HOCM(hypertrophic obstructive cardiomyopathy)

presentation will give idea about HOCM(hypertrophic obstructive carxdiomyopathy).

1. Hypertrophic cardiomyopathy Dr. Dhaval A. Bhimani

2. Defination Cardiomyopathies are defined by structural and functional abnormalities of the ventricular myocardium that are unexplained by flowlimiting coronary artery disease or abnormal loading conditions. It is genetic myocardial disorder characterized by left and/or right ventricular hypertrophy that is usually, but not always, asymmetric and is associated with microscopic evidence of myocardial fiber disarray and fibrosis. Degree of hypertrophy at any given site can vary substantially and influences clinical manifestations of the disease.

3. Ventricular septal hypertrophy is the most common type of asymmetric hypertrophy, with midventricular, apical, and other types occurring much less frequently. Forms interfering with left ventricular (LV) emptying, termed hypertrophic obstructive cardiomyopathy (HOCM) or (obsolete) idiopathic hypertrophic subaortic stenosis (IHSS), are of surgical importance and are characterized by a variable dynamic obstruction that is usually subaortic and is associated with abnormal systolic anterior motion (SAM) of the anterior leaflet of the mitral valve. Prevalence of HCM in the general population is about 1 in 500 (0.2%) .

4. History Pathologic findings compatible with HOCM were described by two 19th-century French pathologists, Hallopeau and Liouiville and an early 20th-century German pathologist, Schmincke . In 1952, Davies described a family from Cardiff, Wales, with five of nine siblings affected and three dying suddenly who probably had this disease. Disease was first accurately categorized by Teare , a London pathologist, in 1958. Teare described both disproportionate thickening of the ventricular septum compared with the free wall and presence of myocardial fiber disarray in young people who died suddenly.

5. To distinguish it from other cardiomyopathies, Goodwin and colleagues named it hypertrophic obstructive cardiomyopathy, whereas Braunwald and colleagues called it idiopathic hypertrophic subaortic stenosis and Wigle and colleagues, muscular subaortic stenosis. At that time, LV outflow tract obstruction was thought to be distinctive for the disease. That the anterior mitral leaflet contributed to the obstruction was first documented in 1964 by Fix and colleagues and SAM of the mitral valve was subsequently demonstrated angiographically.

6. Etiology Sarcomere protein gene mutations Metabolic disorders Mitochondrial cardiomyopathies Neuromuscular disease Malformation syndromes Infiltrative disease/inflammation Endocrine disorders Drugs

7. In up to 60% of adolescents and adults with HCM, the disease is an autosomal dominant trait caused by mutations in cardiac sarcomere protein genes. Five to ten percent of adult cases are caused by other genetic disorders including inherited metabolic and neuromuscular diseases, chromosome abnormalities and genetic syndromes. Some patients have non-genetic disorders that mimic genetic forms of the disease, for example, senile (TTR) and (AL) amyloidosis

8. TYPES

9. Patghophysiology LVOT Obstruction Diastolic Dysfunction Myocardial Ischemia Autonomic Dysfunction Mitral Regurgitation

10. LVOT Obstuction Obstruction causes an increase in LV systolic pressure, which leads to a complex interplay of abnormalities including prolongation of ventricular relaxation, elevation of LV diastolic pressure, mitral regurgitation, myocardial ischemia, and a decrease in forward cardiac output. Outflow obstruction usually occurs in HCM by virtue of mitral valve SAM and mitral-septal contact. Although the mechanism of the outflow tract gradient in HCM was initially thought to be caused by systolic contraction of the hypertrophied basal ventricular septum encroaching on the LVOT, most recent studies emphasize that during ventricular systole, flow against the abnormally positioned mitral valve apparatus results in drag force on a portion of the mitral valve leaflets, which pushes the leaflets into the outflow tract

11. Patients may have little or no obstruction of the LVOT at rest but can generate large LVOT gradients under conditions such as exercise, the strain phase of the Valsalva maneuver, or during pharmacologic provocation. There is often large spontaneous variation in the severity of the gradient during day-to-day activities or even with food or alcohol intake, exacerbation of symptoms during the postprandial period is common.

12. Diastolic dysfunction Diastolic dysfunction arising from multiple factors is a major pathophysiologic abnormality in HCM that ultimately affects both ventricular relaxation and chamber stiffness. Diffuse myocardial ischemia may further affect both relaxation and chamber stiffness. A compensatory increase in the contribution of late diastolic filling during atrial systole is associated with these alterations. With exercise or any other type of catecholamine stimulation, the decrease in diastolic filling period as well as myocardial ischemia will further lead to severe abnormalities of diastolic filling of the heart, with chest pain and/or an increase in pulmonary venous pressure causing dyspnea.

13. Myocardial Ischemia The myocardial ischemia is frequently unrelated to the atherosclerotic epicardial coronary artery disease (CAD) but is caused by supply– demand mismatch. Patients with HCM of any age have increased oxygen demand caused by the hypertrophy and adverse loading conditions. They also have compromised coronary blood flow to the LV myocardium because of intramural arterioles with thickened walls attributable to medial hypertrophy associated with luminal narrowing.

14. Autonomic Dysfunction During exercise, approximately 25% of patients with HCM have an abnormal blood pressure response defined by either a failure of systolic blood pressure to rise 20 mm Hg or a fall in systolic blood pressure. The presence of this finding is associated with a poorer prognosis. This inability to augment and sustain systolic blood pressure during exercise is caused by either the dynamic LVOT obstruction or systemic vasodilatation during exercise. It is speculated that autonomic dysregulation88 is present in patients with HCM and that the fall in blood pressure associated with bradycardia may be an abnormal reflex response to obstruction

15. Mitral Regurgitation Mitral regurgitation is common in patients with LVOT obstruction and may play a primary role in producing symptoms of dyspnea. The temporal sequence of events of eject-obstruct-leak supports the concept that the mitral regurgitation in most patients is a secondary phenomenon. The mitral regurgitation is usually caused by the distortion of the mitral valve apparatus from the SAM secondary to the LVOT obstruction. Changes in ventricular load and contractility that affect the severity of outflow tract obstruction similarly affect the degree of mitral regurgitation.

16. Diagnosis The diagnosis of HCM rests on the detection of increased LV wall thickness by any imaging modality, but the disease phenotype also includes myocardial fibrosis, morphologic abnormalities of the mitral valve apparatus, abnormal coronary microcirculatory function and electrocardiographic abnormalities. Due to the diverse aetiology of the disease, detection of increased LV wall thickness that is unexplained by loading conditions should prompt a systematic search for its underlying cause.

17. In Adults In an adult, HCM is defined by a wall thickness ≥15 mm in one or more LV myocardial segments—as measured by any imaging technique (echocardiography, cardiac magnetic resonance imaging (CMR) or computed tomography (CT))—that is not explained solely by loading conditions. Genetic and non-genetic disorders can present with lesser degrees of wall thickening (13–14 mm); in these cases, the diagnosis of HCM requires evaluation of other features including family history, non-cardiac symptoms and signs, electrocardiogram (ECG) abnormalities, laboratory tests and multi-modality cardiac imaging.

18. IN Children increased LV wall thickness is defined as the thickness more than 2 standard deviations above the mean for age, sex, or body size (z score >2). These morphometric distinctions are not rigid, however, as patients have now been identified who are "genotype positive/phenotype negative" and may be considered to have subclinical HCM.

19. In Relatives The clinical diagnosis of HCM in first-degree relatives of patients with unequivocal disease (LVH ≥15 mm) is based on the presence of otherwise unexplained increased LV wall thickness ≥13 mm in one or more LV myocardial segments, as measured using any cardiac imaging technique [echocardiography, cardiac magnetic resonance (CMR) or CT]. In families with genetic forms of HCM, mutation carriers can have non-diagnostic morphological abnormalities that are sometimes associated with abnormal ECG findings. In general, the presence of any abnormality [for example, abnormal Doppler myocardial imaging and strain, incomplete systolic anterior motion (SAM) orelongation of the mitral valve leaflet(s) and abnormal papillary muscles], particularly in the presence of an abnormal ECG, increases the probability of disease in relatives.

20. CLINICAL PRESENTATION AND NATURAL HISTORY Many patients with HCM are asymptomatic, but most who come to surgical attention will have limiting symptoms. Typical symptoms caused by obstructive HCM are exertional dyspnea, chest pain (angina), and/ or lightheadedness, especially lightheadedness is associated with rapid change in posture, or syncope. Most common clinical scenario for patients referred for septal myectomy is the development of symptoms in the fourth, fifth, or sixth decade of life.

21. It seems likely, however, that in most patients, the development of symptoms corresponds to the development of subaortic obstruction. Occurrence of AF can also precipitate symptoms and predispose to systemic embolism, which occurs in 6% of patients. AF is found in 30% of older patients with HCM. It is interesting to note that approximately one-third of patients with HCM who are symptomatic will have exacerbation of symptoms, predominantly dyspnea or presyncope, after meals. Postprandial symptom exacerbation is associated with higher resting LVOT gradients and advanced clinical symptoms.

22. In the general population, survival of patients with HCM is similar to survival of individuals without disease, and high mortality in HCM in earlier reports is likely due to excess numbers of high-risk patients included in studies from tertiary referral centers. The importance of LVOT obstruction with regard to late outcome of patients with HCM has been controversial, but there is now substantial evidence that survival of HCM patients with outflow obstruction is reduced in comparison to patients without obstruction.

23. Studies by Maron et al., Au tore and associates, and Elliot and coworkers have demonstrated convincingly a strong correlation between resting outflow gradients and late risk of death. In a longitudinal follow-up of 1,101 patients with HCM, Maron et al. reported that patients with outflow tract obstruction (a basal gradient of at least 30 mmHg) had a risk of death from HCM or symptom progression that was more than four times that observed among patients without obstruction Of note, patients with obstruction and mild symptoms (NYHA class II) were more likely to have progression to severe symptoms or to die from heart failure than asymptomatic patients with cardiomyopathy.

24. Guidelines for investigation ECG- resting and ambulatory. The standard 12-lead ECG can be normal at presentation (6% of patients in referral cohort studies) but generally shows a variable combination of LVH, ST- and T-wave abnormalities, and pathological Q-waves. When interpreted in conjunction with findings on echocardiography and CMR imaging, features that would normally indicate other conditions, such as myocardial ischaemia or infarction, can—with age at diagnosis, inheritance pattern and associated clinical features—suggest an underlying diagnosis or provide clues to the distribution of hypertrophy and myocardial scar.

25. Echocardiography Echocardiography is central to the diagnosis and monitoring of HCM. In most patients, hypertrophy preferentially involves the interventricular septum in the basal LV segments but often extends into the lateral wall, the posterior septum and LV apex. Useful for assessing left ventricular wall thickness . Associated abnormalities of the mitral valve and left ventricular outflow tract. Assessment of latent obstruction . Left atrial enlargement Assessment of diastolic function & Systolic function

26. Variants Stress echocardiography Contrast echocardiography Tranesophageal echocardiography

27. Cardiovascular magnetic resonance imaging Assessment of ventricular morphology and function. Myocardial fibrosis . Late Gadolinium Enhancement and Prognosis. the extent of Lsupport the use of LGE GE on CMR has some utility in predicting cardiovascular mortality, but current data do not in prediction of SCD risk. Differential diagnosis

28. nuclear scintigraphy & CT scan

29. Endomyocardial biopsy

30. Laboratory test First-line laboratory screening should include haematology, glucose, cardiac enzymes (creatine kinase, aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase), renal and liver function tests, pH, electrolytes and uric acid. Following specialist evaluation, additional tests are often required, including measurement of lactate, pyruvate, ammonia, ketones, free fatty acids, carnitine profile, urine organic acids and amino acids.

31. Genetic testing and family screening In the majority of cases, HCM is inherited as an autosomal dominant genetic trait with a 50% risk of transmission to offspring. Some cases are explained by de novo mutations, but apparently sporadic cases can arise because of incomplete penetrance in a parent and, less commonly, autosomalrecessiveinheritance . In patients fulfilling HCM diagnostic criteria, sequencing of sarcomere protein genes identifies a disease-causing mutation in up to 60% of cases.

32. Treatment Medical management of associated symptom and complication, along with LVOT obstruction. Interventional management. Surgical management

33. Medical management Ifasymptomatic , —Recommendations Class I = For patients with HCM, it is recommended that comorbidities that may contribute to cardiovascular disease ( eg , hypertension, diabetes, hyperlipidemia, obesity) be treated in compliance with relevant existing guidelines, (Level of Evidence: C) Class IIa = Low-intensity aerobic exercise is reasonable as part of a healthy lifestyle for patients with HCM. (Level of Evidence: C) Class IIb = The usefulness of beta blockade and calcium channel blockers to alter clinical outcome is not well established for the management of asymptomatic patients with HCM with or without obstruction. (Level of Evidence: C)

34. Class III: Harm 1. Septal reduction therapy should not be performed for asymptomatic adult and pediatric patients with HCM with normal effort tolerance regardless of the severity of obstruction. (Level of Evidence: C) 2. In patients with HCM with resting or provocable outflow tract obstruction, regardless of symptom status, pure vasodilators and high-dose diuretics are potentially harmful. (Level of Evidence: C)

35. Interventional management Involves surgical myectomy and septal alcohol ablation. Dual chamber pacing. Cardiac transplantation.

36. Septal myectomy standard median sternotomy. normothermic cardiopulmonary bypass using a single, two-staged venous cannula and cold blood cardioplegia (initial dose of 1,000 to 1,200 ml) for myocardial protection, Pericardial sutures are used only on the right side to elevate pericardium toward the surgeon and allow the left ventricle to fall posteriorly in the thorax. Oblique aortotomy is made slightly closer to the sinotubular ridge than is usual for aortic valve replacement, and the incision is carried through the midpoint of the noncoronary aortic sinus of Valsalva to a level approximately 1 cm above the valve annulus.

37. A cardiotomy sucker is placed through the aortic valve and used to depress the anterior leaflet of the mitral valve and protect it from injury. A sponge stick is used to depress the right ventricle and rotate the septum posteriorly, orienting the LV outflow anteriorly. A standard No.10 scalpel blade is used for incision in the septum that begins just to the right of the nadir of the right aortic sinus.

38. The area of septal excision is then deepened and lengthened toward the apex of the heart being certain to excise hypertrophied septum beyond endocardial scar. Adequate septal myectomy usually yields 3 to 12 g of muscle. The use of the sponge stick to depress the heart posteriorly will improve exposure of the distal extent of the myectomy. Mitral valve replacement is reserved for patients with intrinsic leaflet abnormalities that cannot be repaired. To confirm complete relief of the LVOT obstruction, we can measure simultaneous aortic and LV pressure by direct needle puncture before and after myectomy.

39. If the resting LVOT gradient is diminished by the effects of anesthesia, premature ventricular beats are induced by stimulating the ventricle to elicit the dynamic gradient produced by the Brockenbrough phenomenon; the postextrasystolic contraction is more forceful due to increased contractility and decreased afterload. The same maneuver is then repeated after myectomy. In some patients, it is necessary to provoke LVOT gradient during surgery with isoproterenol. Intraoperative TEE can identify residual MR, SAM, and any septal defects created by excision of septal muscle.

40. Severe MR in patients with obstructive HCM is not an indication for mitral valve replacement. Indeed, MR due to SAM is always relieved when outflow tract obstruction is corrected. Unroofing of coronary artery bridging is performed in selected cases, particularly in young patients and those who have angina preoperatively

41. Complication Complete heart block Iatrogenic ventricular perforation Complete left bundle branch(most common after septectomy) Alcohol septal ablation causes right bundle branch block in up to 60% of patients, and in patients who have had previous alcohol septa! ablation, the risk of pacemaker insertion following surgical myectomy was 36% compared with 3% for those without prior intervention. Aortic valve regurgitation

42. Special consideration There is general consensus that an ICD is strongly warranted for secondary prevention of SCD in patients with prior cardiac arrest or sustained and spontaneously occurring ventricular tachycardia, and should be considered for primary prevention in patients with multiple clinical risk factors and in selected patients with a single major risk factor such as a history of SCD in a close relative. For patients who need an ICD and are referred for septal myectomy, we can prefer to delay device implantation until the third or fourth day postoperatively and avoid the potential for lead dislocation if the ICD is placed immediately preoperatively.

43. Cardioverter-Defibrillator Patients with HOCM and unexplained syncope, cardiac arrest, and ventricular tachycardia or fibrillation should be considered for implantation of a cardioverter-defibrillator in combination with myectomy or other surgical procedures. Implantation may be indicated in some patients with nonobstructive HCM who have a history of cardiac arrest or unexplained syncope and in whom physiologic testing is positive

44. Dual-Chamber Pacing Dual-chamber (DDD) pacing decreases the subaortic pressure gradient and relieves associated symptoms in some patients with HOCM. sociated symptoms in some patients with HOCM. The mechanism by which the gradient is decreased is uncertain but may be related to decreased septal motion, which results in increased LV outflow tract area and reduced SAM of the anterior mitral leaflet, late activation of the basal septum, or decreased LV contractility. Not all patients respond favorably to pacing. In the study by Topilski and colleagues, positive results were attributed to periodic assessment and optimization of pacemaker function. DDD pacing may be of particular value in the elderly and other patients who are not candidates for myectomy or septal ablation

45. Cardiac Transplantation Cardiac transplantation should be considered for suitable candidates with HOCM who have not responded to maximal medical and surgical therapy. These patients usually have intractable symptoms of heart failure associated with dilated ventricular cavities

46. Left Ventricular–Aortic Conduit A valved conduit from the apex of the LV to the thoracic or abdominal aorta has been inserted in patients with HOCM. This procedure should be used only when other methods of surgical treatment are infeasible.

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