Unusually large ephedrine-induced blood pressure increases due to cardiac sympathetic denervation supersensitivity in a patient with Parkinson's disease

Functional and 123I-MIBG scintigraphy assessment of cardiac adrenergic dysfunction in diabetes

OBJECTIVES

To assess the agreement between clinical cardiovascular adrenergic function and cardiac adrenergic innervation in type 2 diabetes patients (T2D).

METHODS

Thirty-three patients with T2D were investigated bimodally through (1) a standardized clinical cardiovascular adrenergic assessment, evaluating adequacy of blood pressure responses to the Valsalva maneuver and (2) 123I-meta-iodobenzylguanidine (MIBG) scintigraphy assessing myocardial adrenergic innervation measured as early and delayed heart heart/mediastinum (H/M) ratio, and washout rate (WR).

RESULTS

T2D patients had significantly lower early and delayed H/M-ratios, and lower WR, compared to laboratory specific reference values. Thirteen patients had an abnormal adrenergic composite autonomic severity score (CASS > 0). Patients with abnormal CASS scores had significantly higher early H/M ratios (1.76 [1.66-1.88] vs. 1.57 [1.49-1.63], p < 0.001), higher delayed H/M ratios (1.64 [1.51:1.73] vs. 1.51 [1.40:1.61] (p = 0.02)), and lower WR (-0.13(0.10) vs -0.05(0.07), p = 0.01). Lower Total Recovery and shorter Pressure Recovery Time responses from the Valsalva maneuver was significantly correlated to lower H/M early (r = 0.55, p = 0.001 and r = 0.5, p = 0.003, respectively) and lower WR for Total Recovery (r = -0.44, p = 0.01).

CONCLUSION

The present study found impairment of sympathetic innervation in T2D patients based on parameters derived from MIBG cardiac scintigraphy (low early H/M, delayed H/M, and WR). These results confirm prior studies. We found a mechanistically inverted relationship with favourable adrenergic cardiovascular responses being significantly associated unfavourable MIBG indices for H/M early and delayed. This paradoxical relationship needs to be further explored but could indicate adrenergic hypersensitivity in cardiac sympathetic denervated T2D patients.

Severe blood pressure elevation following ephedrine administration during carotid endarterectomy under general anesthesia: A CARE-compliant case report

RATIONALE

During carotid endarterectomy (CEA) surgery, blood pressure management is particularly important to prevent cerebrovascular and cardiac complications. Ephedrine is a commonly used vasopressor, however, we report the case of a patient with unusually severe blood pressure elevation following intravenous ephedrine administration during CEA.

PATIENT CONCERNS

A 72-year-old man diagnosed with right proximal internal carotid artery stenosis underwent CEA under general anesthesia. After declamping the common carotid artery, blood pressure rapidly increased by 125 mm Hg (from 90 to 215 mm Hg) after ephedrine (4 mg) was administered, but the heart rate was stable.

DIAGNOSES

There was an ordinal increase in blood pressure after the same small dose of ephedrine was administered at the early stage of the surgery. And the surgical approach was difficult because he had a high location of carotid bifurcation and a prominent mandibular angle. Because of the anatomical proximity of the cervical sympathetic trunk to the carotid bifurcation and the particularly complicated surgical process in the present case, we postulate the reason for this adverse reaction as transient sympathetic denervation supersensitivity.

INTERVENTIONS

Perdipine (0.5 mg) was administered repeatedly to reduce blood pressure.

OUTCOMES

After surgery, he was diagnosed with right hypoglossal nerve palsy, and no other abnormal signs were found.

CONCLUSION

This case highlights the need for caution in the use of ephedrine, which is commonly used in CEA surgery, wherein blood pressure management is particularly important. Although it is a rare and unpredictable case, α-agonists are considered safer in situations where sympathetic supersensitivity is possible.

Adrenergic supersensitivity and impaired neural control of cardiac electrophysiology following regional cardiac sympathetic nerve loss

Myocardial infarction (MI) can result in sympathetic nerve loss in the infarct region. However, the contribution of hypo-innervation to electrophysiological remodeling, independent from MI-induced ischemia and fibrosis, has not been comprehensively investigated. We present a novel mouse model of regional cardiac sympathetic hypo-innervation utilizing a targeted-toxin (dopamine beta-hydroxylase antibody conjugated to saporin, DBH-Sap), and measure resulting electrophysiological and Ca²⁺ handling dynamics. Five days post-surgery, sympathetic nerve density was reduced in the anterior left ventricular epicardium of DBH-Sap hearts compared to control. In Langendorff-perfused hearts, there were no differences in mean action potential duration (APD₈₀) between groups; however, isoproterenol (ISO) significantly shortened APD₈₀ in DBH-Sap but not control hearts, resulting in a significant increase in APD₈₀ dispersion in the DBH-Sap group. ISO also produced spontaneous diastolic Ca²⁺ elevation in DBH-Sap but not control hearts. In innervated hearts, sympathetic nerve stimulation (SNS) increased heart rate to a lesser degree in DBH-Sap hearts compared to control. Additionally, SNS produced APD₈₀ prolongation in the apex of control but not DBH-Sap hearts. These results suggest that hypo-innervated hearts have regional super-sensitivity to circulating adrenergic stimulation (ISO), while having blunted responses to SNS, providing important insight into the mechanisms of arrhythmogenesis following sympathetic nerve loss.