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A comparison of three approaches for detecting body surface potential map abnormalities
ABSTRACTS
A COMPARISON OF THREE APPROACHES FOR D E T E C T I N G B O D Y SURFACE P O T E N T I A L M A P ABNORMALITIES . Hal Pham-Huy, M.Eng.; R6ginald Nadeau, MD, FACC" Ramesh Gulrajani, Ph.D.; Pierre Savard, D.Sc.A.; Fernand Roberge, Ph.D., Universit6 de Montreal, Montr6al, Canada.
MULTIPARAMETER MONITORING OF IMPLANTED CARDIAC PACEMAKERS. G. Frank O. Tyers, MD, FACC; Robert R. Brownlee, MSEE; Edward H. Williams, MD; Martin J. O'Neill, MD; Akira Nishimura, MD, FACC; Charles J. Del Marco, and Howard C. Hughes, VMD. Un. of Texas Medical Branch, Galveston, Tx.
Three approaches for detecting abnormalities in body surface potential maps (BSPMs) recorded from patients with myocardial infarction were compared. The BSPMs are generated by a minicomputer every 2.5 ms during QRS from 26 simultaneously recorded thoracic ECGs. All 3 approaches are based on detecting the deviations in certain parameters from control values, determined in our case from 40 normal subjects. The first approach emphasizes qualitative deviations in the trajectories of the BSPM extrema during QRS. This technique proved very effective on a test population of i0 normals and I0 cases of infarction, correctly classifying all normals and 9 infarcts. The second approach classifies a test subject as abnormal if any one of his 26 ECG lead waveforms deviates at any instant during QRS from the mean waveform for the particular lead plus or minus two standard deviations, these being determined from the 40 control subjects. This approach misclassified 8 of 10 normals. A final method was to obtain an instant by instant plot of the correlation coefficient (CC) between the mean BSPM during QRS for the 40 normals and that of the subject to be tested. Infarct cases were detected by at least one CC value falling below an envelope determined from the CC plots obtained by correlating the maps of all 40 normals with their own mean. Although 9 normals and 9 infarcts were correctly classified, inferior and posterior infarcts were usually only just detected with 2 or 3 CC values below the envelope. On the basis of these results the first approach is superior to the other two for detecting BSPM abnormalities.
Current pacemaker follow%up techniques to detect abnormalities and predict end of battery life (EOL) rely primarily on pacemaker rate decreases as indirect evidence of reduced battery voltage and capacity. The large number of major and minor rate changes that occur unrelated to battery voltage, the advent of rate programmability, phantom programming, and reductions in rate sensitivity with newer high current density electrodes mitigat e the usefulness of rate change for EOL prediction.
ENDOCARDIAL MAPPING HUN[AN HEARTS.
EVALUATION OF THE QRS COMPLEXES IN LEADS V4-V 6 AS INDICATORS OF THE SIZE OF ANTERIOR MYOCARDIAL INFARCTS DEFINED AT NECROPSY Raymond E. Ideker, MD, PhD, Galen S. Wagner, MD, Donald B. Hackel, MD, Sanford P. Bishop, DVM, PhD, Colin M. Bloor, MD, John T. Fallon, MD, PhD, Harry R. Phillips, MD, Keith A. Reimer, MD, PhD, Steven F. Roark, MD, William J. Rogers, MD, FACC, Robert M. Savage, MD, Ronald M. Selvester, MD. Duke Hosp., Durham NC, U. Ala. Med. Ctr., Birmingham, AL, UCSD Sch. of Med., La Jolla, CA, Mass. Gen. Hosp, Boston, MA, Rancho Los Amigos Hosp., Downey, CA.
IN I S O L A T E D
CANINE
AND
Rudolf T. van D a m , M . D . , F A C C , Dept. of Cardio[. and Clin. Physiol., University of A m s t e r d a m , and Interuniversitary Cardiology Institute, The Nethertands. In Langendorff-perfused hearts, endocardial activation during
a t r i a l driving and s t i m u l a t e d v e n t r i c u l a r p r e m a t u r e b e a t s is explored with a roving e l e c t r o d e a p p l i e d according to a p r e a r r a n g e d g r i d . Local activation is d e t e r m i n e d from uni- and bipolar leads for the m y o c a r d i u m and for the conduction s y s t e m , when p r e c e d i n g m y o c a r d i a l activity. The main divisions of the bundle b r a n c h e s and t h e i r p e r i p h e r a l r a m i f i c a t i o n s a r e identified and t h e i r a c t i v a t i o n - s e q u e n c e is eorelated with m y o c a r d i a l excitation. In the adult human heart, P u r k i n j e ' a c t i v i t y , is s p a r s e r than in the dog h e a r t . In the human left v e n t r i c l e it is r e s t r i c t e d to the middle p a r t of the i n t e r v e n t r i c u l a r septum and c l o s e l y adjacent a r e a s , whereas in the canine left v e n t r i c l e it is found diffusely. Local P u r k i n j e - t o - m y o c a r d i u m latency is 2 to 8 m s e c . in a r e a s of probable d i r e c t t r a n s m i s s i o n . In the t r a b e c u t a t i o n s e a r l y m y o c a r d i a l activation o c c u r s in v a r i o u s d i r e c t i o n s over a short d i s t a n c e . I n t e r r u p t i o n of a main conduction-pathway c a u s e s activation to be deflected via the p e r i p h e r a l P u r k i n j e plexus into the blocked a r e a . P r e m a t u r e b e a t s , initiated by m y o c a r d i a l stimulation, e n t e r rapidly into the conduction s y s t e m and a r e d i s t r i b u t e d by it in competition with m y o c a r d i a l conduction, depending on conditions of r e f r a c t o r i n e s s .
A system has been developed which employs a simple magnetically activated transmitter within the implanted pacer to noninvasively telemeter (T) data in the form of a code based on musical tones. During the last 4 yrs., 50 patients in 6 centers have had T pacers implanted. The first 20 units directly transmitted signals for cell voltage, rate, and continuity of hermetic seal. In subsequent units, the system was expanded to monitor stimulation impedance, lead/insulator integrity! power cell impedance (more informative than voltage in lithium cells), pacer refractory period, sense events, etc., the tone signals which identify normal pacer function or a specific problem (if present) can be picked up by a simple transistor radio or a specially designed receiver which precisely determines cell voltage, cell impedance, etc. The system is applicable to patient self monitoring and physician or clinic monitoring including telephone monitoring. It increases patient safety and physician confidence giving it the potential to reduce prophylactic pacemaker replacements and to limit recalls to affected units there by reducing health care costs.
A previous autopsy study demonstrated that the extent of apical involvement in anterior myocardial infarcts (AMIs) was indicated by the sum of the height of the R waves in mm minus the sum of the depth of the Q waves in mm (E R-Q) in leads V 4, V 5 and V 6. The purpose of the present collaborative study was to test the ability of E R-Q to estimate total infarct size in patients with AMIs. The hearts of 20 patients with single AMIs greater than one week old were identified at autopsy. They were cut into 6 transverse slices and infarcted regions were drawn on gross photos of each slice from microscopic sections. Outlines of the left ventricle (LV) and of the infarcted areas were entered into a computer from the photos using a sonic digitizer pen. The volumes of LV and of infarct were calculated according to a previously tested program. From the appropriate electrocardiogram, E R-Q was computed for each patient. The AMIs ranged from i to 44% of the LV (mean 23%). The E R-Q was linearly related to the percent infarction of the total LV (r = -0.94). This study demonstrates that the E R-Q in leads V4'V 6 provides a good estimate of total infarct size in human hearts with single AMIs.
February 1979
The American Journal of CARDIOLOGY
Volume 43
351
A COMPARISON OF THREE APPROACHES FOR D E T E C T I N G B O D Y SURFACE P O T E N T I A L M A P ABNORMALITIES . Hal Pham-Huy, M.Eng.; R6ginald Nadeau, MD, FACC" Ramesh Gulrajani, Ph.D.; Pierre Savard, D.Sc.A.; Fernand Roberge, Ph.D., Universit6 de Montreal, Montr6al, Canada.
MULTIPARAMETER MONITORING OF IMPLANTED CARDIAC PACEMAKERS. G. Frank O. Tyers, MD, FACC; Robert R. Brownlee, MSEE; Edward H. Williams, MD; Martin J. O'Neill, MD; Akira Nishimura, MD, FACC; Charles J. Del Marco, and Howard C. Hughes, VMD. Un. of Texas Medical Branch, Galveston, Tx.
Three approaches for detecting abnormalities in body surface potential maps (BSPMs) recorded from patients with myocardial infarction were compared. The BSPMs are generated by a minicomputer every 2.5 ms during QRS from 26 simultaneously recorded thoracic ECGs. All 3 approaches are based on detecting the deviations in certain parameters from control values, determined in our case from 40 normal subjects. The first approach emphasizes qualitative deviations in the trajectories of the BSPM extrema during QRS. This technique proved very effective on a test population of i0 normals and I0 cases of infarction, correctly classifying all normals and 9 infarcts. The second approach classifies a test subject as abnormal if any one of his 26 ECG lead waveforms deviates at any instant during QRS from the mean waveform for the particular lead plus or minus two standard deviations, these being determined from the 40 control subjects. This approach misclassified 8 of 10 normals. A final method was to obtain an instant by instant plot of the correlation coefficient (CC) between the mean BSPM during QRS for the 40 normals and that of the subject to be tested. Infarct cases were detected by at least one CC value falling below an envelope determined from the CC plots obtained by correlating the maps of all 40 normals with their own mean. Although 9 normals and 9 infarcts were correctly classified, inferior and posterior infarcts were usually only just detected with 2 or 3 CC values below the envelope. On the basis of these results the first approach is superior to the other two for detecting BSPM abnormalities.
Current pacemaker follow%up techniques to detect abnormalities and predict end of battery life (EOL) rely primarily on pacemaker rate decreases as indirect evidence of reduced battery voltage and capacity. The large number of major and minor rate changes that occur unrelated to battery voltage, the advent of rate programmability, phantom programming, and reductions in rate sensitivity with newer high current density electrodes mitigat e the usefulness of rate change for EOL prediction.
ENDOCARDIAL MAPPING HUN[AN HEARTS.
EVALUATION OF THE QRS COMPLEXES IN LEADS V4-V 6 AS INDICATORS OF THE SIZE OF ANTERIOR MYOCARDIAL INFARCTS DEFINED AT NECROPSY Raymond E. Ideker, MD, PhD, Galen S. Wagner, MD, Donald B. Hackel, MD, Sanford P. Bishop, DVM, PhD, Colin M. Bloor, MD, John T. Fallon, MD, PhD, Harry R. Phillips, MD, Keith A. Reimer, MD, PhD, Steven F. Roark, MD, William J. Rogers, MD, FACC, Robert M. Savage, MD, Ronald M. Selvester, MD. Duke Hosp., Durham NC, U. Ala. Med. Ctr., Birmingham, AL, UCSD Sch. of Med., La Jolla, CA, Mass. Gen. Hosp, Boston, MA, Rancho Los Amigos Hosp., Downey, CA.
IN I S O L A T E D
CANINE
AND
Rudolf T. van D a m , M . D . , F A C C , Dept. of Cardio[. and Clin. Physiol., University of A m s t e r d a m , and Interuniversitary Cardiology Institute, The Nethertands. In Langendorff-perfused hearts, endocardial activation during
a t r i a l driving and s t i m u l a t e d v e n t r i c u l a r p r e m a t u r e b e a t s is explored with a roving e l e c t r o d e a p p l i e d according to a p r e a r r a n g e d g r i d . Local activation is d e t e r m i n e d from uni- and bipolar leads for the m y o c a r d i u m and for the conduction s y s t e m , when p r e c e d i n g m y o c a r d i a l activity. The main divisions of the bundle b r a n c h e s and t h e i r p e r i p h e r a l r a m i f i c a t i o n s a r e identified and t h e i r a c t i v a t i o n - s e q u e n c e is eorelated with m y o c a r d i a l excitation. In the adult human heart, P u r k i n j e ' a c t i v i t y , is s p a r s e r than in the dog h e a r t . In the human left v e n t r i c l e it is r e s t r i c t e d to the middle p a r t of the i n t e r v e n t r i c u l a r septum and c l o s e l y adjacent a r e a s , whereas in the canine left v e n t r i c l e it is found diffusely. Local P u r k i n j e - t o - m y o c a r d i u m latency is 2 to 8 m s e c . in a r e a s of probable d i r e c t t r a n s m i s s i o n . In the t r a b e c u t a t i o n s e a r l y m y o c a r d i a l activation o c c u r s in v a r i o u s d i r e c t i o n s over a short d i s t a n c e . I n t e r r u p t i o n of a main conduction-pathway c a u s e s activation to be deflected via the p e r i p h e r a l P u r k i n j e plexus into the blocked a r e a . P r e m a t u r e b e a t s , initiated by m y o c a r d i a l stimulation, e n t e r rapidly into the conduction s y s t e m and a r e d i s t r i b u t e d by it in competition with m y o c a r d i a l conduction, depending on conditions of r e f r a c t o r i n e s s .
A system has been developed which employs a simple magnetically activated transmitter within the implanted pacer to noninvasively telemeter (T) data in the form of a code based on musical tones. During the last 4 yrs., 50 patients in 6 centers have had T pacers implanted. The first 20 units directly transmitted signals for cell voltage, rate, and continuity of hermetic seal. In subsequent units, the system was expanded to monitor stimulation impedance, lead/insulator integrity! power cell impedance (more informative than voltage in lithium cells), pacer refractory period, sense events, etc., the tone signals which identify normal pacer function or a specific problem (if present) can be picked up by a simple transistor radio or a specially designed receiver which precisely determines cell voltage, cell impedance, etc. The system is applicable to patient self monitoring and physician or clinic monitoring including telephone monitoring. It increases patient safety and physician confidence giving it the potential to reduce prophylactic pacemaker replacements and to limit recalls to affected units there by reducing health care costs.
A previous autopsy study demonstrated that the extent of apical involvement in anterior myocardial infarcts (AMIs) was indicated by the sum of the height of the R waves in mm minus the sum of the depth of the Q waves in mm (E R-Q) in leads V 4, V 5 and V 6. The purpose of the present collaborative study was to test the ability of E R-Q to estimate total infarct size in patients with AMIs. The hearts of 20 patients with single AMIs greater than one week old were identified at autopsy. They were cut into 6 transverse slices and infarcted regions were drawn on gross photos of each slice from microscopic sections. Outlines of the left ventricle (LV) and of the infarcted areas were entered into a computer from the photos using a sonic digitizer pen. The volumes of LV and of infarct were calculated according to a previously tested program. From the appropriate electrocardiogram, E R-Q was computed for each patient. The AMIs ranged from i to 44% of the LV (mean 23%). The E R-Q was linearly related to the percent infarction of the total LV (r = -0.94). This study demonstrates that the E R-Q in leads V4'V 6 provides a good estimate of total infarct size in human hearts with single AMIs.
February 1979
The American Journal of CARDIOLOGY
Volume 43
351