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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)
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Dilated CM
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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
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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