Bundle of His electrograms: “Fact of ArtiFACT”

ABSTRACTS

were compared to those of 13 patients with inferior infarction (IQ), 25 patients with anterior infarction (AQ) and 9 patients with anterior-inferior infarction (A-IQ). Results were left-ventricular end-diastolic pressure (LVEDP), No& 11, IQ 11, A& 18 (P , A-IQ 88% (P
Natural History of Severe Proximal Coronary Disease as Defined by Cineangiography (200 Patients, 7 Year Followup) CARL H. MOBERG, MD; JOEL S. WEBSTER, SONES, Jr., MD, FACC, Cleveland, Ohio

MD*;

F. MASON

Determining the survival rate in patients with severe proximal coronary lesions may help evaluate the efficacy of some present and future forms of surgical therapy. Mortality was reviewed in 200 patients with 80 to lOOc/; occlusive lesions in the proximal coronary tree as defined by selective angiography. Patients with marked cardiomegaly, congestive heart failure or severe left ventricular impairment by left ventriculography were excluded, leaving only patients with normal or moderately impaired left ventricular function in the study. Eighty-four patients with l-vessel, 82 with 2-, and 34 with 3-vessel involvement were followed up for ‘7 to 9 years. Single vessel anterior descending disease has a 4% yearly attrition rate or 30.5:/r 7 year mortality (11 of 36). Single right coronary or circumflex lesions demonstrated only a 1.8% yearly death rate or 12.5% in 7 years (6 of 48). Patients with 2- and 3-vessel disease had a 44 % (36 of 82) and 7074 (24 of 34) 7 year mortality rate, respectively. Survival in the group with anterior descending artery involvement was correlated with collateralization and anatomic location of the lesion. Of 10 patients with 10054 occlusion of the anterior descending artery, 4 with faint or no collaterals died and 6 with excellent collateralization survived. Lesions above the first major septal perforator resulted in a 36yc mortality (5 of 14) : lesions below the perforator produced a 27:( mortality (6 of 22). Survival is related to the number of vessels involved and single vessel anterior descending disease has a lower, but significant, yearly attrition rate. Collateral blood supply 282

to the totally occluded anterior pears to increase survival. Bundle E. NEIL MELBIN.

of His Electrograms:

descending

“Fact

MOORE, DVM, PhD, FACC*, VMD, PhD, CCSU, Philadelphia,

artery

ap-

of ArtiFACT” J. F. SPEAR, Pennsylvania

PhD;

J.

There are 3 criteria which help define whether or not one is truly recording electrical activity from the bundle of His, namely (1) anatomic location of the electrode(s) , (2) configuration of the electrical complex, and (3) time of onset of depolarization within the P-R interval. When one uses the catheter technique to record bundle of His electrograms (BH) it is necessary to rely almost entirely on the time at which the SUSpected BH electrogram occurs. These studies demonstrate 4 methods to verify BH catheter recordings by (1) pacing the atrium at rapid rates, (2) introducing early premature atria1 beats, (3) increasing vagal tone, and (4) driving through the BH catheter. The difficulty and methods of distinguishing BH electrograms from (a) atria1 depolarization complexes, (b) atria1 repolarization complexes, and (c) mechanical artifacts are demonstrated. Amplifier band pass filter settings and electrode configuration played the most prominent role in governing BH electrogram configuration. Filters with different roll-off characteristics (including log), band widths and center frequencies were compared with d-c-recorded BH electrograms. The ability to enhance artifacts or BH electrograms, or both, was demonstrated. The influence of bipolar electrode configurations demonstrated the variations in BH potentials caused by variations in (a) interelectrode distances, (b) recording area of the electrodes, (c) proximity to BH tissue, and (d) spatial orientation of bipolar electrodes. These studies emphasize the caution required to define accurately a BH electrogram recorded with a catheter electrode. Effects of Propranolol and L-Norephinephrine Acute Myocardial Infarction in Man

in

HILTRUD MUELLER, MD, FACC’; STEPHEN lvl. AYRES, FACC, WILLIAM J. GRACE, MD, FACC, New York, New York

MD,

L-norephinephrine (L-NE) and propranolol (Prop) could theoretically improve myocardial oxygenation in acute myocardial infarction (AMI) by either increasing oxygen delivery (L-NE) or decreasing O1! demand (Prop). L-NE strikingly increased lactate utilization in 8 patients with myocardial infarction shock by increasing coronary perfusion pressure and blood flow. In contrast, the response to L-NE varied considerably in AM1 without shock, for reasons probably related to more active coronary autoregulation of the noninfarcted myocardium. Since increasing perfusion pressure did not consistently improve myocardial 0, availability in these patients, we evaluated the effect of Prop, an agent decreasing cardiac work and OZ requirements. Prop (56 CLg/kg per min) significantly decreased mean aortic pressure, time-tension index and probably contractility with little effect on heart rate in 10 patients with normal left atria1 pressure and subnormal cardiac indexes. L-NE (0.113 pg/kg per min), in the same group, increased cardiac afterload. Prop appeared to decrease OZ requirements since myocardial lactate and pyruvate extractions improved in face of decreased 0, consumption and blood flow. Free fatty acids (FFA) The American

Journal

of CARDIOLOGY