**3. Dilated cardiomyopathy**

Dilated cardiomyopathy (DCM) is defined by cardiac enlargement with impaired systolic function of one or both ventricles. It is defined by the presence of:


Familial DCM contribute about 20–48% of all DCM and can defined by


The prevalence of DCM is 920/100,000 individuals and is common in Afro-Caribbean population. It is the commonest form of cardiomyopathy and is the third most common cause of congestive heart failure. DCM is the commonest indication for heart transplantation. In 30–40% patients, it is transmitted in an autosomal dominant fashion while in others it can be post viral or idiopathic. It can be of ischemic or nonischemic variety with ischemic type being related to atherosclerosis or CAD. The nonischemic variety may present itself secondary to the use of chemotherapeutic agents (doxorubicin and adriamycin), infections (Coxsackie virus, HIV, cytomegalovirus Chagas' disease, trichinosis, toxoplasmosis, Lyme disease, and leptospirosis), drug abuse (alcohol, heroin, cocaine, and methamphetamines), or as peripartum cardiomyopathy.

#### **3.1. Pathophysiology**

**Systolic dysfunction:** This type of dysfunction is mainly seen in dilated cardiomyopathy. The predominant pathophysiology is a global decrease in myocardial contractility, which in turn leads to reduction in left ventricular ejection fraction. In the initial phases, the heart tries to compensate this change by increasing the size of left ventricular cavity which allows for an improvement in stroke volume with an associated improved force of contraction. As the disease progresses, these compensatory mechanisms prove to be inadequate in maintaining

**Diastolic dysfunction:** This is the most common type of dysfunction associated with the cardiomyopathies, occurring in HCM, RCM, and other types of cardiomyopathies. The main pathophysiology is impairment of filling of blood in the left ventricle, which leads to increase in the left ventricular filling pressures. During the beginning of the diastolic phase of a normal cardiac cycle, left ventricle undergoes the phase of Isometric relaxation (which is an energy dependent process) just before the start of left ventricle filling phase. This relaxation continues in the early left ventricular filling phase. The later part of the left ventricular filling is a passive process and depends on the compliance of the left ventricle. Diastolic dysfunction can be because of the impairment of any of the two phases: active relaxation or left ventricular compliance or a combination of the two. Ischaemia mainly affects the phase of isometric relaxation, while intrinsic myocardial pathologies including fibrosis or external restriction due to

The main types of cardiomyopathy that we come across clinically in our day-to-day practice

Some other types of cardiomyopathy are known as "unclassified cardiomyopathy." Another type of cardiomyopathy known as Takotsubo cardiomyopathy has been recently listed and is

Therefore, we focus our attention towards the commonest types of cardiomyopathies in this

Dilated cardiomyopathy (DCM) is defined by cardiac enlargement with impaired systolic

also known as "stress-induced cardiomyopathy," or broken heart syndrome.

function of one or both ventricles. It is defined by the presence of:

the cardiac output, eventually leading to the failure of left heart.

pericardial diseases may lead to a reduction in left ventricular compliance.

are:

chapter.

• Dilated cardiomyopathy

108 Current Topics in Intensive Care Medicine

• Hypertrophic cardiomyopathy

• Arrhythmogenic right ventricular dysplasia

• Restrictive cardiomyopathy

• Peripartum cardiomyopathy

**3. Dilated cardiomyopathy**

Dilated cardiomyopathy presents with a decrease in LV ejection fraction (LVEF) as described earlier, congestive heart failure (CHF) or as ventricular arrhythmias. Initially, the ventricle dilates to increase the force of contraction and stroke volume in order to maintain the cardiac output (Frank-Starling law); however, as the disease progresses, these compensatory mechanisms gradually fail, leading to the ventricular failure and ultimately failure to maintain the cardiac output (CO).

#### **3.2. Signs and symptoms**

The patients of dilated cardiomyopathy present with symptoms like dyspnea, orthopnea, fatigue, weakness, and oedema in the lower extremities. Physical findings are similar to those seen in CHF. Some patients complain of dyspnea on exertion that may look like angina pectoris. Patients may have jugular venous distention, crepitation on auscultation, resting tachycardia, audible s3 and s4 heart sounds, pulmonary oedema, and cardiomegaly. Mitral and/or tricuspid regurgitation may be audible clinically if the ventricular dilation is marked.

The ECG may show ST-T segment abnormalities, atrial fibrillation, intraventricular conduction defects, and PVCs. The echocardiography reveals dilated cardiac chambers, global hypokinesia, low EF/fractional shortening, raised LVEDP, mitral or tricuspid regurgitation and/or mural thrombi. Right-sided cardiac catheterisation using a Swan Ganz Catheter reveals a high pulmonary capillary wedge pressure, high systemic vascular resistance, and a low cardiac output. Additional laboratory tests carried out may reveal raised brain natriuretic peptide levels.

**3.5. Anaesthetic management for non-cardiac surgery**

• minimise any negative inotropic effect of anaesthetic drugs.

• maintain preload despite increased left ventricular end-diastolic pressure.

agents should be administered. Additional doses may not be required.

cally mediated tachycardia, and afterload increases.

us to measure preload and central venous saturation (ScVO<sup>2</sup>

• avoid overdose of medications during induction as the circulation time of drugs is slow.

These patients can become haemodynamically unstable due to the depressant effect of anaesthetic agents, fluid shifts and ongoing blood loss, which add to the already poor myocardial function due the cardiomyopathy. Propofol, thiopentone and inhalational agents cause vasodilation and myocardial depression. Benzodiazepines like midazolam and nitrous oxide may cause cardiovascular depression. Etomidate, ketamine, and narcotics like opioids are the ones that have minimal adverse haemodynamic response. We need to use a balanced anaesthetic technique. Slow induction should be carried out. Response of induction agents may be delayed due to prolonged circulation time, so slow and titrated doses of anaesthetic

Optimal pain management helps to maintain haemodynamic stability. Regional anaesthesia may be a source of excellent postoperative pain relief, reducing the episodes of sympatheti-

*Monitoring*: In addition to basic monitoring, central venous pressure (CVP) monitoring allows

administer inotropes and vasoconstrictors if needed. Direct intra-arterial pressure monitoring enables early identification of haemodynamic alterations by beat-to-beat measurement of BP. Pulmonary artery pressure monitoring is useful in patients undergoing high-risk or emergency surgery or those in whom large fluid shifts are anticipated. The role of noninvasive methods to estimate cardiac output as well as estimate global end-diastolic volumes, the extravascular lung water, and other indices if available are invaluable for assessing cardiac function.

). It provides for an access to

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anticoagulation therapy.

The goals of anaesthesia are to [4]:

• prevent increases in afterload.

• maintain perfusion and control arrhythmias,

• avoid hypotension and tachycardia.

Any major surgeries on these patients can be associated with morbidity and mortality, therefore, requires planning. Optimisation of congestive heart failure (CHF) at least for a week before the planned surgery is advisable. In critically ill or patients undergoing a high-risk procedure or those in which CHF is not appropriately managed, intra-arterial BP line should be inserted preoperatively. Premedication should be tailored according to the patient's requirement and may include short acting anxiolytic and/or sedative. Regional anaesthesia or nerve blocks alone or in combination with general anaesthesia can help us achieve the set goals of anaesthesia with a minimal haemodynamic compromise. However, the ongoing anticoagulation therapy may limit the option of regional anaesthesia. American Society of Regional Anaesthesia (ASRA) guidelines must be strictly followed if the patient is on an
