SINUS

1
SINUS ATRIAL DYSRHYTHMIAS

• CHAPTER 3

2
SINUS RHYTHMS

• SA NODE REFERRED TO AS THE PACEMAKER OF THE
  HEART.
• NORMALLY INITIATES ELECTRICAL IMPULSE.
• IF THE SA NODE FAILS TO GENERATE AN IMPULSE, ANY
  OTHER PACEMAKER CELL WITHIN THE ATRIA IS CAPABLE
  OF INITIATING AN IMPULSE.
• INHERENT HEART RATE OF THE ATRIA IS 60 TO 100
  ELETRICAL IMPULSES PER MINUTE.

3
UPRIGHT P WAVES (DEPOLARIZATION) PR INTERVAL 0.12
TO 0.20 SECONDS QRS COMPLEX LESS THAN 0.12
SECONDS P WAVES AND THE LENGTH OF PR INTERVALS
MAY VARY. RHYTHMS ORIGINATING FROM SA NODE ARE
SINUS RHYTHMS OR SINUS DYSRHYTHMIAS DYSRHYTHMIA
IS USED WITH ALL CARDIAC RHYTHMS EXCEPT NORMAL
SINUS RHYTHM.
4
SINUS DYSRHYTHMIAS ARE USUALLY NOT
SERIOUS. PATIENT ASSESSMENT IS ESSENTIAL TO
DETERMINE THEIR TOLERANCE OF THE
DYSRHYTHMIA. PATIENT IS SYMPTOMATIC (MEDICALLY
UNSTABLE) IF ANY OCCUR CHEST PAIN, WEAKNESS,
FAINTNESS, SUDDEN CHANGE IN BLOOD PRESSURE,
CONFUSION, OR UNRESPONSIVENESS.
5
NORMAL SINUS RHYTHM

• ONLY RHYTHM CONSIDERED NORMAL.
• BOTH ATRIA AND VENTRICLES DEPOLARIZE AT REGULAR
  INTERVALS.
• P TO P AND R TO R INTERVALS ARE REGULAR.
• P TO P INTERVALS ARE THE SAME LENGTH AS THE R TO
  R INTERVALS.
• P WAVE 0.12 TO 0.20 SECONDS
• QRS INTERVAL ltO.12 SECONDS
• 60 TO 100 IMPULSES PER MINUTE.

6
Normal Sinus Rhythm (NSR)
7
SINUS BRADYCARDIA

• FOLLOW THE NORMAL CONDUCTION PATHWAY, HOWEVER THE
  RATE IS ltTHAN 60 IMPULSES PER MINUTE.
• CAN BE NORMAL FOR SLEEPING INDIVIDUALS AND
  ATHLETES.
• IF THE RATES FALLS SIGNIFICANTLY OR THE PATIENT
  BECOMES SYMPTOMATIC- DANGEROUS
• CAUSES VOMITING, DIGITALIS, MORPHINE, OR
  SEDATIVES

8
Notice the rate of this strip. 40bpm In sinus
bradycardia the rate must be under 60bpm. All
complexes are normal in appearance.
9
SINUS TACHYCARDIA

• RATE BETWEEN 101 TO 150 IMPULSES PER MINUTE.
• FOLLOWS NORMAL CONDUCTION PATHWAY.
• AS RATE INCREASES- P WAVES MAY BECOME HIDDEN IN
  THE T WAVE OF THE PRECEDING QRS COMPLEX.
• MAY BECOME SERIOUS IF THE PATIENT BECOMES
  SYMPTOMATIC.

10
The impulse is initiated at the SA node. This
rate is 120 bpm. Sinus tach falls within 101
150bpm.
11
COMMON CAUSES PAIN FEVER ACUTE
ANEMIA HEMORRHAGE EXERCISE DRUGS SUCH
AS ATROPINE NICOTINE CAFFEINE AMPHETAMINES
12
SINUS ARRHYTHMIA

• SA NODE INITIATES ALL ELECTRICAL IMPULSES, BUT AT
  IRREGULAR INTERVALS.
• P TO P AND R TO R INTERVALS CHANGE WITH
  RESPIRATIONS, PRODUCING AN IRREGULAR RHYTHM.
• ALL COMPLEXES ARE WITHIN NORMAL RANGES PLUS ALL
  TIMES ARE WITHING NORMAL RANGES.
• PATIENT HEART RATE INCREASES WHEN THE PATIENT
  INHALES AND THE HEART RATE DECREASES WHEN THEY
  EXHALE.
• 6 SECOND STRIP IS MORE RELIABLE TO DETERMINE THE
  RATE.
• P TO P AND R TO R INTERVALS ARE IRREGULAR

13
THE LONGEST R TO R INTERVAL WILL BE LESS THAN
TWICE THE LENGTH OF ANY OF THE REMAINING R TO R
INTERVALS. SIGN OF DISEASED SA NODE OR
CORONARY ARTERY DISEASE IN ADULTS. NORMAL IN
INFANTS OR YOUNG CHILDREN. USUALLY NOT SERIOUS
UNLESS CARDIAC OUTPUT DECREASES AND THE PATIENT
BECOMES SYMPTOMATIC.
14
P to P and R to R intervals are
irregular. Longest R to R will be less than twice
the length of any of the remaining R to R
intervals. Change due to a change in respirations.
15
SINUS EXIT BLOCK AND SINUS ARREST

• SINUS BLOCK OCCURS WHEN THE SA NODE INITIATES AN
  ELECTRICAL IMPULSE THAT IS BLOCKED AND NOT
  CONDUCTED TO THE ATRIA.
• ATRIA DO NOT DEPOLARIZE, AND A P WAVE IS NOT
  SEEN.
• SINUS ARREST OCCURS WHEN THE SA NODE DOES NOT
  INITIATE AN ELECTRICAL IMPULSE.
• THE ATRIA DO NOT DEPOLARIZE AND A P WAVE WILL NOT
  BE SEEN.

16
pause
In a sinus exit block the pause is equal to
exactly two or more cardiac cycles of the
underlying rhythm. The electrical impulse from
the SA node is blocked and not conducted to the
atria.
17
BOTH DYSRHYTHMIAS APPEAR SIMILAR ON THE MONITOR,
P WAVES ARE ABSENT AND QRS COMPLEXES ARE NOT
SEEN. THIS FORMS A PAUSE ON THE MONITOR OR
STRIP. THE LENGTH OF THE PAUSE MAY DETERMINE IF
THE DYSRHYTHMIA IS AN EXIT BLOCK OR SINUS ARREST.
18
THE PAUSE OF A SINUS EXIT BLOCK IS EQUAL
TO EXACTLY TWO OR MORE CARDIAC CYCLES. THE SA
NODE CONTINUES TO FIRE AT ITS NORMAL RATE SO THE
RHYTHM WILL USUALLY BE REGULAR EXCEPT WHERE THE
PAUSE OCCURS. DURING SINUS ARREST THE PAUSE IS
NOT EQUAL TO 2 OR MORE CARDIAC CYCLES. THE SA
NODE IS NOT FIRING, ANY PACEMAKER CELL IN THE
HEART CAN BEGIN ELECTRICAL IMPULSES.
19
THE COMPLEX THAT ENDS THE SINUS ARREST MAY BE
ATRIAL, JUNCTIONAL, OR VENTRICULAR. MAY BE
CAUSED BY THE FOLLOWING MYOCARDIAL
INFARCTION HYPOXIA DIGITALIS OR
QUINIDINE PATIENT ASSESSMENT IS ESSENTIAL
TO DETERMINE THE PATIENTS TOLERANCE.
20
The pause is not equal to exactly two or
more cardiac cycles of the underlying rhythm.
21
ATRIAL DYSRHYTHMIAS

• IF THE SA NODE FAILS, ANY OTHER PACEMAKER SITE
  WITHIN THE ATRIA IS CAPABLE OF INITIATING AN
  IMPULSE.
• CARDIAC RHYTHMS ORIGINATING FROM ATRIAL SITES ARE
  ATRIAL DYSRHYTHMIAS.
• THE IMPULSE TRAVELS THROUGH THE AV NODE, BUNDLE
  OF HIS, BUNDLE BRANCHES TO THE PURKINJE FIBERS.
• USUALLY NOT LETHAL

22
PREMATURE ATRIAL CONTRACTION

• PAC IS AN INDIVIDUAL COMPLEX THAT OCCURS EARLIER
  THAN THE NEXT EXPECTED COMPLEX OF THE UNDERLYING
  RHYTHM.
• ORIGINATES FROM ANY ATRIAL SITE OUTSIDE THE SA
  NODE.
• USUALLY OCCUR IN AN UNDERLYING SINUS RHYTHM,
  WHICH MAY BE REGULAR EXCEPT FOR THE PAC.

23
Can you find the PAC in this strip?
24
THE P WAVE MAY APPEAR DIFFERENT IN SIZE OR
SHAPE THAN THE P WAVES OF THE UNDERLYING
RHYTHM, MAY BE HIDDEN IN THE T WAVE OF THE
PREVIOUS COMPLEX. THE PAC IS FOLLOWED BY A PAUSE
BEFORE THE UNDERLYING RHYTHM RETURNS. TWO TYPES
OF PAUSES NONCOMPENSATORY OR COMPENSATORY. TO
DETERMINE MEASURE THE R TO R INTERVALS BEFORE AND
AFTER THE PAC.
25
PAC
PAC
Not a true dysrhythmia but an individual complex
26
NONCOMPENSATORY PAUSE

• MEASURE FROM THE R WAVE OF THE COMPLEX BEFORE THE
  PAC TO THE R WAVE OF THE COMPLEX AFTER THE PAC.
• WILL BE LESS THAN TWO TIMES THE R TO R INTERVAL
  OF THE UNDERLYING RHYTHM.
• MAY ALSO BE CALLED AN INCOMPLETE COMPENSATORY
  PAUSE.

27
COMPENSATORY PAUSE

• MEASURE FROM THE R WAVE OF THE COMPLEX BEFORE THE
  PAC TO THE R WAVE OF THE COMPLEX AFTER THE PAC.
• WILL BE TWO TIMES THE R TO R INTERVAL OF THE
  UNDERLYING RHYTHM.
• MAY BE CALLED A COMPLETE COMPENSATORY PAUSE.

28
PAC IS USUALLY FOLLOWED BY A NONCOMPENSATORY
PAUSE. THE UNDERLYING RHYTHM MUST BE
IDENTIFIED WHEN INTERPRETING RHYTHMS WITH A
PAC. EASIER TO IDENTIFY IN A SINUS RHYTHM OR A
RHYTHM WITH A BRADYCARDIC RATE. DETERMINING RATE
INCLUDE THE R WAVE OF THE PAC IN THE TOTAL
COUNT OF R WAVES.
29
A PAC REPRESENTS INCREASED IRRITABILITY OF
THE ATRIA. INDICATES THAT CARDIAC CELLS ARE ABLE
TO RESPOND TO EVEN MILD ELECTRICAL STIMULATION
AND MAY DEPOLARIZE IN AN UNPREDICTABLE RATE OR
MANNER. A PAC BY ITSELF IS NOT SERIOUS. THEY ARE
MONITORED BECAUSE THEY CAN LEAD TO A MORE
SERIOUS PAROXYSMAL ATRIAL TACHCARDIA. PAC IS
NOT A TRUE ATRIAL DYSRHYTHMIA, IT IS
AN INDIVIDUAL COMPLEX.
30
CAUSES PAIN FEAR ANXIETY SUDDEN
EXCITEMENT EXERCISE DIGITALIS ATROPINE NICOTINE CA
FFEINE AMPHETAMINES
31
PAROXYSMAL ATRIAL TACHYCARDIA

• SUDDEN ONSET OF TACHYCARDIA WITH A RATE OF gt THAN
  151.
• FREQUENTLY TRIGGERED BY A PAC.
• P WAVES MAY BE HIDDEN IN THE T WAVES.
• VENTRICLES DO NOT HAVE TIME TO FILL COMPLETELY
  BEFORE EACH CONTRACTION.

32
Paroxysmal atrial tachycardia is the sudden
onset of tachycardia greater than 151 bpm.
Usually triggered by a PAC.
33
THE RAPID HEARBEAT OF A PAT MAY DECREASE THE
AMOUNT OF OXYGENATED BLOOD CIRCULATED TO THE
MYOCARDIUM. THE PATIENT MAY COMPLAIN OF
WEAKNESS, DIZZINESS, PALPITATIONS, OR THE HEART
IS DOING FLIP-FLOPS. PAT MAY STOP AS SUDDENLY
AS IT STARTS.
34
NOT A LETHAL DYSRHYTHMIA BUT SHOULD BE MONITORED
CLOSELY. THE BEGINNING OF THE PAT MUST BE SEEN
AND THE UNDERLYING RHYTHM THAT PRECEDES THE PAT
MUST BE IDENTIFIED. IF THE ONSET IS NOT SEEN,
THE DYSRHYTHMIA IS CALLED SUPRAVENTRICULAR
TACHYCARDIA (SVT).
35
SUPRAVENTRICULAR TACHYCARDIA

• TERM USED WHEN THE DYSRHYTHMIA FITS ALL THE
  CHARACTERISTICS OF A PAT BUT THE BEGINNING OF THE
  DYSRHYTHMIA IS NOT SEEN.
• ORIGINATES FROM AN IRRITABLE SITE ABOVE THE
  BUNDLE OF HIS WITH A RATE GREATER THAN 151.

36
Is this strip SVT?
37
WANDERING ATRIAL PACEMAKER

• ORIGINATES FROM AT LEAST THREE DIFFERENT SITES
  ABOVE THE BUNDLE OF HIS.
• SIZE AND SHAPE OF EACH INDIVIDUAL COMPLEX IS
  DETERMINED BY THE SITE OF ORIGIN FOR THAT
  COMPLEX.
• IF FROM THE ATRIA, A P WAVE OCCURS FOLLOWED BY A
  QRS COMPLEX.

38
IF FROM THE AV JUNCTIONAL AREA, THE P WAVES MAY
BE INVERTED, HIDDEN, OR MAY FOLLOW THE QRS
COMPLEX. P WAVES MAY NOT BE SEEN BEFORE EVERY
QRS COMPLEX, AND PRI MAY VARY OR BE ABSENT. P TO
P AND R TO R INTERVALS VARY, PRODUCING
AN IRREGULAR RHYTHM. MAY BE CAUSED BY HEART
DISEASE, M.I., OR DRUG TOXICITY. USUALLY NOT
LETHAL BUT IS TREATED BECAUSE OF THE
IRRITIBILITY OF THE HEART MUSCLE.
39
Occurs from at least three different sites above
the Bundle of His. May include any pacemaker site
in the atria, including the SA node, AV node or
any combination of these areas.
40
ATRIAL FLUTTER

• A SINGLE IRRITIBLE SITE IN THE ATRIA INITIATES
  MANY ELECTRICAL IMPULSES AT A RAPID RATE.
• NORMAL P WAVES ARE NOT PRODUCED.
• FLUTTER WAVES (F WAVES) ARE FORMED.
• SAW-TOOTHED OR JAGGED APPEARANCE ON THE STRIP.

41
THE NEGATIVE (DOWNWARD) STROKE OF THE F WAVE
REPRESENTS ATRIAL DEPOLARIZATION. THE POSITIVE
(UPWARD) STROKE OF THE F WAVE INDICATES ATRIAL
REPOLARIZATION. USUALLY DEPOLARIZE MORE RAPIDLY
THAN NORMAL. ALL COMPLEXES ARE USUALLY WITHING
NORMAL RANGES EXCEPT THE F WAVES WHICH RANGE
FROM 250 TO 350 IMPULSES PER MINUTE.
42
ATRIAL FLUTTER WITH A VENTRICULAR RATE OF LESS
THAN 60 IMPULSES PER MINUTE IT IS CALLED ATRIAL
FLUTTER WITH A SLOW VENTRICULAR
RESPONSE. VENTRICULAR RATE OF 100 TO 150
IMPULSES PER MINUTE IT IS CALLED ATRIAL FLUTTER
WITH A RAPID VENTRICULAR RESPONSE. THE RATIO OF
FLUTTER WAVES TO EACH QRS COMPLEX DESCRIBES THE
DYSRHYTHMIA.
43
TWO FLUTTER WAVES WITH ONE QRS COMPLEX 21
BLOCK FOUR F WAVES WITH ONE QRS COMPLEX 41
BLOCK IF THE NUMBER OF FLUTTER WAVES IS THE SAME
BEFORE EVERY QRS COMPLEX THE RHYTHM IS
REGULAR. WITH VARIED F WAVES THE RHYTHM IS CALLED
ATRIAL FLUTTER WITH VARIABLE VENTRICULAR RESPONSE.
44
Notice the saw-toothed waves. What combination
of flutter waves would this represent?
45
ATRIAL FIBRILLATION

• (A FIB) IS AN INCREASED IRRITABILITY OF ALL THE
  CARDIAC CELLS IN THE ATRIA.
• MANY SITES WITHIN THE ATRIA ATTEMPT TO INITIATE
  ELECTRICAL IMPULSES.
• SINCE SO MANY IMPULSES ARE INITIATED, MOST OF THE
  IMPULSES ARE NOT CONDUCTED.

46
THE ATRIA IS NOT COMPLETELY DEPOLARIZED. THE
ATRIAL MUSCLE DOES NOT FORCEFULLY CONTRACT. ONLY
A QUIVERING MOVEMENT OCCURS (FIBRILLATORY WAVES).
APPEAR AS A WAVY LINE BETWEEN EACH QRS
COMPLEX NO TRUE P WAVES OR PR INTERVALS
EXIST. ATRIAL HEART RATE OF 350 TO 500. THE
VENTRICULAR RATE IS USUALLY WITHIN NORMAL LIMITS
OF 60 TO 100 IMPULSES. CALLED CONTROLLED
ATRIAL FIBRILLATION.
47

• ATRIAL FIBRILLATION WITH A SLOW VENTRICULAR
• RESPONSE - ltTHAN 60 PER MINUTE
• ATRIAL FIBRILLATION WITH RAPID VENTRICULAR
• RESPONSE 101 TO 150 PER MINUTE
• ATRIAL FIBRILLATION WITH A VENTRICULAR RATE
• GREATER THAN 150 IMPULSES PER MINUTE IS CALLED
• UNCONTROLLED ATRIAL FIBRILLATION.
• TREATMENT DEPENDS ON THE PATIENTS TOLERANCE
• OF THE DYSRHYTHMIA AND THE SYMPTOMS.

48
See any P waves?
49
SYMPTOMATIC SIGNS PALE OR CYANOTIC COOL, CLAMMY
SKIN SHORTNESS OF BREATH WEAKNESS OR
DIZZINESS CHEST PAIN UNRESPONSIVENESS SYMPTOMS
VARY DEPENDING ON THE CAUSE OF THE A FIB, THE
VENTRICULAR RESPONSE, CARDIAC OUTPUT, AND THE
TOLERANCE BY THE PATIENT.