2. Contains
Conduction system of heart
Definition
Incidence of cardiac arrhythmias
Causes
Types
Clinical features
Investigation
Cardiac arrhythmias in athletes , football players
3. Introduction
THE term "cardiac arrhythmia" indicates that an
irregularity of heart-beat is present. Many
states of disordered heart-beat, however, are
associated with an entirely regular rhythm, for
example paroxysmal atrial tachycardia [1]
4. Conduction system of heart
The conducting system of the heart
consists of cardiac muscle cells and
conducting fibers (not nervous tissue)
that are specialized for initiating impulses
and conducting them rapidly through the
heart . They initiate the normal cardiac
cycle and coordinate the contractions of
cardiac chambers. Both atria contract
together, as do the ventricles, but atrial
contraction occurs first.
5. Normal Conduction Pathway
The normal impulse spreads from the sinoatrial node
through the atrial muscle at about 1,000 mm. per second
and produces the P wave of the electrocardiogram. Most of
the P-R interval is taken up by the impulse spreading
through the atrio-ventricular node, a structure with a long
refractory period, incapable of rapid conduction (22 mm.
per second). Once in the branches of the bundle of His and
Purkinje fibres the passage of the impulse is rapid (4,000
mm. per second). Contraction occurs as the impulse enters
the ventricular muscle and is followed by the resting state
.[1]
6.
7. Aetiology of Cardiac Arrhythmias
Any abnormal state affecting the myocardium and any process interfering with the
normal action of the valves of the heart may be responsible for an arrhythmia
In addition, many metabolic disturbances may present in this way, and in this
connection the Na+ and K+ interchange across the myocardial cell membrane, Ca+
+ and Mg+ -t + concentration are all of great importance.
Both atrial fibrillation and atrial flutter may occur in the absence of any recognisable
heart disease.
10. Atrial Fibrillation
This may occur as
1. As a paroxysmal rhythm
2. As an established rhythm.
It occurs most frequently in association with
• rheumatic heart disease
• Coronary artery disease
• Systemic hypertension
• Congenital heart disease [least common ]
• Pericardial disease is a numerically small but functionally important precipitating
cause of atrial fibrillation
11. Atrial Flutter
Like atrial fibrillation atrial flutter may occur in two forms, paroxysmal or
established.
It is far less common than atrial fibrillation
Atrial flutter is usually found in association with rheumatic heart disease, coronary
artery disease, thyrotoxicosis and systemic hypertension and is less frequently
encountered than atrial fibrillation in hearts that are otherwise normal. Atrial septal
defect, especially postoperative, is the commonest associated congenital heart
disease
12. Ventricular Tachycardia
This is uncommon
Although almost always associated with organic heart disease it infrequently does
occur in the absence of any recognised disease
The arrhythmia is rapid and the heart beat almost, but not quite reguilar. Cannon
waves may be seen in the neck.
13. Sinus arrhythmia
This is phasic alteration in heart rate in relation
of breathing . The HR increases in inspiration
and decreases in expiration
Significance – this is most common arrhythmia
it is normal phenomenon and is manifestation
of normal autonomic nervous activity .
14. Incidence and Risk Factors Associated With Cardiac Arrhythmias
During Rehabilitation After Coronary Artery Bypass Surgery
The incidence of significant arrhythmias in patients performing a program of cardiac
rehabilitation after CABG and to identify relevant prognostic factors.
cardiac arrhythmias represent a frequent and potentially serious problem in
patients undergoing an inpatient CRP after CABG surgery.
This finding suggests that the incidence of undetected arrhythmias in ambulatory
patients after CABG is high during the first month after surgery
15. Reduced Incidence of Cardiac Arrhythmias in Walkers and
Runners
no significant risk increase for self-reported cardiac arrhythmias associated with
running distance, exercise intensity, or marathon participation. Rhythm
abnormalities were based on self-report, precluding definitive categorization of the
nature of the rhythm disturbance.
However, even if the runners arrhythmias include sinus bradycardia due to running
itself, there was no increase in arrhythmias with greater running distance.
16. Arrhythmias and Adaptations of the Cardiac Conduction System in
Former National Football League Players
While several studies have associated long‐term participation in endurance‐type sports
with an increased risk of atrial fibrillation (AF), this is the first study associating
participation in strength‐type sports with AF.
The majority of former NFL athletes with AF were previously undiagnosed, rate
controlled, and asymptomatic, but 80% met indications for anticoagulation, highlighting
the need for a high level of clinical suspicion for occult AF in this group.
Sinus bradycardia and first‐degree atrioventricular block are typically benign findings in
former athletes, but more severe conduction abnormalities requiring cardiac pacing
also appear more prevalent in this population.