Acid-Base Derangements and Myocardial Contractility

Thrower, Wendell B.; Darby, Thomas D.; Aldinger, Earl E.

doi:10.1097/00132586-196204010-00026

Cited by 12 publications

(12 citation statements)

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“…Other investigations which have examined the effectiveness of injections or infusions of catecholamines during acidaemia have been completed in animals with the efferent autonomic nerves to the heart intact; in these investigations there may be a reduced response of the heart to catecholamines during acidaemia. The increase in myocardial contractile force has been used as an index of a positive inotropic response and this increase in response is diminished during acidaemia (Thrower, Darby & Aldinger, 1961;Manley, Woodbury & Nash, 1966). Myocardial contractile force, however, as determined using a strain-gauge arch sutured on to the ventricular muscle, may change with the dilatation of the heart which accompanies the acidaemia and changes in the force may not be a valid index in these circumstances (Cotten, 1953).…”

Section: Discujssionmentioning

confidence: 99%

The effect of acidaemia on the response to stimulation of the autonomic nerves to the heart

Norman¹

1969

The Journal of Physiology

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SUMMARY1. The effects are described of an acidaemia produced either by an inhalation of carbon dioxide or by an infusion of hydrochloric acid on the response of the heart to stimulation of the ansae subclaviae and right vagus nerve in anaesthetized dogs.2. The results show that during an acidaemia (pH 6.95) of up to 2 hr duration the response to stimulation of the right vagus nerve was enhanced and that the inotropic response to stimulation of sympathetic nerves was not changed; the chronotropic response was depressed during acidaemia only at the low end of the range of responses, from 0 to 40 beats/ min. The importance of preventing acidaemia when investigating reflex heart rate responses is discussed.3. It is suggested that in the intact animal with an innervated heart the response of the heart to stimulation of the sympathetic nerves is unaltered in acidaemia and that the reported effects of changed cardiovascular response during acidaemia may in part be explained by the enhanced response to vagal stimulation and an altered response of the peripheral vessels.

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Section: Discujssionmentioning

confidence: 99%

The effect of acidaemia on the response to stimulation of the autonomic nerves to the heart

Norman¹

1969

The Journal of Physiology

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“…Underlining this, Kohlhardt et al described already in the 1960s a significant, moderateacidosisinduced cardiac output decrease in nonfailing cats by 25% (pH = 7.00) (13). Further investigations on acidosis-induced decrease of myocardial contractility and its effect on catecholamine response were performed using different approaches and models (14)(15)(16)(17)(18)(19)(20)(21)(22); however, there still exist no experimental data describing the specific effect of metabolic acidosis in isolated ovine hearts even though sheep are widely used as animal models (23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41).…”

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confidence: 99%

Influence of Mild Metabolic Acidosis on Cardiac Contractility and Isoprenaline Response in Isolated Ovine Myocardium

Schotola¹,

Sossalla²,

Rajab

et al. 2011

Artificial Organs

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The postoperative course after major surgical procedures such as cardiothoracic operations is often accompanied by acute metabolic abnormalities due to large volume and temperature shifts. In general, those intervention-induced trauma might cause the use of catecholamines to stabilize hemodynamics. Within the cardiac community, there are still controversial discussions about standardized medical therapy to treat postoperative acidosis, for example, buffering versus nonbuffering for improving catecholaminergic response of myocardial contractility. The aim of this study was to investigate the influence of mild (and thus clinically relevant) acidosis on myocardial contractility and catecholamine response in explanted trabeculae of ovine hearts. Intact trabeculae (n = 24) were isolated from the right ventricle of healthy sheep hearts. Two different groups (group 1: pH = 7.40, n = 9 and group 2: pH = 7.20, n = 13) were investigated, and force amplitudes were measured at frequencies between 30 and 180 beats per minute and increasing catecholamine concentrations (isoprenaline 0-3 × 10(-6) mM). Force-frequency relation experiments in the presence of a physiological and/or mild acidotic pH solution showed no significant differences. Mean force amplitudes normalized to the lowest frequency showing no significant differences in force development between 0.5 and 3 Hz (n = 9 vs. 13, P = n.s.) (0.5 Hz absolute values 3.1 ± 2.6 for pH = 7.40 vs. 3.8 ± 2.6 mN/mm(2) for pH = 7.20, P = n.s.). Moreover, there was no significant difference in relaxation kinetics between the two groups. Furthermore, the experiments showed similar catecholamine responses in both groups. Force amplitudes normalized to baseline and maximum force showed no significant differences in force development between baseline and maximum isoprenaline concentrations (n = 6 vs. 9, P = n.s.) (baseline absolute values 4.3 ± 4.0 for pH = 7.40 vs. 3.9 ± 1.2 mN/mm(2) for pH = 7.20, P = n.s.). Additionally, relaxation kinetics did not show differences after catecholamine stimulation. The presented experiments revealed no significant negative inotropic effects on isometrically contracting ovine trabeculae with mild metabolic acidosis (pH = 7.2) compared with physiological pH (7.4). Additionally, similar catecholamine responses were seen in both groups. Further investigations (e.g., in vivo and/or in failing hearts with reduced compensatory reserves) will be necessary to examine optimal medical treatment for metabolic abnormalities after cardiac surgery.

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“…Few patients survive prolonged depression of the blood pH below 70 (Siggaard- Anderson, 1963). Thrower, Darby & Aldinger (1961) showed that if acidosis persists a stage may be reached when death will ensue despite correction of the underlying metabolic disturbance. Enzyme activity may be impaired by a drop in pH (Barness, 1959).…”

Section: Discussionmentioning

confidence: 99%