B.-K. Jüngst

Effects of dobutamine on left ventricular performance in newborns as determined by systolic time intervals

To evaluate the effects of dobutamine on myocardial function in newborns, left ventricular systolic time intervals (STI) — normalized pre-ejection period (PEPI), normalized left ventricular ejection time (LVETI) and pre-ejection period to left ventricular ejection time ratio (PEP/LVET) — were assessed by echocardiography in 18 newborns treated with dobutamine for clinically diagnosed heart failure. Examinations were performed prior to and 30 min after starting dobutamine infusion (7.5 or 10 μg/kg per min). Patients were assigned to two groups according to their PEP/LVET prior to dobutamine administration: group I (n=9) with pre-treatment PEP/LVET ≤ 0.35 and group II (n=9) with pre-treatment PEP/LVET > 0.35. While there was no change of STI in group I, dobutamine infusion resulted in a significant decrease in PEPI (from 102±4.8 to 87.8±4.2; mean ± SEM;P<0.01) and of PEP/LVET (from 0.56±0.05 to 0.45±0.05; mean ±SEM;P<0.01) and in a significant increase of LVETI (from 237.6±5.6 to 253.3±5.2; mean ±SEM;P<0.01) in group II. Heart rate increased significantly in both groups. Left ventricular end-diastolic dimension, also assessed by echocardiography, did not change in the eight studies performed. An increase in mean arterial pressure was found in three out of five newborns of group II and in one out of four patients in group I. It is concluded that dobutamine can improve cardiac performance in newborns with impaired left venfricular function. This effect is probably due to an improvement in myocardial contractility.

Continuous monitoring of mixed venous oxygen saturation in infants after cardiac surgery

Continuous mixed venous oxygen saturation SvO2c was measured in 16 infants immediately after cardiac surgery. A polyurethane 4F, dual channel catheter (Opticath, Modell U440, Oximetrix) with fiberoptic filaments was introduced into the pulmonary artery during cardiothoracic surgery. The catheters were left in place for an average of 67.5 h (range 27 h – 125 h) and there were no catheter-related complications. Correlation between continuous in vivo SvO2 values and in vitro values was satisfactory (r=0.85), whereas a correlation between SvO2c and arterial oxygen saturation (SaO2) was not found (r=0.07). The sampled arterial lactate values were inversely correlated to the simultaneously measured SvO2c, but the corelation coefficient was only r=-0.4. There was an inverse correlation between SvO2c and arteriovenous oxygen content difference (Ca−vDO2c) (r=-0.82), and a marked inverse correlation to the calculated oxygen utilization ratio (r=-0.97). Therefore SvO2c continuously reflects the overall balance between oxygen consumption and delivery, but the use of SvO2 as a predictor of blood lactate levels is unreliable. A further purpose of the present study was to demonstrate the clinical applications and to show the usefulness of SvO2c-monitoring; particularly as a surveillance and early warning system, as a guide for assessing therapy and its relevance in interpreting other monitored parameters. In our opinion continuous SvO2 measurement is a reliable and valuable indicator of cardiopulmonary function in the immediate post-operative period, even in infants with complicated repair of cardiac malformations.

Hemodynamic effects of dobutamine in children with cardiovascular failure.

The effect of dobutamine, a synthetic catecholamine, was studied in 12 patients aged one day to 14 years with low cardiac output syndromes.After initial stabilization of the patients dobutamine was administered by continuous infusion in a dosage of 7.5 or 10 μg/kg/min.Heart rate, cardiac output (using thermodilution technique and/or pulse contour method), mean systemic and mean pulmonary artery pressures were determined before and after the dobutamine infusion. Systemic and pulmonary vascular resistances, cardiac index and stroke volume index were calculated.Cardiac output and cardiac index increased significantly in every patient, whereas the heart rate changed only slightly, suggesting that the increase in cardiac output was mainly due to the alteration of stroke volume. The mean arterial pressure increased significantly, but the mean pulmonary artery pressure was unchanged. No side effects were observed during the dobutamine infusion. Dobutamine is a potent inotropic drug with limited chronotropic and peripheral vascular effects in newborns, infants and chidren.

Evaluation of the Valve Area Underestimation by the Continuity Equation

During the last years, noninvasive determination of the aortic valve area by Doppler echocardiography using the continuity equation became popular. However, a systematic valve area underestimation of about 15% compared to invasive measurements using the Gorlin formula has been reported. The cause therefore is unknown. The purpose of this study was to evaluate whether the valve area underestimation by the Doppler method might be due to differences in the hydrodynamic background of both methods. This comparison is facilitated by the fact that the Gorlin formula is based on the continuity equation. Compared to the continuity equation, there are four changes within the Gorlin formula: (1) the additional use of a discharge coefficient, which leads to valve area overestimation by the factor 1.17; (2) neglect of the pre-stenotic velocity, causing further overestimation by the factor 1.036 (in mild stenosis this factor may be 1.18 and more); (3) the wrong calculation of the mean pressure drop, which leads to a mean change by the factor 0.95, and (4) the incorrect substitution of the height by the pressure drop in the derivation of the Gorlin formula causes underestimation by the factor 0.97. Combining these four factors results in valve area overestimation of the Gorlin formula compared to the continuity equation by the factor 1.12. This explains to a large extent the valve area underestimation by the continuity equation.

The effect of nifedipine alone or combined with low dose acetylsalicylic acid on endotoxin-induced pulmonary hypertension in the piglet

Cardiovascular responses to the calcium antagonist nifedipine, alone and combined with low dose acetylsalicylic acid (ASA), were evaluated in a piglet model of endotoxin-induced pulmonary hypertension. All animals were anesthetized, paralyzed and mechanically ventilated. Cardiac output (CO), pulmonary artery pressure (PAP), aortic blood pressure (SAP), pulmonary capillary wedge pressure (PCWP), right strial pressure (RAPM) and arterial blood gases were measured before and after induction of pulmonary hypertension by E. coli endotoxin and after treatment. Results of treated groups were compared to a control group of piglets subjected to the same dose (0.15 μg/kg i.v.) of endotoxin. Control animals responded to a bolus injection of endotoxin within 15 min with an increase in mean PAP by 110%. Pulmonary vascular resistance (PVR) increased by 144%. Mean arterial pressure did not change significantly from baseline values. In animals treated with a single dose of 1 mg/kg ASA prior to endotoxin, the initial pulmonary response was not quantitatively different from control values, whereas ASA 20 mg/kg abolished the pulmonary vascular reaction. The increase of systemic vascular resistance (SVR) produced by endotoxin was aggravated by high dose ASA. In piglets treated with nifedipine (4 μg/kg/min) over 30 min after the application of endotoxin with and without additional infusion of nifedipine 60 min prior to endotoxin the PVR could be attenuated. The combination of nifedipine and low dose ASA showed synergistic effects compared to control. The increase of mean PAP was significantly reduced, the PVR remained in base-line range due to a marked elevation of cardiac output.

Die myokardiale Sarcoidose

ZusammenfassungEine nicht unerhebliche, aber klinisch selten beschriebene Komplikation der Sarc. ist der Befall des Myokards. Je nach Lokalisation des Krankheitscherdes kommt es dabei zu Herzrhythmusstörungen, Störungen des Erregungsablaufes oder zur allgemeinen kardialen Insuffizienz. Über einen Fall mit myokardialer Sarc. wird berichtet. Häufige EKG-Kontrollen können eine rechtzeitige Behandlung dieser Komplikation gewährleisten.SummaryParticipation of the myocardium in sarcoidosis has been rarely described, but is nevertheless an important complication of this disease. Depending upon the localisation of the focus of the disease, disturbances of heart rhythm and of conduction or general heart insufficiency are observed. A case of sarcoidosis of the myocardium is reported. Frequent controls of the electrocardiogram may warrant speedy treatment of this complication.Eine nicht unerhebliche, aber klinisch selten beschriebene Komplikation der Sarc. ist der Befall des Myokards. Je nach Lokalisation des Krankheitscherdes kommt es dabei zu Herzrhythmusstorungen, Storungen des Erregungsablaufes oder zur allgemeinen kardialen Insuffizienz. Uber einen Fall mit myokardialer Sarc. wird berichtet. Haufige EKG-Kontrollen konnen eine rechtzeitige Behandlung dieser Komplikation gewahrleisten.

Congenital mitral regurgitation caused by a perforation in the anterior leaflet: Perioperative evaluation by color-coded Doppler echocardiography

SummaryColor-coded two-dimensional (2D) echocardiography confirmed the presence of severe congenital mitral regurgitation in an 8-month-old infant. Intraoperative inspection revealed an isolated perforation in the anterior leaflet.

Kontinuierliche EEG-Ableitung unter submaximaler fahrradergometrischer Belastung epilepsiekranker Kinder

Dreisig epilepsiekranke Kinder wurden unter kontinuierlicher EEG-Ableitung einer fahrradergometrischen Belastung unterzogen. Patienten mit einer primar generalisierten Epilepsie (acht Kinder) zeigten keine pathologischen Veranderungen. Vier von siebzehn Kindern mit einer focalen Epilepsie und zwei von funf mit einer sekundar generalisierten Epilepsie wiesen eine Verschlechterung unter Belastung auf. Hypersynchrone Aktivitaten traten besonders bei den Kindern auf, deren letzter Anfall weniger als zwei Wochen zurucklag. Ein Krampfanfall wurde bei keinem Kind ausgelost. Die individuelle Beurteilung der Sportfahigkeit mus die Epilepsieform und die Anfallshaufigkeit berucksichtigen. Wahrend der medikamentosen Einstellung ist vom Schulsport abzuraten. Durch die korperliche Belastung wird die Krampfbereitschaft nicht erhoht.

Untersuchungen über die Beurteilung der Hautdurchblutung durch zentrale und periphere Temperaturmessungen

Zur Diagnose und Therapie eines Schockgeschehens sind neben zentralen Parametern auch Angaben uber die periphere Durchblutung notwendig. Das am einfachsten zu erreichende Capillargebiet ist das der Haut. Die Hautdurchblutung stellt den wichtigsten Regulator fur den Warmestrom dar, so das ein Zusammenhang zwischen Hauttemperatur und Hautdurchblutung zu erwarten ist. Vergleiche der tatsachlichen Hautdurchblutung gemessen durch Δλ mit verschiedenen Hauttemperaturen, integrierte Hauttemperatur und Burton-Indices liesen keinen Zusammenhang erkennen. Jedoch ist die Korrelation mit der Rectum-Zehen-Temperaturdifferenz ΔT statistisch hoch signifikant. Sie kann ohne technischen Aufwand als orientierendes Mas der Hautdurchblutung in der Diagnose des Schocks eingesetzt werden.Diagnosis and therapy of shock necessitates precise information on the peripheral blood flow as well as consideration of parameters relating to the central circulatory condition. The skin is the capillary area of easiest access. Peripheral circulation implies the most effective regulating system in heat transport; therefore one may expect a relationship between skin temperature and skin blood flow. Comparisons of the blood flow through the skin, as recorded by means of a Hensel Fluvograph and ascertained as Δλ, with the actual skin temperature (average skin temperature; Burton indices) did not reveal any correlation. The correlation with the difference between rectal and big toe temperature, however, is statistically highly significant. The determination of the proportion between the two values (rectal versus big toe temperature) can be used without technical difficulties as an orienting measure of skin blood flow in the diagnosis of shock.ZusammenfassungZur Diagnose und Therapie eines Schockgeschehens sind neben zentralen Parametern auch Angaben über die periphere Durchblutung notwendig. Das am einfachsten zu erreichende Capillargebiet ist das der Haut. Die Hautdurchblutung stellt den wichtigsten Regulator für den Wärmestrom dar, so daß ein Zusammenhang zwischen Hauttemperatur und Hautdurchblutung zu erwarten ist. Vergleiche der tatsächlichen Hautdurchblutung gemessen durch Δλ mit verschiedenen Hauttemperaturen, integrierte Hauttemperatur und Burton-Indices ließen keinen Zusammenhang erkennen. Jedoch ist die Korrelation mit der Rectum-Zehen-Temperaturdifferenz ΔT statistisch hoch signifikant. Sie kann ohne technischen Aufwand als orientierendes Maß der Hautdurchblutung in der Diagnose des Schocks eingesetzt werden.