Abstracts 125

Experiences with a Lens Mitral Valve Prosthesis,

I~REDI~RIC~; S. CROSS, M.D.. F.A.c.c. and RICHARD D.

Jo\I:s. PI~.I).. Cleveland, Ohio.

Although the ball-valve prostheses available at the

present time are functioning satisfactorily in thou-

sands of patients, there is still need for the continued

improvement of artificial heart valves. The prc-sent

report describes a valve consisting of a fenticular

closure within a titanium cage which offers several

significant advantages. ‘l’he fens requires a shorter

excursion than does a ball of equivalent diameter;

thus the valve may be made shorter (about half the

height of the ball cage). The reduced bulk of the cage

permits insertion of fens prostheses with larger orifice

size than is possible with the ball design. The silicone

rubbrr lenticufar closure, reinforced with a thin

titanium ring, weighs only a fourth to a third as much

as a ball of comparable diameter. The reduced mass

of a lens compared with a ball decreases inertial

effects during the opening and closing phases of valve

function. Further dynamic advantage has been

achieved by adjusting the density of the lens to ap-

proximately the specific gravity of blood.

Pressure gradients measured across the lenticufar

valve are not different than those for a ball valve of

equal orifice size at flow rates of up to 40 L./min. of

water. Simultaneous left atria1 and left ventricular

pressure tracings in cineangiography demonstrate ex-

cellent function of the valve in vivo. There is less

chance for aortic outflow obstruction with the lens

mitral valve, and less chance for ventricular arrhyth-

mias. The valve has been functioning in patients and

experimental animals for periods up to two years.

Follow-up studies are available on over 100 patients,

and the results of these studies will be presented.

The Permanent Transvenous Electrode-Catheter

Pacemaker for Treatment of Heart Block, SIMON

DACK. M.D.? F.A.c.c., ROBERTS. LITWAK, M.D., F.A.C.C.

and HOWARD GADBOYS, M.D., F.A.c.c., New York,

N. Y.

This paper presents our results of long term pacing

of the heart by a transvenous bipolar electrode-

catheter wedged into the apex of the right ventricle

via the left cephalic or subclavian vein and connected

to a generator implanted subcutaneously in the left

pectoral area through the same incision. This simple

operation performed under local anesthesia and under

fluoroscopic control obviates the necessity of a thora- cotomy for sewing the electrodes into the left epicardial

surface. Fifty-five cases of heart block treated by this method

of permanent endocardial pacing in the period from

October 1965 to October 1966 are compared with 91

VOLUME 19, TANUARY 1967

cases treated by rhoracotomy and epicardial pacing

during the fleriod Prom September 1962 to October

1965. Our early and long term folfo\v-up rcsufts with

the new method indicarc that prroperativ? fjrepara-

tion is simpler and >horter and temf’orary rransvc-

nous pacing prr’op,eratiVely is usually not rrquired i operative and early mortality is louver (2.4 vs. 8.8’zj;),

and postoperative complications are greatly reduced.

Furthermore. the incidence of flacemaker failure

due to electrode or wire breakage or generator failurr.

which was quite high with the epicardial pacrmaket

(427, in 1.5 yr.? 75Th in 3 yr.), has been much fo\ver

with the endocardiaf pacemaker (1473; in 1 yr.).

Modification of the technic of implanting and fixing

the electrode-catheter has lowered this incidence

even further so that only occasionally does the catheter

tip have to be repositioned because of faulty pacing.

This method is now recommended routinely for the

treatment of patients with chronic heart block com-

plicated by Stokes-Adams syndrome, heart failure, or

severe bradycardia.

Surgical Correction of a Taussig-Bing Malforma-

tion: Report of 3 Cases, GEORGE R. DAICOFF. M.D.

and JOHN W. KIRKLIN. M.D., F.A.c.c.. Rochester.

Minn.

Three patients underwent intracardiac repair of the

congenital cardiac anomaly in which the aorta arose

from the right ventricle and the pulmonary artery

straddled a ventricular septal defect, thereby facing

both the right and left ventricles. This malformation is

commonly known as the Taussig-Bing heart. The

purpose of this report is to emphasize the unique sur-

gical implications of this condition and to indicate a

method of successful repair. The clinical features,

cardiac catheterization data and angiocardiograms

will be discussed.

The essential features of the operation were as

follows: (1) patch closure of the ventricular septaf

defect to complete the transposition of the pulmonary

artery to the left ventricle, (2) intraatrial venous

transposition as described by Mustard. and (3) repair

of associated defects. Two of the 3 patients survived

operation, were no longer cyanotic, gained height and

weight, enjoyed increased exercise tolerance and re-

mained free of fluid retention. The third patient

failed to survive because of the complications of

markedly increased pulmonary vascular resistance.

The Antihypertensive Properties of an Imidazoline

Compound (ST 1X), MICHAEL DAVIDO~, M.D.,

NIKOS KAKAVIATOS, M.D. and FRANK A. FINNERTY.

JR., M.D., F.A.c.c., Washington. D. C.

The antihypertensive properties of ST-155 [2-(2,6-

dichlorophenylamine)-2-imidazofine hydrochloride J

126 Abstracts

have been evaluated in 62 patients with severe hyper-

tension. Oral administration of 300 pg. to 32 patients

produced an average reduction in mean arterial pres-

surefroml81 Z!Z 14 to 128 i 19 mm. Hg (29 & 10%).

The average onset, peak and duration of action were

observed in one, two and six hours, respectively. At

the time of peak action there was a 35 +Z 12yc average

increase in cardiac output and 42 f 157, average

decrease in the total peripheral resis:ance (8 patients) ; the average urinary output and sodium and potassium

excretion were decreased by 84 & 32, 83 f 29

and 12 & 5%, respectively (6 patients). Inulin and

PAH clearances were decreased (5 to 10%) at the

end of the first hour and returned to control level

at the end of the second hour (6 patients). Thirty patients received ST 155 as the sole anti-

hypertensive medica ion for an average duration of

16 * 5 weeks. The average daily dose was 42 =I= 32

pg./kg. admisistered i.1 four dirided doses. The mean

arterial pressure fell from an average of 161 + 21 to

an average of 123 Z!X 19 mm. Hg (23 =t 12%) as com-

pared to an average of 143 •I= 14 mm. Hg (10 & 10%)

during prior therapy with thiazides plus reserpine

and alpha-methyldopa and/or guanethidine and/or

hydralazine. All patients gained weight (6 =t 4 lbs);

congestive heart failure developed in 3. Administra-

tion of thiazides promptly produced a further fall in

arterial pressure and weight loss and allowed reduc-

tion in dosage of ST 155.

ST 155 is a rapidly acting, potent and nontoxic

antihypertensive agent effective by mouth which,

when combined with thiazides, would seem to be a

valuable addition to the available antihypertensive

drugs.

Prevention of Lethal Cardiogenic Shock in Dogs

Tolerant to Endotoxin, RONALD H. DIETZMAN, M.D.,

SAM W. MOVSAS, M.D., JOHN A. FEEMSTER, M.D. and

RICHARD C. LILLEHEI, M.D., F.A.c.c., Minneapolis,

Minn.

Diffuse myocardial infarctions were produced in 53

control dogs by closed chest intracoronary artery microsphere embolization. Twenty-two dogs experi-

enced shock (42%), 17 ventricular fibrillation (32oj,),

and 14 did not go into shock (26%). The mean con- trol blood pressure (BP) in the shocked dogs was 138

mm. Hg, the mean cardiac output (CO) was 152 ml./kg./min., and the mean total peripheral resis-

tance (TPR) was 5,543 dynes sec. cm.-5. After

microsphere embolization, the BP fell co 58 mm. Hg

(-58oj,), CO to 43 ml./kg./min. (-72%), and TPR rose to 8,358 dynes sec. cm.? (i-151%). Within 60 minutes of embolization, the BP stabilized at 115 mm. Hg, CO at 81 ml./kg./min. and TPR at

8,358 dynes sec. cm.pa. Only 6 of the shocked dogs (27%) survived longer than 72 hours. Ten other dogs

were made tolerant to 2 mg./kg. of intravenous E.

coli endotoxin by graded injections over six weeks.

Endotoxin in this dosage increases sympathetic nerve

activity and catecholamine secretion. Microsphere

embolization in these tolerant dogs failed to produce

shock, even though infarction occurred and all 10

dogs (lOO’%j survived longer than 72 hours. The pre-

embolization BP in tolerant dogs was 155 mm. Hg,

CO 220 ml./kg./min., and TPR 3,320 dynes sec.

cm. ph. After microsphere embolization, the BP fell to

141 mm. Hg (-I’%), CO to 163 ml./kg./min.

(-26’%), and TPR rose to 4,169 dynes sec. cm.m5

(i-125’%). At 60 minutes postembolization, the BP

stabilized at 159 mm. Hg, CO at 152 ml./kg./min.

and TPR at 5,075 dynes sec. cm.?. These values for

BP and CO of tolerant dogs were significantly higher

than those of the control dogs (p = 0.0002), and the TPR significantly lower (p = 0.02). Thus endotoxin

tolerance appears to prevent cardiogenic shock in dogs

by reducing the peripheral vasoconstrictive response

associated with the infarction.

Transmission of Electrocardiograms from a Com-

munity Hospital for Remote Computer Analysis,

ROBERT J. DOBROW, M.D., ARNOLD FIELDMAN, M.D.,

W. PAGE C. CLASON, M.D., RALPH F. REINFRANK,

M.D. and CESAR A. CACERES, M.D., Hartford, Conn.

and Washington, D. C.

Recent advances in the automated measurement

and analysis of electrocardiograms, as developed by

the Instrumentation Field Station of the U. S. Public

Health Service, were suggested as a model and have

been successfully applied in Hartford Hospital. The

purpose of this project was to demonstrate the feasi-

bility of the system within the setting of a large com-

munity hospital. This has been accomplished by

establishing communications link by DATA-phone,

mail and teletype between Hartford Hospital and a

remote computer center in Washington, D. C. Addi-

tional objectives have been to: (1) evaluate the effects of phone transmission on the electrocardio-

gram; (2) evaluate the accuracy of computer diag-

noses and their usefulness in the interpretation of electrocardiograms in the community hospital; and

(3) introduce computer-assisted electrocardiographic diagnosis for emergency room patients.

Forty-three hundred electrocardiograms have been

transmitted by DATA-phone for remote computer

analysis; 300 were taken on emergency room patients;

4,000, on ambulatory patients in our clinics. Computer reports on clinic patients were mailed to the hospital; those on emergency room patients were teletyped.

THE AMERICAN JOURNAL OF CARDIOLOGY