Felix Wyler

Exercise-induced hypertension in the arms due to impaired arterial reactivity after successful coarctation resection

Exercise-induced hypertension of the arms is a well-known late complication after coarctation repair. Residual narrowing at the anastomosis site as well as abnormalities of the precoarctation arterial system may be the cause of this problem. Blood pressure response to exercise and flow-mediated arterial dilatation of the arms and legs were studied in 29 young adults after successful coarctectomy in childhood and compared with 13 control subjects. Peak exercise systolic blood pressure was significantly higher in patients than in control subjects: 238 versus 199 mm Hg (p = 0.007). Both groups had a positive systolic arm-leg gradient during exercise: 59 versus 37 mm Hg (p = 0.05). Flow-mediated dilatation of the brachial artery was significantly reduced in patients compared with that in control subjects: 4.2% (range 0% to 9.4%) versus 9.4% (range 3.7% to 16%) (p < 0.0001). Flow-mediated dilatation of the femoral artery was similar in both groups. Dilatation of the brachial artery was inversely correlated to peak exercise systolic pressure in the study patients (r = -0.427, p = 0.02). A positive arm-leg exercise gradient partly represents physiologic circulatory adaptation to ergometry and is therefore not appropriate for evaluation of residual narrowing. Exercise-induced hypertension of the arms late after coarctation repair is caused by impaired arterial reactivity, which results from structural or functional abnormality, or both.

Validation studies for the use of the microsphere method in cats and young minipigs

SummaryRadioactive microspheres are suitable for measuring cardiac output, its distribution and organ blood flow if certain criteria are met. Cardiac output may be determined with the reference flow method if microspheres do not recirculate. In cats 10 μm microspheres were extracted completely by the lungs. The use of microspheres for the determination of cardiac output is therefore not limited by recirculation of microspheres down to this size.Under baseline conditions we found no preferential streaming with 50 μm spheres in young minipigs and with 25 and 15 μm spheres in cats. At high cardiac output values induced by the administration of 0.4 mg/kg of Dihydralazine to cats, 25 μm but not 15 μm microspheres showed a small, non significant tendency to stream preferentially into the upper body. Thus, under rapid flow conditions 15 μm microspheres may be preferable to larger ones from the rheological point of view.Under baseline conditions the distribution of cardiac output to a wide range of organs was very similar when comparing 25 and 15 μm microspheres in cats and 50 and 15 μm microspheres in minipigs, whereas 10 μm microspheres were poorly extracted by most organs in cats. 15 μm microspheres were found to be suitable for the determination of cardiac output and its distribution in both species provided that bronchial and arteriovenous shunt flows can be neglected.ZusammenfassungEs werden die Voraussetzungen beschrieben, unter denen radioaktive Mikrosphären bei der Katze und dem Zwergschwein zur Messung des Herzminutenvolumens (HMV) und dessen Aufteilung angewendet werden können.Bei narkotisierten Katzen extrahierte das pulmonale Gefäßbett Mikrosphären von 10 μm Durchmesser vollständig, so daß das HMV damit gemessen werden darf.Zentrifugationseffekte im Aortenbogen ließen sich bei keiner Spezies weder mit 50 noch mit 25 und 15 μm nachweisen. Bei erhöhtem HMV dürften kleine Mikrosphären ein günstigeres Strömungsverhalten zeigen.Die periphere Aufteilung des HMV wurde mit 25-, 15- und 10-μm Mikrosphären bei der Katze und mit 50- und 15-μm Mikrosphären beim jungen Zwergschwein gemessen. Für die meisten Organe ergaben sich mit 15- und 25-respektive 50-μm-Mikrosphären vergleichbare Werte. Wesentlich tiefere Werte wurden mit 10-μm-Kügelchen erhalten, so daß angenommen werden darf, daß diese von den meisten Organen nicht vollständig aus dem Blut extrahiert werden. Sie sind deshalb bei Katzen nicht geeignet, um die Aufteilung des Herzminutenvolumens oder Organdurchblutungen zu messen.

Das Göttinger Miniaturschwein als Versuchstier

In 16 juvenile minipigs weighing 3.08 kg an average cardiac output of 23 ml/100 g body weight was measured with the dye-dilution method. The microsphere technique was used to assess distribution of cardiac output and organ blood flow. In 12 adult minipigs with a mean body weight of 21.5 kg the cardiac output of 14 ml/100 g body weight was measured with an electromagnetic flowmeter. The values of total systemic and organic blood flow correlated well with those of man and partly with those of other laboratory animals.

Effect of general anesthesia on distribution of cardiac output and organ blood flow in the rabbit: halothane and chloralose-urethane.

THE MAJOR CIRCULATORY ACTIONS of general anesthetics are known to consist in reduction of the myocardial contractile force and in changes in the neurogenic control of the vascular tone [ 131. The hypotensive effect of halothane is attributed partly to a reduced cardiac output and partly to a diminished arterial vascular resistance [ 5, 6, 131. Chloralose-urethane, however, is known to interfere little with cardiovascular reflexes and to produce anesthesia without significant arterial hypotension [ 51. Whereas halothane is widely used in clinical medicine, chloralose-urethane alone or after halothane induction is the anesthetic of choice when circulatory control mechanisms are studied experimentally [5, lo]. In view of their different effects on arterial pressure and cardiac output, it was thought interesting to investigate the reaction of all the individual vascular beds and to measure their contribution to these hemodynamic changes. When radioactively labelled microspheres are injected into the left ventricle as a bolus they are distributed to the body with blood flow and provide a method for measuring the distribution of cardiac output to all organs. This technique has been

Effects of Hypoxia on Distribution of Cardiac Output and Organ Blood Flow in the Rabbit

The hemodynamic responses of various vascular beds in the systemic circulation to prolonged moderate hypoxia were studied in the rabbit using the radioactive microsphere method. Although cardiac output remained unchanged, there was a redistribution of blood flow in which blood was mainly diverted from the kidneys to provide greater supply to heart, brain and skeletal muscle. These regional adjustments are similar to those seen after low cardiac output due to hemorrhage or endotoxic shock.

Late Follow‐up of Patients Who Underwent Palliation for Complex Congenital Heart Disease in Childhood

We report on a series of 12 patients with complex congenital heart disease who had reached adult life after surgical palliation in early childhood and who were systematically followed by clinical visits. Patients were born between 1953 and 1979 and were followed up into 2007. All patients had complex lesions with single ventricle physiology and were palliated either by banding of the pulmonary artery or by creation of systemic-pulmonary shunts. Single operations were performed in 4 cases, and 8 patients had 1 or more further palliative interventions. Late corrective surgery and heart transplantation were performed in 1 patient each. Eight survivors reached a mean age of 36 years at follow-up (range 28-48), whereas 4 patients died at a mean age of 32 years (range 22-53). All patients were in New York Heart Association classes II and III. Complications during follow-up were bacterial endocarditis (3), cerebrovascular accidents (3), arrhythmias (3), need for pacemakers (2). Deaths occurred perioperatively at transplant (1), or were caused by sudden death (2), and hypoxia related to fall in blood pressure (1). Successful pregnancies occurred in 3 patients with healthy (small) babies delivered by cesarean section in 2 of them, and vaginal delivery in 1. The course of life in these patients shows not only a wide spectrum with good quality of life in some of them but also a large number of potentially severe complications. Survival beyond 50 years is rare.

Endotoxin induced regional circulatory reactions in the rabbit with and without halothane anesthesia

Abstract Distribution of cardiac output, individual organ blood flow, and vascular resistance was investigated in endotoxic shock in the rabbit. The unanesthetized animal and the animals under Halothane anesthesia showed the same pattern of regional circulatory response: unchanged or decreased vascular resistance to flow to brain, heart, eye; intense elevation of resistance in kidneys, spleen, fat, and skin; intermediate reaction of gastrointestinal tract and muscle. Halothane affected the extent of the individual regional changes and not their type. It is suggested that the different hemodynamic reaction of laboratory animal and man to endotoxin is mainly caused by the species-specific local response of the various vascular beds.

Hemodynamics in Experimental Hypernatremic Dehydration with Special Reference to Individual Organ Blood Flow in Shock and after Rehydration

Summary: Shock after hypernatremic dehydration in the mini-pig is characterized by low cardiac output but little reduction of arterial blood pressure. Maintenance of pressure is due to extensive arteriolar vasoconstriction in the splanchnic and renal vascular bed, as calculated from their markedly diminished blood flow. The expected preservation of flow to vital organs did occur in the brain and the adrenals, but not in the heart. Sufficient oxygen was probably provided by the elevated hematocrit.After 24 h, intravenous fluid therapy produced adequate rehydration as seen from the correction of azotemia, metabolic acidosis, and hypernatremia; only serum creatinine remained elevated. Although cardiac output increased, it did not reach the initial value. Blood flow to most organs was back to normal, but gastrointestinal and particularly renal blood flow remained diminished.

COR TRIATRIATUM IN A 3 MONTH OLD INFANT An operable form of pulmonary hypertension

ABSTRACT. Wyler, F., Rutishauser, M. and Grädel, E. (Childrens Hospital and Department of Heart Surgery, University of Basel, Switzerland). An operable form of pulmonary hypertension: Cor triatriatum in a 3‐month‐old infant. Acta Paediatr Scand, 63: 619, 1974. —In a 3‐month‐old infant the clinical picture and the diagnostic criteria of cor triatriatum are presented. In addition to the pressure differences between PC wedge and left atrium the angiocardiogram is pertinent for detecting this malformation. This easily operable condition should be included in the differential diagnosis in every case of pulmonary hypertension from elevated pulmonary venous pressure. This is, to our knowledge, the youngest patient reported with correct preoperative diagnosis and surgical cure.

Regional vascular responses to asphyxia in the rabbit.

Abstract. Organ blood flow was measured in eight spontaneously breathing male New Zealand white rabbits exposed to a 50 min period of asphyxia. The results were compared with eight control animals. Cardiac output and arterial pressure did not change. There was increased flow to the heart, brain and diaphragm. Flow to the kidneys and adipose tissue was reduced. Flow to the gastro‐intestinal tract, liver, skeletal muscle and carcass was unchanged. Prolonged moderate asphyxia produces preferential blood supply to vital organs and maintains flow to the skeletal musculature and the gastro‐intestinal tract; their blood supply is diverted mainly from the kidneys. These changes are similar to those seen in haemorrhagic and endotoxic shock in the rabbit.