Health-related Topics : Medical Biochemistry Tips (9): Hypertension; Myocardial Infarction Biomarkers

Dr. James Manos (MD)

January 5, 2016

Review: Tips in Medical Biochemistry

Volume (9)

CONTENTS

SECONDARY HYPERTENSION

Secondary hypertension

Secondary hypertension – common causes

Diagnostic algorithm for secondary hypertension

ACUTE CORONARY SYNDROME (ACS) & TROPONIN

Cardiac markers for myocardial infarction (MI)

Causes of Acute Troponin Elevation

Acute coronary syndrome – images:

Acute coronary syndrome – ECG (electrocardiogram)

An algorithm to rule out acute myocardial infarction (AMI)/ acute coronary syndrome (ACS) with high sensitivity cardiac troponin (hs-cTn)

GRACE calculator

Algorithm for NSTEMI (non-ST-elevation myocardial infarction)

SECONDARY HYPERTENSION

· Secondary hypertension: a type of hypertension with an underlying, potentially correctable cause. The prevalence of secondary hypertension and the most common etiologies vary by age group.

· About 5 – 10% of adults with hypertension have a secondary cause.

· Symptoms may suggest a secondary etiology (e.g., flushing and sweating suggestive of pheochromocytoma), examination findings (e.g., a renal bruit suggestive of renal artery stenosis), or laboratory abnormalities (e.g., hypokalemia suggestive of aldosteronism).

· Secondary hypertension also should be considered in patients with resistant hypertension, and the early or late onset of hypertension.

· In young adults, particularly women, renal artery stenosis caused by fibromuscular dysplasia is one of the most common secondary etiologies.

· Fibromuscular dysplasia can be detected by abdominal CT or MRI.

· These same imaging modalities can be used to identify atherosclerotic renal artery stenosis, a primary cause of secondary hypertension in older adults.

· In middle-aged adults, aldosteronism is the most common secondary cause of hypertension, and the recommended initial diagnostic test is an aldosterone/renin ratio.

· Up to 85% of children with hypertension have an identifiable cause, most often renal parenchymal disease. Therefore, all children with confirmed hypertension should have an evaluation for an underlying etiology that includes renal ultrasonography.

· Secondary hypertension – common causes:

· a) Children (birth to 12 years old) (70 – 85% presentence of hypertension with an underlying cause): renal parenchymal disease; coarctation of the aorta.

· b) Adolescents (12 to 18 years old) (10 – 15%): renal parenchymal disease; coarctation of the aorta.

· c) Young adults (19 to 39 years old) (5%): thyroid dysfunction (hyperthyroidism); fibromuscular dysplasia; renal parenchymal disease.

· d) Middle-aged adults (40 to 64 years old) (8 – 12%): aldosteronism, thyroid dysfunction; obstructive sleep apnoea; Cushing syndrome; pheochromocytoma.

· e) Older adults (> 65 years old) (17%): atherosclerotic renal artery stenosis; renal failure; hypothyroidism.

· Diagnostic algorithm for secondary hypertension:

· http://www.aafp.org/afp/2010/1215/afp20101215p1471-f1.gif

Acute Coronary Syndrome (ACS) & Troponin

· Cardiac markers for myocardial infarction (MI):

· Troponin I & T (Troponin elevation following cardiac cell necrosis starts within 2 – 3 hours, peaks in approximately 24 hours, and persists for 1 – 2 weeks).

· CK (creatine kinase) – MB (peak approximately in 10 – 24 hours).

· SGOT (AST) (assuming no further cardiac injury occurs, the AST level rises within 6 – 10 hours after an acute heart attack, peaks at 12 – 48 hours, and returns to normal in 3 – 4 days).

· LDH (peak approximately in 72 hours).

· Myoglobin (low specificity; peak approximately in 2 hours).

· Other cardiac markers under investigation: glucogen phosphorylase isoenzyme BB (GPBB; peak approximately in 7 hours) and ischemia-modified albumin (IMA; low specificity).

· Causes of Acute Troponin Elevation:

· I) Acute diseases:

· A) Cardiac and vascular diseases: ACS (acute coronary syndrome); tachyarrhythmias, acute congestive heart failure; aortic valve disease, hypertrophic, obstructive cardiomyopathy (HOCM) with left ventricular hypertrophy (LVH), hypertension- hypotension with arrhythmias; acute aortic dissection, Tako-tsubo cardiomyopathy, abnormalities in coronary vasomotion – including coronary vasospasm; cerebrovascular accident (ischemic stroke, intracerebral hemorrhage, subarachnoid hemorrhage); renal failure; medical ICU patients; gastrointestinal bleeding; hypotension / Shock.

· B) Respiratory diseases: acute PE (pulmonary embolism), pulmonary hypertension, ARDS (adult respiratory distress syndrome).

· C) Cardiac inflammation: endocarditis, myocarditis, pericarditis.

· D) Muscular damage.

· E) Infectious: sepsis; viral illness, parvovirus B19, myocardial involvement in bacterial endocarditis.

· F) Other acute causes of troponin increase:

· i) Kawasaki disease.

· ii) Apical ballooning syndrome.

· iii) Thrombotic thrombocytopenic purpura (TTP).

· iv) Rhabdomyolysis with cardiac injury.

· v) Birth complications in infants: extremely low birth weight; preterm delivery.

· vi) Acute complications of inherited disorders: neurofibromatosis, Duchenne muscular dystrophy; Klippel-Feil syndrome.

· vii) Environmental exposure: carbon monoxide (CO), Hydrogen sulfide (H2S), colchicine.

· II) Chronic diseases:

· a) Chronic congestive heart failure (CHF).

· b) ESRD (end–state renal disease).

· c) Cardiac infiltrative disorders: amyloidosis; sarcoidosis; hemochromatosis; scleroderma.

· d) Hypertension.

· e) Diabetes.

· f) Hypothyroidism.

· III) Iatrogenic disease:

· a) Invasive procedures:

· i) Cardiac: uncomplicated percutaneous coronary intervention (PCI); Htx (heart transplantation); transplant vasculopathy; congenital defect repair; RFCA (radiofrequency catheter ablation); pacing; implantable defibrillator firings; cardiac biopsy; cardiac surgery.

· ii) Non – cardiac: lung resection; postoperative non-cardiac surgery; ERCP.

· b) Non-invasive procedures: cardioversion; lithotripsy.

· c) Pharmacologic sources: adriamycin, 5-fluorouracil, herceptin (for breast cancer), sympathomimetic drugs (e.g., cocaine, ecstasy); chemotherapy; other medications.

· IV) Myocardial injury:

· i) Blunt chest injury; cardiac contusion.

· ii) Endurance athletes; strenuous exercise; vital exhaustion

· iii) Envenomation: snake, jellyfish, spider, centipede, scorpion.

· V) Other causes: burns (particularly when surface area >30%).

· Acute coronary syndrome – images:

· http://medlicker.com/pictures/article_editor/2013/03/12/coronary-arteries-aterosclerosis-1363120204-6ee7c470.jpg

· http://images.slideplayer.us/1/527034/slides/slide_8.jpg

· http://image.slidesharecdn.com/myocardialinfarction1-100426140734-phpapp01/95/myocardial-infarction-1-728.jpg?cb=1272308960

· Acute coronary syndrome – ECG (electrocardiogram):

· http://upload.wikimedia.org/wikipedia/commons/thumb/e/e5/ACS_scheme.jpg/300px-ACS_scheme.jpg

· http://resuscitation-guidelines.articleinmotion.com/uploads/els_articles/S0300-9572(10)00442-9/assets/gr1.jpg