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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3781_Библиотеки_им_академика_М_И_Перельмана
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D. C. Paneitz and J. S. Lawton
Conduit Options
• Left internal mammary artery (LIMA) is the preferred conduit for bypass to the
left anterior descending artery (LAD). It has excellent 5-year and 10-year patency
rates of 95% and 90%, respectively. The right internal mammary artery (RIMA)
has similar graft patency rates. Internal mammary artery grafts have been demonstrated to prolong survival and reduce ischemic events. These benets are
derived from the biology of the IMA which has resistance to development of
atherosclerosis due to a non-fenestrated internal elastic lamina, high intrinsic
production of vasodilators, and resistance to vasoconstriction [5, 6].
• Radial artery is preferred over saphenous vein to bypass a signicantly stenosed,
non-LAD vessel based on studies showing better long-term patency (80–95% at
5years) and improved outcomes at 10years. The radial artery has a fenestrated
internal elastic lamina, which makes it more vulnerable to atherosclerosis, and is
less resistant to vasospasm than the IMA.It is important that the radial artery be
used to bypass a signicantly stenosed vessel as competitive ow from the native
vessel can compromise the conduit patency [5, 6].
• Multiple (and total) arterial revascularization using bilateral internal mammary
arteries (BIMA) and/or radial artery has been found to have improved outcomes
including increased survival compared to single arterial revascularization. It
should be considered for most patients with only a few exceptions (poorly
controlled diabetes, obesity, poor ulnar artery compensation, or prior use for
radial access catheterization) [7, 8].
• Greater saphenous vein is the most common venous conduit. Its advantages
include ease of harvest and resistance to spasm; however, its disadvantages
include a proclivity to intimal hyperplasia, thrombosis, and graft atherosclerosis.
Ten-year patency is reported to be around 50%.
• Gastroepiploic artery is an alternative but uncommonly used arterial conduit in
the United States.
Basic Steps ofCoronary Artery Bypass Grafting (CABG)
Using Cardiopulmonary Bypass (CPB) [9]
1. Anesthesia procedures: intubation, general anesthesia, arterial line, central line,
Foley catheter with temperature probe, antibiotics
2. Positioning and preparation: supine with both arms tucked unless harvesting
radial artery, antiseptic prep from chin to ankles (and arm if radial artery
harvested)
3. Sternotomy
4. Conduit harvest: IMA, radial artery, saphenous vein (open vs endoscopic)
5. Pericardial well creation and general inspection of the heart and aorta
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6. Heparinization: bolus before conduit harvest and prior to CPB, monitor acti-
vated clotting time (ACT) level (goal >480s during CPB) throughout case
7. Aortic followed by venous cannulation: cannulate aorta with relative systemic
hypotension (SBP 90–100mmHg)
8. Dual lumen aortic root catheter placed in ascending aorta for antegrade car-
dioplegia and venting
9. Retrograde cardioplegia catheter placed in coronary sinus
10. Commencement of cardiopulmonary bypass
11. Allow mild hypothermia (32°C) while on CPB
12. Evaluation of distal targets, ordering of anastomoses, and preparation of
conduits
13. Aortic cross clamp applied: the “cross clamp time” is the period from clamp
placement to removal during which the heart is ischemic and should be minimized as much as possible
14. Administration of antegrade cardioplegia: ensure left ventricular dilatation does
not occur
15. Administration of retrograde cardioplegia with aortic root venting
16. Distal anastomoses order: inferior wall followed by distal lateral wall, proximal
lateral wall, diagonal, and LAD
17. Systemic re-warming
18. Proximal anastomoses
19. De-airing maneuvers to remove air from grafts: Trendelenburg position, lung
ination, warm retrograde cardioplegia
20. Remove aortic cross clamp
21. Remove retrograde cardioplegia catheter
22. Place epicardial atrial and ventricular pacing wires
23. Wean from CPB
24. Administer protamine to reverse heparinization
25. Remove remaining cannulas
26. Hemostasis and chest tube placement
27. Sternal closure
129
On Pump Versus Off Pump Coronary Artery Bypass
• While “On Pump CABG” (ONCAB) is the gold standard technique for surgical
coronary artery revascularization, off pump CABG (OPCAB) is performed without the use of cardiopulmonary bypass which offers some potential advantages
including the avoidance of the inammatory effects of the cardiopulmonary
bypass circuit and the ability to perform bypass without the need for a cross
clamp, which is ideal for patients with a porcelain aorta.
• Despite these advantages, OPCAB does not appear to be a better option than
ONCAB for most patients. In fact, OPCAB has been associated with decreased
survival in addition to a higher incidence of incomplete revascularization and
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D. C. Paneitz and J. S. Lawton
repeated revascularization [10]. However, this may not be the case for surgeons
who routinely perform OPCAB and are able to achieve complete revascularization [10, 11].
References
1. Roth GA, Mensah GA, Johnson CO, etal. Global burden of cardiovascular diseases and risk
factors, 1990–2019. J Am Coll Cardiol. 2020;76(25):2982–3021. https://doi.org/10.1016/j.
jacc.2020.11.010.
2. Yahagi K, Kolodgie FD, Otsuka F, et al. Pathophysiology of native coronary, vein graft,
and in-stent atherosclerosis. Nat Rev Cardiol. 2016;13(2):79–98. https://doi.org/10.1038/
nrcardio.2015.164.
3. Suarez-Pierre A, Velez A, Lawton JS. Primary coronary artery bypass surgery. In: Johns
Hopkins textbook of cardiothoracic surgery. 3rd ed. McGraw Hill/Medical. 2024.
4. Fihn SD, Gardin JM, Abrams J, etal. 2012 ACCF/AHA/ACP/AATS/PCNA/SCAI/STS guideline for the diagnosis and management of patients with stable ischemic heart disease. J Am
Coll Cardiol. 2012;60(24):e44–e164. https://doi.org/10.1016/j.jacc.2012.07.013.
5. Brescia A, Louis C, editors. TSRA review of cardiothoracic surgery. 3rd ed. Independently
Published; 2021.
6. Lawton JS, Tamis-Holland JE, Bangalore S, etal. 2021 ACC/AHA/SCAI guideline for coronary artery revascularization: a report of the American College of Cardiology/American Heart
Association Joint Committee on Clinical Practice Guidelines. Circulation. 2022;145(3):e18–
e114. https://doi.org/10.1161/CIR.0000000000001038.
7. Taggart DP, Gaudino MF, Gerry S, etal. Effect of total arterial grafting in the arterial revascularization trial. J Thorac Cardiovasc Surg. 2022;163(3):1002–1009.e6. https://doi.org/10.1016/j.
jtcvs.2020.03.013.
8. Lawton JS.Why not give all patients the opportunity to have the benets of BITA grafting? J
Am Coll Cardiol. 2021;77(1):27–8. https://doi.org/10.1016/j.jacc.2020.11.015.
9. Lawton JS.Chapter 8: Coronary artery bypass grafting (on pump arrested). In: Cardiac surgery: technique and practice. 2024.
10. Gaudino M, Benedetto U, Bakaeen F, etal. Off- versus on-pump coronary surgery and the
effect of follow-up length and surgeons’ experience: a meta-analysis. J Am Heart Assoc.
2018;7(21):e010034. https://doi.org/10.1161/JAHA.118.010034.
11. Lawton JS.Off-pump coronary artery bypass grafting: do it often, do it well, and do it completely—or don’t do it at all. J Thorac Cardiovasc Surg. 2016;152(5):1331–2. https://doi.
org/10.1016/j.jtcvs.2016.07.009.
12. BARI Investigators. The nal 10-year follow-up results from the BARI randomized trial. J Am
Coll Cardiol. 2007;49(15):1600–6. https://doi.org/10.1016/j.jacc.2006.11.048.
13. Farkouh ME, Domanski M, Sleeper LA, et al. Strategies for multivessel revascularization
in patients with diabetes. N Engl J Med. 2012;367(25):2375–84. https://doi.org/10.1056/
NEJMoa1211585.
14. Park SJ, Ahn JM, Kim YH, etal. Trial of everolimus-eluting stents or bypass surgery for coronary disease. N Engl J Med. 2015;372(13):1204–12. https://doi.org/10.1056/NEJMoa1415447.
15. Velazquez EJ, Lee KL, Jones RH, et al. Coronary-artery bypass surgery in patients with
ischemic cardiomyopathy. N Engl J Med. 2016;374(16):1511–20. https://doi.org/10.1056/
NEJMoa1602001.
16. Stone GW, Kappetein AP, Sabik JF, etal. Five-year outcomes after PCI or CABG for left
main coronary disease. N Engl J Med. 2019;381(19):1820–30. https://doi.org/10.1056/
NEJMoa1909406.
11 Management ofCoronary Artery Disease
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17. Thuijs DJFM, Kappetein AP, Serruys PW, etal. Percutaneous coronary intervention versus
coronary artery bypass grafting in patients with three-vessel or left main coronary artery disease: 10-year follow-up of the multicentre randomised controlled SYNTAX trial. Lancet.
2019;394(10206):1325–34. https://doi.org/10.1016/S0140- 6736(19)31997- X.
18. Maron DJ, Hochman JS, Reynolds HR, et al. Initial invasive or conservative strategy for
stable coronary disease. N Engl J Med. 2020;382(15):1395–407. https://doi.org/10.1056/
NEJMoa1915922.
19. Holm NR, Mäkikallio T, Lindsay MM, etal. Percutaneous coronary angioplasty versus coronary artery bypass grafting in the treatment of unprotected left main stenosis: updated 5-year
outcomes from the randomised, non-inferiority NOBLE trial. Lancet. 2020;395(10219):191–9.
https://doi.org/10.1016/S0140- 6736(19)32972- 1.
20. Park DW, Ahn JM, Park H, etal. Ten-year outcomes after drug-eluting stents versus coronary
artery bypass grafting for left Main coronary disease. Circulation. 2020;141(18):1437–46.
https://doi.org/10.1161/CIRCULATIONAHA.120.046039.
21. Fearon WF, Zimmermann FM, De Bruyne B, etal. Fractional ow reserve–guided PCI as
compared with coronary bypass surgery. N Engl J Med. 2022;386(2):128–37. https://doi.
org/10.1056/NEJMoa2112299.
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Chapter 12
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Mechanical Complications ofMyocardial
Infarction
TravisD.Hull andGeorgeTolis Jr
Introduction
• Mechanical complications of acute myocardial infarction (MCAMI) include
acute mitral regurgitation (AMR) due to papillary muscle rupture, ventricular
septal defect (VSD), free wall rupture (FWR), and left ventricle (LV) aneurysm
and pseudoaneurysm (Table12.1).
• Risk factors for these complications in patients who present with AMI include
late hospital presentation, large infarcts, poor tissue reperfusion after percutaneous intervention (PCI) [1], and patient characteristics including older age, female
sex, rst AMI, or history of heart failure or chronic kidney disease [2, 3].
• The incidence of these mechanical complications is declining largely due to
improving reperfusion techniques including the systematic adoption of early percutaneous revascularization strategies. However, the mortality associated with
them is high and directly proportional to the amount of time it takes for them to
be recognized and treated [4].
• Severely decompensated patients can temporarily be stabilized by supporting
end-organ perfusion with mechanical support including an intra-aortic balloon
pump (IABP) or extracorporeal membrane oxygenation (ECMO), but surgical
repair, usually in the emergent setting, is required to prevent patient death.
T. D. Hull
Division of Cardiothoracic Surgery, Massachusetts General Hospital, Boston, MA, USA
e-mail: thull1@partners.org
G. Tolis Jr (*)
Division of Cardiothoracic Surgery, Brigham and Women’s Hospital, Boston, MA, USA
e-mail: gtolis@bwh.harvard.edu
Switzerland AG 2024
J. P. Bloom, T. M. Sundt (eds.), Cardiac Surgery Clerkship, Contemporary
Surgical Clerkships, https://doi.org/10.1007/978-3-031-41301-8_12
133© The Author(s), under exclusive license to Springer Nature
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Table 12.1 Mechanical complications of acute myocardial infarction
Incidence/
MCAMI
Acute MR
secondary
to PM
rupture
Ventricular
septal
defect
Free wall
rupture
Abbreviations: MCAMI mechanical complication of AMI, AMI acute myocardial infarction, MR
mitral regurgitation, TTE transthoracic echocardiography, TEE transesophageal echocardiography,
PMR papillary muscle rupture, IABP intra-aortic balloon pump, RHC right heart catheterization,
RA right atrium, PA pulmonary artery, tMCS temporary mechanical circulatory support, SCD sud-
den cardiac death, ECMO extracorporeal membrane oxygenation
mortality Presentation Diagnosis
0.05–0.26%
10–40%
0.3%
80% with
medical
management,
40% with
surgical
management
Most
common
MCAMI,
unknown
incidence,
usually SCD
>35%
mortality with
surgery
3–5days
after AMI
Cardiogenic
shock,
pulmonary
edema
3–5days
after AMI
Varied
presentation
from
murmur to
shock
3–5days
after AMI
Cardiogenic
shock with
signs of
tamponade
TTE demonstrating
severe MR
TEE more sensitive
for partial PMR
Echocardiography
is diagnostic
RHC shows step
up in oxygenation
between the RA
and PA
High clinical
suspicion, signs
and symptoms of
cardiac tamponade,
bedside
echocardiography
T. D. Hull and G. Tolis Jr
Medical
management
Reduction of
LV afterload
with
pharmacologic
agents
(nitroglycerin)
or mechanical
support (IABP)
Afterload
reduction with
IABP ± tMCS
to decompress
the LV
Not applicable.
ECMO can be
utilized in the
event of
cardiovascular
collapse as a
bridge to the
operating room
Surgical
management
Emergent
(within 24h)
mitral valve
replacement
Emergent to
urgent repair
as dictated
by degree of
cardiogenic
shock
Immediate
emergent
surgical
repair
Evaluation
Presentation
• Most patients with MCAMI present in some degree of shock with evidence of
end-organ malperfusion from deranged pump function (i.e., cardiogenic shock).
• The differential diagnosis in MCAMI is broad, as it includes other causes of
shock including hemorrhagic, hypovolemic, and septic shock as well as a broad
array of etiologies for cardiogenic shock including acute pulmonary embolism,
aortic dissection, valvular pathology, tamponade, stress-induced cardiomyopathy, or AMI without a mechanical complication.
• A focused history and physical exam should be performed to elucidate risk fac-
tors for MCAMI including signs or symptoms of recent or ongoing MI such as
chest pain. A personal or family history of coronary artery disease and peripheral
vascular disease are additional important clues. Findings on physical exam
include a new murmur, pulse irregularities, JVD, or systemic signs of
malperfusion.
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135
Diagnostic Studies
• The initial study of choice is a bedside transthoracic echocardiogram (TTE) to
assess the pericardial space, pump function and geometry, ventricular loading
conditions, valvular pathology, outow tract obstruction, and regional wall
motion abnormalities.
• Additional studies such as CT scan with angiography of the chest, abdomen, and
pelvis can be useful, particularly in ruling out extra-cardiac explanations for a
presentation of shock.
Initial Management
• If MCAMI is not recognized in a timely manner, diminished cardiac output leads
to multi-system organ failure and death, which can only temporarily be curtailed
by the institution of inotropes, IABP, and temporary mechanical circulatory
support.
• Therefore, the role of the cardiac surgeon in the multi-disciplinary team is imper-
ative, particularly in expediently diagnosing and managing patients with MCAMI.
• Denitive treatment of MCAMI is surgical and includes correction of the struc-
tural issue that has occurred secondary to AMI and has resulted in a hemodynamically signicant mechanical complication.
• Concomitant surgical revascularization by coronary artery bypass is often of util-
ity but should be assessed on a case-by-case basis and guided by pre-operative
coronary angiogram.
Acute Mitral Regurgitation
Pathogenesis
• The mitral valve (MV) is supported by the anterolateral (AL) and posteromedial
(PM) papillary muscles.
– The AL papillary muscle has a dual blood supply from the left anterior
descending and left circumex coronary artery.
– The PM papillary muscle has a single blood supply from the right coronary
artery or left circumex artery, depending on dominance.
– Therefore, PM papillary muscle rupture (PMR) is signicantly more common
and is associated with inferior (RCA) or lateral (left circumex) infarction.
Diagnosis
• Patients typically present 3–5days after AMI with evidence of acute pulmonary
edema that rapidly progresses to cardiogenic shock.
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• On exam, a systolic murmur may be audible at the left lower sternal border radi-
ating to the axilla.
• Diagnosis is made with echocardiography, which shows severe, often
eccentric MR.
• Although TTE is readily available and non-invasive, a partial PMR can be missed
with this modality, and therefore, sensitivity is improved by transesophageal
echocardiography (TEE).
T. D. Hull and G. Tolis Jr
Management
• Medical management is largely temporizing to improve hemodynamics and tis-
sue perfusion due to cardiogenic shock.
• Mechanical circulatory support is used in up to 70% of cases [5, 6].
– IABP decreases afterload, and thus, the regurgitant volume, in addition to
augmenting cardiac output [7].
• Acute MR secondary to PMR is a surgical emergency.
– Typically, chordal-sparing MV replacement is performed, although MV repair
may be an acceptable alternative in some hemodynamically stable patients
with a partial PMR [8, 9].
– Bioprosthetic or mechanical valves can be utilized, with the latter being asso-
ciated with better long-term, symptom free survival in younger patients [10].
• Revascularization with coronary artery bypass grafting (CABG) should be con-
sidered in patients with PMR, although a clear benet for concomitant CABG
targeting the inferior left ventricular wall at the time of MVR has not been clearly
demonstrated.
• Only 38–58% of patients with acute severe MR from PMR are offered surgery,
likely owning to a patient population with advanced age and signicant comorbidities who deteriorate rapidly pre-operatively. In patients who are not surgical candidates due to prohibitively high risk, percutaneous edge-to-edge MV
repair with MitraClip can be considered [11].
Post-infarction Ventricular Septal Defect
Pathogenesis
• MCAMI VSDs are characterized as anterior or posterior based on the location of
the perforation on the intraventricular septum. This correlates with which coronary artery is occluded and is important in planning the surgical approach.
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– Infarcts in the LAD territory are more common and generally result in ante-
rior and apical VSD.Most occur in the distal half of the septum.
– Posterior VSDs are caused by inferior infarcts and are often accompanied by
RV dysfunction, particularly when the proximal RCA is occluded, which is
often accompanied by MR from ischemic tethering of the MV and more complex VSDs [12]. Most occur in the proximal half of the septum.
137
Diagnosis
• Patients typically present 3–5days after a transmural MI with signs of heart fail-
ure ranging from dyspnea from pulmonary venous congestion to decompensated
cardiogenic shock due to left-to-right shunting and overload of the pulmonary
circulation.
• A pansystolic murmur is heard at the left lower sternal boarder.
• Echocardiography is the gold standard for diagnosis and can characterize the size
and location of the VSD to aid in surgical planning.
• Right heart catheterization can aid in diagnosis by showing a step up in oxygen-
ation between the right atrium and pulmonary artery, but is not necessary.
• Coronary angiography is helpful during initial ischemic presentation as a guide
to planning concomitant revascularization.
Management
• Surgical intervention is the standard of care as medical management alone is
associated with 80% mortality at 30days [13]. Hemodynamically stable patients
should undergo coronary angiography followed by urgent surgery.
– Despite operative intervention, mortality approaches 40%.
• In hemodynamically unstable patients, pre-operative temporizing measures
include IABP and VA-ECMO.
– An IABP affords afterload reduction to decrease left-to-right shunting and is
utilized in 65–80% of patients [14, 15].
– VA-ECMO may be utilized in patients with multi-organ failure to allow for
end-organ recovery before denitive surgical intervention.
• In patients with multi-vessel disease, the rst step in surgical intervention
includes coronary revascularization utilizing saphenous vein for the bypass graft
while on cardiopulmonary bypass. The coronary artery supplying the ruptured
septum should not be bypassed unless there is an apical VSD due to LAD occlusion proximal to the rst septal perforator.
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T. D. Hull and G. Tolis Jr
Surgical VSD Repair
• Anterior VSDs are repaired with a ventriculotomy parallel to the LAD.
• Posterior VSD are repaired with a ventriculotomy parallel to the posterior
descending artery in the infarcted posterior wall of the LV (Fig.12.1).
• The VSD is repaired with a patch constructed from pericardium or synthetic
material using pledgetted mattress or running sutures placed in non-infarcted
myocardium.
• Specic techniques for patch repair included primary repair via the Daggett
repair or infarct exclusion via the David exclusion technique. Both techniques
utilize a pericardial patch. In the Daggett repair, this patch bridges the VSD by
xation to the distal end of the ruptured IVS and free wall of the LV with interrupted, pledgetted mattress sutures. In the David repair, the patch is utilized to
exclude the left ventricular side of the septum from the mitral annulus to the
anterolateral wall of the LV. The ventriculotomy is then closed in two layers
utilizing a buttress of pericardium or felt. In recent years, the David technique
has largely replaced the Daggett technique due to its relative technical simplicity
and proven reproducibility.
• True apical VSDs can be repaired by amputating the apex and closing it primar-
ily. Some authors have reported successful case studies with this technique without utilizing cardiopulmonary bypass.
Fig. 12.1 Posterior
post-infarction VSD.The
VSD has been exposed by
a ventriculotomy made
parallel to the posterior
descending artery (PDA),
looking into the left
ventricle, through the large
VSD and into the right
ventricle. The apex of the
heart is retracted cephalad
and marked by the pledget
in the bottom right of the
photo
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