Effect of controlled exercise training in coronary artery disease patients with and without left ventricular dysfunction assessed by cardiopulmonary indices

Cardiopulmonary indices were used to evaluate the effect of controlled exercise training prescribed on the basis of the heart rate at the ventilatory anaerobic threshold in coronary artery disease patients with and without impaired left ventricular function. Fifty-two patients aged 38-75 years were divided into four groups. The first three groups included patients with a left ventricular ejection fraction of > 45% at rest, as follows: group 1, 10 patients with single-vessel disease; group 2, 12 patients with two-vessel disease; group 3, 10 patients with three-vessel disease. Group 4 comprised 20 patients with left ventricular dysfunction (ejection fraction < 35%). The left ventricular ejection fraction was assessed by multigated acquisition radionuclear study. All patients underwent a cardiopulmonary exercise test before and after the program which lasted 6-9 months. The variables measured were oxygen consumption (VO2), CO2 output, minute ventilation, O2 pulse, and ventilatory anaerobic threshold. Significant improvements in maximal VO2, maximal O2 pulse, and ventilatory anaerobic threshold level were observed in groups 1, 2, and 4 (p < 0.1-0.0001), but not in group 3. These findings indicate that the overall cardiac function, as evaluated by cardiopulmonary indices, improves in patients with one- or two-vessel disease with good left ventricular function and in patients with impaired left ventricular function following an exercise training program. Severe coronary disease seems to limit improvement, even in the presence of a good left ventricular function. The results validate the heart rate at the ventilatory anaerobic threshold as the optimal training heart rate in coronary artery disease patients and the cardiopulmonary exercise test as a sensitive tool for evaluating exercise training results.

Analysis of high frequency QRS potential during exercise testing in patients with coronary artery disease and in healthy subjects

High resolution ECG waveforms from leads V3, V4, V5, and V6 were analyzed in two groups of male subjects before, during, and following treadmill exercise testing. Group A included 32 coronary artery disease (CAD) patients, with arteriographically proven > 75% obstruction of at least two main coronary arteries, and group B included 30 healthy subjects, without history or symptoms of CAD. Signal averaging and filtering techniques were used in order to enhance the signal-to-noise ratio of the recorded ECG. The averaged QRS waveforms were filtered between 150 and 250 Hz. QRS complexes of the four leads were combined to form a "precordial average complex" (PAC). The PAC signals were examined for each subject at different stages of the exercise test and two parameters were computed: the root mean square (RMS) voltage; and the peak amplitude. The values of RMS and peak amplitudes measured at each stage of the exercise test were normalized to the values at rest. Normalized RMS (NRMS) values at peak exercise, immediately after peak exercise, and during the recovery phase were found to be higher for the healthy subjects than for the CAD group (1.17 +/- 0.31 vs 0.94 +/- 0.26, P < 0.008 at peak exercise, 1.13 +/- 0.24 vs 0.84 +/- 0.19, P < 0.001 after peak exercise, 1.08 +/- 0.22 vs 0.94 +/- 0.17, P < 0.007 during recovery). Cut-off NRMS value of one had a sensitivity of 81.3% and a specificity of 70.0% in differentiating CAD patients from healthy subjects in the examined groups. Normalized peak amplitude (NAMP) values exhibited similar behavior, with higher values for the healthy subjects than for the CAD group (1.23 +/- 0.48 vs 0.94 +/- 0.36, P < 0.03 at peak exercise, 1.20 +/- 0.34 vs 0.83 +/- 0.28, P < 0.001 after peak exercise, 1.10 +/- 0.29 vs 0.94 +/- 0.23, P < 0.02 during recovery). Specificity of 73.3% and sensitivity of 71.8% were found using a postpeak NAMP cut-off value of 1. In conclusion, the present study shows that using high frequency ECG may contribute to identifying patients with CAD. Further studies in larger groups of patients are required to better define the true predictive value of the method described for the diagnosis of CAD.

Relationship between ventilatory threshold and onset of ischaemia in ECG during stress testing

The study was carried out to determine the relationship between ventilatory threshold and the onset of ischaemia, as shown on the ECG (horizontal and/or descending ST depression of 0.05 mV, on average). Twenty-seven male patients (aged 58 +/- 7 years) with angiographically documented coronary artery disease (CAD) were assessed by cardiopulmonary exercise testing without medication. Oxygen uptake (VO2), heart rate (HR), rate-pressure-product (RPP) and blood lactate were measured and/or calculated every 30 s during exercise. In addition, 10 patients, comparable with the above group, were examined to find out the acute effects of isosorbide dinitrate (ISDN) at ventilatory threshold in relation to ischaemic threshold. The first cardiopulmonary exercise test was carried out without medication, the second 1 h later with 5 mg ISDN, taken sublingually 30 min before the test.

RESULTS

(means, SD): (1) The mean ventilatory threshold preceded the ischaemic threshold in relation to exercise capacity (48 +/- 14 vs 55 +/- 20 watts; P < 0.05), VO2.kg-1 (10.0 +/- 2.2 vs 12.0 +/- 2.9 ml.kg-1.min; P < 0.05), HR (93 +/- 15 vs 100 +/- 16.min-1; P < 0.01), RPP (15095 +/- 4424 vs 17166 +/- 5245; P < 0.01) and blood lactate (1.28 +/- 0.53 vs 1.44 +/- 0.60 mmol.l-1; P < 0.05). (2) This relationship was observed more often in the subgroup of patients with angina during cardiopulmonary exercise testing or with myocardial infarction or with three-vessel disease than in patients without angina or infarction or with one- and two-vessel disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Importance of reciprocal ST segment depression in leads V5 and V6 as an indicator of disease of the left anterior descending coronary artery in acute inferior wall myocardial infarction

The purpose of this study was to determine the coronary angiographic correlations (specifically disease of the left anterior descending coronary artery) of reciprocal ST segment depression appearing during inferior acute myocardial infarction. Forty six patients (41 men and five women; mean age 56 years) were allocated into two groups based on the extent of precordial ST segment depression: widespread (V1-V6) ST depression v localised (V1-V4) ST depression. Patients with no reciprocal ST depression or patients with ST depression in V1-V4 but with ST elevation in V5 and V6 (inferolateral acute myocardial infarction) were excluded. All patients were catheterised during hospital admission for infarction. Twenty four of the 28 patients with ST depression in V1-V6 had significant lesions in the left anterior descending coronary artery whereas 16 of the 18 patients with ST depression in V1-V4 had insignificant or no lesions in the left anterior descending artery. The sensitivity, specificity, and positive and negative predictive values of widespread ST depression in predicting disease in the left anterior descending coronary artery were 92%, 80%, and 86% and 89% respectively. In patients with inferior acute myocardial infarction and precordial ST depression, the extent of ST depression is of clinical significance. Widespread (V1-V6) ST depression suggests disease of the left anterior descending coronary artery, whereas localised ST depression (V1-V4) indicates its absence.

Natural course of electrocardiographic components and stages in the first twelve hours of acute myocardial infarction

Time course evolution of R, Q, T and ST components of the electrocardiogram during the first 12 hours of an acute myocardial infarction was studied. A comparison between anterior-extensive and anteroseptal wall infarctions (anterior group), and inferior-extensive and inferior wall infarction (inferior group) showed appearance of significant Q waves within two hours in both groups. R wave loss was nearly a mirror image of Q wave development in both groups. T waves became negative and ST more isoelectric earlier in the inferior than in the anterior group. When combined variations of the four electrocardiographic components were analyzed, four stages of acute infarction were delineated. Stage I--tall R, no Q, ST elevation and positive T; Stage II--significant Q wave appearance; Stage III--negativity of T waves; and Stage IV--ST isoelectric. The inferior group reached stages III-IV within 12 hours; the anterior group remained mostly in stage II. An early appearance of Q waves correlated well with rapid progression to stages III-IV within 12 hours in both infarction groups.

Beta-endorphins in acute myocardial infarction

The endogenous peptide B-endorphin (B-EP) is closely connected with different aspects of homeostasis, behavior, and in particular with the perception of pain. The purpose of this study was to investigate the correlation between: the level of plasma B-EP and the intensity of pain in acute myocardial infarction (AMI); and the B-EP and specific enzymes for AMI serum glutamic oxolo-acetic transferase, lactate dehydrogenase, and creatine phosphokinase and some stress hormones (cortisol, growth hormone). Twenty-six patients hospitalized in the CCU for acute MI were studied during the first 72 hours from the onset of symptoms. Seven normal subjects served as controls. Blood was taken for hormone and B-EP evaluation before treating the patients by opiates. Plasma B-EP levels were determined using the protocol of the Immunonuclear Corporation (Stillwater, MN). Statistical analysis of the results showed: Nonsignificant differences between B-EP levels of all MI patients and control group. Unaltered B-EP levels in patients with acute MI suffering from moderate pain. Significant differences in drop of B-EP in the group with most severe pain (p less than 0.025). A tendency toward decreased B-EP in patients suffering from more prolonged pain (greater than 6 hours). Significant negative correlation was shown between B-EP and chest pain intensity (0-4 graduation) (r = 0.8, p less than 0.01); lactate dehydrogenase (r = 0.7, p less than 0.01); serum glutamic oxolo-acetic transferase (r = 0.6, p less than 0.01); creatine phosphokinase (r = 0.6, p less than 0.05; plasma cortisol level (r = 0.5, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Alternating Wenckebach periods in acute inferior myocardial infarction: clinical, electrocardiographic, and therapeutic characterization

We report on twelve patients with alternating Wenckebach periods (AWP) occurring during an acute inferior myocardial infarction (AIMI). There were nine males and three females, with a mean age of 61 years (range, 43 to 75). AWP appeared during the first 48 hours of the AIMI in 10 patients and on the fourth day of hospitalization in two patients. AWP occurred spontaneously in nine patients and following the administration of atropine in the remaining three patients. Mean systolic blood pressure significantly decreased during AWP as compared to the period preceding or following the bradyarrhythmia (93 +/- 42 mmHg vs 123 +/- 37 mmHg, p less than 0.02). Killip functional class was significantly higher during AWP as compared to the period preceding or following the bradyarrhythmia (2.1 +/- 1.2 vs 1.5 +/- 0.8, p less than 0.02). Pacemaker therapy was initiated prophylactically in two patients, because of syncope in six, because of hemodynamic deterioration in two, and for syncope and hemodynamic deterioration in two. Three patients died in cardiogenic shock despite pacemaker therapy. No evidence of right ventricular infarction was seen in the patients. Atropine administration during AWP significantly increased the sinus rate and significantly decreased the ventricular rates and the systolic blood pressure. In addition, three patients developed long bouts of paroxysmal AV block. Isoproterenol administration improved AV conduction in one patient, caused no change in two patients and induced non-sustained ventricular tachycardia in three patients. In conclusion, AWP occurring during AIMI is a symptomatic bradyarrhythmia associated with hemodynamic deterioration.(ABSTRACT TRUNCATED AT 250 WORDS)

Carotid sinus syndrome: an overlooked cause of syncope

Carotid sinus syncope was diagnosed during a 2-year period in 21 men and 5 women, aged 51 to 80 years, who had experienced 1 to 30 syncopal episodes during periods of time which varied from 1 day to 6 years. In 19 of these patients there was evidence of organic heart disease. Carotid sinus hypersensitivity of the cardioinhibitory type was present in 14 patients, the vasodepressor type in 1 patient, and a mixed type in 7 patients. In four patients with the cardioinhibitory response, the possibility of the vasodepressor response was not excluded. A pacemaker was placed in 17 patients, deferred in 4 patients and refused by 5 patients. Follow-up of patients with pacemakers over 9.5 +/- 7.0 (SD) months revealed recurrence of symptoms in two patients due to a previously unrecognized vasodepressor response. Follow-up of the patients without pacemakers was brief (4.6 +/- 3.7 months), and they remained asymptomatic, except for one patient with recurring vertigo.

Left and right ventricular function in inferior acute myocardial infarction and significance of advanced atrioventricular block

Of 139 consecutive patients with a first inferior acute myocardial infarction, 26 (19%) had advanced atrioventricular (AV) block and 113 (81%) did not. All were evaluated by 2-dimensional echocardiography (2-D echo) and radionuclide angiography. Patients with advanced AV block had lower radionuclide left ventricular (LV) ejection fraction (51 +/- 10 vs 58 +/- 11%, p less than 0.01), higher LV wall motion score on 2-D echo (5.6 +/- 2.6 vs 3.1 +/- 2.7, p less than 0.001), lower radionuclide right ventricular (RV) ejection fraction (32 +/- 15 vs 39 +/- 16%, p less than 0.001) and higher RV wall motion score on 2-D echo (3.4 +/- 1.7 vs 1.5 +/- 2, p less than 0.002) than did patients without AV block. The incidence rate of RV dysfunction was higher in patients with advanced AV block (78 vs 40%, p less than 0.02), and the mortality rate was also higher (although not significantly) in patients with advanced AV block (15 vs 6%). In conclusion, patients with inferior acute myocardial infarction and advanced AV block have larger infarct sizes (as seen on radionuclide angiography and 2-D echo) and lower RV and LV function than patients without AV block. This finding may explain the higher mortality rate observed in this group.