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Criteria for the validity of the rise in left ventricular end diastolic pressure following pacing induced angina
ABSTRACTS
PACEMAKER CURRENT IN CARDIAC PURKINJE FIBERS: EVIDENCE FOR DEPENDENCE ON THE NA-K PUMP Ronald S. Aronson, MD; Jeremiah M. Gelles, MD; Brian F. Hoffman, MD, College of Physicians & Surgeons of Columbia University, New York, New York.
CRITEFUAFOR THE VALIDITYOF THE RISE IN LEFT VENTRICULAR END DIASTOLICPRESSUREFOLLOWINGPACING INDUCEDANGINA RaphaelBalcon,MD, FACC; Roger Wilkinson,XB; WarrenWalsh,MB, MRACP;AnthonyRickards,MB, MX?. LondonChest Hospital,London,hgland.
We have previously shown that ouabain greatly diminishes or abolishes the current (IK2 or pacemaker current) presently considered to be responsible for spontaneous diastolic depolarization in Purkinje fibers of the sheep. Since ouabain is a relatively specific inhibitor of the Na-K pump we were led to test the effect of other pump inhibitors on IK2. The effects of substitution of Li for Na and of 2,4_dinitrophenol (DliP) on IK2 were studied using a two-microelectrode voltage clamp technique in shortened cardiac Purkinje fibers of the sheep. Isolated fibers were perfused with Tyrode solution (K, 4.Omi4, T, 36'C) the Na of which was isosmotically replaced with Li (except for 12mM NaHCO ) or to which DNP, 0.2mM, was added under test cond 3. tlons. Exposure to Li Tyrode solution greatly reduced or abolished IK2. This current reappeared on readmission of Na Tyrode DNP also greatly attenuated IK2. Action posolution. tentials which under control conditions showed spontaneous diastolic depolarization did not show such activity after exposure to Li Tyrode solution or to DNP. The dramatic reduction or abolition of the pacemaker current under various conditions that inhibit the Na-K pump suggests that the integrity of this pump is in some way necessary for the generation of this current.
85 patientsbeing investigatedfor anginahave been studied at cardiaccatheterisation.With continuousmeasurement of LVEDP the heart rati.(HR) was increasedby pacing from an initialrate of 100 bpm, increasingby 10 bpm each minute. If AV block occurredduringFfApacing,the catheterwas advancedto the RV and the test continued until either the maximumrate of 160 bpm was reachedor the patientcomplainedof cardiacpain. At the end of each minute the pacemakerwas switchedoff and LVEDP recordedfor 10 beats in sinus rhythm. h patientgroups were identified. A (h7 patients) with CAD who developed anginaduringpacing,B (12 patients)with CAD without inductionof angina,C (13) and D (13) had no CAD but group C complainedof pain duringpacing. Group D were considerednormal. No differentiation betweenthe groups was apparentfrom LVEDP duringpacing. Followingswitchoff of pacing the RR interval,pre a, a wave and post a pressureswere measuredin each patient. The relationship betweenpre a and a (r-0.96)and pre a and post a (r=0.95) remainsconstantfor any individual. With increasedHB there was no significantchangein LVEDP from controlin groups B, C, D. Only in group A at the inductionof angina (p 0.001) and 10 beats before (p O.OS'j did LVEDP rise significantly.The magnitudeof the rise in LVEDP is proportionalto the HR attainedbefore switch off of pacing. Thus a rise of lmm Hg at 100-120bpm, 3mm Hg at 130-150bpm and Smm Hg at 160-180 bpm was seen in 70% of group A and only 23% of group D (normal).These figuresprovidemore accurateguidelinesfor the definition of an abnormalLV responseto pacing.
RELATION OF EARLY POSTOPERATIVE MYOCARDIAL INFARCTION TO PATENCY OF AORTOCORONARY BYPASS GRAFTS AND TO UNGRAFTED CORONARY ARTERIES Jose L. Assad-Morell, MD; Gerald T. Gau, MD, FACC; Robert L. Frye, MD, FACC; Daniel C. Connolly, MD, FACC; George D. Davis, MD; Gordon K. Danielson, MD, FACC, Mayo Clinic and Mayo Foundation, Rochester, Minnesota.
EFFECTS OF NITROGLYCERIN ON REGIONAL LEFT VENTRICULAR LENGTH-TENSION RELATIONS AFTER CORONARY OCCLUSION Vidya S. Banka, MD; Monty Bodenheimer, MD; Richard H. Helfant, MD, FACC, Presbyterian-University of Pennsylvania Medical Center, Philadelphia, Pennsylvania
To study the incidence of early transmural myocardial infarction (TMI) after saphenous-vein bypass graft and its relationship to graft patency and diseased ungrafted coronary arteries, we analyzed the preoperative and postoperative (PO) electrocardiograms (ECG) and vectocardiograms (VCG) of 572 patients (pts) operated on from 1969-1972 inclusive. Standard ECG and VCG criteria for diagnosis of TM1 were used, and the angiograms of pts with early PO-TM1 were reviewed. TMIs occurred in 67 (12%) of the pts. Nearly all of them were documented within 24 hours after operation, and the rest within 72 hours. The pts comprised15 (5%) of the 295 who had had TM1 prior to surgery and 52 (19%) of the 277 who had not. There were 47 TMIs within the distribution of the grafted vessels and 17 in the distributions of vessels that had been severely diseased but not grafted. (Three were in the distributions of angiographically normal vessels.) Repeat angiography, performed in 36 of the 67 case.sof early PO-TMZ, showed that 32 of the infarcts in this group were within the distribution of the grafted vessel. The grafts were patent in 16 of these pts and there was graft occlusion in 16. The 12% risk of early postoperative TM1 is substantial. Clearly, the occurrence of early PO-TM1 is not a reliable indication of graft occlusion, for 25% of all TMIs were in the distribution of diseased but ungrafted arteries, and among the group of 32 who developed TM1 in the distribution of the grafted artery and were studied angiographitally afterward, as many grafts were patent as occluded.
124
January
1974
The American
Journal
of CARDIOLOGY
Controversy has existed concerning the value of nitroglycerin (TNG) in acute coronary disease. To better define this issue, the effects of TNG (3Oug/Kg intravenously) on local tension and length characteristics of the ischemic (IZ), border (BZ) and nonischemic (NZ) zones of the left ventricle were studied in 10 open chested dogs using Walton-Brodie strain gauges and mercury-insilastic segment length gauges. In the BZ, the pre-ejection tension (PET) increased by 30.9 + 10.9%, ejection tension (ET) by 44.0 + 8.5% .nnd the rate of tension rise (DT/dt) by 41.7 2 7.0% (p
Volume
33
PACEMAKER CURRENT IN CARDIAC PURKINJE FIBERS: EVIDENCE FOR DEPENDENCE ON THE NA-K PUMP Ronald S. Aronson, MD; Jeremiah M. Gelles, MD; Brian F. Hoffman, MD, College of Physicians & Surgeons of Columbia University, New York, New York.
CRITEFUAFOR THE VALIDITYOF THE RISE IN LEFT VENTRICULAR END DIASTOLICPRESSUREFOLLOWINGPACING INDUCEDANGINA RaphaelBalcon,MD, FACC; Roger Wilkinson,XB; WarrenWalsh,MB, MRACP;AnthonyRickards,MB, MX?. LondonChest Hospital,London,hgland.
We have previously shown that ouabain greatly diminishes or abolishes the current (IK2 or pacemaker current) presently considered to be responsible for spontaneous diastolic depolarization in Purkinje fibers of the sheep. Since ouabain is a relatively specific inhibitor of the Na-K pump we were led to test the effect of other pump inhibitors on IK2. The effects of substitution of Li for Na and of 2,4_dinitrophenol (DliP) on IK2 were studied using a two-microelectrode voltage clamp technique in shortened cardiac Purkinje fibers of the sheep. Isolated fibers were perfused with Tyrode solution (K, 4.Omi4, T, 36'C) the Na of which was isosmotically replaced with Li (except for 12mM NaHCO ) or to which DNP, 0.2mM, was added under test cond 3. tlons. Exposure to Li Tyrode solution greatly reduced or abolished IK2. This current reappeared on readmission of Na Tyrode DNP also greatly attenuated IK2. Action posolution. tentials which under control conditions showed spontaneous diastolic depolarization did not show such activity after exposure to Li Tyrode solution or to DNP. The dramatic reduction or abolition of the pacemaker current under various conditions that inhibit the Na-K pump suggests that the integrity of this pump is in some way necessary for the generation of this current.
85 patientsbeing investigatedfor anginahave been studied at cardiaccatheterisation.With continuousmeasurement of LVEDP the heart rati.(HR) was increasedby pacing from an initialrate of 100 bpm, increasingby 10 bpm each minute. If AV block occurredduringFfApacing,the catheterwas advancedto the RV and the test continued until either the maximumrate of 160 bpm was reachedor the patientcomplainedof cardiacpain. At the end of each minute the pacemakerwas switchedoff and LVEDP recordedfor 10 beats in sinus rhythm. h patientgroups were identified. A (h7 patients) with CAD who developed anginaduringpacing,B (12 patients)with CAD without inductionof angina,C (13) and D (13) had no CAD but group C complainedof pain duringpacing. Group D were considerednormal. No differentiation betweenthe groups was apparentfrom LVEDP duringpacing. Followingswitchoff of pacing the RR interval,pre a, a wave and post a pressureswere measuredin each patient. The relationship betweenpre a and a (r-0.96)and pre a and post a (r=0.95) remainsconstantfor any individual. With increasedHB there was no significantchangein LVEDP from controlin groups B, C, D. Only in group A at the inductionof angina (p 0.001) and 10 beats before (p O.OS'j did LVEDP rise significantly.The magnitudeof the rise in LVEDP is proportionalto the HR attainedbefore switch off of pacing. Thus a rise of lmm Hg at 100-120bpm, 3mm Hg at 130-150bpm and Smm Hg at 160-180 bpm was seen in 70% of group A and only 23% of group D (normal).These figuresprovidemore accurateguidelinesfor the definition of an abnormalLV responseto pacing.
RELATION OF EARLY POSTOPERATIVE MYOCARDIAL INFARCTION TO PATENCY OF AORTOCORONARY BYPASS GRAFTS AND TO UNGRAFTED CORONARY ARTERIES Jose L. Assad-Morell, MD; Gerald T. Gau, MD, FACC; Robert L. Frye, MD, FACC; Daniel C. Connolly, MD, FACC; George D. Davis, MD; Gordon K. Danielson, MD, FACC, Mayo Clinic and Mayo Foundation, Rochester, Minnesota.
EFFECTS OF NITROGLYCERIN ON REGIONAL LEFT VENTRICULAR LENGTH-TENSION RELATIONS AFTER CORONARY OCCLUSION Vidya S. Banka, MD; Monty Bodenheimer, MD; Richard H. Helfant, MD, FACC, Presbyterian-University of Pennsylvania Medical Center, Philadelphia, Pennsylvania
To study the incidence of early transmural myocardial infarction (TMI) after saphenous-vein bypass graft and its relationship to graft patency and diseased ungrafted coronary arteries, we analyzed the preoperative and postoperative (PO) electrocardiograms (ECG) and vectocardiograms (VCG) of 572 patients (pts) operated on from 1969-1972 inclusive. Standard ECG and VCG criteria for diagnosis of TM1 were used, and the angiograms of pts with early PO-TM1 were reviewed. TMIs occurred in 67 (12%) of the pts. Nearly all of them were documented within 24 hours after operation, and the rest within 72 hours. The pts comprised15 (5%) of the 295 who had had TM1 prior to surgery and 52 (19%) of the 277 who had not. There were 47 TMIs within the distribution of the grafted vessels and 17 in the distributions of vessels that had been severely diseased but not grafted. (Three were in the distributions of angiographically normal vessels.) Repeat angiography, performed in 36 of the 67 case.sof early PO-TMZ, showed that 32 of the infarcts in this group were within the distribution of the grafted vessel. The grafts were patent in 16 of these pts and there was graft occlusion in 16. The 12% risk of early postoperative TM1 is substantial. Clearly, the occurrence of early PO-TM1 is not a reliable indication of graft occlusion, for 25% of all TMIs were in the distribution of diseased but ungrafted arteries, and among the group of 32 who developed TM1 in the distribution of the grafted artery and were studied angiographitally afterward, as many grafts were patent as occluded.
124
January
1974
The American
Journal
of CARDIOLOGY
Controversy has existed concerning the value of nitroglycerin (TNG) in acute coronary disease. To better define this issue, the effects of TNG (3Oug/Kg intravenously) on local tension and length characteristics of the ischemic (IZ), border (BZ) and nonischemic (NZ) zones of the left ventricle were studied in 10 open chested dogs using Walton-Brodie strain gauges and mercury-insilastic segment length gauges. In the BZ, the pre-ejection tension (PET) increased by 30.9 + 10.9%, ejection tension (ET) by 44.0 + 8.5% .nnd the rate of tension rise (DT/dt) by 41.7 2 7.0% (p
Volume
33