Hemodynamic effects of carbon dioxide insufflation during endoscopic vein harvesting.

BACKGROUND: A prospective study was performed assessing the hemodynamic effects of carbon dioxide (CO2) insufflation during endoscopic vein harvesting (EVH) using the Guidant Vasoview Uniport system. METHODS: Five hemodynamic and respiratory parameters (end-tidal carbon dioxide, arterial partial pressure of carbon dioxide, mean arterial pressure, mean pulmonary arterial pressure, and cardiac output), were measured in 100 consecutive patients undergoing EVH with CO2 insufflation. Data were obtained prior to commencement of EVH, 15 minutes after commencement, and 5 minutes after completion of the vein harvesting. RESULTS: No adverse hemodynamic effects were observed during CO2 insufflation. Specifically, average mean arterial pressure went from 88.77+/-9.64 to 89.13+/-8.60 to 88.24+/-8.71 mm Hg before, during, and after endoscopic vein harvesting (p = 0.291). Likewise, average mean pulmonary artery pressures were 19.76+/-4.75, 20.05+/-4.48, and 20.05+/-4.62 mm Hg (p = 0.547); and average cardiac output was 4.25+/-0.74, 4.22+/-0.73, and 4.23+/-0.69 L/min (p = 0.109) at those three intervals. Additionally, there was no evidence of significant systemic absorption of CO2 as reflected in average arterial PCO2, which remained steady at 37.42+/-5.19, 37.51+/-4.59, and 38.10+/-4.80 mm Hg (p = 0.217); and average end-tidal CO2, which was 32.10+/-3.66, 32.50+/-3.47, and 32.38+/-3.33 mm Hg (p = 0.335). In a subset of 20 patients with elevated pulmonary arterial pressure (more than 32 mm Hg), there was also no significant change in any of the parameters. CONCLUSIONS: Carbon dioxide insufflation during EVH leads to no adverse hemodynamic consequences or systemic CO2 absorption. The technique appears to be safe and well tolerated.

Activation of creatine kinase-B and phospholamban gene expression in transformed latissimus dorsi muscle: evaluation of mRNA by polymerase chain reaction.

Latissimus dorsi muscle (LDM) transformation following chronic stimulation is the critical requirement for its use in cardiac assist procedures. In order to identify one or two molecular markers that can be used to effectively monitor the LDM transformation, the modulation in the expression of creatine kinase (CK) and phospholamban (PLB) genes by semi-quantitative reverse transcriptase polymerase chain reaction (RT-PCR) was examined. Continuous in situ stimulation of left LDM was performed in four dogs for a period of 10 weeks after a vascular delay period of 2 weeks following surgery. For RT-PCR, gene-specific radiolabeled primers and equal amounts of cDNA synthesized from total RNA extracted from the LDM biopsies obtained at 4, 7, and 10 weeks of stimulation were used. A 2.6-fold increase in creatine kinase (brain type) (CK-B) mRNA was observed at transformed LDM compared to the control (P = 0.004) following 10 weeks of stimulation. On the contrary, a 30% decline was observed in creatine kinase (muscle type) (CK-M) mRNA level. An increase up to eight-fold was also observed in PLB mRNA in stimulated LDM compared to the contralateral muscle (P = 0.002). The PLB mRNA level in transformed LDM reached plateau and became comparable to that of normal heart after 7 weeks of stimulation. However, a sustained increase in CK-B mRNA level was observed until 10 weeks of stimulation. The level of beta-actin mRNA used as control remained the same in both stimulated and control samples. Thus the increase in CK-B and PLB mRNA and downregulation of CK-M mRNA in transformed LDM, demonstrated here by RT-PCR, indicate a switch from anaerobic to aerobic potential of transformed LDM along with a change towards slow-twitch phenotype and provide valuable markers to monitor the effectiveness of muscle transformation in cardiomyoplasty.

Comparative study of biological glues: cryoprecipitate glue, two-component fibrin sealant, and "French" glue.

BACKGROUND: Although biological glues have been used clinically in cardiovascular operations, there are no comprehensive comparative studies to help clinicians select one glue over another. In this study we determined the efficacy in controlling suture line and surface bleeding and the biophysical properties of cryoprecipitate glue, two-component fibrin sealant, and "French" glue containing gelatin-resorcinol-formaldehyde-glutaraldehyde (GRFG). METHODS: Twenty-four dogs underwent a standardized atriotomy and aortotomy; the incisions were closed with interrupted 3-0 polypropylene sutures placed 3 mm apart. All dogs had a 3- by 3-cm area of the anterior wall of the right ventricle abraded until bleeding occurred. The animals were randomly allocated into four groups: in group 1 (n = 6) bleeding from the suture lines and from the epicardium was treated with cryoprecipitate glue; in group 2 (n = 6) bleeding was treated with two-component fibrin sealant; group 3 (n = 6) was treated with GRFG glue; group 4 (n = 6) was the untreated control group. The glues were also evaluated with regard to histomorphology, tensile strength, and virology. RESULTS: The cryoprecipitate glue and the two-component fibrin sealant glue were equally effective in controlling bleeding from the aortic and atrial suture lines. Although the GRFG glue slowed bleeding significantly at both sites compared to baseline, it did not provide total control. The control group required additional sutures to control bleeding. The cryoprecipitate glue and the two-component fibrin sealant provided a satisfactory clot in 3 to 4 seconds on the epicardium, whereas the GRFG glue generated a poor clot. There were minimal adhesions in the subpericardial space in the cryoprecipitate and the two-component fibrin sealant groups, whereas moderate-to-dense adhesions were present in the GRFG glue group at 6 weeks. The two-component fibrin sealant was completely reabsorbed by 10 days, but cryoprecipitate and GRFG glues were still present. On histologic examination, both fibrin glues exhibited minimal tissue reaction; in contrast, extensive fibroblastic proliferation was caused by the GRFG glue. The two-component and GRFG glues had outstanding adhesive property; in contrast, the cryoprecipitate glue did not show any adhesive power. The GRFG glue had a significantly greater tensile strength than the two-component fibrin sealant. Random samples from both cryoprecipitate and the two-component fibrin glue were free of hepatitis and retrovirus. CONCLUSIONS: The GRFG glue should be used as a tissue reinforcer; the two-component fibrin sealer is preferable when hemostatic action must be accompanied with mechanical barrier; and finally, the cryoprecipitate glue can be used when hemostatic action is the only requirement.

Effect of cerebrospinal fluid drainage and/or partial exsanguination on tolerance to prolonged aortic cross-clamping.

Paraplegia as a consequence of spinal cord ischemia associated with procedures on the thoracic and thoracoabdominal aorta has been linked to the interaction of proximal hypertension with elevated cerebrospinal fluid pressure (CSFP) during aortic cross-clamping (AXC). CSFP reduction via cerebrospinal fluid (CSF) drainage is thought to significantly prolong the cord's tolerance to AXC. Likewise, partial exsanguination is reported to effectively reduce ischemic injury by controlling proximal hypertension. To evaluate the individual and collective efficacy of both techniques, 18 mongrel dogs (25 to 35 kg), divided into three equal groups, underwent a fourth interspace left thoracotomy AXC. Baseline proximal arterial blood pressure (PABP), distal arterial blood pressure (DABP), and CSFP were established and monitored at 5-minute intervals during 120 minutes of AXC, and for 30 minutes thereafter. Group I animals were partially exsanguinated prior to AXC to maintain PABP at a mean of 115 to 120 mmHg. Group II animals had sufficient (16 +/- 5 cc) CSF withdrawn to maintain a DABP-CSFP gradient, i.e., spinal cord perfusion pressure (SCPP) of 20 mmHg. Group III animals were treated with both CSF drainage and partial exsanguination in the same manner as groups I and II, respectively. Perioperative somatosensory evoked potential (SEP) monitoring evaluated cord function. Postoperative neurological outcome was assessed with Tarlov's criteria. SEPs degenerated approximately 22 minutes following AXC for groups II and III. In contrast, group I exhibited rapid (10 +/- 7 min) SEP loss. All five surviving group I animals displayed paralysis 48 hours postoperatively.(ABSTRACT TRUNCATED AT 250 WORDS)

Lipomatous hypertrophy of the interatrial septum.

Lipomatous hypertrophy of the interatrial septum, a finding associated with obesity and advancing age, consists of accumulation of adipose tissue including fetal adipose tissue in the interatrial septum. It is a rare lesion of the heart and can reach notable size. A case is reported in which the diagnosis of lipomatous hypertrophy of the interatrial septum was established intraoperatively; the large bulk of the lipoma was such that it required major reconstruction of the interatrial septum and right and left atrial walls.

Dynamic cardiomyoplasty: left ventricular diastolic compliance at different skeletal muscle tensions.

The possible limitation of left ventricular (LV) relaxation during diastole is a concern for clinicians and researchers utilizing dynamic cardiomyoplasty. This study was designed to evaluate the LV compliance at three different skeletal muscle tensions, in a normal heart and in a failing heart, created by propranolol infusion (11.6 mg/kg). A biventricular latissimus dorsi muscle (LDM) wrap was performed in 10 dogs. The LV pressure (Millar) and two minor axis dimensions (endocardial crystals) were measured. LV pressure-volume loops were constructed, and LV diastolic compliance was calculated. The measurements were obtained before wrap and after wrap at different LDM tensions with 0, 5, and 10 volts stimulation each time. These measurements were repeated after propranolol treatment. The results showed that LV diastolic compliance (dV/dP) was 1.79 before wrap and about 0.7 after wrap, and after propranolol, at various tensions and stimulations. LDM wrap decreased LV compliance significantly. LV compliance was not significantly affected by changing tension or voltage of stimulation in either the failing or the non-failing heart. The reduction in compliance may be an indication that LDM wrap causes a limitation of LV relaxation, which is one of wrap's deleterious effects.

Acute mesenteric ischemia after cardiopulmonary bypass.

Three thousand sixty-six patients underwent cardiopulmonary bypass at the Maimonides Medical Center over a 5-year period from January 1, 1987, to January 1, 1992. Of these patients, 1,890 (62%) were less than 70 years of age, 969 (32%) ranged from 70 to 79 years of age, and 207 (7%) were 80 years of age or older. The overall 30-day mortality rate was 8%. Eleven patients developed acute mesenteric ischemia from 24 hours to 12 days postoperatively. At the time of diagnosis, the majority of patients presented with late classical signs and symptoms of acute mesenteric ischemia including abdominal distension, respiratory distress, hypotension, oliguria, and sepsis. All patients underwent immediate laparotomy. Extensive bowel necrosis was found in all, and resection was possible in eight patients. All patients died as a result of this complication. Using the exact trend test, we found a statistically significant increase in the incidence of deaths due to acute mesenteric ischemia after cardiopulmonary bypass in older compared with younger patients. This fatal complication after cardiopulmonary bypass occurs more often than previously believed and is a relatively common cause of death in the elderly.

The relationship between timing of repair of disruptions and subsequent aneurysm formation in laser-assisted microvascular anastomoses.

In this study we investigated the effects of duration of bleeding after laser-assisted microvascular anastomoses and the amount of laser energy used to control bleeding on aneurysm formation. Eighty femoral arteries were exposed in 40 Sprague-Dawley rats anesthetized with chloral hydrate. The arteries were transected and then anastomosed end-to-end with three nylon stay sutures followed by irradiation of the vessels with energy from a CO2 laser. The laser power was kept at 90 mW, and each of three segments between stay sutures was exposed for 6 seconds to continuous laser energy. If anastomotic disruption (defined as bleeding after completion of the anastomosis) occurred, it was controlled with pressure over the disrupted site for 10, 25, or 40 seconds. Disruptions were required with exposure to additional laser energy for either 6 (group 1) or 12 seconds (group 2). The anastomoses were inspected at 21 days postoperatively to assess patency and aneurysm formation. Twenty-six of 80 vessels (32%) were anastomosed without the occurrence of disruptions: these 26 vessels had a 100 per cent patency rate and did not develop aneurysms. In group 1, the incidence of redisruption following a primary disruption was the same irrespective of duration of bleeding (4/8, 3/6, and 3/6 for 10-, 25-, and 40-seconds bleeding time, respectively P = NS). Similarly, there was no difference in the incidence of aneurysm formation in this group (0/8, 2/6, and 2/6 for 10, 25, and 40", respectively, P = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Intrathecal perfusion of an oxygenated perfluorocarbon prevents paraplegia after aortic occlusion.

A canine model was used to evaluate the effects of continuous intrathecal perfusion of an oxygenated perfluorocarbon emulsion on systemic and cerebral hemodynamics and neurologic outcome after 70 minutes of normothermic aortic occlusion. Twelve mongrel dogs were instrumented to monitor proximal and distal arterial blood pressure, cerebrospinal fluid pressure, spinal cord perfusion pressure, and somatosensory evoked potentials. The intrathecal perfusion apparatus consisted of two perfusing catheters, placed in the intrathecal space through a laminectomy, and a draining catheter percutaneously inserted in the cisterna cerebellomedullaris. The aorta was cross-clamped just distal to the left subclavian artery for 70 minutes. Animals were randomized into two groups: group 1 (n = 6) animals were treated with intrathecal perfusion of saline solution, whereas group 2 (n = 6) animals received oxygenated Fluosol-DA 20%. Data were acquired at baseline, during the cross-clamp period, and after reperfusion. Normothermic Fluosol or saline solution was infused at a rate of 15 mL/min beginning 15 minutes before cross-clamping and continued throughout the ischemic interval. There was no difference in proximal arterial blood pressure (97.2 versus 95.4 mm Hg; p > 0.05) or distal arterial blood pressure (14.6 versus 15.0; p > 0.05) between the two groups throughout the cross-clamp interval. Cerebrospinal fluid pressure rose significantly in both groups with the onset of intrathecal perfusion of either saline solution or Fluosol (7 +/- 1 versus 24 +/- 5 and 8 +/- 1 versus 40 +/- 4 mm Hg, respectively; p < 0.05). The rise in cerebrospinal fluid pressure was sustained throughout the perfusion interval in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Internal mammary artery bypass: thirteen years of experience. Influence of angina and survival in 5125 patients.

Internal mammary artery (IMA) bypass to the anterior descending coronary artery (ADA) was performed in 5125 patients from January 1978 to December 1990. The average age of patients was 68 years; males accounted for 68% (3485 patients) and 82% (4203) were NYHA Class III. Left ventricular function was impaired (ejection fraction < 40%) in 68% (3485 patients). The average number of additional saphenous vein graft (SVG) per patient was 2.2. Operative mortality was 1.8%. Mediastinitis occurred in 51 patients (1.0%). Reoperation for bleeding was necessary in 56 patients (1.1%). Perioperative myocardial infarction was seen in 102 patients (2.0%) and neurological complications occurred in 51 patients (1%). Repeat coronary angiography was performed in 1414 patients (28%) and demonstrated a patency rate of 96% in IMA grafts and 75% in SVG grafts (p < 0.001). Survival at 13 years was 80% from all causes and 90% when non-cardiac deaths were excluded. Recurrence of angina occurred in 768 patients (15%) and reoperation or PTCA was performed in 61 (1.2%). During the same time period, 2345 patients underwent coronary artery bypass utilizing solely SVG. Survival at 13 years was 68% from all causes and 78% when non-cardiac deaths were excluded (p < 0.001). Recurrent angina was present in 727 patients (31%) (< 0.001). This data suggests that long-term probability of cumulative survival and occlusion free survival were significantly greater and the probability of recurrent angina and reoperative CABG and death from cardiac causes were significantly less in the IMA patients and should be the conduit of choice in coronary bypass surgery.

Aortoventriculoplasty in the management of an infected Cabrol graft.

This report describes use of a modified aortoventriculoplasty (Konno procedure) for reoperation on a patient with prosthetic aortic valve conduit endocarditis. The modified Konno procedure was necessary to expose the mid-left ventricular outflow tract to reconstruct an aortic annulus.

A multimodality approach lengthens warm ischemic time during aortic cross-clamping.

To evaluate the effects of exsanguination, cerebrospinal fluid drainage (CSFD), steroids alone and in conjunction with CSFD on spinal cord perfusion pressure (SCPP), and neurological outcome following 70 min of normothermic spinal cord ischemia, we monitored proximal (Px BP) and distal (Ds BP) aortic blood pressure, cerebrospinal fluid pressure, and somatosensory evoked potentials (SEP) in 29 mongrel dogs. In all animals Px BP during aortic cross-clamping was controlled with partial exsanguination (40-50% circulating blood volume). Dogs were randomized into four groups (gp): gp 1 (n = 6) control; gp 2 (n = 8) steroids only (methylprednisolone 30 mg/Kg 10 min before aortic occlusion and 4 hr later); gp 3 (n = 8) CSFD only; gp 4 (n = 7) steroids and CSFD. Partial exsanguination effectively controlled Px BP during aortic cross-clamping in all groups. After the statistically significant decrease from preclamp values, mean Px BP did not differ among groups (78.9, 81.2, 80.5, and 80.3 mm Hg, respectively, P greater than 0.05). Mean Ds BP decreased from systemic values to 12.6, 16.8, 16.7, and 17 mm Hg, respectively, after aortic occlusion (P less than 0.05); these values did not differ from one another. CSFP did not change significantly from its baseline value while the aorta was cross-clamped in gp 1; CSFP was significantly reduced to 6.2 mm Hg in gp 2, steroid-treated animals (P less than 0.05 vs gp 1); a further significant reduction in CSFP was noted in gp 3 and 4 undergoing CSFD (0.07 and 0.67 mm Hg, respectively, P less than 0.05 vs gp 1 and 2).(ABSTRACT TRUNCATED AT 250 WORDS)

Laser welding and irradiation in alcohol preserved homografts.

This experiment examined the effect of laser welding and irradiation on the patency rate of microvascular anastomoses done with alcohol preserved homografts. The carotid arteries from Sprague-Dawley rats were freshly harvested and preserved in 70% ethyl alcohol for at least 3 weeks. The homografts were interposed into the carotid arteries with one of the following techniques: Group I, grafts were anastomosed with three stay sutures and laser welding (carbon dioxide laser, 90 mW); Group II, anastomoses were completed with eight to nine interrupted sutures (10-0 nylon); or Group III, the same technique used in Group II, but followed by laser irradiation (90 mW for 1 min) of the grafts. These results showed that patency at 2 weeks was 73% in Group I, 71% in Group II, and 82% in Group III, respectively. The patency at 12 weeks was 67% in Group I and unchanged in Groups II and III. In conclusion, laser irradiation and laser welding did not increase the patency rate of microvascular anastomoses done with alcohol preserved homografts. Thrombotic occlusion in microvascular homografts usually occurs before the second week postoperatively.

Internal mammary coronary artery anastomosis by CO2 laser: an acute experimental study.

This study was designed to determine the feasibility of anastomosing the internal mammary artery (IMA) and coronary artery with a carbon dioxide laser in a canine model. Twenty-two mongrel dogs were randomly assigned to two groups: group I (n = 11) underwent laser-assisted vascular anastomosis (LAVA) of the left IMA to the left anterior descending (LAD) coronary artery, whereas in group II (n = 11) the anastomosis was done with the conventional technique (handsewn). Laser methodology was used to micro-weld vessels utilizing a power of 200 mW with a spot size of 500 mu, producing an effective power density of 102 W/cm2 and energy fluence of 9,172 joules/cm2 in a continuous mode at a distance of 2 cm. The short-term patency rate, measured at 2 hours after completion of the anastomosis, was 100% in both groups. The time required to perform the LAVA in group I was significantly shorter than group II (6.27 +/- 0.47 vs 11.6 +/- 0.67 min, p less than 0.05). The mean anastomotic bursting pressure in group I was significantly lower compared to group II (348 +/- 8 vs 402 +/- 9 mmHg, p less than 0.05). Histologic evaluation of all vessels showed moderate thermal injury of the adventitia and media in the laser group. Scanning electron microscopy exhibited a smooth anastomotic area in group I, whereas endothelial and perianastomotic changes with multiple needle craters occurred in group II (conventional anastomosis).(ABSTRACT TRUNCATED AT 250 WORDS)

Efficacy of right atrial infusion of PGE1 in sepsis-induced pulmonary hypertension.

In this study we investigated the effects of right atrial infusion of PGE1 (RAIPGE1) in doses from 40 to 500 ng/kg/min on sepsis-induced pulmonary artery hypertension (SIPAH). Thirteen pigs were randomized into a time-course group (n = 6) and a PGE1-treated group (n = 7). Pulmonary hypertension (PAH) was induced with the infusion of Pseudomonas Aeruginosa (PsAr) at a concentration of 2 X 10(8) CFU/20 kg/min in both groups. The infusion of PsAr caused a significant and persistent rise in mean pulmonary artery pressure (MPA), pulmonary vascular resistance (PVRI), right ventricular compliance (RVC), RV dp/dt, and right ventricular stroke work index (RVSWI), 30 min after the onset of infusion (P less than 0.05 vs baseline). Systemic hemodynamics and gas exchange were not affected throughout the 3-hr period of infusion (P = NS); however, left ventricular compliance (LVC) was depressed at a MPA greater than 35 mm Hg. The RAIPGE1 following SIPAH caused a concentration-dependent reduction above 40 ng/kg/min of MPA, PVRI, RVSWI, and RV dp/dt (P less than 0.05, 120 and 500 ng/kg/min vs PAH). RVC returned to baseline values during the infusion of PGE1. Systemic hemodynamics, including oxygen delivery and extraction, were unaffected by the infusion of PGE1, but LVC was improved (P less than 0.05, PGE1 500 vs PAH). The infusion of PGE1 caused a concentration-dependent rise in shunt fraction (Qs/Qt) and alveolararterial oxygen gradients which reached statistical significance during the infusion of 500 ng/kg/min. Our data show that RAIPGE1 is effective in ameliorating RV and pulmonary hemodynamics, but at the largest dose it negatively affects gas exchange.

Influences of laser pulse duration and anastomotic disruption on laser-assisted microvascular anastomoses (LAMA).

The success rate of laser-assisted microvascular anastomosis (LAMA) can be influenced by many factors, including the parameters of the laser technique used. This study examined the effects of laser pulse duration and the occurrence of anastomotic disruption immediately following first repair attempts on the incidence of aneurysm formation and the patency rate in LAMA. Fifty transected rat femoral arteries in 25 rats were anastomosed with three stay sutures and welded with a CO2 laser at a power of 80 mW. In each rat, the laser was applied in the form of 45 pulses of 0.2 sec duration to one femoral artery (group 1) and in the form of 15 pulses of 0.6 sec duration to the contralateral femoral artery (group 2). Comparison of group 1 with group 2 showed that overall rates of aneurysm formation (30% vs. 17%) and patency rates (92% vs. 96%) did not differ significantly (P less than 0.05) at 3 weeks postoperatively. However, disrupted vessels in both groups had a significantly higher incidence of subsequent aneurysm formation than nondisrupted vessels (54% vs. 0% in group 1, P less than 0.05; 43% vs. 6% in group 2, P less than 0.06; groups 1 and 2 pooled, P less than 0.001). These findings indicate that changes in laser pulse duration such as those tested do not affect the aneurysm and patency rates of LAMA. The results demonstrate, however, that disruption after laser welding plays a significant role in subsequent aneurysm formation.

Demographic changes in coronary artery bypass surgery and its effect on mortality and morbidity.

Over the past 4-5 years, possibly with the advent of percutaneous transluminal coronary angioplasty (PTCA), there has been a changing patient population for coronary artery bypass surgery (CABS) with a gradual increase in the operative mortality. In an attempt to analyze the changing demographics in patients undergoing CABS and its effect on operative mortality, we analyzed data from 5536 consecutive patients undergoing isolated CABS. There was 4151 patients less than 70 years of age and 1385 patients greater than 70 years. Reoperative CABS procedures were performed in 385 patients, and CABS for post infarction unstable angina pectoris was performed in 578 patients. During the same time period, 2910 patients underwent PTCA. The mean age of bypass patients was 68.5 years with 38% being 70 years or older. The left ventricular ejection fraction in patients undergoing CABS averaged 38%. The average number of bypasses performed was 3.1. In comparison, patients presenting for PTCA were younger (average age 55), had normal ejection fractions (average 55%) and were predominantly treated for single or double vessel disease. The hospital mortality for elective CABS in patients less than 70 years of age was 1.8%, for reoperative CABS 3.6%, for post infarction unstable angina pectoris 4%, and for patients greater than 70 years 8%, for a combined operative mortality of 4.8%. These data suggest that because of the increasing number of elderly patients (greater than 70 years of age), and the increasing number of reoperative CABS cases and acute myocardial infarction patients with unstable angina pectoris presenting for CABS, the operative mortality will continue to rise.