Inotropic responses of the left ventricle to changes in aortic arch pressure in anaesthetized dogs

1. The aims of this study were 1) to determine whether the impulse activity in rabbit aortic baroreceptors (BRs) was influenced by changes in nonpulsatile flow through the aortic lumen and 2) to examine the BR and aortic arch responses to changes in temperature. 2. An in vitro aortic arch-aortic nerve preparation was used to record suprathreshold steady-state discharge in a total of 29 single-unit BRs from 12 New Zealand white rabbits. Changes in BR frequency were measured relative to control and were recorded simultaneously with aortic arch pressure, flow, temperature, diameter, and calculated wall shear stress (Sw). 3. With pressure held constant, stair-step increases in flow (3–18 ml/min) constricted the arch and evoked two types of BR responses: activation in most units (15 of 17 BRs tested) and inhibition in 2 units. The activation response appeared closely related to the changes in flow and Sw, but also appeared related to uncontrolled changes in perfusate temperature. 4. When the effects of temperature were examined more closely with pressure and flow held constant, controlled step increases in temperature (between 32 and 42 degrees C) constricted the arch and again evoked two BR responses: activation in 11 of 14 BRs tested and inhibition in 3 units. The Q10 for the activation response was 1.55 +/- 0.08 (mean +/- SE), which was not significantly different from the Q10 for activation when temperature varied with flow (1.65 +/- 0.1, P < 0.05). Thus the effect of temperature on most BRs was directionally and quantitatively similar in the presence and absence of changes in flow. 5. Last, when flow was examined over a wide range (15–515 ml/min) with temperature and pressure held constant, stair-step increases in flow failed to produce any change in BR frequency in each of 15 fibers tested (10 arches). The lack of response was not due to a functionally damaged preparation because the usual BR and aortic arch responses to pressure and to drug-evoked vasoconstriction (norepinephrine) and endothelial-mediated vasodilation (acetylcholine) were intact. 6. These results demonstrate that aortic BRs in rabbits are not sensitive to flow and thus are not likely influenced by fluctuations in cardiac output apart from associated changes in pressure. The aortic BRs are affected directly by variations in temperature and in some cases indirectly by temperature-related vasoconstriction. The effects of temperature may have important implications for neural control of the circulation when core temperature varies because of physiological and environmental stress.

Download Full-text

Aortic arch reflex control of total systemic vascular capacity

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1987.253.3.h598 ◽

1987 ◽

Vol 253 (3) ◽

pp. H598-H603

Author(s):

A. A. Shoukas ◽

M. J. Brunner ◽

A. S. Greene ◽

C. L. MacAnespie

Keyword(s):

Arterial Pressure ◽

Aortic Arch ◽

Carotid Sinus ◽

Peripheral Resistance ◽

Systemic Arterial Pressure ◽

Reservoir Volume ◽

Aortic Arch Pressure ◽

Pressure Changes ◽

Change In Mean ◽

Sinus Pressure

The ability of the aortic arch baroreceptors to change vascular capacity was measured and, in the same animal, compared with carotid sinus reflex changes in capacity. Seven dogs were anesthetized with pentobarbital sodium and perfused with constant flow. Changes in external reservoir volume reflected reciprocal changes in total systemic vascular capacity and changes in arterial pressure parallel changes in total peripheral resistance. The aortic arch and carotid sinus baroreceptor areas were isolated, and the pressures were controlled separately. With carotid sinus pressure held constant at 125 mmHg, aortic arch pressure was increased and decreased between 225 and 50 mmHg, and the changes in reservoir volume and systemic arterial pressure were measured. Results from increasing and decreasing aortic arch or carotid sinus pressure were not significantly different and were averaged. The mean change in reservoir volume was 1.9 +/- 0.2 ml/kg and the change in mean arterial pressure was 18.7 +/- 3.7 mmHg. The changes in reservoir volume and arterial pressure caused by the aortic arch reflex were not influenced by the level of carotid sinus pressure. Carotid sinus pressure changes between 200 and 50 mmHg at a constant aortic arch pressure caused reservoir volume and arterial pressure to change by 7.2 +/- 0.9 ml/kg and 45.1 +/- 4.1 mmHg, respectively. The level of aortic arch pressure did not modify these responses.

Download Full-text

Case report: duct dependency in hypoplastic left heart complex can be reversible without surgery

Cardiology in the Young ◽

10.1017/s1047951120003935 ◽

2020 ◽

pp. 1-4

Author(s):

Abdullah N. Alhuzaimi

Keyword(s):

Case Report ◽

Left Ventricle ◽

Aortic Arch ◽

Loading Condition ◽

Left Heart ◽

Hypoplastic Left Heart ◽

Resource Limitations ◽

Hypoplastic Left Heart Complex

Abstract We describe an infant with duct-dependent hypoplastic left heart complex with moderate hypoplasia of the left ventricle and aortic arch who was not operated due to resource limitations. The left-sided structures grew remarkably due to favourable loading condition changes of the left ventricle, allowing weaning from prostaglandin at the age of 3 months and discharging the patient without intervention.

Download Full-text

Influence of intrauterine hemodynamics on the C segment of the aortic arch in the fetus

Rossiyskiy Vestnik Perinatologii i Pediatrii (Russian Bulletin of Perinatology and Pediatrics) ◽

10.21508/1027-4065-2021-66-4-45-52 ◽

2021 ◽

Vol 66 (4) ◽

pp. 45-52

Author(s):

G. G. Hubulava ◽

S. P. Marchenko ◽

A. B. Naumov ◽

U. A. Strupeneva ◽

E. S. Kulemin ◽

...

Keyword(s):

Aortic Valve ◽

Left Ventricle ◽

Stroke Volume ◽

Aortic Arch ◽

Pearson Correlation ◽

Left Ventricular ◽

End Diastolic Volume ◽

Brachiocephalic Trunk ◽

Hemodynamic Characteristics ◽

Fisher’S Criterion

Objective. To assess the correlation between the hemodynamic characteristics of the left ventricle and geometric features of the aortic arch in the fetus.Methods. The study involved 31 fetuses from 29 to 34 weeks of gestation by echocardiography. The scientists assessed the morphogeometric characteristics of the left ventricle andaortic arch. They studied the following parameters: end-diastolic volume ofthe left ventricle (LVEDV), stroke volume of the leftventricle (LVSV), velocity-time integral of the flow through aortic valve (VTI AV), diameter of the aortic valve ring (AV), diameterof the aortic arch segment between brachiocephalic trunk and left carotid artery (dС). Results. The average gestational age was 31,9±1,4weeks (95% CI: 31,4–32,4 weeks). Average body weight 1899±377 g (95% CI: 1762–2038 g). LVEDV = 1,57±0,64 ml (95% CI: 1,3–1,8). LVSV = 1,3±0,45 ml (95% CI: 1,1–1,4 ml). AV 0,4±0,07 cm (95% CI: 0,39–0,44 cm). C segment of the aorticarc is 0,37±0,07 cm (95% CI: 0,035–0,040 cm). There was direct correlation between the variables used to calculate dC (Pearson correlation coefficient: LVEDV = 0,51; p=0,002; LVSV = 0,46; p=0,005; AV = 0,52, p=0,001). The diameter of the C segment of the aortic arch can be calculated using the following equations: dС= 0,76· LVSV +2,8 (95% CI LVSV 0,2–1,3 95% CI for constant2,1–3,6; Fisher’s criterion 7,6 р=0,01). dС= 0,59· LVEDV +2,8 (95% CI LVEDV 0,2–0,98; 95% CI for constant 2,2–3,5; Fisher’s criterion 10 р=0,004). dС= 0,59·AV+1,3 (95% CI AV 0,22–0,95; 95% CI for constant – 0,23–2,9; Fisher’s criterion 10,7;р=0,003).Conclusion. 1)hemodynamic characteristics of the left ventricle allow predicting the sizeof the aortic arch in fetuses from 29 to 34 weeks of gestation; 2)morphogeometric characteristics of the aortic arch are determined by the characteristics of the left ventricular stroke volume, end-diastolicvolume of the leftventricleand the sizeof the fibrous ring of the aortic valve.

Download Full-text

Echocardiographic predictors of reoperation for subaortic stenosis in children and adults

European Journal of Cardio-Thoracic Surgery ◽

10.1093/ejcts/ezz046 ◽

2019 ◽

Vol 56 (3) ◽

pp. 549-556

Author(s):

Paraskevi Theocharis ◽

Nicola Viola ◽

Nikolaos D Papamichael ◽

Markku Kaarne ◽

Tara Bharucha

Keyword(s):

Aortic Valve ◽

Left Ventricle ◽

Aortic Arch ◽

Significant Proportion ◽

Interrupted Aortic Arch ◽

Left Ventricular ◽

University Hospital ◽

Subaortic Stenosis ◽

Corrective Surgery ◽

Predictors Of Recurrence

Abstract OBJECTIVES Subaortic stenosis (SAS) can present as various types of obstruction of the left ventricular outflow tract (LVOT) below the level of the aortic valve. Even though corrective surgery has been identified as the most effective treatment, SAS more frequently reoccurs requiring reoperation in a significant proportion of the patients. Previous studies have focused on predictors of recurrence in various subgroups of patients with SAS, but rarely in the overall population of patients with SAS. The aim of this study was to determine the predictors of recurrence of SAS after initial corrective surgery. METHODS Patients from the database of the Congenital Cardiology Department of the University Hospital of Southampton with significant SAS requiring corrective surgery were included in the study. Data retrieved were obtained and used to determine the predictors of SAS recurrence after the initial corrective surgery. RESULTS Eighty-two patients (paediatric, n = 72 and adult, n = 10) who underwent initial successful resection were included in the analysis. Thirty patients required reoperation for recurrent SAS. These were significantly younger (median age 3.0 vs 6.7 years, P = 0.002). The recurrence of SAS was more common in patients with an interrupted aortic arch (23.3% vs 3.8%, P = 0.010) and unfavourable left ventricle geometry (43.3% vs 7.6%, P < 0.001), with steeper aortoseptal angle (131.0° ± 8.7° vs 136.1° ± 8.6°, P = 0.030), shorter distance between the point of obstruction of the LVOT and the aortic valve annulus in systole and diastole (median 4.30 vs 5.90 mm, P = 0.003 and 3.65 vs 4.95 mm, P = 0.006, respectively) and in those who had higher residual peak and mean LVOT gradients postoperatively (29.3 ± 16.0 vs 19.8 ± 10.7 mmHg, P = 0.006 and 15.9 ± 8.3 vs 10.1 ± 5.8 mmHg, P = 0.002, respectively). Overall, the presence of an interrupted aortic arch [odds ratio (OR) 10.34, 95% confidence interval (CI) 1.46–73.25; P < 0.019] and unfavourable left ventricle geometry (OR 10.42, 95% CI 1.86–58.39; P < 0.008) could independently predict reoperation for SAS after initial successful resection. CONCLUSIONS Patients who have initial corrective surgery for SAS at a younger age, unfavourable left ventricle geometry, an interrupted aortic arch and higher early postoperative LVOT gradients are more likely to have recurrent SAS requiring reoperation.

Download Full-text

Functional and anatomical variability of canine cardiac sympathetic efferent pathways: implications for regional denervation of the left ventricle

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y86-165 ◽

1986 ◽

Vol 64 (7) ◽

pp. 958-969 ◽

Cited By ~ 15

Author(s):

R. D. Janes ◽

D. E. Johnstone ◽

J. C. Brandys ◽

J. A. Armour

Keyword(s):

Left Ventricle ◽

Stellate Ganglion ◽

Left Ventricular ◽

Efferent Innervation ◽

Cardiac Nerve ◽

Cervical Ganglion ◽

The Right ◽

Inotropic Responses ◽

Left Middle ◽

Cardiac Nerves

To further elucidate the functional anatomy of canine cardiac innervation as well as to assess the feasibility of producing regional left ventricular sympathetic denervation, the chronotropic and (or) regional left ventricular inotropic responses produced by stellate or middle cervical ganglion stimulation were investigated in 22 dogs before and after sectioning of individual major cardiopulmonary or cardiac nerves. Sectioning the right or left subclavian ansae abolished all cardiac responses produced by ipsilateral stellate ganglion stimulation. Sectioning a major sympathetic cardiopulmonary nerve, other than the right interganglionic nerve, usually reduced, but seldom abolished, regional inotropic responses elicited by ipsilateral middle cervical ganglion stimulation. Sectioning the dorsal mediastinal cardiac nerves consistently abolished the left ventricular inotropic responses elicited by right middle cervical ganglion stimulation but minimally affected those elicited by left middle cervical ganglion stimulation. In contrast, cutting the left lateral cardiac nerve decreased the inotropic responses in lateral and posterior left ventricular segments elicited by left middle cervical ganglion stimulation but had little effect on the inotropic responses produced by right middle cervical ganglion stimulation. In addition, the ventral mediastinal cardiac nerve was found to be a significant sympathetic efferent pathway from the left-sided ganglia to the left ventricle. These results indicate that (i) the stellate ganglia project axons to the heart via the subclavian ansae and thus effective sympathetic decentralization can be produced by cutting the subclavian ansae; (ii) the right-sided cardiac sympathetic efferent innervation of the left ventricle converges intrapericardially in the dorsal mediastinal cardiac nerves; and (iii) the left-sided cardiac sympathetic efferent innervation of the left ventricle diverges to innervate the left ventricle by a number of nerves including the dorsal mediastinal, ventral mediastinal, and left lateral cardiac nerves. Thus consistent denervation of a region of the left ventricle can not be accomplished by sectioning an individual cardiopulmonary or cardiac nerve because of the functional and anatomical variability of the neural components in each nerve, as well as the fact that overlapping regions of the left ventricle are innervated by these different nerves.

Download Full-text