1 Cardiovascular Testing J.B. Handler, M.D. Physician Assistant Program University of New England

2 Abbreviations PCI- percutaneous coronary intervention CHD- coronary heart disease CABG- coronary artery bypass surgery Tc- technetium CO- cardiac output SVR- systemic vascular resistance

3 Ambulatory Monitoring Arrhythmia Detection Evaluation of Syncope Evaluation of symptoms suggestive of arrhythmia Identifying patients with heart disease at risk for sudden death Evaluation of anti-arrhythmia therapy

4 Ambulatory Monitoring AKA “Holtor Monitoring”: 2 ECG leads are monitored and recorded by a device (cassette recorder) that patient wears for extended period of time. Provides continuous recording of ECG for 24 hours. Useful for detection of cardiac arrhythmias and determination if their presence correlates with patient symptoms.

5 Ambulatory Monitoring Patient diary of symptoms Analysis by both computer and cardiologist Event Recorders: prolonged monitoring for months or more. Useful in identifying rhythms that occur when patient is experiencing symptoms- palpitations, lightheadedness, etc.

Arrhythmia Detection

7 Stress Testing: Indications Evaluation of patients with chest discomfort suggestive of angina pectoris (coronary heart disease). Assessment of functional capacity in patients with documented CHD. Determine prognosis in high risk subsets. Screening of high risk individuals with atypical symptoms. Assess response to therapy including meds, PCI and CABG.

8 Stress Testing: Indications Evaluate patients with recent MI pre and post discharge. Exercise prescription for cardiac rehabilitation post MI. Screen patients with cardiac risk factors and certain occupations (pilots, bus and truck drivers, police officers, firemen).

9 Physiology of Ischemia Coronary blood flow- oxygen to myocardium. Exercise increases CO and coronary flow up to 5x. Blood flow through obstructed arteries unable to increase to meet demands: ischemia to tissue chest discomfortECG or imaging changes.

10 Physiology of Exercise Exercise increases CO and coronary blood flow. MET: Metabolic equivalents 1 met: resting O 2 consumption= 3.5ml/min/kg. Method: Treadmill testing most commonly used. Provides graded exercise/workloads (METs) and O 2 consumption.

11 Evaluation of Ischemia Electrocardiogram alone (Stress Electrocardiography) Nuclear (isotope) imaging + ECG Thallium 201, Tc 99 labeled Sestamibi Echocardiography (imaging) + ECG ECG + imaging improves sensitivity/specificity

12 Options for Stress Exercise using motorized treadmills Protocols using increasing speed/elevation reproduce quantifiable workloads at fixed intervals. Pharmacologic stress Adenosine and Dipyridamole Dobutamine Utilize ECG + imaging

13 Goals of Exercise Testing Increase heart rate and workload in incremental, objective fashion. Endpoints: Reproduce symptoms and/or diagnostic evidence of ischemia (ECG). Achieve target heart rate: 85-90% of PMHR if no ischemic changes. Dangerous arrhythmias Abnormal hemodynamics: ing BP during exercise means stop the test!

Exercise Protocols

Exercise Stress Testing Images.google.com

16 Stress Electrocardiography Sensitivity overall: 60-70% Single vessel CAD: 50% 2 vessel CAD: 65% 3 vessel CAD: 85% Specificity 80-85% For patients without symptoms/ECG changes, need to achieve 85-90% PMHR before concluding “negative test for ischemia.”

17 Stress Electrocardiography in Women High incidence of false positives in young, healthy women, no risk factors and atypical types of chest pain. Decreased sensitivity in women with documented CHD. Consider stress testing with imaging.

18 Stress Testing with Nuclear Imaging Isotope (Thallium 201 or Tc 99 sestamibi) distributes to myocardium via blood flow and intact cell membrane Na/K pump. Resting tissue (imaged before or several hours after stress) takes up isotope normally as perfusion is adequate at rest. Ischemic tissue (stress induced) beyond coronary stenosis does not take up isotope intracellulary- appears as “defect” on scan.

19 Stress Testing with Nuclear Imaging Resting images compared with stress images looking for reversible ischemia. Nuclear scans will also show areas of prior infarction if present: Defect on both resting and stress images.

20 Stress Echocardiography Myocardium with normal perfusion contracts normally, well defined using ultrasound. Heart normally gets smaller, with increased EF during exercise/dobutamine stress. Ischemic segments (that correlate with coronary artery that is obstructed) have decreased or absent contraction. If multiple or large, heart gets bigger, EF 

Stress Echo Images.google.com

22 Pharmacologic Stress Testing Dobutamine + Echocardiography Dipyridamole + Nuclear imaging Adenosine + Nuclear imaging Always combine ECG with imaging Nuclear Isotope: Tc 99 Sestamibi or Thallium 201 Echocardiography

23 Stress Testing + Imaging Clearly superior to stress testing with ECG alone Increases sensitivity to 85-90% Increases specificity to 90% Similar S/S with both exercise and pharmacologic stress + imaging Drawback is cost

24 Limitations of ECG for Ischemia LVH LBBB Digoxin WPW abnormality In patients with above, must use imaging when considering stress testing; ECG alone is worthless.

26 Echocardiography Non-invasive test, combines 2-D with doppler ultrasound to image the cardiac chambers, aorta, valves, myocardium, pericardium and blood flow. Transthoracic vs TEE Global and segmental LV function and EF Hypertrophy, chamber enlargement Detection of endocarditis TEE

27 Echocardiography Evaluation of Heart Failure Valvular stenosis, insufficiency Congenital defects, shunting Pericardial disease/effusions Prosthetic valves Ventricular or atrial thrombus

28 Radionuclide Ventriculography Isotope (Tc 99 ) used to label RBC’s. Passage of RBC’s over hundreds of cycles allows reconstruction of the beating heart. Excellent for evaluation of EF Some value in detecting wall motion abnormalities. Echocardiography provides more information and has replaced need for radionuclide ventriculography in most settings.

Radionuclide Angiography

Cardiac Catheterization AllRefer HealthImages.google.com

31 Rt Heart Catheterization Invasive procedure with risk Catheter advanced from central vein into RA, RV, PA and PCW positions. Pressures obtained. Oximetry performed if congenital heart disease suspected. PCW=LA=LVEDP if MV normal Measurement of cardiac output and SVR Invasive monitoring of critically ill patients. Complications: Pneumothorax, arterial puncture, infection, thrombosis.

Right Heart Pressures

33 Lt Heart Catheterization Catheter advanced from major artery into aorta, across Ao valve into LV; invasive. Pressures recorded: Identify AS, MS Angiography: Contrast (dye) can be injected into: LV to assess contractility and look for mitral valve regurgitation. Coronary arteries to identify and define presence/absence of stenosis/occlusions. Complications: Death, stroke, bleeding, arterial thrombosis/emboli.

Aortic Pressure

LV Pressure