[New year, new home].
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Biomedical subjects
Publications and source records attributed to A J Dunning.
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In patients after cardiac surgery, hypotension, defined as a mean arterial pressure less than 65 mmHg despite adequate filling pressures and positive inotropic medication, poses a problem. In addition, it is often difficult to determine whether these patients have suffered irreversible myocardial injury or if they are likely to recover. In this study, left and right ventricular function, as assessed by transesophageal echocardiography (TEE), was related to mortality both (1) quantitatively, using fractional area change (FAC), and (2) qualitatively, using a segmental wall motion analysis, which assigned a score to myocardial wall segments, in order to determine whether this technique can be used to predict survival. Mortality rate was very high in patients with biventricular and especially right ventricular failure (FAC less than 35%). Left and right ventricular wall motion abnormality indices were significantly better in survivors compared to nonsurvivors, but no distinct cut-off value could be determined. A wall motion index derived from only 6 segments at the mid-papillary muscle level was found to be as reliable as one based on 16 segments of the entire left ventricle. Thus, TEE provided information about the degree of left and right ventricular dysfunction by using a single cross-section at the papillary muscle level. It identified patients at high risk of death, ie, those with compromised right and biventricular function.
As regional wall motion abnormality (RWA) is the first sign of ischaemia, transoesophageal echocardiography was evaluated as a monitoring device in 51 patients undergoing abdominal aortic surgery. Wall motion of the entire left ventricular wall (nine segments) was semiquantitatively evaluated 15 min before and after aortic cross-clamping and 3 h after declamping. In addition, limb lead II of the electrocardiogram was simultaneously recorded. At baseline, RWA was present in 16 patients (31%). New or worsened RWA 15 min after aortic cross-clamping was seen in 17 patients, of whom 11 had persistent RWA, i.e. it was still present 3 h after declamping. This was associated in seven patients with enzymatically documented myocardial infarction. Only one infarct patient demonstrated ST segment changes of more than 1 mm. Thus, a single electrocardiographic surface lead is insensitive for perioperative myocardial ischaemia detection. Furthermore, new and/or worsened RWA after aortic cross-clamping, which persists until 3 h after declamping, is, to a considerable degree, associated with perioperative infarction.
To improve electrocardiographic localization of the site of origin of ectopic left ventricular (LV) impulse formation in the heart with prior myocardial infarction, 62-lead body surface QRS integral maps were studied during LV pacing at a total of 221 endocardial sites in 14 patients with previous anterior (AMI), inferior (IMI), lateral (LMI), or anterior and inferior (AMI/IMI) myocardial infarction. The anatomic location of each pacing site was computed using digitized biplane fluoroscopic images and plotted on standardized LV endocardial polar projections. A data base of characteristic AMI and IMI mean QRS integral maps was developed after visually selecting subgroups with nearly identical QRS integral morphology from the ectopic activation sequences produced at 110 sites in eight patients with AMI and at 66 sites in four patients with IMI. Intrasubgroup pattern uniformity and intersubgroup pattern variability were statistically verified. The endocardial pacing site locations belonging to each AMI and IMI subgroup were depicted as segments on the respective LV polar projections. In patients with AMI, a total of 18 typical mean QRS integral patterns were obtained, whereas 22 different mean total QRS integral patterns showing more substantial intersubgroup variation were acquired in patients with IMI. Posterolateral regions exhibited a relatively low electrocardiographic sensitivity (six AMI and five IMI patterns) as compared with anteroseptal regions (12 AMI and 17 IMI patterns). Total QRS integral patterns obtained at 24 sites in one patient with LMI were largely compatible with the IMI mean total QRS integral patterns, whereas the majority of total QRS integral patterns acquired at 21 sites in one patient with AMI/IMI corresponded with the AMI mean total QRS integral patterns. The results show that total body surface QRS integral maps generated during LV pacing in patients with prior myocardial infarction cluster by pattern and that each QRS integral pattern is related to a circumscribed endocardial segment of ectopic impulse formation. The relation between a given QRS integral pattern and the position and size of the corresponding paced segment is dependent on infarct location. The present infarct-specific data base of characteristic total body surface QRS integral patterns provides a clinical tool to obtain detailed electrocardiographic localization of ventricular arrhythmias in patients with previous myocardial infarction.
Because it is sometimes difficult to determine the cause of hypotension in patients after cardiac operations, we assessed the value of transesophageal echocardiography in this respect, and we studied 60 consecutive patients who had hypotension despite positive inotropic medication and, in some patients, mechanical support. Echocardiographic diagnoses were compared with diagnoses based on hemodynamic parameters. Follow-up examinations were completed in all patients to confirm the final diagnoses. Echocardiographic signs of hypovolemia were present in 14 patients, tamponade in six, left ventricular failure in 16, right ventricular failure in 11, and biventricular failure in eight. Echocardiographic examination proved to be inconclusive in five patients. Comparison with hemodynamic parameters showed agreement on diagnoses (hypovolemia versus tamponade versus cardiac failure) in 30 patients (50%). Echocardiography correctly identified two patients with tamponade and six with hypovolemia; these conditions were not suspected by standard hemodynamic data; in five patients unnecessary reoperation was prevented, although hemodynamic values were suggestive of tamponade. Echocardiography also identified subcategories of patients at high risk of death (those with signs of right ventricular and biventricular failure). These findings suggest that transesophageal echocardiography performed on patients after cardiac operations, at the bedside in the intensive care unit, can readily elucidate the cause of hypotension in the large majority of patients and is a valuable adjunct to hemodynamic evaluation in patient management. Furthermore, it appears to be possible to identify subcategories of high-risk patients, based on these echocardiographic findings.
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To determine the factors that influence the presence of collateral vessels during coronary occlusion, we performed standardized contrast injection of the contralateral coronary artery in 58 consecutive patients, without previous myocardial infarction, undergoing percutaneous transluminal coronary angioplasty for 1-vessel disease (left anterior descending artery in 45, right coronary artery: in 10 and left circumflex artery in 3). The presence of collateral vessels during coronary occlusion, defined as partial or complete epicardial opacification by collateral vessels of the vessel dilated, was related to clinical, angiographic and electrocardiographic parameters. The angiographic appearance of collateral vessels during balloon inflation showed a weak, although statistically significant, correlation to the percent diameter stenosis before angioplasty (r = 0.28; p = 0.03) and the duration of angina (r = 0.37; p = 0.004). By combining lesion severity with the duration of angina, collateral vessels during coronary occlusion were particularly related to a lesion severity greater than or equal to 70% and duration of angina greater than or equal to 3 months (p less than 0.001). Furthermore, the presence of collateral vessels was associated with an absence of ST-segment shift (greater than or equal to 1 mm) during 1 minute of coronary occlusion (p less than 0.001).
To determine the clinical outcome and the long-term results of a second coronary artery bypass operation, we studied preoperative clinical status and catheterization data in 200 consecutive patients over a 9-year period (1979 to 1987) (mean follow up time 34 months, maximum 120). The study group included 169 men and 31 women (mean age 58.4 years [7% greater than 70 years]). Sixty-four percent of patients had severe angina (New York Heart Association class IV), 70% had 3-vessel coronary artery disease and 21% had poor left ventricular function. Reoperation was performed after a mean interval of 58 months after the first procedure. A mean of 3.3 distal anastomoses was placed. The operative mortality rate (30 days) was 7.5%, with additional cardiac morbidity (myocardial infarction, heart failure) in 11.5% of patients. Multivariate analysis showed an increased risk in women (risk ratio 3.6) and in patients with poor left ventricular function (risk ratio 3.1). The cumulative 5-year survival rate was estimated at 84%, with a rate of 77% for patients with poor left ventricular function (difference not significant). The probability of remaining free of a cardiac-related event (myocardial infarction, angioplasty, third operation, cardiac death) was 64% for 5 years. At the end of follow-up, 79% of the surviving patients were in New York Heart Association class I or II and nearly 50% of patients in the fifth year after the reoperation had good functional status. It is concluded that a reoperation is effective but carries an increased, immediate, operative risk.(ABSTRACT TRUNCATED AT 250 WORDS)
A balloon catheter with six electrodes has been developed for transesophageal atrial stimulation of the human heart. Introduction is easy and its positioning is simple with the help of six unipolar atrial electrograms. In a group of 20 healthy volunteers, stimulation and discomfort thresholds (intolerable discomfort) were measured for three levels of pulse widths (12, 16, and 20 msec) and for five electrode configurations. Stimulation thresholds were below discomfort thresholds in each case. The stimulation threshold depended on pulse width and not on electrode configuration. The discomfort threshold, however, depended on the electrode configuration and not on the pulse width. A moderate but potentially important increase of the ratio between stimulation threshold and discomfort threshold could be achieved by combining a long pulse width (20 msec) and avoiding the largest distance between the active (cathode) and the passive (anode) electrode. Transesophageal atrial stimulation promises to be a practical noninvasive tool for the termination of regular supraventricular tachycardias, basal electrophysiological studies, and controlled acceleration of the heart rate in the study of myocardial ischemia.
The reported incidence of myocardial damage after coronary artery bypass grafting (CABG) is highly related to the methods used. Since indium-111 monoclonal antimyosin antibody scintigraphy has been shown to be highly specific and sensitive for myocardial necrosis, even in small lesions, uptake of this radiotracer was evaluated after CABG. In 23 consecutive patients without previous myocardial infarction who underwent CABG for stable angina, 80 MBq indium-111 antimyosin was injected on the third postoperative day. Planar images were obtained 48 hours later and analyzed for myocardial uptake of indium-111 antimyosin. Scintigraphic results were related to creatine kinase MB levels, duration of both aortic cross-clamping and cardiopulmonary bypass, and electrocardiographic changes. In all patients surgical procedure and postoperative course was uncomplicated. Indium-111 antimyosin uptake was present in 19 of 23 patients (82%). It was diffused in 7 patients and localized in 12. No pathologic Q waves occurred postoperatively. Fourteen patients exhibited ST-segment changes. No good relation was found among indium-111 antimyosin uptake and creatine kinase MB levels, duration of cross-clamping or bypass, and ST-T changes. It is concluded that some degree of myocardial damage, though silent, is common after CABG.
The clinical course of the first six weeks after discharge after consultation was studied in 527 patient contacts in 460 patients who were evaluated for acute cardiac symptoms in a six-month period at the acute cardiac care facility 'Eerste Harthulp' in the Academic Medical Centre. Analysis revealed that the initial diagnosis of acute ischaemia (261 cases) was correct in 118 (45%) and the initial diagnosis of arrhythmia (114 cases) in 92 (81%). In 220 patients there was no cardiac history; in those instances the initial diagnosis of acute ischaemia was confirmed in only 40% but the initial diagnosis of arrhythmia in 78%. Three patients died within six weeks after evaluation and 28 patients were admitted within that period. Patients without cardiac history and without a clear cardiac diagnosis consulted their general practitioner moderately frequently in the first six weeks and used specialist care only rarely.
OBJECTIVE: To determine the long term effects of relaxation therapy on 24 hour ambulatory intra-arterial blood pressure in patients with mild untreated and uncomplicated hypertension. DESIGN: Four week screening period followed by randomisation to receive either relaxation therapy or non-specific counselling for one year. Ambulatory intra-arterial blood pressure was measured before and after treatment. SETTING: Outpatient clinic in Amsterdam's university hospital. SUBJECTS: 35 Subjects aged 20-60 who were being treated by general practitioners for hypertension but were referred to take part in the study. At three consecutive screening visits all subjects had a diastolic blood pressure without treatment of 95-110 mm Hg. Subjects were excluded if they had damaged target organs, secondary hypertension, diabetes mellitus, a cholesterol concentration greater than 8 mmol/l, or a history of malignant hypertension. INTERVENTIONS: The group allocated to relaxation therapy was trained for eight weeks (one hour a week) in muscle relaxation, yoga exercises, and stress management and continued exercising twice daily for one year with monthly visits to the clinic. The control group had the same attendance schedule but had no training and were requested just to sit and relax twice a day. All subjects were asked not to change their diet or physical activity. MAIN OUTCOME MEASURE: Changes in ambulatory intra-arterial blood pressure after one year of relaxation therapy or non-specific counselling. RESULTS: Mean urinary sodium excretion, serum concentration of cholesterol, and body weight did not change in either group. Diastolic pressures measured by sphygmomanometry were 2 and 3 mm Hg lower in subjects in the relaxation group and control group respectively at the one year follow up compared with initial readings. The mean diastolic ambulatory intra-arterial pressure during the daytime had not changed after one year in either group, but small treatment effects could not be excluded: the mean change for the relaxation group was -1 mm Hg (95% confidence interval -6 to 3.9 mm Hg) and for the control group -0.4 mm Hg (-5.3 to 4.6 mm Hg). Mean ambulatory pressure in the evening also had not changed over the year, and in both groups nighttime pressure was 5 mm Hg higher. The variability in blood pressure was the same at both measurements. CONCLUSIONS: Relaxation therapy was an ineffective method of lowering 24 hour blood pressure, being no more beneficial than non-specific advice, support, and reassurance--themselves ineffective as a treatment for hypertension.
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The invasion of technology, both in society and health care, asks for critical assessment of efficacy and safety. In a greying population hospital care will be substituted by home care in the treatment of chronic diseases. Continuity of care, between hospital and home, requires good communication between physician, patient and family. The hospital pharmacy has an essential role in providing treatment material in renal dialysis, chemotherapy or parenteral nutrition, the instruction of patients and the quality control of diagnostic tests and new devices for drug administration. The surveillance of complex medication, especially in the elderly, is an important part of that consultancy. The hospital pharmacist, in order to take up his place in the treatment team, should become familiar with new and technical aspects of drug administration in home care setting and the safety of its transfer from hospital to home.
Fifty patients with severe symptomatic aortic stenosis underwent a balloon valvuloplasty of the aortic valve with acceptable initial haemodynamic results. Follow-up at one month showed clinical improvement in 66% of the patients. Long-term follow-up (clinical, Doppler echocardiography and repeat cardiac catheterization) was disappointing. The intervention-free rates at one and two years were 44% and 26%, respectively. Aortic balloon valvuloplasty should be limited to patients with a severe aortic stenosis and short life expectancy because of non-cardiac disease and to patients with severely depressed left ventricular function as a bridge to valve replacement.
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To assess the relation between early Indium-111 monoclonal antimyosin antibody scintigraphy and degree of regional asynergy on discharge, 38 patients with a first acute myocardial infarct were studied (18 anterior, 20 inferoposterior infarctions). In 21 patients thrombolytic therapy was administered. On the first day of myocardial infarction, 80 MBq Indium-111 Antimyosin was injected. Planar images, anterior, lateral and left anterior oblique, were made 24 hours later. Localized myocardial uptake was present in 37/38 patients, and was evaluated for Count Density Index (count density of infarct zone/left lung count density) in the left anterior oblique images, which displayed the infarct zone well. Regional asynergy on discharge was evaluated by cross-sectional echocardiography and defined mild (hypokinesia) or severe (akinesia or dyskinesia). Count density index was significantly lower in 15 patients with mild asynergy, compared with 22 patients with severe asynergy (1.61 +/- 0.25 vs. 2.42 +/- 0.40, p less than 0.001). This difference was present in both patient groups treated with or without thrombolysis. We conclude that early count density index, reflecting the amount of local necrosis, is highly correlated to the ultimate degree of wall motion impairment.