Intraoperative Angiography to Assess Graft Patency
`After Minimally Invasive Coronary Bypass
`James A/Goldstein, MD, Robert D.'Safian, MD, Darius Aliabadi, MD,
`William W.1 O'Neill, MD, Francis L/ Shannon, MD, Joseph'Bassett, MD, and
`Marc Sakwa, MD
`i Division of Cardiology, William Beaumont Hospital, Royal Oak, Michigan j
`
`Background. Intraoperative angiography was per­
`formed to confirm graft patency immediately after mini­
`mally invasive coronary bypass operations.
`Methods. In 26 patients who had internal mammary
`artery grafting, intraoperative coronary angiography was
`performed with a portable digital fluoroscope.
`Results. High-resolution angiograms were obtained in
`all cases, Angiography documented vasospasm of the
`graft or native vessel in 9 patients (graft in 3, native in 2,
`graft and native in 4 others), which responded promptly
`to intracoronary vasodilators in all. Angiography identi­
`fied technically unsuspected and clinically silent fixed
`stenoses (>50%) in 11 patients, attributable to graft
`kinking in 2, anastomotic obstruction in 6 (total occlusion
`
`in 4), and stenosis of the left anterior descending artery
`just distal to the anastomosis in three cases (total occlu­
`sion in one). In 9 of 11 patients, fixed stenoses were
`sufficiently severe to warrant intraoperative intervention
`by surgical revision in = 5) or angioplasty via the graft
`(// = 4).
`Conclusions, Intraoperative angiography after mini­
`mally invasive coronary artery bypass operations can
`immediately identify dynamic and fixed obstructions
`and facilitate their prompt treatment, thereby ensuring
`that each patient leaves the operating room with an
`optimal surgical result.
`(Ann Thorac Surg 1998;66:1978-32)
`© 1998 by The Society of Thoracic Surgeons
`
`Minimally invasive coronary artery bypass grafting
`
`a standard fixed cardiac imaging system facilitates per­
`(MINICAB) performed on the beating heart po­
`formance of intraoperative angiography [22], but this
`tentially allows patients to avoid sternotomy and elimi­
`approach is relatively expensive and might impose sub­
`nates complications associated with heart-lung bypass,
`stantial equipment space demands, We recently demon­
`advantages that could translate into less morbidity, more
`strated the feasibility of performing high-resolution cor­
`rapid recovery, and reduced costs 11-18], However, com­
`onary angiography using an inexpensive commercially
`pared v\dth coronary revascularization on the arrested
`available portable digital fluoroscopic system [23, 24],
`heart, operations on the beating heart are technically
`The present study was designed to demonstrate the
`more challenging. Not surprisingly, postoperative angio­
`feasibility of performing intraoperative angiography with
`graphic studies show graft compromise in 5% to 20% of
`a high-resolution mobile imaging system, to assess graft
`patients [3, 5, 6, 9, 11-17], in some cases necessitating
`patency immediately after MINICAB,
`reoperation. In fact, graft compromise is of sufficient
`concern to warrant testing to confirm procedural results,
`including performance of routine early postoperative
`coronary angiography in some institutions [11, 14,19-21],
`At present, early angiography after MINICAB is per­
`formed in a standard fixed cardiac catheterization labo­
`ratory either immediately [11], or 1 to 3 days postopera-
`tively ]14j. We reasoned that intraoperative angiography
`would provide instantaneous documentation of graft
`patency and facilitate prompt surgical or percutaneous
`revision of compromised grafts. This strategy would also
`avoid the logistic burdens and time delays inherent in
`transferring patients from the operating room to the
`catheterization laboratory and potentially preclude the
`need for reoperation. Equipping an operating room with
`
`Methods
`Operative Procedure
`Patients scheduled for MINICAB were screened to ex­
`clude excessive risk for contrast dye toxicity, including
`renal insufficiency, congestive heart failure, and allergies
`to contrast media. Informed consent was obtained from
`all patients. All patients were treated preoperatively with
`aspirin (325 mg four times daily). The goal of anesthetic
`management was early extubation. Short-acting narcot­
`ics supplemented by propofol or isoflurane were used.
`Subarachnoid morphine was administered preopera­
`tively to minimize postoperative pain, Patients were
`monitored by measurement of radial artery pressure and
`by electrocardiographic limb leads. An 8- to 10-cm tho­
`racotomy incision was made over the third or fourth
`costal cartilage, and the entire costal cartilage was ex­
`cised. The internal mammary artery (IMA) and its bundle
`
`0003-4975/98/,519.00
`P1I S0003-4975(98)01235-'t
`
`Accepted for publication June 2, 1998,
`Address reprint requests to Dr Goldstein, Division of Cardiology, William
`Beaumont Hospital, 3601 W 13 Mile Rd, Royal Oak, Ml ( 48073-6769)
`(e-mailfjgoldstein@beaumont.edu).
`
`© 1998 by The Society of Thoracic Surgeons
`Published by Elsevier Science Inc
`
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`.Vn„ Mi ora c Surg
`t99.‘i;|56:197S-82
`
`GOLDSTEIN ET AL 1979
`INTRAOPERATIVE ANGIOGRAPY DURING MINICAB
`
`were identified, the pleura opened, and the pericardium
`incised longitudinally. The native target coronary artery
`was identified and explored for accessibility and quality.
`The IMA was then dissected from the second costal
`cartilage to the fifth intercostal space, and heparin was
`administered intravenously (1.5 mg per kilogram of body
`mass). The IMA was clamped, ligated, divided, and
`tested for flow. Verapamil (250 p.g/mL) was applied
`externally or injected into the IMA. The target vessel was
`encircled with tapes on either side of the planned anas­
`tomotic site and stabilized with either a two-prong in­
`strument or stabilizing platform retractor (Cardiothoracic
`Systems, Cupertino, CA, or US Surgical Systems, Nor­
`walk, CT). After slowing the heart rate to 38 to 45 beats
`pei minute by intravenous beta-blockers, an end-to-side
`anastomosis was done using continuous sutures of 8-0 or
`7-0 1’rolene (Ethicon, Somerville, Nf). A dry operative
`field was maintained by continuous insufflation of carbon
`dioxide. After the anastomosis was completed, the tapes
`and IMA clamp were removed.
`
`Intraoperative Angiography
`The portable imaging system (Digital Mobile C-Arm,
`Scries 9600; OEC Medical Systems, Salt Lake City, UT) is
`a commercially available digital x-ray imaging system
`specifically modified for coronary imaging [23, 24]. The
`pulsed fluoroscopic system is capable of 30 frames per
`second dynamic acquisition and playback. Digital images
`can be viewed in real time or as still images, and can be
`permanently copied onto 3.5-inch high-density computer
`disks or ‘/a-inch videotape for long-term storage. Modifi­
`cations that facilitate coronary angiography include a
`big-C configuration of the C-arm (characterized by addi­
`tional 7-inch depth over conventional portable C-arms),
`to allow easier positioning of the x-ray table and greater
`range of angiographic angles. To optimize image quality
`and facilitate obtaining arrgulated views, a low-
`attenuation (high-resolution) carbon fiber topped fluoro­
`scopic surgical table was used (Stifle-Beta Medical Sys­
`tems, Akron, OH).
`
`Angiography of the Internal Mammary Artery
`Alter anastomosis was completed but before closure of
`the thoracotomy incision, graft angiography was per­
`formed using femoral or radial arterial access. The IMA
`was selectively engaged with a preformed 5- or 6F IMA
`catheter, and angiography was performed in right and
`left anterior oblique and lateral projections. Angiography
`was performed before and after administration of intra-
`coronary nitroglycerin (200 mg/niL), verapamil
`(250 mg/raL), or both. If the IMA graft and native vessel
`were patent with excellent flow, the catheter was re­
`moved and protamine was given. If angiography showed
`a stenosis of greater than 90% unresponsive to vasodila­
`tors, then surgical revision or intraoperative percutane-
`°u.s transluminal coronary angioplasty was performed,
`using a 6F left IMA guiding catheter, a 0.014-inch high-
`torque floppy wire, and appropriate balloon dilation
`catheters. In all such cases, repeat angiography was
`
`performed to ensure that each patient left the operating
`room with an optimal surgical result.
`
`Data Analyses
`Adverse clinical events included intraoperative or post­
`operative revascularization (surgical revision, percutane­
`ous transluminal coronary angioplasty, or conversion to
`routine bypass), in-hospital ischemia, myocardial infarc­
`tion, congestive heart failure, stroke, or death. Time to
`extubation and length of stay were recorded. Angiograms
`were analyzed by two experienced reviewers according
`to previous techniques [23, 24]. The IMA graft, anasto­
`moses, and native vessel were analyzed for patency and
`flow. Spasm was defined as a stenosis greater than 50% of
`that improved after administration of intracoronary va­
`sodilators. Fixed lesions were defined as stenoses greater
`than 50% unresponsive to intracoronary vasodilators
`analyzed by quantitative angiography using electronic
`calipers. Continuous variables are expressed as mean ±
`standard deviation, and dichotomous variables are re­
`ported as frequency.
`
`Results
`We performed MINICAB in 26 patients between October
`1996 and November 1997. Left internal mammary artery
`grafts were placed to the left anterior descending artery
`in 24 patients, and right internal mammary artery to the
`right coronary' artery in 2 others. One patient underwent
`combined (hybrid) intraoperative revascularization in
`which successful MINICAB of the left internal mammary
`artery and left anterior descending artery' was confirmed
`by angiography and followed by successful percutaneous
`stenting of a stenosis in the right coronary artery using
`the portable imaging system. In all cases, the surgeon
`considered the anastomosis to be successful and the graft
`patent by visual inspection. No patient had electrocar­
`diographic changes suggesting ischemia or hemody­
`namic instability.
`
`Angiographic Findings
`The IMA graft, anastomosis, and native distal target
`vessel were visualized with excellent angiographic reso­
`lution in all cases (Figs 1-4). Arterial spasm (Fig 2) was
`identified in 9 patients (35%), including IMA spasm alone
`in 3 (compromised flow in 1), native vessel spasm alone
`in 2 patients (1 with impaired flow'), and spasm involving
`the IMA and native vessel in 4 patients (1 with dimin­
`ished flow). Spasm was completely relieved by nitroglyc­
`erin (Fig 2) in 5 patients, but required additional vera­
`pamil in 4 others. Fixed stenoses were documented in 11
`patients (42%) (Figs 3-5). Kinking of the IMA graft (Fig 3)
`was identified in 2 of 11 pts. Anastomotic obstruction (Fig
`4) was documented in 6 patients, with total obstruction in
`4 patients and impaired flow in 5 of 6 patients. Obstruc­
`tion of the native left anterior descending artery just
`distal to the anastomosis was documented in 3 patients,
`with impaired flow in 1.
`
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`1980 GOLDSTEIN ET AL
`INTRAOPERATIVE ANCIOGRAPY DURING MINICAB
`
`Fig 3, (A) Angiogram of right internal mammary arlvnj graft dem­
`onstrates a filling defect (arrow) consistent until graft kinking con­
`firmed by visual inspection and revised by surgical repositioning,
`with repeal angiography (B) demonstrating resolution of the filling
`defect with a widely patent graft and distal vessel, although there
`urns modest spasm that responded to nitroglycerin,
`
`cases. Angioplasty failed to cross a total anastomotic
`obstruction in 1 patient, who required surgical revision.
`In 2 patients with 40% to 70% hazy stenoses, no interven­
`tion was performed.
`
`Postoperative Course
`In the immediate postoperative period, all patients were
`hemodynamically stable without electrocardiographic
`changes. There were no access site or other complications
`related to cardiac catheterization. Postoperative ischemic
`complications occurred in 1 patient in whom the intra­
`operative angiogram revealed a 70% stenosis with in­
`traluminal haziness. Acute myocardial infarction, pulmo­
`nary edema, and cardiogenic shock developed on day 3,
`and emergency angiography in the cardiac catheteriza­
`tion laboratory documented total occlusion at the distal
`anastomosis. Despite successful coronary angioplasty,
`the patient died on day 7. There were no postoperative
`complications in 25 patients. In 1 patient with a 40%
`stenosis and luminal haziness in the left anterior de­
`scending artery on intraoperative angiogram, repeal, an­
`giography on day 3 was normal. Patients were discharged
`6.3 ± 3.2 days (range, 3 lo 13 days) postoperative!}'. All
`were alive, free of angina, and hemodynamically stable.
`
`Comment
`Findings from the present study demonstrated that in­
`traoperative coronary angiography using a portable dig­
`ital fluoroscopic system documents the immediate results
`of MINICAB, avoids the logistic burdens of transporting
`patients from the operating room to the catheterization
`laboratory, and provides timely data that could influence
`intraoperative treatment and patient outcome.
`Although MINICAB offers potential benefits in the
`form of reduced complications and costs [1-18], its suc­
`cess must be measured ultimately in terms of giaft
`patency [14, 20, 21], Compared with coronary revascular­
`ization on the arrested heart, operations on the beating
`heart are technically more challenging, undoubtedly con­
`tributing to the incidence of early graft compromise
`
`Fig 1. Intraoperative angiogram documenting widely patent left in­
`ternal maununn/ artery graft (curved arrow.) and anastomosis
`(straight dark arrow! with excellent jtow into the native left tinte­
`rior descending artery (white arrows).
`
`Intraoperative Graft Revision
`The two cases of IMA kinking were relieved by simple
`surgical graft repositioning (Fig 3). Surgical revision was
`performed in 2 patients with severe anastomotic obstruc­
`tion, resulting in a widely patent graft and native vessel
`on repeal angiography. Intraoperative percutaneous
`transluminal coronary angioplasty (Fig 4) was attempted
`in 5 other patients with obstruction at the anastomotic
`site (» = 3) or left anterior descending artery just distal
`to the anastomosis (n — 1). In four of five cases, coronary
`angioplasty led to prompt relief of stenosis (99% ± 2% to
`10% ± 8%, p <0.05), with restoration of TIM! 3 flow in all
`
`13
`A
`Fig 2. (A) Patent left internal mammary artery (curved arrow)
`with marked vasospasm in the native left anterior descending mien/
`(straight arrows). (B) Relief of spasm after administration of intra-
`coronary nitroglycerin.
`
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`Ann Thorac Surg
`1998;66:1978-82
`
`GOLDSTEIN ET AL 1981
`INTRAOPERATIVE ANGIOGRAPY DURING MINICAB
`
`Fig 4. (A) Intraoperative angiogram docu­
`menting total left internal mammary ar-
`tmj obstruction (arrow). (B) Advance­
`ment of 0.014-inch coronary guideioire
`(arrow) to the site of anastomotic obstruc­
`tion, (C) Passage ofguidewirc through the
`anastomotic obstruction restored flour to
`the native left anterior descending artery
`(light arrows), but with evidence of re­
`sidual anastomotic stenosis (dark arrow).
`(D) After low-pressure balloon dilation,
`there was no residual anastomotic stenosis
`(arrow) and excellent flow.
`
`1I
`
`I"
`
`previously reported [3, 5, 6, 9, 11-17, 19-21). Although
`increasing operator experience and use of newer motion
`stabilization techniques |7, 14, 15, 25, 26] will likely
`improve surgical results, graft compromise is of sufficient
`
`IMA
`(.1)
`
`Native IMA + Nutiv* IMA Kink
`(2)
`(4)
`12)
`
`Amtitomoik'
`lf>i
`
`Native
`(.1)
`
`(Resolved with 1C dilators)
`
`v
`v
`pTCA
`Surgical
`Surgical
`(3)
`D)
`(2)
`Fig 5, Flow diagram of angiographic findings and interventions.
`(1C - intracormian/; IMA - interned mammary artery; MINI­
`CAB - minimally invasive coronary artery bypass; PTCA — percu­
`taneous transluminal coronary angioplasty.)
`
`v
`PICA
`(11
`
`concern to warrant early confirmation of procedural
`results [11, 14, 19-21]. Most patients who have elective
`surgical revascularization have adequate resting ante­
`grade or collateral flow to the target vessel and do not
`manifest resting ischemia, Therefore, it should not be
`surprising that electrocardiographic, hemodynamic, di­
`rect visualization, and Doppler graft flow measurements
`have not been sufficiently predictive of graft patency [16].
`Accordingly, the need for routine postoperative angiog­
`raphy to assess graft patency has been emphasized [11,
`14, 19-21].
`Findings from the present study confirm and extend
`those of previous reports documenting graft compromise
`by postoperative angiography in a significant number of
`patients early after MINICAB [3, 5, 6, 9, 11-17, 19-21], In
`the present study, intraoperative graft imaging was safe,
`easy to perform, and immediately identified patients
`with flow-limiting lesions that were neither technically
`suspected nor clinically apparent. Furthermore, intraop­
`erative identification of graft compromise facilitated
`timely graft revision by surgical or catheter-based inter­
`ventions, thereby ensuring a widely patent graft and
`excellent flow before chest closure. Findings from the
`present study also demonstrate the feasibility of per-
`
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`1982 GOLDSTEIN ET AL
`INTRAOPERATIVE ANGIOGRAPY DURING MINICAB
`
`Arm Thorac Sttre-
`1998;66:1978-87
`
`forming hybrid revascularization in the operating room
`using the portable imaging system, which in selected
`patients, might preclude the need to stage such proce­
`dures [27].
`Results from this observational study of our early
`MINICAB experience must be interpreted with caution,
`particularly with regard to overall patency results. We
`studied a consecutive series of patients from initial pro­
`cedures using early stabilization techniques to later ex­
`perience using more sophisticated operating platforms.
`The incidence of angiographic abnormalities observed in
`this intraoperative study is consistent with that of previ­
`ous reports of postoperative angiography, and most com­
`promised grafts occurred earliest in the learning curve of
`our operative experience. However, clinically silent ob­
`structions were observed even with later cases. We can
`only speculate as to the precise pathophysiologic mech­
`anisms responsible for the angiographic abnormalities
`observed in the present study and their natural history if
`left untreated. With the greater mechanical manipulation
`associated with operating on the beating heart, there is
`potential for vascular trauma that could induce vasocon­
`striction, intramural edema or hemorrhage, intraluminal
`thrombosis, or native vessel plaque disruption, However,
`the presence of early intraoperative angiographic abnor­
`malities does not necessarily presage coronary compro­
`mise, Further studies will be necessary to delineate the
`natural history and optimal treatment of these lesions.
`The present study was not designed to compare the graft
`patency rales or costs of surgical revascularization by
`MINICAB with those of conventional arrested-heart by­
`pass procedures. Further studies will be necessary to
`compare the outcomes, benefits, and costs of these two
`operations.
`In summary, intraoperative angiography using a por­
`table digital fluoroscopic system is easy to perform and
`provides immediate confirmation of graft patency after
`MINICAB, Intraoperative imaging identifies dynamic
`and fixed obstructions in the graft and native vessel and
`facilitates their prompt resolution by catheter-based or
`surgical interventions.
`
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