Cardiology

Published on 24/06/2015 by admin

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Last modified 24/06/2015

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Cardiac conditions are very commonly encountered in the long case setting. Given that cardiac disease is the most common morbidity in the world’s adult population, a cardiac condition could be encountered as the main pathology or an associated condition in the long case setting. Common cardiology long cases the candidate should be well versed in are: heart failure, ischaemic heart disease, arrhythmias and hypertension. Also important are valve disease and associated clinical decision-making processes, including timing of surgery if indicated in the patient with a cardiac valvular pathology.

HYPERTENSION

Case vignette

A 57-year-old man is admitted to hospital with severe chest pain. The pain is of sudden onset, tearing in character and radiating to the back. He is diaphoretic and anxious. On examination his pulse is regular at 110 bpm. His heart sounds are normal and the chest is clear. His blood pressure in the right arm is 190/100 mmHg and in the left arm 170/70 mmHg.

Approach to the patient

Examination

Check the blood pressure and look for a postural drop. If the blood pressure is very high, check the other arm and repeat the measurement at the end of the physical examination for confirmation.

Investigations

Creatinine clearance needs to be checked to clarify renal function but does not really help to distinguish between primary renal disease causing high blood pressure and renal impairment secondary to hypertensive nephrosclerosis. If there is no significant proteinuria or renal failure, a trial of effective blood pressure lowering for 6 months can be given. Deterioration of renal function at any stage is an indication for investigation. The additional investigations in this setting include a renal ultrasound (looking for renal shrinkage suggesting chronic renal failure or renovascular disease, or enlarged kidneys suggesting conditions such as polycystic kidney disease), a DTPA scan (to assess renal perfusion) and a renal arterial Doppler study (to exclude renal artery stenosis). If clinical evidence indicates renal artery stenosis, further study with computed tomography (CT) or magnetic resonance (MR) angiography is indicated.
The major endocrine investigation is the aldosterone/renin ratio, to detect primary hyperaldosteronism. This is now believed to account for 10–15% of people presenting with essential hypertension, but this does not mean that they all need adrenalectomy. Other endocrine investigations include: serum renin index (to exclude renin hypersecretion) and 24-hour urinary cortisol (to screen for Cushing’s syndrome).
If there is suspicion (tachycardia, palpitations, sweating, anxiety, postural hypotension) of phaeochromocytoma, perform serum catecholamine level, urinary metanephrines and urinary vanillylmandelic acid level.

Management

It is not wise to commence treatment at the first diagnosis itself unless there is malignant hypertension, end-organ damage (see box) or significant other vascular risk factors, or comorbidity. (Treat with antihypertensive agents if the diastolic pressure is > 100 mmHg, or systolic > 200 mmHg, or systolic pressure > 160 mmHg together with end-organ damage. The presence of other cardiovascular risk factors would be another indication for treatment.) Observation for 3–6 months with recommendation of non-pharmacological methods such as progressive muscle relaxation, weight reduction (if relevant), reduction of alcohol consumption, salt restriction and regular physical exercise would suffice initially. It is important to advise the patient against smoking. If present, hyperlipidaemia and diabetes should be treated. If the blood pressure remains elevated (>140/90 mmHg) despite adequate lifestyle modification (or due to failure of lifestyle modification), pharmacotherapy should be initiated.

Selection of the appropriate antihypertensive agent should be guided by several factors, including: the patient’s comorbidities, age, sex, ethnic background and drug allergies. Initially an attempt should be directed at monotherapy, and the commonly used agents are thiazide diuretics, beta-blockers, calcium channel blockers, angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor blocker (ARB). If monotherapy is inadequate, combination therapy can be considered. An ACE inhibitor with a diuretic, or a beta-blocker with a diuretic, are two such combinations. There are combination pills containing an ACE inhibitor or an ARB together with a thiazide diuretic that can be prescribed. Hypertension that is not well controlled with conventional agents even with up titration and combination warrants further investigation and the addition of potent, less commonly used agents such alpha receptor blockers, centrally acting agents or arterial vasodilators.

Comorbidities that can influence the choice of therapy

Diabetes mellitus—ACE inhibitors are the most suitable agents. Where ACE inhibitors are not tolerated, the other options to consider include ARBs and calcium channel blockers. Beta-adrenergic receptor blockers and thiazide diuretics can interfere with glycaemic control. ACE inhibitors and ARBs have significant and useful synergy in severe high blood pressure and diabetic nephropathy.

Gout—beta-blockers, ACE inhibitors, calcium channel blockers and alpha-blockers are suitable. Thiazide diuretics can exacerbate gout.

Dyslipidaemia—ACE inhibitors, calcium channel blockers and alpha-blockers are recommended. Beta-blockers may be less desirable due to their adverse effects on the lipid profile.

Ischaemic heart disease—diuretics, beta-blockers, calcium channel blockers, ACE inhibitors and ARBs are suitable because of their protective properties in coronary vascular disease.

Congestive cardiac failure—ideal agents include beta-blockers, ACE inhibitors, ARBs and diuretics, which also have proven value in the management of cardiac failure.

Peripheral vascular disease—calcium channel blockers, alpha-adrenergic receptor blockers and diuretics are desirable agents. Beta-blockers are contraindicated.

Pregnancy—for mild hypertension in pregnant patients, methyldopa and the alpha- and beta-adrenergic receptor blocking agent labetolol are good choices. In preeclampsia, nifedipine is a suitable agent; however, urgent delivery of the baby is an absolute requirement. Severe hypertension in the pregnant patient can be managed with intravenous (IV) hydralazine.

Adverse effects of some antihypertensive agents

It is important to have a commanding knowledge of the properties and adverse effects of the commonly used antihypertensive agents. Below is a list of adverse effects seen with different classes of antihypertensive agents, together with some important properties of selected agents.

ISCHAEMIC HEART DISEASE AND ACUTE MYOCARDIAL INFARCTION

Sometimes examiners like to test candidates’ knowledge of the management of common acute medical conditions. No condition is more common than acute myocardial infarction in the physician trainee’s case repertoire, and the candidate is expected to be thoroughly familiar with the management of this condition.

Case vignette

A 45-year-old man presents with retrosternal chest tightness of 3 hours’ duration. The pain is dull in nature, 7/10 in severity and radiating along the left arm. The onset was at rest. He also complains of progressive dyspnoea and associated nausea. He denies any cardiovascular risk factors apart from a strong family history. On examination his pulse rate is 100 bpm, low in volume and regular. His blood pressure is 90/60 mmHg. There are fine crepitations bibasally in the lung fields. The ECG shows deep T wave inversions in leads I, III and aVF.

Upon stabilisation the patient is admitted to the coronary care unit (CCU). His Killip class is 2 (see box). He is managed on aspirin, metoprolol 12.5 mg twice daily and IV heparin. While in CCU his blood pressure drops to 70/40 mmHg and pulse rate to 40 bpm. His pain is progressive and the ECG shows further deepening of the T wave inversions and new ST depression in the said leads, and also in leads aVR, V1 and V2.

He is commenced on an IV glycoprotein IIb/IIIa inhibitor and referred for early catheterisation. Catheterisation reveals occlusion of the posterior descending branch of the right coronary artery, which is successfully reopened by balloon angioplasty and stenting. On day 2 he develops fever and pleuritic chest pains.

On day 3 he develops acute pulmonary oedema and cardiogenic shock. Auscultation reveals a new harsh pansystolic murmur audible all over the precordium.

(Adapted from Killip T, Kimball J T 1967 Treatment of myocardial infarction in coronary care unit. A two-year experience with 250 patients. American Journal of Cardiology 20:457)
(Adapted from Killip T, Kimball J T 1967 Treatment of myocardial infarction in coronary care unit. A two-year experience with 250 patients. American Journal of Cardiology 20:457)

Approach to the patient

Examination

First and foremost, check the vital signs and establish haemodynamic stability. If the patient is having an acute episode of coronary ischaemia (or other emergency such as pneumothorax, pulmonary embolus) they may become rapidly unstable, with haemodynamic compromise or cardiopulmonary arrest.
Once the patient is stable, perform a detailed cardiovascular examination. Look in the fundus for hypertensive or diabetic changes. Listen to the heart for additional sounds such as the third and fourth heart sounds. Listen to the lung bases for crepitation of congestion.

Management

In any acute myocardial infarction the first priority is to assess the patient’s clinical stability and assess the requirement for, and urgency associated with, coronary revascularisation. Remember: patients presenting with an infarction could present with acute pulmonary oedema, cardiogenic shock, malignant ventricular tachyarrhythmias or severe bradycardia. Once the patient’s haemodynamic stability and cardiac rhythm stability are established, perform an urgent ECG to confirm the diagnosis and identify the nature of the infarction—whether it is an ST segment elevation infarction (STEMI) or a non-ST segment elevation infarction (non-STEMI).

STEMI

If the infarction is a STEMI, urgent reperfusion therapy is needed. Acute reperfusion therapy could be primary percutaneous transluminal coronary angioplasty (primary PTCA) with insertion of a stent or thrombolysis. If the centre offers a primary angioplasty service and the patient fulfils the criteria (see box), urgent transfer to the cardiac catheterisation laboratory should take place. Patients presenting in the first 4–6 hours of onset of chest pain are considered suitable for primary PTCA. Previous coronary artery bypass grafts, peripheral vascular disease, untreatable terminal illness and dementia are exclusion criteria for this procedure.
If primary PTCA is not an option, the patient should be thrombolysed with the relevant thrombolytic agent. If the patient presents within the first hour after the onset of chest pain, thrombolysis would be a preferred option (the ‘golden hour’ phenomenon). Usually a recombinant tissue plasminogen activator (rTPA) or an analogue is given to the patient immediately. Streptokinase is an alternative for patients over the age of 65 or those with evidence of an inferior myocardial infarction presenting after 4 hours of the onset of chest pain. Those who have been treated with streptokinase previously should not be given streptokinase again, due to the heightened risk of an allergic reaction.
The ECG criteria for primary PTCA and thrombolysis are similar (see box), but thrombolysis may be useful up to 12 hours or even 24 hours after the onset of chest pain.
If the decision is made to administer thrombolytics, the patient should not have any contraindications (e.g. risk of haemorrhage or allergy) to such therapy. If thrombolytic therapy has not been effective and the patient is a strong candidate for reperfusion therapy, attempts should be made to organise urgent rescue angioplasty.
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Figure 3.3 Coronary angiogram of occluded artery (A) before primary PTCA (B) during primary PTCA (C) after primary PTCA; (D) ECG showing ST segment elevation in the antroseptal and lateral leads, indicating complete occlusion of the LAD artery

Non-STEMI

If a non-STEMI, the patient should be managed initially with anticoagulation and antiplatelet therapy. The patient should subsequently be referred for early coronary catheterisation.
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