CardiomyopathiesDr Tarun Bhatnagar

Consultant Cardiac Anaesthesiologist dr.tarunbhatnagar@yahoo.co.in

WHO in 1995 defined Cardiomyopathies as diseases of myocardium associated with cardiac dysfunction

TypesDilated Cardiomyopathy(DCM)Hypertrophic Cardiomyopathy(HCM) Restrictive Cardiomyopathy(RCM) Arrythmogenic RVCardiomyopathy(ARVC)

Introduction

DCM is most common of all CMs(60%) Aetiology -Idiopathic (50%)

-Myocarditis (9%)-Ischemic (7%)-Others-Viral, Peripartum, Substance abuse etc

Morphologically Enlargement of RV & LV cavities without an increase in ventricular septal or free wall thickness → spherical shape & dilatation of heart → Displacement of papillary muscles → Regurgitant lesions despite valve leaflets being normal

Dilated Cardiomyopathy(DCM)

5 of 48

Dilated CM

Medslides.com

Microscopically –Patchy & diffuse loss of tissue with interstistial fibrosis & scarring

Systolic Dysfunction>>> Diastolic dysfunction

SV is initially maintained by ↑↑ EDV With disease progression→Marked LV

dilatation with normal or thin wall →↑ Wall stress + Valvular Regurgitation →Overt Circulatory Failure

Pathophysiology

Symptoms-Typically pts c/o months of fatigue, weakness, reduced exercise tolerance due to CHF-May also present as a Stroke, Arrythmia or Sudden Death

Physical Signs-Tachycardia -pulsus alternans-Jugular venous distension-Murmurs of AV valve regurgitation-Gallop heart sounds

Clinical Features

CXR- Cardiomegaly , Pulmonary venous congestion ECG- Normal or low QRS voltage , abn axis, non

specific ST seg abnormalities, LV hypertrophy, conduction defects, AF, Non sustained VT

2D Echo Coronary Angiography

-usually normal coronaries -coronary vasodilatation is impaired by ↑ LV filling pressures-distinguishes b/w Ischemic & Idiopathic DCM

Endomyocardial Biopsyrarely valuable to identify the aetiology

Diagnosis

2D Echo

Aim of treatment-Manage the symptoms -Reduce the progression of disease-Prevent Complications

Mainstay of Therapy Vasodilators + Digoxin +

Diuretics

Management

ACE Inhibitors -Indicated for all patients- Reduce symptoms & improve effort tolerance- Suppress ventricular remodelling & endothelial dysfunction-Reduce CV mortality

Milrinone-Selective PDE-3 inhibitor -may improve quality of life but doesn’t affect mortality-rarely adm in chronic situations

Vasodilators (afterload reducing drugs)

Spironolactoneused along with ACE Inhibitors has shown to reduce mortality by 30% in a large double blind randomized trial

Digoxinclinically beneficial as reaffirmed by two large trials in adults

β Blockersuntill recently contraindicated but recent studies show that they not only provide symptomatic improvement but substantial reduction in sudden death in NYHA class II & III HF pts

Amiodarone-High grade ventricular arrythmias (Sustained VT or VF) are common in DCM→↑ risk of SCD-Preferred antiarrythmic agent as it has least negative inotropic effect & proarrythmogenic potential -Implantable Defibrillators are used for refractory arrythmias

Anticoagulants-indicated for pts with moderate ventricular dilatation+mod-severe systolic dysfunction-H/O stroke , AF or evidence of Intracardiac thrombus

Dual Chamber Pacing Cardiomyoplasty LV Assist Devices

improved pts sufficiently to avoid transplant or enable later transplant

Cardiac Transplantationhas substantially prolonged survival in DCM pts with 5 yr survival rate of 78%

Pts refractory to Pharmacological therapy for CHF

Cardiac procedures which DCM pts undergo-Correction of AV valve insufficiency-Placement of ICD device -LV Assist device placement-Allograft Transplantation

Goals of Anaesthetic Mx- Reduction of afterload-Optimizing preload-Minimize myocardial depression

DCM pts are extremely sensitive to cardiac depressant anaesthetic drugs

Anaesthetic Considerations

Fentanyl-(30u/kg )provides excellent anaesthesia & hemodynamics in pts with EF<0.3

Remifentanyl- assoc with severe hypotension & bradycardia ,therefore unsuitable in low EF pts

Etomidate-least effect on cardiac contractility in pts undergoing cardiac transplant

Ketamine-excellent choice in combination with fentanyl for induction in pts with severe myocardial depression

Propofol-causes CV depression due to inhibition of sympathomimetic activity & vasodilatation

Volatile agents-Desflurane with lowest BG partition coefficient may allow some benefit for rapid induction, rapid recovery from anaesthesia & early extubation

Anaesthetic Agents

Invasive hemodynamic monitoring -Mandatory in pts with DCM undergoing

surgery-Physical s/s may not accurately reflect physiological parameters-Pts with Implanted defibrillators have severely depressed cardiac function but are routinely managed without a PAC

Hemodynamic Instability-managed by low dose of inotrope & vasodilator

Afterload reduction-improves regional & global indices of ventricular relaxation & EF during anaesthesia when myocardial depression may be significant-it also reduces valvular regurgitation & volumes

Patients on Amiodarone on long term basiscan interact with anaesthetic agents & further reduce contractility & conduction-requires careful titration

Arrythmogenic factors –Hypokalemia, Hypomagnesemia, & Sympathatic activation should be monitored & corrected

Hypertrophic Obstructive Cardiomyopathy(HOCM) Idiopathic Hypertrophic subaortic stenosis(IHSS)Assymetric Septal Hypertrophy

M/c genetic cardiac disease Prevalance in adults-0.2%

Primary myocardial abnormality with sarcomeric disarray & assymetric LV hypertrophy

Hypertrophic Cardiomyopathy (HCM)

Massive left ventricular hypertrophy, mainly confined to the septum

Histopathology showing significant myofiber disarray and interstitial fibrosis

Genetic Basis of HCM Causes: Inherited,

acquired, unknown Autosomal

dominant inheritance pattern

>450 mutations in 13 cardiac sarcomere & myofilament-related genes identified

?? Role for environmental factors

Hypertrophic cardiomyopathy: variantsHypertrophic cardiomyopathy morphology exhibits heterogeneity. The mostcommon variant is assymetric septal hypertrophy involving the entire septum

Subaortic Obstruction Diastolic Dysfunction Myocardial Ischemia Mitral Regurgitation Arrythmias

Pathophysiology

Cause -Assymetrical Septal Myocardial Hypertrophy Unlike Aortic stenosis hypertrophy begets pressure

gradient , not the other way around Wide spectrum of severity of obstruction ch by

Variability- absent to critically severeDynamic nature - depends on contractility & loading conditions Timing - begins early & peaks variablyLocation -subaortic

Pathophysiology Subaortic Obstruction

Subaortic ObstructionCause-Hypertrophic septum encroaching on the systolic outflow tractBounded-Anteriorly by IVS & Posteriorly by AMLEffect-Systolic anterior motion(SAM) of AML → accentuating obstructionMechanism of SAMThickened IVS→Restricted LVOT → ejection of blood at a higher velocity closer to the AML → Drawing of AML closure towards the hypertrophied septum due to the venturi effect during LV systole→ Dynamic LVOT obstruction

Pathophysiology

Factors aggravating SAM & producing Dynamic Obstruction-

-↑ Contractility -↓ Afterload (Aortic outflow resistance) -↓ Preload (End diastolic volume)

Therapeutically Myocardial depression, Vasoconstriction & Volume overloading should minimize obstruction & augment forward flow

LVOT gradient ≥ 30mmHg assoc with physiologic & prognostic importance

LVOTO is assoc with ↑ wall stress, myocardial ischemia, cell death & eventually fibrosis→VT /VF

Dynamic LVOTO may also occur in Cardiac tamponade or Acute MI

Hypertrophied & disorganized myocytes with ↑CoT

Impaired relaxation+ ↑ Chamber stiffness

Diastolic Dysfunction→↓ rate of rapid ventricular filling ↑ atrial systolic filling

↑ Filling pressures & pulmonary congestion

Pathophysiology Diastolic Dysfunction

Pathophysiology of HCM Myocardial Ischemia

◦ Often occurs without atherosclerotic coronary artery disease

◦ Postulated mechanisms Abnormally small and partially obliterated intramural

coronary arteries as a result of hypertrophy Inadequate number of capillaries for the degree of LV

mass

Dyspnea on exertion (90%) Angina (70-80%) Syncope (20%) Sudden cardiac death

Clinical Presentation

ECG-↑ QRS voltage, ST-T changes, Axis deviation, LV Hypertrophy +strain pattern

CXR-Lt atrial enlargement or normal Echo Invasive Cardiac Cath- indicated for

suspected CAD or Severe mitral valve disease- shows LV pressure gradient,↓ ventricular volume, ↑ LVEDP

Diagnosis

(A)Dynamic LVOTO with SAM are shown in this parasternal long-axis (PLAX) view

(B)Suboptimal mitral leaflet coaptation accompanies SAM and is typically accompanied by a posteriorly directed MR jet. Note the turbulence created in within the LVOT

Pharmacological Surgical Non Surgical Alternatives Implantable Cardioverter Defibrillator(ICD) Cardiac Transplantation

Management

β Blockers- mainstay of therapy relieves symptoms of exercise intolerance & dyspnoea assoc with CHF by- negative inotropic effect -HR reduction -lower myocardial O2 demand - longer diastolic filling times

CCB-Verapamil is indicated if β Blockers not tolerated or ineffective

-it improves diastolc function & ventricular relaxation causing improved filling decreased obstructive features in 50% pts-CCBs with strong vasodilatory effect are C/I in pts with obstructive symptoms

Disopyramide- has negative inotropic & vasoconstrictive effects-most effective agent to reduce LVOTO , gradient & relieving the symptoms

Pharmacological

IndicationsSubaortic gradients≥ 50mmHg frequently assoc with CHF & are refractory to medication

Septal Myotomy +Partial Mymectomy thru a transaortic approach relieves the obstruction, reduces the LVOTO gradient, SAM & MR

Complications –CHB or septal perforation (0-2%) Mortality rate-1to 3% Intraop guidance & Evaluation of surgical result

by an experienced echocardiographer are essential for the success of the procedure

Surgical Correction

Surgical Septal Myectomy

Nishimura RA et al. NEJM. 2004. 350(13):1320.

Septal Ablation with Ethanol-Non surgical septal reduction therapy-2-5 ml of Ethanol is adm thru an angioplasty balloon catheter lumen to the first major septal perforator of the LAD - reduce LVOT grad in 85-90% pts immediately-Further ↓in grad & sympt improvement seen over next 3-6mths- Permanent heart blocks ( 5-10%)

Dual Chamber or AV Sequential Pacing(DDD)-Exact mechanism unkn-Possible mech: Excitation of the septum of LV contracts it away from apposing wall which may reduce the LVOT gradient-now rarely recommended since symptoms actually worsen despite gradient reductions

Non Sugical alternatives

Alcohol Septal Ablation

.

Alcohol Septal Ablation

Before After

HCM is the most common cause of SCD in otherwise healthy young individuals

VT /VF is primarily responsible for SCD Identification of High Risk Individuals is very important

-Pts < 30yrs at the time of diagnosis-Prior cardiac arrest-Symptomatic VT on Holter monitor-Family H/O SCD or Syncope

The only effective modality to prevent SCD in HCM pts is an ICD

Pharmacological therapy for prevention of SCD in these pts has been abandoned

Implanatable Cardioverter Defibrillator (ICD)

Aim of Anaesthetic management - Avoid aggravating the subaortic gradient

Anaesthetic goals for a patient with HCM are same for cardiac or non cardiac surgery :

Preload- Increased Afterload-Increased Contractility-Depressed Avoid tachycardia, Inotropes, Vasodilators

To achieve these, -Maintain adequate volume status-Avoid direct or reflex increase in HR or contractility by heavy premedication & maintaining adequate anaesthesia & analgesia-Continuation of β blockers or CCBs upto the day of sx & restart immediately after sx -Use of vasoconstrictors to maintain MAP or CPP instead of Inotropes

Anaesthetic Considerations

Induction- IV Narcotics/Propofol in carefully titrated doses can be used

Maintenance-Halothane is advantageous because of its negative inotropic & chronotropic effect

Intraop Hypotension- Trendelenburg position, Volume replacement, & Vasoconstrictors

Arrythmia management-Asymptomatic Nonsustained VT-benign-Pts with ICD device needs to be suspended in presence of Electrocautery-Chronic AF :B Blocker+Verapamil-Amiodarone is effectve in restoring NSR in pts with HCM

Monitoring ECG-closely monitor for arrythmiasCVP/PAC/TEE- for volume status, Hemodynamic monitoring

Avoid Inotropes, B agonists & Calcium

Anaesthetic Considerations

46 of 48

HCM vs. Athletic Heart

HCM Can be asymmetric Wall thickness: > 15 mm LA: > 40 mm LVEDD : < 45 mm Diastolic function: always

abnormal

Athletic heart

Concentric & regresses with deconditioning

< 15 mm < 40 mm > 45 mm Normal Occurs in about 2% of elite althetes –

typical sports, rowing, cycling, canoeing

WHO in 1995 defined RCM as restrictive filling & reduced diastolic volume of either or both ventricles with normal or near normal systolic function & wall thickness

Classification of RCM Myocardial

Nonifiltrative – Idiopathic, Familial, HCM, DiabeticInfiltrative- Amyloidosis, SarcoidosisStorage diseases- Haemochromatosis, Glycogen storage diseases

Endomyocardial Endomyocardial fibrosisCarcinoidRadiationDrug Induced –Serotonin, Methysergide, Busulfan, Ergotamine

Restrictive Cardiomyopathy

Hallmark –Abnormal Diastolic Dysfunction Impaired ventricular relaxation & abnormal Compliance

causes rapid filling in early diastole & impeded filling during rest of diastole

Characteristic -Ventricular diast waveform of Dip & Plateau (Square root sign) -RA pressure waveform-M or W shaped due to rapid y descent

Pressure in the ventricle rises precipitously in response to small volume

Both ventricles appear thick with small cavities in contrast to corresponding dilated atria

Lt sided Pulmonary venous pressure >Rt sided venous pressure by 5mmHg

PASP↑↑ upto 50mmHg Either RVF or LVF or BVF

Pathophysiology

Restrictive Pattern“Square-Root Sign” or “Dip-and-Plateau”

Symptoms of Rt &/or Lt heart failure Kussmaul’s sign- ↑ JVP during inspiration Pulsus paradoxus- infrquent CXR- pulmonary congestion, small heart size ECG- BBBs, low voltage, QR or QS complexes 2D Echo

Clinical Features/Diagnosis

2D ECHO

Characteristic

RCM Constrictive Pericarditis

Jugular venous waveform

↑ with more rapid y descent

↑ with less rapid y descent

Paradoxical Pulse

Rare Frequent

Auscultation Late S3, low pitched, S4 occ

Early S3,highpitched, No S4

Heart size N to ↑ N to ↑

MR/TR Frequently present Frequently absent

CXR Pericardial calcification rare

common

ECG Conduction abn common

rare

ECHO Major enlargmt of Atria Slight enlargmt of Atria

LAP>RAPRVP waveform

RVEDP/LVEDP

AlwaysSquare root pattern, Dip & Plateau less prominentLVEDP>RVEDP by 5mmHg

AbsentSquare root pattern

↑ ↑ & Equal

CT/MRI Rarely thickened pericardium

Thickened pericardium>3mm

Endomycardial Biopsy

Non specific abn Normal

IdiopathicDiuretics-To relieve congestionB-blockers, Amiodarne, CCBs- Control of HR Long term anticoagulationCCBs, ACEI- To enhance myocardial relaxationDual Chamber Pacing- AV blockCardiac Transplantation- Refractory Heart Failure

Amyloidosis- Melphelan, prednisone, H+L transplant Haemochromatosis- Phlebotomy, Desferrioxamine Carcinoid- Somatostatin analogs, Valvuloplasty/Valve

replacement Sarcoidosis –Steroids , Pacing, ICD, Transplantation EMF with eosinophilic cardiomyopathy:

Endocardiectomy +TV/MV replacement

Management Depends on the Aetiology

Adults with RCM present for CT or MVR/TVR Diastolic dysfunction + filling abn- Poor CO & systemic

perfusion Aggresive preop diuretic tharapy- Severe hypovolemia Pulmonary Congestion leads to ↑ Airway pressures Induction-Avoid drugs causing ↓ venous return, bradycardia &

myocardial depressionFentanyl (30u/kg), Sufentanyl, Etomidate , Ketamine provide stable hemodynamics for inductionRemifentanil, Propofol –unsuitable

Invasive hemodynamic monitoring & TEE Inotropic support to maintain CO Diuretics / Vasodilators may be deleterious because

higher filling pressures are needed to maintain the CO

Anaesthetic Considerations

Progressive replacement of RV myocardium with fat & fibrous tissue creating an excellent envt of fatal arrythmias

Typical involves regional RV→Global RV→Partial LV involvement with sparing of septum

Familial Inheritance, adolescents Presentation

-Onset of Arrythmias from RV range fromVPCs-VF -SCD 75% due to VT/VF in sports related exercise -CHF 25%-Progressive RV & LV Dysfunction

Diagnosis- Genetics, ECG, Serial Echo, EM BiopsyECG-Inverted T waves (Rt precordial leads) QRS >110ms Extrasystoles +LBBB

Arrythmogenic RV Cardiomyopathy (ARVC)

Any Family H/O SCD or syncope at an early age must alert the anaesthesiologist

Arrythmias are more likely in the periop period Intraop /Postop Avoid any noxious stimuli

Light anaesthesiaInadequate analgesiaHypercarbiaHypovolemiaAcidosis-detrimental due to its effect on arrythmia generation & myocardial function

GA perse doesn’t appear to be arrythmogenic Propofol , Midazolam, fentanyl-successfully used Amiodarone- Antiarrythmic of choice during

Anaesthesia

Anaesthetic Considerations