Chelates, calcium and digitalis

Progress Edited by EMANUEL

Notes in Cardiology GOLDBENER,

M.D., v.A.(:.c.

I

nvestigators and research workers are invited to submit, with a view to publication in an early issue, r&urn& of work in progress or recently completed.

Chelates, Calcium and Digitalis

T

HERE

IS a group

with

special

The

name

word

chelate

for

claw.

of chemical compounds called chelates.

is derived A

chelate

formed between a metallic molecule

having

irritability,

properties,

two

pable of simultaneously

from

the Greek

of potassium

is

compound

the cell membrane.

a

combining

groups

with the metal between

the

to penetrate

and re-enter

the cell. disappears.

the total

venous

responded

serum calcium,

plete disappearance

and is excreted

of the quantity

and

preparation.

of Naz-EDTA,

the

this group,

stores of the subject

lated calcium. Doctors Milton Kabakow studied acting

and the ability

effect

digitalis

Brothers Hospital,

of Na2-EDTA

toxicity.

by a marked

effect

upon

the che-

patients

All

and New

Bernard

but

had

depletion, of, or com-

one

of these nine patients

of Naz-EDTA All

but

on maintenance

lack of response, clinical

pa-

doses of a digitalis

arrhythmia.

were

potassium,

the subsequent

York)

of

had no one

of

digitalis.

in this group,

the clinical histories,

to and

courses with postmortem

findings in some suggested

in counter-

Twenty-six

similar

intravenous

the

myocarwho

potassium

In the remaining

these

intracardiac

altered

diminution

digi-

of all signs of myocardial

the infusion

of the

The .I.

(Montefiore the

to replace

receiving

of these,

tients were on maintenance

hy-

is a function

of administration,

calcium

of the effective

of administration

pocalcemia route

in the urine as an

of

of long standing

hyperexcitability.

inactive calcium-chelate. The duration and extent rapidity

histories

allow

this occurs,

20 demonstrated Eleven

excitability.

by lower-

the cell membrane

of 26 patients suggestive

arrhythmias dial

its effect on

the concentra-

When

Naz-EDTA,

that the metal ion is no longer available for its For example, the chelate, diusual reactions. ethylenediaminetetraacetate sodium (NazEDTA) is able to bind and lower available

other

level may therefore

talis toxicity Of

pincers of the organic molecule. The chelate structure has such high stability

the

at the cell membrane

more potassium

The chelate resembles

to form a ring structure.

a claw with the metal ion clutched

Lowering

ing the serum calcium

ca-

on

on the active re-entry

into the cell, through

tion of calcium

ion and an inorganic

neighboring

Calcium,

occurs.

hand, exerts an influence

that the arrhythmia

had its origin in some cause other than potassium

patients

depletion. Five patients, three of whom maintenance doses of a digitalis

received infusions of 4 grams of Naz-EDTA (obtained from Riker Labs, Inc., Los Angeles, California) in 250 cc of 5 per cent glucose and With this techwater over a four-hour period. nic, they obtained an average depression of

demonstrated marked wave inversions. The

serum calcium of 1.9 mg %. The Naz-EDTA apparently

the

dence of myocardial disease and was not receiving digitalis. The T waves and/or S-T

following way: Digitalis causes a loss of intracellular potassium. When this is marked, with increased myocardial digitalis toxicity,

segments of the three patients on maintenance digitalis reverted to or toward the iso-electric line under the influence of Na2-EDTA. The

works

in

286

THE

AMICRICAN

were taking preparation,

S-T depressions and T last patient had no evi-

JOIJRNAI.

OI;

CARDIOLOGY

Progress depressed

segments

of the other

who had never been chamber

on digitalis

enlargement

were unaffected electrocardiogram was unaffected

or coronary

by Naz-EDTA. of

the

Notes

two patients,

senting

but who had

bility,

insufficiency,

role of potassium

The

normal

of the ectopic

patient

abolition

noncardiac

evidence may

during

by Na2-EDTA.

and

Kabakow

concluded

work that the induction

of a transient

cemia in patients receiving

digitalis

Did you know that . It is preferable titularly

valuable II,

and

myocardial in (1)

depletion

rhythm;

which time

‘(3)

the

in the production

(2) the safe, temporary dangerous

replenishment

be accomplished the

hyperexcitaevaluating

evaluation

arrhythmia, of potassium

by the oral route; of contour

observed

in the electrocardiograms

receiving

digitalis.

changes

of patients

. .

This is par-

eliciting

The reason

the patient

lies, the pos-

abnormal

Q

surface of the heart However, in the sitting

the heart swings forward

19%

pre-

and aVF.

or diaphragmatic

FEBRIJARY,

and/or

for

tends to face the back. position,

hypocal-

III,

for this is that when terior

this

to take an electrocardiogram

of an adult in the sitting position. waves in leads

from

of

be of value

of a potentially

stores may Brothers

287

in Cardiology

and more of

this surface now faces the left leg.

This allows

more of its potentials

in lead aVF

to be recorded

and in leads II and III. * In a case of cardiac

* arrest,

* pounding

chest wall with the fist may sometimes heart

to beat again.

on the

cause the