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FUNNY LOOKING BEATS

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									FUNNY LOOKING BEATS

     CHAPTER 7
        ESCAPE BEATS
• ONE OR MORE EXTRA CARDIAC CYCLES
  ARE THE MOST COMMON ABNORMALITY
  IN AN EKG.
• CONDUCTION CELLS OUTSIDE THE SA
  NODE DEVELOP AN ABNORMALLY
  INCREASED AUTOMATICITY.
• THE SA NODE IS UNABLE TO SUPPRESS
  THE INCREASED AUTOMATICITY BY
  NORMAL OVERDRIVE SUPPRESSION.
THE MOST AUTOMATIC CELL GENERATES A STIMULUS
WHICH CAUSES A CONTRACTION, AND THE CELL BECOMES
AN ABNORMAL PACEMAKER.

INCREASED AUTOMATICITY IS CONSIDERED CARDIAC
IRRITIBILITY BECAUSE IT IS UNDESIRABLE.

THE EXTRA BEATS ARE UNDESIRABLE BECAUSE THEY MAY
NEGATIVELY AFFECT CARDIAC OUTPUT.

SA NODE SUPPRESSION CAUSING CARDIAC RATE SLOWING
IS ANOTHER CAUSE FOR EXTRA BEATS.

OVERDRIVE SUPPRESSION WEAKENS OR FAILS BECAUSE THE
SA NODE IS NO LONGER THE MOST AUTOMATIC SITE IN THE
CONDUCTION SYSTEM.
THE AUTOMATICITY SITE IN THE CONDUCTION SYSTEM
MAY COMPETE TO OVERDRIVE THE FAILING SA NODE
AND CAUSE A CONDUCTED IMPULSE.

AN ECTOPIC FOCUS IS A SITE OF IMPULSE FORMATION
LOCATED SOMEWHERE OTHER THAN THE SA NODE.

ECTOPIC BEATS OR ECTOPY ARE EXTRA CONTRACTIONS
IDENTIFIED BY THE LOCATION OF THEIR FOCI.

ADDITIONAL NOMENCLATURE INDICATES THE PHYSICAL
SITE OF THE FOCUS, DEFINING THE CONTRACTION AS
ATRIAL, JUNCTIONAL, OR VENTRICULAR.
       PREMATURE ECTOPY

• ECTOPIC BEATS ARE CATAGORIZED BY
  THEIR TIMING IN THE EKG.
• PREMATURE BEATS OCCUR IN THE EKG
  BEFORE THE NEXT REGULAR BEAT CAN
  OCCUR.
• EXAMPLES: PAC, PJC, PVC
• IDENTIFIABLE BY THEIR WAVES OF
  CONDUCTION RECORDED ON THE EKG.
      ESCAPE ECTOPY
• MAJOR FORM OF ECTOPY IS THE
  CONTRACTION WHICH OCCURS
  BECAUSE THE UNDERLYING RATE IS
  ABNORMALLY SLOW.
• THESE CONTRACTIONS ARE A
  COMPENSATORY MECHANISM OF
  THE HEART FOR
  BRADYDYSRHYTHMIA.
THE SINUS RHYTHM IS DEPRESSED WITH A RATE
SLOWER THAN 60 BEATS.

NORMAL AUTOMATICITY OF THE OTHER CONDUCTION
CELLS COMPETES WITH THE OVERDRIVE SUPPRESSION
OF THE SLOWED SINUS RHYTHM.

ALLOWS AN ECTOPIC FOCUS TO ESCAPE TO CAUSE A
CONTRACTION.

ANY ECTOPICS IN BRADYCARDIC RHYTHM ARE
CLASSIFIED AS ESCAPE BEATS.

ESCAPE ECTOPY IS COMPENSATORY MECHANISM FOR A
SLOW RATE. PREMATURE ECTOPY INDICATES CARDIAC
IRRITIBILITY.
MANAGEMENT OF THE PATIENT MUST CONSIDER THE
UNDERLYING PATHOLOGY.

ESCAPE ECTOPY IS MANAGED BY ADDRESSING THE
BRADYCARDIA.

PREMATURE ECTOPY IS MANAGED DIRECTLY WITH
ANTIDYSRHYMIC THERAPIES.
              PAC’S
• PACEMAKER STIMULUS.
• STIMULUS ARISES SOMEWHERE OTHER
  THAN THE SA NODE WITHIN THE TWO
  ATRIA.
• ANY PREMATURE COMPLEX WITH A P
  WAVE WITHIN NORMAL LIMITS IS A PAC.
• IF IT FAILS TO MEET THE CRITERIA IT IS
  CLASSIFIED AS ABERRANT PAC.
ATRIAL ECTOPY IS COMMON.

IT DOES NOT RULE OUT THE PRESENCE OF
SIGNIFICANT HEART DISEASE.

MAY CONTRIBUTE TO TACHYDYSRHYTHMIA.

PATIENTS WITH PAC’S FREQUENTLY REPORT A
SENSATION OF PALPITATIONS OR HAVING
“SKIPPED A BEAT”.
            PJC’S

• PACEMAKER STIMULUS ARISES FROM
  AN ECTOPIC FOCUS WITHIN THE
  JUNCTION.
• P WAVE CAN BE ABSENT, INVERTED,
  RETROGRADE.
• JUNCTIONAL CONTRACTIONS ARE MORE
  OMINIOUS AND SUGGEST UNDERLYING
  PATHOLOGY.
              PVC’S
• ECTOPIC FOCUS WITHIN THE
  VENTRICLES.
• MOST OMINOUS OF ALL ECTOPIC
  BEATS.
• INDICATE INCREASED IRRITIBILITY.
• MAY BE TREATED WITH
  ANTIDYSRHYMIC MEDICATIONS.
  ABERRANT COMPLEXES
• ONE VENTRICLE REPOLARIZES AT A
  SLOWER RATE THAN THE OTHER.
• ONE VENTRICLE IS THEN ABLE TO
  ACCEPT AN ELECTRICAL IMPULSE
  CAUSING DEPOLARIZATION EARLIER
  THAN THE OTHER VENTRICLE.
• INDIVIDUAL COMPLEXES THAT APPEAR
  DIFFERENT THAN THE COMPLEXES OF
  THE UNDERLYING RHYTHM.
THE ABERRANT COMPLEXES BECAUSE THEY DO NOT
FOLLOW THE SAME ELECTRICAL CONDUCTION
PATHWAY.

ABERRANTLY CONDUCTED COMPLEXES INCLUDE AN
ABERRANTLY CONDUCTED COMPLEX THAT HAS A
NEGATIVE QRS WHEN THE UNDERLYING RHYTHM HAS
A POSITIVE QRS COMPLEX.

THE QRS OF THE ABERRANTLY CONDUCTED COMPLEX
IS WIDER OR SHORTER THAN THE COMPLEXES OF
THE UNDERLYING RHYTHM.
ABERRANTLY CONDUCTED COMPLEXES CAN
ORIGINATE FROM ANYWHERE IN THE ATRIA,
AV JUNCTION, OR VENTRICLES.

THE ORIGIN WILL DETERMINE THE SIZE AND SHAPE.

USUALLY OCCUR AS INDIVIDUAL COMPLEXES, NOT
ENTIRE RHYTHMS.
  PULSELESS ELECTRICAL
        ACTIVITY
• DYSRHYTHMIA WITHOUT
  CONTRACTION OF THE
  MYOCARDIUM.
• DEPOLARIZATION SEEMS TO OCCUR
  BUT NO PULSE OR B/P.
• LETHAL AND TREATMENT MUST
  BEGIN IMMEDIATELY.
MAY BE CAUSED BY HYPOVOLEMIA, HYPOXIA, CARDIAC
TAMPONADE OR TENSION PNEUMOTHORAX.

PEA MAY OCCUR IF THE MYOCARDIUM IS SO DAMAGED
IT CANNOT CONTRACT, ALTHOUGH ELECTRICAL
IMPULSES ARE BEING CONDUCTED BY THE
ELECTRICAL CONDUCTION PATHWAYS.
TEMPORARY PACEMAKERS
• USED TO MAINTAIN HEART
  RATE IN AN EMERGENCY
  SITUATION OR UNTIL A
  PERMANENT PACEMAKER
  CAN BE SURGICALLY
  IMPLANTED.
• TWO TYPES OF TEMPORARY
  PACEMAKERS.
TRANSVENOUS (THROUGH A VEIN).

THE LEADWIRE IS INSERTED THROUGH THE SKIN AND
THREADED THROUGH A LARGE VEIN INTO THE RIGHT SIDE
OF THE HEART.

ELECTRICAL IMPULSES STIMULATE THE ATRIUM AND THE
IMPULSES ARE CARRIED THROUGH THE CARDIAC
ELECTRICAL CONDUCTION SYSTEM, CAUSING
DEPOLARIZATION.

TRANSDERMAL OR TRANSCUTANEOUS (THROUGH THE
SKIN).

TWO LARGE PADS AS ELECTRODES CONDUCT THE IMPULSE.
TWO LEADWIRES EACH CONNECTED TO A PAD.

ONE PAD ON THE FRONT AND ONE PAD ON THE BACK.

THE IMPULSES ARE THEN CONDUCTED THROUGH THE
BODY AND HEART STIMULATING THE ENTIRE HEART
CAUSING DEPOLARIZATION.

TRANSDERMAL IS EASILY POSITIONED AND DOES NOT
REQUIRE PIERCING THE PATIENT’S SKIN TO POSITION THE
ELECTRODES.

FIXED PACEMAKER – GENERATES A CONSTANT RATE, 72 TO
80 IMPULSES.
DEMAND – SET TO GENERATE IMPULSES ONLY WHEN THE
PATIENT’S RATE FALLS BELOW A PREDETERMINED RATE.
PERMANENT PACEMAKERS
• NECESSARY WHEN THE PATIENT IS
  UNABLE TO MAINTAIN A NORMAL HEART
  RATE OR CARDIAC OUTPUT, EVEN WITH
  AID OF MEDICATIONS.
• GENERATOR IS SURGICALLY IMPLANTED
  UNDER THE PATIENT’S SKIN.
• USUALLY UNDER THE UPPER LEFT CHEST
  SKIN OR ABDOMINAL AREA.
    ATRIAL PACEMAKER
• LEADWIRE AND ELECTRODE ARE
  INSERTED INTO THE RIGHT ATRIUM.
• THE IMPULSE STIMULATES THE ATRIA,
  THEN FOLLOWS THE NORMAL
  ELECTRICAL PATHWAY.
• THE DISCHARGE IS REPRESENTED BY A
  VERTICAL LINE CALLED A PACER SPIKE.
• THE SPIKE IS USUALLY FOLLOWED BY A P
  WAVE AND QRS.
THE P WAVE MAY NOT BE SEEN UNLESS THE
ELECTRODE IS POSITIONED HIGH IN THE RIGHT ATRIUM.

THE P WAVE FOLLOWING A PACER SPIKE IS USUALLY
NOT MEASURED.

ATRIAL PACEMAKER CAN ONLY BE USED IF THE AV
JUNCTION AND VENTRICULAR CONDUCTION
PATHWAYS ARE FUNCTIONING.

RARELY USED TODAY BECAUSE THEY ARE LESS
EFFICIENT THAN VENTRICULAR OR SEQUENTIAL
PACEMAKERS.
         VENTRICULAR
         PACEMAKERS
• THE LEADWIRE AND ELECTRODE ARE
  PLACED IN THE RIGHT VENTRICLE.
• CAUSES DEPOLARIZATION OF THE
  VENTRICULAR MUSCLE.
• THE ATRIA MAY NOT DEPOLARIZE IF THE
  ATRIAL MYOCARDIUM IS EXTENSIVELY
  DAMAGED.
• A PACER SPIKE FOLLOWS THE QRS.
• THE QRS IS USUALLY GREATER THAN
  0.12 SECONDS.
SEQUENTIAL PACEMAKERS
• COMMONLY USED.
• STIMULATES THE DEPOLARIZATION
  OF BOTH THE ATRIA AND
  VENTRICLES.
• THE LEADWIRE HAS TWO
  ELECTRODES – ONE IN THE ATRIA
  AND ONE IN THE VENTRICLE.
THE RHYTHM STRIP USUALLY SHOWS TWO PACER
SPIKES BEFORE EACH QRS COMPLEX.

SPIKES MAY OCCUR CLOSELY TOGETHER THAT THEY
APPEAR AS ONE LONG SPIKE.

FIRST SPIKE REPRESENTS THE ATRIA FIRING, THE
SECOND REPRESENTS THE VENTRICLE FIRING.

P WAVE MAY BE SEEN, AND QRS IS GREATER THAN
0.12 SECONDS.
   CAPTURE AND PACING
• THE PERCENTAGE OF CAPTURE
  AND PACING MUST BE
  DETERMINED.
• CAPTURE REFERS TO THE
  CARDIAC MUSCLE’S ABILITY TO
  CONDUCT THE ELECTRICAL
  IMPULSE GENERATED BY A
  MECHANICAL PACEMAKER.
• P WAVE OR QRS COMPLEX
  FOLLOWING EVERY PACER SPIKE.
THE PRESENCE OF A COMPLEX FOLLOWING A PACER
SPIKE DOES NOT ALWAYS INDICATE THE
CONTRACTION OF THE MYOCARDIUM, ONLY THE
CONDUCTION OF AN ELECTRICAL IMPULSE.

THE PATIENT MUST BE ASSESSED.

PERCENTAGE OF CAPTURE IS DETERMINED BY THE
NUMBER OF PACER SPIKES FOLLOWED BY A COMPLEX
IN RELATIONSHIP TO THE TOTAL NUMBER OF
PACER SPIKES ON THE ENTIRE STRIP.

LOSS OF CAPTURE – A QRS DOES NOT FOLLOW A
PACER SPIKE.
LOSS OF CAPTURE INDICATES THE ELECTRICAL
IMPULSE GENERATED BY THE MECHANICAL PACEMAKER
HAS NOT BEEN CONDUCTED.

MAY INDICATE THE MYOCARDIUM IS SO DAMAGED, IT
IS UNABLE TO RESPOND TO EVERY ELECTRICAL
IMPULSE.

PACING REFERS TO THE PERCENTAGE OF COMPLEXES
GENERATED BY THE MECHANICAL PACEMAKER.

THE PERCENTAGE OF PACING DEPENDS ON THE
PACEMAKER ABILITY OF THE PATIENT’S OWN HEART

THE PERCENTAGE OF CAPTURE SHOULD ALWAYS BE
100%.
            AICD’S
• AUTOMATIC IMPLANTABLE
  CARDIOVERTER DEFIBRILLATORS
• CAN IDENTIFY AND TREAT SOME RAPID
  LETHAL DYSRHYTHMIAS.
• SURGICALLY IMPLANTED.
• CAN BE PROGRAMMED TO INITIATE LOW-
  VOLTAGE ELECTRICAL IMPULSES WHEN
  THE HEART RATE BECOMES VERY FAST.
THE AICD IMPULSE ATTEMPTS TO FORCE THE HEART
INTO A NORMAL RATE.

IF THE HEART RATE CONTINUES TO INCREASE, OR IF
THE RHYTHM BECOMES V-FIB OR V-TACH, THE AICD
WILL DELIVER A SHOCK STRONG ENOUGH TO
DEFIBRILLATE.

THE AICD WILL DEFIBRILLATE THE PATIENT UNTIL
THE HEART HAS RECOVERED OR UNTIL IT IS TURNED
OFF BY MEDICAL PERSONNEL.

ON THE RHYTHM STRIP, THE FIRING OF THE AICD
APPEARS SIMILAR TO A PACING SPIKE, BUT MAY HAVE
A GREATER AMPLITUDE.

								
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