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Visualization of myocardial perfusion using application of digital radiographic techniques to selective coronary arteriography
ABSTRACTS
ENDOCARDIAL MAPPING DURING SINUS RHYTHM IN PATIENTS WITH RECURRENT SUSTAINED LIFE-THREATENING VENTRICULAR ARRHYTHMIAS. Joaquin G. Arciniegas, MD; Vance J. Plumb, MD, FACC; Robert B. Karp, ND, FACC; Samuel H. Zirmsern,MD; Richard W. Henthorn, ND; Albert L. Waldo, MD, FACC, Dept. of Medicine, UAB, Birmingham, Alabama. Intraoperative endocardial mapping during sinus rhythm was performed in 27 patients (pts) with recurrent sustained All pts had history of transventricular arrhythmias. mural myocardial necrosis and 26/27 pts had atherosclerotic coronary artery disease. Three simultaneous bipolar local endocardial electrograms were obtained from at least 20 sites in each pt following a predetermined anatomical grid. Local activation times were measured in relation to the onset of the QRS in simultaneously recorded surface Areas devoid of electrical activity were ECG leads. recorded in all pts (flat electrograms) and in 26 pts characteristic abnormalities of the local electrogram were also found. Fractionation of the bipolar local electrogram defined as polyphasic primary low amplitude deflections lasting at least 50 msec was found in 22 pts (mean number of sites per pt = 9). Double potentials defined as electrograms with two clearly separated deflections, the second one occurring at least 50 msec after the onset of the QRS in the surface ECG, were found in 18 pts (mean number of sites per pt = 5). Fractionation and double potentials were recorded in the same pt but in different sites in 14 instances. Visual inspection of the endocardium could not differentiate areas devoid of electrical activity (flat electrograms) from areas exhibiting fractionation and double potentials. In conclusion, intraoperative endocardial mapping during sinus rhythm identified areas with abnormal electrical activity impossible to locate by visual inspection that may underlie the development of sustained ventricular tachyarrhythmias.
MONOFORM VENTRICULAR TACHYCARDIAS DUE TO INCOMPLETE REPERFUSION - MAPPING AND MECHANISMS. Eugene Downar, MD; Ian Parson, PhD; Dept. of Medicine, University of Toronto, Toronto, Canada. In 13 in situ hearts (9 canine 4 porcine) 6 episodes of sustained monoform ventricular tachycardia were produced by transient release of a LAD occlusion after 12-24 minutes; These reperfusion tachycardias were mapped using 112 transmural multipolar needles and a videomultiplexing system previously described. Reperfusion caused responsiveness to return first to the epicardium then extend within a few beats to the subendocardium whence the first ventricular ectopics originated. When established all six ventricular tachycardias appeared to be monofocal in origin on an on-line video display of activation at a subepicardial level. Off-line maps of simultaneous epicardial and endocardial activation revealed that four of the tachycardias' were due to macro-reentry and two to abnormal automaticity or micro-re-entry within the ischemic myocardium. In the re-entrant arrhythmias the re-entrant pathway involved slow conduction subepicardially into the ischemic region then transmurally to engage the endocardium overlying the ischemic region. In one instance, a tachycardia switched abruptly from one stable morphology to another within a single cycle. This was shown to be due to reversal in direction of activation within the slowly conducting ischemic subepicardium. In conclusion incomplete reperfusion of ischemic myocardium produces sustained monoform ventricular tachycardias of macro-x-entrant as well as automatic or micro-re-entrant origin.
TUESDAY, APRIL 27, 1982 AM CORONARY ANGIOGRAPHY AND CORONARY BLOOD FLOW 8:30- 10:00 VISUALIZATION OF MYOCARDIAL PERFUSION USING APPLICATION OF DIGITAL RADIOGRAPHIC TECHNIQUES TO SELECTIVE CORONARY ARTERICGRAPHY Robert A. Vogel, MD, Michael T. LeFree, BS, Bertram Pitt, MD, FACC, Veterans Administration Medical Center, Ann Arbor, Michigan Selective coronary arteriography has been used almost exclusively for the assessment of coronary artery anatomy. We have developed a new technique which enables this important clinical test to visualize myocardial perfusion in addition. Selective arteriography is performed in any projection in the usual manner except for the use of fixed kV, mA and pulse width cineradio,graphy. ECG timed end-diastolic frames are then digitized into 256 x 256 B-bit pixels by a real-time video digitizer and a minicomputer using either a video disk recorder or 35 mm film for intermediate storage. Consecutive end-diastolic frames are then subtracted, pixels with negative values being set to 0. This yields a series of 5-8 images which depict the appearance of contrast into the arterial, capillary and venous phases of transit through the myocardium in sequential isolated fashion. A program finally assembles these images into a single composite bifunctional image in which the maximum appearance of contrast within each pixel is intensity coded, and the time from initial injection to the maximum appearance of contrast for each pixel is color coded. The resultant bifunctional image clearly demonstrates both the amount and the temporal dynamics of regional perfusion. Regional hypoperfusion has been clinically observed to have characteristic patterns of temporal passage. This new technique allows assessment of direct and collateral, and native and vein graft perfusion which has been made visible within the arteriographic technique by application of digital radiographic methods.
KND-DIASTOLIC MASKSUBTRACTION: AN IMPROVEDMETHODFOR DI3F’LAYIffi WALL l@TICMABNORMALITIKS USINGA DIGITAL
~AMXOCRAPHT COIUVERsYsTKM Warren D. Johnston, MD; Jonathan Tobis, MD, FACC;Orhan Nalcioglu, PhD; J. Anthony Seibert, PhD; Werner W. Roeck Lloyd T. Iseri, MD, FACC;Uri Klkayma, MD;Walter L. Henry, MD, University of Calfornia, Irvine, Orange, CA Assessment of wall motion abnormalities may be time consting because it is often necessary to trace the outline of end-diastolic and end-systolic ventriculographic images in order to adequately evaluate wall motion. To simplify this procedure, we used a prototype digital angiography canputer system to obtain an image which suunarizes and displays wall motion on one franc. Previously recorded digital intravenous angiogrmns were redigitized by the computer. The iodine-filled enddiastolic image of the left ventricle was used as a mask and subtracted frcm each ensuing frame until end-systole. lhe resultant subtracted image at end-systole (or at any time during ventricular contraction or relaxation) displayed a white shell which represented the difference between the ventricular images at end-diastole and end-systole. This shell image allcwed direct visualization of ventricular wall motion and quantitation of end-diastolic, end-systolic and stroke volumes. In 8 patients (pts) with wall motion abnormalities on standard tine ventriculograms, akinetic segments were depicted as “holes” in the shell while dyskinetic segments were seen as black instead of white changes in the shell. In 7 pts without wall motion abnormalities, a complete white shell was seen. lhus, end-diastolic mask subtraction with digital angiography is a clinically pranising method for slmnarizing wall motion abnormalities on a single fraae fran which end-diastolic, end-systolic and stroke voluoes can be computed.
March 1992
The American Journal of CARDIOLOGY
Volume 49
935
ENDOCARDIAL MAPPING DURING SINUS RHYTHM IN PATIENTS WITH RECURRENT SUSTAINED LIFE-THREATENING VENTRICULAR ARRHYTHMIAS. Joaquin G. Arciniegas, MD; Vance J. Plumb, MD, FACC; Robert B. Karp, ND, FACC; Samuel H. Zirmsern,MD; Richard W. Henthorn, ND; Albert L. Waldo, MD, FACC, Dept. of Medicine, UAB, Birmingham, Alabama. Intraoperative endocardial mapping during sinus rhythm was performed in 27 patients (pts) with recurrent sustained All pts had history of transventricular arrhythmias. mural myocardial necrosis and 26/27 pts had atherosclerotic coronary artery disease. Three simultaneous bipolar local endocardial electrograms were obtained from at least 20 sites in each pt following a predetermined anatomical grid. Local activation times were measured in relation to the onset of the QRS in simultaneously recorded surface Areas devoid of electrical activity were ECG leads. recorded in all pts (flat electrograms) and in 26 pts characteristic abnormalities of the local electrogram were also found. Fractionation of the bipolar local electrogram defined as polyphasic primary low amplitude deflections lasting at least 50 msec was found in 22 pts (mean number of sites per pt = 9). Double potentials defined as electrograms with two clearly separated deflections, the second one occurring at least 50 msec after the onset of the QRS in the surface ECG, were found in 18 pts (mean number of sites per pt = 5). Fractionation and double potentials were recorded in the same pt but in different sites in 14 instances. Visual inspection of the endocardium could not differentiate areas devoid of electrical activity (flat electrograms) from areas exhibiting fractionation and double potentials. In conclusion, intraoperative endocardial mapping during sinus rhythm identified areas with abnormal electrical activity impossible to locate by visual inspection that may underlie the development of sustained ventricular tachyarrhythmias.
MONOFORM VENTRICULAR TACHYCARDIAS DUE TO INCOMPLETE REPERFUSION - MAPPING AND MECHANISMS. Eugene Downar, MD; Ian Parson, PhD; Dept. of Medicine, University of Toronto, Toronto, Canada. In 13 in situ hearts (9 canine 4 porcine) 6 episodes of sustained monoform ventricular tachycardia were produced by transient release of a LAD occlusion after 12-24 minutes; These reperfusion tachycardias were mapped using 112 transmural multipolar needles and a videomultiplexing system previously described. Reperfusion caused responsiveness to return first to the epicardium then extend within a few beats to the subendocardium whence the first ventricular ectopics originated. When established all six ventricular tachycardias appeared to be monofocal in origin on an on-line video display of activation at a subepicardial level. Off-line maps of simultaneous epicardial and endocardial activation revealed that four of the tachycardias' were due to macro-reentry and two to abnormal automaticity or micro-re-entry within the ischemic myocardium. In the re-entrant arrhythmias the re-entrant pathway involved slow conduction subepicardially into the ischemic region then transmurally to engage the endocardium overlying the ischemic region. In one instance, a tachycardia switched abruptly from one stable morphology to another within a single cycle. This was shown to be due to reversal in direction of activation within the slowly conducting ischemic subepicardium. In conclusion incomplete reperfusion of ischemic myocardium produces sustained monoform ventricular tachycardias of macro-x-entrant as well as automatic or micro-re-entrant origin.
TUESDAY, APRIL 27, 1982 AM CORONARY ANGIOGRAPHY AND CORONARY BLOOD FLOW 8:30- 10:00 VISUALIZATION OF MYOCARDIAL PERFUSION USING APPLICATION OF DIGITAL RADIOGRAPHIC TECHNIQUES TO SELECTIVE CORONARY ARTERICGRAPHY Robert A. Vogel, MD, Michael T. LeFree, BS, Bertram Pitt, MD, FACC, Veterans Administration Medical Center, Ann Arbor, Michigan Selective coronary arteriography has been used almost exclusively for the assessment of coronary artery anatomy. We have developed a new technique which enables this important clinical test to visualize myocardial perfusion in addition. Selective arteriography is performed in any projection in the usual manner except for the use of fixed kV, mA and pulse width cineradio,graphy. ECG timed end-diastolic frames are then digitized into 256 x 256 B-bit pixels by a real-time video digitizer and a minicomputer using either a video disk recorder or 35 mm film for intermediate storage. Consecutive end-diastolic frames are then subtracted, pixels with negative values being set to 0. This yields a series of 5-8 images which depict the appearance of contrast into the arterial, capillary and venous phases of transit through the myocardium in sequential isolated fashion. A program finally assembles these images into a single composite bifunctional image in which the maximum appearance of contrast within each pixel is intensity coded, and the time from initial injection to the maximum appearance of contrast for each pixel is color coded. The resultant bifunctional image clearly demonstrates both the amount and the temporal dynamics of regional perfusion. Regional hypoperfusion has been clinically observed to have characteristic patterns of temporal passage. This new technique allows assessment of direct and collateral, and native and vein graft perfusion which has been made visible within the arteriographic technique by application of digital radiographic methods.
KND-DIASTOLIC MASKSUBTRACTION: AN IMPROVEDMETHODFOR DI3F’LAYIffi WALL l@TICMABNORMALITIKS USINGA DIGITAL
~AMXOCRAPHT COIUVERsYsTKM Warren D. Johnston, MD; Jonathan Tobis, MD, FACC;Orhan Nalcioglu, PhD; J. Anthony Seibert, PhD; Werner W. Roeck Lloyd T. Iseri, MD, FACC;Uri Klkayma, MD;Walter L. Henry, MD, University of Calfornia, Irvine, Orange, CA Assessment of wall motion abnormalities may be time consting because it is often necessary to trace the outline of end-diastolic and end-systolic ventriculographic images in order to adequately evaluate wall motion. To simplify this procedure, we used a prototype digital angiography canputer system to obtain an image which suunarizes and displays wall motion on one franc. Previously recorded digital intravenous angiogrmns were redigitized by the computer. The iodine-filled enddiastolic image of the left ventricle was used as a mask and subtracted frcm each ensuing frame until end-systole. lhe resultant subtracted image at end-systole (or at any time during ventricular contraction or relaxation) displayed a white shell which represented the difference between the ventricular images at end-diastole and end-systole. This shell image allcwed direct visualization of ventricular wall motion and quantitation of end-diastolic, end-systolic and stroke volumes. In 8 patients (pts) with wall motion abnormalities on standard tine ventriculograms, akinetic segments were depicted as “holes” in the shell while dyskinetic segments were seen as black instead of white changes in the shell. In 7 pts without wall motion abnormalities, a complete white shell was seen. lhus, end-diastolic mask subtraction with digital angiography is a clinically pranising method for slmnarizing wall motion abnormalities on a single fraae fran which end-diastolic, end-systolic and stroke voluoes can be computed.
March 1992
The American Journal of CARDIOLOGY
Volume 49
935