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Showing papers on "QRS complex published in 1975"


Journal ArticleDOI
TL;DR: Results from intracavitary recordings and atrial and ventricular stimulation were reviewed and found a reproducible tachycardia could be initated and terminated by appropriately timed electrical stimuli.
Abstract: To study the pathway of tachycardia in patients with the Wolff-Parkinson-White (WPW) syndrome and reciprocal tachycardias, results from intracavitary recordings and atrial and ventricular stimulation were reviewed in 71 patients with the WPW syndrome and 54 patients without pre-excitation. In all patients a reproducible tachycardia could be initated and terminated by appropriately timed electrical stimuli. The following findings were accepted as suggesting the participation of an accessory pathway in the tachycardia circuit: 1) no increase in ventriculo-atrial conduction (V-A C) time following ventricular stimuli given with increasing prematurity; 2) activation of right or left atrium (depending upon the location of the atrial end of the accessory pathway) prior to activation of atrium in the His bundle lead; 3) slowing of tachycardia following bundle branch block to the ventricle in which the accessory pathway inserts; 4) V-A C time of early stimuli on the ventricle during the tachycardia equal to or less than the V-A c time following QRS complexes during tachycardia; 5) inability to initiate tachycardia or slowing of tachycardia following the administration of drugs affecting the accessory pathway. Accepted as suggestive for atrioventricular (A-V) nodal re-entry were the following factors: 1) activation of atrium following initiation of tachycardia by a single atrial premature beat after activation of the bundle of His but before or simultaneous with ventricular activation in first and subsequent beats of tachycardia; 2) initiation of tachycardia following a gradual increase in V-A C time with the appearance of a His bundle electrogram in between the premature beat and retrograde atrial activation; 3) gradual increase in V-A C time with the appearance of a His bundle electrogram following ventricular premature beats given with increasing prematurity; 4) two-to-one block distal to the A-V node or His bundle with persistance of tachycardia. If only positive findings were accepted, 51 patients of the WPW group used their accessory pathway during tachycardia. In eight patients re-entry was confined to the A-V node. In the remaining 12 patients the mechanism was not clear. Of the patients not showing pre-excitation in A-V direction, 47 patients seemed to have their re-entry circuit in the A-V node, five patients used an accessory pathway in V-A direction, and in two patients the pathway of tachycardia could not be identified.

271 citations


Journal ArticleDOI
TL;DR: Hemodynamic correlations, made for the first time in patients, suggest that acute ventricular dilatation, possibly in combination with hypoxemia, is a causative factor of the electrocardiographic changes in acute massive or submassive pulmonary embolism.

219 citations


Journal ArticleDOI
TL;DR: Sites at which appearance of epicardial ST segment is not a reliable index of ischemic injury were associated with the development of intraventricular conduction blocks with Q to intrinsic deflection intervals exceeding 40 msec or QRS durations exceeding 65 msec; these changes wereassociated with precordial RSR′ configurations.
Abstract: Precordial electrocardiographic mapping has been proposed as a method for evaluating the extent of myocardial injury in patients with acute myocardial infarction. To assess the relationship between direct measures of myocardial cell damage and findings obtained by precordial mapping, the left anterior descending coronary artery (LAD) was occluded in dogs instrumented for simultaneous recording of epicardial and precordial electrocardiograms. The sum in millivolts of ST-segment elevation recorded from 30 electrodes placed in a Silastic grid sutured to the epicardium (EPIsigmaST) was compared to that recorded from 30 precordial electrodes (PresigmaST). While ischemic injury was: 1) maintained constant with a fixed occlusion; 2) reduced by partial reperfusion; 3) increased by addition of a second occlusion; or 4) increased repeatedly by intermittent infusions of isoproterenol, EPIsigmaST and PresigmaST were always closely correlated in each of the 16 dogs studied: r equal 0.92 plus or minus 0.01 (SEM). In seven control dogs, 30 minutes after coronary occlusion, PresigmaST had fallen to 77.4 plus or minus 6.6% of its value 15 minutes postocclusion. In seven experimental dogs, two branches of the LAD were occluded. Fifteen minutes after double occlusion, one occlusion was released; 30 min after the initial occlusion PresigmaST had fallen significantly more than control, to 43.1 plus or minus 13.1% of its value 15 minutes postocclusion. Simultaneously, epicardial sites in the reperfused area also showed normalization of ST segments and 24 hours later exhibited normal myocardial creatine phosphokinase activity and normal histologic appearance. During the same experiment, the mean precordial R wave voltage of sites with ST-segment elevations exceeding 0.15 mV 15 minutes following occlusion fell significantly (P less than 0.05) more in the control group (from 1.14 plus or minus 0.15 to 0.75 plus or minus 0.06 mV) than in the reperfused group (from 1.06 plus or minus 0.09 to 0.96 plus or minus 0.17 mV) during the ensuing 45 minutes. Thus, more rapid normalization of PresigmaST or preservation of precordial R wave voltage reflected the actual prevention of myocardial necrosis by reperfusion. These findings demonstrate the usefulness of precordial electrocardiographic mapping for evaluation changes in myocardial ischemic injury. Sites at which appearance of epicardial ST segment is not a reliable index of ischemic injury were associated with the development of intraventricular conduction blocks with Q to intrinsic deflection intervals exceeding 40 mesc or QRS durations exceeding 65 msec; these changes were associated with precordial RSR' configurations. Such sites, whether recorded from precordial or epicardial leads, should be excluded from ST-segment measurements used in the assessment of myocardial ischemia.

210 citations


Journal ArticleDOI
TL;DR: Transient hypotension, not requiring treatment, was the only side effect noted but not in the patients with supraventricular tachycardias, in whom blood pressure generally increased after reversion to sinus rhythm by verapamil.

208 citations


Journal ArticleDOI
TL;DR: It is expected that the sensitivity of the exercise ECG for detection of ischemic heart disease would be increased when heart rate dependent normal limits for ST-segment measurements are used, and different criteria should be employed for the interpretation of the ECG during and after exercise.
Abstract: The directions and magnitudes of time-normalized P, QRS, and ST vectors, and other ECG parameters were analyzed during and after multistage exercise in 56 ostensibly healthy men aged 23 to 62. By selective averaging with a digital computer system a single representative beat was obtained from each stage. Measurements were taken from this beat. During exercise, the interval between the spatial maximum of the P wave and the onset of the QRS complex decreased while the magnitude of the P wave increased. The direction of the P vectors did not change. This pattern corresponds to the electrocardiographic manifestations of predominant right atrial overload. No significant changes in the QRS duration were observed. Also the magnitude and spatial orientation of the maximum QRS vectors remained constant. The interval between the QRS onset and the maximum spatial magnitude of the T wave shortened. The terminal QRS vectors and the ST vectors gradually shifted toward the right, and superiorly. The T magnitude lessened during exercise. In the first minute of the recovery period the P and T magnitudes markedly increased. Afterward all measurements gradually returned to the resting level. Mechanisms which may explain the observed ECG changes during and after exercise are discussed, including changes in the blood conductivity and intracardiac blood volume. Age did not contribute to the variance of the ECG measurements, but a significant reduction of this variance could be otained in some ST-segment measurements by relating them to heart rate with linear regression equations (P less than or equal to 0.05). Therefore it is expected that the sensitivity of the exercise ECG for detection of ischemic heart disease would be increased when heart rate dependent normal limits for ST-segment measurements are used. Different criteria should be employed for the interpretation of the ECG during and after exercise.

124 citations


Journal ArticleDOI
TL;DR: The present study shows that lidocaine has different effects in infarcted and normal zones of the heart, and has local anesthetic actions which might explain its effectiveness in curtailing ventricular arrhythmias after acute myocardial infarction.
Abstract: Lidocaine was administered as a rapid intravenous bolus injection followed by a constant-rate intravenous infusion to nine dogs with 2-hour-old myocardial infarctions. Bipolar electrograms were recorded from and effective refractory periods were determined in the infarcted and normal zones of the heart. Intervals (Q-EG) were measured from the onset of the QRS complex in a standard electrocardiogram limb lead to the major deflection of the recorded electrograms from the normal and infarcted zones. QRS duration and serum lidocaine concentration were also determined. At serum concentrations considered to be therapeutic, lidocaine prolonged the Q-EG intervals in the infarcted zones of the heart 17-26% at peak effect (P less than 0.01), but it had no effect on the Q-EG intervals in the normal zone except for a slight (1.5%) prolongation shortly after the initial intravenous bolus injection. Lidocaine also had no effect on QRS duration. Similarly, lidocaine prolonged the effective refractory period of the infarcted zone 23% (P less than 0.01) at peak effect but had no effect on the effective refractory period of the normal zone. Prior to lidocaine administration, the mean effective refractory period of the normal zone was 26 msec longer than that of the infarcted zone, but at peak drug effect the disparity in refractoriness was reduced to 1 msec. The present study thus shows that lidocaine has different effects in infarcted and normal zones of the heart. In delaying activation and prolonging the effective refractory period of the infarcted zone of the heart, lidocaine has local anesthetic actions which might explain its effectiveness in curtailing ventricular arrhythmias after acute myocardial infarction.

117 citations


Journal ArticleDOI
TL;DR: A prolonged H-V interval was often associated with serious myocardial dysfunction and a high mortality rate and the risk of progression of conduction disease was slight with either a prolonged or a normal H- V interval during this relatively short follow-up period.
Abstract: Electrophysiologic studies were performed in 119 adults with chronic bifascicular block manifested by right bundle branch block and left anterior hemiblock. The H-V interval was normal in 86 patients and prolonged in 33. The following clinical variables were more frequent (P less than 0.05) in patients with a prolonged H-V interval: cardiac third sound, mitral systolic murmur, cardiomegaly on chest roentgenogram, congestive heart failure and cardiac functional class III or IV (New York Heart Association criteria). The following differences in the electrocardiographic and electrophysiologic findings were found: Patients with a prolonged H-V interaval had a longer mean P-R interval, QRS duration and A-H interval (P less 0.02). All patients were followed up prospectively in a cardiac conduction disease clinic after initial evaluation. The mean follow-up periods were (mean plus or minus standard error of the mean) 514 plus or minus 49 and 563 plus or minus 34 days for the patients with a prolonged and normal H-V interval, respectively. Progression of conduction disease occurred in three patients (4 percent) with a normal H-V interval and in four (12 percent) with a prolonged interval. The cumulative 3 year mortality rate for the entire group was 25 percent. The patients with a prolonged H-V interval had a higher cumulative 2 year mortality rate than those with a normal H-V interval but the difference was not statistically significant. In summary, a prolonged H-V interval was often associated with serious myocardial dysfunction and a high mortality rate. The risk of progression of conduction disease was slight with either a prolonged or a normal H-V interval during this relatively short follow-up period.

98 citations


Journal Article
TL;DR: Two cases suggest the following conclusions: (1) dual A-V nodal pathways may allow the occurrence of double antegrade conduction of one P; (2) the atria are not necessary for A-v nodal circus movements in "dual pathway" A- V nodal reentrant PSVT.
Abstract: Electrophysiological studies with extrastimulus technique demonstrated evidence of dual A-V pathways in two patients with paroxysmal supraventricular tachycardia (PSVT). In case one, the second P of paced Wenckebach sequences was followed by two conducted QRS complexes without an intervening P wave. The A-H of the first and second QRS were consistent with the fast and slow pathway conduction times. The second QRS was followed by an atrial echo and PSVT, suggesting that the first pathway was available for retrograde propagation following the second QRS. In case two, PSVT was induced with atrial extrastimulus, followed by development of A-V dissociation. The two cases suggest the following conclusions: (1) dual A-V nodal pathways may allow the occurrence of double antegrade conduction of one P; (2) the atria are not necessary for A-V nodal circus movements in "dual pathway" A-V nodal reentrant PSVT.

97 citations


Journal ArticleDOI
TL;DR: The epicardial activation sequence of 34 patients with the Wolff-Parkinson-White syndrome was determined and the polarity of the delta wave and maximum QRS forces in precordial lead V1 were discordant in a significant number of patients, pointing to probable short-comings of a classification based upon the latter.
Abstract: The epicardial activation sequence of 34 patients with the Wolff-Parkinson-White syndrome was determined. Epicardial pre-excitation occurred at a spectrum of sites over either the free wall of the left or right ventricle or in a paraseptal region, always adjacent to the atrioventricular rings. The site of pre-excitation was related to the spatial position of the 10 msec vector of the vectorcardiogram (VCG) in 15 patients and the 20 msec vector of the electrocardiogram (ECG) in 29 patients with a single accessory pathway. All patients whose 20 msec vector (ECG) was directed to the right had accessory pathways which caused epicardial breakthrough over the free wall of the left ventricle. When the 20 msec vector (ECG) was to the left and inferior, epicardial pre-excitation was over either the right ventricular free wall or in the region of the pulmonary outflow tract. Superior location of the initial forces, especially the 10 msec vector (VCG), strongly suggested the presence of a septal bypass tract. The polarity of the delta wave and maximum QRS forces in precordial lead V1 were discordant in a significant number of patients, pointing to probable shortcomings of a classification based upon the latter.

91 citations


Journal ArticleDOI
TL;DR: Electrophysiologic characteristics of five patients with Ebstein's anomaly of the tricuspid valve were defined with studies using luminal intracardiac electrode catheters, finding the ARV was particularly irritable, and ventricular fibrillation was produced in two patients during catheter manipulation in this area.
Abstract: Electrophysiologic characteristics of five patients with Ebstein's anomaly of the tricuspid valve were defined with studies using luminal intracardiac electrode catheters. The diagnosis was made in each case from clinical data and confirmed at cardiac catheterization by the presence of an atrialized right ventricular chamber with atrial mechanical activity and ventricular electrical activity. In three cases intra-right atrial conduction was prolonged (P-A intervals of 50, 50, and 65 msec), a finding which reflected the presence of a characteristically large right atrium. The bundle of His electrogram was recorded in its usual anatomical location. Atrioventricular nodal conduction was prolonged in only one case. Intra-His delay was observed in two cases (bundle of His duration of 30 and 30 msec). Infranodal conduction was prolonged in four cases with H-V intervals of 60, 65, 65, and 80 msec. The anatomical abnormalities were least severe in the only patient with a normal H-V interval (50 msec). The prolonged H-V interval was thought to result from stretching of the conduction system over the atrialized right ventricle (ARV). The late depolarization during the splintered R' of the electrocardiogram found during intracardiac mapping of the ARV in three patients confirms the theory that the ARV produces the "second QRS" typically seen in this anomaly. The ARV was particularly irritable, and ventricular fibrillation was produced in two patients during catheter manipulation in this area. In one case the ARV had a shorter refractory period than the body of the right ventricle. Re-entrant supraventricular tachycardia was induced in the only patient with Wolff-Parkinson-White syndrome. In addition to the previously recognized electrophysiologic features reconfirmed here, patients with Ebstein's anomaly of the tricuspid valve usually have: normal position of the bundle of His, prolonged intra- right atrial conduction, prolonged infranodal conduction, and irritable ARV with delayed activation.

91 citations


Journal ArticleDOI
TL;DR: The study shows that the basic prerequisites for re-entry do exist during the early period following occlusion of a major coronary artery and can explain the malignant phase of ventricular arrhythmias.
Abstract: In 20 anesthetized opened-chest dogs, plunge wire and electrode catheter recordings of the this bundle electrogram which also showed septal activation, were monitored before and after ligation of the anterior septal artery. The average time to onset of ventricular tachycardia after ligation was 5-1/2 min. The evolution of the arrhythmia was temporally related to progressive fragmentation and delay of the septal potential, resulting in a marked increase in total ventricular activation time (up to 335 msec). In six experiments the fragmented, delayed septal depolarization was inscribed well beyond the T wave of the surface QRS prior to the onset of arrhythmias. Various conduction disorders involving the ischemic septal myocardium were observed which closely correlated to the patterns of conduction disorder in the ischemic proximal His-Purkinje system. First degree block, 2 degree block of the Mobitz II and Wenckebach types, higher degree block and paroxysmal complete block occurred. The onset of the arrhythmia was characteristically associated with a Wenckebach pattern of conduction delay of a part of the septal deflection. Conduction disorders of the ischemic myocardium were tachycardia-dependent. Bradycardia resulted in recovery of form, duration, and timing of the septal potential with the coincident disappearance of ventricular arrhythmias. The study shows that the basic prerequisites for re-entry do exist during the early period following occlusion of a major coronary artery and can explain the malignant phase of ventricular arrhythmias. Similar disorders in man may be detected by intracardiac electrode catheter recordings.

Journal ArticleDOI
TL;DR: The findings suggest that treatment directed towards stabilsing the matabolism of the ischaemic myocardium can be of therapeutic value and lead to fewer serious ventricular arrhythmias.

Journal Article
TL;DR: The validity of this improved radionuclidic technique in the atraumatic quantification of ventricular function is demonstrated and its usefulness in a variety of clinical conditions is suggested.
Abstract: An improved, noninvasive, radionuclidic, gated blood-pool imaging technique was developed for clinical analysis of regional contraction abnormalities of the left ventricle and determination of ejection fraction. The principal innovations include high-resolution collimation, higher information density, improved method for dynamic aortic-mitral-diaphragmatic border delineation, accurate selection of the end-systolic gating interval through the use of the phonocardiogram, and accurate end-diastole by on-line gating immediately following the electrocardiographic QRS. The results of scintigraphic studies using /sup 99m/Tc-human serum albumin or /sup 99m/Tc-autologous erythrocytes as tracer were compared with selective radiopaque cineangiographic findings in 27 patients with cardiac disease; excellent correlations of ejection fractions and abnormal contraction patterns were demonstrated. In addition, the clinical usefulness in evaluating ventricular performance was demonstrated in 79 patients with acute and chronic coronary artery disease. (auth)

Journal ArticleDOI
TL;DR: Epicardial mapping provides a method for defining antegrade and retrograde sites of pre-excitation and can be applied to localization of the site of origin of atrial or ventricular dysrhythmias, localization of myocardial ischemia and infarction, as well as to differentiate between epicardial delays due to conduction delay and those caused by intramural myocardIAL delay.
Abstract: The syndrome of Wolff-Parkinson-White (WPW) is classically defined by an electrocardiogram with a short PR interval, a prolonged QRS complex that begins with an abnormal initial force known as the delta wave, and is seen in patients who are predisposed to tachyarrhythmias. 1 Figure 1 shows the ECG of WPW compared with a normal ECG. The PR interval is short because the QRS (the delta wave) begins abnormally early in relationship to the end of the P wave. Thus, the PR interval is shortened to the same extent that the QRS is prolonged. The diagram on the right depicts atrial activation in phase 1. Phase 2 demonstrates premature ventricular excitation (preexcitation) over an accessory atrioventricular connection that conducts without the delay exhibited by the atrioventricular node. The anomalous, premature depolarization is indicated by the darker grain pattern in the heart and in the ECG. During phase 3, the ventricle is

Journal ArticleDOI
TL;DR: A special program has been developed for on-line processing of orthogonal electrocardiograms during exercise with a small computer system that resulted in a lower measurement error than other methods for waveform analysis.

Journal ArticleDOI
TL;DR: In this paper, the pathologic findings in a 54 year old woman with intermittent preexcitation who died of carcinoma of the breast were discussed. But the case was not classified into any known variety of preexcitations.
Abstract: This report concerns pathologic findings in a 54 year old woman with intermittent preexcitation who died of carcinoma of the breast. Electrocardiograms revealed predominantly normal sinus rhythm with a normal P-R interval and narrow QRS complex. Episodes of sinus rhythm, short P-R interval and QRS widening (with delta wave) were also recorded. During preexcitation QS complexes were noted in leads II, III, aVF, V1 and V4 to V6. Delta waves were negative in leads II, III, aVF and V1 isoelectric in leads V4 to V6 and positive only in leads I, aVL, V2 and V3. This case thus defies classification into any known variety of preexcitation. Complete serial sections, cut through the entire conduction system and both atrioventricular (A-V) rims, totaled 18,600 sections. These revealed no bundle of Kent. Instead, Mahaim fibers histologically identified as His bundle tissue gave off from the A-V bundle to both the right and the left sides of the septum associated with the normal fibers of James. This case reveals that (1) fibers of James can bypass the A-V node, (2) fibers of Mahaim can conduct, and (3) there are types of preexcitation in addition to types A and B.

Journal ArticleDOI
TL;DR: A positive correlation was found between presence or absence of fibrosis and duration of the QRS complex, but this correlation appeared to be spurious and due to the tendency of fibrosed hearts to be heavier than those with normal myocardium.

Journal ArticleDOI
TL;DR: The data indicate that endocardial activation changes can be evaluated in the catheterization laboratory, that right ventricular conduction becomes slower in RBBB as a direct function of total QRS and that left ventricular Conduction may be affected when R BBB develops.
Abstract: The sequence of intraventricular conduction has been studied in a total of 60 patients, 38 of whom had normal QRS morphology and 37 of whom had right bundle branch block (RBBB) either present continuously or produced as functional aberrant RBBB by the introduction of atrial premature depolarizations or by rapid atrial pacing. Activation times were measured by intracardiac electrode catheters positioned at the right ventricular inflow tract (RVIT), right ventricular apex (RVA), right ventricular outflow tract (RVOT), left ventricular apex (LVA) and left ventricular outflow tract (LVOT). The activation after beginning of QRS in milliseconds plus or minus 1 SD and the number of patients studied at each location were: RVIT--normal 23 plus or minus 13 (15 patients); RVIT-RBBB 49 plus or minus 16 (15 patients); RVA--normal 18 plus or minus 9 (28 patients); RVA-RBBB 54 plus or minus 16 (30 patients); RVOT--normal 40 plus or minus 10 (28 patients); RVOT-RBBB 78 plus or minus 21 (30 patients);LVA--normal 9 plus or minus 9 (18 patients); LVA-RBBB 6 plus or minus 10 (10 patients); LVOT--normal 45 plus or minus 13 (10 patients); LVOT-RBBB 32 plus or minus 9 (7 patients). Significant differences observed were: RVA-normal versus RVA-RBBB P smaller than 0.001; RVOT-RBBB P smaller than 0.001; RVA-normal versus LVA-normal P smaller than 0.005; LVA-normal versus LVA-RBBB NS, LVOT-normal versus LVOT-RBBB P smaller than 0.05. The LVOT change was unexpected and suggests changes in left ventricular depolarization may occur when right bundle branch block develops. In patients with RBBB the activation of the RVA (r equals 0.82) and of the RVOT (r equals 0.68) was directly related to the duration of QRS. Changes in activation time when RBBB was induced by rapid atrial pacing or by introduction of atrial premature depolarizations were: RVA (7 patients) 19 plus or minus 11 to 56 plus or minus 16 (P smaller than 0.001); RVOT (9 patients) 41 plus or minus 10 to 77 plus or minus 22 (P SMALLER THAN 0.001); LVA (5 patients) and LVOT (2 patients), small insignigicant changes. These data indicate that endocardial activation changes can be evaluated in the catheterization laboratory, that right ventricular conduction becomes slower in RBBB as a direct function of total QRS and that left ventricular conduction may be affected when RBBB develops.

Journal ArticleDOI
TL;DR: An improved technique for identification, diagnosis and quantification of arrhythmias during rest or ambulatory electrocardiographic recording is described, with simultaneous plotting of the R-R interval and the QRS duration and QRS vector measurement of each beat versus time.
Abstract: An improved technique for identification, diagnosis and quantification of arrhythmias during rest or ambulatory electrocardiographic recording is described. With simultaneous plotting of the R-R interval and the QRS duration and QRS vector measurement of each beat versus time, all periods of arrhythmias or abnormal complexes can be identified and characterized. Analog electrocardiographic samplings are used to confirm the diagnosis of the arrhythmia and to exclude artifact. The availability of a permanent record for the characterization of each QRS complex enables the physician to check the technician's analysis of the recording and to relate all events to the patient's heart rate and clinical symptoms. This technique also provides data for quantification of ventricular arrhythmias.

Journal ArticleDOI
01 Sep 1975-Heart
TL;DR: Maximal exercise testing of patients suspected of variant angina provides important diagnostic information in many patients, but the risks of potentially lethal arrhythmias should be considered and resuscitation facilities should always be immediately available.
Abstract: Six patients with spontaneous angina associated with transient ST segment elevation had a multistate maximal exercise (bicycle) test. In 5 patients, typical electrocardiographic changes were recorded during exercise, namely ST segment elevation often accompanied by an increase in the voltage of the R wave and a widening of the QRS complex. Four of these patients developed severe rhythm disturbances: ventricular tachycardia (2 cases) and ventricular flutter (1 case) were the reason for early interruption of the test in 3 patients, while 1 patient had a short run of ventricular tachycardia after exercise. These rhythm disturbances which spontaneously regressed in all cases were consistently preceded by obvious ST elevation and in 2 patients were attended by slight chest discomfort. Maximal exercise testing of patients suspected of variant angina provides important diagnostic information in many patients, but the risks of potentially lethal arrhythmias should be considered and resuscitation facilities should always be immediately available.

Journal ArticleDOI
TL;DR: It is concluded that the rsR' or rSr' pattern in ASD is likely to be a manifestation of right ventricular overload rather than a true conduction delay in the RBB.

Journal ArticleDOI
TL;DR: These pathways of ventricular activation may be explained by the rather complete penetration of Purkinje fibers through both ventricular free-walls in a manner similar to that of ungulates but different from carnivores and primates.

Journal ArticleDOI
01 Apr 1975-Chest
TL;DR: The atropine test was found to be an efficient and simple diagnostic aid in cases of brain death and electrocardiographic changes, including progressive depression of sinus activity and atrial fibrillation, were found.

Journal ArticleDOI
TL;DR: A characteristic conduction abnormality is identified that is compatible with a partial A-V nodal bypass or dual A-v nodal conduction pathways and may aid understanding of the clinical significance of the scalar electrocardiogram.
Abstract: To evaluate the refractory periods of the atrioventricular (A-V) conducting system in patients with a short P-R interval and normal QRS complex, 57 patients with a P-R interval of 110 to 280 msec were studied with His bundle recording and premature atrial stimulation at similar cycle lengths of 660 to 720 msec. In 13 patients with a short P-R interval (120 msec or less) the mean value for the functional refractory period of the A-V node was 368 ± 36 msec (standard deviation), which was significantly lower ( P P The results identify a characteristic conduction abnormality that is compatible with a partial A-V nodal bypass or dual A-V nodal conduction pathways. The relation between the duration of the P-R interval and the refractory period may aid understanding of the clinical significance of the scalar electrocardiogram.

Journal ArticleDOI
TL;DR: The results of this study suggest that there are qualitative differences between the causative mechanisms and clinical features of left axis deviation and those of left anterior hemiblock.
Abstract: Electrocardiographic patterns of left axis deviation and left anterior hemiblock, defined by a frontal plane QRS axis of −30 ° to −44 ° and −45 ° to −90 °, respectively, with normal QRS duration, were found to be fairly common (2.6 and 1.5 percent, respectively) in a community population of 8,000 Japanese-American men aged 45 to 69 years. More than 60 percent of men with these electrocardiographic patterns had no other cardiovascular abnormalities, and the incidence of fatal or nonfatal coronary heart disease and stroke in this group during observation periods of 3 to 6 years was not significantly different from that of control normal men. A significant association was found between these electrocardiographic patterns and the prevalence of hypertension, myocardial infarction and stroke. However, the association of myocardial infarction with left anterior hemiblock appeared to be coincidental and was attributed largely to the similarity of the electrocardiographic manifestations of left anterior hemiblock and inferior wall myocardial infarction. Men with left axis deviation were fatter and had higher blood pressure than the control population. No such difference could be demonstrated for men with left anterior hemiblock although this group was significantly older than control subjects and men with left axis deviation. The results of our study suggest that there are qualitative differences between the causative mechanisms and clinical features of left axis deviation and those of left anterior hemiblock.

Journal ArticleDOI
TL;DR: Observations in patients with inferior wall myocardial infarction suggest that ST-VM and ST-VD can be serially followed in such patients, and estimation of the magnitude and direction of the S-T vector is a simple alternative to standard precordial S- T segment mapping.
Abstract: Precordial S-T segment mapping has been used to evaluate the extent of ischemie injury in patients with acute myocardial infarction. Because precordial S-T segment mapping is time-consuming and is limited to patients with anterior wall myocardial infarction, we evaluated the possibility of using the magnitude (ST-VM) and direction (ST-VD) of the S-T vector, derived from X, Y and Z leads of the Frank vector system, as a substitute for the precordial S-T segment mapping technique. Precordial S-T segment mapping and Frank system vectorcardiograms were simultaneously obtained in three groups: (1) nine normal subjects; (2) nine patients with persistent S-T segment elevation 2 to 15 months after acute anterior myocardial infarction; and (3) nine patients with acute anterior myocardial infarction studied on 41 occasions. For both systems the S-T segments were analyzed 20 and 60 msec after completion of inscription of the QRS complex. The sum of the S-T segment elevations for the 35 sites (∑ST) and the number of sites (NST) in which S-T segment elevations exceeded 0.1 mv were computed for the precordial S-T maps. The ST-VM and ST-VD were calculated by standard formulas from X, Y and Z lead tracings of the Frank vector system. Good correlations were observed between: ST-VM and ∑ST (r = + 0.818 and + 0.791 at 20 and 60 msec, respectively, P

Journal ArticleDOI
TL;DR: Intracardiac electrophysiological studies were performed in two patients with Wolff-Parkinson-White (WPW) syndrome and the existence of a congenitally short anterosuperior division of the left bundle could be excluded.
Abstract: Intracardiac electrophysiological studies were performed in two patients with Wolff-Parkinson-White (WPW) syndrome. Atrial pacing at increasing rates or shorter coupling intervals produced inscription of the forward His bundle deflection at progressively longer intervals after the onset of ventricular depolarization. There was an associated increase in QRS duration without any change in the P-R (or St-V) interval. This response was consistent with a Kent bundle. Case 1 also had a short A-H interval which did not show the expected prolongation with stimulation at progressively faster rates. This suggested the presence of a James bundle in addition to the Kent bundle. In case 2 beats conducted exclusively through the atrioventricular (A-V) node had a short H-V interval but a delta wave was not inscribed. Absence of an initial slurring was attributed to the existence of an infra-His bundle bypass of the Mahaim type causing only slight pre-excitation, which was not of sufficient magnitude to be recorded by body surface leads. However, the existence of a congenitally short anterosuperior division of the left bundle could nt be excluded.

Journal Article
TL;DR: A case of permanent atrial standstill with syncopal attacks, in a patient with chronic Chagas' Heart Disease, based upon the conventional and intracavity electrocardiographic tracings in addition to phonomecanographic and hemodynamic data.
Abstract: The authors present a case of permanent atrial standstill with syncopal attacks, in a patient with chronic Chagas' Heart Disease. The recognition of this dysrhythmia was based upon the conventional and intracavity electrocardiographic tracings in addition to phonomecanographic and hemodynamic data. The recording of the His Bundle electrogram demonstrated the absence of atrial activity, with the His potential preceding all ventricular complexes and an advanced conduction defect distal to the bundle of His. A diffuse type of atrial involvement was suggested by the lack of response to pacemaker stimulation. An increase in ventricular rate following intravenous atropine administration, led to the diagnosis of an a-v junctional rhythm with a widened QRS complex due to an associated right bundle branch block. Following the implantation of an epicardial ventricular pacemaker, the patient became completely asymptomatic despite the persistence of electrical and mechanical atrial standstill.

Journal ArticleDOI
TL;DR: A family of 28 individuals spanning four generations was investigated because of a finding of complete heart block in five members and the existence of a low degree of atrioventricular (A-V) heartBlock in a sixth member, probably due to an autosomal dominant trait.
Abstract: A family of 28 individuals spanning four generations was investigated because of a finding of complete heart block in five members and the existence of a low degree of atrioventricular (A-V) heart block in a sixth member. The disorder was characterized by 1) adult onset in all, 2) complete A-V heart block in five and first degree A-V heart block in one, 3) sinus bradycardia in three, 4) atrial fibrillation in five, 5) abnormal QRS complex in five, 6) ventricular tachycardia in three, 7) left ventricular enlargement in all, and 8) mitral insufficiency in five. Proximal location of the A-V heart block was suggested by the fact that atropine caused acceleration of the ventricular rate and by the presence of a His bundle potential preceding the QRS complexes. Involvement of the distal conducting system was indicated by the widened QRS complex and a prolonged H-V interval. Pathologic examination in one case showed extensive sinus node fibrosis and interruption of the A-V node-His bundle connection. This disorder is probably due to an autosomal dominant trait.

Journal ArticleDOI
TL;DR: The hypothesis that cross-fiber activation enhances notching was confirmed and notches versus the angle formed between fiber direction and orientation of the direction of travel were shown to be related.
Abstract: High frequency notching of the QRS complex is associated with transmural infarction, cardiomyopathies, and ventricular hypertrophy from any cause. The mechanism producing notching is unknown; but the presence of a discrete anatomic lesion is not an essential feature. The hypothesis that notching was produced by activation across, rather than along, myocardial fibers was investigated by stimulation at 12 points around a clock electrode attached to the epicardium while mapping isoschronous lines in the area activated. All fibers at the subendocardial layer beneath the clock electrode were ligated by a pursestring suture. Propagation direction, as measured by isoschronous maps, produced more notched QRS compleses when the path was across, rather than paralled with, the myocardial fibers. Using grouped data and a 5 times 6 table, notches versus the angle formed between fiber direction and orientation of the direction of travel were shown to be related (P less than 0.001). The hypothesis that cross-fiber activation enhances notching was confirmed. retrograde activation did not increase notching nor did ligation of subendocardial fibers.