Ventricular arrhythmias induced by dynamic and static exercise in relation to coronary artery bypass grafting.

The effect of coronary artery bypass grafting (CABG) on exercise-induced ventricular arrhythmias was examined in 53 patients. A bicycle exercise test and an isometric handgrip exercise test were performed before and 3 months after CABG. Exercise-induced ventricular arrhythmias were detected preoperatively in 14 patients (26%), in 13 during the bicycle test and in 11 during the handgrip test, and in 18 patients (34%) after CABG. Thus, CABG had no significant effect on the occurrence of exercise-induced ventricular arrhythmias. Nine patients had new exercise-induced ventricular arrhythmias after CABG, 8 of whom had evidence of previous myocardial infarction, whereas only 8 of the 35 patients (23%) without postoperative ventricular arrhythmias had had a previous infarction. The rate of graft patency or improvement in exercise tolerance in patients with new postoperative arrhythmias did not differ from that in patients who did not have exercise-induced arrhythmias after CABG. The results confirm that CABG has no influence on the occurrence of ventricular arrhythmias induced by physical exercise. Patients with a previous myocardial infarction appear to be prone to new ventricular arrhythmias despite successful revascularization.

Detection of coronary artery disease by thallium imaging using a combined intravenous dipyridamole and isometric handgrip test in patients with aortic valve stenosis.

Detection of coronary artery disease (CAD) in patients with aortic valve stenosis (AS) is clinically difficult. Thallium-201 images were generated in 27 patients with AS during combined intravenous dipyridamole and handgrip test, which induces a marked acute increase in coronary blood flow. Isolated AS was noted in 21 patients and combined AS and aortic regurgitation in 6. Thirteen patients had more than 50% diameter stenosis in 1 or more coronary arteries on angiography. Eleven of them had reversible perfusion defects on post-stress thallium scans (sensitivity 85%). Two patients had thallium defects without angiographic evidence of significant CAD (specificity 86%). In the other 12 patients with normal coronary angiographic findings, the thallium scans were normal. Two patients had dizziness and hypotension after dipyridamole infusion, which disappeared during the handgrip test; 2 others had chest pain during handgrip. One of them was treated with aminophylline and the other with aminophylline and nitroglycerin. No other adverse effects were reported by the patients and no major complications occurred during stress testing. Thus, thallium imaging during combined intravenous dipyridamole and handgrip test appears to be a promising noninvasive method of revealing CAD in patients with AS.

Effect of coronary artery bypass grafting on left ventricular response to isometric exercise.

The left ventricular (LV) response to isometric exercise was evaluated in 20 patients who performed handgrip exercise tests before and 3 months after coronary artery bypass grafting. Preoperative LV ejection fraction (EF) decreased during the handgrip test from 0.57 +/- 0.08 to 0.49 +/- 0.09 (p less than 0.001); the ratio between the LV peak systolic pressure (PSP) and end-systolic volume index (ESVI) did not change. In 12 patients with patent grafts, the LVEF after operation did not change (0.54 +/- 0.06 at rest and 0.56 +/- 0.06 during handgrip exercise) and PSP/ESVI ratio increased from 4.5 +/- 1.5 to 5.6 +/- 2.1 mm Hg/ml X m-2 (p less than 0.001) during exercise. In 8 patients with occluded grafts, the LVEF after operation decreased from 0.56 +/- 0.10 to 0.48 +/- 0.06 (p less than 0.02), whereas PSP/ESVI did not change during handgrip exercise. Thus, the LV response to isometric handgrip exercise appears to improve after coronary artery bypass grafting in patients with patent grafts, but not in patients with 1 or more occluded grafts.

Comparison of dipyridamole-handgrip test and bicycle exercise test for thallium tomographic imaging.

Seventy-three patients with angina pectoris and 20 with atypical chest pain, who underwent coronary angiography, were examined by single-photon emission computed thallium tomography (TI-SPECT) using a combined dipyridamole-handgrip stress test. Perfusion defects were detected in 78 of 81 patients with angiographically significant coronary artery disease (CAD) (sensitivity 96%). In 9 of 12 patients without CAD, the thallium images were normal (specificity 75%). Thirty-five patients with CAD were reexamined by TI-SPECT using a dynamic bicycle exercise stress test. The sensitivity of the dipyridamole-handgrip test did not differ from the bicycle exercise test in diagnosing the CAD (97% vs 94%). Multiple thallium defects were seen in 19 of 22 (86%) patients with multivessel CAD by the dipyridamole-handgrip test but only in 14 of 22 (64%) by the bicycle exercise test. Noncardiac side-effects occurred in 17 of 93 (18%) patients after dipyridamole infusion. Cardiac symptoms were less common during the dipyridamole-handgrip test than during the bicycle exercise (15% vs 76%, p less than 0.01). These data suggest that the dipyridamole-handgrip test is a useful alternative stress method for thallium perfusion imaging, particularly in detecting multivessel CAD.

Pharmacokinetics of digoxin in patients with acute myocardial infarction.

The effects of acute myocardial infarction on the pharmacokinetics of digoxin were studied. Digoxin, 0.75 mg, was given orally to 12 patients with left-sided cardiac failure due to acute myocardial infarction and to 9 healthy control subjects. Serum concentration of digoxin in the first 4 hours and the area under the serum concentration-time curve in the first 12 hours after administration of the drug were lower in patients with infarction than in control subjects (P less than 0.01). The 24 hour area under the concentration curve, the amount excreted in urine and the renal clearance did not differ between the groups. The 24 hour area under the concentration curve correlated with the predigoxin pulmonary capillary wedge pressure and with heart rate (P less than 0.01). The decrease of renal clearance of digoxin was related to the serum activity of MB isoenzyme of creatine kinase (P less than 0.001). Morphine reduced and delayed the peak serum concentrations of digoxin (P less than 0.001). Thus, the absorption of oral digoxin was slower and the peak concentrations remained lower in patients with acute myocardial infarction than in healthy control subjects. However, the total amount of digoxin absorbed was unchanged.

Prevalence and prognostic significance of exercise-induced ventricular arrhythmias after coronary artery bypass grafting.

Exercise-induced ventricular arrhythmias occur often after coronary artery bypass grafting (CABG), but their prognostic significance is unknown. Two hundred patients examined by exercise electrocardiography and cardiac catheterization (including left ventriculography, bypass graft and native coronary artery angiography) before and 3 months after CABG were prospectively followed up. Exercise-induced ventricular arrhythmias occurred more often after (49 of 200 patients, 24.5%) than before (32 of 200 patients, 16.0%) CABG (p less than 0.05). There were no differences between the patients with and without ventricular arrhythmias in the prevalence of graft patency (79 vs 80%) or the postoperative ejection fraction (57 +/- 9 vs 57 +/- 12%). Ten cardiac deaths occurred during the mean follow-up time of 61 +/- 19 months, 8 of which were witnessed sudden cardiac deaths. All cardiac deaths occurred in patients who did not have exercise-induced ventricular arrhythmias after CABG. The postoperative ejection fraction was lower in the cardiac death patients (42 +/- 16%) than in the survivors (58 +/- 10%) (p less than 0.01). No other clinical or angiographic variable predicted the occurrence of cardiac death. Thus, the prevalence of exercise-induced ventricular arrhythmias increases after CABG, but the occurrence of ventricular arrhythmias does not indicate an increased risk of cardiac death.

Prevalence and prognostic significance of complex ventricular arrhythmias after coronary arterial bypass graft surgery.

To assess the prevalence and long-term prognostic significance of complex ventricular arrhythmias after coronary arterial bypass graft surgery, 126 patients were studied by 24-hour ambulatory electrocardiographic recordings and cardiac catheterizations (including left ventricular, coronary arterial and bypass graft angiograms) before and 3 months after surgery, and then prospectively followed-up for a mean of 50 months. Complex ventricular arrhythmias (ventricular premature complexes greater than 30/hour, multiform and/or repetitive complexes) occurred more commonly after than before surgery (in 49/126 vs. 30/126 patients, P less than 0.05). In 18 patients (14%) who had significant worsening of ventricular arrhythmias, the ejection fraction decreased significantly (from 56 +/- 13% to 50 +/- 15%, P less than 0.05) after operation. During the period of follow-up, there were 4 witnessed sudden cardiac deaths. Complex ventricular arrhythmias tended to be more prevalent in patients who died suddenly (in 100%) compared to survivors (in 37%), but their presence did not predict the subsequent sudden death when ejection fraction was included in the stepwise regression model. None of the patients with an ejection fraction over 40% suffered sudden death despite the prevalence of complex arrhythmias in 32% of these patients. Thus, complex ventricular arrhythmias tend to occur more frequently after than before bypass surgery and their occurrence appears to be related to impairment of left ventricular function. Patients with well preserved ventricular function are at low risk of dying suddenly despite presence of complex ventricular arrhythmias after surgery.

Asymptomatic coronary artery disease in diabetes: relation to common risk factors, lipoproteins, apoproteins and apo E polymorphism.

The risk factors for asymptomatic coronary artery disease (CAD) were examined in 138 diabetic patients. Following non-invasive screening examinations (exercise electrocardiography, dynamic thallium scintigraphy, 24-h electrocardiographic recording), CAD was confirmed angiographically in 21 symptom-free diabetic subjects with an ischaemic finding in at least one of the non-invasive tests. The prevalence of asymptomatic CAD in this cohort of diabetic patients was 21/132 (16%), which may be an underestimation because 6 patients refused angiography. Risk factors (age, diabetes, smoking, hypertension, serum lipoproteins, apoproteins and apo E phenotypes) were analysed according to the presence or absence of CAD. Multivariate logistic stepwise analysis did not show any definite changes of serum lipids, lipoproteins and apoproteins in type 1 (n = 72) and type 2 (n = 66) diabetic patients with or without asymptomatic CAD. The only factors associated with asymptomatic CAD were the duration of diabetes (P < 0.005) and the age of the patient (P < 0.05). These results suggest that in diabetic patients the major risk factor for premature coronary atherosclerosis is diabetes itself. Assessment of other risk factors does not seem to define any subgroup with asymptomatic CAD.

The relationship of ventricular arrhythmias to the angiographically and scintigraphically estimated extent of ventricular damage late after myocardial infarction.

In order to study the quantitative relationship of ventricular arrhythmias to myocardial damage and ischemia, 61 patients with a previous myocardial infarction (at least 6 months previously) were studied by 24-hour ambulatory ECG monitoring, cardiac catheterization, and thallium-201 scintigraphy. Thirty-five patients (57%) had no ectopic beats or only infrequent, unifocal ones and 26 patients (43%) had complex ventricular arrhythmias. Left ventricular function was lower in the latter (p less than 0.05), but the number of diseased vessels did not differ in the two groups. The reduction of thallium activity in the infarct area was more marked in patients with complex arrhythmias (p less than 0.001). Multiple thallium defects were not more common in arrhythmia patients, however. These data support the view that complex ventricular arrhythmias are more closely related to the severity of ventricular damage than the presence of myocardial ischemia remote to the area of previous infarction.

Dynamic and static exercise haemodynamics after acute myocardial infarction.

The cardiovascular responses to dynamic and static exercises were studied in 20 patients by exercise tests performed at 3 weeks and 12 weeks after acute myocardial infarction. The left ventricular size and volume output were determined by radiocardiography. The mean cardiac output during dynamic exercise at the second study was 24% (p less than 0.05) higher than at the first study, mainly because the peak heart rate was 19% (p less than 0.05) higher. The left ventricular end-diastolic volume or its response to ergometric exercise did not change during the 3-month follow-up and the ejection fraction and stroke volume showed minor changes only. During static exercise a 3% better increase in cardiac output was seen from 3 to 12 weeks, without any improvement in ejection fraction. At the 12-week study the changes in cardiac performance during ergometric exercise were not related to the site of infarction or drug therapy. During static exercise slight improvement of cardiac output, stroke volume and ejection fraction responses were seen in the course of time, but only in the patients with inferior infarction and in those not receiving digoxin and/or diuretics. The mean cardiac output during dynamic exercise improved by one-quarter, mainly due to a higher peak heart rate, in the course of the 3-month follow-up after myocardial infarction. Otherwise, haemodynamic variables during dynamic or static exercises within 3 months showed insignificant sequential changes only.

Theophylline and salbutamol in combination in patients with obstructive pulmonary disease and concurrent heart disease: effect on cardiac arrhythmias.

We compared the frequency and severity of cardiac arrhythmias during combined oral theophylline and inhaled salbutamol vs. salbutamol therapy alone in 18 patients with moderate to severe chronic obstructive pulmonary disease who had concurrent cardiac disease. Seventeen patients showed at least one supraventricular premature complex (SVPC) on the 24-h ECG recording when receiving salbutamol alone: eight patients had isolated SVPCs, less than 10/h; five patients had greater than or equal to 10 SVPCs/h; eight patients showed runs of supraventricular tachycardia or paroxysmal atrial fibrillation. Seventeen patients also had at least one ventricular premature complex: seven patients had less than 10 isolated PVCs/h, five patients greater than or equal to 10 PVCs/h; eight patients had paired or multifocal PVCs and one patient a run of ventricular tachycardia. The addition of oral theophylline at an average dose of 600 mg in the evening (blood concentrations showed a mean maximum of 13.4 +/- 4.0 (SD) and minimum of 5.5 +/- 2.9 mg/l) had no influence on the frequency or severity of either ventricular or supraventricular arrhythmias. Thus, cardiac arrhythmias are very common in patients with chronic obstructive pulmonary disease and concomitant heart disease, but oral theophylline added to a regimen of salbutamol does not seem to affect the occurrence or severity of arrhythmias.

Cardiovascular responses to static and dynamic effort three weeks after myocardial infarction.

Left ventricular responses to dynamic and static exercises were compared in 20 patients three weeks after myocardial infarction. Radiocardiography was used to determine the ventricular volumes at rest and during hand grip and bicycle exercise tests. The dynamic exercise increased cardiac output (p less than 0.001), and the end-diastolic volume of the left ventricle increased (p less than 0.005) from the resting value while the ejection fraction decreased (p less than 0.005). Static hand grip exertion did not increase cardiac output or the end-diastolic volume. Decrease of the stroke volume and the ejection fraction (p less than 0.001 both) again reflected pump dysfunction during the afterload stress. Our data revealed that patients with recent myocardial infarction had a range of ventricular responses to dynamic exercise. Poor response in the ejection fraction was noted in anterior infarction and in those patients using digoxin and/or diuretics after infarction. During static exercise, on the other hand, impairment of cardiac performance was constant, irrespective of the site of infarction. Reduction of the ejection fraction was greater during static exercise in the patients receiving digoxin and/or diuretics than in those not taking these drugs.

Left ventricular function after dynamic and static exercise in ischaemic heart disease.

The effects of dynamic and static exercise on left ventricular function in ischaemic heart disease were studied in 20 patients with angiographically documented coronary artery disease. Radiocardiography was used to determine left ventricular volumes at rest and during exercise tests. Dynamic exercise increased cardiac output significantly (p less than 0.001) in the 10 patients with one-vessel coronary artery disease, whereas end-diastolic and end-systolic volume and ejection fraction did not change from the resting values. In contrast, in the 10 patients with multiple coronary vessel disease significant increases in end-diastolic (p less than 0.05) and end-systolic volumes (p less than 0.001) were observed during dynamic exercise. Cardiac output increased by only 21% (p less than 0.05) while a decrease in ejection fraction (p less than 0.005) reflected pump dysfunction in these patients. Static exercise did not change cardiac output or end-diastolic volume significantly. The end-systolic volumes increased in both patient groups, more so in the patients with multi-vessel coronary involvement (p less than 0.005 and p less than 0.01, respectively). These data revealed a different left ventricular volume response to dynamic exercise in the patients with one-vessel coronary artery disease compared with those with multi-coronary involvement. The afterload stress taking place during the static exercise, on the other hand, evoked left ventricular dysfunction very sensitively and similarly, irrespective of the extent of coronary artery stenoses.

Left ventricular response to dynamic and static exercise: evaluation by radiocardiography in healthy men.

The effects of dynamic and static exercise on left ventricular haemodynamics were compared in 13 healthy male volunteers using single detector radiocardiography. Static hand grip effort was performed for four minutes at 30% of the maximum contraction. During dynamic exercise the subjects bicycled on an ergometer to 85% of the predicted heart rate for their age. Static exercise increased the heart rate, systolic and diastolic blood pressure and cardiac output (p less than 0.001 for all), but there were no significant changes in the stroke volume, left ventricular end-diastolic volume or ejection fraction from the resting values. Dynamic exercise in a supine position clearly increased the heart rate, systolic blood pressure and cardiac output (p less than 0.001 for all) to a greater extent than the hand grip, together with a significant augmentation of the stroke volume (p less than 0.001) and the ejection fraction (p less than 0.01). The dynamic exercise produced only an insignificant increase in left ventricular end-diastolic volume. Thus, the normal left ventricular volume response to the increase in preload during dynamic exercise was a significant augmentation of stroke volume and ejection fraction. On the other hand, the static exercise in the same subjects mainly increased the left ventricular afterload while the left ventricular volume changes remained minimal.

Thallium scintigraphy in prediction of occlusion of bypass grafts in asymptomatic and symptomatic patients.

To evaluate thallium scintigraphy in predicting coronary artery bypass graft patency, exercise thallium scintigraphy and selective graft and native vessel angiograms were performed in 22 asymptomatic and 29 symptomatic consecutive patients three months after coronary artery bypass grafting (CABG). Twelve out of 22 asymptomatic patients (55%) had reversible thallium defects on postoperative images; in 10 patients the postoperative scans were normal. The graft patency was significantly lower in asymptomatic patients with abnormal thallium perfusion compared to those with normal perfusion after CABG (68% vs. 91%, p less than 0.05). The rate of graft patency in symptomatic patients was 66/87 (76%). Thallium scintigraphy was 77% sensitive and 78% specific in detecting one or more stenosed or occluded bypass grafts in patients without angina (accuracy 77%). When data from exercise electrocardiography were combined with scintigraphy, all but one patient with incomplete revascularization could be detected (positive predictive accuracy 92%). In symptomatic patients, thallium scintigraphy accurately predicted the presence or absence of graft occlusion in 24/29 (83%) cases. Thus, abnormal myocardial perfusion due to stenosis or occlusion of bypass grafts is common in both asymptomatic and symptomatic patients after CABG. Thallium scintigraphy together with exercise electrocardiography appear to be useful non-invasive methods in detecting painless myocardial ischemia and in predicting bypass graft occlusion after CABG.

Detection of coronary artery disease by thallium scintigraphy in patients with valvar heart disease.

In patients with valvar heart disease detection of coronary artery disease by conventional non-invasive methods may be difficult. The usefulness of thallium-201 exercise scintigraphy for detecting coronary artery disease was evaluated in 16 patients with aortic stenosis, 17 with aortic regurgitation, nine with mitral stenosis, and six with mitral regurgitation who were investigated by coronary angiography. Only two of 21 patients with greater than or equal to 50% coronary artery obstruction had normal thallium images. Three patients without angiographic evidence of coronary artery stenoses had perfusion defects demonstrated by thallium scintigraphy. Only one patient with greater than or equal to 75% coronary stenosis had a normal thallium scan. Angina pectoris or ST segment depression evoked by exercise test were not useful in distinguishing patients with coronary artery disease from those with normal coronary vessels. These data suggest that thallium exercise scintigraphy may be a useful non-invasive test for detecting coronary artery disease in patients with valvar heart disease.

Efficacy and safety of anticoagulant therapy started pre-operatively in preventing coronary vein graft occlusion.

Oral anticoagulant therapy with warfarin commenced pre-operatively (n = 102) to prevent coronary artery vein graft occlusions was compared in terms of efficacy and safety with dipyridamole and aspirin (n = 130) in a randomized consecutive series of patients. Anticoagulant therapy was started at least 2 weeks before coronary artery bypass surgery (CABG) and antiplatelet therapy was started at least 3 days before CABG with dipyridamole followed by a combination of 250 mg aspirin once a day via a nasogastric tube 6 h after CABG. Overall, vein graft patency at 3 months after surgery did not differ significantly between the anticoagulant group (203/275, 74%) and dipyridamole-aspirin group (238/311, 77%), but the occlusion rate for grafts with endarterectomy was higher in the anticoagulant (46%) than in the dipyridamole and aspirin group (16%), (P less than 0.05). The rate of peri-operative complications including deaths, re-operation and myocardial infarction was higher in the anticoagulant than antiplatelet group (26.5% vs 13.8%, P less than 0.05). The occurrence of postoperative bleeding complications did not differ significantly between the groups. Thus, oral anticoagulant therapy commenced pre-operatively has no advantages over conventional antiplatelet therapy in patients who undergo CABG. Neither antithrombotic regimens proved to be satisfactory for preventing acute bypass vein graft occlusions in this patient population with advanced coronary artery disease.

Pericardial effusion after cardiac surgery: incidence, relation to the type of surgery, antithrombotic therapy, and early coronary bypass graft patency.

To investigate the incidence and clinical significance of postoperative pericardial effusion (PE), the presence of PE was evaluated by echocardiography, 1 and 2 weeks postoperatively, in 50 patients after insertion of a valve prosthesis and in 100 patients after coronary bypass surgery (50 patients receiving a combination of aspirin and dipyridamole and 50 receiving warfarin). PE was found during either procedure in 77% of patients and was marked in 29%. Symptoms of postpericardiotomy syndrome (p less than 0.05), pericardial friction rub (p less than 0.01), atrial arrhythmias (p less than 0.05), cardiac enlargement (p less than 0.01), and pleural effusion (p less than 0.05) were detected more frequently in patients with PE than in those without PE. PE was not related to the type of antithrombotic therapy, the rate of coronary bypass graft occlusion, or the type of cardiac surgery. However, the use of the left internal mammary artery as a coronary bypass graft was associated with a slightly higher incidence of PE (p less than 0.05). One patient (0.7%) required surgical drainage of PE. It was concluded that PE is a common and benign finding after cardiac surgery and usually disappears without specific therapy.