Cardiovascular system- L3 Faisal I. Mohammed, MD, PhD Yanal A. Shafagoj University of Jordan

Electrocardiogram ECG or EKG Composite record of action potentials produced by all the heart muscle fibers Compare tracings from different leads with one another and with normal records 3 recognizable waves P, QRS, and T University of Jordan 2

The Electrocardiogram The major deflections and intervals in a normal ECG include: P wave - atrial depolarization P-Q interval - time it takes for the atrial kick to fill the ventricles QRS wave - ventricular depolarization and atrial repolarization S-T segment - time it takes to empty the ventricles before they repolarize (the T wave) 3

Correlation of ECG Waves and Systole Systole means ventricular contraction and diastole means ventricular relaxation. Cardiac cycle events are: Cardiac action potential arises in the SA node → P wave Atrial systole (Atrial contraction) Action potential enters AV bundle and leaves to the ventricles → QRS complex which masks atrial repolarization (un-recordable) Contraction of ventricles (systole) Begins shortly after QRS complex appears and continues during S-T segment Repolarization of ventricular fibers → T wave Ventricular relaxation/ diastole University of Jordan 4

Cardiac Cycle All events associated with one heartbeat Systole and diastole of atria and ventricles In each cycle, atria and ventricles alternately contract and relax During atrial systole, ventricles are relaxed During ventricle systole, atria are relaxed Forces blood from higher pressure to lower pressure During relaxation period, both atria and ventricles are relaxed The faster the heart beats, the shorter the relaxation period Systole and diastole lengths shorten slightly University of Jordan 5

Cardiac Cycle Cardiac cycle refers to all events associated with blood flow through the heart Systole – contraction of heart ventricles Diastole – relaxation of heartventricles 6

Cardiac Cycle 7 Atrial systole 0.1 second Atrial diastole 0.7 second Ventricular systole 0.3 second Isovolumic contraction phase Rapid ejection period Slow ejection period Ventricular diastole 0.5 seconds Rapid filling phase Slow filling (Diastasis) Atrial contraction phase 7

Phases of the Cardiac Cycle 8

University of Jordan 9 20 40 60 80 100 120 (d) Volume in 20 40 60 80 100 120 (d) Volume in ventricle (mL) (c) Heart sounds (b) Pressure (mmHg) (a) ECG P R Q S Dicrotic wave Left atrial pressure Aortic Left ventricular T 130 Atrial contraction Isovolumetric relaxation Ventricular ejection filling (e) Phases of the cardiac cycle Stroke volume 0.3 sec 0.1 sec 0.4 sec systole Relaxation period S1 S2 S3 S4 4 7 1 2 3 5 6 Atrial depolarization Begin atrial systole End (ventricular) diastolic volume Ventricular depolarization Isovolumetric contraction Begin ventricular ejection End (ventricular) systolic volume 20 40 60 80 100 120 (d) Volume in ventricle (mL) (c) Heart sounds (b) Pressure (mmHg) (a) ECG P R Q S Dicrotic wave Left atrial pressure Aortic Left ventricular T 130 Atrial contraction Isovolumetric relaxation Ventricular ejection filling (e) Phases of the cardiac cycle 0.3 sec 0.1 sec 0.4 sec systole Relaxation period S1 S2 S3 S4 4 6 1 2 3 5 Atrial depolarization Begin atrial systole End (ventricular) diastolic volume Ventricular depolarization Isovolumetric contraction Begin ventricular ejection 20 40 60 80 100 120 (d) Volume in ventricle (mL) (c) Heart sounds (b) Pressure (mmHg) (a) ECG P R Q S Dicrotic wave Left atrial pressure Aortic Left ventricular T 130 Atrial contraction Isovolumetric relaxation Ventricular ejection filling (e) Phases of the cardiac cycle Stroke volume 0.3 sec 0.1 sec 0.4 sec systole Relaxation period S1 S2 S3 S4 8 1 2 3 4 5 6 7 Atrial depolarization Begin atrial systole End (ventricular) diastolic volume Ventricular depolarization Isovolumetric contraction Begin ventricular ejection End (ventricular) systolic volume Begin ventricular repolarization 20 40 60 80 100 120 (d) Volume in ventricle (mL) (c) Heart sounds (b) Pressure (mmHg) (a) ECG P R Q S Dicrotic wave Left atrial pressure Aortic Left ventricular T 130 Atrial contraction Isovolumetric relaxation Ventricular ejection filling (e) Phases of the cardiac cycle Stroke volume 0.3 sec 0.1 sec 0.4 sec systole Relaxation period S1 S2 S3 S4 8 9 1 2 3 4 5 6 7 Atrial depolarization Begin atrial systole End (ventricular) diastolic volume Ventricular depolarization Isovolumetric contraction Begin ventricular ejection End (ventricular) systolic volume Begin ventricular repolarization Isovolumetric relaxation 20 40 60 80 100 120 (d) Volume in ventricle (mL) (c) Heart sounds (b) Pressure (mmHg) (a) ECG P R Q S Dicrotic wave Left atrial pressure Aortic Left ventricular T 130 Atrial contraction Isovolumetric relaxation Ventricular ejection filling (e) Phases of the cardiac cycle Stroke volume 0.3 sec 0.1 sec 0.4 sec systole Relaxation period S1 S2 S3 S4 10 1 2 3 4 5 6 7 8 9 Atrial depolarization Begin atrial systole End (ventricular) diastolic volume Ventricular depolarization Isovolumetric contraction Begin ventricular ejection End (ventricular) systolic volume Begin ventricular repolarization Isovolumetric relaxation Ventricular filling 20 40 60 80 100 120 (d) Volume in ventricle (mL) (c) Heart sounds (b) Pressure (mmHg) (a) ECG P R Q S Dicrotic wave Left atrial pressure Aortic Left ventricular T 130 Atrial contraction Isovolumetric relaxation Ventricular ejection filling (e) Phases of the cardiac cycle 0.3 sec 0.1 sec 0.4 sec systole Relaxation period S1 S2 S3 S4 4 5 1 2 3 Atrial depolarization Begin atrial systole End (ventricular) diastolic volume Ventricular depolarization Isovolumetric contraction 20 40 60 80 100 120 (d) Volume in ventricle (mL) (c) Heart sounds (b) Pressure (mmHg) (a) ECG P R Q S Dicrotic wave Left atrial pressure Aortic Left ventricular T 130 Atrial contraction Isovolumetric relaxation Ventricular ejection filling (e) Phases of the cardiac cycle 0.3 sec 0.1 sec 0.4 sec systole Relaxation period S1 S2 S3 S4 4 1 2 3 Atrial depolarization Begin atrial systole End (ventricular) diastolic volume Ventricular depolarization 1 20 40 60 80 100 120 (d) Volume in ventricle (mL) (c) Heart sounds (b) Pressure (mmHg) (a) ECG P R Q S Dicrotic wave Left atrial pressure Aortic Left ventricular T 130 Atrial contraction Isovolumetric relaxation Ventricular ejection filling (e) Phases of the cardiac cycle 0.3 sec 0.1 sec 0.4 sec systole Relaxation period S1 S2 S3 S4 Atrial depolarization 1 20 40 60 80 100 120 (d) Volume in ventricle (mL) (c) Heart sounds (b) Pressure (mmHg) (a) ECG P R Q S Dicrotic wave Left atrial pressure Aortic Left ventricular T 130 Atrial contraction Isovolumetric relaxation Ventricular ejection filling (e) Phases of the cardiac cycle 0.3 sec 0.1 sec 0.4 sec systole Relaxation period S1 S2 S3 S4 2 Atrial depolarization Begin atrial systole 1 20 40 60 80 100 120 (d) Volume in ventricle (mL) (c) Heart sounds (b) Pressure (mmHg) (a) ECG P R Q S Dicrotic wave Left atrial pressure Aortic Left ventricular T 130 Atrial contraction Isovolumetric relaxation Ventricular ejection filling (e) Phases of the cardiac cycle End (ventricular) diastolic volume 0.3 sec 0.1 sec 0.4 sec systole Relaxation period S1 S2 S3 S4 2 3 Atrial depolarization Begin atrial systole University of Jordan 9

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Stroke Volume SV = end diastolic volume (EDV) minus end systolic volume (ESV) EDV = amount of blood collected in a ventricle at the end of diastolic phase ESV = amount of blood remaining in a ventricle after contraction 11

Cardiac cycle …cont End diastolic volume (EDV) – End systolic volume (ESV) = Stroke volume (SV) SV X heart rate (HR) = cardiac output (CO) Ejection fraction = SV/EDV Autonomic control of cardiac cycle (pump) 12

Cardiac Output CO = volume of blood ejected from left (or right) ventricle into aorta (or pulmonary trunk) each minute CO = stroke volume (SV) x heart rate (HR) In typical resting male 5.25L/min = 70mL/beat x 75 beats/min Entire blood volume flows through pulmonary and systemic circuits each minute University of Jordan 13

Thank You 14