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Biomedical subjects

H De Geest

Publications and source records attributed to H De Geest.

At least 181 records · Page 10Linked to original sources
PubMed1976

Normalized first derivative ofthe left apex cardiogram in assessment of left ventricular function.

The relation between the left displacement apex cardiogram and the left ventricular pressure during isovolumic contraction was studied in 30 patients with cardiac disease. Using the instantaneous relation between the first time derivative and the magnitude of both the left apex cardiogram and the left ventricular pressure, normalized derivatives were obtained. These noramized velocities were correlated with each other and with several indexes of left ventricular function. The normalized derivatives of the left apex cardiogram (dD/dt/D) and the left ventricular pressure (dP/dt/P) were similar in magnitude, standard deviation and variation coefficient. No such similarity was present when the first time derivatives of each tracing (dD/dt and dP/dt) were compared. A highly significant relation was found between normalized displacement velocity and normalized pressure velocity using both total (r = 0.76, P less than 0.001) and developed (r = 0.75, P less than 0.001) displacement and pressure. Significant correlations with several other indexes of left ventricular function (end-diastolic pressure, peak dP/dt, maximal velocity of the contractile elements at zero load[Vmax]) were also observed. It is concluded that the index dD/dt/D of the left apex cardiogram is an important noninvasive tool for assessing left ventricular function in man.

Adult↗
PubMed1976

Familial centronuclear myopathy associated with 'cardiomyopathy'.

Two cases of familial centronuclear myopathy are described. Both presented features of 'cardiomyopathy and one had signs of slight congenital aortic stenosis. The 'cardiomyopathy' was fatal in one case. The clinical histological, and necropsy findings are presented and discussed.

Adolescent↗
PubMed1976

Results of follow-up study in cardiac pacing at St. Raphael University Hosital in Leuven.

After this follow-up period some data seem important for the future: 1. Sudden failure never occurred for ventricular asynchronous units. Moreover battery survival time of fixed rate units is longer than that of ventricular-inhibited units. On the other hand, the use of fixed rate pacers avoids a number of demand function-related electrode difficulties. We must be aware of false signals generated by malfunctioning electrodes. 2. The reliability of a pacemaker clinic improves by replacing ventricular-inhibited units after 34 months. 3. Despite the additional work and cost we feel that photoanalysis is indispensable in today's pacemaker clinic.

Electrodes, Implanted↗
PubMed1976

Anomalous coronary arterial pattern.

The clinical history of an adult patient with anginal-like pain is described. A coronary angiography revealed the existence of a hypoplastic left coronary artery, a right coronary artery which passed around the posterior surface of the heart and continued into the anterior surface of the heart to give off an anterior descending artery and the presence of a "conus" artery. The embryonic genesis of hypoplastic coronary artery and of a similar aberration, single coronary artery, are discussed.

Angiography↗
PubMed1975

Additive effects of acetylcholine released by vagal nerve stimulation on atrial rate.

In reserpinized dogs, the decrease in atrial rate (AR) as a function of the frequency of stimulation (supramaximal strength) of a single vagal nerve can be described satisfactorily by a rectangular hyperbola (RH). If the RH of one vagal nerve has been determined and if one point of the RH of the other vagal nerve is known, then the latter RH can be determined. Both RHs being known and assuming that the acetylcholine released by the right and left vagal nerves is additive, the slowing of AR by simultaneous stimulation of both nerves can be predicted. A minor systematic deviation from the predicted AR during simultaneous stimulation is usually found, which could be accounted for by a time dependent decrease of the effect of vagal nerve stimulation. The results are qualitatively similar during norepinephrine infusion. We propose that, although the vagal innervation may vary from pacemaker cell to pacemaker cell, the ratio of the activities of the two vagal nerves is constant throughout the sinoatrial node.

Acetylcholine↗
PubMed1975

A comparison of systolic time intervals derived from the central aortic pressure and from the external carotid pulse tracing.

In 26 patients a direct comparison was made of systolic time intervals derived from the right and left external carotid pulse tracing and from the central aortic pressure, simultaneously recorded by means of a catheter-tip micromanometer. In addition, the delay time (required for pulse wave transmission to the neck) of the upstroke (DUEC) and incisura (DIEC) of the external carotid pulse tracing was studied. The influence of changes in heart rate on these intervals was evaluated by right atrial pacing. At resting frequencies DUEC exceeded DIEC by 4 to 4.5 msec (P less than 0.005). Increasing heart rate did not influence DUEC but prolonged DIEC. Differences between DUEC and DIEC were associated with a decrease and reversal with increasing heart rate (tau = 0.52, on the right carotid pulse; tau = 0.65, on the left pulse). Internally and externally measured left ventricular ejection time and pre-jection period were strongly correleated. Significant differences in absolute values were also observed. Whether these differences were positive or negative was dependent on heart rate. At rest external left ventricular ejection time was 4 to 4.5 msec (P less than 0.005) shorter, external pre-ejection period 5.5 to 6 msec (P less than 0.005) longer than corresponding intervals measured internally. At heart rates above plus or minus 100 beats/min the relationships were reversed. No significant differences could be demonstrated between these intervals measured on the right and left external carotid pulse.

Adult↗
PubMed1975

A direct comparison between internally and externally measured left ventricular systolic time intervals.

In 38 cardiac patients a direct comparison was made of systolic time intervals derived from the external carotid pulse tracing and from the central aortic pressure curve, simultaneously recorded by means of a catheter-tip micromanometer. In addition the transmission time of the upstroke and the incisura of the central pulse wave to the carotid artery was studied. In spite of close linear correlations, significant differences in absolute values were observed between internally and externally measured systolic time intervals. The transmission times of upstroke and incisura of the pulse wave also differed significantly. Both findings were directly related and dependent upon the heart rate.

Adult↗
PubMed1975

Left ventricular systolic time intervals during acute myocardial infarction.

Left ventricular systolic time intervals (LVSTI) were measured several times daily during 10 days in 47 patients with acute myocardial infarction without major complications. Left ventricular ejection time (LVET) and the interval between the beginning of depolarization and the aortic component of the second heart sound (Q-A2) decreased progressively during the first 72 hr. Shortening of Q--A2 and LVET was most marked in patients with heart failure and persisted till the end of the observation period. Q-upstroke (Q-U) prolonged progressively during the first 3 days, mainly in patients with heart failure. After 10 days, Q-U tended to return to normal except in decompensated patients. Definite diurnal variation in LVSTI were observed; LVET and Q--A2 were longest in the morning hours. Multiple regression analysis of LVSTI with a series of clinical variables revealed that R-R interval, age, sex, digitalis administration, day after infarction, hour of the day, peak of SGOT, and survival are significantly and independently correlated with the changes in LVSTI.

Acute Disease↗