In vivo electrophysiological study in mice is similar to that performed in humans. However in states of elevated end-diastolic pressure, the 'a' wave will increase and be palpable causing the 'second' impulse.The mouse is a common and cost-effective animal model for basic research, and the number of genetically engineered mouse models with cardiac phenotype is increasing.

Double impulse: in this the second impulse is from the exaggerated 'a' wave (' a' wave in figure above) that is normally not palpable and represents left ventricular filling during diastole.

A sustained impulse can also be seen in cardiac heart failure with a reduced ejection fraction.

Seen with left ventricular hypertrophy or states of outflow obstruction making the heart pump harder (e.g.

Forceful & Sustained: this outward movement is sustained throughout systole (would be a plateau shape on apex cardiogram) - indicative of a ventricle doing 'pressure' work.

Mitral regurgitation/aortic regurgitation/ventricular septal defect.

Hypermetabolic states (anemia, hyperthyroid, high-cardiac output).

Seen with states of increased 'volume' work:.

Forceful & Hyperdynamic: this is appreciated as a fast impulse with a large amplitude that terminates quickly it does not extend through systole.

There should be no impulses felt at other locations other than the apical region.

Should be a single impulse per cardiac cycle.

A normal, non-sustained tapping should be felt, that is no larger than 2-3cm in diameter.

The normal PMI is usually located near the mid-clavicular point at intercostal space 5.

Left 2nd intercostal pulsations? (dilated pulmonary artery).

Right 2nd intercostal pulsations? (aneurysm of ascending aorta).

Is there a parasternal heave? (right ventricular hypertrophy).

Is it single (normal) or a double impulse (e.g.Normally 5th intercostal space near the mid-clavicular line.Checklist of questions when examining PMI:.Somtimes, it will be difficult to palpate the PMI in certain conditions such as extreme tachycardia or shock.Along with palpating for near the apex, you should also palpate both lower parasternal, pulmonary, aortic, suprasternal and epigastric regions for a complete exam.When palpating for the PMI, your finger pads are more sensitive than finger tips.Retraction of chest wall: seen in biventricular hypertrophy or constrictive pericarditis.Left 2nd (or 3rd) intercostal pulsation: less common, can be seen with a dilated pulmonary artery.Right 2nd intercostal pulsation: may indicate an aneurysm of ascending aorta.Can also be normally seen with emphysema, children or a scaphoid abdomen and the very thin.Epigastric & subxiphoid movements: usually seen in with right ventricular hypertrophy, right ventricular dilation or an abdominal aortic aneurysm.Lateral displacement of the PMI (to left): usually seen in an enlarged heart (also seen in right large pleural effusion, right tension pneumothorax and left-sided pulmonary fibrosis).Double impulse: visible over the apical region seen in hypertrophic cardiomyopathy (this is caused by a second impulse after the first one from filling of the enlarged ventricle during diastole, 'a' wave in figure above).Observe a single outward impulse, representing the systolic contraction of the left ventricle ('E' wave in figure above).The normal PMI is usually located inside the mid clavicular point at intercostal space 5 (see figure below).Prior to observation, have your subject lay flat, you should observe the pulsations from the PMI from the side of the subject. It is best seen in thin-chested patients. Observation of the PMI can be challenging.

Cardiac ipulse