Cardiac System
Fetal Circulation
Heart Embryology
| Mnemonic | Embryonic structure | Derivatives |
|---|---|---|
| Small | Sinus venosus | Smooth part of RA & Coronary sinus |
| Pump | Primitive atrium | Trabeculated part of RA & LA |
| Produces | Primitive ventricle | Trabeculated part of RV & LV |
| Big | Bulbus cordis | Smooth part of RV & LV |
| Turbulence | Truncus arteriosus | Aortic & Pulmonary trunk |
Action Potential of Cardiac Muscle Cells
| Phase | SA & AV Nodes | Atria & Ventricles |
|---|---|---|
| 0 | Ca current | Na current |
| 1 | - | K current |
| 2 | - | Ca & K current |
| 3 | K current | K current |
| 4 | Funny current: Na & K current | Leak current: K current |
Fick Principle
| Parameter | CO = VO2 ÷ (CaO2 - CvO2) |
|---|---|
| CO | Cardiac output (dL/min) |
| VO2 | O2 consumption rate (mL-O2/min) |
| CaO2 | Arterial O2 content (mL-O2/dL) |
| CvO2 | Venous O2 content (mL-O2/dL) |
Factors Affecting Stroke Volume {CAP}
- Contractility
- Afterload
- Preload
Cardiac & Vascular Function Curves
| Label | Examples |
|---|---|
| 1 | Catecholamines & Digitalis |
| 2 | Heart failure & Narcotics |
| 3 | Venopressors & Infusion |
| 4 | Venodilators & Hemorrhage & Spinal anesthesia |
| 5 | Vasopressors |
| 6 | Vasodilators & AV shunt |
Effects of Adrenergic Receptors
| Receptor | CO | SVR | MAP |
|---|---|---|---|
| α1 | ↓ | ↑ (1°) | ↑ |
| α2 | ↓ | ↓ | ↓ |
| β1 | ↑ (1°) | - | ↑ |
| β2 | ↑ | ↓ (1°) | ↓ |
Effects of Special Maneuvers
| Maneuver | Effect |
|---|---|
| Valsalva | ↓ Preload |
| Standing | ↓ Preload |
| Squatting | ↑ Preload |
| Leg rasie | ↑ Preload |
| Hand grip | ↑ Afterload |
Heart Sounds
| Heart Sound | Mechanism |
|---|---|
| S1 | MV & TV closure |
| S2 | AV & PV closure |
Approach to ECG
- Rate
- Rhythm
- Axis
- Interval
- Morphology
Bazett's Formula of Corrected QT Interval (QTc)
| Parameter | QTc = QT ÷ √RR |
|---|---|
| QT | QT interval |
| RR | RR interval |
ECG Localization of Coronary Blood Supply
| Location | Artery | Leads |
|---|---|---|
| Septal | LAD | V1 & V2 |
| Anterior | LAD | V3 & V4 |
| Apical | LAD / LCX / RCA | V5 & V6 |
| Lateral | LCX | I & aVL |
| Inferior | RCA & LCX | II & III & aVF |
| Posterior | RCA / LCX | V1 & V2 & V3 |
Views of Echocardiography
Cardiac Stress Test
Stress
- Exercise :: treadmill & bicycle
- Dobutamine
- Vasodilators :: Dipyridamole & Adenosine
Imaging
- Electrocardiography (ECG)
- Echocardiography
- Myocardial Perfusion Imaging (MPI)
- Thallium-201
- Technetium-99 sestamibi
- Technetium-99m tetrofosmin