Prevalence of patent foramen ovale in patients with acute myocardial infarction and angiographically normal coronary arteries.
Explore the source record for details and available documents.
Adult↗
Biomedical subjects
A H Shandling
Publications and source records attributed to A H Shandling.
Hyperbaric oxygen and thrombolysis in myocardial infarction: the 'HOT MI' randomized multicenter study.
In a previous pilot study, we demonstrated that adjunctive treatment with hyperbaric oxygen (HBO) appears to be feasible and safe in patients with acute myocardial infarction (AMI) and may result in an attenuated rise in creatine phosphokinase (CPK), more rapid resolution of pain and ST changes. This randomized multicenter trial was organized to further assess the safety and feasibility of this treatment in human subjects. Patients with an AMI treated with recombinant tissue plasminogen activator (rTPA) or streptokinase (STK), were randomized to treatment with HBO combined with either rTPA or STK, or rTPA or STK alone. An analysis included 112 patients, 66 of whom had inferior AMIs (p = NS). The remainder of the patients had anterior AMIs. The mean CPK at 12 and 24 h was reduced in the HBO patients by approximately 7.5% (p = NS). Time to pain relief was shorter in the HBO group. There were 2 deaths in the control and 1 in those treated with HBO. The left ventricle ejection fraction (LVEF) on discharge was 51.7% in the HBO group as compared to 48.4% in the controls (p = NS). The LVEF of the controls was 43.4 as compared to 47.6 for those treated, approximately 10% better (no significant difference). Treatment with HBO in combination with thrombolysis appears to be feasible and safe for patients with AMI and may result in an attenuated CPK rise, more rapid resolution of pain and improved ejection fractions. More studies are needed to assess the benefits of this treatment.
Adolescent↗
Hyperbaric oxygen and thrombolysis in myocardial infarction: the "HOT MI" pilot study.
Hyperbaric oxygen treatment (HBO) in combination with thrombolysis has been demonstrated to salvage myocardium in acute myocardial infarction in the animal model. Therefore a randomized pilot trial was undertaken to assess the safety and feasibility of this treatment in human beings. Patients with an acute myocardial infarction (AMI) who received recombinant tissue plasminogen activator (rTPA) were randomized to treatment with HBO combined with rTPA or rTPA alone. Sixty-six patients were included for analysis. Forty-three patients had inferior AMIs (difference not significant) and the remainder had anterior AMIs. The mean creatine phosphokinase level at 12 and 24 hours was reduced in the patients given HBO by approximately 35% (p = 0.03). Time to pain relief and ST segment resolution was shorter in the group given HBO. There were two deaths in the control group and none in those treated with HBO. The ejection fraction on discharge was 52.4% in the group given HBO compared with 47.3% in the control group (difference not significant). Adjunctive treatment with HBO appears to be a feasible and safe treatment for AMI and may result in an attenuated rise in creatine phosphokinase levels and more rapid resolution of pain and ST segment changes.
Adolescent↗
Diagnostic accuracy of predicting coronary artery disease related to patients' characteristics.
Patients' demographic and clinical characteristics may affect diagnostic accuracy of cardiologists. We asked a group of experienced cardiologists from three institutions to estimate the pretest probability of coronary artery disease in 257 patients referred for diagnostic coronary angiography and with no history of previous myocardial infarction nor valvular heart disease. Physicians pretest estimates were compared with the diagnostic findings of coronary angiography. We tested the influence of five variables on the accuracy of the pretest estimates: age, sex, chest pain characteristics, rest electrocardiogram and electrocardiographic exercise test result. Cardiologists tended to overestimate the presence of coronary artery disease and this tendency was particularly remarkable in the group of patients showing a negative exercise test. Pretest diagnostic accuracy was 0.72 when the test result was negative and 0.85 when the test result was positive (95% confidence interval of the difference 0.03 to 0.23; p < 0.001). The diagnosis of coronary artery disease was also more accurate for male than for female patients (0.81 vs 0.70; 95% confidence interval of the difference 0.02 to 0.21; p < 0.02). Characteristics of chest pain, age and rest electrocardiogram did not affect the level of pretest diagnostic accuracy. Cardiologists should be cognizant of correctly interpreting a negative exercise test and the clinical data of female patients; in both cases, they should move circumspect of the diagnosis of coronary artery disease.
Age Factors↗
Analysis of the signal-averaged P-wave duration in patients with percutaneous coronary angioplasty-induced myocardial ischemia.
To assess the impact of angioplasty-induced myocardial ischemia on the duration of the surface P wave, patients undergoing elective angioplasty of isolated lesion in the left anterior descending, circumflex or right coronary arteries were monitored with a 3-channel electrocardiographic Holter system. The leads used were modified bipolar chest leads V5, aVF and V2 (CM-V5, CS-aVF and CM-V2). After echocardiographic signal-averaging, the earliest onset and the latest offset of the P wave were identified in all of the above time-aligned signal-averaged leads, and the composite maximal P duration was measured under 10 x magnification. The maximal ST-segment shift during balloon inflation was also measured in all of the above leads at 60 ms after the J point. In the study group comprising 47 patients, the mean signal-averaged P-wave duration was 125.0 +/- 16 ms at baseline versus 130.0 +/- 15 ms during balloon inflation, p less than 0.005. In the left anterior descending coronary artery group (n = 23), the mean signal-averaged P-wave duration was 122.4 +/- 17 ms and 131.3 +/- 16 ms during balloon inflation, p less than 0.005). In the group with a right coronary artery lesion (n = 18), the values were 127.3 +/- 14 ms and 128.4 +/- 13 ms respectively (p = not significant). Significant increases in the P-wave duration were found to occur in groups both with (n = 34) and without (n = 13) ST-segment shift greater than or equal to 1 mm (both p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
Algorithms↗
The effect of chronic atrial overdrive suppression pacing on the incidence of supraventricular tachyarrhythmias.
Chronic overdrive suppression pacing has been suggested as an effective adjunctive method for reducing the incidence of cardiac tachyarrhythmias. Documentation of effectiveness during prolonged monitoring is lacking, however. To assess more accurately the long-term utility of this treatment modality for medically refractory supraventricular tachyarrhythmias (SVTs), 10 patients with atrially implanted Intermedics Intertach pacemakers were randomly assigned to either a low or a high bradycardia (back-up) pacing rate. SVT counts were performed during matching follow-up periods both at the initial rate and after rate crossover. The primary antitachycardia modality of this pacemaker (P mod) provides burst pacing to terminate tachycardia episodes, and P mod counters were utilized to quantitate SVT episodes. Tachycardia termination algorithms were programmed to "no restart" and were not changed during the study. The P mod use counter, therefore, reflected the number of discrete episodes of SVTs. Pacemaker implantation diagnoses include atrial flutter, concealed bypass tract, AV nodal reentry, intraatrial reentry, and Wolff-Parkinson-White associated tachycardia. Patient age was 59 +/- 18 yrs. The average pacemaker back-up low rate was 45.7 +/- 4 versus a back-up high rate of 85.1 +/- 2 beats/min. Follow-up was for 57.4 days +/- 33 days at the low rate and 57.3 days +/- 34 days at the high rate (r = 0.99). There was no difference in SVT incidence with a P mod usage of 98.4 +/- 106 at the low rate and 100.8 +/- 94 at the high rate (p = NS). In this blinded, randomized cross-over trial, chronic atrial overdrive suppression pacing did not reduce the overall incidence of SVT episodes during prolonged monitoring.
Activities of Daily Living↗
Efficacy of three-channel ambulatory electrocardiographic monitoring for the detection of myocardial ischemia.
The recognition of silent myocardial ischemia (SMI) has been demonstrated to have important clinical relevance. Two-channel ambulatory (Holter) electrocardiographic recording is a commonly utilized method for detecting transient electrocardiographic ST segment changes representative of SMI. It has been suggested that the analysis of two channels alone may not adequately detect SMI. We therefore evaluated the diagnostic yield of three channels using a three-channel electrocardiographic monitoring device in 46 consecutive patients (age 61 +/- 9 years) undergoing percutaneous transluminal coronary angioplasty of an isolated single-vessel stenosis. Modified bipolar chest leads V2, V5, and AVF (CM-V2, CM-V5, and CS-AVF) were utilized for analysis. The percent detection of ST segment changes from various combinations of two-lead recordings were compared to the total three leads, and an absolute transient ST segment shift (STSS) of greater than or equal to 1 mm during balloon inflation was considered as evidence of myocardial ischemia. One patient was excluded because of the need for ventricular pacing during balloon inflation. A total of 33 of 45 patients had STSS in all three leads (percent detection = 73%), while 32 (71%) had STSS in the two-lead grouping with the highest diagnostic yield (CM-V2/CM-V5; p = ns). Of the various two-lead combinations studied, leads CM-V2 and CM-V5 provided the best lead set overall for the detection of ischemic STSS. Three-channel ambulatory electrocardiographic recording only marginally improves upon the detection of ischemia when compared with standard (CM-V2/CM-V5 or CM-V5/CS-AVF) two-channel ambulatory electrocardiographic recordings.
Angioplasty, Balloon, Coronary↗
Dacron-woven pacemaker pouch. Influence on long-term pacemaker mobility.
Pacemaker migration can interfere with correct pacing system function and patient comfort. A Dacron pouch has been developed which may prevent these problems. To assess the efficacy of the pouch, we measured various factors of pacemaker mobility in 100 patients after long-term follow-up. The patients were divided into three groups on the basis of their dictated operative reports: group 1, no pouch or anchoring stitch; group 2, pouch only; group 3, anchoring stitch to pacemaker header or pouch. The average age of the study population was 74.3 +/- 11 years. Total follow-up time was 42 +/- 28 months (group I, 53 +/- 32 months; group 2, 36 +/- 23 months; group 3, 34 +/- 25 months). There were no significant differences when pacemakers were measured for movement in the inferosuperior and lateromedial directions, nor was there any difference in the distance between the incision scar and the pacemaker header in any group. There was a significant difference between group 1 and groups 2 and 3 when the degree of tilt of the pacemaker off the chest wall was compared. This was 46 degrees +/- 34 degrees for group 1 and 27 degrees +/- 26 degrees and 26 degrees +/- 27 degrees for groups 2 and 3, respectively (p less than 0.02 for both). These data suggest that the Dacron pouch does not restrict pacemaker mobility parallel to the chest wall during long-term follow-up but does reduce the angle to which the pacemaker can be tilted relative to the chest wall.
Aged↗
Alternate methods for the determination of atrial capture threshold utilizing the telemetered intracardiac electrogram.
Periodic determination of pacemaker capture threshold is important to ensure appropriate pacemaker function. During dual chamber pacing, it is sometimes difficult to identify evidence of atrial depolarization on surface electrocardiography (ECG), and this can interfere with the ability to ascertain atrial capture. We describe new methods for determining atrial capture threshold using a standard telemetered endocardial atrial electrogram (AEGM). For the first method, the atrial output is decremented until loss of atrial capture is demonstrated by the appearance of native P wave activity on the AEGM. The atrial capture threshold can then be accurately determined as the point at which a stepwise increase in atrial output results in extinction of the native P wave activity. The second method uses the direct visualization of the AEGM recorded between the ring electrode and pacemaker generator during unipolar (lead tip electrode) pacing. This requires the presence of a bipolar lead. Using this method of recording, it is possible to identify a signal after the atrial stimulus artifact during atrial capture, which disappears with loss of capture. This signal is consistent with a paced "evoked atrial potential" and allows verification of atrial capture. After validating the methods in two sets of test patients with clearly identifiable atrial depolarization on surface ECG, one method was successfully applied to a patient in whom atrial depolarization could not be reliably ascertained on surface ECG. These methods promise to be useful in selected patients in whom confirmation of atrial capture would otherwise be difficult.
Animals↗
Atrial automatic tachycardia-reversion pacemakers: their economic viability and impact on quality-of-life.
UNLABELLED: Refractory supraventricular tachyarrhythmias may be both difficult and costly to control medically and can interfere with the patient's lifestyle. Newer treatment modalities are available for their management, and these require comprehensive assessment. We therefore compared costs and selective indices of patient benefit in a group of 17 patients in whom an atrial antitachycardia (Intermedics Intertach 262-12) pacemaker was placed for refractory supraventricular tachyarrhythmias. Prior medical therapy was compared to subsequent automatic antitachycardia pacemaker treatment. The total medical costs (admissions, emergency room visits, office visits, and medication costs) and the number of hospitalizations and medications were compared prior to implantation (F/U 69.3 +/- 61 months) and after implantation (F/U 15.3 +/- 7.8 months). A detailed quality-of-life questionnaire was also obtained 36.6 +/- 11 months after implantation. RESULTS: There were significant per patient differences in total cost before and after implantation: monthly costs were $505 +/- $833 before pacemaker implantation and $105 +/- $117 monthly afterward (P less than 0.005). Pacemaker implantation hospitalization costs were $19,063 +/- $8,362. Monthly medication costs averaged $46 before versus $15 after implantation (P less than 0.01). The number of medication types also differed with an average 5.5 medication types per patient before versus 1.2 after implantation (P less than 0.001). There were 8.6 yearly hospital admissions in the whole group before implantation, versus 4.7 admissions in the group per year thereafter. Patients demonstrated significant improvement in 80% of the quality-of-life parameters studied. CONCLUSION: Adjunctive atrial automatic tachycardia-reversion pacemaker therapy may be cost-competitive over time when compared to medical therapy alone in patients with refractory supraventricular tachyarrhythmias and appears to improve overall quality-of-life.
Costs and Cost Analysis↗
Sensor-modulated dual chamber cardiac pacing: too much of a good thing too fast?
Explore the source record for details and available documents.
Atrial Fibrillation↗
Sustained effectiveness of an atrial antitachycardia pacemaker during follow-up.
Atrial antitachycardia pacemakers are indicated for medically refractory atrial tachyarrhythmias. To confirm long-term device effectiveness, we studied diagnostic data obtained in 17 patients with atrially-placed Intermedic "Intertach" pacemakers. The unit has programmable primary (P mod) and secondary (S mod) antitachycardia response protocols. Success of the P mod was defined as a P mod response first with no subsequent S mod response. Follow-up was for 595 days (+/- 302 days). The P mod was utilized first 88.2 +/- 102 times per patient interrogation with subsequent S mod use 21.1 +/- 53 times (P less than 0.0001). Results were also significant when P mod was compared to S mod in the first versus the last half of follow-up (both P less than 0.0001). These results suggest that the programmed P mod of the atrial "Intertach" tachycardia reversion pacemaker has sustained effectiveness in the treatment of medically refractory atrial tachyarrhythmias.
Atrial Flutter↗
The influence of endocardial electrode fixation status on acute and chronic atrial stimulation threshold and atrial endocardial electrogram amplitude.
UNLABELLED: The endocardial atrial electrogram or "P wave amplitude" (PWA) and pacemaker atrial stimulation thresholds are important parameters determining correct pacing system function. Pacemaker lead fixation mechanism and lead age may negatively influence these parameters. Therefore, we compared acute and chronic PWA and atrial stimulation thresholds in 33 patients with permanent transvenous atrial screw-in leads, follow-up 647 days +/- 297 days; and in 31 patients with nonscrew leads, follow-up 855 days +/- 512 days (P = ns). RESULTS: The PWA differed between the two lead types acutely (1.97 mV +/- 0.8 mV for screw-in versus 2.48 mV +/- 1.1 mV for nonscrew-in leads; P less than 0.05), but not chronically (2.21 mV +/- 0.8 mV vs 2.2 mV +/- 1.2 mV; P = ns). Acute and chronic atrial pacing thresholds did not differ between groups. We also analyzed an early interim PWA in a subgroup of patients (mean 31 days after implantation). The nonscrew fixation group interim PWA was 1.76 mV +/- 0.9 mV versus 2.7 mV +/- 1.2 mV at implant (P less than 0.001). The screw-in lead interim PWA was 2.04 mV +/- 0.9 mV versus 1.97 mV +/- 0.7 mV at implant (P = ns). CONCLUSIONS: (1) A significantly higher endocardial PWA occurs at the time of lead implantation in nonscrew versus screw-in lead groups, but the chronic PWA does not differ between the two groups. (2) A transient but marked early (mean approximately 31 days) attenuation of the PWA occurs only with nonscrew-in leads. (3) Atrial threshold stimulation energies do not differ between the two lead groups acutely or during follow-up.
Aged↗
Physical determinants of the endocardial P wave.
UNLABELLED: Reliable atrial sensing of intrinsic P wave activity is important to ensure optimal atrial or dual chamber pacemaker function. Various physical factors (e.g., posture, respiration, exercise) may influence P wave characteristics and impair adequate sensing. To investigate this phenomenon, we measured the average of three P wave amplitudes (PWA) and calculated slew rates from telemetered printouts acquired from Pacesetter pacemakers in 32 patients. These measurements were performed in various body positions, with upright exercise and in varying stages of respiration. RESULTS: the mean supine PWA increased on full inspiration (3.56 +/- 1.3 mV versus 3.25 +/- 1.2 mV during quiet respiration, P less than 0.001), and also increased significantly with full expiration. The mean PWA increased on assuming the erect position (3.25 +/- 1.2 mV increasing to 3.49 +/- 1.3 mV, P less than 0.001); in the upright position, the mean erect PWA during quiet respiration was not significantly influenced by the stage of respiration. The mean upright exercise PWA did not differ significantly from the preexercise erect PWA (3.50 +/- 1.2 with exercise, and 3.47 +/- 1.5 before exercise; P = NS). Calculated slew rates were not different lying versus standing. CONCLUSIONS: the mean supine PWA increases significantly at the extremes of respiration and on assuming the erect body position; upright exercise results in no appreciable change in the erect PWA. Atrial sensitivity adjustments based on standard supine testing should be adequate for all body positions.
Adolescent↗
Influence of cardiac pacing mode on the long-term development of atrial fibrillation.
Explore the source record for details and available documents.
Aged↗
Altered ventricular repolarization in central sympathetic dysfunction associated with spinal cord injury.
Complete injury to the cervical spinal cord results in total disruption of central sympathetic outflow. Although ventricular repolarization can be significantly influenced by disorders of autonomic function, the effects of cervical sympathectomy are unknown. Therefore, 40 subjects with complete chronic spinal cord injury were prospectively divided into 2 groups, half with total disruption of central sympathetic outflow (level of injury C5 to C8) known as the high level injury group, and half with nearly intact sympathetic innervation (T10 to L1) serving as controls. The completeness of autonomic dysfunction was verified by the cold pressor response. ST-segment analysis of the resting surface electrocardiogram revealed multilead ST elevation in the high level injury group, with maximum ST height significantly higher than the control group (131 +/- 21 [standard error] vs 47 +/- 8 microV; p = 0.0005). Unlike the control subjects, maximal arm ergometry exercise in the high level injury subjects failed to decrease ST-segment height (delta ST = -3 +/- 6 vs -43 +/- 14 microV in controls; p = 0.02). This difference persisted even after matching for exercise capacity. However, during exogenous stimulation with the sympathomimetic amine isoproterenol, ST-segment height in the high level injury group markedly decreased (mean delta ST = -84 +/- 26 vs -17 +/- 18 microV in controls; p = 0.04). Thus, central sympathetic dysfunction regularly results in multilead ST-segment elevation that decreases to or below isoelectric baseline during low dose isoproterenol infusion. Unlike normal subjects and individuals with normal variant ST-segment elevation, ST height is not altered by exercise. These findings document that ST-segment height in man is greatly influenced by central sympathetic nervous activity both at baseline and during physiologic and pharmacologic stress.
Autonomic Nervous System Diseases↗
Prevalence of catheter-induced valvular regurgitation as determined by Doppler echocardiography.
It has been suggested that cardiac catheters traversing competent heart valves may induce valvular regurgitation. To evaluate this possibility, continuous-wave and pulsed Doppler echocardiographic studies were performed immediately before, during and immediately after removal of various catheters in a total of 47 adult patients without clinical evidence of valvular regurgitation. With the tip of a 7Fr balloon flotation catheter positioned in the pulmonary artery, 9 of 36 patients (25%) had pulmonary regurgitation documented by continuous-wave Doppler. Evidence for regurgitation by pulsed Doppler examination was noted in 4 of these 9, with the regurgitant signal extending a mean of 1.8 cm into the right ventricular outflow tract. Similarly, a tricuspid regurgitant signal was present in 10 of 37 patients (27%) by continuous-wave Doppler and in 6 of these 10 by pulsed Doppler, with a mean regurgitant signal depth of 2.3 cm. Doppler examination also was performed in 7 patients (2 with aortic regurgitation) with a 7Fr pigtail catheter across the aortic valve, and in 4 patients (1 with tricuspid regurgitation) with a 6Fr bipolar pacing catheter across the tricuspid valve. Catheter removal resulted in no change in either the presence or absence of a regurgitant signal, or in the regurgitant signal depth in any of the patients studied. It is concluded that standard cardiac catheters neither induce Doppler-detected valvular regurgitation, nor do they affect the retrograde distance to which an existing regurgitant signal can be mapped.
Aortic Valve Insufficiency↗
Variation in P wave amplitude immediately after pacemaker implantation: possible mechanism and implications for early programming.
The P wave amplitude (PWA) plays an important role in determining atrial sensing capabilities. To assess early PWA change, we compared the unipolar PWA in 43 patients at the time of atrial lead placement, measured by a pacing systems analyzer, to the unipolar PWA recorded at the end of pacemaker surgery, from telemetered atrial endocardial electrograms. Individual PWA varied from a decrease of 5.2 mV to an increase of 2 mV (-63% to 267%). In 33 patients with active fixation leads, the implant PWA was 1.96 +/- 0.99 mV versus 2.4 +/- 1.4 mV after surgery. In 11 patients with passive fixation leads, the implant PWA was 2.8 +/- 1.9 mV versus 1.9 +/- 0.8 mV after surgery. The PWA change, measured as the difference between the postsurgical and implant PWA was 0.43 +/- 0.8 mV in active versus -0.86 +/- 1.6 mV in the passive fixation lead groups (P less than 0.05). Considerable change in individual P wave amplitude can therefore occur very early after pacemaker implantation. The direction differs significantly between active (predominantly positive) and passive fixation groups (predominantly negative). These data suggest that an adequate margin of safety is important when initially programming atrial sensitivity, particularly when using passive fixation leads.
Aged↗