Cardiovascular Diseases

From Molecular Pharmacology to Evidence-Based Therapeutics

Y. Robert Li

• Publisher: Wiley
• Year: 2015
• Print ISBN: 9780470915370
• eBook ISBN: 9781118889916
• Edition: 1
• Topic: Medicine
• Subtopic: Cardiology

Written in an accessible style and consistent format, the book covers both the fundamentals and advances in the pharmacology of cardiovascular drugs, as well as their integrated applications in the management of individual cardiovascular diseases.

•    Integrates fundamentals and recent advances regarding cardiovascular drugs, blending basic and clinical sciences needed to effectively understand and treat cardiovascular diseases
•    Facilitates understanding of drug action and mechanism by covering physiology / pathophysiology and pharmacology
•    Includes guidelines and algorithms for pharmacotherapeutic management of cardiovascular diseases
•    Uses case presentations and study questions to enhance understanding of the material
•    Serves as a resource for pharmaceutical and medical students and researchers interested in cardiovascular issues

Unit III
Hypertension and Multitasking Cardiovascular Drugs

6
Overview of Hypertension and Drug Therapy

6.1 Introduction

Hypertension is the most common condition seen in primary care settings and leads to myocardial infarction, stroke, renal failure, and death if not detected early and treated appropriately. Advances in risk factor identification, molecular pathophysiology, and mechanistically based therapies, especially pharmacological agents, have led to significant improvement of hypertension management. To set a stage for the subsequent discussion of the molecular pharmacology of antihypertensive drugs and evidence-based therapeutics of hypertension in the remaining chapters of Unit III, this chapter provides an overview on several aspects of hypertension, including definition, epidemiology, pathophysiology, and mechanistically based drug therapy. Because the different drug classes used for treating hypertension are also commonly employed in the management of other cardiovascular diseases, these multitasking cardiovascular drugs are considered in separate chapters (Chapters 7–11). Following the discussion of these multitasking drugs, the current guidelines on hypertension management are given in Chapter 12.

6.2 Definitions, Classifications, and Epidemiology of Hypertension

Hypertension, when not specified, typically refers to increased blood pressure in systemic circulation and hence is also known as systemic arterial hypertension. In addition to systemic circulation, hypertension also occurs in pulmonary and portal circulations. This section defines hypertension and provides an overview of its epidemiology.

6.2.1 Definitions and Classifications

6.2.1.1 The JNC7 Classification of Blood Pressure

Hypertension, also known as high blood pressure, is defined as systolic pressure ≥140 mm Hg and/or diastolic pressure ≥90 mm Hg. Based on the Seventh Report of the Joint National Committee on the Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC7), blood pressure is classified into four categories (Table 6.1). According to JNC7, hypertension is further classified into two stages, that is, stage 1 and stage 2.

Table 6.1 The JNC7 classification of blood pressure

Blood pressure classification	Systolic blood pressure (mm Hg)	Diastolic blood pressure (mm Hg)
Normal	<120	and <80
Prehypertension	120–139	or 80–89
Stage 1 hypertension	140–159	or 90–99
Stage 2 hypertension	≥160	or ≥100

6.2.1.2 Hypertension Crisis

Hypertension crisis is a term that refers to critical clinical conditions of severely elevated blood pressure. Hypertensive crisis can present as hypertensive urgency or as hypertensive emergency.

Hypertensive urgency is a situation where the blood pressure is severely elevated (≥180 mm Hg for systolic pressure or ≥110 mm Hg for diastolic pressure), but there is no associated organ damage. Individuals experiencing hypertensive urgency may or may not experience one or more of these symptoms: severe headache, shortness of breath, nosebleeds, and severe anxiety.

The term hypertensive emergency refers to severely elevated blood pressure levels that are damaging organs, which can be manifested as stroke, myocardial infarction, renal failure, and loss of consciousness. Hypertensive emergencies generally occur at blood pressure levels exceeding 180 mm Hg (systolic) or 120 mm Hg (diastolic) but can also occur at even lower levels in patients whose blood pressure had not been previously high.

6.2.1.3 Primary and Secondary Hypertension

Based on etiology, hypertension is classified into primary and secondary hypertension. In 90–95% of hypertensive patients, a single reversible cause of the elevated blood pressure cannot be identified, and hence, the patients are said to have primary (or essential) hypertension. In the remaining 5–10% of cases, a cause can be identified, and hence, the patients are said to have secondary hypertension. Common causes of secondary hypertension are listed below, and the underlying mechanisms are given in Table 6.2:

• Kidney diseases, especially chronic kidney disease [1]
• Primary aldosteronism [2]
• Cushing’s syndrome [3]
• Pheochromocytoma [4]

Table 6.2 Major mechanisms of secondary hypertension

Cause	Major mechanism
Kidney diseases	Increased renin release due to decreased perfusion
Primary aldosteronism	Water and salt retention due to increased levels of aldosterone
Cushing’s syndrome	Water and salt retention due to increased release of corticosteroids
Pheochromocytoma	Release of catecholamines from the tumors of the adrenal chromaffin cells

6.2.1.4 Systemic and Pulmonary Hypertension

The term hypertension is often used synonymously with systemic arterial hypertension. Systemic arterial hypertension is the predominant form of hypertension. It should be kept in mind that hypertension can also occur in pulmonary and portal circulations. Pulmonary hypertension refers to an abnormal elevation in pulmonary artery pressure. It may be the result of left-side heart failure, pulmonary parenchymal or vascular disease, thromboembolism, or a combination of these factors [5]. Pulmonary hypertension is the most common cause of right ventricular enlargement and failure.

6.2.2 Epidemiology and Health Impact of Hypertension

6.2.2.1 Epidemiology

Hypertension currently affects approximately 78 million American adults (one in three adults) and over one billion people worldwide. Many risk factors for development of hypertension have been identified, including age, ethnicity, family history of hypertension and genetic factors, lower educ...

Table of contents

• Cover
• Title page
• Table of Contents
• Preface
• List of Abbreviations
• Unit I: General Introduction
• Unit II: Dyslipidemias
• Unit III: Hypertension and Multitasking Cardiovascular Drugs
• Unit IV: Ischemic Heart Disease: Stable Ischemic Heart Disease
• Unit V: Ischemic Heart Disease: Acute Coronary Syndromes
• Unit VI: Heart Failure
• Unit VII: Cardiac Arrhythmias
• Unit VIII: Ischemic Stroke
• Index
• End User License Agreement