Because your body, and especially your brain, isn’t getting fresh oxygen, ventricular fibrillation can lead to death within minutes of onset, which is called sudden cardiac death.
Now, the exact mechanisms leading up to VF aren’t always super clear because it’s hard to know what’s happening in the heart immediately before VF. Most often, however, the heart cells become stressed or damaged in such a way that different areas of tissue are structurally and electrically changed, and thus have different properties; this known as tissue heterogeneity. When they’re homogenous, or the same, they all behave in the same ways and can depolarize and contract at nearly the same time.
When the tissues have different electrical properties, they aren’t as good as working together, and are more prone to abnormal behavior and depolarizing on their own. In general, tissue heterogeneity can happen after something stresses the ventricular muscle, such as: certain medications; illicit drugs, like methamphetamine or cocaine; electrolyte imbalances; and ischemia to the ventricular muscle.
Ventricular fibrillation, also called v-fib or just VF, is when there's quivering of ventricular muscle fibers because they're not contracting at the same time. This results in failure to pump oxygenated blood to the brain, which within minutes can lead to sudden cardiac death. Prompt defibrillation and advanced cardiac life support measures need to be initiated to restore normal heart rhythm and prevent mortality.
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