Добавил:
Sekretar
kiopkiopkiop18@yandex.ru
t.me/Prokururor I Вовсе не секретарь, но почту проверяю
Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз:
Предмет:
Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3683_Библиотеки_им_академика_М_И_Перельмана
.pdf
relief of recurrent effusions by subxiphoid pericardial drainage or a pericardial window procedure.
Right Atrial Extension of Tumors below the Diaphragm
Abdominal and pelvic tumors may invade and grow up the inferior vena cava to reach the right atrium. Renal cell
carcinoma is the most common of these tumors. The surgery is approached through an abdominal incision to
ensure resectability of the renal tumor. It may be feasible to withdraw the tumor from the subdiaphragmatic
inferior vena cava transabdominally. If this is not possible, a median sternotomy is performed and
cardiopulmonary bypass achieved for systemic cooling. During a short period of deep hypothermic circulatory
arrest, the right atrium is opened, and the cardiac surgeon assists the urologist to withdraw the tumor down into
the abdominal segment of inferior vena cava and remove it. Cardiopulmonary bypass is reinstituted, the patient is
rewarmed, and weaned from bypass in the usual manner.
Cannulation of Right Atrium
A large straight or right angled venous cannula is placed through a purse-string suture into the right atrium for a
limited distance to avoid contact with the tumor. A dual-staged cannula should not be used.
Coagulopathy
These patients have significant problems with coagulopathy following cardiopulmonary bypass with profound
hypothermia. This technique should be reserved for patients in whom the tumor cannot be removed through the
inferior vena cava just below the diaphragm.
Данная книга находится в списке для перевода на русский язык сайта https://meduniver.com/
13
Surgery for Atrial Fibrillation
The Maze procedure was developed and modified by Dr. James Cox and has proved to be effective for treating
atrial fibrillation associated with valvular and ischemic heart disease and isolated atrial fibrillation refractory to
medical therapy. The Cox-Maze III cut and sew technique is the gold standard against which modifications
should be measured because of its greater than 95% cure of atrial fibrillation. However, this procedure adds
significantly to the aortic clamp time and incurs the risk of serious bleeding from the back of the heart. Several
different energy sources have been used to ablate atrial tissue, creating the same lesion pattern as the Maze III
operation in less time and with less bleeding potential. The ideal energy source for performing a full or partial
Maze procedure should be fast and produce a transmural lesion without causing damage to surrounding
structures. It would be advantageous if it could be applied through a minimally invasive approach without the use
of cardiopulmonary bypass. Radiofrequency systems heat tissue, causing thermal injury and conduction block.
Unipolar systems have been modified by adding irrigation to minimize the surface charring, which can lead to
thrombus formation, and to prevent injury to adjacent structures, particularly the esophagus. Bipolar
radiofrequency clamps can be used epicardially, assure transmural lesions, and avoid damage to surrounding
tissue. However, not all of the Maze lesions can be performed with the bipolar device. Cryoablation is performed
with a nitrous oxide-cooled probe. Its advantage is the lack of tissue vaporization, resulting in a smooth tissue
surface. It takes 2 to 3 minutes to produce each transmural lesion. Microwave produces conduction block by
thermal injury, but unlike radiofrequency, it does not cause surface charring. It is also more likely to produce a
transmural lesion because of greater tissue penetration. Focused ultrasonography results in deep heating and
coagulati on necrosis, and can be delivered through tubular or planar transducers. Both the Nd:YAG laser and
infrared coagulator produce transmural photocoagulation necrosis at relatively low tissue temperatures with no
tissue vaporization. We have used a combination of bipolar radiofrequency clamp and a cryoprobe to recreate
the lesions of Cox-Maze III procedure (which is called Cox-Maze IV procedure). This procedure can also be
performed using a combination of other energy sources. Patients with chronic atrial fibrillation undergoing mitral
valve surgery are candidates for this procedure, which adds approximately 20 minutes to the cross-clamp time.
TECHNIQUE
A median sternotomy is used, and standard bicaval cannulation is performed. The initial right atrial incisions and
lesions are accomplished on cardiopulmonary bypass with a beating heart.
We first encircle right and left pulmonary veins. Using the radiofrequency clamp, we create transmural lesions
around the pulmonary veins (Fig. 13.1). After tightening the caval tourniquets, the right atrial appendage is
excised. Using the radiofrequency clamp passed through the right atrial appendage opening, a linear lesion is
created toward SVC, on the aortic side of the appendage (Fig. 13.2). We then perform a vertical incision on the
right atrial free wall. Using the bipolar clamp, linear lesions are created up to SVC and down to IVC (Fig. 13.3).
P.200
FIG. 13.1 The bipolar clamp is used to create lesions around the right and left pulmonary veins.
FIG. 13.2 Excision of the right atrial appendage and lesion line on the aortic side of SVC.
With the atrial free wall retracted, linear endocardial lesions are created from the superior aspect of atriotomy to
2 o'clock and 10 o'clock positions of the tricuspid vale annulus (Fig. 13.4). These two lesion sets are usually
performed with bipolar radiofrequency clamp on the free wall to save time. The segment near AV groove needs
to be performed endocardially with cryoprobe.
Omitting Right Atrial Ablation Lines
It is generally agreed that most of the right-sided lesions are not required in most patients. However, the ablation
line from the coronary sinus inferiorly into the inferior vena cava should probably be included to prevent right
atrial flutter (Fig. 13.5).
After placing a retrograde cardioplegia catheter, we then close the right atriotomy and start the left-sided lesion
set. Aorta is cross-clamped and heart is arrested. Left atrial appendage is amputated and through the opening, a
lesion is created between the left atrial appendage opening and left superior pulmonary vein (Fig. 13.6). Left
atrial appendage base closed. We then mark the coronary sinus with a marking pen between the right and left
coronary artery circulations. A standard left atriotomy is performed, with extension superiorly into the dome of left
Данная книга находится в списке для перевода на русский язык сайта https://meduniver.com/
P.201
atrium or inferiorly around the right inferior pulmonary vein. Using the bipolar clamp, a lesion is created from the
inferior aspect of the atriotomy to the inferior left pulmonary vein. Similarly, another lesion is created toward the
mitral valve annulus and across the coronary sinus (Fig. 13.7). We then use the cryoprobe to create endocardial
lesions connecting the PV lesions and to connect the left PV lesion set to the annulus of the mitral valve (Fig.
13.8). Lastly, the epicardial cryoablation of the coronary sinus is performed to complete the mitral isthmus
ablation.
FIG. 13.3 Linear lesions are created through the atriotomy up the SVC and down to IVC.
FIG. 13.4 Radiofrequency lesions from the amputated appendage to the tricuspid valve annulus and from the
atriotomy free wall to the tricuspid annulus.
Patent Foramen Ovale
If a patent foramen ovale or small atrial septal defect is present, the right atrial lesions must be performed after
the aorta is cross-clamped or with induced ventricular
fibrillation to prevent air embolism. The absence of a patent foramen ovale must be confirmed by
transesophageal echocardiography in the operating room before instituting cardiopulmonary bypass.
FIG. 13.5 Ablation line from coronary sinus into the vena cava to prevent atrial flutter.
FIG. 13.6 After amputation of left atrial appendage, a lesion is created to the left pulmonary veins using the
bipolar clamp.
Transmural Lesions
The bipolar radiofrequency clamp has the distinct advantage of increasing the likelihood of transmural lesions.
The clamp needs to be applied a minimum of two times to increase the likelihood of transmurality. We apply
cryoprobe for 2 to 3 minutes depending on the atrial tissue thickness. Discoloration of the endocardium should
be apparent.
Bleeding from the Base of the Left Atrial Appendage
If the base of the appendage is ablated with the radiofrequency probe and then the appendage is amputated and
oversewn, the ablated tissue may tear when the heart fills with blood and contracts. The appendage should be
either surgically amputated or ablated with radiofrequency energy, not both, to avoid this complication.
Данная книга находится в списке для перевода на русский язык сайта https://meduniver.com/
FIG. 13.7 Radiofrequency lesions within the left atrium (see text).
FIG. 13.8 Completed lesion set inside the left atrium.
Thrombus in the Left Atrial Appendage
If thrombus is present in the left atrial appendage, it should be amputated.
Stenosis of the Pulmonary Vein Orifices
The healing process that takes place after radiofrequency ablation may lead to fibrosis and contraction of tissue.
The lesions surrounding the orifices of the pulmonary veins should be well within the left atrium to avoid
subsequent scarring and pulmonary vein stenosis.
Injury to the Valve Leaflet Tissue
The radiofrequency energy will damage the valve leaflet tissue. Therefore, care must be exercised when
creating lesions extending onto the tricuspid and especially the mitral valve annulus. Because of this
concern, some surgeons prefer to use a cryoprobe to make these lesions because cryoablation does not
permanently damage leaflet tissue. It is also important to carry out these lesions before any valve repair or
replacement procedure is performed.
Injury to the Circumflex Coronary Artery
P.202
In performing the ablation from the left pulmonary veins to the mitral annulus, care must be taken because the
circumflex coronary artery underlies this area. Transmural lesions may injure this artery. For this reason,
cryoablation may be preferable in this location. Alternatively, the risk of damaging the artery can be reduced by
maintaining flow through the vessel during the ablation. This is accomplished by the administration of antegrade
cardioplegic solution.
Injury to the Esophagus
Esophageal injury has been seen with dry radiofrequency ablation of the posterior left atrial wall. By lifting the
cryoprobe when adhered to the left atrial tissue, one may minimize the risk of injury to surrounding tissue. The
goal of any energy source used to create lines of ablation is to achieve transmural lesions without injuring
adjacent tissues and structures.
Thrombogenic Foci
Ablation lines created by some energy sources have been reported to result in thrombus formation within the left
atrium. It may be prudent to anticoagulate all patients, regardless of cardiac rhythm, with warfarin for at least 3 to
6 months to prevent this devastating complication.
The planned mitral valve procedure is now performed. Postoperative atrial arrhythmias are common and do not
mean that the surgery has been unsuccessful. In general, these patients are maintained on amiodarone for 3 to 6
months postoperatively.
Freedom from atrial tachyarrythmia at 12 months is estimated around 80% to 90% in patients who undergo Cox-
Maze IV procedure. Pulmonary vein isolation alone is the simplest ablation procedure with a success rate of 60%
to 70%.
The bipolar radiofrequency clamps can be used to create the pulmonary vein encircling lesions on a beating
heart. This procedure can be safely and quickly performed in patients with atrial fibrillation undergoing coronary
bypass or aortic valve operations.
Many surgeons perform a modified left-sided Maze, which may or may not include the lesion connecting the
pulmonary vein encircling lines and/or the ablation line from the left pulmonary vein encircling lesion to the mitral
annulus. This lesion set has a higher success rate of 70% to 85%.
Failure of Procedure
Patients with enlarged left atria, longer duration of atrial fibrillation preoperatively, coronary disease, and/or
advanced age are less likely to respond to a modified Maze procedure.
Postoperative Left Atrial Flutter
Because of concern regarding injury to the circumflex coronary artery, some surgeons omit the ablation line
connecting the left pulmonary vein encircling lesion to the mitral annulus. This may allow left isthmus reentry to
occur postoperatively, resulting in left atrial flutter, which can be difficult to control.
Left Atrial Appendage Excision
The left atrial appendage has several beneficial physiologic functions in patients who are in sinus rhythm.
However, these are probably outweighed by the role that the appendage plays in thrombus formation in patients
with atrial fibrillation. Excising the left atrial appendage during cardiac surgery in patients with atrial fibrillation
removes the most important source of thromboembolism, and has been proposed as a stand-alone treatment for
Данная книга находится в списке для перевода на русский язык сайта https://meduniver.com/
chronic atrial fibrillation.
14
Patent Ductus Arteriosus
INCISION
The ductus arteriosus can be adequately exposed through a small left anterior thoracotomy. A limited left
posterolateral thoracotomy through the third or fourth intercostal space partially dividing the latissimus dorsi
muscle and preserving the serratus anterior muscle provides good exposure and is more commonly used. The
skin incision can be quite short, especially in premature infants. If a right aortic arch and right ductus are present,
a right thoracotomy approach must be used.
SURGICAL ANATOMY
The ductus arteriosus runs parallel to the aortic arch from the superior aspect of the origin of the left pulmonary
artery and passes through the pericardium to join the medial margin of the aorta at an acute angle just opposite
the origin of the left subclavian artery (Fig. 14.1). The left vagus trunk enters the thorax from the root of the neck
in a groove between the left subclavian artery and the left common carotid artery, crosses the aortic arch and the
ductus arteriosus, and continues downward. The recurrent laryngeal branch curves around the ductus arteriosus
and extends back upward into the neck. The vagus nerve gives rise to many other small branches that are
important tributaries to the pulmonary and cardiac plexuses. There are usually some lymph nodes buried in the
hilum of the left lung that sometimes extend upward near the inferior margin of the ductus arteriosus. The left
phrenic nerve enters the thorax medial to the vagus nerve and continues downward on the pericardium.
Technique for Exposing and Dissecting the Ductus Arteriosus
The left lung is retracted inferiorly and medially to expose the ductus arteriosus. The parietal pleura is divided
longitudinally behind the vagus nerve if the intention is to retract the vagus nerve medially. Alternatively, a pleural
incision may be made between the vagus and phrenic nerves when the vagus nerve is to be retracted laterally
(Fig. 14.1). The incision of choice is extended superiorly along the left subclavian artery and inferiorly to the left
hilum. The pleural edges are then suspended.
In an infant, the ductus is exposed by sharp dissection with scissors both from above and below. A blunt right-
angled clamp or preferably a Waterson dissector/Dennis-Browne is then carefully passed above and below the
ductus to create a plane for its ligation or division. The ductus can most often be occluded by the application of a
metal clip.
Recurrent Laryngeal Nerve Location with Medial Retraction
To facilitate dissection and exposure of the posterior aspect of the ductus arteriosus, many surgeons prefer that
the vagus nerve and its recurrent laryngeal branch be reflected medially on the pleural flap (Fig. 14.2). The
surgeon should be aware that traction of the nerve toward the pulmonary artery causes the recurrent nerve to lie
along a diagonal course behind the ductus arteriosus. Therefore, care must be taken to ensure that the recurrent
nerve is not injured during dissection. Alternatively, the vagus nerve and its branches can be isolated and
retracted laterally to ensure their protection during the process of dissection of the posterior wall of the ductus.
Complete Exposure of the Ductus
Special care should be taken when dissecting near the angle between the pulmonary artery and the ductus
arteriosus because the ductus is particularly susceptible to injury. A lappet of pericardium usually covers the
ductus anteriorly. It should be dissected free to ensure complete exposure of the ductus (Fig. 14.3). Similarly, it is
Данная книга находится в списке для перевода на русский язык сайта https://meduniver.com/
P.206
essential to separate the cranial aspect of the ductus from the transverse aortic arch—this maneuver more
clearly demonstrates the angle that the clip will need to follow so as not to either impinge upon the arch or only
partially occlude the ductus (Fig. 14.4).
Technique for Dividing and Ligating the Ductus Arteriosus
The vagus and recurrent laryngeal nerves are identified so that they are not divided inadvertently. Two heavy
Ethibond sutures are individually passed behind the ductus, which is then securely ligated (Fig. 14.5). Some
favor using a 5-0 or 6-0 Prolene taking occasional adventitial bites circumferentially around the ductus to secure
the tie. A purse-string suture of 4-0 Prolene may be placed between the ligatures to secure complete occlusion of
the ductus (Fig. 14.5, inset).
FIG. 14.1 Surgical anatomy of the ductus arteriosus. A: This incision line is used if the vagus nerve is to be
retracted medially. B: This incision line is used if the vagus nerve is to be retracted laterally.
Соседние файлы в папке Библиотека им академика М.И. Перельмана