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Biomedical subjects

W G Daniel

Publications and source records attributed to W G Daniel.

At least 181 records · Page 10Linked to original sources
PubMed1987

[ST segment analysis in 24-hour long-term ECG in patients with stable angina pectoris and angiographically detected coronary sclerosis].

ST-segment analysis on 24-hour Holter ECG was performed in 64 patients with angiographically proven coronary artery disease, a positive exercise test and chronic stable angina. During 125 days of recording, 494 episodes of transient ST-segment depression were observed, at an average of 4.0 +/- 3.7 episodes (1-13 episodes, median: 3 episodes) per day. The duration of ST depression per episode was 13.2 +/- 14.4 min (1-90 min; median: 8 min). No episodes of ST-elevation were observed. Only 27 (5.5%) ischemic episodes occurred during the night, between midnight and 6:00 a.m., but they were frequently observed during the morning hours between 7:00 and 12:00 a.m. Nearly all episodes of ischemia were preceded by an increase in heart rate. However, heart rate at the onset of significant ST-segment depression was significantly lower during Holter monitoring than during exercise test (p less than 0.001); this indicates that factors additional to the increase in myocardial demand might be relevant for transient myocardial ischemia during daily life. 382 of the 494 episodes (77.3%) of ischemia were asymptomatic; heart rate at the onset of ST-segment depression was similar in symptomatic and asymptomatic episodes; however, in asymptomatic episodes, maximal heart rate was significantly lower (p less than 0.001) and the duration of the episodes significantly longer (p less than 0.001). The percentage of asymptomatic episodes was very high in patients with one-vessel disease, whereas the duration and amount of ST-segment depression, as well as heart rate, at the onset of ischemia, were not dependent on the extent of coronary artery disease.

Aged↗
PubMed1987

[M-mode echocardiography determination of the severity of aortic stenosis: is the assumption of constant wall stress a realistic approach?].

We reevaluated a previously described M-mode echocardiographic method for the assessment of the hemodynamic severity of an isolated or predominant, advanced aortic stenosis in 89 adult patients without significant associated coronary artery disease. Endsystolic left ventricular wall thickness and diameters were measured using the echocardiogram and left ventricular systolic pressure was calculated under the assumption of a constant left ventricular wall stress (235 mm Hg); the results were compared with the pressure values measured during catheterization. The correlation between the echocardiographic and the invasively determined pressure values was poor and without any clinical relevance; r-values ranged between 0.14 and 0.46. Calculated left ventricular wall stress showed a large scatter with values between 126 mm Hg and 468 mm Hg. Our data indicate that in adults with aortic stenosis, M-mode echocardiographic determination of the hemodynamic severity is not possible, and the assumption of a constant left ventricular wall stress in these patients is misleading.

Adult↗
PubMed1986

[Mycotic intracranial aneurysm in infective endocarditis of the mitral valve].

A 20-year-old woman suffering from mitral valve endocarditis due to streptococcus faecalis infection after blunt trauma and splenectomy complained of severe headache 18 days later. Cerebral angiography showed a left posterior artery aneurysm. A craniotomy was performed and the aneurysm could be successfully removed. The postoperative neurological status showed a mild transient right hemiparesis. The patient underwent mitral valve replacement with a St. Jude-Medical prosthesis 14 days after brain surgery. The patient was in stable neurologic and hemodynamic conditions at the time of discharge 3 weeks after valve replacement.

Adult↗
PubMed1986

[Importance of transesophageal echocardiography in the diagnosis of cardiac and paracardiac space-occupying processes].

The diagnostic value of transoesophageal echocardiography in the detection of cardiac and extracardiac masses has not yet been properly established. We therefore studied 23 patients (7 males, 16 females, mean age 54.7 years) using transoesophageal echocardiography in addition to conventional transthoracic echocardiography. Nine patients had an atrial thrombus, 6 an atrial myxoma and 8 extracardiac masses. The studies were performed without complications. Transthoracic as well as transoesophageal echocardiographic detection of atrial thrombus or myxoma (n = 15) was successful in all patients except 1 with a thrombus in the left atrial appendix, which could only be visualized by transoesophageal echocardiography. In contrast, accurate diagnosis of extracardiac masses could be established only by transoesophageal echocardiography in 5 of 8 patients (62.5%). In all 23 patients the judgement of the mobility of the tumor, as well as its acoustic properties and wall adherence was markedly facilitated by transoesophageal echocardiography. Thus, this method is a useful diagnostic tool for detection of extracardiac masses, whereas in patients with atrial thrombus or myxoma it can give important additional information.

Adult↗
PubMed1986

[Echocardiography detection of reduced left ventricular diastolic posterior wall motion in patients with constrictive pericarditis--incidence and correlation with hemodynamics and clinical course].

In 24 patients with chronic constrictive pericarditis (CP) proven by right and left heart catheterization, the amplitude of diastolic left ventricular posterior wall motion was evaluated by M-mode echocardiography and compared with the results of 14 healthy volunteers. The amplitude was significantly less in CP patients than in normal controls (0.3 mm vs. 4.0 mm, p less than 0.001) and no CP patient showed a higher value than 2 mm whereas none of the normal subjects had an amplitude less than 3 mm. In 11 of 13 CP patients undergoing pericardectomy, an increase in amplitude was observed; in 6 of them the amplitude was within normal limits following surgery. No significant correlation between the degree of heart failure or the level of left ventricular end-diastolic pressure and the reduction of the amplitude could be found. In addition, the level of the amplitude did not allow a clear separation between patients who could be treated medically and those requiring pericardectomy. It can be concluded that the reduction of diastolic left ventricular posterior wall motion is a valuable echocardiographic parameter for the noninvasive diagnosis of CP.

Adult↗
PubMed1985

Impending paradoxical embolism from atrial thrombus: correct diagnosis by transesophageal echocardiography and prevention by surgery.

During recovery from a posterolateral myocardial infarction, a 56 year old patient developed signs of deep vein thrombophlebitis and subsequently of pulmonary embolism. After conventional echocardiography showed masses in both atria, transesophageal two-dimensional echocardiography clearly revealed an elongated mass overriding an atrial septal defect. Impending paradoxical embolism was confirmed at surgery.

Echocardiography↗
PubMed1985

Chronic aortic regurgitation: reassessment of the prognostic value of preoperative left ventricular end-systolic dimension and fractional shortening.

The prognostic significance of a preoperative echocardiographic left ventricular end-systolic dimension (ESD) greater than 55 mm and/or fractional shortening (FS) of 25% or less was evaluated retrospectively in 84 patients who had undergone aortic valve replacement for isolated chronic aortic regurgitation due to various causes. Postoperative survival, improvement in symptoms, and echocardiographic evidence of regression of left ventricular dilatation and hypertrophy were compared between patients with a preoperative ESD greater than 55 mm (category 1) and those with an ESD of 55 mm or less (category 2) and between patients with FS of 25% or less (category 3) and those with FS greater than 25% (category 4). Patients in categories 1 and 3 had a higher preoperative left ventricular end-diastolic dimension (EDD) and cross-sectional area than those in categories 2 and 4, respectively, but their preoperative functional impairment (NYHA class) was similar. There were 13 deaths, only two of which (one early, one late) could be attributed to left ventricular dysfunction. In both, FS was 25% or less and in one ESD was greater than 55 mm. There was a weak association without useful positive predictive value between the echocardiographic variables and postoperative death due to all causes. Among 42 patients with a preoperative ESD greater than 55 mm and/or FS of 25% or less, 33 (79%) were alive at a mean follow-up of 29.5 months. Symptoms improved in all categories of survivors, with the postoperative NYHA class being similar between categories 1 and 2 and between categories 3 and 4. Among 48 survivors with high-quality echocardiograms both before and after surgery, EDD fell in all groups but fell to a lesser extent in category 3 than in category 4. Postoperative cross-sectional area fell to the same level in all categories. Follow-up intervals were similar in all categories. We conclude that in patients undergoing aortic valve replacement for chronic aortic regurgitation, a preoperative ESD greater than 55 mm or an FS of 25% or less does not reliably predict early or late death, does not correlate with lack of improvement in symptoms, and does not preclude postoperative regression of left ventricular dilatation and hypertrophy. Thus these echocardiographic criteria alone cannot be used for the timing of surgical intervention in these patients.

Adolescent↗
PubMed1984

[Infectious endocarditis: clinical aspects and diagnosis].

In a discussion of infectious endocarditis (IE), the clinical picture, current most important diagnostic methods (especially echocardiography) and prognosis under conservative therapy and valve replacement are described in detail, in the light of experience at the Hanover Medical School in recent years. While the clinical picture is usually typical, at any rate in the early stages of the disease, antibiotic therapy (when started without blood cultures and exact characterization of the germs involved) or severe complications can change the symptoms to the extent that diagnosis becomes very difficult. Apart from blood cultures, echocardiography, is of prime importance in diagnosis, the latter allows demonstration of vegetations either by M-mode or two-dimensional echocardiography (conventional or esophageal) in some 80% of cases. A special situation is encountered in prosthetic valve endocarditis (PVE): although the incidence of early PVE (which follows hard on the heels of valve replacement) is decreasing, mortality is still high despite early reoperation. Late PVE (after a free interval of approximately 2 months to years) resembles IE of the native valves and often allows medical treatment, especially in the presence of biological valves. The prognosis in IE is still poor and depends mainly on early diagnosis, i.e. a very early start with antibiotic treatment, which must be based on a positive bacterial diagnosis.

Anti-Bacterial Agents↗
PubMed1984

Is renal involvement a prognostic parameter in patients with infective endocarditis?

Renal involvement (RI)--defined as proteinuria greater than 150 mg per 24 h with haematuria or impaired glomerular filtration rate--was studied in 80 patients with infective endocarditis (IE). Proteinuria was measured quantitatively and further differentiated by the SDS-polyacrylamide-gel electrophoresis. RI was found in 40 patients (50%) with proteinuria from 150 to 8000 mg per 24 h. SDS-PAGE revealed a tubular protein pattern in 17 patients, a glomerular pattern in 6 and a glomerulo-tubular pattern in 17. Mortality rate was significantly higher in patients with RI (40%) than in those without (7.5%), and was not related to the type of infected valve, infective organisms, method of treatment (surgical or medical) or embolic events. Following successful treatment of IE, 18 out of 23 patients showed complete normalization of renal function. Renal involvement in patients with IE may be of prognostic significance--indicating an impaired prognosis.

Adolescent↗
PubMed1983

Value and limitations of computed tomography in assessing aortocoronary bypass graft patency.

To determine the value of nondynamic computed tomography (CT) in assessing aortocoronary bypass graft patency, we studied 67 patients with 125 grafts by CT and by coronary angiography at close time intervals. CT scans were performed before and after one to three (average 1.98 +/- 0.65) 50-ml i.v. bolus injections of contrast material. Eighty-four of 92 grafts patent at angiography were also visualized by CT (sensitivity 91.3%); 29 of 33 grafts closed at angiography were considered to be occluded by CT (specificity 87.9%). Eleven of 13 grafts demonstrating one or more severe obstructions at angiography were considered to be patent by CT. Interobserver disagreement existed in four of 125 grafts (3.2%) and intraobserver variability was 1.6%. Although nondynamic CT allows a correct assessment of graft patency in many cases, it does not provide sufficient information on graft stenosis and function to replace angiography in patients who are symptomatic after surgery.

Adult↗
PubMed1978

Electrophysiologic effects of partial coronary flow reduction in the exposed canine heart. Effects of ischemia and ischemic-induced regional hypothermia on refractoriness and conduction delay.

In the open-chested dog, coronary flow reduction results in a decrese of regional myocardial temperature (T). We assessed the contribution of T decrease to changes in refractoriness and conduction delay attributed to ischemia. The independent effect of regional hypothermia on effective refractory period (ERP) was a linear function of the temperature (ERP = -b T +a) with a -r = 0.97 0.02 in 11 dogs. The effect on conduction time of a ventricular premature beat was a linear function of the dog T at both endocardium (-r = 0.95 +/- 0.02) and epicardium (-r = 0.96 +/- 0.01). A 75% reduction in coronary flow resulted in a mean T decrease of 1.0 +/- 0.3 degrees C. The T decrease was sufficient to mask the effects of ischemia on shortening of the ERP. Furthermore, the conduction delay of ventricular premature beats during 75% coronary flow reduction could be accounted for by the decrease in T alone in five of seven dogs. We conclude that changes in refractoriness and conduction during acute coronary flow reduction in the open-chested dog are due to the composite effects of ischemia and the decrease in regional temperature. The open-chested model may have important limitations in understanding the electrophysiologic effects of acute coronary insufficiency. However, it may have important applications in defining the electrophysiologic environment at the time of coronary artery surgery.

Animals↗