Biomedical subjects

D Burckhardt

Publications and source records attributed to D Burckhardt.

At least 19 recordsLinked to original sources

PubMed1992

[Ischemic cerebrovascular seizure: when and how should one search for a cardiac embolism source?].

Cerebral embolism originating from the heart accounts for approximately 15 to 20% of ischemic strokes. By far the most important source for cardiac embolism is associated with atrial fibrillation; in these patients immediate anticoagulation with no further echocardiographic diagnostic is recommended. The majority of the remaining cardiac sources of embolism--they originate from the left ventricle and the valves--can be suggested by clinical signs. In these cases a documentation by echocardiography is indicated. In contrast, embolism originating from the left atrium is rare and commonly not detectable by simple clinical means. The semi-invasive transesophageal echocardiography is able to visualize atrial pathologies with a high accuracy, but this investigation should be performed routinely only in patients less than 45 years old with no evidence for cardiac disease.

Atrial Fibrillation↗

PubMed1992

[Heart valve substitution: the effect of preoperative findings on long-term outcome].

BACKGROUND: In a retrospective analysis of 653 consecutive patients who underwent heart valve replacement by one single type of mechanical prosthesis (St. Jude Medical) at three Swiss university medical centers (Basel, Bern, Lausanne), the outcome was judged on the basis of preoperative variables. These variables should facilitate the timing of heart valve replacement. METHODS: Preoperative evaluation includes NYHA classification of symptoms, chest X-ray, ECG, and LVEF on angiography. Postoperative outcome was assessed clinically at yearly intervals by NYHA classification, documentation of complications and mortality. RESULTS: Five-year-survival rates were 96 and 88%, and complication-free rates were 82 and 76% respectively in patients after isolated aortic and mitral valve replacement. An unsatisfactory outcome with death or persistent severe symptoms was more frequent when preoperative symptoms at rest and atrial fibrillation were present. CONCLUSION: Heart valve replacement should not be postponed until severe symptoms and functional impairment occur. Clinical criteria are at least as important for the timing of operation as the findings of more complex investigations.

Adolescent↗

PubMed1992

[Transesophageal echocardiography: technique, indications and findings].

The introduction of transesophageal echocardiography (TEE) as a 'semi-invasive' technique with few complications in clinical practice represents a major diagnostic advance in the evaluation of cardiac disease. The close anatomic vicinity of the transducer to the heart and thoracic aorta allows the use of high frequency devices with better resolution compared to transthoracic echocardiography. Furthermore, the diagnostic gain when evaluating structures that are poorly visualized by the transthoracic approach such as the left atrial appendage, interatrial septum, prosthetic valves and the thoracic aorta is highly improved by TEE. Major indications for TEE include the search for a cardiac source of embolism and cardiac tumors, the work-up prior to balloon mitral valvuloplasty, the evaluation of prosthetic valves and the search for vegetations and aortic dissection. After a short summary of patient preparation, instrumentation and examination technique, the major indications, contraindications and complications are reviewed on the basis of our own experience and the literature.

Aortic Dissection↗

PubMed1992

Beneficial effect of amiodarone on cardiac mortality in patients with asymptomatic complex ventricular arrhythmias after acute myocardial infarction and preserved but not impaired left ventricular function.

To determine whether the beneficial effect of low-dose amiodarone on survival in patients with complex ventricular arrhythmias after myocardial infarction was dependent on left ventricular (LV) function, results of the Basel Antiarrhythmic Study of Infarct Survival were analyzed. Two hundred twelve patients after acute myocardial infarction with asymptomatic complex arrhythmias were randomly assigned to receive amiodarone 200 mg/day or to a control group and followed up for 1 year. Results of mortality and arrhythmic events were related to baseline radionuclide LV ejection fraction. With preserved (greater than or equal to 40%) LV ejection fraction, there was a significantly lower 1-year cardiac mortality in patients treated with amiodarone (1 of 68 or 1.5%) versus control subjects (5 of 56 or 8.9%; p less than 0.03). This was not the case for patients with LV ejection fraction less than 40%. Similarly, arrhythmic events were significantly reduced only in patients with preserved LV function. These results suggest an interaction between the effects of amiodarone on survival and LV dysfunction in patients after acute myocardial infarction. Because of 2 other small studies with similar results, this finding may be of clinical relevance and should be addressed in ongoing and future research with this drug.

Aged↗

PubMed1992

Spectrum of subclinical and overt hypothyroidism: effect on thyrotropin, prolactin, and thyroid reserve, and metabolic impact on peripheral target tissues.

PURPOSE: Subclinical hypothyroidism is found in about 7.5% of females and in about 3% of males. It appears to be a risk factor for atherosclerosis and for coronary heart disease and can affect various other target organs. The morbidity and clinical significance of subclinical hypothyroidism are controversial. Therefore, we evaluated the metabolic impact of progressive thyroid failure in patients with various degrees of hypothyroidism compared with control subjects. PATIENTS AND METHODS: We investigated 86 female patients with the whole spectrum of subclinical hypothyroidism (n = 69) and of overt hypothyroidism (n = 17) and 52 euthyroid women as controls. All subjects underwent full medical and endocrine evaluations (including measurements of thyrotropin [TSH], TSH beta- and alpha-subunits, and prolactin before and after oral administration of thyrotropin-releasing hormone [TRH]) as well as lipid profiles and different tests of peripheral thyroid hormone action. All hypothyroid patients were divided into five categories according to disease severity: grades I to III (subclinical hypothyroidism, with normal thyroxine [T4] levels) and grades IV and V (overt hypothyroidism, with diminished T4). RESULTS: In grade I subclinical hypothyroidism (basal TSH below 6 mU/L), we found significant changes in the clinical index (p less than 0.05), apoprotein A-I level (p less than 0.05), and stimulated prolactin level after oral TRH (p less than 0.001). The findings were similar in grade II (TSH 6 to 12 mU/L). Further changes could be demonstrated in grade III (TSH above 12 mU/L) with a definite elevation of ankle reflex time (p less than 0.001), serum myoglobin level (p less than 0.01), and, to a lesser extent, creatine kinase (p greater than 0.1). The mean low-density lipoprotein cholesterol (LDL-C) level showed an increase of 18%, which was not significant because of marked individual variations (p = 0.15). The frequency of elevated LDL-C levels was definitely higher in patients with grade III disease compared with the controls (42.9% versus 11.4%, p less than 0.05) and with patients with grades I and II disease. Total cholesterol, triglycerides, apoprotein B, and the systolic time intervals (pre-ejection period, corrected for heart rate [PEPc]) were clearly elevated only in overt hypothyroidism (grades IV and V) (p less than 0.01). CONCLUSION: Subclinical hypothyroidism has significant effects on some peripheral target organs at an early stage (grades I and II), but affects LDL-C, skeletal muscle, and myocardial contractility only at a later stage (grades III, IV, and V). Our data of elevated LDL-C in grade III subclinical hypothyroidism provide a likely pathophysiologic explanation for the reported association of coronary heart disease with this syndrome. The impact of increased prolactin secretion, observed in subclinical hypothyroidism, on gonadal function and infertility has yet to be clarified. Therapy with thyroxine should be recommended in at least some patients with subclinical hypothyroidism. Patients with high TSH levels (above 12 mU/L) will require treatment because of the metabolic effects on several target organs. Before treatment is advocated in all patients with subclinical hypothyroidism, the benefits and long-term side effects of thyroid hormone therapy should be clarified by prospective studies in larger groups of patients.

Administration, Oral↗

PubMed1992

Doppler sonographic evaluation of mechanical and bioprosthetic mitral valve prostheses during exercise with a rate corrected pressure half time.

OBJECTIVE: To compare the effect of exercise on pressure half time in patients with mechanical or bioprosthetic mitral valves. A relative pressure half time (pressure half time as a percentage of RR interval) was used in an attempt to correct for the shortening of the diastolic time interval caused by the increase in heart rate during exercise and thus to uncover the effects of valve design on pressure half time during exercise. PATIENTS: Twenty clinically stable (New York Heart Association grade I-II) patients with mechanical (n = 12) or bioprosthetic (n = 8) mitral valves (median age 51) years. The median time since valve replacement was 42 months. METHODS: Continuous wave Doppler echocardiography from the apical view at rest and during moderate supine bicycle exercise (50 W). RESULTS: During exercise the mean (SD) heart rate increased from 79 (12) to 101 (12) beats per minute (95% confidence interval (95% CI) of difference, 15 to 29/min) and the peak pressure gradient from 11 (5) to 18 (6) mm Hg (95% CI of difference 5 to 9 mm Hg). The pressure half time decreased from 114 (30) to 78 (26) ms (95% CI of difference (30-42 ms). There was no difference between the valve types. The relative pressure half time remained unchanged in patients with mechanical valves during exercise (13 (4) rest and 13 (5)% exercise, respectively) and decreased in patients with bioprostheses (17 (3) and 12 (3)%, respectively (95% CI of difference 2 to 8%, p = 0.025). CONCLUSIONS: In patients with mechanical mitral valves the decrease in the pressure half time during exercise is probably mostly the result of the shortening of the diastolic time interval with increasing heart rate whereas in patients with bioprosthetic valves an increase in functional valve area may contribute to the shortening of pressure half time during exercise.

Adult↗

PubMed1992

Clinical efficacy of long-term treatment with amiodarone for life-threatening arrhythmias.

The present article reviews the experience with amiodarone therapy in life-threatening ventricular tachyarrhythmias. In 13 studies, 1,594 patients were treated with amiodarone in average doses of 300 mg/day. The mean annual death rate was 6.2%; the annual withdrawal rate averaged 8%. Risk factors for arrhythmia recurrence despite amiodarone therapy were low left ventricular ejection fraction, inducible ventricular tachycardia by programmed electrical stimulation or persisting ventricular tachycardia on Holter monitoring, and cardiac arrest before the institution of amiodarone therapy. In these patients, additional antiarrhythmic measures such as an automatic implantable cardioverter/defibrillator or other surgical interventions must be considered.

Amiodarone↗

PubMed1992

Influence of different pressure gradients on late clinical outcome after aortic valve replacement.

Late outcome vs. hemodynamic parameters were assessed and compared in a series of 44 patients followed for 10-17 years after aortic valve replacement either with a Starr-Edwards A 1260 (SE) or a Bjork-Shiley 60 degrees (BS) prosthesis. The two groups, 22 patients each, were selected by computer from the data base SG as to be matched for age, sex, underlying lesion, date of implantation, valve size, left ventricular function, and concomitant coronary artery disease. There was no significant difference in mortality and complication rates. Clinical evaluation at a mean of 12.5 +/- 2.2 years postoperatively revealed identical findings of heart size on chest X-rays (CTR 0.50 +/- 0.04 SE vs. 0.50 +/- 0.05 BS) and nearly identical incidence of left ventricular hypertrophy on the ECG (2/22 SE and 1/22 BS). There was a statistically significant difference in Doppler ultrasonic peak pressure gradients between the two valve types (SE 32 +/- 15 mmHg, BS 23 +/- 9 mmHg; p = 0.047), and of fractional shortening on M-mode echocardiograms (SE 30 +/- 9%, BS 37 +/- 8%, p = 0.038), but this was not reflected by a difference in the symptomatic status of the two groups. It is concluded, that in two groups of patients surviving 10-17 years after isolated aortic valve replacement with SE or BS valves, the statistically significant nine mmHg difference in gradient across the two valve types had no effect on long-term clinical outcome.

Aortic Valve↗

PubMed1992

[Drug prevention and therapy of ventricular tachycardia].

Antiarrhythmic drugs of type I to IV (Vaughan Williams) are generally used for the treatment of ventricular tachycardia, especially in patients with symptomatic and hemodynamically not tolerated arrhythmias; however, randomized controlled studies revealed a beneficial effect on sudden cardiac death only for type-II (beta-blocking agents) and type-III (Amiodarone) antiarrhythmic drugs. These drugs are, therefore, the antiarrhythmic agents of first choice; but, in addition, underlying heart disease, triggering factors and heart-rate dependency should be considered.

Anti-Arrhythmia Agents↗

PubMed1991

[Hemodynamics of various heart valve prostheses].

Modern tilting disc and bileaflet prostheses, and bio-prostheses, perform similarly regarding pressure gradients, discharge coefficient and performance index; however, only bio-prostheses increase their opening area with increasing flow. Ball valve prostheses of the Starr-Edwards type perform less satisfactorily with higher pressure gradients and lower performance indices, which may result in less favorable long-term follow-up. Bio-prostheses show degenerative changes with increasing age which, over a period of 7-10 years, can lead to clinically relevant stenoses necessitating reoperation.

Bioprosthesis↗

PubMed1991

Long-term treatment of ventricular tachycardia with amiodarone in presence of severe left ventricular dysfunction.

A group of 34 consecutive patients with coronary artery disease (n = 29) or dilated cardiomyopathy (n = 5) (3 women, 31 men, age 38-80 yr) who had severely impaired left ventricular function (left ventricular ejection fraction less than or equal to 40%) and high-grade ventricular ectopic activity (sustained or nonsustained ventricular tachycardia or ventricular fibrillation) were treated with amiodarone (mean dose: 206 mg/d) and followed for 1-117 (mean: 49) months. In the total group, there were seven sudden deaths, five deaths due to pump failure, one non-cardiac death, and two successful heart transplantations during follow-up. Thus the annual cardiac mortality in these carefully selected and followed patients was 8, 6%, the annual cardiac event rate was 10, 1%. The cumulative cardiac survival-rate was 62% after 5 years and 41% after 10 years. In five patients, treatment was interrupted after 10 to 43 months, three of the patients were alive at follow-up and two suffered cardiac death, resulting in an annual cardiac death rate of 12% in this subgroup of treatment. Based on the results of this retrospective analysis we conclude that in patients with low left ventricular ejection fraction and nonsustained or sustained ventricular tachycardia treated with low dose amiodarone, mortality was unexpectedly low. Thus, it may be the antiarrhythmic treatment to be considered in patients with ventricular tachycardia and severe left ventricular dysfunction.

Adult↗

PubMed1991

Treatment of mitral stenosis.

In patients with mitral stenosis the need for therapeutic intervention can be assessed by clinical and non-invasive data. Mitral valve replacement is indicated when marked dyspnoea on mild exertion, dyspnoea at rest or pulmonary oedema, haemoptysis, atrial fibrillation, recurrent systemic emboli or right ventricular failure occur in a patient with a mitral valve area of less than 1.5 cm2, as measured by Doppler echocardiography. This treatment will entail life-long anticoagulation in the majority of patients. Closed commissurotomy is no longer considered a valid therapeutic alternative due to its limited success rate but open commissurotomy and balloon valvotomy may be performed in patients with no significant calcification of valve cusps and no major concomitant mitral regurgitation. Preservation of the subvalvular apparatus and left ventricular geometry can be considered the most important advantages of these techniques. More severe chronic symptoms are generally required as indication for mitral valve replacement because of the additional long-term imponderabilities imposed by an implanted artificial device. Therefore, in patients with mitral stenosis different symptoms and clinical findings will eventually lead to different interventions.

Catheterization↗

PubMed1991

Effect of antiarrhythmic therapy on mortality after myocardial infarction.

In an attempt to improve survival of patients with coronary artery disease and high-grade ventricular ectopic activity, several studies using different antiarrhythmic drugs were undertaken. A meta-analysis of all randomized controlled trials using type I antiarrhythmic agents showed that the treatment effect was much more likely to be adverse than beneficial. In contrast to these studies, the pooled results of major secondary prevention trials using beta-blocking agents could demonstrate a significant reduction in the sudden death rate by an average of 24% during observation periods of 9-36 months. In the beta-blocker trials, however, patients with contraindications for this type of drug, such as overt congestive heart failure or chronic obstructive lung disease, were excluded. In these patients a type III antiarrhythmic drug, such as amiodarone, may have a place, and in fact, the Basel Antiarrhythmic Study of Infarct Survival, a prospective, controlled, randomized trial using low-dose amiodarone as an antiarrhythmic agent, could demonstrate a 60% reduction in sudden death rate and a 74% reduction in arrhythmic events incidence during the first year after myocardial infarction. Therefore, in patients with repetitive ventricular ectopic activity after myocardial infarction and adequate left ventricular function, a therapeutic attempt with beta-blockers without intrinsic sympathomimetic activity seems advisable. Beside beta-adrenergic blockade, low-dose amiodarone is an alternative, especially in patients with impaired left ventricular function or other contraindications for beta-blockers.

Anti-Arrhythmia Agents↗

PubMed1990

[Transesophageal echocardiography].

Transesophageal echocardiography is a new, semi-invasive technique for the examination of the heart and the aorta. Within 10-15 minutes it is possible to obtain good pictures of the anatomy and function of the heart. Diagnostic indications are native and prosthetic valvular heart disease; the method is particularly suitable for visualization of endocarditic vegetations, evaluation of embolic events or congenital heart disease and assessment of aortic dissection. In the intensive care unit transesophageal echocardiography is a new window to the heart, yielding instantaneous information on cardiac status. For the anesthetist it is the first method to provide perioperative beat to beat analysis of ventricular function.

Aortic Dissection↗

PubMed1990

[Clinical presentation and diagnosis of coronary heart disease].

Coronary artery disease may present as silent ischemia, chronic typical angina pectoris, unstable angina, Prinzmetal angina, acute myocardial infarction, and sudden cardiac death. These manifestations can usually be differentiated by the clinical history. Each of them has its own pathophysiology and, accordingly, therapy and prognosis are different. Myocardial ischemia is common to all of the manifestations and this can be assessed by history taking, ECG stress-testing, ambulatory monitoring, myocardial perfusion scanning, or radionuclide angiography (RNA). The diagnostic accuracy of these diagnostic procedures varies from 70% (history) to 81% (RNA).

Coronary Disease↗

PubMed1990

Patients at risk for cardiac death late after aortic valve replacement.

A total of 100 patients aged 24 to 78 years were screened prospectively a mean of 71 months after aortic valve replacement for the presence of left ventricular hypertrophy (LVH) on the ECG (Estes scores greater than or equal to 5.0) and for repetitive ventricular premature beats VPBs greater than or equal to 2 couplets/24 hr) during 24-hour Holter monitoring. During the subsequent 41-month follow-up (range 10 to 50 months), the yearly cardiac mortality rate was 1.3% in patients with LVH, 2.9% in patients with VPBs, and 8.0% in patients with LVH plus VPBs but only 0.6% when none of these factors was present (p less than 0.05 chi 2 test). The patient groups did not differ with regard to age, time elapsed since operation, underlying valve lesion, and coronary artery disease. Both LVH and VPBs occurred more frequently in patients with left ventricular dysfunction. We conclude that after aortic valve replacement cardiac mortality is markedly increased in patients with LVH and repetitive VPBs, since they are noninvasive markers of left ventricular dysfunction.

Adult↗

PubMed1990

Prevention of aortocoronary vein bypass graft occlusion: which antithrombotic treatment and for how long?

The effects of 50 mg aspirin combined with 400 mg dipyridamole were compared with those of standard anticoagulant therapy, in the prevention of aortocoronary vein bypass graft occlusion. Early graft occlusion in 249 patients, with 749 distal vein graft anastomoses, were angiographically assessed 11.5 +/- 2 days after surgery and were almost equal in both treatment groups. In half of the patients in each group, active treatment was replaced by placebo after 3 months. Repeat angiography after 1 year (360 +/- 24 days) showed that more new late graft occlusions occurred in patients with only 3 months active medication (either regimen). The incidence of major complications was significantly higher in patients treated with anticoagulants, with minor side-effects more common in the antiplatelet group. Thus, this antiplatelet drug regimen was as effective as standard anticoagulant therapy in the prevention of early and late bypass graft occlusion, but carried a significantly lower risk of severe complications. In addition, as replacement of active treatment by placebo after 3 months resulted in significantly more graft occlusions, antithrombotic treatment should be continued for at least one year after coronary artery bypass graft surgery.

Adult↗

PubMed1990

Long-term follow-up of patients with silent ischemia during exercise radionuclide angiography.

A retrospective 5 year follow-up study was performed in 140 patients with unequivocal ischemia during exercise radionuclide angiography (greater than or equal to 10% decrease in left ventricular ejection fraction or greater than or equal to 5% decrease in ejection fraction together with a distinct regional wall motion abnormality). In 84 patients (60%), ischemia during radionuclide angiography was silent (silent ischemia group), whereas 56 patients experienced angina during the test (symptomatic group). Work load and antianginal medication were similar in both groups. Critical cardiac events (unstable angina, myocardial infarction, cardiac death) occurred in 27% of patients in the silent ischemia group and 16% of those in the symptomatic group (p = NS); however, myocardial infarction or death was more frequent in patients with silent ischemia (22% versus 9%; p less than 0.05). If there was additional exercise-induced ST segment depression, the rate of critical events was further increased (p less than 0.05). The difference in critical cardiac events seemed to be influenced by the higher incidence of revascularization procedures in symptomatic patients, whereas medical therapy had no similar effect. Thus, these findings suggest that patients with documented severe ischemia should undergo left heart catheterization and revascularization irrespective of symptoms to improve their prognosis.

Adult↗