Electrocardiography and Exercise Stress Testing

• Electrocardiography (ECG) records electrical activity and identifies heart rate, conduction disturbances, myocardial ischaemia, and structural defects.
• Changes may be transient, so comparing readings to previous ECGs is valuable.
• ECGs are helpful in diagnosing coronary artery problems, coronary artery disease, and arrhythmias.
• ST segment elevation or depression suggests ischaemia or infarction.
• Large voltage QRS complexes, downward-sloping ST segments, and T wave inversion might mean chamber hypertrophy.
• Rhythm disturbances like atrial arrhythmias, heart block, and intraventricular septal conduction delays are common in heart failure due to cardiac remodelling. These disturbances can worsen heart failure.

Exercise Stress Testing

• Exercise stress testing is when the heart is stimulated either by exercise on a treadmill or through cycle ergometry, with the patient on an ECG.
• Exercise stress testing may identify myocardial ischaemia and haemodynamic/electrical instability.
• Cardiac stress can be induced with medications if a person cannot perform the exercise test.

Normal ECG Intervals

• Rhythm Strip leads helps determine heart rate and rhythm.
• Positive QRS complexes happen on Leads I and II.
• Tall P waves are signs of right atrial enlargement, while notched P waves can mean left atrial enlargement:
• A normal PR interval is 0.12-0.20 sec. Prolongation suggests impaired atrioventricular nodal conduction
• A short PR interval occurs in Wolff-Parkinson-White syndrome.
• If >0.12 sec, ventricular conduction is abnormal (left or right bundle branch block).
• Large QRS complexes occur in slim young patients and in patients with left ventricular hypertrophy.
• Q waves may mean previous myocardial infarction.
• ST elevation signifies myocardial infarction, pericarditis, or left ventricular aneurysm; ST depression signify ischaemia or infarction.
• T-wave inversion has many causes, including myocardial ischaemia or infarction, and electrolyte disturbances.
• A normal QT interval is <0.44 sec (male) and 0.46 sec (female), corrected for heart rate.
• QT prolongation happens with congenital long QT syndrome, low K, Mg, or Ca, and some drugs.

ECG Conventions

• Depolarisation towards the electrode is positive deflection
• Depolarisation away from electrode is negative deflection
• Sensitivity is at 10mm = 1mV
• Paper speed: 25mm per sec
• Each large (5mm) square = 0.2 sec
• Each small (1 mm) square is 0.04 sec
• Heart rate is 1500/RR interval in mm, such as 300 + number of large squares between beats.

Common Indications for Echocardiography

• Assessment of left ventricular function
• Diagnosis and quantification of severity of valve disease
• Identification of vegetations in endocarditis
• Identification of structural heart disease in atrial fibrillation, cardiomyopathies or congenital heart disease
• Detection of pericardial effusion
• Identification of structural heart disease or intracardiac thrombus in systemic embolism

Chest X-Ray (CXR)

• A chest x-ray helps differentiate between respiratory and cardiac causes of dyspnoea.
• For heart failure, common findings include cardiomegaly, interstitial oedema, pulmonary oedema and pleural effusions.
• Evidence of surgery (eg CABG, valve repair, ICD implantation) is also detected on chest X-rays.

Coronary Angiography

• Coronary angiography checks for the integrity of coronary arteries via catheter and dye injections
• The presence, location, and extent of vessel narrowing are identified on the image.
• Results guide treatment such as revascularisation, PCI, CABG, or medical management.

Echocardiography (Echo)

• Echocardiography provides US images of the cardiac anatomy.
• Transthoracic echo (TTE) uses a transducer external to the chest wall.
• A transoesophageal echo (TOE) is more invasive but gives more details because the ultrasound transducer is passed into a patient's oesophagus
• Echocardiography can provide info on chamber size and shape, blood flow velocities, systolic and diastolic function, contractility, wall motion abnormalities and ejection fraction, valve function, and chamber thrombus.

Cardiac Biomarkers

• Peripheral blood measurements assess myocardial dysfunction & ischaemia.

Brain Natriuretic Peptide

• BNP is a peptide hormone with diuretic properties
• The LV secretes it as a 108-amino acid prohormone; it helps creates active BNP & inactive 76-amino acid N-terminal fragment (NT-proBNP).
• Serum concentrations are elevated in conditions associated with LV systolic dysfunction
• NT-proBNP is usually measured instead of BNP, since it is stabler.
• NT-proBNP measurements can dx LV dysfunction and assess prognosis & response to therapy.

Cardiac Troponins

• Troponin I and troponin T are muscle proteins released during myocyte damage & necrosis.
• Modern assays can detect minor degrees of myocardial damage elevated plasma troponin concentrations are observed in conditions other than acute MI, such as pulmonary embolus, septic shock, & pulmonary oedema.

Myocardial Perfusion Scan (MPS)

• A non-invasive nuclear medicine scan examining myocardial perfusion at rest and stress using a radionuclide.
• Stress scanning is conducted after exercise or using medication
• It identifies severity of coronary artery disease and informs management, such as angiography or coronary artery revascularisation.
• They can also identify patients with recurrent ischaemia following revascularisation

Cardiac Magnetic Resonance Imaging (MRI)

• Cardiac MRI uses magnetic fields and radiofrequency to produce 3D high-resolution images.
• Provides accurate data on cardiac volumes, muscle mass, contractility, tissue scarring and ejection fraction.
• The location and size of myocardial infarction can be defined, and can provide info on bypass grafts.
• Can identify regional wall motion abnormalities (RWMA) and wall dyssynchrony, valve sclerosis, stenosis or regurgitation.
• It provides data about myocardial fibrosis assisting in diagnoses for amyloid cardiomyopathy, myocarditis, and cardiac sarcoid.

Cardiac Computerised Tomography (CT)

• Cardiac CT provides detailed images by identifying anatomical abnormalities such as aneurysms, and valve dysfunction.
• Also provides information about pulmonary vein anatomy related to AF, as well as info about patency of grafts following CABG.
• CT angiography uses contrast dye to enhance information about CAD.
• Calcium scoring with CT checks for the presence, location, and extent of calcified plaque in coronary vasculature.
• The test can give prognostic value and guide investigations/ management.

Cardiac Output

• Cardiac output is the amount of blood pumped out by each ventricle per minute.
• SV (Stroke Volume) x HR (Heart Rate) = CO
• SV is volume of blood ejected by each ventricle per beat; in ml/beat.
• HR (Heart Rate) means beats/minute.
• Cardiac output is in ml/minute, or liters/minute.
• SV = EDV (End Diastolic Volume) - ESV (End Systolic Volume)

Cardiac Index

• Calculated with the formula: CI=CO/BSA= (SV x HR)/ BSA

Cardiac Reserve

• Is the maximum percentage that the cardiac output can increase above normal:
  • 300 to 400 percent
  • 500 to 600 percent or more in trained people
  • Decreases with all types of heart failure

Factors Effective Heart Pump Effectiveness

Preload

• Volume of blood in ventricles at end of diastole.
• Depends on venous return and compliance.

Afterload

• Force needed to eject blood into circulation
• Depends on arterial BP & pulmonary artery pressure.
• Valvular disease increases afterload.

Ejection Fraction

• A measurement used by physicians to assess how well a patient's heart functions.
• "Ejection" refers to the amount of blood pumped out of the heart's main pumping chamber during each heartbeat.
• "Fraction" refers to how even in healthy hearts some blood remains within chamber after heartbeat.
• An ejection fraction is a percentage of the blood within the chamber that is pumped out with every heartbeat
• Normal EF = 55-75%

Definition of Heart Failure

• Heart failure is when the heart as a pump cannot meet the metabolic needs of the tissue for oxygen and substrates, even if venous return heart is normal or increased.
• Heart failure means the heart output isn't able meet the metabolic demands of the body. Underperfusion leads to fluid retention in the body along with swelling and pulmonary oedema.

Risk factors for Heart Failure

• Diabetes
• High blood pressure
• Obesity
• Coronary artery disease
• Valvular heart disease
• Family history of heart failure of heart attacks
• Smoking
• Heavy drinking
• Having a diet high in salt, fat, and cholesterol
• Not getting enough exercise

Keys to understanding the symptoms of heart failure

• All organs (liver, lungs, legs) pump blood back to the heart.
• When the heart fails or weakens- the heart cannot pump blood effectively- causes fluid backs up, increasing the overall pressure in the organs.
• Lung related organ response:
  • Congestion means more effort to breath
  • Fluid starts to escape into the alveoli (pulmonary oedema)
  • Fluid interferes with O2 exchange (hypoxia).
  • Shortness of breath is aggravated
  • Shortness of breath during exertion are early symptoms
  • If progresses, may requires the use of extra pillow when sleeping (orthopnea).

Legs Ankles and Feet heart failure

• Blood from these areas backs up due to the heart unable to pump blood properly
• This causes a increase in fluid within feet and legs (pedal edema) and an increase in weight.

Types (Classifications) of Cardiac Failure

• Based on stage, severity, or compensation:
  • Compensated
  • Decompensated
• Based on side of heart involved:
  • Left heart failure
  • Right heart failure
  • Bilateral heart failure
• Based on cardiac output:
  • Low-output cardiac failure
  • High-output cardiac failure
• Based on duration:
  • Acute heart failure
  • Chronic heart failure
• Based on the type of function affected:
  • Systolic heart failure
  • Diastolic heart failure

Compensated heart failure

• Displayed through the shift of Frank-Starling Curve downwards and to the right
• Shift occurs when the heart is in a failing condition

Heart Failure Etiology

• Systolic Failure- common
  • Hallmark: Reduced left ventricular ejection fraction (<40% EF).
  • Impaired contractile function (e.g., MI)
  • Increased afterload (e.g., hypertension)
  • Cardiomyopathy
  • Mechanical abnormalities (e.g., valve disease)
• Diastolic Failure
  • Ventricles have an impaired ability to relax and fill during diastole, diminishing stroke volume and cardiac output.
  • Diagnosis of pulmonary hypertension, pulmonary congestion, ventricular hypertrophy present
  • Normal ejection fraction.
• Mixed systolic and diastolic failure
  • Found in cases of dilated cardiomyopathy (DCM)
  • Can cause a poor EF (<35%)- and high pulmonary pressures
• Biventricular failure
  • Ventricles may be have a decreased capacity for emptying and filling.

Cardiac Failure based on type of Function affected

Systolic Heart Failure

- Weak contraction of ventricles
- Decreased stroke volume
- Decreased ejection fraction

Diastolic Heart Failure

- Decreased elasticity of myocardium
- Decreased filling during diastole
- An ejection fraction is initially sustained
- Heart failure is caused w/ a preserved ejection fraction

Pathophysiology of Heart Failure

• Heart-related compensatory mechanisms that the body invokes when attempting to fight heart failure:
  • Tachycardia
  • Ventricular dilation
  • Myocardial hypertrophy

NYHA Classification system of Heart Failure:

Class I (Mild)

• No limitation of physical activity.
• Ordinary physical activity does not cause undue fatigue, palpitations, of shortness of breath.

Class II Mild

• Slight limitation of physical activity.
• Comfortable at rest, but ordinary physical activity leads to fatigue, palpitations, or shortness of breath.

Class III (Moderate)

• Marked limitation of physical activity.
• Comfortable at rest, but less than ordinary activity leads to fatigue, palpitations or shortness of breath.

Class IV (Severe)

• Unable to carry out any physical activity without experiencing discomfort.
• Fatigue, palpitations, and shortness of breath symptoms also present at rest.
• If any form of activity is undertaken, discomfort increases.

AHA/ACC staging systems for HF:

Stage A

• Patients at risk of heart failure who have no structural heart disease of symptoms.

Stage B

• Patients with structural heart disease who have not developed signs of symptoms of heart failure.

Stage C

• Patients who have heart disease coupled with prior or current symptoms.

Stage D

• Patients who have refractory heart failure that requires specialized interventions.

Heart Failure Clinical Manifestations:

• Acute and decompensated (ADHF) with pulmonary oedema- potentially life threatening
• Common sign is severe pulmonary oedema, which often proves acutely life-threatening.
• Early symptoms:
• Increased respiration
• Decreased PaO2 (hypoxia.)
• Later signs:
• Tachypnea
• Respiratory acidosis

Acute Decompensated (ADHF) clinical Manifestations:

• Physical findings include Orthopnea, tachypnea, dyspnea and uses of accessory muscles to breath
• May notice cool clammy skin and cyanosis along with S3 Gallup rhythm.
• Cough that includes frothy or blood filled fluid, breath sounds with crackles, wheezes or rhonchi can be present
• Both Hypotension and hypertension along with tachycardia is seen.

Unilateral Heart Failure:

• Left heart Failure:
  • Causes Increased Mean pulmonary filling Pressure,
  • Pulmonary oedema (Rapid)
• Right Heart Failure:
  • Leads to Increased Mean systemic filling pressure
  • And peripheral oedema (Congestive Cardiac Failure (Slow).

General Heart Failure Diagnostics

• To properly diagnose heart failure doctors preform 2D echocardiograms. And if needed preform a Doppler during evaluation.

Initial Evaluation of Heart Failure

• The goal of evaluating heart failure is to Determine the underlying cause of the condition.
• In order to achieve it perform comprehensive history and physical examination of the patient
• Volume status and vital signs also need to be assessed.

Congestive Heart Failure Diagnosis are:

• The use of Chest X-rays (CXR) for, cardiomegaly, Pulmonary oedema, Pleural Effusion, or Kerley b Lines.
• Electrocardiogram (ECG)
• Use of structural or functional ultrasounds of heart.
• Heart Failure Diagnostic Studies*
• For Invasive hemodynamic monitoring the following qualifications must be met:
  • acute HF patients must have persistent symptoms even with empiric adjustment of std therapies.
  • Must show an undeterment fluid status, impaired systemic perfusion, or pulmonary vascular resistance.
  • Have persistent low systolic even with original therapy.
  • Experience worsening renal function.
  • Require vascoactive agents.

Congestive Heart Failure Therapies:

• General Measures that require:
• Management of Underlying Cause.
• Diet Modifications (reduced sodium. with possible fluid restrictions.
• Mild Excercise With adequate rest.
• Smoking Cessation Therapy.
• Adequate Oxygen if needed.
• Wellness Checks with Vaccine Upkeep.
• Medications such as:
• Diuretics
• ACE Inhibitors
• Beta Blockers
• Cardiac Glycosides
• Procedures such as Cardiac Resynchronization(CRT)
• Revascularization- CABG, Valve.

Cardiogenic SHOCK:

• Cardiac shock occurs due to the server Depression the cardiac Cardiac index should be (<2.2 [L/min]/m2) sustained arterial Hypotension (<90 mmHg) pressure
• Early Reperfusion therapy used to reduce incidence
• Occurs in 5-7% of pop.
• Caused by Acute myocardial infraction or Ischemia.
• If has high-grade heart block Systolic blood pressure is reduced (<30 mmHg)