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FIG. 3.3 Purse-string suture within the coronary sinus for direct placement of the cannula.
Spillage of Cardioplegic Solution into the Right Atrium
When the balloon is inflated, it should minimize the amount of cardioplegic solution that enters the right atrium.
Cannulas with manually inflatable balloons are usually more effective in preventing backflow.
Inadequate Infusion of Cardioplegic Solution into the Right Coronary Vein
If the cannula is advanced too far into the coronary sinus, the inflated balloon may obstruct the right coronary
veincoronary sinus junction, thereby preventing any direct infusion of cardioplegic solution into the distribution of
the right coronary vein.
Retrograde Cardioplegic Infusion by the Open Technique
When bicaval cannulation has been performed and the right atrium is opened, cardioplegic solution can also be
administered directly into the coronary sinus. The balloon of the cannula is kept within the ostium of the coronary
sinus with a purse-string suture of 4-0 or 5-0 Prolene to prevent leakage of cardioplegic solution into the right
atrium (Fig. 3.3). This technique is particularly useful in pediatric cardiac surgery. Alternatively, a catheter with a
manually inflatable balloon is used. The balloon is inflated snugly to prevent backflow and to secure it in the
appropriate position.
Injury to the Conduction Tissue
The purse-string suture must be placed on the inside of the coronary sinus ostium to prevent injury to the
conduction tissue.
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4
Venting and Deairing of the Heart
Venting of the left side of the heart is an effective technique for cardiac decompression and air removal. It is
particularly useful when a dry field is desired for precise repair of intracardiac defects.
LEFT VENTRICULAR APICAL VENTING
The apex of the left ventricle provides a satisfactory and accessible site for venting and is particularly effective
for removal of air trapped in the ventricular cavity. However, it is rarely used today. Its relevance becomes
important when left ventricular venting is necessary before repeat sternotomy (see Repeat Sternotomy section in
Chapter 1).
Technique
The region of the left ventricular apex may be thin walled and covered by fat. The site chosen for insertion of the
vent must be well away from the branches of the coronary arteries and free of loose myocardial fat. There can be
bleeding from this ventricular site after removal of the vent catheter.
A double-armed, 2-0 nonabsorbable suture is passed in a U-shaped fashion through a suitable site near the left
ventricular apex buttressed with rectangular Teflon felt pledgets. The distance between the stitches on the
Teflon felt should be equal to the diameter of the vent catheter. The suture ends are then passed through a
narrow plastic tube as a tourniquet.
With a no. 11 knife blade, a 3- to 4-mm incision is made in the center of the U-shaped stitch. This opening in the
left ventricular apex is then dilated with a hemostat so that the vent catheter can be introduced gently into the left
ventricle. The tourniquet is then snugged down and secured to the vent catheter. If any catheter side hole
remains outside the heart, the vent will be ineffective.
When the heart is beating, gravity siphonage of the vent is usually adequate to decompress the heart and/or
remove trapped air bubbles. When the heart is fibrillating or motionless, particularly after the administration of
cardioplegia, the vent should be connected to gentle suction with adequate negative pressure to decompress the
heart. When the catheter is removed, the U-shaped stitch is tied down snugly and, if necessary, reinforced with a
few simple sutures.
Length of the Catheter
When an excessive length of the catheter is introduced into the left ventricle, its tip may traverse the aortic valve
and drain much of the pump flow. This rare problem can occur particularly in infants and small children (Fig. 4.1).
Suction Injury
Excessive suction can damage the left ventricular endocardium. For this reason, some vents have a double
lumen and the second lumen can be left open to air. Alternatively, and probably a safer technique, the vent
tubing can be vented with a one-way valve.
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FIG. 4.1 A vent catheter in the left ventricle crossing the aortic valve; pump flow is being suctioned.
FIG. 4.2 Repair of a tear in the left ventricular apex.
Tearing or Bleeding
When there is a tear or excessive bleeding from the left ventricular apex, the heart is decompressed. Long strips
of Teflon felt with nonabsorbable sutures are used to repair the tear, as in techniques for resection of a left
ventricular aneurysm (Fig. 4.2). This is probably most safely accomplished with the heart arrested with
cardioplegia.
Air in the Ventricular Cavity
If suction is too great or the apical opening is too large, air may be sucked into the left ventricular cavity around
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the vent site.
VENTING THROUGH THE RIGHT SUPERIOR PULMONARY VEIN
Venting through the right superior pulmonary vein is convenient, effective, and our technique of choice. After
clamping the aorta, through a stab wound in the center of a rectangular or oval purse-string suture on the right
superior pulmonary vein, the vent catheter is introduced into the left atrium and through the mitral valve into the
left ventricle. The purse-string suture is then passed through a narrow rubber tube and snugged down (Fig. 4.3).
Dissecting the Adventitia with the Suture
The adventitia within the purse-string suture over the right superior pulmonary vein should be dissected free to
prevent any obstruction to the smooth insertion of the vent catheter.
Injury to the Phrenic Nerve
When placing sutures on the right superior pulmonary vein, care should be taken to avoid the phrenic nerve,
which runs on the parietal pericardium along the anterolateral aspect of the right superior pulmonary vein. This is
more likely to occur in reoperations.
FIG. 4.3 Venting through the right superior pulmonary vein.
Reinforcing the Suture
When tissues are thin and friable, the purse-string suture should be reinforced with Teflon felt.
Air Embolism
Air embolism can be eliminated by cross-clamping the aorta or fibrillating the heart before placing the vent
catheter.
Vent Injury
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The catheter should be introduced gently and allowed to cross the mitral valve into the left ventricle without
excessive force to prevent injury of the mitral valve or perforation of the left atrium or left ventricle. This
complication is more likely when the heart becomes flaccid after infusion of cold cardioplegic solution. An
unexplained pooling of blood in the pericardial cavity should herald the occurrence of such a catastrophe. The
tear should be located and repaired with pledgeted sutures before continuing with the operation (Fig. 4.4).
Difficulty Introducing Vent into Left Atrium
Sometimes the vent will not pass easily into the left atrium. In these cases, the vent can be positioned after the
heart is opened by passing a right-angled clamp through an atrial septal defect or patent foramen ovale
into the opening on the right superior pulmonary vein. The vent is then pulled into the left atrium and positioned
appropriately.
FIG. 4.4 Vent injuries to the left ventricle and left atrium.
VENTING THROUGH THE SUPERIOR ASPECT OF THE LEFT ATRIUM
The left heart can also be vented through the superior aspect of the left atrium between the aorta and superior
vena cava. This technique is similar to that described earlier for the right superior pulmonary vein. It is rarely
used because it is cumbersome and control of bleeding from the vent site can be difficult (Fig. 4.5).
PULMONARY ARTERY VENTING
A simple but highly effective method to decompress the heart is to introduce a vent catheter through a purse-
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string suture on the anterior surface of the pulmonary artery (Fig. 4.6). This technique prevents overdistention of
both the right and left sides of the heart without the risk of systemic air embolism.
Pulmonary Artery Tear
The wall of the pulmonary artery may at times be paper thin and delicate, resulting in a tear at the vent site. This
can be prevented by using pledgets on the pursestring suture. The pulmonary artery tear, if it occurs, can easily
be repaired with direct suturing reinforced with pledgets.
VENTING THROUGH THE FORAMEN OVALE
We have found venting the left atrium and left ventricle through the foramen ovale in patients with congenital
heart disease very useful. With this technique, a dry field is maintained for precise repair of heart defects.
FIG. 4.5 Venting through the superior aspect of the left atrium.
FIG. 4.6 Venting through the pulmonary artery.
Technique
With the right atrium open, a small, right-angled vent is introduced through the foramen ovale and connected to
low suction. If the foramen ovale is not patent, a stab wound is made in the fossa ovalis. At the end of the
procedure, the vent is removed and the opening is closed with fine suture.
DEAIRING OF THE HEART
Air embolism is indeed a serious complication of cardiac surgery, and every precaution should be taken to
minimize its occurrence. A very effective way to minimize air embolism is to flood the operative field with carbon
dioxide. This can be achieved by introducing a constant flow of carbon dioxide gas through sterile intravenous
tubing anchored to the pericardium. The carbon dioxide displaces air (specifically nitrogen) and will dissolve in
the blood when the heart is allowed to fill.
The heart usually starts to beat soon after the aortic cross-clamp is removed. When warm blood is administered
in a retrograde fashion as the aortotomy is being closed in patients undergoing aortic valve replacement or as
the atriotomy is being closed in patients undergoing mitral valve surgery, the heart may at times begin to beat
spontaneously before the removal of the aortic cross-clamp (see Chapter 5). With each beat, the heart ejects
free air bubbles that may be trapped inside it. Every cardiac surgery team has its own preference to deair the
heart. We use the following technique.
The venting system, if used, is discontinued, and the heart is allowed to fill slowly by reducing the venous return.
The cardioplegia administration site on the aorta or a residual opening on the aortotomy site is kept open with
the tip of a right-angled clamp to facilitate venting and displacement of blood and air. At times, saline or blood
can be injected slowly through the left ventricular vent, if in place, to displace air and blood through the aortic
opening. The heart is shaken and the left atrial appendage is carefully invaginated into the left atrium to displace
air bubbles.
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Clots and the Left Atrial Appendage
Blood clots have a tendency to lodge in the left atrial appendage, particularly in patients with mitral stenosis and
chronic atrial fibrillation. This can easily be detected by transesophageal echocardiography. If present, these
clots must be removed.
Very gentle ventilation is begun. Often the heart has regained spontaneous rhythm and begins to eject blood
through the aortic opening. A slotted vent needle is now introduced into the aortic opening and high suction is
applied to it. The heart is allowed to fill and the aortic cross-clamp is removed. Transesophageal
echocardiography is used routinely to monitor left ventricular function and evaluate the adequacy of valvular
repair and function as well as the presence of residual air in the heart. As the left ventricular function improves,
good ejection expels residual air. Occasionally, despite all these maneuvers, a pocket of air appears to be
trapped in the apex of the left ventricle. Under these circumstances, the patient is placed in the Trendelenburg
position, a large-bore needle is introduced into the apex of the left ventricle, and blood and air are aspirated. The
right superior pulmonary vein, left atrial appendage, and roof of the left atrium in the gutter
between the superior vena cava and aorta may also be subjected to needle aspiration.
Needle Injury to the Left Ventricle
When the left ventricle appears to be dilated and thin, and the patient’s tissues are delicate, needle aspiration of
the left ventricle apex may be hazardous and cause bleeding. The needle site may require suture closure.
A long, 14- or 16-gauge needle passed through the anterior wall of the right ventricle and through the septum
into the left ventricle near the apex is a safe and effective technique to aspirate residual air. The right ventricle
entry site may need suture closure if bleeding continues after administration of protamine.
Another useful technique is to allow blood to eject from the left ventricle through the open end of left ventricular
vent cannula that is buried in a pool of blood in the pericardial cavity. Any air trapped in the ventricle or atrium
will gradually be ejected.
This technique requires the heart to be full and ejecting; otherwise, air may be sucked into the heart.
5
Surgery of the Aortic Valve
Aortic stenosis secondary to degenerative calcification, congenital bicuspid aortic valve disease, or rheumatic
fever is the most common indication for aortic valve replacement. Acute aortic insufficiency as a result of aortic
dissection, endocarditis, or balloon valvuloplasty requires urgent surgical intervention. Chronic aortic valve
regurgitation caused by the slow enlargement of the aortic root or dysfunction of the valve cusps is seen with
congenital abnormalities, most commonly bicuspid aortic valve, as well as rheumatic disease, endocarditis,
calcific cusp degeneration, and degenerative aortic wall disease. The timing of surgery is important to prevent
irreversible left ventricular dysfunction.
SURGICAL ANATOMY OF THE AORTIC VALVE
The aortic valve has three cup-shaped leaflets or cusps: the noncoronary cusp, the left cusp, and the right cusp.
These spring from three crescent-shaped valvular annuli within the expanded sinuses of Valsalva. The plane of
the aortic annuli forms the line of demarcation between the left ventricular cavity and the aorta.
Attachments of the aortic valve to the left ventricular outflow tract are both muscular and membranous (Fig. 5.1).
The three fibrous annuli are all associated with somewhat different structures. The noncoronary annulus is
singular in that it does not give rise to a coronary artery and is attached to the left ventricle only by membrane.
Adjoining halves of the left and noncoronary annuli and the small area beneath the intervening commissure, the
fibrous subaortic curtain, are continuous with the anterior leaflet of the mitral valve. Below the noncoronary and
right coronary annuli and the intervening commissure lie the central fibrous body and the membranous septum,
which are divided into atrioventricular and interventricular segments by the contiguous attachment of the nearby
tricuspid valve. This membrane usually circles under the noncoronary annulus and merges with the anterior
leaflet of the mitral valve. The bundle of His passes into the muscular ventricular septum just below the
membranous septum before dividing into left and right bundle branches. These travel inferiorly and downward
along the medial side of the left ventricular outflow tract. This conduction tissue is, therefore, close to portions of
the noncoronary and right coronary annuli. Behind the noncoronary sinus, and in direct opposition to it, are the
interatrial groove and parts of the left and right atria (thus explaining the rupture of an aneurysm of the
noncoronary sinus of Valsalva into these cavities).
Part of the right coronary annulus, as mentioned earlier, is directly attached through the central fibrous body to
the muscular septal wall. It courses along the right ventricular outflow tract, merging at its commissure with the
left coronary annulus adjacent to the pulmonary valve annulus. The right coronary artery originates from the
upper part of the right coronary sinus of Valsalva and courses down the right atrioventricular sulcus. The left or
anterior segment of the left coronary annulus underlies the only part of the aortic root not related to any of the
cardiac chambers. The right or posterior half of the left coronary annulus is in opposition to the left atrium. The
left main coronary artery arises from the upper part of the left sinus and runs a short but variable distance behind
it before dividing into its branches.
It is important to understand the functional anatomy of the aortic valve when considering valve repair or valve
preserving aortic root procedures. The aortic root consists of four components: the aortic annulus, the aortic
cusps, the sinuses of Valsalva, and the sinotubular junction. The aortic annulus is attached to the interventricular
septum and fibrous structures along 55% of its circumference, with the remaining 45% being attached to the
ventricular myocardium. The aortic cusps have a semilunar shape and the length of the base is normally 1.5
times the length of the free margin. The commissure is the highest point where two cusps meet, which is just
below the sinotubular junction. The annulus has a scalloped shape, and the diameter of the annulus in younger
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individuals is normally 15% to 20% larger than the diameter of the sinotubular junction. In older patients, these
two diameters are nearly equal. The average length of the free margin of an aortic cusp is 1.5 times the diameter
of the sinotubular junction. In general, the noncoronary cusp is slightly larger than the other two, and the left is
the smallest.
FIG. 5.1 A: Posteroanterior view of the heart with the aorta and pulmonary artery transected above the sinuses.
The atria have been removed at the level of the atrioventricular valves. The noncoronary sinus has been excised
at the noncoronary annulus and the aortic leaflets have been removed. B: Superior view into the aortic root. The
leaflets have been excised.
APPROACH TO THE AORTIC VALVE
Aortic valve surgery can be performed through a median sternotomy with a full or limited skin incision, or using
an upper ministernotomy (see Chapter 1). The distal ascending aorta is normally cannulated directly and a dual-
staged venous cannula is placed into the right atrium. In cases with diffuse calcific or atherosclerotic involvement
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