From abalos@scf.usc.edu Mon Dec 8 18:09:40 1997 Date: Mon, 8 Dec 1997 15:47:52 -0800 (PST) From: abalos To: jmiles@hsc.usc.edu Subject: Paroxysmal Tachycardia PAROXYSMAL TACHYCARDIA (ATRIAL AND VENTRICULAR)

Paroxysmal Tachycardia (Atrial and Ventricular)

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A.  In paroxysmal tachycardia, repeated periods of very fast heartbeats
begin and end suddenly.

B.  For atrial paroxysmal tachycardia, the narrow QRS tachycardias
involve an abnormal pathway, either within the A_V node (intranodal) or
beside it (paranodal).  The abnormal fast pathway may not show the
decremental conduction properties charateristic of the "slow" pathway --
the A-V node.  Under critical circumstances (in the presence of
premature ectopic beats, or at a particular heart rate or level of
autonomic tone), a tachycarsia may be established using these
parthways.  The most common situation (>95%) is a slow-fast tachycardia
(using the A-V node for the antegrade conduction and the abnormal
pathway for retrograde conduction), in which P(prime) waves occur nearly
simultaneous with, and are obscured by, the QRS complex.  The much rarer
fast-slow A-V nodal reentry tachycardia produces P(prime) waves before
the next QRS (RPprime > PprimeR);  this arrythmia may be present in an
incessant form.
 Tachycardia usually is paroxysmal with sudden onset, often initiated by
a premature atrial ectopic beat with a critical PR interval.  The
tachycardia rate typically is 160 to 200 beats per minute, and symptoms
of palpitation are universal but variably tolerated.
 Ventricular tachycardia is characterized by rapid heart beats due to
electrical signals arising from the ventricles, rather than the atrium.
Ventricular ectopic beats may or may not cause symptoms or be of
prognostic significance.  When found in the absence of cardiovascular
disease, they have no prognostic significance, but when found
post-infarction, in heart failure, and in aortic stenosis, they carry
prognostic implications related to their frequency.  VEB's may merit
management when they cause symptoms.  To date, there is no evidence that
their treatment improves prognosis (in any disease association).

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Sample Problems: 





Sample Problem:  Differentiate the difference between the origins of
atrial and ventricular tachycardia.

Sample Problem 2:  Differentiate the QRS complexes of supraventricular
tachycardia to that of ventricular tachycardia.

Sample Problem 3: In one sentence, describe what paroxysmal tachycardia
is.

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Answers:





Sample Problem Answer:  Atrial tachycardia originates from an electrical
impulses from the atrium, while ventricular tachycardia originates from
electrical impulses from the ventricle.

Sample Problem Answer 2:  In supraventricular tachycardia, the QRS
complexs are often normal, because ventricularactivation proceeds over the
normal pathways.

Sample Problem Answer 3:  In paroxysmal tachycardia, repeated periods of
very fast heartbeats begin and end suddenly.

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For more information on this topic, please refer to Berne & Levy , pages 46-47

Also, check out the following links that may be helpful:

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Or, Jump to Lesson Number:


respiratory
1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | Exam #1
auditory
17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | Exam #2
cardiovascular
28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | Exam #3

No!
Please don't make me go to any of those pages!
I want to go somewhere completely different!

This page was written by Marjorie I. Abalos , a student in this course.

BME 403 Pages maintained by the T.A., Douglas Miles.