ABSTRACTS

SYSTEMIC HYPEROSMOLALITY WITH VIGOROUS GRADED EXERCISE: A DETERMINANT OF HEMODYNAMIC RESPONSE Marco Carbajal, M.D., Albert E. Raizner, M.D., Neil Allen, B.S., Robert A. Chahine, M.D., Robert J. Luchi, M.D., Baylor College of Medicine and VA Hospital, Houston, Texas.

The hemodynamic response to vigorous exercise shows

marked individual variation. Recent work from our labora- tory has indicated that abrupt increases in plasma osmo-

lality (Poem) may result in significant falls in systemic blood pressure by reflex and direct mechanisms. To test the possibility that osmotically active substances re-

leased from muscle might alter systemic Posm sufficiently to contribute to variation in exercise hemodynamics, 25 healthy adults (mean age 26.4 years) underwent a standard graded treadmill exercise test (Bruce protocol). Blood pressure (BP) and Posm of arm venous blood was obtained at each stage and at peak exercise.

Pre-exercise Posm was 291.5t0.9 mosm/kg (mean?SE). The mean exercise duration time was 13.8 min. (range: 9.0 to

18.0). During exercise, a progressive increase in Posm

occurred at each stage (2.020.5 at Stage I to 17.7kl.l at

Stage V). At peak exercise, increases in Posm ranged from 8 to 29. The BP response at peak exercise was variable: mean BP rose in 12 and fell or was unchanged in 9 (range

-33 to +3? mmHg). Of those subjects with only modest in- creases in Posm (~20 mosm/kg), 10 of 11 had elevated mean BP at peak exercise (mean +14.5?3.9 mmHg, range -11 to +37); whereas 8 of 10 subjects with marked increases in Posm (>20 mosm/kg) demonstrated a fall or no change in mean BP at peak (mean -4.Oi4.4, range -33 to +18) (pc.01).

Thus systemic hyperosmolality occurs during vigorous

graded exercise. The extent to which Posm rises appears to be a factor in the BP response and may in part con- tribute to the individual hemodynamic variability ob-

served.

CORONARY ARTERY LESIONS ASWCIATED WITH UNSTABLE ANGINA

James B. Caulfield, MD; Herman K. Gold, MD; Robert C.

Leinbach, MD, Massachusetts General Hospital, Boston,Mass.

15-40% of the cases of unstable angina (UA) develop an

acute myocardial infarct (AMI). This study was undertaken

to determine whether any morphologic alteration in coron-

ary arteries is associated with UA. The major coronary arteries from 40 autopsied patients (pts) were perfused,

fixed and sectioned at 2 mm intervals. Light microscopic

slides were prepared of each plaque. The 40 pts consis-

ted of 11 with no symptoms of coronary artery disease, 10

pts with AMI and UA, IO with AMI without preceding UA and

9 consecutive AMI pts examined before reference to antece-

dent history. Thirty-three morohologic criteria were

evaluated as either present or absent, or graded O-3+ when

appropriate. These data were transferred to tape and a computer used to orint out the data in various configura-

tions.

Thirteen of 15 pts with UA had multiple plaque hemorrhages

in 2 or more epicardial arteries and occlusive thrombosis

at the site of infarction. The hemorrhages were of var- iable age as evidenced by red cell lysis, hemosiderin de-

position, and varying amounts of granulation tissue. In

12 pts with AMI without orecedinq UA I1 showed a single

hemorrhaqe at the site of arterial thrombosis. nnly one pt had plaque hemorrhage in 2 eoicardial arteries. In the II control ots 2 small hemorrhages were found, The ana- tomic change common to all of these pts with AMI is plaque

hemorrhage with thrombosis. The UA pts were differentia- ted by the presence of multiple hemorrhages of varying

ages in 2 or more arteries suggesting an ongoing process

that culminated with a olaque hemorrhage, overlying

thrombus formation and infarction.

IDIOPATHIC PAROXYSMAL VENTRICULAR TACHYCARDIA IN NORMAL HEARTS: INTRACARDIAC ELECTRICAL, HEMODYNAMIC AND ANGIO- GRAPHIC OBSERVATIONS AND ASSESSMENT OF THERAPY John H. Chapman, MD; Joel P. Schrank, MD, FACC; Richard S. Crampton, MD, FACC, University of Virginia Medical Center, Charlottesville, Virginia, 22901.

In 6 patients with idiopathic paroxysmal ventricular

tachycardia (PVT), His bundle electrography verified right ventricular origin in 4 and left in 2. Response to atria1 pacing was normal. Four had intermittent type 1 and 2 had sustained type 2 PVT. In 4 with type 1 the vectorcardiogram was normal; 2 with type 2 showed Sl S2 S3 and terminal QRS loop delay. Three over age 40 years had syncope: 3 under age 25 had no syncope despite more pro-

longed bouts of PVT. All achieved NYHA Class I on tread- mill exercise; 3 had significantly less rise in systolic

pressure than predicted (p< 0.05); 3 overdrove the dys- rhythmia at sinus rates of 126-183% of control. At catheterization, normal hemodynamics and coronary angio- grams were seen in 6. Left ventricular (LV) cine- angiography, performed in 5, showed normal LV, mitral

valve and LV ejection fraction. All patients are well. Mean follow-up from ECG diagnosis is 2.9 (0.5-8.0) years.

One with type 2 PVT had no recurrence in 6 months on no

medication; 1 with type 1 PVT had no recurrence off coffee and tobacco without medication. ,In 3, diphenyl-

hydantoin 4.2-8.0 and propranolol 0.8-2.7 mg/kg/day controlled PVT. This combination yielded superior PVT control without side effects compared to quinidine and procainamide. In 1 followed elsewhere, propranolol 0.5 and procainamide 22.0 mg/kg/day abolished PVT, but not ventricular ectopy. Combined propranolol and diphenyl- hydantoin is the drug regimen of choice in idiopathic PVT.

CHRONOTROPIC INCOMPETENCE IN EXERCISE TESTING

Ching-Fong Chin, MD; Myrvin H. Ellestad, MD;

John C. Messenger, MD; *Memorial Hospital Medical

Center, Long Beach, Cal.

Chronotropic incompetence upon exercise, defined

as pulse rate for achieved workloads below the

95% confidence limits of the established normals

for age and sex was studied in 49 patients with

maximal stress testing and heart catheteriza-

tion. 23 exhibited a pulse rate response 2 SD

below the predicted mean. 16 showed ST segment

depression whereas 7 had normal ST segments. 5

of these 7, however, had coronary obstruction of

more than 50% and the other 2 had elevated LVEDP

at rest. 10 of the ischemic responders had

severe 3 vessel coronary disease, 2 had 2 vessel disease, 2 had 1 vessel disease and 2 had

elevated LVEDP at rest.

The other 26 subjects demonstrated a pulse rate

response below one SD. 18 showed normal ST seg-

ments and 8 had ST segment depression. 6 of the

normal ST responders had significant disease

whereas all 8 ischemic responders showed disease.

In 2700 subjects subjected to maximum stress

testing, there was a 40% incidence of coronary events in 4 years among 85 patients with chrono-

tropic incompetence and normal ST segments

compared to a 6% incidence among 1067 patients

with normal chronotropic response and ST seg-

ments.

A slow pulse rate response to exercise, even in

absence of ST segment depression, may be a

reliable index for coronary artery disease or LV

dysfunction.

126 January 1975 The American Journal of CARDIOLOGY Volume 35