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Indirect assessment of coronary artery bypass grafts
ABSTRACTS
left ventriculography, coronary blood flow, myocardial lactate extraction, and coronary sinus : arterial creatine phosphokinase (CPK) gradients were studied immediately before surgery. Coronary arteriography demonstrated 3-vessel obstruction (>50%) in 11 of 15. Coronary blood ilow, using a constant antipyrine infusion method, showed abnormally low values, averaging 78 cc/100 g per min 4 21 (normal 92-120). Myocardial lactate production was observed in 13 of 15. Lactate production occurred at rest in 3 and during controlled tachycardia (lOO-120imin) in 10. A coronary sinus : arterial CPK gradient was observed in all cases. Two to 7 days after surgery, restudy showed coronary blood flow to increase from 78 to 135 cc/100 g per min (P
Fifty-seven patients (mean age 50 2 1.4 SE) were studied before and after coronary artery bypass graft surgery (CABG) utilizing indirect techniques. Fifty had at least 1 myocardial infarction preoperatively. Phonocardiograms, carotid arterial tracings, apex cardiograms and electrocardiograms were obtained preoperatively in all and 2 weeks after CABG (49) and 2 to 4 months after CABG (32). Cardiac catheterization and angiographic studies demonstrated significant (>70% narrowing) 3-vessel coronary artery disease (CAD) in 13, 2-vessel CAD in 35 and l-vessel CAD in 9. There was generalized reduction in left ventricular (LV) contractility in 8 and marked reduction in 1 or more localized areas in 36. Only 1 patient preoperatively had significant mitral regurgitation (MR) . Fourth heart sounds (S4’s) were present preoperatively in 56, 2 weeks after CABG in 47 of 49 studied (no significant difference, NS), and 2 to 4 months after CABG in 31 of 32 studied (NS). Third heart sounds (S3’s) were present in 30 preoperatively, in 30 of 49 2 weeks post-CABG (NS), and in 20 of 32 at 2-4 months (NS). In 9 new S3’s developed 2 weeks after CABG but in 9 the pre-CABG S3’s disappeared. Before CABG, 10 had systolic murmurs compatible with but not specific for MR, 2 had paradoxically split second heart sounds (Sz’sj at rest, and 37 had early systolic sounds suggesting early clicks or split first heart sounds. There was no significant change in the incidence of systolic murmurs, splitting of S2’s or early systolic sounds after CABG. These studies demonstrate the following: (1) CABG’s do not in the relatively early postoperative period completely reverse areas of reduced LV compliance which are responsible for the genesis of S4’s; (2)
VOLUME
29, FEBRUARY
1972
the influence of CABG is more variable regarding presence or absence of S3’s, but a few patients acquire new S3’s in the early post-BABG period; and (3) early systolic sounds are relatively common in patients with CAD, whereas paradoxical splitting of S2’s are uncommon at rest. Neither changed significantly after CABG. Protective Zone for Ventricular
Fibrillation
EDUARDO SEROPPIAN, MD, FACC; MARSHALL WOLF, MD*; BERNARD LOWN, MD, FACC; JOHN TEMTE, MD, PhD; ARTHUR GARFEIN, MSEE; R. VERRIER, PhD, Boston, Massachusetts
The ventricular vulnerable period (VP) is a 20 to 40 msec interval during ventricular repolarization when a 0.5 to 1.0 watt set discharge (S,) can precipitate ventricular fibrillation (VF). Termination of VF even if attempted within seconds requires large energies (50100 watt set). We have observed that VF produced by S1 is prevented if a second 0.5-1.0 watt set pulse (S,) , is coupled to S1. To be effective, S, must be delivered within a critical interval of time following Si, which we define as the protective zone (PZ) . S2 is ineffective in preventing VF if delivered before or after the PZ. This PZ has been observed in each of 30 mongrel dogs with both transthoracic (underdamped capacitor) and endocardial (right ventricular unipolar square wave) discharges. The PZ begins 10 to 40 msec after the end of the VP and has a duration of 25 to 90 msec. The duration of the PZ varies inversely with heart rate (60 to 300 beats/min). For a given heart rate, the time of onset of the PZ (inner boundary) is fixed in the cardiac cycle and is independent of the location of S, in the VP. In contrast, the outer boundary of the PZ maintains a constant relation to S1. It is suggested that the PZ reflects the disparity in the duration of repolarization of the ventricular myocardium and the specialized conducting system. Effects of Conditioning on Plasma Catecholamine Levels During Exercise in Patients with Coronary Artery Disease STEVEN WOLFSON*; ANTONIO E. ACOSTA; LESLIE I. ROSE; ALFRED F. PARISI; KARL ENGELMAN, San Antonio, Texas, and Philadelphia, Pennsylvania
_As an index of adrenergic activity during exercise (Ex) , arterial plasma catecholamine (Cat) levels were measured before and after a program of physical conditioning (Cond) . All 7 patients studied had a positive Ex test, and either angina or a remote myocardial infarction. They were tested on a bicycle ergometer to angina or fatigue, and then trained on the bicycle for 10 to 18 weeks, 3 to 5 days/week. Cat levels were determined by a double-isotope derivative method. A Cond effect, with increased predicted max VOz (PMVO.,), was seen in 5. During Ex at 400 to 700 kpm/min, heart rate (HR) decreased from 147.3 + 6.5 to 126.7 2 6.4 P
297
left ventriculography, coronary blood flow, myocardial lactate extraction, and coronary sinus : arterial creatine phosphokinase (CPK) gradients were studied immediately before surgery. Coronary arteriography demonstrated 3-vessel obstruction (>50%) in 11 of 15. Coronary blood ilow, using a constant antipyrine infusion method, showed abnormally low values, averaging 78 cc/100 g per min 4 21 (normal 92-120). Myocardial lactate production was observed in 13 of 15. Lactate production occurred at rest in 3 and during controlled tachycardia (lOO-120imin) in 10. A coronary sinus : arterial CPK gradient was observed in all cases. Two to 7 days after surgery, restudy showed coronary blood flow to increase from 78 to 135 cc/100 g per min (P
Fifty-seven patients (mean age 50 2 1.4 SE) were studied before and after coronary artery bypass graft surgery (CABG) utilizing indirect techniques. Fifty had at least 1 myocardial infarction preoperatively. Phonocardiograms, carotid arterial tracings, apex cardiograms and electrocardiograms were obtained preoperatively in all and 2 weeks after CABG (49) and 2 to 4 months after CABG (32). Cardiac catheterization and angiographic studies demonstrated significant (>70% narrowing) 3-vessel coronary artery disease (CAD) in 13, 2-vessel CAD in 35 and l-vessel CAD in 9. There was generalized reduction in left ventricular (LV) contractility in 8 and marked reduction in 1 or more localized areas in 36. Only 1 patient preoperatively had significant mitral regurgitation (MR) . Fourth heart sounds (S4’s) were present preoperatively in 56, 2 weeks after CABG in 47 of 49 studied (no significant difference, NS), and 2 to 4 months after CABG in 31 of 32 studied (NS). Third heart sounds (S3’s) were present in 30 preoperatively, in 30 of 49 2 weeks post-CABG (NS), and in 20 of 32 at 2-4 months (NS). In 9 new S3’s developed 2 weeks after CABG but in 9 the pre-CABG S3’s disappeared. Before CABG, 10 had systolic murmurs compatible with but not specific for MR, 2 had paradoxically split second heart sounds (Sz’sj at rest, and 37 had early systolic sounds suggesting early clicks or split first heart sounds. There was no significant change in the incidence of systolic murmurs, splitting of S2’s or early systolic sounds after CABG. These studies demonstrate the following: (1) CABG’s do not in the relatively early postoperative period completely reverse areas of reduced LV compliance which are responsible for the genesis of S4’s; (2)
VOLUME
29, FEBRUARY
1972
the influence of CABG is more variable regarding presence or absence of S3’s, but a few patients acquire new S3’s in the early post-BABG period; and (3) early systolic sounds are relatively common in patients with CAD, whereas paradoxical splitting of S2’s are uncommon at rest. Neither changed significantly after CABG. Protective Zone for Ventricular
Fibrillation
EDUARDO SEROPPIAN, MD, FACC; MARSHALL WOLF, MD*; BERNARD LOWN, MD, FACC; JOHN TEMTE, MD, PhD; ARTHUR GARFEIN, MSEE; R. VERRIER, PhD, Boston, Massachusetts
The ventricular vulnerable period (VP) is a 20 to 40 msec interval during ventricular repolarization when a 0.5 to 1.0 watt set discharge (S,) can precipitate ventricular fibrillation (VF). Termination of VF even if attempted within seconds requires large energies (50100 watt set). We have observed that VF produced by S1 is prevented if a second 0.5-1.0 watt set pulse (S,) , is coupled to S1. To be effective, S, must be delivered within a critical interval of time following Si, which we define as the protective zone (PZ) . S2 is ineffective in preventing VF if delivered before or after the PZ. This PZ has been observed in each of 30 mongrel dogs with both transthoracic (underdamped capacitor) and endocardial (right ventricular unipolar square wave) discharges. The PZ begins 10 to 40 msec after the end of the VP and has a duration of 25 to 90 msec. The duration of the PZ varies inversely with heart rate (60 to 300 beats/min). For a given heart rate, the time of onset of the PZ (inner boundary) is fixed in the cardiac cycle and is independent of the location of S, in the VP. In contrast, the outer boundary of the PZ maintains a constant relation to S1. It is suggested that the PZ reflects the disparity in the duration of repolarization of the ventricular myocardium and the specialized conducting system. Effects of Conditioning on Plasma Catecholamine Levels During Exercise in Patients with Coronary Artery Disease STEVEN WOLFSON*; ANTONIO E. ACOSTA; LESLIE I. ROSE; ALFRED F. PARISI; KARL ENGELMAN, San Antonio, Texas, and Philadelphia, Pennsylvania
_As an index of adrenergic activity during exercise (Ex) , arterial plasma catecholamine (Cat) levels were measured before and after a program of physical conditioning (Cond) . All 7 patients studied had a positive Ex test, and either angina or a remote myocardial infarction. They were tested on a bicycle ergometer to angina or fatigue, and then trained on the bicycle for 10 to 18 weeks, 3 to 5 days/week. Cat levels were determined by a double-isotope derivative method. A Cond effect, with increased predicted max VOz (PMVO.,), was seen in 5. During Ex at 400 to 700 kpm/min, heart rate (HR) decreased from 147.3 + 6.5 to 126.7 2 6.4 P
297