Evaluation and treatment of carotid stenosis in open-heart surgery patients.

Indications for identification and treatment of extracranial carotid artery disease in candidates for open-heart surgery (OHS) remain unsettled. We evaluated the efficacy of OPG-GEE screening and our nonrandomized use of carotid endarterectomy in 2312 OHS patients from 1975 to 1989. Data was analyzed using the chi 2 squared and Fisher's exact tests. OPG was performed in 1602/2312 (69%) of the patients. OPG was positive in 122/1602 patients (7.6%) and negative in 1480/1602 (92.4%) patients. Of the patients with positive OPG, 31 patients had insignificant carotid bifurcation disease, 32 patients had total internal carotid artery occlusion, and 59 patients had operable carotid bifurcation lesions. Selective use of angiography identified an additional 8 patients with operable carotid bifurcation lesions (total 67, 33 symptomatic and 34 asymptomatic). Overall stroke rate for 2312 patients was 40/2312 (1.7%) [30 day mortality rate 60/2312 (3.2%)]. Stroke incidence was significantly increased (P < 0.01) in patients with a positive OPG, 8/122 (6.60%) vs those with negative OPG (23/1480, 1.6%). However, it was most marked in patients with operable bifurcation lesions (6/67, 9.0%). Stroke was not increased in patients with carotid occlusion or positive OPG without significant carotid bifurcation disease (2/63, 3.20%). Carotid endarterectomy in patients with operable bifurcation lesions was associated with a decreased (P < 0.05) stroke rate after OHS (1/44, 2.30% vs 5/23, 21.7%). Our data suggests identification of significant carotid disease and carotid endarterectomy will decrease stroke after OHS.

Cardioplegic arrest of the myocardium with calcium blocking agents.

This study was designed to compare the effects of the calcium slow channel blocking agents verapamil (0.15 mg/kg), diltiazem (0.15 mg/kg), and nifedipine (50 micrograms/kg) on the myocardium after global ischemia and reperfusion in the in situ canine model. Animals were subjected to 120-min normothermic global ischemia, followed by 45-min reperfusion. Cardioplegic arrest of the myocardium was achieved by administering one of the three calcium antagonists in a multidose fashion. Superior preservation (p less than 0.01) of left ventricular (LV) systolic function was achieved in group I (verapamil cardioplegia). dP/dt, at an intraventricular balloon volume of 25 cc, was 83% of control after reperfusion in group I. Group II (diltiazem) and group III (nifedipine) achieved only 55 and 63% of their preischemic dP/dt values. LV chamber stiffness was increased in hearts protected with nifedipine. The exponential constant m was increased from 0.04 +/- 0.01 to 0.08 +/- 0.01. Coronary blood flow after reperfusion increased from 120 to 184 cc/100 gr/min in group I (p less than 0.01). The hyperemic response in group III was negligible. The O2 consumption of the reperfused myocardium was not significantly altered in any of the treatment groups. Lactate metabolism during ischemia and after reperfusion was similar in all groups. ATP values were markedly reduced in all groups (p less than 0.05). Immediately after ischemia, ATP was 50, 28, and 44% of control in group I, II, and III, respectively. The excellent preservation of systolic function and a physiologic hyperemic response by verapamil could not be correlated with improved preservation of high-energy compounds or with significant changes in myocardial O2 consumption.(ABSTRACT TRUNCATED AT 250 WORDS)

Tracheal autograft revascularization.

A series of experiments were conducted to assess the possibility of revascularizing tracheal homografts with an omental pedicle flap. Three different experiments were performed. In Group I (N = 4) a ten-ring tracheal allograft was embedded into the greater omentum of a recipient animal for 30 days. At reexploration these four allografts were found to have been transformed into a tube consisting mainly of connective tissue. To provide more collateral circulation, we immediately reanastomosed an eight-ring tracheal autograft in Group II animals (N = 7). Collateral blood supply was possibly available from the surrounding mediastinal tissues, the recipient trachea, and the transposed omental graft. Tracheal malacia and loss of rings 4,5, and 6 was a consistent finding and cause of death. A third group of animals (Group III) underwent a similar operation with the addition of free bone grafts being applied to the external surface of the autograft to impede significant tracheal stenosis. The long-term results and the findings when the animals were put to death were the same as in Group II. We conclude that the omental pedicle graft cannot sustain chondrocyte viability. Thus a reliable method for revascularization of a tracheal transplant remains to be found.

Pharmacologic support of the myocardium following aortocoronary bypass surgery: a comparative study.

To evaluate the hemodynamic effects of simultaneous nitroglycerin and epinephrine infusion following aortocoronary bypass surgery, 16 patients were monitored and studied in the early postoperative period. All patients were given intravenous nitroglycerin, epinephrine, epinephrine combined with nitroglycerin, and dobutamine in a randomized manner. The dose of pharmacologic agent was gradually increased to achieve the required circulatory response. The measured variables included heart rate (HR), central venous pressure (CVP), arterial blood pressure (BP), pulmonary artery pressure (PA), pulmonary artery wedge pressure (PAWP), cardiac output, and arterial and venous oxygen saturations. A nitroglycerin infusion at 1.1 +/- 2 micrograms/kg/min caused the PAWP to decrease by 37% (P less than or equal to .005). All other parameters were not significantly different from control. Epinephrine at a dose of 0.06 +/- 0.02 micrograms/kg/min increased the mean blood pressure by 21% (P less than or equal to .005). The rate-pressure product (RPP) and PAWP were elevated by 18% and 12%, respectively (P less than or equal to .005). Cardiac index, however, was not increased. When nitroglycerin was added to the epinephrine infusion, a PAWP increase was not seen. Also the right ventricular stroke work index was increased by 23% (P less than or equal to .01), and the left ventricular stroke work index increased by 21% (P less than or equal to .01). Dobutamine 4.8 +/- 1.0 micrograms/kg/min caused ventricular stroke work indexes to increase significantly (P less than or equal to .005). The CVP and PAWP were unchanged with this mode of therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of vitamin D3 on imaging of experimental myocardial infarcts with technetium-99m pyrophosphate: further studies of the role of calcium.

We previously found that a pulse dose of vitamin D3 increased [99mTc]PPi uptake by rat myocardial necrosis. Vitamin D3 raised serum and lesion [Ca] but not, we now report, lesion [Fe]. We now also report that D3 increased [99Tc]PPi uptake by myocardial infarcts (L) in dogs from 0.345 +/- 0.007% administered (kg) dose/g in controls to 0.703 +/- 0.089 in treated (p less than 0.025). Vitamin D3 decreased uptake by dog bone (B) as measured in rib and sternum, increasing L/B from 1.10 +/- 0.23 to 2.30 +/- 0.52 (p = 0.06) X (L) was positively, (p less than 0.005) and uptake by sternum was negatively (p less than 0.05) correlated with serum [Ca] and [P], respectively. Scintigrams graded by a "blinded" observer, showed 4+, 4+, and 3+ infarcts, respectively, in three D3-treated dogs, and 2+, 2+, and 1+, respectively, in three untreated. One untreated and one treated dog were negative; the latter showed the least response to D3 in serum [Ca] and [99mTc] in tissue samples. Vitamin D3 can increase L/B in dogs, enhancing scintigraphic images.

Comparison of ceftriaxone and cefazolin prophylaxis against infection in open heart surgery.

One hundred four patients undergoing elective open heart surgery were enrolled in a prospective, double-blind trial comparing prophylaxis against infection using a single 1 g dose of ceftriaxone and seven doses of cefazolin. Patients in both groups had similar risk factors for infection. The likelihood of achieving a tissue concentration in excess of the minimal inhibitory concentration for Staph. aureus was significantly greater with ceftriaxone in atrial appendage (p less than 0.001), muscle (p less than 0.01), and bone (p less than 0.01) than with cefazolin. The serum half-life of ceftriaxone was approximately 15.7 hours. All 49 serum samples obtained 18 to 24 hours after delivery of ceftriaxone and 26 of 33 samples obtained 40 to 48 hours after delivery had drug concentrations in excess of 3.1 micrograms/ml, the mean minimal inhibitory concentration for isolates of Staph. aureus. Early and late infectious complications were infrequent and occurred at similar rates in both groups. Neither drug was associated with significant toxicity. A single 1 g dose of ceftriaxone was as effective and safe as multiple doses of cefazolin and demonstrated superior tissue penetration.

Preparation of venous allografts. A comparison of techniques.

In order to evaluate alternate techniques of preparing veins for use as homografts, 102 femoral veins were harvested from adult mongrel dogs. The veins were treated in four different ways, then transplanted into recipient animals bypassing their ligated femoral arteries. Group I--24 veins (6 cm each) were harvested and immediately transplanted. Group II--24 veins were stored in 15% dimethyl sulfoxide (DMSO) solution at -120 C for 21 days prior to transplantation. Group III--26 veins were stored for 21 days in plasminate solution at -60 C prior to use as allografts. Group IV--28 veins were stored in 0.5% gluteraldehyde solution for 21 days prior to implantation. Animals were randomly sacrificed at 1-month, 2-month, 6-month, and 12-month intervals. Patency of the transplant was determined weekly by ultrasound. Specimens were sent for light and scanning electron microscopy at the time of harvest, prior to implantation, and at sacrifice. Endothelial damage was graded on a scale of 0-16. Veins in Group II had a significantly higher patency rate (68% at 1 year) than Group III (35%) and Group IV (11%) (p less than 0.05). The intimal layer of all patent vessels was replaced by an organized mural thrombus. Partial endothelialization of the luminal surface was most prevalent in Group II. Intimal damage related to storage technique was significant in Group III (p less than 0.01). At sacrifice, severe endothelial damage was present in all groups (p less than 0.01). In conclusion, veins stored in 15% dimethylsulphoxide (DMSO) solution at -120 C have immunologic and physical characteristics that yield patency rates acceptable for clinical use when autogenous tissue is not available.

Verapamil cardioplegia: improved myocardial preservation during global ischemia.

To determine whether the calcium antagonist verapamil can produce satisfactory myocardial preservation during global ischemia, we studied three groups of eight dogs. Serial left ventricular biopsy specimens were taken for adenosine triphosphate and creatine phosphate content. Arterial and coronary sinus blood samples were obtained for lactate and oxygen content determination prior to ischemia, immediately after the ischemic interval, and after a 30 minute reperfusion period. Starling and isovolumetric ventricular function curves were determined prior to ischemic arrest and after 45 minutes of reperfusion. All animals were systemically cooled to 25 degrees C, and the aorta was clamped for 120 minutes. Group I had a potassium cardioplegic solution (30 mEq/L) chilled to 4 degrees C and injected into the aortic root. The initial dose was 200 ml and an additional 100 ml was infused at 20 minute intervals. Group II had a solution containing verapamil (0.15 mg/kg/L), diluted in Ringer's solution (4 degrees C), injected into the aortic root. The initial and subsequent doses were as in Group I. Group III received the same solution as Group II, but at room temperature. Alterations in lactate metabolism were not significantly different in any of the three treatment groups. A reduction in oxygen consumption was seen in Group III, but was not found to be statistically significant. However, the reduction in coronary flow at the end of reperfusion was statistically significant in Group III (p less than 0.05). Verapamil given at room temperature resulted in poor preservation of left ventricular function and high-energy stores. Verapamil combined with extreme hypothermia (Group II) provided excellent preservation of left ventricular compliance and contractility. Cold verapamil cardioplegia was superior to potassium cardioplegia for the preservation of adenosine triphosphate.

The optimal temperature for preservation of the myocardium during global ischemia.

To determine the myocardial temperature that provides maximal preservation of the heart during global ischemic arrest, five groups of dogs were studied (6 per group). In all animals, the aorta was cross-clamped for 120 minutes. Serial biopsies were done for determination of adenosine triphosphate and creatine phosphate, and study by electron microscopy. Starling curves were derived prior to cardiopulmonary bypass and 60 minutes after bypass. Mitochondrial changes were graded on a scale of 0 to 4. In the control group (Group 1), the aorta was clamped when the rectal temperature reached 25 degrees C (myocardial temperature, 18 degrees to 22 degrees C). In Groups 2, 3, 4, and 5, myocardial temperature was maintained at 6 degrees C, 10 degrees C, 14 degrees C, and 18 degrees C (all +/- 2 degrees C), respectively, by the use of systemic and topical hypothermia and repeated injections of cold cardioplegic solution into the aortic root. All groups showed a depression of left ventricular stroke work index, particularly Group 1 (no survivors), Group 2, and Group 3. The high-energy phosphate stores were well preserved in all groups except Group 1. The mitochondrial ultrastructure showed significant changes in all groups, especially Groups 1 and 5. These data indicate that satisfactory preservation of mitochondrial ultrastructure and high-energy phosphates was achieved at myocardial temperatures lower than 18 degrees C. Extreme hypothermia (Groups 2 and 3) was associated with significant reduction in ventricular function under the experimental conditions employed.

Noninvasive screening for asymptomatic carotid artery disease prior to cardiac operation. Experience with 500 patients.

Five hundred patients scheduled for cardiac operations underwent preoperative screening for asymptomatic carotid artery disease by means of the Gee ocular pneumoplethysmograph (OPG). Only patients with abnormal OPG measurements (5 mm Hg difference or greater in ophthalmic artery pressures or 0.69 or less ophthalmic artery/brachial artery pressure ratio) had cerebral angiography regardless of the presence or absence of a carotid bruit. Thirty-two patients (6.4%) were found to have carotid bruits. Nine patients had abnormal OPG measurements. Cerebral angiograms disclosed that six of these patients had significant (greater than 50%) carotid artery stenosis, and endarterectomy was performed prior to cardiac operation without incident. Nine other patients without carotid bruits had abnormal OPG measurements, and they also underwent cerebral angiography. Angiograms revealed significant carotid artery stenosis in three patients and prophylactic endarterectomy was performed. Twenty-three patients with carotid artery bruits and normal OPG measurements did not have cerebral angiography prior to the cardiac procedure. The incidence of stroke in this series of 500 patients was 0.4% (two patients). The clinical management of patients with asymptomatic carotid artery disease and coronary artery disease was facilitated by the use of noninvasive screening for the evaluation of carotid artery bruits. Patients with hemodynamically insignificant carotid disease, verified by OPG measurements, can be spared the risk and cost of cerebral angiography. Patients without clinical signs of carotid artery disease can also be identified.

Perioperative protection of the myocardium in patients with impaired ventricular function.

Seventeen patients with poor ventricular function and severe coronary artery obstruction were operated on employing hypothermic potassium cardioplegic solution for myocardial preservation. Preoperatively and postoperatively, serial hemodynamics, electrocardiograms (ECG), MB-CPK studies, and technetium pyrophosphate scans were obtained for all patients. All ECGs and scans were negative for perioperative infarction. Peak MB-CPK levels were 40 +/- 25 units per liter. Two patients had MB-CPK levels suggestive of perioperative myocardial infarction. The preoperative cardiac index was 2.8 +/- 0.8 L/min/m2 and remained the same in the perioperative period. Stroke work index and total peripheral resistance were within normal range and remained constant throughout the period of study. Three patients required epinephrine (0.5 micrograms per minute) during the first 6 hours postoperatively, and in 2 patients an intraaortic balloon was inserted prophylactically and removed on the second postoperative day. Good myocardial preservation can be achieved in patients with severe coronary artery obstruction and preexisting left ventricular dysfunction using hypothermic potassium cardioplegic solution.

Perioperative preservation of myocardial ultrastructure and high-energy phosphates in man.

To establish whether hypothermic crystalloid potassium cardioplegia given in multidose fashion provides adequate preservation of myocardial ultrastructure and high-energy phosphates, we studied 25 patients with an ejection fraction of 50% or higher who were undergoing cardiac procedures. Eight patients had three biopsy specimens taken from the left ventricular apex for determination of adenosine triphosphate (ATP) and creatine phosphate (CP). Specimens were taken immediately prior to aortic cross-clamping, immediately after the release of the aortic cross-clamp, and 30 minutes after the release of the cross-clamp. Seventeen patients had six specimens taken form the left ventricular apex at the above-stated times, three for ATP and CP determination and three additional specimens for electron microscopy. One patient had a small perioperative infarction and another patient died on the fifth postoperative day of an aortic dissection. The mitochondria on the electron microscopic specimens were graded on a scale from 0 to 4 (4 = severe changes). There was no significant difference in the mitochondrial scores. The preservation oh high-energy phosphates was less complete. ATP was reduced to 78% (3.4.2) of control and CP was reduced in the immediate postclamp period to 32% (081/2.5)of control. The difference are particularly significant if one looks at patients whose aortic cross-clamp time was 90 minutes or more (12 patients). In this group, ATP an CP preservation were 71% of control (3.33/4.60 mmoles/kg. wet weight) and 53% of control (l.48/2.81), 30 minutes after clamp removal (p equal to or less than 0.01). We conclude that hypothermic potassium cardioplegia gives excellent preservation of the myocardial ultrastructure in man. However, the preservation of high-energy phosphates with this technique is imperfect.

Parasternal intrapleural colon interposition: an alternative pathway for the colon graft.

A new pathway for the placement of the interposed colon in esophagocolonoplasty is described. In a patient with a peptic stricture and a history of previous coronary artery bypass operation and multiple thoracotomies, the interposed colon was placed in the parasternal right intrapleural space successfully. This avoided a thoracotomy as well as the areas of adhesion. Technical details are described.

Perioperative myocardial infarction: a diagnostic dilemma.

Patients undergoing coronary bypass grafting were studied for incidence of perioperative myocardial infarction (MI) using three modalities: serial electrocardiograms (ECG), serial creatine phosphokinase isoenzymes (MB-CPK), and serial technetium 99m-labeled pyrophosphate scans. A definite perioperative MI was diagnosed if the results were positive in two of the three variables studied. The perioperative infarction rate for the entire group was 8%. The operative mortality was 2.9%. Seven of 8 perioperative MIs were diagnosed by the use of scanning alone. The combination of isoenzyme and ECG analysis diagnosed 5 of 8 perioperative MIs. The MB-CPK and ECG studies were associated with a higher incidence of false-positive diagnoses than myocardial scanning. Patients with perioperative MI had a benign clinical course. Justification for performing three routine 99mTc-pyrophosphate scans on all patients undergoing aortocoronary bypass operation is still to be determined.

Technique for insertion of the intra-aortic balloon through the aortic arch.

A technique for rapid insertion of the intra-aortic balloon (IABP) through the proximal portion of the aortic arch is described. This method is beneficial in patients who require balloon support but in whom extensive aorto-femoral disease prevents the usual retrograde insertion. In these circumstances the balloon is inserted in the proximal aortic arch because multiple proximal vein grafts, ascending aorta replacement, and aortic valve surgery may make the ascending aorta an unsuitable site. The technique has been used in four patients with benefit sufficient to permit coronary artery bypass grafting with survival.

Autologous rectus sheath grafts. V. Growth in aortic grafts.

Experiments were designed to test autologous rectus sheath as a replacement for the thoracic aorta in the growing dog. Adequacy of graft function was determined by angiography at 4 month intervals; stress-strain measurements and microscopic examination were made at the time of autopsy. A 3 cm tubular graft of rectus sheath tissue was employed as an aortic graft in 13 mongrel puppies. Nine puppies (70%) were long-term survivors and were put to death between 6 and 22 months postoperatively. No deaths were due to graft failure. Angiographic studies demonstrated patency of the graft without development of pressure gradients. An increase in diameter of the aorta (21.25%) and the rectus sheath graft %22.87%) were demonstrated in all cases. During the time of observation, the compliance of the growing aorta (93,120 dynes/cm2) decreased to one fourth that of the control aortic tissue (24,800 dynes/cm2), whereas the compliance of the rectus sheath graft (547,1000 dynes/cm2) decreased to only one eighth that of the control rectus sheath (47,400 dynes/cm2). Tensile strength is maintained in both the growing aorta (4.5 x 10(7) dynes/cm2) and the rectus sheath graft (4.7 x 10(7) dynes/cm2; p less than 0.05). Microscopic examination showed no calcification, thinning, or weakness. Vascularization of the graft had occurred, with cellular proliferation and development of more than 30 lamellar-like units in the media and an adventitia-like surface.

Comparison of lactate and pyruvate during endotoxic shock.

The livers of Sprague-Dawley rats, previously injected with endotoxin, were isolated and perfused in a controlled environment with known amounts of lactate or pyruvate. Samples were taken after one hour to determine substrate utilization, content of oxidized and reduced metabolites, adenylate energy charge and reduced nicotinamide adenine dinucleotide/nicotinamide adenine dinucleotide + ratio. In this experiment, it was found that, in the group treated with endotoxin and perfused with lactate substrate, utilization and adenylate energy charge were reduced, while the concentration of reduced metabolites and reduced nicotinamide adenine dinucleotide/nicotinamide adenine dinucleotide + ratio were increased. We conclude that infusion of lactate solutions to patients in a state of shock may have an adverse effect upon cellular function.