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The standard model used to understand the cardiac action potential is that of the ventricular myocyte. Outlined below are the five phases of the ventricular myocyte action potential, with reference also to the SAN action potential. Figure 2a: Ventricular action potential (left) and sinoatrial node action potential (right) waveforms.
Repolarization of the ventricle happens in the opposite direction of depolarization and is negative current, signifying the relaxation of the cardiac muscle of the ventricles. But this negative flow causes a positive T wave; although the cell becomes more negatively charged, the net effect is in the positive direction, and the ECG reports this ...
The action potential of a ventricular myocyte. In electrocardiography, the ventricular cardiomyocyte membrane potential is about −90 mV at rest, [1] which is close to the potassium reversal potential. When an action potential is generated, the membrane potential rises above this level in five distinct phases. [1]
A heart rate below normal is called "bradycardia" (<60 in adults) and above normal is called "tachycardia" (>100 in adults). A complication of this is when the atria and ventricles are not in synchrony and the "heart rate" must be specified as atrial or ventricular (e.g., the ventricular rate in ventricular fibrillation is 300–600 bpm ...
Schematic representation of normal ECG In electrocardiography , the ST segment connects the QRS complex and the T wave and has a duration of 0.005 to 0.150 sec (5 to 150 ms). It starts at the J point (junction between the QRS complex and ST segment) and ends at the beginning of the T wave.
During ventricular diastolic filling, the elevated atrial pressure is transmitted to the LV during filling so that LV end-diastolic volume (and pressure) increases. This would cause the afterload to increase if it were not for the reduced outflow resistance (due to mitral regurgitation) that tends to decrease afterload during ejection.
Normal pressure range (in mmHg) [5] Central venous pressure: 3–8 Right ventricular pressure: systolic: 15–30 diastolic: 3–8 Pulmonary artery pressure: systolic: 15–30 diastolic: 4–12 Pulmonary vein/ Pulmonary capillary wedge pressure. 2–15 Left ventricular pressure: systolic: 100–140 diastolic: 3–12
Cardiac (ventricular) systole: Both AV valves (tricuspid in the right heart (light-blue), mitral in the left heart (pink)) are closed by back-pressure as the ventricles are contracted and their blood volumes are ejected through the newly-opened pulmonary valve (dark-blue arrow) and aortic valve (dark-red arrow) into the pulmonary trunk and ...