Pathophysiology, clinical aspects, and treatment of hypertensive crises

Prevalence, Determinants and Clinical Significance of Cardiac Troponin-I Elevation among Individuals with Hypertensive Emergency: A Prospective Observational Study

Introduction

Cardiac troponin-I (cTnI) elevation release during hypertensive emergencies (HEs) is a frequent epiphenomenon that may tangle management of individuals being treated for HEs. The primary objective of this study was to determine the prevalence, determinants, and clinical significance of cTnI elevation and secondary objective was to find out the prognostic significance of cTnI elevation in patients admitted for HE in the emergency department (ED) of a tertiary care hospital.

Methodology

The investigator has employed the quantitative research approach with a prospective observational descriptive design. The population of this study comprised of 205 adults, which included both males and females, who were more than or 18 years of age. The subjects were selected by non-probability purposive sampling technique. The study was conducted from August 2015 to December 2016 (16 months). Ethical permission was obtained from the Institutional Ethics Committee (IEC), Max Super Speciality Hospital, Saket, New Delhi and well-informed written consents were taken from the subjects. The analysis of data was done with the help of SPSS, version 17.0.

Results

Out of 205 patients in the study, cTnI elevation was found in 102 patients (49.8%). Moreover, there was increased duration of stay in the hospital in patient with elevated cTnI level with mean duration stay 1.55 ± 0.82 (p <0.001). In addition, cTnI elevation was associated with increased mortality, 11 out of 102 in an elevated cTnI group (10.8%) with p <0.002.

Conclusion

It was found that cTnI elevation in individuals affected by various clinical factors. The authors highlighted a high frequency of mortality among the individuals presented with HE with elevated cTnI level, whereas the presence of cTnI was associated with greater odds of death.

How to cite this article

Gupta K, Kiran M, Chhabra S, Mehta M, Kumar N. Prevalence, Determinants and Clinical Significance of Cardiac Troponin-I Elevation among Individuals with Hypertensive Emergency: A Prospective Observational Study. Indian J Crit Care Med 2022;26(7):786-790.

Hypertensive crisis in children

Hypertensive crisis is rare in children and is usually secondary to an underlying disease. There is strong evidence that the renin-angiotensin system plays an important role in the genesis of hypertensive crisis. An important principle in the management of children with hypertensive crisis is to determine if severe hypertension is chronic, acute, or acute-on-chronic. When it is associated with signs of end-organ damage such as encephalopathy, congestive cardiac failure or renal failure, there is an emergent need to lower blood pressures to 25-30% of the original value and then accomplish a gradual reduction in blood pressure. Precipitous drops in blood pressure can result in impairment of perfusion of vital organs. Medications commonly used to treat hypertensive crisis in children are nicardipine, labetalol and sodium nitroprusside. In this review, we discuss the pathophysiology, differential diagnosis and recent developments in management of hypertensive crisis in children.

Severe Hypertension in the Emergency Department Patient

Severely elevated blood pressure is a common clinical problem en-countered in the Emergency Department. It is often difficult for physicians to differentiate between patients who need emergent blood pressure reduction, requiring the use of intravenous agents and in-tensive monitoring, and those for whom careful, slow reduction in BP is more appropriate. The optimal assessment and management of these patients is reviewed here, with an emphasis on clinical strategies that will most efficiently identify those at greatest risk.

Angiotensin-converting enzyme i/d polymorphism in patients with malignant hypertension

The angiotensin-converting enzyme (ACE) gene has been implicated in the manifestation of the phenotype of malignant hypertension (MH). In 1990 the ACE gene polymorphism characterized by the insertion or deletion of a 287-base pair fragment in the 17q23 chromosome was identified. The DD genotype is associated with increased tissue and circulating ACE levels and elevated angiotensin II. ACE polymorphism was studied in 48 patients with MH, 25 patients with non-MH, and a control group of 78 normotensive individuals by real-time polymerase chain reaction using the LightCycler system (Roche Diagnostics Corporation, Indianapolis, IN). The DD genotype was found statistically more frequently in MH patients than controls (p=0.028; odds ratio, 2.5; confidence interval, 1.1-5.5). Presence of the DD genotype of the ACE gene is more frequent in MH patients than in controls, indicating that this genotype could be a significant risk factor and a predictor for the development of MH.

Comprehensive management of hypertensive emergencies and urgencies

Despite advances in chronic hypertension management, hypertensive emergencies and urgencies remain as serious complications. Much of this relates to poor compliance with effective antihypertensive management. Hypertensive emergencies and urgencies can also be seen as the initial manifestations of hypertension in pregnancy and in the perioperative period. Multiple classes of intravenous antihypertensive drugs are available to treat hypertensive emergencies, and specific agents may have an advantage in a given clinical situation. Orally active agents are used to treat hypertensive urgencies, and include clonidine, angiotensin-converting enzyme inhibitors, and labetalol. Most patients respond to drug therapy, but problems may arise related to a rapid normalization of blood pressure.

Hypertensive emergencies

In summary, patients presenting with a true hypertensive emergency should be diagnosed quickly and promptly started on effective parenteral therapy (typically nitroprusside 0.5 microgram/kg/min or fenoldopam 0.1 microgram/kg/min) in an intensive care unit. Blood pressure should be reduced about 25% gradually over 2 to 3 hours. Oral antihypertensive therapy (often with an immediate-release calcium antagonist) can be instituted after 6 to 12 hours of parenteral therapy, and consideration should be given to secondary causes of hypertension after transfer out of the intensive care unit. Because of advances in antihypertensive therapy and management, "malignant hypertension" should be truly malignant no longer.

Hypertensive emergencies

A hypertensive emergency is a situation in which uncontrolled hypertension is associated with acute end-organ damage. Most patients presenting with hypertensive emergency have chronic hypertension, although the disorder can present in previously normotensive individuals, particularly when associated with pre-eclampsia or acute glomerulonephritis. The pathophysiological mechanisms causing acute hypertensive endothelial failure are complex and incompletely understood but probably involve disturbances of the renin-angiotensin-aldosterone system, loss of endogenous vasodilator mechanisms, upregulation of proinflammatory mediators including vascular cell adhesion molecules, and release of local vasoconstrictors such as endothelin 1. Magnetic resonance imaging has demonstrated a characteristic hypertensive posterior leucoencephalopathy syndrome predominantly causing oedema of the white matter of the parietal and occipital lobes; this syndrome is potentially reversible with appropriate prompt treatment. Generally, the therapeutic approach is dictated by the particular presentation and end-organ complications. Parenteral therapy is generally preferred, and strategies include use of sodium nitroprusside, beta-blockers, labetelol, or calcium-channel antagonists, magnesium for pre-eclampsia and eclampsia; and short-term parenteral anticonvulsants for seizures associated with encephalopathy. Novel therapies include the peripheral dopamine-receptor agonist, fenoldapam, and may include endothelin-1 antagonists.

Genetic mapping of modifier loci affecting malignant hypertension in TGRmRen2 rats

BACKGROUND

Genetic background has a major influence on the manifestation of multifactorial diseases such as hypertension in which severe complications may be caused through an interaction with additional factors, which may be genetically determined. We have previously described a genetic model of malignant hypertension (MH) in rats carrying the mouse Ren2 gene (TGRmRen2-27), in which the phenotype is dependent on the genetic background.

METHODS

Using a single homozygous TGRmRen2-27 male as transgene donor, we produced two F1 populations with (a) 100% penetrance of MH in progeny heterozygous for the Fischer F344 genetic background and (b) 58.5% penetrance in progeny heterozygous for the Lewis genetic background. To identify the modifier loci affecting the phenotype, a cohort of 252 males was produced by breeding the same single male with Fischer-Lewis F1 females. The progeny were phenotyped for clinical and pathological features of MH.

RESULTS

Genome-wide screening and quantitative trait loci (QTL) analysis identified two loci, on chromosome 10 (LOD 4.4) and on chromosome 17 (LOD 3.9) close to the Ace and At1 genes, respectively, which contribute to the lethal MH phenotype. Their influence on mortality was consistent with a multiplicative effect of the two loci. In addition, we found higher plasma angiotensin-converting enzyme activity in progeny receiving the Fischer allele than in progeny receiving the Lewis allele (123.5 +/- 9.5 vs. 91.8 +/- 4.9 U/liter, P < 0.01), suggesting the association of angiotensin-converting enzyme and MH.

CONCLUSIONS

Our study demonstrates the application of a transgene as a "major gene" to facilitate the identification of modifier loci, which can affect the phenotype of MH, and reveals Ace and At1 as candidate genes involved in the manifestation of the MH phenotype.

Inhibition of tissue angiotensin converting enzyme activity prevents malignant hypertension in TGR(mREN2)27

BACKGROUND

Activation of the renin-angiotensin system has been implicated strongly in the transition from benign to malignant hypertension. However, the concomitant rise in blood pressure might also have a direct effect on the vascular wall by initiating fibrinoid necrosis and myointimal proliferation. Ascertaining the relative importance of these two factors in this process has proved difficult. TGR(mREN2)27 heterozygotes (HanRen2/Edin- -) have previously been shown to develop malignant hypertension spontaneously and exhibit the characteristic features of human malignant hypertension.

OBJECTIVE

Tissue renin-angtiotensin systems have been implicated in the pathogenesis of malignant hypertension. We set out to determine whether inhibition of this system might protect against development of the disease in a rat model.

METHOD

Male TGR(mREN2)27 heterozygotes (n = 24) were given a non-hypotensive dose of the angiotensin converting enzyme inhibitor ramipril (5 microg/kg per day) from 28 to 120 days of age, untreated rats acting as controls (n = 40). The incidences of malignant hypertension were compared. Systolic blood pressure was measured by tail-cuff plethysmography during treatment; tissue and plasma angiotensin converting enzyme levels and renal histological changes were assessed at the end of the treatment period or upon development of malignant hypertension.

RESULTS

Sixty-three per cent of control rats and 4% of angiotensin converting enzyme inhibitor-treated rats had developed malignant hypertension by 120 days despite there having been no significant difference in systolic blood pressure throughout the course of treatment. Angiotensin converting enzyme activities in kidney, heart and resistance vessels, though not that in plasma, were significantly lower in the treated rats. The degree of medial wall thickening did not differ between the two groups whereas evidence of tissue injury (e.g. intimal fibrosis, fibrinoid necrosis and nephron injury) was significantly less common among rats in the angiotensin converting enzyme inhibitor-treated group.

CONCLUSIONS

Tissue angiotensin converting enzyme inhibition at a non-hypotensive dose almost completely prevented mortality from malignant hypertension and significantly reduced tissue injury in this model, implicating angiotensin II rather than high blood pressure as the principal 'vasculotoxic' agent in malignant hypertension.

Management of hypertension in acute intracerebral hemorrhage

Hypertension commonly occurs in the acute period following spontaneous intracerebral hemorrhage. Management of this hypertension is controversial. Some advocate lowering blood pressure to reduce the risk of bleeding, edema formation, and systemic hypertensive complications, whereas others advocate allowing blood pressure to run its natural course as a protective measure against cerebral ischemia. This article reviews the pertinent clinical and experimental data regarding these issues and briefly discusses the use of antihypertensive agents commonly administered in this setting.

Randomized, prospective trial of fenoldopam vs sodium nitroprusside in the treatment of acute severe hypertension. Fenoldopam Study Group

OBJECTIVE

To compare the safeties and efficacies of IV fenoldopam (FNP) vs sodium nitroprusside (NTP) in severe acute hypertension.

METHODS

A prospective, randomized, open-label, multicenter international trial, at 24 academic medical centers, was conducted. The participants were adult patients (21-80 years of age) who had supine diastolic blood pressures (DBPs) > or = 120 mm Hg, were capable of written informed consent, and did not have selected exclusion criteria. The subjects were randomized to either FNP or NTP therapy; DBP was titrated to 95-110 mm Hg, or a maximum reduction of 40 mm Hg for very high pressures. Infusions were maintained for at least six hours, then the patients were weaned off the IV therapy and oral medication was started. Measurements included BP, heart rate, and duration of study drug infusion and frequency of side effects or complications.

RESULTS

A total of 183 patients (90 FNP, 93 NTP) were enrolled. Fifteen patients from each arm were excluded from efficacy analysis due to protocol violation. There was no significant difference in baseline characteristics. The two antihypertensive agents were equivalent in controlling and maintaining DBP. Systolic blood pressure (SBP) was reduced to a slightly greater degree for the NTP-treated patients during the initial (0.5-1-hr) study period, and both SBP and DBP were reduced more for the FNP-treated patients in the subset receiving infusions during the 12-24-hour period. The adverse effect profiles of the drugs were similar, as were the times to achieve target pressure, with no clinically relevant difference.

CONCLUSIONS

For patients who had acute severe hypertension, FNP and NTP were equivalent in terms of efficacy and acute adverse events. Because of a unique mechanism of action, FNP may have advantages in selected subsets of patients. Further studies may be indicated in patient populations with pure "hypertensive emergencies."

Evaluation of the efficacy and safety of oral nicardipine in treatment of urgent hypertension: a multicenter, randomized, double-blind, parallel, placebo-controlled clinical trial

This study was a prospective, randomized, double-blind, placebo-controlled clinical trial designed to evaluate the safety and efficacy of oral nicardipine for the treatment of urgent hypertension in the emergency department. Of 57 patients with urgent hypertension 53 patients were enrolled: 36 men and 17 women, 43 black and 10 white, age range 48 +/- 11 years, and diastolic blood pressure 128 +/- 7 mm Hg. Patients were randomly assigned to receive 30 mg nicardipine or placebo in blind fashion followed by 30 mg open-label nicardipine in nonresponders. Responders to one or two doses of nicardipine received 30 or 40 mg nicardipine three times a day for 1 week after discharge from the emergency department. Adequate blood pressure reduction, defined as a reduction of diastolic blood pressure to less than 100 mm Hg or by at least 20 mm Hg, was achieved in 65% and 22% of patients who received 30 mg nicardipine or placebo (p = 0.002). Adequate blood pressure reduction after administration of open-label nicardipine occurred in 76% of the nonresponders to placebo. Blood pressure reductions were maintained at 1 week after discharge. The drug was well tolerated, and no significant adverse events occurred. We conclude that oral nicardipine is a safe and effective drug for the initial treatment of urgent hypertension.

Management of hypertensive crises

Hypertensive crises are now uncommon in developed countries, and few doctors will have experience in their management. A review of the drugs used by clinicians in Scotland suggests considerable diversity in approach but broadly follows the best advice that is available in the literature. For emergencies such as hypertensive encephalopathy and hypertension associated with aortic dissection in which irreversible damage would occur within hours if left untreated, patients should probably be admitted to Intensive Care Units and be given nitroprusside. Similarly nitroprusside or nitroglycerin would be appropriate choice for hypertension that is complicated by acute left ventricular failure. By contrast if the risk to the patient is measured in days rather than hours then oral therapy will be quite sufficient. Atenolol or nifedipine retard can safely be given as initial treatment for uncomplicated malignant hypertension, and nifedipine retard can be used for the milder cases of encephalopathy or heart failure. The use of sublingual drugs in the management of hypertensive emergencies and urgencies cannot be recommended as the fall in blood pressure is both unpredictable and uncontrolled with the consequent and unacceptable risk of organ ischaemia.

A genetic model of malignant phase hypertension in rats

A genetic model of malignant phase hypertension in rats is described which closely parallels the natural history of untreated human malignant phase hypertension. Although the factors initiating transition from essential hypertension to the accelerated phase in humans remain unknown, we report the characteristics of a genetically determined and reproducible phenotype which was found to result from a cross between hypertensive transgenic Ren-2 rats and normotensive Sprague-Dawley (Edinburgh) rats. Male F1 hybrids developed malignant phase hypertension with a penetrance of 73.5% (95% confidence limits 65.7 to 81.3%) by 100 days of age. Phenotypic features included an accelerated rise in blood pressure, fibrinoid necrosis, activation of the renal renin-angiotensin system and microangiopathic hemolytic anemia. In an analytical cross no significant difference in blood pressure was observed between malignant phase and non-malignant phase animals prior to transition, implying that a factor in addition to hypertension appears necessary for inducing transition to the malignant phase phenotype. Segregation of the malignant phenotype suggested that susceptibility is determined by at most two genetic loci.

Spontaneous development of malignant phase hypertension in transgenic Ren-2 rats

Spontaneous development of malignant phase hypertension in TGR(mREN2)27 heterozygotes occurs as a consequence of crossing TGR(mREN2)27 homozygotes with Edinburgh Sprague-Dawley rats. Similarities to human malignant phase hypertension are seen with an accelerated rise in blood pressure, fibrinoid necrosis of renal afferent arterioles, renal failure and evidence of renin-angiotensin system activation. It appears that introduction of an additional genetic factor or factors into a monogenic model of hypertension results in malignant phase hypertension.

Advances in pharmacotherapy: treatment of hypertensive crisis

A hypertensive crisis can be caused by many factors. Frequently, the mechanism involved is complex and highly variable among patients. Without drug therapy, this condition is associated with very high mortality and morbidity. There are a number of oral and intravenous hypotensive agents available, which can effectively control blood pressure in a hypertensive crisis. The relative advantages and disadvantages of each treatment option is discussed.

Treatment of hypertensive emergency. Comparison of a new dosage form of the calcium antagonist nitrendipine with nifedipine capsules

OBJECTIVE

To present the efficacy and tolerability of a new oral dosage form of the calcium antagonist nitrendipine compared to nifedipine capsules in patients with hypertensive emergency.

DESIGN

Multicenter randomized double blind clinical study.

SETTING

23 study centres (hospitals) in Germany.

PATIENTS

161 patients between 20 and 70 years with acutely elevated blood pressure (systolic 200-250 mmHg, diastolic between 110-140 mmHg) with and without concomitant clinical symptoms.

INTERVENTIONS

Double blind treatment with 10 mg nifedipine or 5 mg nitrendipine. Nifedipine was administered as capsules, nitrendipine was given from a small plastic tube (vial), containing 1 ml alcoholic solution. Every patient received in addition to the test medication a placebo corresponding to the other product. Patients with insufficient treatment after 45 min were given either an additional capsule of 10 mg nifedipine or a further vial containing 5 mg nitrendipine according to their group and maintaining the double dummy procedure.

MEASUREMENTS AND RESULTS

Blood pressure and heart rate were measured repeatedly during 4 h, before and 90 min after beginning of the treatment a 12 channel resting ECG was recorded. At 45 min after administration the blood pressure had fallen significantly from 216.0/117.4 mmHg to 170.0/93.3 mmHg under nifedipine and from 216.9/117.3 mmHg to 177.4/94.4 mmHg under nitrendipine. 61.6% of the nifedipine patients and 58.8% of the nitrendipine patients had already reached blood pressure values < 180/100 mmHg after 45 min and in both groups 83% of these patients were still in this limit at the end of the observation period after 4 h. Tolerability was very good in both groups.

CONCLUSION

The new dosage form of nitrendipine (vial with 1 ml of alcoholic solution) represents an alternative in the treatment of hypertensive emergency.

Single-dose sublingual nifedipine as the only treatment in hypertensive urgencies and emergencies

One hundred and eighteen patients with hypertensive urgencies and emergencies and diastolic blood pressure (DBP) at least 120 mm Hg by the cuff method were seen at the Emergency Care Department; none had received calcium channel blockers during the previous twelve hours. Patients with DBP of 120 to 139 mm Hg received 10 mg of sublingual nifedipine; patients with left ventricular hypertrophy or failure, renal disease, hypertensive encephalopathy, angina, papilledema, or a DBP over 140 mm Hg received 20 mg of the drug. The criterion for control was the achievement of a DBP of 100 mm Hg or less within sixty minutes of receiving sublingual nifedipine and maintenance of the effect until discharge. Control was achieved in all patients; a sixty-three-year-old man died of a brain hemorrhage after pulmonary edema and a DBP of 210 had been controlled; the other 117 were discharged to their attending physicians, either as outpatients or to a hospital ward. No patient developed hypotension, clinical or electrocardiographic signs of myocardial ischemia, or clinical signs of neurologic dysfunction. Practical, fast, safe, and dependable control of hypertensive urgencies and emergencies has made sublingual nifedipine the treatment of choice of such patients in the Emergency Care Department.

Control of hypertensive emergencies

Although uncommon, hypertensive emergencies require prompt recognition and treatment to reduce very high morbidity and mortality rates. Admission to an intensive care unit for treatment and monitoring is essential for optimal care. A Swan-Ganz catheter is often helpful in management. Intravenous nitroprusside sodium (Nipride, Nitropress) is probably the drug of choice for hypertensive emergencies other than those due to eclampsia or pheochromocytoma.

Rapid-acting parenteral antihypertensive agents

Parenteral antihypertensive agents are useful in those clinical situations where rapid reduction of blood pressure is necessary or where treatment with oral antihypertensive medications is not feasible. Given the diverse selection of parenteral antihypertensive drugs now available, therapy can be individualized. The presence of concurrent diseases will often influence the decision-making process regarding choice of an agent. Complications of parenteral antihypertensive therapy can arise from the intrinsic properties of the various drugs or the development of severe hypotension. Gradual lowering of blood pressure, in conjunction with careful clinical evaluation, will minimize the risks of acute parenteral antihypertensive therapy. Given that parenteral antihypertensive therapy often needs to be replaced by oral therapy, those drugs that can be used both parenterally and orally may have an advantage.