Chambers

The anatomic structures of the right atrium of importance include the fossa ovalis which is the obliterated ostium secundum. This is surrounded by a limbus or raised area of tissue which encircles the fossa ovalis at all but its inferior margin. There is a wide-based, blunt atrial appendage. The Eustachian valve exists as a flap at the orifice of the inferior vena cava and the thebesian valve similarly exists at the orifice of the coronary sinus. There is a crista terminalis which surrounds the base of the right atrial appendage and thus separates the trabeculated from the nontrabeculated portion of the atrium.

The left atrium receives pulmonary venous drainage usually from right and left superior and inferior pulmonary veins which drain into the posterior portion of the left atrium. Unlike the blunt right atrial appendage, the left atrial appendage is long, narrow, and fern-shaped, and there is no crista terminalis in the left atrium. Unlike the right atrium, the left atrium is not trabeculated. The left atrial appendage is the only trabeculated structure in the left atrium.

The right ventricle is usually located anteriorly and to the right side of the left ventricle. The inflow of the right ventricle is via the tricuspid valve. Flow enters the right ventricle into a large sinus portion and a smaller infundibulum or outlet portion just proximal to the pulmonary valve. The sinus and infundibular portions of the right ventricle are coarsely trabeculated. This is the major distinction between the right ventricle and the left ventricle, i.e. the right ventricle is much coarser than the smoother left ventricle, and this is an important differentiation factor on ventriculography.

A septum lies between the inflow and outflow portions of the right ventricle and thus lies adjacent to the pulmonary valve. This septum is called the infundibular septum or the conal septum or the crista supraventricularis. These are synonymous terms and the function of this septum is to separate the pulmonary valve from the confluence of the aortic valve, mitral valve and tricuspid valve. The fusion of the latter three structures forms the fibrous skeleton of the heart.

The tricuspid valve has three leaflets, and its anatomy will be described later. The papillary muscles which support these three leaflets differ in basic anatomy from the papillary muscle arrangement of the mitral valve in the left ventricle. There is a single large anterior papillary muscle attached to the anterior free wall in the case of the tricuspid valve. There are multiple smaller posterior papillary muscles attached partly to the free wall of the ventricle and partly to the interventricular septum.

The left ventricle consists of a large sinus portion or inflow portion which includes the mitral valve and the apex and a much smaller outflow portion beneath the aortic valve. The inflow and outflow portions of the left ventricle are separated by the anterior leaflet of the mitral valve. Although the wall of the left ventricle is trabeculated, the trabeculae are fine compared to the coarse trabeculations in the right ventricle. The outflow portion of the left ventricle lies anteriorly and to the right of the anterior leaflet of the mitral valve. It should be noted that this outflow portion of the left ventricle abutts the inflow portion of the right ventricle, the two being separated by the interventricular septum. The anterior leaflet of the mitral valve attaches to the interventricular septum as well as a portion of the aortic valve. This will be described further later on.

On the right ventricular side, only the septal leaflet of the tricuspid valve attaches to the septum, whereas on the left ventricular side both the anterior leaflet of the mitral valve as well as a portion of the aortic valve attach to the interventricular septum. The left half of the anterior leaflet of the mitral valve is in fibrous continuity with the aortic valve in an area called the aortic mitral annulus. This is shown in Figure 1.1 and will be described later. This is the most important figure in understanding valvular cardiac anatomy and what the implications are for suture placement during valve replacement in terms of juxtaposing structures. The papillary muscle anatomy in the left ventricle is generally uniform and consists of two large papillary muscles attached to the free wall. These are an anterolateral papillary muscle and a posteromedial papillary muscle. Both of these attach to the free wall of the left ventricle unlike the right ventricle where some papillary muscles attach to the interventricular septum. The anterolateral and posteromedial papillary muscles attach to both the anterior and posterior leaflets of the mitral valve. The anterolateral papillary muscle is less prone to ischemia than the posterome-dial papillary muscle because the anterolateral papillary muscle is supplied by septal branches of the left anterior descending artery as well as the circumflex artery. The posteromedial papillary muscle is supplied by only the right coronary artery.

With regard to the interventricular septum, the right and left ventricular septal surfaces are asymmetric due to the presence of the infundibulum in the right ventricle only. Also, the higher pressure in the left ventricle makes the left ventricular septal surface concave with respect to the convexed right ventricular surface.

The axis of the right and left ventricular outflow tracts are also different with the RV outflow tract being directly superiorly oriented while the LV outflow tract is angled towards the right. The atrial-ventricular septum separates the atrium from the ventricle and consists of a membranous AV septum and a muscular AV septum. The membranous AV septum is associated with the fibrous skeleton of the heart. Directly between the membranous and muscular AV septum lies the AV node and conduction tissue.

Fossa Ovalis Fibrous Skeleton

Fig. 1.1a. Anatomic valvular relationships and hazardous surgical areas. 1) Bundle of His: vulnerable just under junction of right and noncoronary cusps of the aortic valve (RCC and NCC). It is also found coursing adjacent to the septal leaflet of the tricuspid valve. It is particularly vulnerable at the junction of the septal and anterior leaflets of the tricuspid valve. 2) Atrioventricular node: vulnerable in the region between the coronary sinus and tricuspid valve annulus. Also found at the 2 o'clock position of anterior leaflet of mitral valve. 3) Junction of the aortic left and noncoronary cusp (LCC and NCC): These two cusps may sustain injury when suturing at the 10 o'clock position on the mitral annulus. 4) Circumflex artery, coronary sinus, and left atrioventricular groove: may be injured by deep sutures at the 7 o'clock position of the mitral annulus.

Fig. 1.1a. Anatomic valvular relationships and hazardous surgical areas. 1) Bundle of His: vulnerable just under junction of right and noncoronary cusps of the aortic valve (RCC and NCC). It is also found coursing adjacent to the septal leaflet of the tricuspid valve. It is particularly vulnerable at the junction of the septal and anterior leaflets of the tricuspid valve. 2) Atrioventricular node: vulnerable in the region between the coronary sinus and tricuspid valve annulus. Also found at the 2 o'clock position of anterior leaflet of mitral valve. 3) Junction of the aortic left and noncoronary cusp (LCC and NCC): These two cusps may sustain injury when suturing at the 10 o'clock position on the mitral annulus. 4) Circumflex artery, coronary sinus, and left atrioventricular groove: may be injured by deep sutures at the 7 o'clock position of the mitral annulus.

Mitral Junction

Fig. 1.1b. Relative positions of heart valves on a PA chest film.

Herbal Remedies For Acid Reflux

Herbal Remedies For Acid Reflux

Gastroesophageal reflux disease is the medical term for what we know as acid reflux. Acid reflux occurs when the stomach releases its liquid back into the esophagus, causing inflammation and damage to the esophageal lining. The regurgitated acid most often consists of a few compoundsbr acid, bile, and pepsin.

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