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Biomedical subjects

H De Geest

Publications and source records attributed to H De Geest.

At least 163 records · Page 9Linked to original sources
PubMed1982

Relationship between apexcardiogram, left ventricular pressure and wall stress.

Simultaneous measurement of left ventricular dimension and wall thickness by M-mode echocardiography, of left ventricular pressure by a tip-transducer manometer, and of the calibrated apexcardiogram with a pixie beam transducer, were made during acute experiments on anaesthetized dogs. Instantaneous values for chamber dimensions and wall thickness were obtained throughout the heart cycle by digitizing the echo-mechanocardiograms. From these data myocardial stresses, derived from a thick shell theory (meridional and circumferential components) and from Laplace's law, were computed. Laplace stress if shown to be an adequate expression for average wall stress. Its value was correlated with the calibrated apexcardiogram. The present investigation suggests that to a certain extent, the apexcardiogram not only reflects pressure changes but also dimensional changes of the left ventricle.

Animals↗
PubMed1982

The underlying heart rhythm in patients with an artificial cardiac pacemaker.

One-hundred forty-two patients with atrioventricular block (AVB) and 61 patients with sick sinus syndrome (SSS) were followed for an average of 50 months after permanent pacemaker insertion. Their underlying heart rhythms (UHR) were evaluated repeatedly by chest wall stimulation (CWS). A deficient UHR was defined as ventricular asystole lasting 4 seconds or longer. The underlying conduction disturbance increased in 14% of AVB patients, decreased in 14%, and remained constant in 68%. The occurrence of Adams-Stokes attacks before pacemaker implantation was associated with a higher incidence of deficient UHR both in AVB and SSS; a deficient UHR was seen more frequently in AVB than in SSS. Among AVB patients (1) atrial fibrillation, flutter or tachycardia and (2) sinus rhythm with incomplete AVB, especially Mobitz 1, when present before pacemaker implantation, were associated with a significantly lower incidence of deficient UHR during subsequent pacing in comparison with other AVB patients. CWS is a non-invasive method which allows the evaluation of UHR and which can contribute to the early recognition of pacemaker-dependent patients.

Aged↗
PubMed1981

Ultrastructural correlates of left ventricular contraction abnormalities in patients with chronic ischemic heart disease: determinants of reversible segmental asynergy postrevascularization surgery.

The relationships between structural alterations and left ventricular (LV) contraction abnormalities were studied in patients with coronary artery disease (CAD). Transmural biopsies of the LV anterior free wall were taken during aortocoronary bypass surgery (CABG) in 62 patients. When preoperative anterior wall motion (AWM) was reduced, significant myocardial cell degeneration was found in patients with as well as without previous anterior infarction (MI). The amount of myocardial fibrosis was increased only in patients with ECG evidence of previous anterior MI (p less than 0.001). In a second series of 139 CAD patients, cineventriculograms performed before and 8 months after CABG were examined. In patients with patent grafts to the LV anterior wall not previously infarcted, reduced AWM became normal. In patients with previous anterior MI the outcome of AWM was unpredictable (usually unimproved). Thus the histologic correlate of reduced AWM in segments not previously infarcted was progressive loss of contractile material in otherwise viable myocardial cells. Some reversibility was suggested by restoration of resting function after CABG. Unpredictable results in segments associated with pathologic Q waves appear related to the fibrous component of these previously infarcted areas.

Adult↗
PubMed1981

Coronary arterial lesions in young men who survived a first myocardial infarction: clinical and electrocardiographic predictors of multivessel disease.

An analysis was made of clinical and electrocardiographic prognostic determinants of multiple vessel disease in 100 men, aged under 45 years, who survived a myocardial infarction. All patients underwent selective coronary arteriography within 1 year after sustaining a myocardial infarction. Multivessel disease was present in 64 patients; 33 patients had single vessel disease and 3 had either normal coronary arteries or minimal lesions. Exercise stress testing, electrocardiographic location of the infarction, total serum cholesterol and clinical features including body build, arterial blood pressure, smoking habits, family history of coronary artery disease and the presence of angina pectoris either before or after the acute event proved to be poor predictors of multiple vessel disease. Only 74 percent of the patients were correctly classified by a discriminant function analysis. Thus, for prognostic reasons, coronary arteriography seems warranted in young patients after acute myocardial infarction, even in the absence of residual angina or multiple risk factors.

Adult↗
PubMed1979

Comparability and reproducibility of apex cardiogram recorded with six different transducer systems.

A comparison was made in 7 dogs of the results obtained by 6 different apex cardiographic transducers applied before, during, and after controlled infusion of angiotensin and isoprenaline. The electrocardiogram, internal phonocardiogram, aortic and left ventricular pressure using a Telco micromanometer, and apex cardiogram were recorded simultaneously on magnetic tape and paper. Digital computer techniques were used to derive various measurements. The comparison of the 6 transducer systems was made expecially with respect to measurements derived from the normalised derivative, calculated using total as well as developed pressure or displacement. Measurements derived from left ventricular pressure were very reproducible. Differences in results of 'contractility' indices varied between 0.5 and 1.9 per cent. Indices from the apex cardiogram using 6 different transducer systems showed variations up to 20 per cent, with mean values varying between 3.2 and 8.1 per cent. There was a systematic deviation for one transducer system, which was responsible for a significant part of the observed variability. It may be concluded that in order to assure maximal reproducibility, technical characteristics of the apex cardiograph transducer should be taken into account and an optimal recording technique should be used.

Angiotensins↗
PubMed1978

A new test for pacemaker leads: capacitance measurement.

A device has been developed which permits in man the measurement of the capacitance of a chronically implanted pacemaker lead at the moment of battery replacement. A large increase in capacitance suggests important body fluid penetration into the lead. This can be due to an insulation defect (caused by a suture or a guide wire during implantation) or to a degeneration of the insulation material or to the lead-design. This fluid penetration should be avoided since it can be responsible for some electro-chemical reactions. Calculated values for the capacitance of a system consisting of an inner and an outer conductor, with two media in between, agree rather well with measured values. It is suggested that the measurement of the capacitance of a pacemaker lead is an additional tool for the evaluation of chronically implanted pacemaker leads. This method can also be of interest for the quality control of pacemaker leads.

Electric Conductivity↗
PubMed1978

Value of apexcardiography for the timing of left ventricular events in man.

The time relationship between left apexcardiogram and left ventricular pressure was studied in 56 patients with heart disease. The apexcardiogram was recorded by means of a pressure transducer in 20 patients (group I). In 36 patients a displacement transducer was used (group II). The beginnings of the systolic upstroke of left ventricular pressure and left apexcardiogram were nearly simultaneous in both groups. The protodiastolic nadir of the apex tracing, however, preceeded the corresponding point on the pressure tracings by 23.8 msec in group I and 7.8 msec in group II (mean values). The peak of the first derivative of the apexcardiogram in group II preceeded the peak of the first derivative of the intraventricular pressure by a mean of 13.4 msec. In group I the time difference was small and statistically insignificant. It is concluded that apexcardiography allows an accurate determination of the onset and time course of ventricular contraction but is less precise for the determination of the protodiastolic nadir.

Blood Pressure↗
PubMed1977

Subacute bacterial endocarditis due to Actinobacillus actinomycetemcomitans. Report of a case with a review of the literature.

A case of subacute bacterial endocarditis due to Actinobacillus actinomycetemcomitans is reported. The patient was successfully treated first by a combination of gentamicin and ampicillin and then, because of severe allergic reactions, ampicillin was replaced by co-trimoxazole; symptoms did not recur and blood cultures remained sterile. A synoptic table is presented of 19 reported cases of infection caused by A. actinomycetemcomitans not connected with actinomycosis, with particular regard to their clinical features, treatment, and outcome.

Actinobacillus↗
PubMed1977

Initial experience with coronary artery bypass graft surgery. A follow-up study.

The preoperative, postoperative and late follow-up data of an initial series of two hundred patients with coronary artery disease, who underwent direct coronary artery surgery, were analyzed. With increasing experience operative mortality, postoperative complications, graft closure and perioperative myocardial infarction showed a definite decrease. Patency rate was definitely related to symptomatic relief, return to work, postoperative exercise tolerance, and the absence of perioperative myocardial infarction.

Angina Pectoris↗