Improved cardiac function and quality of life following upgrade to dual chamber pacing after long-term ventricular stimulation.

AIMS: Many patients with sinus node disease or atrioventricular block have previously received pacemakers with only ventricular stimulation (VVI or VVIR). This study aimed to investigate whether quality of life and cardiac function were affected by an upgrade to dual chamber pacing (DDDR or DDIR) following long-term ventricular stimulation. METHODS: After implantation of an atrial lead and a DDDR pulse generator, a randomized, double-blind crossover study was performed in 19 patients, previously treated with ventricular pacing for a median time of 6 X 8 years. Patients were randomized to 8 weeks with either VVIR or DDDR/DDIR pacing; after this time, the other mode was programmed for 8 weeks. At the end of each period, the patients' quality of life was evaluated and echocardiography was performed together with Holter monitoring and blood samples for brain natriuretic peptide. RESULTS: Sixteen of the patients preferred DDDR and two VVIR pacing (P=0 X 001); one was undecided. Seven patients demanded an early crossover while paced in the VVIR mode, vs none in the DDDR mode (P=0 X 008). Quality of life was higher in the DDDR mode in 11 of 17 modalities, reaching statistical significance for dyspnoea (P<0 X 05) and general activity (P<0 X 05). Echocardiography showed significantly larger left ventricular end-diastolic dimensions in the DDDR mode (P=0 X 01), whereas end-systolic dimensions did not differ. Left ventricular systolic function was significantly superior in the DDDR mode (mean aortic velocity-time integral: P<0 X 001) and left atrial diameter was significantly smaller in the DDDR mode (P=0 X 01). The plasma level of brain natriuretic peptide was significantly lower in DDDR mode (P=0 X 002). CONCLUSION: An upgrade to dual chamber rate adaptive pacing results in significantly improved quality of life and cardiac function as compared to continued VVIR stimulation and should thus be considered in patients with ventricular pacemakers who have not developed permanent atrial fibrillation or flutter.

Streptokinase antibodies inhibit reperfusion during thrombolytic therapy with streptokinase in acute myocardial infarction.

OBJECTIVES: To evaluate the influence of pretreatment IgG against streptokinase on the outcome of streptokinase treatment in acute myocardial infarction. SETTING: Coronary care unit. DESIGN: From 88 patients admitted to the coronary care unit due to chest pain, blood samples were taken for determination of the pre-existing titre of antibodies against streptokinase. The patients were treated and monitored according to standard protocols. Fifty of the patients received thrombolytic therapy with streptokinase due to acute myocardial infarction and were monitored with continuous dynamic vectorcardiography, making possible the continuous analysis of ST- and QRS-vector changes and determination of the event of reperfusion. None of these 50 patients had been given streptokinase therapy previously. RESULTS: According to the vectorcardiographic criteria 21(42%) patients had signs of early (within 2 h) reperfusion after streptokinase therapy. These patients had lower pre-existing antibody titres than patients without signs of reperfusion (mean values 0.20 and 0.45 arbitrary units, P = 0.01). None of the patients with a titre higher than 0.50 arbitrary units (nine patients) had signs of early reperfusion. Of the 41 patients with a titre lower than 0.50 arbitrary units 52.5% had signs of early reperfusion. CONCLUSION: The present investigation indicates that pre-existing streptokinase antibodies play an important role in reperfusion failure during thrombolytic therapy with streptokinase in acute myocardial infarction. Therefore, the determination of streptokinase antibodies may differentiate between those patients who may benefit from streptokinase treatment and those who should be treated with some other regime.

Upgrade to dual chamber pacing after long-term ventricular stimulation: feasibility and intermediate term follow-up.

AIMS: To evaluate the feasibility and follow-up results of atrial lead implantation and a change to dual chamber pacing following long-term treatment with single chamber ventricular stimulation. METHODS AND RESULTS: During a 30-month period, 70 consecutive patients with ventricular pacemakers were referred for pulse generator exchange or lead reoperation. Using defined criteria, an upgrade procedure was considered indicated in 34 of the cases (49%); these patients had a mean age of 74.8+/-8.8 years, and had been treated with VVI or VVIR pacing for a mean time of 7.8+/-3.8 years (range 1.8-17). An atrial lead was successfully implanted via ipsilateral subclavian venipuncture through the existing pectoral pacemaker pocket in 33 of the 34 cases (97% of the attempts). Postoperatively, one atrial lead dislodgement was seen, and another patient required atrial lead adjustment due to P wave undersensing. The mean follow-up period was 14+/-10 months. During this time, four patients developed permanent atrial fibrillation (annual incidence 11%. In 82% of the patients in whom an upgrade procedure was attempted, dual chamber pacing was maintained at the end of follow-up. CONCLUSION: Restoration of AV synchrony is possible in a substantial proportion of patients treated with long-term ventricular stimulation. Atrial lead placement through ipsilateral subclavian venipuncture is generally feasible, and the vast majority of cases remain in dual chamber pacing with normal function during intermediate term follow-up.

Submaximal early exercise test compared to clinical findings for evaluation of short- and long-term prognosis after the first myocardial infarction. Result from the MONICA Projects in Augsburg and Toulouse.

Clinical and ergometric data were derived from 1098 consecutive exercise tests in patients with a first acute myocardial infarction between 1974-1983. In 1992 a follow-up was performed in order to analyse the importance of a submaximal early exercise test, in combination with clinical data, for the prediction of short- and long-term prognosis of cardiovascular death. The relative value of 20 clinical variables, including medical history, markers of infarction size, medication etc., and 28 variables at exercise test were studied. Univariate, multivariate and survival analysis, for estimation of prognosis and independent prediction of cardiovascular death was used. Independent clinical risk factors for cardiovascular death were (1) Within 1 year: relative heart volume (ml.m-2 body surface area) on chest X-ray. (2) Long-term mortality: maximum heart rate and relative heart volume, diabetes, age and digitalis medication. Independent exercise risk factors were: (1) Within 1 year: heart rate, ventricular arrhythmia and ST depression > or = 1 mm before exercise, diastolic blood pressure at maximum exercise and target heart rate. (2) Long-term mortality: angina pectoris and/or ST depression > or = 1 mm at maximum exercise. In subgroups of patients with clinical risk factors, mortality risk increased if there were signs of angina pectoris and/or ST depression > or = 1 mm during exercise. The risk increased 100% in diabetics, 91% with age > 70 years, 58% with relative heart volume > or = 500 ml.m-2 body surface area, 42% with heart rate > or = 100 at admission, and 34% with digitalis medication. No increase was found in the subgroup of patients without clinical risk factors. Thus, submaximal early exercise stress testing provides important information for short- and long-term prognosis in patients after the first acute myocardial infarction compared to clinical evaluation alone.

Cardiovascular risk factors in commercial flight aircrew officers compared with those in the general population.

Cardiovascular disease is the most common reason for loss of license among commercial flight pilots. This study was done to explore cardiovascular risk factors among aircrew officers. The study group consisted of 113 male commercial flight aircrew officers (aviators), aged thirty-five to forty-four years (mean: 38.8 years) who participated in the compulsory health screening. Men investigated at the Health Screening Centre, Malmö, were used as the reference group. Group 1, for ECG, (n 771), aged thirty-eight to forty-four years (mean: 42.1). Group 2, for height, weight, body mass index (BMI) (weight kg/height m2), blood pressure, serum cholesterol (total), and smoking habits (n 5005), aged thirty-five to forty-four years (mean: 39.2). The aviators did not differ from the reference population in regard to height, weight, BMI, diastolic blood pressure, or smoking habits. However, the incidences of electrocardiographic left ventricular hypertrophy, increased systolic blood pressure, and the level of cholesterol were significantly higher in the aviators when compared with the controls. Aircrew members may primarily be selected by criteria that differ from the male population in general. Excessive environmental stress, ie, shift work, jet lag, fatigue, as well as dietary factors, may also contribute to anomalies in the group. The clinical consequences of these anomalies for the aviators should be further evaluated, for they are important both for the aviators and for flying safety.

Continuous vectorcardiographic changes in relation to scintigraphic signs of reperfusion in patients with acute myocardial infarction receiving thrombolytic therapy.

OBJECTIVES: Changes in the electrical activity of the heart reflecting the infarct process can be recorded by continuous vector-ECG, a method which is now clinically available for cardiac supervision. Shifts of the ST-segment and QRS-vector reflect ischaemia and necrosis of the myocardium. Continuous vector-ECG changes were evaluated against myocardial scintigraphy in 18 patients with acute myocardial infarction treated with streptokinase in order to study the impact of improved myocardial perfusion. DESIGN: Myocardial perfusion was analysed with 99Tcm-Sestamibi (Cardiolite, DuPont Scandinavia AB, Kista, Sweden) single photon emission computerized tomography (SPECT). Registrations were performed before and after thrombolysis in order to estimate the amount of myocardium with impaired perfusion initially (threatened myocardium) and the degree of perfusion improvement in this myocardial area. X, Y, Z vectors were registered continuously by Frank leads (Ortivus Medical, Täby, Sweden). QRS-vector difference, and the time to plateau phase and the ST-vector magnitude were used as a measurement of ischaemia and size of the myocardial infarction. RESULTS: In seven out of 11 patients treated within 3 h of onset of symptoms, an improvement in myocardial perfusion in the initially hypoperfused areas was achieved in contrast to none of the seven patients treated > 3 h after onset of pain (P < 0.05). In the whole patient material, there was a negative correlation between the time to plateau level for the QRS-vector and the improvement in myocardial perfusion (r = -0.53, P < 0.05). Among patients treated within 3 h, there was a negative correlation between the plateau level for the QRS-vector magnitude compared to the improvement in myocardial perfusion (r = -0.61, P < 0.05) and a negative correlation between the plateau level and the myocardial perfusion level after therapy (r = -0.69, P < 0.05). In these patients, there were also negative correlations between the maximal ST-vector magnitude and the myocardial perfusion both before and after thrombolysis (r = -0.81, P < 0.05 and r = -61, P < 0.05, respectively). CONCLUSION: Patients with marked improvement in myocardial perfusion indicating successful thrombolysis reach their plateau levels of the QRS-change faster and have lower total QRS-vector differences than patients without successful thrombolysis as reflected by myocardial scintigraphy. Patients with a high ST-vector magnitude have low perfusion levels both before and after therapy indicating a pronounced ischaemic damage of the myocardium. Thus, VCG-changes reflect impairment in myocardial perfusion during acute myocardial infarction.

Blood pressure and myocardial perfusion in hypertensive patients with and without left ventricular hypertrophy.

To evaluate the effect of acute blood pressure (BP) changes on the myocardial perfusion in hypertensives, 10 patients with and 10 patients without left ventricular hypertrophy (LVH) were examined with 99TCm-Sestamibi scintigraphy at rest and after acute pharmacological BP reduction using nifedipine and captopril. Signs of LV ischaemia was quantified as the size of the hypoperfused area defined as isotope uptake below 70% of maximum LV uptake, and LVH was defined as ventricular mass (LVM) > 125 g/m2 BSA by use of echocardiography. Not significant relations between BP and size of the hypoperfused area was found at rest. During BP reduction patients with LVH had negative correlations (r = -0.58) between the size of the hypoperfused area and the systolic blood pressure (SBP) and the diastolic blood pressure (DBP) (r = -0.49) while patients without LVH showed positive correlations (SBP r = 0.60, DBP r = 0.48). The differences in correlation coefficients were significant (P < 0.01) for both. Thus, in hypertensives with LVH, ischaemia may develop at low BP providing a possible mechanism for the observed increased risk of cardiovascular events in some hypertensive patients with low achieved BP during follow-up. Until treatment goals are defined on scientific grounds, BP should not be decreased below 90 mm Hg in subjects with LVH.

99Tcm-sestamibi uptake in the leg muscles and in the myocardium in patients with intermittent claudication.

99Tcm-Sestamibi has now replaced 201Tl as a cardiac imaging agent. In addition to the myocardial uptake there is also a considerable uptake in the striated muscle, which may be used for analyzing the muscular perfusion. Sixteen patients with intermittent claudication were investigated with 99Tcm-Sestamibi-SPECT (single photon emission computerized tomography) in order to visualize coronary ischemic disease. After the registration of the myocardial perfusion they were also studied regarding their leg muscle perfusion. This was done at rest and during standardized stress test using a bicycle ergometer. In 10 of the patients there was an increase in the isotope uptake in the myocardium from work to rest > 10% reflecting pronounced myocardial ischemia, which, however, was symptomatic in only 4 of the patients. The muscular uptake in the myocardium of 99Tcm-Sestamibi in the thigh increased significantly from rest to exercise (P < 0.01), while it remained unchanged in the calf muscle. There were no significant correlations at rest between the ratio of the right and left systolic blood pressure in the ankles and the ratio between the right and left isotope uptake in the calves, but the increase in the isotope uptake from rest to work correlated with the blood pressure ratio at r = 0.79, P < 0.01 (anterior projection) and r = 0.71, P < 0.01 (posterior projection).

Low blood pressure levels and signs of myocardial ischaemia: importance of left ventricular hypertrophy.

To clarify a possible relationship between the level of BP and signs of myocardial ischaemia, two groups of treated hypertensive patients with (n = 12) and without (n = 18) increased left ventricular mass defined by echocardiography were investigated with 24h ambulatory BP and ECG monitoring. It was found that hypertensive patients with increased left ventricular mass had the following. (1) Higher systolic BP, heart rate (HR) and SBP x HR product during the night indicating a higher ventricular work load than hypertensives without increased LVM in this period. (2) This increased left ventricular work load during the night was concomitant with a lower DBP consistent with a lower perfusion pressure of the left ventricular myocardium. (3) Significantly depressed ST segment levels throughout the 24 hours with a significant positive correlation between BP and the level of the ST segment indicating increased ischaemic metabolic changes within the myocardium the lower the BP. (4) A higher ratio between the systolic SBP x HR product and DBP during sleep than in hypertensives without increased left ventricular mass, further corroborating that low DBP during the night might cause ischaemia through an imbalance between left ventricular work load and coronary perfusion pressure. We conclude that low BPs in hypertensive patients with increased left ventricular mass seem to induce ischaemia of the left ventricle. These findings provide a possible mechanism for the increased risk of ischaemic heart disease in hypertensive patients with low achieved BP.

Myocardial reperfusion in thrombolysis A 99Tcm-Sestamibi SPECT study in patients with acute myocardial infarction.

This study presents the outcome of myocardial scintigraphy performed before and after thrombolytic treatment in 16 patients with acute myocardial infarction using 99Tcm-Sestamibi (Cardiolite, Du Pont Scandinavia AB, Kista, Sweden). The patients were given 99Tcm-Sestamibi intravenously as soon as possible after the decision to give thrombolytic treatment. When the patients were in a clinically stable state after the thrombolytic treatment, myocardial perfusion was analysed with the gamma camera using single photon emission computerized tomography (SPECT). A second 99Tcm-Sestamibi tomography was carried out on the second to fourth day after the myocardial infarction. Data reconstruction was done with the 'Bull's eye technique'. Nine patients received thrombolysis < 3 h from the onset of pain. In this group six patients (66%) improved their myocardial perfusion by > 10% after treatment, while all seven patients who received treatment > or = 3 h after the onset of pain improved their myocardial perfusion by < 10%. This study emphasises the importance of early diagnosis and treatment of patients with acute myocardial infarction in order to salvage myocardium.

Markers for development of hypertension in commercial flight aviators.

In order to discover markers for the development of cardiovascular disease and hypertension, we studied systolic and diastolic blood pressure, ECG, and heart rate before, during and after exercise; body mass index (BMI); serum cholesterol; and smoking habits in 183 male aviators (mean age 41 years at commencement, and 55 at follow-up). Those developing cardiovascular disease had an overrepresentation of smokers but the disease could not be related to any other variable. By contrast we found the following independent markers for prediction of future hypertension in normotensive aviators: increased BMI, increased diastolic blood pressure at 50 W, low heart rate at maximal exercise and smoking. Of these markers high diastolic blood pressure and low heart rate during exercise are new. Subjects with initially elevated blood pressure who did not develop hypertension decreased their diastolic blood pressure after exercise in contrast to those developing hypertension.

Effect of xamoterol on exercise capacity and left ventricular function in angina pectoris and in dilated cardiomyopathy.

The present study evaluates the effect of the beta 1 partial agonist xamoterol in patients with coronary artery disease compared to the effect in patients with dilated cardiomyopathy. Nineteen patients with angina pectoris and nine patients with dilated cardiomyopathy received xamoterol 200 mg b.i.d. for 4 weeks in a placebo-controlled double-blind study. The effect was evaluated with a standardized exercise test and radionuclide angiocardiography with determination of global and regional ejection fraction. At rest xamoterol caused no significant changes among the angina patients while global and regional ejection fraction increased among the cardiomyopathy patients. During exercise, when the drug exerts a beta 1-antagonist effect, xamoterol increased the exercise performance among the angina pectoris patients. Fourteen out of 19 patients with angina pectoris were unable to increase their ejection fraction from rest to work due to coronary ischaemia. These 14 patients improved their global ejection fraction during work after xamoterol treatment.

Serum CK-MB is useful in diagnosis of acute myocardial infarction after total hip arthroplasty.

Skeletal muscle trauma and myocardial infarction both increase the serum values of the creatine kinase isoenzyme MB (CK-MB) which may render the diagnosis of perioperative myocardial infarction in major orthopaedic surgery more difficult. The significance of postoperative changes in CK-MB was studied in 30 patients subjected to total hip replacement (THR), and the results were compared to CK-MB in 30 nonsurgical patients with acute myocardial infarction (AMI). AMI patients had significantly higher serum CK-MB values at 24 h than THR patients. However, the highest value after THR exceeded the lowest value in AMI. The results suggest that skeletal muscle release of CK-MB after THR is slight. CK-MB thus also seems useful in the diagnosis of AMI in postoperative patients.

The effect of oral diltiazem on left ventricular performance in postinfarction patients.

The purpose of the present study was to evaluate the effect of diltiazem on the left ventricular function in postinfarction patients. Twelve patients without cardiac decompensation at rest began diltiazem therapy beginning 3 months after an acute myocardial Q-wave infarction. Oral diltiazem was administered on the first day in a single dose (120 mg) and the following 2 weeks in a 60 mg three times a day (tid) regimen. The therapeutic effect was studied by isotope angiocardiography at rest using equilibrium measurements with technetium-99m. Acute as well as continuous treatment improved left ventricular function in terms of increased synergy of the contraction (decreased phase deviation from a median of 20.0 degrees to median of 12.4 degrees and 13.0 degrees, respectively, p less than 0.01) and increased ejection fraction from a median of 46% to a median of 50% and 51%, respectively, p less than 0.05. It is suggested that the improvement of left ventricular function may be due in part to decreased pressure rate product. This improved left ventricular function during diltiazem treatment may explain the improved prognosis induced by diltiazem in postinfarction patients.

Measurement of global and regional left ventricular performance with isotope technique in coronary heart disease.

In order to evaluate the left ventricular function in coronary artery disease, radionuclide measurements of global and regional ejection fraction (EF), regional wall motion and phase analyses of the left ventricular contraction were performed by equilibrium technique. One group of patients with angina pectoris and one group with myocardial infarction were compared with a control group. All the above-mentioned parameters significantly separated the infarction group from the reference group both at rest and during work, while the group of patients with angina pectoris showed disturbances mainly during work, such as impaired ability to increase global and regional ejection fraction and regional wall motion. Adding regional analysis and phase analysis to the global EF determination increases the possibility of studying the left ventricular function. However, this addition has a limited value in detecting impaired left ventricular function compared to the determination of just global EF in patients with angina pectoris and in patients with myocardial infarction.

Hemodynamic effects of metoprolol and nifedipine in angina pectoris measured by isotope technique.

In order to evaluate the therapeutic effects of metoprolol, nifedipine, and their combination, 11 patients with secondary angina pectoris and with thallium tomographic findings indicating coronary artery disease were studied before and after these three treatment regimes in a single-blind cross-over study. The therapeutic effect was measured by standardized working test and isotope angiocardiography, which enabled evaluation of left ventricular ejection fraction, stroke volume, and phase analysis of left ventricular contraction. Treatment with metoprolol and combination therapy increased work performance. Ejection fraction did not differentiate the treatment regimes, whereas stroke volume was significantly lower at work and heart rate higher at rest and at work during nifedipine treatment compared to either metoprolol or combination treatment (p less than 0.05). Cardiac output was significantly reduced during nifedipine and metoprolol treatment during work (p less than 0.05). Phase improved after all therapeutic regimes, but reached significance only during the metoprolol treatment period at rest (p less than 0.05).

The effect of atenolol on the left ventricular performance in patients with angina pectoris measured with isotope technique.

Working capacity, left ventricular ejection fraction (EF), stroke volume and the phase of the left ventricular contraction were tested before and after 3 weeks of atenolol treatment in 14 patients with angina pectoris and coronary insufficiency diagnosed by thallium tomography. Eight patients (group A) increased their EF during exercise and six patients (group B) showed a decrease in EF when tested with placebo. When treated with atenolol the changes in EF during exercise were reversed in the two groups. Group B increased and group A decreased their EF. Atenolol caused an increase in working capacity in group B, but not in group A. In both groups atenolol caused an increased stroke volume and a decreased phase deviation at rest, while no significant volume changes or phase changes occurred during exercise. These results indicate that atenolol treatment had the most marked effect in patients with the most pronounced disease.

Radionuclide left ventricular volume determination. Influence of scattered radiation and surrounding activity.

Radionuclide measurements of left ventricular volumes, ejection fractions and stroke volumes were performed by an equilibrium technique in nine patients using left anterior oblique projection and individual depth correction. Phantom studies were made in order to evaluate attenuation and scattering of the radiation. It was found that a simple depth correction factor, k(d) = e mu d, can be used under certain conditions. However, the determination of left ventricular volume by radionuclide techniques is not a truly absolute method. The depth correction factor to be used is dependent on the condition of measuring and evaluation, for instance how the region of interest for the left ventricle is selected. Therefore, this method should be carefully standardized, evaluated and compared to other techniques. Stroke volume measured by radionuclide and dye-dilution technique showed a correlation coefficient of 0.76 (nine patients) at rest and 0.77 (seven patients) at work. This method can be easily performed during routine ejection fraction determination and can thus be useful in clinical studies.