**4.3. Treatment**

The varied clinical profile of HCM makes it difficult to establish some precise guidelines for the treatment of this condition. The treatment plan should be titrated according to individual patient requirements. However, it is prudent to mention that the patients who are at high risk for sudden death should receive aggressive treatment.

Medical management: Pharmacotherapy is aimed at reducing LVOTO, improving diastolic filling, and possibly decreasing myocardial ischaemia. A variety of medical therapies have been used in these patients with the aim of altering the natural history. These include β-blockers, Ca2+ channel antagonists (verapamil or diltiazem), and disopyramide regimens, all of which seem to be effective as compared to no treatment in HCM patients. Most of these drugs used help HCM patients to improve their symptoms by reducing or eliminating the LVOT pressure gradient. These medications also reduce LVOTO during exercise by blunting the sympathetic response and are thus useful in treating the symptoms and attenuating the risk of sudden cardiac arrest. Atrial fibrillation often develops in these patients. It is associated with an increased risk of thromboembolism and congestive heart failure. Amiodarone is the most effective drug for prevention of repeated episodes of atrial fibrillation in these patients. Long-term anticoagulation is indicated in the patients with recurrent or chronic atrial fibrillation to prevent thromboembolic episode reducing the mortality and morbidity associated with it.

More recently, perhexiline, which augments myocyte energy supply, has been shown to improve diastolic dysfunction and symptomatology, but detailed studies are yet to follow.

**Alcohol septal ablation** [5]: Ethanol can be infused into the septal branches of the left anterior descending coronary artery and induce a targeted septal myocardial infarction (MI). Alcohol septal ablation is associated with some serious hazards, most common being the right bundle branch block, which has a post-procedural incidence of approximately 50%. Other complications include remote MI due to collateral circulation or an ethanol injection into the incorrect coronary, coronary dissection, ventricular septal rupture, heart failure, and heart block.

**Surgical management:** The American and European Colleges of Cardiology recommend myectomy in patients with:


Some patients may be candidates for implantable cardioverter-defibrillator (ICD) implantation while as principal surgical option is surgical myomectomy.

**Prognosis:** The overall mortality rate of HCM is 1% per annum. However, some patients at higher risk of sudden death as described before have an annual mortality rate of 5%.

**Patients undergoing non-cardiac surgery:** Most of the time, the patients with HCM are asymptomatic when they show up in the PAC clinic for elective surgeries. In the absence of signs and symptoms, the ECG findings may suggest that the patient has underlying HCM.

Initial patient evaluation should be aimed at determining the disease severity by assessing functional status of the patient, personal and family cardiac history, the presence or absence of cardiac and respiratory symptoms, history of rhythm disturbances, current medications, and previous strokes, or congestive heart failure history. During physical examination, all murmurs should be evaluated for dynamic changes with rest and exertion, and patients with murmurs that do not fulfil the criteria of a benign murmur should undergo an echocardiographic examination before surgery. Patients should be instructed to continue their rate controlling medications and maintain proper hydration preoperatively. Moreover, the presence of an automatic ICD and if it has been recently checked should be determined.

**Preoperative management:** A lot of patients with HCM may experience perioperative cardiac events like MI, congestive heart failure, severe hypotension, and supraventricular and ventricular tachydysrhythmias. Therefore, we need to focus on understanding the basic pathophysiology of the events and adjust our anaesthetic plans according to the patient needs.

In patients with HCM, preoperative administration of anti-anxiety medications may help to reduce anxiety and prevent the activation of anxiety-induced sympathetic response. Adequate preoperative intravenous fluid administration may help in preventing LVOTO and minimise the effect of positive pressure ventilation on central blood volume.

For patients who have an ICD in situ, the device should be turned off just before the surgery and an external defibrillator should be readily available and the ICD should be positively reactivated in the recovery room.

The anaesthetic goals are [4]:

presence of LVOTO by demonstrating turbulent flow across the aortic valve. Pressure gradients across the LVOT can be measured. Echocardiography is useful in evaluating diastolic function

Invasive measures like cardiac catheterisation allow direct measurement of the increased left ventricular end-diastolic pressure and the pressure gradient between the left ventricle and

The definitive diagnosis of HCM can be made by an endomyocardial biopsy and DNA analysis, but these diagnostic modalities are usually reserved for patients in whom the diagnosis

The varied clinical profile of HCM makes it difficult to establish some precise guidelines for the treatment of this condition. The treatment plan should be titrated according to individual patient requirements. However, it is prudent to mention that the patients who are at high risk

Medical management: Pharmacotherapy is aimed at reducing LVOTO, improving diastolic filling, and possibly decreasing myocardial ischaemia. A variety of medical therapies have been used in these patients with the aim of altering the natural history. These include β-blockers, Ca2+ channel antagonists (verapamil or diltiazem), and disopyramide regimens, all of which seem to be effective as compared to no treatment in HCM patients. Most of these drugs used help HCM patients to improve their symptoms by reducing or eliminating the LVOT pressure gradient. These medications also reduce LVOTO during exercise by blunting the sympathetic response and are thus useful in treating the symptoms and attenuating the risk of sudden cardiac arrest. Atrial fibrillation often develops in these patients. It is associated with an increased risk of thromboembolism and congestive heart failure. Amiodarone is the most effective drug for prevention of repeated episodes of atrial fibrillation in these patients. Long-term anticoagulation is indicated in the patients with recurrent or chronic atrial fibrillation to prevent thromboembolic episode reducing the mortality and morbidity associated

More recently, perhexiline, which augments myocyte energy supply, has been shown to improve diastolic dysfunction and symptomatology, but detailed studies are yet to follow.

**Alcohol septal ablation** [5]: Ethanol can be infused into the septal branches of the left anterior descending coronary artery and induce a targeted septal myocardial infarction (MI). Alcohol septal ablation is associated with some serious hazards, most common being the right bundle branch block, which has a post-procedural incidence of approximately 50%. Other complications include remote MI due to collateral circulation or an ethanol injection into the incorrect coronary, coronary dissection, ventricular septal rupture, heart failure, and heart block.

**Surgical management:** The American and European Colleges of Cardiology recommend

of the heart.

114 Current Topics in Intensive Care Medicine

the aorta.

**4.3. Treatment**

with it.

myectomy in patients with:

cannot be established by non-invasive means.

for sudden death should receive aggressive treatment.


Tachycardia, arrythmias, and decreases in afterload will exacerbate LVOTO and may cause haemodynamic deterioration. In addition to this, increases in contractility (chronotropy) and decreases in preload will accentuate LVOTO. Therefore, the principle of treatment for hypotension is volume expansion (including increasing preload in the Trendelenburg position) and use of drugs that increase systemic vascular resistance without a positive inotropic or chronotropic response (e.g. phenylephrine and vasopressin). Sympathetic response secondary to patient anxiety, intubation process, and surgical site incision and acute changes in preload, afterload, and contractility secondary to the pharmacological effects of anaesthetic agents, blood loss during surgery, and postoperative pain can precipitate haemodynamic collapse. DC cardioversion may be necessary in case of sudden onset of atrial fibrillation that is haemodynamically unstable.

cardiomyopathy is prevalent in tropical regions of the world, where incidence of endomyocardial fibrosis is high. In non-tropical regions, idiopathic fibrosis is the common cause and is associated with increasing age. Other rare causes of RCM include amyloidosis, haemochro-

Current Perspectives on Cardiomyopathies http://dx.doi.org/10.5772/intechopen.79529 117

RCM is characterised by contracted stiff ventricles with progressive impairment of diastolic filling, leading to the haemodynamic problem of a low preload but high ventricular filling pressure. This pattern of diastolic dysfunction leads to dilation of the atria and elevation of mean atrial pressures, resulting in biventricular "backward heart failure" manifesting itself as pulmonary venous congestion leading to dyspnea as well as systemic venous pressure elevation resulting in peripheral oedema. Systolic function is preserved in most cases. However, in spite of intact systolic function, the restrictive pathology on true ventricular preload limit the stroke volume, resulting in low cardiac output and ultimately hypoperfu-

RCM presents with signs and symptoms of both right and left heart failure. Patients complain of exercise intolerance because of diminished cardiac output. Patients often have a low volume pulse, an audible third heart sound, regurgitant murmurs, and a raised JVP with rapid X and Y descent that increases or fails to decrease on inspiration. Low blood pressures are often seen, complicating heart failure management. Pulmonary oedema is uncommon. Syncope occurs occasionally, often exertional, reflecting the limited ability of the heart to increase diastolic filling and is an ominous sign. Syncope may also be aggravated by antihypertensive medications. Concomitant autonomic neuropathy can precipitate orthostatic hypotension as

Arrhythmias and conduction disturbances are frequent. Less frequent cardiac manifestations include dynamic LV outflow obstruction, often confused with hypertrophic cardiomyopathy; cardiac ischaemia caused by amyloid deposition in intramural coronary arteries; and intracardiac thrombosis caused by atrial wall standstill, with a risk for systemic embolisation.

The ECG may demonstrate conduction abnormalities. The chest X-ray shows signs of pulmonary congestion and/or pleural effusion, but cardiomegaly is absent. Echocardiographybased two-dimensional and Doppler are essential for determining diastolic dysfunction and for distinguishing patients with RCM from patients with restrictive physiology because of constrictive pericarditis. Echocardiography may also provide information to suggest a specific diagnosis such as the presence of regional wall motion abnormalities in a non-coronary distribution and aneurysms, which would raise the suspicion for cardiac sarcoidosis (CS). Cardiac magnetic resonance (CMR) imaging can aid in the diagnostic process, but the use should be determined on an individual basis. Endomyocardial biopsy (EMB) may be helpful for establishing a diagnosis in some cases. Ultimately, diagnosis of any of the RCMs relies on

matosis, sarcoidosis, and eosinophilic endocarditis.

can volume contraction from nephrotic syndrome.

a constellation of clinical, laboratory, and imaging findings.

**5.1. Pathophysiology**

sion of the tissues.

**5.2. Signs and symptoms**

Although both general and neuraxial anaesthesia can be used, it is important to have a clear understanding of the haemodynamic changes associated with each option. Depending on the route of the anaesthetic drugs chosen, close monitoring and titration of the medications affecting heart rate, preload, afterload, contractility of myocardium, and sympathetic activity are important. Neuraxial techniques may also be considered. In general, a slow controlled titration of medication via an epidural is preferred over a single dose spinal anaesthesia with the aim of maintaining preload and afterload and avoiding sympathetic stimulation. Regional anaesthesia can be an invaluable tool to manage postoperative pain and in turn prevent the activation of sympathetic response in these patients.

In addition to the standard American Society of Anaesthesiologists monitoring requirements, an intra-arterial catheter and/or non-invasive pulse plethysmographic variability (PPV) index monitor and central venous pressure (CVP) monitoring may be considered. The overall haemodynamic goals include maintaining the mean arterial blood pressure at >65–70 mm Hg to maintain coronary perfusion pressure to the subendocardium in the hypertrophied heart. The most useful monitoring tool for patients undergoing high-risk surgery is TEE. TEE can determine whether haemodynamic alterations are caused by hypovolemia, increased LVOTO or SAM, or LV systolic dysfunction.

**Postoperative management:** Patient with HCM should be continuously monitored in the postoperative room. All factors that activate a sympathetic response like pain, hypothermia, shivering, anxiety, hypoxia, and hypercarbia should be immediately addressed. The maintenance of euvolemia and prompt treatment of hypotension is very important.
