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Anaesthesiology
Cardiac Anatomy and Physiology
Built from Barash Clinical Anesthesia, 9th Edition
What’s inside
14 sections · 199 slides
Overview
- Scope of this presentation
- The heart as a hydraulic pump
- Key themes of this topic
Gross Anatomy
- Cardiac fibrous skeleton and wall composition
- Ventricular fibre orientation
- Components of the myocardium
- Torsional twist of the left ventricle
- From fibre orientation to ejection
- Interventricular septum and left ventricular motion
- Contraction and emptying of the right and left ventricles
- Structure and function of the right ventricle
- Semilunar valves and the sinuses of Valsalva
- Mitral valve anatomy and motion
- Chordae tendineae, papillary muscles and their failure
- Tricuspid valve and right ventricular landmarks
- Sinoatrial node and atrioventricular insulation
- Normal route of cardiac depolarisation
- His-Purkinje system and pacing dyssynchrony
Coronary Anatomy
- The three coronary arteries and their territories
- Anterior and posterior views of the coronary vessels
- Coronary dominance and regional blood supply
- Three functional compartments of the coronary circulation
- Functional anatomy of the coronary arterial system
- Resistance and exchange vessels of the coronary tree
- Anastomoses and collateral vessels
- Coronary anastomoses and the subendocardial plexus
- Coronary venous drainage
Coronary Physiology
- Poiseuille's law and coronary perfusion pressure
- Resting coronary flow and extravascular compression
- Effect of heart rate on subendocardial perfusion
- Phasic coronary blood flow through the cardiac cycle
- Myocardial energy metabolism
- Oxygen extraction and flow-metabolism coupling
- Matching oxygen supply to demand
- Feed-forward regulation and nitric oxide
- Potassium channels and other vasoactive mediators
- Coronary flow reserve
- Reactive hyperaemia after brief coronary occlusion
- Stenosis severity and hyperaemic response
- Pressure-flow autoregulation
- Autoregulation at two levels of myocardial oxygen demand
- Autonomic control of the coronary circulation
- Net effect of autonomic stimulation
Cardiac Myocyte Anatomy and Function
- The sarcolemma
- Transverse tubules and sarcomere structure
- Sarcoplasmic reticulum and intercalated discs
- Myosin structure
- The myosin molecule
- Myosin ATPase, light chains and titin
- Actin and tropomyosin
- Troponin-tropomyosin complex on actin
- The troponin complex
- Calcium and the myofilaments
- Excitation-contraction coupling
- Conformational change after calcium binding
- Actin filaments and the myosin power stroke
- Reversing the calcium signal
- Phospholamban and inotropic drugs
- The cross-bridge cycle
- The four steps of cross-bridge cycling
- Determinants of shortening velocity
Laplace's Law
- Modelling the ventricle and balancing its forces
- Opposing forces in a theoretical ventricular sphere
- Deriving the Laplace relationship
- Determinants of ventricular wall stress
- Clinical applications of Laplace's law
- Model limitations and transmural stress
The Cardiac Cycle
- Onset of systole and isovolumic contraction
- Ejection and the second heart sound
- Normal ventricular volumes
- Mechanical and electrical events of the cardiac cycle
- Sequence of diastolic events
- Early ventricular filling
- Left atrial and ventricular pressures during filling
- Speed of early filling and diastolic suction
- Diastasis and atrial systole
- The atrial pressure and volume waveforms
Pressure-Volume Diagrams
- The pressure-volume loop
- The steady-state left ventricular pressure-volume diagram
- Reading the loop and the effect of loading
- Two boundaries constrain every beat
- Load-insensitive indices and boundary relations
- Pressure-volume patterns in heart failure
- Effects of reduced contractility and reduced compliance
- Regional pressure-length analysis in ischaemia
- Pressure-segment length diagram in the ischaemic border zone
- The atrial pressure-volume diagram
- What sets the shape of the atrial loop
- Left atrial pressure, volume and flow waveforms
Determinants of Cardiac Performance
- The four determinants of pump performance
- Factors determining diastolic and systolic function
- Structural limits and normal diastolic function
- The force-frequency relationship
- Defining and measuring preload
- Pressure-based estimates of preload and their limits
- Estimating sarcomere length as an index of preload
- Defining afterload
- Indices of Left Ventricular Afterload
- Aortic input impedance and the Windkessel model
- Electrical analogue of the three-element Windkessel model
- Wall stress as a measure of afterload
- Wall stress in pressure-overload and volume-overload hypertrophy
- Ventricular-arterial coupling
- Left ventricular-arterial coupling in the pressure-volume plane
- Effective arterial elastance and vascular resistance
- Four components of afterload in the intact circulation
- Clinical consequences of raised afterload
- The difficulty of measuring contractility
- Indices of Left Ventricular Contractility
- Indices of Left Ventricular Contractility (continued)
- Three families of contractility indices
- Time-varying elastance and end-systolic elastance
- Deriving the end-systolic pressure-volume relation
- Preload recruitable stroke work
- dP/dt max as an isovolumic index
- Ejection fraction and its regional surrogates
- Pitfalls of ejection phase indices
Evaluation of Diastolic Function
- Why diastolic function matters
- Determinants of Left Ventricular Diastolic Function
- Determinants of Left Ventricular Diastolic Function (continued)
- Common Causes of Left Ventricular Diastolic Dysfunction
- Relaxation and the consequences of delaying it
- How delayed relaxation propagates
- The time constant of relaxation
- Limits of the model and what changes tau
- Afterload dependence and isovolumic relaxation time
- Filling indices and grades of diastolic dysfunction
- Evolving patterns of diastolic dysfunction
- The end-diastolic pressure-volume relation
- Stress-strain relations and viscoelasticity
- The pericardium and its pressure-volume relation
- Pericardial versus ventricular pressure-volume relations
- Pericardial restraint, acute and chronic
- Ventricular interdependence
- Respiratory variation in ventricular filling
- Ventilation strategy in tamponade and constriction
Determinants of Atrial Function
- Three mechanical functions of the atrium
- Atrial contractility and afterload
- Atrial response to ventricular failure
- Atrial compliance, the appendage and the pericardium
- Exercise, ageing and the cost of atrial dilation
Pathophysiology of Heart Failure
- Definition and classification of heart failure
- Classification of heart failure by ejection fraction
- Epidemiology of the two phenotypes
- The 50% cut-off and the rise of HFpEF
- Comparison of Major Features of Heart Failure with Reduced versus Preserved Ejection Fraction
- Comparison of Major Features of Heart Failure with Reduced versus Preserved Ejection Fraction (continued)
- Two distinct phenotypes and the inflammatory model
- Features specific to HFrEF
- Medical therapy in the two phenotypes
- Demographics, contractility and outcomes
- Clinical features of HFrEF
- Diagnostic guidelines for HFpEF
- Cardiopulmonary exercise testing in HFpEF
- Exercise haemodynamics and outcome in preserved ejection fraction heart failure
- Functional hallmark of HFrEF
- The compensation cycle in reduced ejection fraction failure
- Neurohormonal activation in HFrEF
- Functional hallmark of HFpEF
- Afterload sensitivity of relaxation in HFpEF
- Inflammation, fibrosis and microvascular disease
- Assessing compliance, and what it does not prove
- Systolic stiffening in HFpEF
- Response to vasodilator therapy
- Ventricular-arterial interaction in the two heart failure phenotypes
- Arterial stiffening in HFpEF
- Ventricular-arterial coupling in the two phenotypes
- Left atrial dilation and dysfunction in HFpEF
- Atrial fibrillation in HFpEF
- Pulmonary hypertension in heart failure
- Right ventricular dysfunction in HFpEF
- Limits on cardiac output reserve in HFpEF
Key Points
- Key points: structure and coronary supply
- Key points: myocyte and mechanics
- Key points: performance and failure
- Key points: the two heart failure phenotypes
References
- References
- References (continued)
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- References (continued)
- References (continued)
- Barash, Cullen, and Stoelting's Clinical Anesthesia, 9th Edition