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
Clint is a 19 year old male that’s brought to the emergency department for acute chest pain. Upon examination, you notice that his heart rate is really fast, about 170 beats per minute. He has a history of depression, and is currently being treated with TCAs. He is otherwise healthy. A few minutes after arriving, Clint loses consciousness. His ECG shows this.
All right, so based on his presentation and ECG, Clint has some form of arrhythmia. The best way to approach arrhythmias is to one: know what a normal ECG looks like, and two: have a good classification system to narrow down the diagnosis. To help identify an irregular rhythm, you can look at the morphology of the waveform and make sure that there is a P wave before every QRS complex, and a QRS complex after every P wave.
Now let’s take a look at the heart rate. The resting heart beats at a rate between 60 to 100 times per minute, and each of those beats starts off with depolarization of the sinoatrial node, and so we call it a normal sinus rhythm. It's also important to know that there is typically a delay in the conduction at the AV node and the Bundle of His, which gives some time for ventricular filling before the ventricle contracts. On the ECG, this is represented by the PR interval, which should be less than 5 small boxes, or 200 milliseconds.
Now, any disturbance in the rate, rhythm, site of origin, or conduction of the cardiac electrical activity is called an arrhythmia. Arrhythmias could be completely asymptomatic, and be picked up incidentally on an ECG. Arrhythmias can also present with palpitations, which is a sensation of your heart beating too hard or fast, fluttering, or skipping a beat. Additionally, they may alter cardiac output, causing individuals to present with signs of hypotension and decreased brain perfusion, like dizziness, altered mental status, or syncope.
An arrhythmia is any disturbance in the rate, rhythm, site of origin, or conduction of the cardiac electrical impulse. Ventricular arrhythmias are those that originate within the ventricles and have a wide QRS complex on ECG. These two types of ventricular arrhythmias are ventricular tachycardia and ventricular fibrillation.
Ventricular tachycardia can be monomorphic meaning that all the QRS complexes look the same, or polymorphic meaning the QRS complexes are different in each beat. A specific and very dangerous type of polymorphic ventricular tachycardia is Torsades de Pointes, which presents a twisting pattern of QRS complexes. This can rapidly progress to ventricular fibrillation, in which the whole PQRST ECG pattern breaks down completely, leaving just some random undulating waves. This is the most common cause of sudden cardiac death.
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