Direct Vasodilators and Sympatholytic Agents

First, a seat; then, an upgrade

The Sir Stanley Peart Essay Competition is an annual event run by the British and Irish Hypertension Society to encourage Early Career Researchers to continue the ethos of Sir Stanley Peart. Sir Stanley Peart was a clinician and clinical researcher who made a major contribution to our understanding of blood pressure regulation. He was the first to demonstrate the release of noradrenaline in response to sympathetic nerve stimulation. He was also the first to purify, and determine the structure of, angiotensin and he later isolated the enzyme, renin, and carried out many important investigations of the factors controlling its release in the body. This year, the essay topic was "Do we need new classes of antihypertensive drugs?". In his prize-winning essay, "First, a seat; then, an upgrade", Dr Sathyanarayanan argues that we do not need new classes of antihypertensive drugs, instead we should focus our attention on addressing the factors that lead to high blood pressure in the first place and use our existing drug classes more effectively.

Blood Pressure Management in Intracerebral Haemorrhage: when, how much, and for how long?

PURPOSE OF REVIEW

When compared to ischaemic stroke, there have been limited advances in acute management of intracerebral haemorrhage. Blood pressure control in the acute period is an intervention commonly implemented and recommended in guidelines, as elevated systolic blood pressure is common and associated with haematoma expansion, poor functional outcomes, and mortality. This review addresses the uncertainty around the optimal blood pressure intervention, specifically timing and length of intervention, intensity of blood pressure reduction and agent used.

RECENT FINDINGS

Recent pivotal trials have shown that acute blood pressure intervention, to a systolic target of 140mmHg, does appear to be beneficial in ICH, particularly when bundled with other therapies such as neurosurgery in selected cases, access to critical care units, blood glucose control, temperature management and reversal of coagulopathy. Systolic blood pressure should be lowered acutely in intracerebral haemorrhage to a target of approximately 140mmHg, and that this intervention is generally safe in the ICH population.

The Global Burden of Resistant Hypertension and Potential Treatment Options

Resistant hypertension (RH) is defined as systolic blood pressure (SBP) or diastolic blood pressure (DBP) that remains .140 mmHg or .90 mmHg, respectively, despite an appropriate lifestyle and the use of optimal or maximally tolerated doses of a three-drug combination, including a diuretic. This definition encompasses the category of controlled RH, defined as the presence of blood pressure (BP) effectively controlled by four or more antihypertensive agents, as well as refractory hypertension, referred to as uncontrolled BP despite five or more drugs of different classes, including a diuretic. To confirm RH presence, various causes of pseudo-resistant hypertension (such as improper BP measurement techniques and poor medication adherence) and secondary hypertension must be ruled out. Inadequate BP control should be confirmed by out-of-office BP measurement. RH affects about 5% of the hypertensive population and is associated with increased cardiovascular morbidity and mortality. Once RH presence is confirmed, patient evaluation includes identification of contributing factors such as lifestyle issues or interfering drugs/substances and assessment of hypertension-mediated organ damage. Management of RH comprises lifestyle interventions and optimisation of current medication therapy. Additional drugs should be introduced sequentially if BP remains uncontrolled and renal denervation can be considered as an additional treatment option. However, achieving optimal BP control remains challenging in this setting. This review aims to provide an overview of RH, including its epidemiology, pathophysiology, diagnostic work-up, as well as the latest therapeutic developments.

Methodological challenges in using human umbilical artery as a model for in vitro studies

NEW FINDINGS

What is the central question of this study? What are the biggest challenges in performing in vitro studies on isolated human umbilical arteries? What is the main finding and its importance? The protocols presented in this study indicate some potential outcomes important for interpretation of the vascular responsivities of human umbilical arteries and could be useful for planning future in vitro studies with human umbilical arteries.

ABSTRACT

Human umbilical artery (HUA) preparations are of particular importance for in vitro studies on isolated blood vessels because their sampling is not risky for the patient, and they can provide the closest possible impression of changes related to the uteroplacental circulation during pre-eclampsia. Using organ bath techniques, useful experimental protocols are provided for measuring some pathophysiological phenomena in the vascular responses of HUAs. Several vasoconstrictors (serotonin, prostaglandin F and phenylephrine) and vasodilators (acetylcholine and minoxidil) were seleted for determination of their vasoactivity in HUAs. The role of L-type voltage-operated calcium channels and different types of potassium channels (KATP , BKCa and KV ) were assessed, as was the impact of homocysteine. Serotonin was confirmed to be the most potent vasoconstrictor, while acetylcholine and phenylephrine caused variability in the relaxation and contraction response of HUA, respectively. The observed increase in serotonin-induced contraction and a decrease in minoxidil-induced relaxation in the presence of homocysteine suggested its procontractile effect on HUA preparations. Using selective blockers, it was determined that KATP and KV channels participate in the minoxidil-induced relaxation, while L-type voltage-dependent Ca2+  channels play an important role in the serotonin-induced contraction. The presented protocols reveal some of the methodological challenges related to HUA preparations and indicate potential outcomes in interpreting the vascular effects of the investigated substances, both in physiological conditions and in the homocysteine-induced pre-eclampsia model.

A Rare Case of Hydralazine-Induced Diffuse Alveolar Hemorrhage

Hydralazine-induced anti-neutrophil cytoplasmic antibody (ANCA) vasculitis may occur any time after hydralazine initiation. General internists should recognize diffuse alveolar hemorrhage (DAH) as a rare complication of this condition, as early treatment reduces the associated high risk of mortality. We describe the case of an 82-year-old female with diastolic heart failure who presented with a one-month history of worsening dyspnea on exertion and a one-week history of scant hemoptysis and fatigue. Her medications included aspirin and hydralazine. She was hypoxic with bilateral expiratory wheezes on exam. Labs showed new anemia, elevated creatinine, proteinuria, and hematuria. Chest computed tomography showed asymmetric bilateral upper lobe ground-glass attenuation superimposed on interlobular septal thickening and intralobular lines. Further testing showed anti-nuclear antibody, positive ANCA, perinuclear ANCA (p-ANCA), and anti-myeloperoxidase ANCA (anti-MPO-ANCA). Renal biopsy revealed MPO-ANCA, pauci-immune, necrotizing, and crescentic glomerulonephritis. She was diagnosed with DAH secondary to hydralazine-induced ANCA-associated vasculitis (AAV). Hydralazine is an anti-hypertensive medication with known potential for autoimmune reactions. Of these, AAV is a rare sequela mediated by anti-MPO and most commonly affects the kidneys. In rare circumstances, patients with AAV can develop pulmonary-renal syndrome, resulting in both glomerulonephritis and DAH with an associated high risk of mortality. Diagnosis requires a high index of suspicion in patients with acute kidney injury of unclear etiology. Early diagnosis through immune work-up and kidney biopsy should be pursued, as prompt recognition of the vasculitis, cessation of hydralazine, immunosuppression, and early plasma exchange are essential to an improved prognosis.

Revisiting resistant hypertension: a comprehensive review

Resistant hypertension (RHT) is typically defined as blood pressure that remains above guideline-directed targets despite the use of three anti-hypertensives, usually including a diuretic, at optimal or maximally tolerated doses. It is generally estimated to affect 10-30% of those diagnosed with hypertension, though the true incidence might be lower after one factor in the prevalence of non-adherence. Risk factors for its development include diabetes, obesity and other adverse lifestyle factors, and a diagnosis of RHT confers a greater risk of adverse cardiovascular outcomes, such as stroke, heart failure and mortality. It is essential to exclude pseudoresistance and secondary hypertension and to ensure non-pharmacologic management is optimised prior to consideration of fourth-line anti-hypertensive agents or advanced interventions, such as device therapies. In this review, we will cover the different definitions of RHT, along with the importance of careful diagnosis and management strategies, and discuss newer agents and research needs.

Hydralazine-Induced Anti-neutrophil Cytoplasmic Antibody (ANCA)-Associated Vasculitis

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis comprises several conditions involving vascular destruction that extends into tissue necrosis. There are several autoimmune and environmental causes implicated in the disease progression; among these is drug-induced vasculitis caused by hydralazine use. Hydralazine-induced vasculitis is an uncommon potential complication of the medication and can progress to multisystem involvement and eventually advance to end-organ damage and renal failure. Our patient presented with symptoms of lower extremity edema, dyspnea, and a nonproductive cough eventually resulting in the identification of hydralazine-induced ANCA-associated vasculitis with hypocomplementemia and positive anti-histone antibody. Due to the prevalence of hydralazine as a cardiac drug, physicians managing patients on the medication should have a high index of suspicion of the potential for vasculitis in order to promote prompt diagnosis and treatment of the ANCA-vasculitis.

Microneedles and Their Application in Transdermal Delivery of Antihypertensive Drugs-A Review

One of the most cutting-edge, effective, and least invasive pharmaceutical innovations is the utilization of microneedles (MNs) for drug delivery, patient monitoring, diagnostics, medicine or vaccine delivery, and other medical procedures (e.g., intradermal vaccination, allergy testing, dermatology, and blood sampling). The MN-based system offers many advantages, such as minimal cost, high medical effectiveness, comparatively good safety, and painless drug application. Drug delivery through MNs can possibly be viewed as a viable instrument for various macromolecules (e.g., proteins, peptides, and nucleic acids) that are not efficiently administered through traditional approaches. This review article provides an overview of MN-based research in the transdermal delivery of hypertensive drugs. The critical attributes of microneedles are discussed, including the mechanism of drug release, pharmacokinetics, fabrication techniques, therapeutic applications, and upcoming challenges. Furthermore, the therapeutic perspective and improved bioavailability of hypertensive drugs that are poorly aqueous-soluble are also discussed. This focused review provides an overview of reported studies and the recent progress of MN-based delivery of hypertensive drugs, paving the way for future pharmaceutical uses. As MN-based drug administration bypasses first-pass metabolism and the high variability in drug plasma levels, it has grown significantly more important for systemic therapy. In conclusion, MN-based drug delivery of hypertensive drugs for increasing bioavailability and patient compliance could support a new trend of hypertensive drug delivery and provide an alternative option, overcoming the restrictions of the current dosage forms.

Increased plasma renin by vasodilators promotes the progression of abdominal aortic aneurysm

Background: It is well-accepted that antihypertensive therapy is the cornerstone of treatment for abdominal aortic aneurysm (AAA) patients with hypertension. Direct-acting vasodilators were used in the treatment of hypertension by directly relaxing vascular smooth muscle but may have destructive effects on the aortic wall by activating the renin-angiotensin system axis. Their roles in AAA disease remain to be elucidated. In this study, we used hydralazine and minoxidil, two classical direct-acting vasodilators, to investigate their influence and potential mechanisms on AAA disease. Methods and results: In this study, we investigated the plasma renin level and plasma renin activity in AAA patients. Simultaneously, age and gender ratio-matched patients diagnosed with peripheral artery disease and varicose veins were selected as the control group using a ratio of 1:1:1. Our regression analysis suggested both the plasma renin level and plasma renin activity are positively associated with AAA development. In view of the well-established relationship between direct-acting vasodilators and increased plasma renin concentration, we established a porcine pancreatic elastase-infused AAA mouse model, followed by oral administration of hydralazine (250 mg/L) and minoxidil (120 mg/L) to investigate effects of direct-acting vasodilators on AAA disease. Our results suggested both hydralazine and minoxidil promoted the progression of AAA with increased aortic degeneration. Mechanistically, the vasodilators aggravated aortic inflammation by increased leukocyte infiltration and inflammatory cytokine secretion. Conclusion and relevance: The plasma renin level and plasma renin activity are positively associated with AAA development. Direct vasodilators aggravated experimental AAA progression, which raised cautionary concerns about their applications in AAA disease.

Novel wine in an old bottle: Preventive and therapeutic potentials of andrographolide in atherosclerotic cardiovascular diseases

Atherosclerotic cardiovascular disease (ASCVD) frequently results in sudden death and poses a serious threat to public health worldwide. The drugs approved for the prevention and treatment of ASCVD are usually used in combination but are inefficient owing to their side effects and single therapeutic targets. Therefore, the use of natural products in developing drugs for the prevention and treatment of ASCVD has received great scholarly attention. Andrographolide (AG) is a diterpenoid lactone compound extracted from Andrographis paniculata. In addition to its use in conditions such as sore throat, AG can be used to prevent and treat ASCVD. It is different from drugs that are commonly used in the prevention and treatment of ASCVD and can not only treat obesity, diabetes, hyperlipidaemia and ASCVD but also inhibit the pathological process of atherosclerosis (AS) including lipid accumulation, inflammation, oxidative stress and cellular abnormalities by regulating various targets and pathways. However, the pharmacological mechanisms of AG underlying the prevention and treatment of ASCVD have not been corroborated, which may hinder its clinical development and application. Therefore, this review summarizes the physiological and pathological mechanisms underlying the development of ASCVD and the in vivo and in vitro pharmacological effects of AG on the relative risk factors of AS and ASCVD. The findings support the use of the old pharmacological compound ('old bottle') as a novel drug ('novel wine') for the prevention and treatment of ASCVD. Additionally, this review summarizes studies on the availability as well as pharmaceutical and pharmacokinetic properties of AG, aiming to provide more information regarding the clinical application and further research and development of AG.

The Effects of Verapamil, Hydralazine, and Doxazosin on Renin, Aldosterone, and the Ratio Thereof

PURPOSE

Hydralazine, doxazosin, and verapamil are currently recommended by the Endocrine Society as acceptable bridging treatment in those in whom full cessation of antihypertensive medication is infeasible during screening for primary aldosteronism (PA). This is under the assumption that they cause minimal to no effect on the aldosterone-to-renin ratio, the most widely used screening test for PA. However, limited evidence is available regarding the effects of these particular drugs on said ratio.

METHODS

In the present study, we retrospectively assessed the changes in aldosterone, renin, and aldosterone-to-renin values in essential hypertensive participants before and after treatment with either hydralazine (n = 26) or doxazosin (n = 20) or verapamil (n = 15). All samples were taken under highly standardized conditions.

RESULTS

Hydralazine resulted in a borderline significant rise in active plasma renin concentration (19 vs 25 mIU/L, p = 0.067) and a significant fall in the aldosterone-to-renin ratio (38 vs 24, p = 0.017). Doxazosin caused declines in both plasma aldosterone concentration (470 vs 330 pmol/L, p = 0.028) and the aldosterone-to-renin ratio (30 vs 20, p = 0.020). With respect to verapamil, we found no statistically significant effect on any of these outcome variables.

CONCLUSION

We conclude that the assumption that these drugs can be used with little consequence to the aldosterone-to-renin cannot be substantiated. While it is possible that they are indeed the best option when full antihypertensive drug cessation is infeasible, the potential effects of these drugs must still be taken into account when interpreting the aldosterone-to-renin ratio.

Malate reduced blood pressure and exerted differential effects on renal hemodynamics; role of the nitric oxide system and renal epithelial sodium channels (ENaC)

Malate regulates blood pressure via nitric oxide production in salt-sensitive rats, a genetic model of hypertension. This study investigated the possible contributions of malate to blood pressure regulation and renal haemodynamics in normotensive rats. Malate (0.1, 0.3 and 1 μg/kg, iv) was injected into rats or L-nitro-arginine methyl ester (L-NAME)-treated rats and mean arterial blood pressure (MABP), cortical blood flow (CBF), and medullary blood flow (MBF), was measured. The clearance study involved infusion of malate at 0.1 μg/kg/h into rats, and MABP, CBF, MBF, glomerular filtration rate (GFR), urine volume (UV) and sodium output (UNaV) were determined. Mechanistic studies to evaluate the role of renal sodium channels involved the treatment with malate (600 mg/kg, po), amiloride (2.5 mg/kg, po) or hydrochlorothiazide (HCTZ) (10 mg/kg, po), and UV and UNaV were determined. Malate elicited significant peak reductions in MABP (124 ± 6.5 vs 105 ± 3.1 mmHg) at 0.1 μg/kg), CBF (231 ± 18.5 vs 205 ± 10.9 PU). L-NAME did not reverse the effect of malate on MABP but tended to blunt the effect on CBF (40%) and MBF (87%) at 0.3 μg/kg. Infusion of malate reduced MABP, CBF, and MBF in a time-dependent manner (p<0.05). Malate exerted a three-fold decrease in GFR in a time-related fashion (p<0.05) as well as increased UV. UNaV increased by 86% in malate-treated-amiloride rats (p<0.05). These data indicate that malate modulates blood pressure and exerts vascular and tubular effects on renal function that may involve epithelial sodium channels (ENaC).

A review on the clinical pharmacokinetics of hydralazine

INTRODUCTION

Hydralazine is a vasodilator used to treat hypertension, pre-eclampsia, and heart failure. The current article reviews the clinical pharmacokinetics (PK) of hydralazine, which can be useful for clinicians in optimizing its dose and dosing frequency to avoid adverse effects and unexpected interactions that could risk patients' lives.

AREAS COVERED

This review has summarized the PK parameters for hydralazine after performing an extensive literature search. It includes 20 publications that were selected after applying eligibility criteria out of a pool of literature that was searched using Google Scholar, PubMed, Cochrane Central, and EBSCO databases. The included studies consisted of concentration vs. time profiles of hydralazine. If the PK data were not tabulated in the given study, the concentration vs. time profiles were scanned for the extraction of the PK data. The PK parameters were calculated by applying a non-compartmental analysis (NCA).

EXPERT OPINION

The current review will aid clinicians in understanding hydralazine PK in different disease populations. This clinical PK data might also be helpful in the development of a pharmacokinetic model of hydralazine.

Is tadalafil associated with decreased risk of major adverse cardiac events or venous thromboembolism in men with lower urinary tract symptoms?

Purpose

To evaluate the association of tadalafil, a phosphodiesterase-5 inhibitor (PDE5I), with major adverse cardiac events (MACE) or venous thromboembolism (VTE) in men with lower urinary tract symptoms (LUTS).

Methods

Data was obtained from the TriNetX Research Network, ICD-10 codes were used to identify men with LUTS, MACE, and VTE. In addition, demographic characteristics and use of tadalafil or alpha-blocker was evaluated. Then, unbalanced and balanced association analyses was performed to assess the relation between tadalafil and/or alpha-blocker use with MACE/VTE.

Results

After participant selection, analysis included 821,592 men that did not use an alpha blocker or tadalafil, 5,004 men that used tadalafil but no alpha blocker, 327,482 men that used an alpha blocker but no tadalafil, and 6,603 men that used both an alpha blocker and tadalafil. On balanced analysis, tadalafil was independently associated with a decreased risk of MACE/VTE within a 3-year time period (OR = 0.59, 95%CI 0.49–0.70, p < 0.0001). Among men with a history of alpha blocker use, tadalafil use was also independently associated with a decreased risk of MACE or VTE, both before and after controlling for potentially confounding variables (OR = 0.57, 95%CI: 0.50–0.66; p < 0.0001).

Conclusions

In our study, tadalafil was associated with a decreased risk of MACE/VTE in men with LUTS with and without a history of alpha blocker use. It is time to perform further long-term prospective randomized studies to further analyze the cardiovascular effects of PDE5Is as combination treatment with alpha blockers in the management of LUTS.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00345-022-04005-3.

Phenotype-Directed Management of Hypertension in Pregnancy

Hypertensive disorders of pregnancy are among the most serious conditions that pregnancy care providers face; however, little attention has been paid to the concept of tailoring clinical care to reduce associated adverse maternal and perinatal outcomes based on the underlying disease pathogenesis. This narrative review discusses the integration of phenotype-based clinical strategies in the management of high-risk pregnant patients that are currently not common clinical practice: real-time placental growth factor testing at Mount Sinai Hospital, Toronto and noninvasive hemodynamic monitoring to guide antihypertensive therapy at the University of Washington Medical Center, Seattle. Future work should focus on promoting more widespread integration of these novel strategies into obstetric care to improve outcomes of pregnancies at high risk of adverse maternal-fetal outcomes from these complications of pregnancy.

Flavonoids extract from the seeds of Psoralea corylifolia L. (PFE) alleviates atherosclerosis in high-fat diet-induced LDLR-/- mice

BACKGROUND

The seeds of Psoralea corylifolia L., a traditional medicine popular used in China and India, have been recommended in the treatment of leucoderma, psoriasis, osteoporosis, and gynecological bleeding. Our previous studies have found that flavonoid extract from the seeds of Psoralea corylifolia L. could activate fat browning and correct the disorder of glucose and lipid metabolism in obese mice.

PURPOSE

The present study aimed to investigate the anti-atherosclerosis of flavonoids extract from the seeds of Psoralea corylifolia L.

METHODS

Leukocyte adhesion assay, RT-PCR, Western blot analysis, and immunofluorescent assay were carried out in ox-LDL induced endothelium injury and foam cells formation in vitro. Flavonoids from the seeds of P. corylifolia L. (PFE) was administrated 150 and 300 mg/kg/day in HFD-induced LDLR-/- mice for 12 weeks.

RESULTS

Flavonoids from the seeds of P. corylifolia L. (PFE) could prevent leukocyte adhesion to the endothelium by inhibiting mRNA and protein expression of these adhesion molecules (VCAM-1, ICAM-1, and E-selectin). PFE could also prevent ox-LDL stimulated inflammation in HUVECs by inhibiting the NF-κB pathway. In addition, PFE significantly ameliorated ox-LDL induced macrophages-oriented foam cells formation through inducing cholesterol efflux via PPARγ-ABCA1/ABCG1. In HFD-induced LDLR-/- mice, PFE reversed the serum profile and circulated inflammation level. Meanwhile, PFE could remarkably alleviate atherosclerotic lesion sizes and intraplaque macrophage infiltration in aortic roots.

CONCLUSION

Flavonoids from the seeds of P. corylifolia L. could alleviate atherosclerosis by preventing endothelium injury, attenuating vascular inflammation, and alleviating the formation of foam cells.

Antihypertensive effects of allicin on spontaneously hypertensive rats via vasorelaxation and hydrogen sulfide mechanisms

BACKGROUND

Allicin, the principle active constituent in garlic, has been reported to have antihypertensive effects on drug-induced hypertension or renal hypertension in rats, but reports on spontaneously hypertensive rats (SHRs) are rare. Allicin is comprised of a variety of sulfur-containing compounds, and hydrogen sulfide (H₂S) has been shown to have specific vasomotor effects. We therefore hypothesize that allicin may exert a vasorelaxant activity by inducing H₂S production, and this eventually result in a reduction in blood pressure in SHRs.

METHODS

The in vivo antihypertensive effect of allicin was assessed using a tail-cuff method on SHRs. The in vitro vasorelaxant effect and in-depth mechanisms of allicin were explored on rat mesenteric arterial rings (RMARs) isolated from SD rats.

RESULTS

In the in vivo study, administration of allicin (7 mg/kg and 14 mg/kg, 4 weeks, i.g) dramatically decreased the blood pressure in SHRs, which was also shown to be attenuated by H₂S synthase inhibitor (PAG, 32 mg/kg, i.g). In in vitro studies, allicin (2.50-15.77 mM) produced a concentration-dependent vasorelaxation on RMARs, which was obviously reduced by preincubation with PAG. The removal of endothelium led to a decline in allicin's vasorelaxation, which was almost completely mitigated when treatment was followed with PAG. Inhibitors of nitric oxide (NO) and prostaglandin (PGI₂) pathways separately suppressed the vasorelaxation induced by allicin to a certain degree. When the RMARs incubated with PAG were treated with or without the above inhibitors in separate groups, the relaxations caused by allicin were almost identical under both these conditions. Moreover, allicin treatment increased cyclic guanosine monophosphate (cGMP) and cyclic adenosine monophosphate (cAMP) levels (downstream products of NO and PGI₂ pathways), which was decreased by PAG. Additionally, allicin increased the acetylcholine-induced endothelium-derived hyperpolarizing factor (EDHF) -mediated relaxation, which was unaffected by PAG.

CONCLUSION

Allicin exhibits a potent antihypertensive effect through vasodilatory properties and H₂S mechanisms. Moreover, the vasodilation of allicin is partially dependent on endothelium. The endothelium-dependent vasodilation of allicin is mediated by the NO-sGC-cGMP, PGI₂-AC-cAMP and EDHF pathways, of which H₂S participates in the first two but not the third one. The endothelium independent vasodilation can be predominantly attributed to H₂S production.

Management of resistant hypertension

PURPOSE OF REVIEW

Resistant hypertension is defined as blood pressure above patient goal despite three different antihypertensive agents at optimal dose including a diuretic. Resistant hypertension is increasingly common issue in clinical practice and it is a major risk factor of cardiovascular disease.

RECENT FINDINGS

All patients with resistant hypertension should be evaluated for possible correctable factors associated with pseudoresistance, such as poor adherence, white coat hypertension and suboptimal measurement of blood pressure. In patients with resistant hypertension, thiazide diuretics should be considered as one of the first agents, in addition to mineralocorticoids receptor antagonist.

SUMMARY

Resistant hypertension can be associated with secondary cause that is why treatment can be challenging and should always include lifestyle modification and evaluation for possible secondary causes, in addition to adding a fourth agent or considering newer interventional therapies, such as renal denervation or other device-based options.

The flipside of hydralazine in pregnancy: A systematic review and meta-analysis

The present systematic review and meta-analysis investigated the effects of hydralazine compared with other antihypertensive drugs in maternal, perinatal and neonatal outcomes of pregnant women with hypertensive disorders. Twenty studies with 1283 participants were included. Of them, 626 received hydralazine and 657 other antihypertensive treatments, such as labetalol, nifedipine, ketanserin, diazoxide, urapidil, isradipine and epoprostenol. Women receiving hydralazine had higher heart rate (WMD: 13.4, 95%CI: 0.1 to 26.8 beats/min), increased number of adverse effects (RR: 1.21, 95%CI: 1.01 to 1.45) and gave birth to neonates of lower birthweight (WMD: 13.4, 95%CI: 0.1 to 26.8 beats/min) compared with other antihypertensive treatments at the end of follow-up. When studies, which used antihypertensive agents that are no longer indicated for hypertension in pregnancy, were excluded in the sensitivity analyses, hydralazine found not to have a statistically significant difference compared with labetalol and nifedipine regarding the reduction of maternal blood pressure (WMD: 1.72, 95%CI: -1.47 to 4.9 mmHg for systolic, WMD: 0.26, 95%CI: -1.75 to 2.28 mmHg for diastolic), maternal heart rate (WMD: 13.56, 95%CI: -5.62 to 32.74 beats/min), low birthweight (WMD: -88.62, 95%CI: -243.24 to 66 beats/min) and adverse events (RR: 1.19, 95%CI: 0.99 to 1.43). Hydralazine seems not to be inferior compared to labetalol and nifedipine for safety and efficacy.

Alpha-1 Adrenergic-Antagonist Use Increases the Risk of Sleep Apnea: A Nationwide Population-Based Cohort Study

STUDY OBJECTIVES

Decreased upper-airway muscle responsiveness is one of the major phenotypes of obstructive sleep apnea. Use of α1-adrenergic antagonists is correlated with decreased muscle responsiveness in animal studies, but this association has not yet been demonstrated in humans. This study examined whether use of α1-adrenergic antagonists is an independent risk factor for sleep apnea in humans.

METHODS

Data for this retrospective cohort study were obtained from the National Health Insurance Research Database from Taiwan. Between 2000 and 2012, 25,466 patients with hypertension and 18,930 patients without hypertension were enrolled. These groups were divided into α1-adrenergic antagonist users and nonusers, matched by age, sex, and index year. Individuals were monitored for diagnosis of sleep apnea until 2013.

RESULTS

After adjusting for propensity score and potential confounders, including age, geographic location, enrollee category, income, urbanization level, comorbidities, and medication, the adjusted hazard ratios (HRs) for development of sleep apnea with α1-adrenergic antagonist use were 2.38 (95% confidence interval [CI] 1.82-3.10) and 2.82 (95% CI 1.79-4.44) in the hypertension and nonhypertension groups, respectively. Similarly, the adjusted HRs for development of severe sleep apnea with α1-adrenergic antagonist use were 2.74 (95% CI 1.78-4.22) and 4.23 (95% CI 1.57-11.40) in hypertension and nonhypertension patient groups, respectively. The interaction between α1-adrenergic-antagonist user and patients with hypertension was tested using multivariable Cox regression. The results showed that there are positive additive interactions for developing sleep apnea and severe sleep apnea, respectively.

CONCLUSIONS

Our study suggests that patients with hypertension using α1-adrenergic antagonists have a higher risk of sleep apnea. Routine sleep apnea screening would be beneficial for patients with hypertension who take α1-adrenergic antagonists.

Perivascular adipose tissue and the dynamic regulation of Kv 7 and Kir channels: Implications for resistant hypertension

Resistant hypertension is defined as high blood pressure that remains uncontrolled despite treatment with at least three antihypertensive drugs at adequate doses. Resistant hypertension is an increasingly common clinical problem in older age, obesity, diabetes, sleep apnea, and chronic kidney disease. Although the direct vasodilator minoxidil was introduced in the early 1970s, only recently has this drug been shown to be particularly effective in a subgroup of patients with treatment-resistant or uncontrolled hypertension. This pharmacological approach is interesting from a mechanistic perspective as minoxidil is the only clinically used K⁺ channel opener today, which targets a subclass of K⁺ channels, namely K_ATP channels in VSMCs. Beside K_ATP channels, two other classes of VSMC K⁺ channels could represent novel effective targets for treatment of resistant hypertension, namely K_v 7 (KCNQ) and inward rectifier potassium (K_ir 2.1) channels. Interestingly, these channels are unique among VSMC potassium channels. First, both have been implicated in the control of microvascular tone by perivascular adipose tissue. Second, they exhibit biophysical properties strongly controlled and regulated by membrane voltage, but not intracellular calcium. This review focuses on K_v 7 (K_v 7.1-5) and K_ir (K_ir 2.1) channels in VSMCs as potential novel drug targets for treatment of resistant hypertension, particularly in comorbid conditions such as obesity and metabolic syndrome.

Anesthetic Treatment of Cardiac Disease During Pregnancy

PURPOSE OF REVIEW

This review summarizes the pathophysiology, peripartum treatment, and anesthetic management of parturients with cardiac disease. Valvular disease, coronary disease, and cardiomyopathy are specifically addressed in the context of the normal physiologic changes of pregnancy. We offer recommendations for anesthetic approaches, hemodynamic goals with an emphasis on interdisciplinary planning between anesthesiologists, cardiologists, cardiothoracic surgeons, obstetricians, maternal fetal medicine specialists, and neonatologists.

RECENT FINDINGS

Vaginal delivery with neuraxial analgesia can be well tolerated by many pregnant patients with cardiac disease when coordinated by an interdisciplinary team of experts. Cardiac disease in pregnancy can present a significant challenge for the interdisciplinary care team. A detailed understanding of each patient's cardiac pathology and the physiologic changes of pregnancy are critical to ensure a safe and successful labor and delivery. Optimized medical therapy in the peripartum period and neuraxial anesthesia with the judicious use of vasoactive agents can be of great benefit for these parturients. As is generally the case, cesarean delivery should be primarily reserved for obstetric indications and maternal wellbeing, with careful consideration of the fetus to guide best practices.

A case report of clonidine induced syncope: a review of central actions of an old cardiovascular drug

Background

Clonidine is an imidazoline sympatholytic, acting on both α₂-adrenergic and imidazoline receptors in the brainstem to induce antihypertensive and negative chronotropic effects in the vasculature and heart respectively.

Case presentation

A 69-year-old gentleman with hypertension presented to the emergency department after multiple syncopal episodes over the past 12 months. Electrocardiogram demonstrated sinus bradycardia with a heart rate of 42 beats per minute. It was hypothesized that the antihypertensive agent clonidine was responsible for inducing symptomatic bradycardia. Clonidine was thus gradually tapered and then discontinued over five days restoring normal sinus rhythm rates while avoiding hypertensive rebound related to sympathetic surge. His heart rate and blood pressure remained within normal limits after the clonidine taper and subsequent adjustments to his other hypertensive medications and he was discharged.

Conclusions

While clonidine has fallen out of favor for its indication as an antihypertensive, it remains a viable option for the use of opioid withdrawal, chronic pain, and smoking cessation, necessitating the appropriate clinical and pharmacological competencies for a physician to prescribe. A discussion of the clinical effects of clonidine brainstem receptor activation follows.

Neurohormonal Blockade in Heart Failure

A key feature of chronic heart failure (HF) is the sustained activation of endogenous neurohormonal systems in response to impaired cardiac pumping and/or filling properties. The clinical use of neurohormonal blockers has revolutionised the care of HF patients over the past three decades. Drug therapy that is active against imbalance in both the autonomic and renin-angiotensin-aldosterone systems consistently reduces morbidity and mortality in chronic HF with reduced left ventricular ejection fraction and in sinus rhythm. This article provides an assessment of the major neurohormonal systems and their therapeutic blockade in patients with chronic HF.

Cardiovascular/Pulmonary Medications and Male Reproduction

Cardiovascular and respiratory medications are used by men of reproductive age although use of the former is most prevalent in advanced age. Many of these drugs have been associated with sexual dysfunction, including erectile and ejaculatory dysfunction, but for most there is insufficient evidence to link their use with testicular dysfunction, reduced semen quality or infertility. Some exceptions are the irreversible α₁-adrenergic antagonist phenoxybenzamine, which carries a high risk of retrograde ejaculation; the specific α_1A-adrenergic antagonists silodosin and tamsulosin, used primarily to treat BPH/lower urinary tract symptoms, which can cause retrograde ejaculation; and the peripheral β₁-adrenergic antagonist atenolol, used to treat hypertension, which may decrease testosterone/free-testosterone levels. In this chapter, we review the evidence available regarding adverse reactions on male reproduction of adrenergic receptor agonists/antagonists, calcium channel blockers, angiotensin converting enzyme (ACE) inhibitors, diuretics, digoxin, and hydralazine. For some of these medications, there is some evidence for male reproductive effects, along with some solid work in experimental and companion animal species suggesting negative effects. In contrast, and of special note, are calcium channel blockers, which have long been included on lists of medications with the potential to cause male infertility. This turns out to be a good example of a substance with profound effects on sperm function in vitro, but with limited evidence for in vivo effects on semen quality or fertility, even in experimental species. We hope that the evidence provided in this chapter will stimulate additional studies for these important classes of medications.

Minoxidil for Treatment of Resistant Hypertension in Chronic Kidney Disease--A Retrospective Cohort Analysis

Resistant hypertension is still a challenge and reserve antihypertensive agents are often necessary to achieve blood pressure control. One reserve antihypertensive is minoxidil, a direct vasodilator that is known for its strong blood pressure-lowering effect, but contemporary studies are sparse. The authors retrospectively analyzed 54 inpatients with uncontrolled hypertension despite the combined use of current antihypertensive agents. To investigate the effect of minoxidil when added to other antihypertensive agents, blood pressure was evaluated at the time minoxidil treatment was initiated and at discharge. Minoxidil treatment was associated with a significant reduction in blood pressure from 162.4±15.1/83.2±12.7 mm Hg to 135.8±12.2/72.8±6.9 mm Hg (P<.0001). This effect was sustained across all analyzed subgroups. Although the well-known adverse events of minoxidil limit its widespread use, these data show that minoxidil as a reserve antihypertensive agent still has a niche indication in the particular subgroup of patients with treatment-resistant or uncontrolled hypertension.