Search PubMed⌕ Search

Biomedical subjects

W G Daniel

Publications and source records attributed to W G Daniel.

At least 145 records · Page 8Linked to original sources
PubMed1992

[Acoustic quantification--a new online procedure for automatic recording of left ventricular areas and area changes in the echocardiogram].

Initial experiences were obtained with a new technique for automatic quantification of left ventricular areas and area changes in two-dimensional (2D) echocardiograms (acoustic quantification, AQ). AQ is based on integrated back-scatter-analysis in real-time. Practicality and reliability of AQ were studied in 50 non-selected patients. AQ measurements of left-ventricular (LV) cavities were compared with off-line measurements which were obtained by analysis of videotaped images. Thirty-two (64%) and 39 (78%) patients could be studied by AQ from parasternal and apical views, respectively. LV areas measured from parasternal views or apical views showed a good correlation with corresponding values obtained by off-line analysis (r = 0.78 to 0.91). In addition, LV fractional area changes measured by AQ showed an excellent correlation with off-line measurements (parasternal: r = 0.86; apical: r = 0.84). During infusion of dobutamine (n = 3; 5, 10, 20 micrograms/kg/min, 10 min each dose), reduction of LV cavity areas could be continuously monitored and quantified by AQ for each cardiac cycle. In five of six patients who underwent transesophageal echocardiography, AQ could easily detect LV contours in the transgastric short axis view. Although AQ is not practicable in all patients, this new technique appears to be a promising and reliable approach for real-time, automatic boundary detection in 2D echocardiograms.

Adolescent↗
PubMed1991

Percutaneous transluminal angioplasty of aortocoronary venous bypass grafts and effect of the caliber of the grafted coronary artery on graft stenosis.

The influence of morphologic parameters on the recurrence of stenosis after percutaneous transluminal coronary angioplasty of 49 stenoses in aortocoronary venous bypass grafts of 41 patients was investigated. Vessel dimensions were measured quantitatively. Angioplasty was successful in 46 stenoses (94%) of 38 patients (93%). In 35 patients (92% of successfully treated patients) with 42 stenoses, control angiography was performed after a mean interval of 189 +/- 186 days. In 9 patients (26%), 9 stenoses (21%) had recurred. The diameter of the grafted coronary artery distal to the anastomosis was significantly smaller in grafted arteries with than without recurrent stenoses (1.92 +/- 0.52 vs 2.45 +/- 0.50 mm; p less than 0.01). Recurrence also correlated with the ratio between graft diameter and coronary artery diameter greater than 1.35 (p less than 0.02) and with the stenosis length greater than 10 mm before angioplasty (p less than 0.01). Graft age, graft diameter and stenosis location in the graft had no significant influence on recurrence. Thus, the diameter of the grafted coronary artery and the length of the critical stenosis are parameters for recurrence after angioplasty of graft stenoses and should be considered in the selection of patients for this intervention.

Aged↗
PubMed1991

Improvement in the diagnosis of abscesses associated with endocarditis by transesophageal echocardiography.

BACKGROUND: Echocardiography is recognized as the method of choice for the noninvasive detection of valvular vegetations in patients with infective endocarditis, with transesophageal echocardiography being more accurate than transthoracic echocardiography. The diagnosis of associated abscesses by transthoracic echocardiography is difficult or even impossible in many cases, however, and it is not known whether transesophageal echocardiography is any better. METHODS: To determine the value of transesophageal echocardiography in the detection of abscesses associated with endocarditis, we studied prospectively by two-dimensional transthoracic and transesophageal echocardiography 118 consecutive patients with infective endocarditis of 137 native or prosthetic valves that was documented during surgery or at autopsy. RESULTS: During surgery or at autopsy, 44 patients (37.3 percent) had a total of 46 definite regions of abscess. Abscesses were more frequent in aortic-valve endocarditis than in infections of other valves, and the infecting organism was more often staphylococcus (52.3 percent of cases) in patients with abscesses than in those without abscesses (16.2 percent). The hospital mortality rate was 22.7 percent in patients with abscesses, as compared with 13.5 percent in patients without abscesses. Whereas transthoracic echocardiography identified only 13 of the 46 areas of abscess, the transesophageal approach allowed the detection of 40 regions (P less than 0.001). Sensitivity and specificity for the detection of abscesses associated with endocarditis were 28.3 and 98.6 percent, respectively, for transthoracic echocardiography and 87.0 and 94.6 percent for transesophageal echocardiography; positive and negative predictive values were 92.9 and 68.9 percent, respectively, for the transthoracic approach and 90.9 and 92.1 percent for the transesophageal approach. Variation between observers was 3.4 percent for transthoracic and 4.2 percent for transesophageal echocardiography. CONCLUSIONS: The data indicate that transesophageal echocardiography leads to a significant improvement in the diagnosis of abscesses associated with endocarditis. The technique facilitates the identification of patients with endocarditis who have an increased risk of death and permits earlier treatment.

Abscess↗
PubMed1991

Anginal symptoms without ischemic electrocardiographic changes during ambulatory monitoring in men with coronary artery disease.

Episodes of angina pectoris without electrocardiographic (ECG) signs of myocardial ischemia during 24-hour ambulatory monitoring were studied in 128 patients with a history of stable angina, angiographically proven coronary artery disease and positive exercise test results. In all, 341 episodes of ischemic ECG changes (ST-segment depression greater than 1 mm for greater than 1 minute) and 190 episodes of angina pectoris were observed: 86 episodes consisted of both ECG changes and angina pectoris, 255 episodes consisted only of ECG changes, and 104 episodes only of angina pectoris. Duration and magnitude of ST-segment deviation and heart rate at the onset of ischemia were similar in the 86 symptomatic and the 255 asymptomatic episodes with ECG changes. The 104 episodes of angina pectoris without ECG changes were detected in 44 patients (34%) (group A); 29 of them had only episodes with angina pectoris and 15 patients had both--episodes of angina pectoris with and without ECG changes. In 84 patients (66%) (group B) angina pectoris without ECG changes was not observed; all episodes were accompanied by ischemic ECG changes in these patients. No differences in the angiographic extent of coronary artery disease and in exercise test data were seen in both groups A and B; however, maximal ST-segment depression during exercise testing was significantly greater in group B than in group A patients (2.4 +/- 0.8 mm vs 1.9 +/- 0.9 mm; p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Diagnosis of noninfective cardiac mass lesions by two-dimensional echocardiography. Comparison of the transthoracic and transesophageal approaches.

This study was conducted in 46 patients with cardiac thrombi, 15 patients with atrial myxomas, and 32 patients with other cardiac or paracardiac tumors. Diagnoses were subsequently proven by surgery, autopsy, computed tomography, magnetic resonance imaging, or angiography in all patients. All patients underwent precordial and transesophageal two-dimensional echocardiography to assess the various mass detection rates. Atrial myxomas and predominantly left-sided cardiac tumors were identified by both echocardiographic techniques with comparable detection rates. Left ventricular apical thrombi were detected more frequently by precordial echocardiography. In contrast, transesophageal echocardiography was superior in visualizing left atrial appendage thrombi, small and flat thrombi in the left atrial cavity, thrombi and tumors in the superior vena cava, and masses attached to the right heart and the descending thoracic aorta. These data indicate that transesophageal echocardiography leads to a clinically relevant improvement of the diagnostic potential in patients in whom cardiac masses are suspected or have to be excluded in order to ensure the safety of clinical procedures.

Adult↗
PubMed1991

Safety of transesophageal echocardiography. A multicenter survey of 10,419 examinations.

BACKGROUND: During the past few years, transesophageal echocardiography (TEE) has been increasingly used in clinical cardiology; data concerning the practicability and safety of the technique, however, are rare. METHODS AND RESULTS: This report analyzes the experience of 15 European centers performing TEE studies for at least 1 year. At the time of this survey, 10,419 TEE examinations had been attempted or performed in these institutions. These TEE examinations were carried out by 54 physicians, 53.7% of whom had been trained in endoscopic techniques. Within the same time period, 160,431 precordial echocardiographic examinations were performed in the 15 institutions; the ratio between TEE and transthoracic studies averaged 9.03 +/- 6.4% (range of the 15 centers, 1.4-23.6%). Of the 10,419 patients, 9,240 (88.7%) were conscious inpatients or outpatients at the time of the TEE examination; the vast majority of the conscious patients did not receive intravenous sedation before TEE. In 201 cases (1.9%), insertion of the TEE probe was unsuccessfully attempted because of a lack of patient cooperation and/or operator experience (98.5%) or because of anatomical reasons (1.5%). In 90 of 10,218 TEE studies (0.88%) with successful probe insertion, the examination had to be interrupted because of the patient's intolerance of the echoscope (65 cases); because of pulmonary (eight cases), cardiac (eight cases), or bleeding complications (two cases); or for other reasons (seven cases). One of the bleeding complications resulted from a malignant lung tumor with esophageal infiltration and was fatal (mortality rate, 0.0098%). CONCLUSIONS: This multicenter survey documents that TEE studies are associated with an acceptable low risk when used by experienced operators under proper safety conditions.

Data Collection↗
PubMed1991

Increased thrombin levels during thrombolytic therapy in acute myocardial infarction. Relevance for the success of therapy.

BACKGROUND: It has been suggested that thrombolysis in a feedback reaction may generate pro-coagulant activities. METHODS AND RESULTS: Fifty-five patients were treated with urokinase-preactivated prourokinase (n = 35) or tissue-type plasminogen activator (n = 20) for acute myocardial infarction and underwent coronary angiography at 90 minutes and at 24-36 hours into thrombolysis, and fibrinogen (Ratnoff-Menzie), D-dimer (ELISA) and thrombin-antithrombin III complex levels (ELISA) were measured. Primary patency was achieved in 39 patients (70.9%), 13 of whom (33.3%) suffered early reocclusion. Nonsignificant decreases in fibrinogen levels were observed while D-dimer levels increased +3,008 +/- 4,047 micrograms/l (p less than 0.01), differences not being significant in respect to the thrombolytic agents or to the clinical course. In contrast, while thrombin-antithrombin III complex levels decreased -4.4 +/- 13.0 micrograms/l in patients with persistent patency, they increased +7.5 +/- 13.6 micrograms/l in case of nonsuccessful thrombolysis (p less than 0.02) and +11.9 +/- 23.8 micrograms/l in case of early reocclusion (p less than 0.001). For patients with thrombin-antithrombin III complex levels greater than 6 ng/l 120 minutes into thrombolysis, the unfavorable clinical course was predicted with 96.2% sensitivity and 93.1% specificity. CONCLUSION: Generation of thrombin, occurring during thrombolysis, is a major determinant for the success of therapy and thrombin-antithrombin III levels may serve as predictors for the short-term prognosis.

Antithrombin III↗
PubMed1991

Circadian variation of myocardial ischemia in patients with stable coronary artery disease.

The circadian variation of myocardial ischemia detected during 24-h ambulatory electrocardiographic monitoring (AEM) was analyzed in 123 patients with stable angina pectoris, positive exercise test, and angiographically proven coronary artery disease. A total of 437 ischemic episodes (ST-segment depression greater than or equal to 1 mm and duration greater than or equal to 1 min) were observed; 333 (76%) episodes remained asymptomatic, and only 104 (24%) episodes were accompanied by anginal pain. Ischemic episodes predominantly occurred during the morning hours, between 6 a.m. and noon, and another smaller peak was observed in the afternoon, between 4 and 5 p.m.; this diurnal pattern was influenced neither by the extent of coronary artery disease nor the degree of left ventricular dysfunction. The circadian variation was restricted to the 345 (78%) ischemic episodes preceded by increases in heart rate; the 92 (22%) episodes without prior heart rate changes occurred randomly throughout the day. The morning peak in ischemic episodes was not associated with less myocardial oxygen supply; in contrast, heart rate profile showed parallel increases during the morning and afternoon hours, indicating elevated myocardial demand during these periods. Ischemia-related ventricular arrhythmias were concentrated during the morning hours, but their overall prevalence was low--28 (6%) of 437 ischemic episodes. These findings may provide further insight into the pathomechanisms of acute clinical events in patients with coronary artery disease, since the circadian variation of myocardial ischemia is very similar to that observed for the onset of myocardial infarction and sudden cardiac death.

Adult↗
PubMed1991

[Cardiological diagnosis in arterial embolism].

Potential cardiac sources of arterial embolism are in particular thrombi within the left atrium or ventricle, or attached to a prosthetic valve, intracardiac tumors, and vegetations due to endocarditis. Patent foramen ovale and atrial septal defect may lead to paradoxical embolism, and spontaneous echo contrast within the heart has to be considered as a parameter of increased thromboembolic risk. In rare cases, atrial septal aneurysm, mitral valve prolapse or annulus calcification and calcified aortic stenosis has to be taken into consideration. Current method of choice for diagnosis of these abnormalities is echocardiography. When the transthoracic approach fails, transesophageal echocardiography (TEE) leads to a definite diagnosis in most cases. Precordial echocardiography allows the detection of left ventricular thrombi with a sensitivity ranging between 72 and 95%, and monoplane TEE does usually not increase these numbers. In contrast, thrombi within the left atrium and particularly in the left atrial appendage can be detected with a significantly higher detection rate when TEE is used. The same is true for spontaneous echo contrast in the left atrium, a phenomenon which is almost exclusively diagnosed by TEE, as well as for endocarditis associated vegetations that can be identified by TEE with a sensitivity higher than 90%. Patient foramen ovale is usually diagnosed by precordial contrast echocardiography combined with a Valsalva maneuver; color Doppler or contrast TEE allows to increase the detection rate. In the diagnosis of prosthetic valve attached thrombi and vegetations, TEE is clearly superior compared to the precordial examination, at least concerning prosthetic devices in mitral position. If echocardiography fails to identify a potential cardiac source of embolism, other techniques don't add significant information in most cases. Detection of a potential source of embolism, however, does not necessarily prove that the particular finding represents the true etiology of an embolic event; results of all clinical and technical examinations have to be evaluated in a critical synopsis. In addition, proper therapeutic consequences in quite a number of abnormalities considered as potential cardiac sources of embolism are not yet defined.

Echocardiography↗
PubMed1991

[Percutaneous, transluminal angioplasty of aortocoronary venous bypass grafts--acute success, angiography and clinical follow-up].

In 41 consecutive patients with 49 stenoses of aorto-coronary venous bypass (ACVB) grafts percutaneous transluminal angioplasty (PTA) was attempted. PTA was successful, i.e., the percent area stenosis was reduced by greater than 20% to less than 70% (quantitative measurement with a precision magnifying lens from two orthogonal angiographic views) in 46 stenoses (94%) of 38 patients (93%). In 35 patients (92%) with 42 stenoses control coronary angiography was performed after a mean interval of 189 +/- 186 days. Recurrence, defined as an increase of percent area stenosis to greater than or equal to 70%, was found in nine stenoses (21%) of nine patients (26%). Recurrence correlated with a stenosis length greater than 10 mm before PTA (5/8 vs 4/32 stenoses: p less than 0.01). In recurrent stenoses, the average diameter of the grafted native coronary artery was significantly smaller than in recurrence-free stenoses (1.92 +/- 0.52 mm vs 2.45 +/- 0.50 mm; p less than 0.01). Clinical data were collected from all 38 patients with successful PTA after an average of 30 +/- 17 months following PTA. In this interval, 11 patients had undergone re-angioplasty and eight patients were re-operated; in addition, there were three cardiac deaths. In the 27 surviving patients without re-operation (71%), angina pectoris had improved from a mean of 3.0 +/- 0.7 before PTA to 1.8 +/- 1.0 (CCS-classification) (p less than 0.001). In 19 of the 27 patients (70%) the exercise stress test was negative, in contrast to only three patients (11%) before PTA. Thus, in the majority of patients PTA of ACVB-graft stenoses improves quality of life.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1990

Circadian distribution of the characteristics of ischemic episodes in patients with stable coronary artery disease.

To determine the circadian distribution of episodes of myocardial ischemia, studies were performed in 111 patients with chronic stable angina pectoris, positive exercise test results and angiographically proven coronary artery disease. During 24 hours of ambulatory electrocardiographic monitoring, 101 symptomatic and 298 asymptomatic ischemic episodes (ST-segment depression greater than 1 mm, duration greater than 1 minute) were observed. The number of ischemic episodes and the cumulative duration of ischemia showed a circadian variation with the highest values between 8 and 10 A.M. and between 4 and 5 P.M. associated with a similar circadian variation of heart rate. Mean duration of ischemic episodes, maximal amplitude of ST-segment depression during ischemic episodes and increase in heart rate before the onset of ischemic episodes showed no significant circadian variation. Heart rate at the onset of ischemic episodes and maximal heart rate during ischemic episodes were lower between midnight and A.M. than during other times of the day. The morning and afternoon increase in ischemic activity is not paralleled by changes reflecting a decrease in myocardial oxygen supply during these periods (heart rate at onset of ischemia, heart rate increase before onset of ischemia), but is paralleled by a similar circadian variation of heart rate. The circadian variation in ischemic activity is predominantly based on a comparable variation in myocardial oxygen requirements.

Circadian Rhythm↗
PubMed1990

Role of thrombolysis and thrombin in patients with acute coronary occlusion during percutaneous transluminal coronary angioplasty.

In a series of 447 patients with single vessel angioplasty, 27 (6.0%) had acute thrombotic occlusion early after the procedure. They were treated with combined intracoronary (20 mg)/intravenous (50 mg) thrombolysis with recombinant tissue-type plasminogen activator (rt-PA) and repeat mild balloon inflations. Reopening of the vessel was achieved in 22 patients (81.5%). Follow-up coronary angiography 24 to 36 h later revealed reocclusion in 12 patients (54.5%). Thrombin levels measured as thrombin-antithrombin-III complex in patients with successful thrombolysis and persistent patency decreased from 8.5 +/- 11.4 micrograms/liter at baseline to 3.5 +/- 1.4 micrograms/liter 120 min after the start of thrombolysis; these levels increased from 9.4 +/- 15.0 micrograms/liter at baseline to 15.7 +/- 13.5 micrograms/liter 120 min after the start of thrombolysis in the patients with unsuccessful thrombolysis or early reocclusion (p less than 0.05). When a borderline value for thrombin-antithrombin-III complex level of 6 micrograms/liter was selected to separate the two groups of patients, patients with an unfavorable clinical course were identified 120 min after the start of thrombolysis by levels greater than 6 micrograms/liter (sensitivity 100%, specificity 92.8%). Thus, after abrupt thrombotic vessel closure during coronary angioplasty, the short-term results of thrombolysis seem to be governed by the release of thrombin. In two thirds of patients, however, the thrombin release cannot be suppressed by concomitant aspirin and heparin therapy. Even after successful reopening of the vessel these patients should therefore undergo immediate aortocoronary bypass grafting.

Angioplasty, Balloon, Coronary↗
PubMed1990

Incidence of ventricular arrhythmias during transient myocardial ischemia in patients with stable coronary artery disease.

To determine the incidence of ventricular arrhythmias related to episodes of transient myocardial ischemia during ambulatory electrocardiographic (ECG) monitoring, 97 patients with stable angina pectoris, angiographically proved coronary artery disease and an abnormal exercise test were studied. A total of 573 episodes with ST segment depression were documented: in 118 episodes (21%) the patients were symptomatic and in 455 (79%) they remained asymptomatic. Ventricular arrhythmias (greater than 5 premature ventricular beats/min, bigeminy, couplets or salvos of premature ventricular beats) occurred during 27 (5%) ischemic episodes in a subset of 10 patients (10%) (group A). The other 87 patients (90%) (group B) showed exclusively ischemic episodes without ventricular arrhythmias. Comparison of patients in group A and group B showed no differences in hemodynamic, angiographic, exercise testing and ambulatory ECG monitoring data. Ischemic episodes with and without ventricular arrhythmias showed a similar duration and amplitude of ST segment depression and a comparable heart rate at the onset of ischemia. Both types of ischemic episodes, with and without arrhythmias, occurred predominantly during the morning hours between 6:00 AM and noon, and both types remained asymptomatic to within similar percentages. The data demonstrate that ventricular arrhythmias are related to transient myocardial ischemia in only a few patients with stable angina pectoris; these arrhythmias are related neither to the degree of ischemia during ambulatory ECG monitoring nor to the occurrence of anginal symptoms.

Adult↗
PubMed1990

Renal artery embolism: thrombolysis with recombinant tissue-type plasminogen activator.

The case of a patient with acute occlusion of the right renal artery due to an embolus is described. Using transoesophageal echocardiography, the left atrial appendage could be identified as the source of embolism. Twenty hours after the onset of symptoms, the embolus could be successfully dissolved with an intra-arterial low-dose infusion of recombinant tissue-type plasminogen activator (10 mg loading dose, 20 mg continuous infusion within 12 h).

Aged↗