Hello, welcome everybody, this is doctor Bolad, board certified physician in cardiology,
interventional cardiology and internal medicine, certified by the American Board of Internal
Medicine. If you are new to this channel, then definitely consider hitting the subscribe button
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subscribers, thank you for your continued support. Today I will talk to you about fast heart rate,
medically known as TACHYCARDIA. In normal conditions, the heart beats at a rate of
60 to 100 beats per minute. The heartbeat originates in the upper right chamber of
the heart from the SINOATRIAL NODE, travels down the atrium to the ATRIOVENTRICULAR NODE
and then travels to the ventricles. This pattern of beating is known as SINUS RHYTHM. When the
heart rate exceeds 100 beats per minute, we label the individual as suffering from
TACHYCARDIA. There are three broad categories of tachycardia.
The first category is SINUS TACHYCARDIA and this occurs when the heart is beating
in the normal pattern I just described, but the heart rate is increased to above 100 beats per
minute. In the vast majority of patients, sinus tachycardia does not directly cause symptoms,
although a patient with a greater awareness of his or her heartbeat may report palpitations, which is
the subjective awareness of a rapid or forceful heartbeat. In the great majority of patients,
Sinus tachycardia occurs as a physiologic response to a demand for greater cardiac output,
increased sympathomimetic state, or parasympathetic withdrawal. Causes include fever,
volume depletion, infection, anemia, anxiety, overactive thyroid, heart failure, lung disease,
caffeine and nicotine intake and abrupt withdrawal of certain medications like beta blockers.
Sinus tachycardia also occurs in POSTURAL ORTHOSTATIC TACHYCARDIA SYNDROME, generally
abbreviated as POTS . This is a condition that occurs predominantly in young women
in the absence of structural heart disease. Patients develop symptoms upon the STANDING,
symptoms such as palpitations, fatigue, lightheadedness, or exercise intolerance.
POTS is defined as an increase in heart rate of more than 30 beats per minute
in the absence of a drop in systolic blood pressure of more than more than 20 mmHg.
Another cause of sinus tachycardia is known as INAPPROPRIATE SINUS TACHYCARDIA
and it is an unusual condition that occurs in individuals without apparent heart disease or
other cause for sinus tachycardia, such as fever or overactive thyroid and is generally considered
a diagnosis of exclusion. Patients are invariably symptomatic, most commonly with palpitations,
but other common symptoms include chest discomfort, fatigue, dizziness, presyncope,
syncope, and shortness of breath The second large category of increased heart rate
is known as SUPRAVENTRICULAR TACHYCARDIA. This is an abnormality of rapid heart rhythm originating
in the upper chambers of the heart, the chambers above the ventricles. These are usually
associated with hemodynamic compromise or severe symptoms due to the tachycardia such as angina,
heart failure or low blood pressure requiring rapid termination of the arrhythmia.
Causes of Supraventricular tachycardia include ATRIOVENTRICULAR NODAL REENTRANT TACHYCARDIA
abbreviated as AVNRT. This is due to dual electrical pathways in or near the
atrioventricular node and occurs more commonly in women compared to men. The dual pathways are
composed of a slow pathway and a fast pathway. Another cause of supraventricular tachycardia
is known as ATRIOVENTRICULAR REENTRANT TACHYCARDIA abbreviated as AVRT. This is caused by development
of an accessory pathway, short circuiting the cardiac conduction system, and this accessory
pathway is not related to the atrioventricular node. Other causes of Supraventricular tachycardia
include FOCAL ATRIAL TACHYCARDIA which is usually paroxysmal and self-limited fast heart rate,
arising from a single site or area of micro-reentry outside of the sinus node,
ATRIAL FLUTTER which occurs due to the development of a macro-reentrant circuit in the upper chambers
of the heart, ATRIAL FIBRILLATION which is fast and IRREGULAR heart beating originating from the
upper part of the heart, and MULTIFOCAL ATRIAL TACHYCARDIA due to organized atrial activity
caused by electrical activity from three or more sites in the upper part of the heart.
The third large category of increased heart rate is known as VENTRICULAR TACHYCARDIA. This is
fast heart rate originating from the lower chambers of the heart, the VENTRICLES. If
the heart rate of this arrhythmia is not very fast, it might be well tolerated. However,
if the speed is very fast, this arrhythmia might be life threatening and can lead to collapse and
cardiac arrest. This is because the lower part of the heart is beating too fast and does not
have enough time to fill with blood to pump and to circulate the blood to the rest of the body.
The seriousness of this tachycardia also depends on whether the heart pumping function
is normal or reduced, with the latter having a more serious impact on the circulation.
Treatment of the tachycardias depends on the CAUSE of the tachycardia. Sinus tachycardias are treated
with correction of the underlying abnormality. Supraventricular tachycardias are generally either
treated with medications to reduce the fast heart rate or treated with cardiac ablation,
in which catheters are introduced to the heart, and the focus of arrhythmia
is ablated or destroyed by the catheter either using heat therapy or cold therapy.
For ventricular tachycardias, treatments depend on the cause of the arrhythmia
and the rate of the arrhythmia, and include medications, cardiac ablation
and implantation of a cardioverter defibrillator. If you have any question about what I presented to
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This is Doctor Bolad, helping you with your heart health, thanks for watching, and talk to you soon.