The Q-T interval of the electrocardiogram in autopsy proven acute myocarditis in adults

38 Pages·01.256 MB·English

by  Gittleman, I. Wilson

THE Q-T INTERVAL OF THE ELECTROCARDIOGRAM
IN AUTOPSY PROVEN ACUTE’MYOCARDITIS IN ADULTS
A Thesis
Presented to
the Faculty of the School of Medicine
The U niversity of Southern C alifornia
In P artial F ulfillm ent
of the Requirements for the Degree
Master of Science in Medicine
i
"by
I. Wilson Gittleman, M. D#
UMI Number: EP60446
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UMI EP60446
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This thesis, written by
I. W ilson Gittlem an, M.D.
under the guidance of h.A®.. Faculty Committee,
and approved by all its members, has been
presented to and accepted by the Council on
Graduate Study and Research in partial fulfill­
ment of the requirements for the degree of
Master of Science in Medicine
Date.....
Faculty Committee
The author wishes to thank
Bti. G. M. Leiby, ch ief of professional
se rv ic es, and Dis. B. E. Konwaler^ path-
ologist«y. of Birmingham Veterans Admin­
istr a tio n H ospital, and T'. F. B arrett,
ch ief of professional services and L.
Kaplan, pathologist of Wadsworth Veterans
Adm inistration H ospital, for perm ission
to use th eir c lin ic a l and pathologic
records; Dr. G. C. G riffith for h is care­
fu l review of th is work, and esp ecia lly Dr.
M. C. Thorner for his suggestions and
c r itic ism s.
TABLE OF CONTENTS
CHAPTER PAGE
I. INTRODUCTION....................................'. . ....................‘ ............................... 1
II. METHOD...................... h
III. FORMULAE........................................................................................................... 5
IV. RESULTS............................................. 8
V. COMMENT ..................................................................................................... 11
VI. DISCUSSION...................................................................................................... 12
VII. SUMMARY........................................................................................................... IS
BIBLIOGRAPHY . . . . ^ ..................................... 17
APPENDIX.............................................................................................................................. 20
LIST OF TABLES
TABLE PAGE
I, Summary of Formulae used in this work and Their Upper
Limit at N o rm al............................................................. 20
II. Data on Cases from Local Hospitals .................................. 21
III. Data on Cases From L iterature ............................ 23
IV. Comparison of Constants in Cases from Local Hospitals
and Cases from the Literature ................... 2k
V. Comparison of Constants in Rheumatic Cases and Non-
Rheumatic C a s e s ...................................................................... 2$
VI. Comparison of the Cases in Which 22 and QT^ were in
ag reem en t....................... 26
VII- Relation of 22 and QT* in Cases in Which There v/as no
TQ A
ag reem en t................................ 27
V III. Re-Calculation of the Cases of Taran's in which the
constant fe ll below norm al............................................... 28
IX. D istribution of Cases from Local Hospitals (D etails on
Table II) ..................................... 29
X. D istribution of Cases from the Literature (D etails
on Table I I I ) ....................... . . ...................................... 30
C arditis is the most frequent m anifestation of
rheumatic fever and is most often insidious and subclini­
c a l.^ Believing th at laboratory aids in the diagnosis
of rheumatic fever currently used have been disappointing
in determining when the rheumatic inflammatory process has
22 23
begun or has ceased, Taran * studied the duration of
electrical systole (Q-T interval) both absolute and rela­
tive to diastole of fifty children with acute rheumatic
card itis and fifty children during a long period of quies­
cence following acute rheumatic fever. He concluded that
the duration of electrical systole both absolute and rela­
tiv e to diastole is significantly prolonged in a ll cases of
acute card itis. The prolongation was found to be a function
of the severity of the card itis and not of the cardiac rate.
The m ajority of physiologic studies indicate that
disturbance in time relationship of systole and diastole
is a m anifestation of impaired function of the myocardium*
26
Wiggers and Clough found that the period of systole is
of longer duration in functional cardiac disorders. They
further stated th at when more blood returns to the ventricle,
i t responds by expelling more blood not only by & greater
number of ejection periods, but also by a greater relativ e
duration of each systole. Concerning th is mechanism,
13
Lombard and Cope stated that the duration of systole
is influenced so largely by the quantity of venous blood
2
supplied to the heart that th is factor may disguise the
effect produced by the condition of the heart muscle.
12
Katz believes the duration of systole in the diseased
heart as compared with the normal heart would give a method
of determining the functional integrity of the myocardium.
Fridericia^® concluded that in man an abnormal increase in
the duration of systole was indicative of myocardial weak­
ness.
There is considerable variation of opinions, how­
ever, among clinicians and physiologists regarding the
clin ical importance of the measurement of the duration of
electrical systole (Q-T in terv al). Ashman and HudA
stated that measurement of electrical systole may give
valuable inform ation regarding the degree to which the
myocardium is being affected in diphtheria and in acute
6
rheumatic card itis. Cheer reported th at electrical
systole is greatly increased in heart failu re irrespective
of etiology, and probably that an increased electrical
systole may indicate a disturbance in cardiodynamics which
might w ell be formed before clin ical evidence is available.
g
In a la te r study Cheer and Dieuaide found that relative
prolongation of the Q-T interval in cardiac insufficiency
seems to be of nyo cardial origin. Again they found that
in cardiac failure resulting from various causes, e lec tri­
cal systole was abnormally prolonged. However, they
stated that no direct relation exists between the degree of
heart failure and the value of K,* but relative prolongation
of Q-T is present in earliest recognizable cases of myo­
cardial insufficiency* Furthermore, they stated that electro­
cardiographic abnorm alities such as prolonged conduction time
and ventricular preponderance did not obviously affect the
value of K, nor was any correlation between K and the size
15
of the heart seen* Robb and Turman believe that the
Q-T duration seems to be directly related to metabolism,
21 23
presumably cardiac cellu lar metabolism. Taran, 9 as
noted above, stated that the Q-T interval, both absolute
and relativ e to diastole, is significantly prolonged in a ll
cases of card itis, and that th is prolongation is a function
of the severity of the disease and not of the cardiac ratfc.
25
On the other hand, White and Mudd reported the
Q-T interval of apparently little or no clin ical value.
They found no prolongation in patients with structural
cardiac defects. In functional cardiac disturbances, they
found a prolonged Q-T interval only in paroxysmal tachy-
cardiac or disorders causing a marked widening of the QRS
complex.
The above-mentioned physiologic and clin ical evi­
dence presented th e problem of ascertaining the corrected
*K refers in th eir paper to the constant derived
from B azettis11 formula, Q-T - K R-B.
4
Q-T intervals in adults -who dies of acute m yocarditis; also
the problem of comparing the findings of cases with acute
rheumatic m yocarditis with cases of acute nonrheumatic myo­
carditis* To ascertain th is inform ation for diagnostic and
prognostic purposes, the following study was made*
METHOD
A survey was made of a ll the cases over twenty-one
years of age with autopsy diagnoses of acute myocarditis
from 1941-194B at Birmingham and Wadsworth Veterans Admi­
n istratio n Hospitals and the Los Angeles County Hospital*
Only those cases were accepted which presented microspopic
evidence of extensive m yocarditis; which had not received
d ig ita lis for four weeks prior to the time electrocardiogram s
were taken; and which had electrocardiogram s technically
satisfactory for measurement* Fifty-one cases of acute
uyocarditis were collected, fourteen cases of which were
rheumatic, the remainder were non-rheumatic*
As additional evidence, though it is admitted that
it is less satisfactory, the literature was carefully
examined for a ll autopsied cases of acute Jiryocarflitis
with electrocardiograms presented* The above criteria
were again used* Twenty-eight such cases were collected,