Download RECENT TRENDS IN TREATMENT OF ARRHYTHMIAS

RECENT TRENDS IN TREATMENT OF
ARRHYTHMIAS
BY
Mohamed Adel Mohamed Zakria (M.B., B. Ch)
ESSAY
Submitted in Partial Fulfillment For Master Degree
IN CARDIOLOGY
Under Supervision of
Professor Dr.
Dr.
Mo homed Lotfi Shahwan
Meshah Taha Hassannin
PROF. OF CARDIOLOGY & HEAD OF
LECTURER IN CAPDIOLOGY
THE DEPARTMENT OF
FACULTY 0 MEDICINE ZAGAZIG
CARDIOLOGY FACULTY OF
UNIVERSITY
MEDICINE ZAGAZIG UNIVERSITY
FACULTY OF MEDICINE
ZAGAZIG UNIVERSITY
1986
SUMMARY
Before discussion of recent ant arrhythmic therapies, it is
important to understand the anatomy and physiology of the
conductive system of the heart, and to study the genesis of
cardiac arrhythmias.
Recent trends in treatment of arrhythmias include.
1. Drug therapy:
Drugs are classified according to the mechanism of action into 4
classes:
Group 1: are drugs of membrane stabilizing effect. It is
subgrouped into:
Group I A: Quinidine is the prototype of this group. Its main
effect is the reduction of maximal rate of depolarization, so it
slows the conduction velocity and increases the effective
refractory period with minor effects on repolarization.
Group I B: Lidocaine, Mexiletine, Tocainide and phenytoin are
the members of this subgroup, they not affect the refractoriness
of cardiac cells.
Group 2; are drugs with beta-adrenergic receptor blocking
effects. In the blocking concentration they only reduce the slope
of pacemaker potential, while in very much higher concentration
they reduce the maximal rate of depolarization of the cardiac
action potential.
Group 3:
Amiodarone and bretylium prolong the duration of the action
potential in ventricular and Purkinje fibres. This lead to
prolongation of ARP.
Group 4:
Calcium
antagonists
slow
the
spontaneous
diastolic
depolarisation in the cardiac muscle.
The most recent antiarrhythmic drugs are included togethier. A
little is known about it electrophysiologic properties, and more
studies are still needed. Some of them e.g. pranolium may be of
help in protection in patients who are at high risk of sudden
coronary death.
II. Non Pharmacologic Treatment.
1. Cardiac pace makers: are electronic devices that delivers
electrical stimuli to the heart to treat bradycardia or tachycardia.
They perform basically
two functions: they stimulate the heart, and most of them can
sense impulses as well.
2. Electrical therapy of cardiac Arrhythmias Electric shock
depolarises all excitable myocardium, interrupts reentrant
circuits, discharges foci, and establishes electrical homogenecity
that terminates reentry. It offers obvious advantage over drug
therapy.
3. Surgical Treatment of Arrhythmias:
The aim. of a surgical approach in supraventricular tachycardia
(SVT) are to excise or isolate the origin of a tachycardia, to
interrupt a reentrant path way necessary for maintainance of the
tachycardia, and to induce AV block in patients with (SVT) that
cause rapid ventricular responses.
In ventricular tachycardias: indirect surgical approaches,
including cardiac thoracic symapathectomy, coronary artery
bypass grafting and ventricular aneur-ismectomy or infarct
resection are successful in about 60% of cases.