Integrated microscopy techniques for comprehensive pathology evaluation of an implantable left atrial pressure sensor.

The safety and efficacy of an implantable left atrial pressure (LAP) monitoring system is being evaluated in a clinical trial setting. Because the number of available specimens from the clinical trial for histopathology analysis is limited, it is beneficial to maximize the usage of each available specimen by relying on integrated microscopy techniques. The aim of this study is to demonstrate how a comprehensive pathology analysis of a single specimen may be reliably achieved using integrated microscopy techniques. Integrated microscopy techniques consisting of high-resolution gross digital photography followed by micro-computed tomography (micro-CT) scanning, low-vacuum scanning electron microscopy (LVSEM), and microground histology with special stains were applied to the same specimen. Integrated microscopy techniques were applied to eight human specimens. Micro-CT evaluation was beneficial for pinpointing the location and position of the device within the tissue, and for identifying any areas of interest or structural flaws that required additional examination. Usage of LVSEM was reliable in analyzing surface topography and cell type without destroying the integrity of the specimen. Following LVSEM, the specimen remained suitable for embedding in plastic and sectioning for light microscopy, using the positional data gathered from the micro-CT to intersect areas of interest in the slide. Finally, hematoxylin and eosin (H&E) and methylene blue staining was deployed on the slides with high-resolution results. The integration of multiple techniques on a single specimen maximized the usage of the limited number of available specimens from the clinical trial setting. Additionally, this integrated microscopic evaluation approach was found to have the added benefit of providing greater assurance of the derived conclusions because it was possible to cross-validate the results from multiple tests on the same specimen.

Conventional coronary artery bypass grafting: why women take longer to recover.

BACKGROUND: Recovery following successful coronary artery bypass grafting (CABG) has been dramatically improved with the use of fast-track methods. Although data exist that demonstrate a significant gender difference in survival following CABG, little is known about factors influencing gender-specific recovery. This report describes a series of consecutive patients undergoing isolated CABG to determine gender-associated factors that may impact outcomes and recovery. METHODS: Five hundred and seventeen consecutive patients underwent isolated CABG utilizing cardiopulmonary bypass and were retrospectively reviewed. The outcomes of 351 men in the study were compared to the group of 160 women. A rapid recovery protocol focused on reduced cardiopulmonary bypass time, aggressive preoperative intra-aortic balloon pump use, early extubation, perioperative administration of corticosteroids and thyroid hormone, aggressive diuresis and atrial fibrillation prevention was applied to all patients. RESULTS: The 30-day mortality rate for the women was 4.2% (Parsonnet risk 16.3+/-9.0) compared with 3.4% (Parsonnet risk 9.9+/-7.5) for the men. There were no statistically significant differences in the 30-day mortality rates or postoperative complication rates between the women and men. The women, however, were found to be older (71+/- years versus 65+/- years, p<0.001), and to have a higher incidence of acute myocardial infarction (31% versus 20%, p<0.05), obesity (23% versus 10%, p <0.05), diabetes (31% versus 22%, p<0.05), hypertension (65% versus 48%, p<0.001), and symptomatic vascular disease (20% versus 12%, p<0.05). The women required fewer bypass grafts (2.9 versus 3.5 grafts, p<0.001), and consequently, had shorter cross and cardiopulmonary bypass times. Rapid recovery with discharge before the fifth postoperative day was achieved in 30% of the women, in comparison to 44% of the men (p<0.01). The postoperative hospital length of stay was longer for the women in comparison to the men (7.2+/-7.1 versus 5.8+/-5.2 days, p<0.05). CONCLUSIONS: Women had similar operative mortality and postoperative complication rates to men under a rapid recovery protocol. However, women have a longer recovery interval compared to men, which may be a reflection of their higher preoperative risk profile.

Simplified Parsonnet risk scale identifies limits to early patient discharge.

BACKGROUND: Fast-track recovery after coronary artery bypass surgery has influenced patient care positively. Predicting patients who fall off track and require prolonged (> or =7 days) hospitalization remains uncertain. The Parsonnet risk assessment score is effective in predicting length of stay, but is limited by inaccurate subdivision of risk categories. We simplified the Parsonnet risk scale to better identify patients eligible for fast-track recovery. METHOD: The cases of 604 consecutive patients who underwent isolated coronary artery bypass grafting (CABG) using cardiopulmonary bypass (CPB) were reviewed retrospectively. A rapid recovery protocol emphasizing reduced CPB time, preoperative intra-aortic balloon pump (IABP) criteria, and atrial fibrillation prophylaxis was applied to all patients. The five original divisions of the Parsonnet risk scale were reduced to three risk categories: Low (0-10; Group A), Intermediate (11-20; Group B), High (> 20; Group C). Comparisons of progressive risk categories were analyzed to identify predictive factors associated with fast-track outcomes. RESULTS: The thirty-day operative mortality for the entire group was 3.6%. Three clinical features were identified that distinguished risk progression-female gender, reoperative CABG, and increased age. Additionally, the presence of diabetes (p < 0.05), congestive heart failure (p < 0.01), and peripheral vascular disease (p < 0.001) distinguished Groups A and B, while acute myocardial infarction (p < 0.05) influenced outcomes in Group C. Group A (48%) mean risk score 5.9+/-3.2 was compared to Group B (34%) 14.8+/-2.6, which was further compared to Group C (18%) 26.4+/-2.8. The mean length of stay for Group A (5.3+/-4.1 days) was notably less than Group B (6.1+/-4.7 days; p < 0.05); however, both groups responded favorably to fast-track techniques. Group C did not respond comparably (9.2+/-9.2 vs 6.1+/-4.7 days; p < 0.001) and experienced prolonged recovery. The simplified Parsonnet risk scale did not identify differences in operative mortality and revealed only pneumonia (p < 0.05) and atrial fibrillation (p < 0.01) to be greater in Group C. As risk increased, significantly less revascularization was performed (Group A 3.6+/-1.2 grafts/patient vs Group B 3.3+/-1.2 [p < 0.01]; Group B 3.3+/-1.2 vs Group C 2.5+/-1.0 [p < 0.001]). CONCLUSION: A simplified Parsonnet risk scale (three categories) is an effective tool in identifying factors limiting fast-track recovery. Low- and intermediate-risk patients represent the majority (82%) and respond well to fast-track methods. High-risk patients (18%) are limited by a greater percentage of female patients, reoperative CABG, and the very elderly, resulting in fast-track failure. Strategies to improve recovery in high-risk patients may include evolving off-pump techniques.

Initial experience with beating heart surgery: comparison with fast-track methods.

Cardiopulmonary bypass (CPB) in coronary artery bypass grafting (CABG) may increase postoperative complications in high-risk patients. The goal of this study is to retrospectively review a series of consecutive patients undergoing conventional CABG using a fast-track recovery method and to compare this series with the initial series of patients undergoing beating heart surgery using either the single-vessel minimally invasive approach or the off-pump multivessel bypass technique with a median sternotomy. One hundred fifty-eight consecutive patients underwent CABG. One hundred four patients underwent conventional CABG using CPB with a short-pump fast-track recovery method (Group A). Twenty-nine patients underwent a single-vessel bypass via a left anterior thoracotomy off pump [Group B, minimally invasive direct coronary artery bypass (MIDCAB)]. Twenty-five patients underwent multivessel CABG with a median sternotomy off pump (Group C). Short-pump fast-track (Group A) patients exhibited minimal complications and expedient recovery and received extensive revascularization. Off-pump multivessel patients (Group C) received fewer bypass grafts, had more preoperative comorbidity, and recovered as quickly as lower-risk fast-track short-pump patients (Group A). Single-vessel off-pump patients (Group B, MIDCAB) were younger elective patients and demonstrated no recovery advantage. The overall mortality was 1.8 per cent. The conversion rates from beating heart surgery to CPB for groups B and C were 10.3 and 16 per cent, respectively. The postoperative hospital length of stay for groups A, B, and C were 4.8+/-2.4, 3.9+/-1.8, and 5.2+/-2.3 days, respectively. Eliminating CPB is not as important as reducing exposure for minimizing operative risk. Beating heart surgery is an adjunct to conventional CABG with CPB. The off-pump multivessel bypass technique is best suited for high-risk patients requiring three grafts or fewer, whereas MIDCAB is best suited for single-vessel bypass that cannot be managed using interventional percutaneous techniques; however, the recovery advantage with MIDCAB is not apparent. Patients requiring more than three bypass grafts should undergo conventional CABG with CPB.

Aggressive preoperative use of intraaortic balloon pump in elderly patients undergoing coronary artery bypass grafting.

BACKGROUND: The use of the intraaortic balloon pump (IABP) in patients undergoing coronary artery bypass grafting has been traditionally associated with a high complication rate and adverse outcomes. However, recent reports show that many of these catastrophic outcomes can be avoided by preoperatively placing the IABP in high-risk patients. To further validate these reports, we defined a set of liberal criteria for preoperative IABP insertion and applied them to a series of elderly patients (70 years or older) undergoing isolated coronary artery bypass grafting. METHODS: Two hundred six consecutive patients who underwent isolated coronary artery bypass grafting with cardiopulmonary bypass were retrospectively reviewed. A rapid recovery protocol emphasizing reduced cardiopulmonary bypass time, an anesthetic protocol for early extubation, perioperative administration of corticosteroids and thyroid hormone, and aggressive diuresis was applied to all patients. Patients who required an urgent operation because of failed percutaneous transluminal coronary angioplasty, a critical left main stenosis (70% or greater), pronounced left ventricular dysfunction (left ventricular ejection fraction 40% or less), or unstable angina refractory to medical therapy or who required an emergency reoperation received preoperative IABP support. RESULTS: The 30-day mortality rate for the entire group was 4.4%. There were 97 patients (47%) who received a preoperative IABP (group II) in comparison with 109 patients (53%) who did not fulfill the preoperative insertion criteria (group I). Patients in group II had a lower left ventricular ejection fraction (mean, 46% versus 59%, p<0.001) and a higher incidence of congestive heart failure (35% versus 17%, p<0.01) and acute myocardial infarction (37% versus 17%, p<0.01) than patients in group I. The average postoperative hospital length of stay for patients in group II was slightly longer than for those in group I (9.0+/-10.5 versus 6.0+/-3.7 days, p<0.01). However, there were no statistically significant differences in complication or mortality rates between the two groups. Only 2 patients (2.2%) had complications related to IABP insertion. Lower extremity ischemia occurred in both patients, and both were treated successfully with thromboembolectomy. CONCLUSIONS: Liberal preoperative insertion of the IABP can be performed safely in high-risk elderly patients undergoing coronary artery bypass grafting, with results comparable to those in lower risk patients.

Reduced postoperative atrial fibrillation using multidrug prophylaxis.

BACKGROUND: Atrial fibrillation (AFIB) is the most common complication following coronary artery bypass grafting (CABG). Despite three decades of recognition, efforts to reduce the high incidence reported (15%-30%) have been largely unsuccessful. Reasons for postoperative AFIB are likely multifactorial. As a result, we defined a multidrug prophylaxis based on agents known to be individually effective. This method was applied prospectively to a series of consecutive CABG patients with the goal of reducing the incidence of new-onset postoperative AFIB. METHODS: Isolated CABG with cardiopulmonary bypass was performed on 517 consecutive patients. A rapid recovery protocol emphasizing AFIB multidrug prophylaxis was applied to all patients. All patients received 10 microg of triiodothyronine intraoperatively when the clamp on the aorta was released. Immediately following CABG, parenteral magnesium was administered to assure a serum magnesium > 2.2 mEq/dL. Thyroxine 200 microg was administered parenterally to all patients on postoperative days 1 and 2. Metoprolol (25 mg to 100 mg/day) was begun on all patients after extubation provided: heart rate > 85 beats/min and systolic blood pressure > 130 mmHg. Parenteral procainamide (12 mg/kg) loading dose, followed by a maintenance dose (2 mg/min), was used for patients who developed premature atrial contractions (> 1/min), nonsustained supraventricular tachycardia, or any episodes of atrial fibrillation. All patients also received postoperative digitalization, steroids, and aggressive diuresis. RESULTS: The 30-day operative mortality was 3.7%. The overall incidence of new-onset postoperative AFIB was 10.3% (53 patients). There was no major difference in operative mortality (7.5% vs 3.2%, p = 0.23), Parsonnet risk score, or intraoperative variables between AFIB patients and the non-AFIB patients. Patients presenting with a preoperative acute myocardial infarction (p < 0.05), left main stenosis > or = 70% (p < 0.01), and advanced age > or = 70 years (p < 0.05) were at increased risk of developing AFIB. The length of stay for patients with AFIB was 9.9 +/- 9.6 days versus 5.9 +/- 5.2 days (p < 0.001). CONCLUSION: Application of a multidrug prophylaxis can reduce postoperative AFIB to a low incidence. Identification of associated clinical features can help predict patients at risk for postoperative AFIB. Additional strategies to target postoperative AFIB may include treatment at the earliest recognition of atrial rhythm instability.

Coronary artery bypass grafting "on pump": role of three-day discharge.

BACKGROUND: A new emphasis has been directed toward "off-pump" coronary artery bypass grafting to avoid the morbidity of cardiopulmonary bypass and further reduce the postoperative hospital length of stay. With the intent of achieving a hospital discharge for "on-pump" coronary artery bypass grafting procedures comparable with the same procedures "off pump," we applied a rapid-recovery protocol with particular attention paid to patients eligible for discharge on the third postoperative day. METHODS: The cases of 104 consecutive patients who underwent isolated coronary artery bypass grafting using cardiopulmonary bypass were retrospectively reviewed. A rapid-recovery protocol emphasizing reduced cardiopulmonary bypass time, an anesthesia protocol for early extubation, perioperative administration of corticosteroids and thyroid hormone, and aggressive diuresis was applied to all patients. The goal during the first 24 hours postoperatively was to achieve early extubation as well as a mild state of negative fluid balance and to ensure absence of postoperative bleeding and a safe transfer from the intensive care unit to a monitored floor. On the second postoperative day, chest drains were discontinued, and aggressive ambulation therapy was instituted. If at 72 hours postoperatively the patient was walking without assistance, had return of normal bowel function, and had no atrial fibrillation, a 3-day discharge home was planned. RESULTS: The 30-day mortality rate for the entire group was 1.9%. The average postoperative hospital length of stay for the entire series was 4.8 +/- 2.4 days. Of the 102 survivors, 30 patients (29%) were discharged within 3 days postoperatively (group 1), and 72 patients (71%) were discharged after the third postoperative day (group 2). Patients in group 1 were younger and had fewer comorbid conditions. Compared with group 2, group 1 had fewer patients with diabetes (7% versus 28%; p < 0.05), congestive heart failure (7% versus 18%), symptomatic vascular disease (0% versus 11%), chronic obstructive pulmonary disease (0% versus 10%), ambulatory difficulties (0% versus 10%), and the requirement of an intraaortic balloon pump preoperatively (13% versus 35%). Group 1 patients also had almost no complications and a lower readmission rate (3.3% versus 6.9%). CONCLUSIONS: With the application of a rapid-recovery protocol to patients undergoing "on-pump" coronary artery bypass grafting, discharge home within 3 days postoperatively is attainable and safe for patients who have minimal comorbid conditions.

Rapid recovery after coronary artery bypass grafting: is the elderly patient eligible?

BACKGROUND: Rapid recovery protocols after coronary artery bypass grafting have been applied successfully to young patients with normal ventricular function. However, the success of such protocols when applied to the elderly population has not been thoroughly validated, and at some centers there is still reluctance in allowing elderly patients to be discharged early from the hospital. METHODS: One hundred fifty-two consecutive younger patients (< 70 years) were compared retrospectively with 167 consecutive elderly patients (> or = 70 years) who underwent isolated coronary artery bypass grafting using cardiopulmonary bypass. A rapid recovery protocol emphasizing an anesthetic protocol for early extubation, reduced cardiopulmonary bypass time, and perioperative administration of corticosteroids and thyroid hormone was applied to all patients. The protocol also emphasized early identification and management of postoperative atrial fibrillation, a proactive negative fluid balance, rapid return of bowel function, mobilization of the patient, and aggressive use of the intraaortic balloon pump preoperatively. RESULTS: The 30-day mortality rate for the younger group of patients was 3.3% (Parsonnet risk 7.2 +/- 6.2), compared with 4.2% (Parsonnet risk, 17.7 +/- 6.8) for the elderly group of patients. There were no statistically significant differences in the 30-day mortality rates or postoperative complications between the elderly and younger patient groups. Rapid recovery with discharge before the fifth postoperative day was achieved in 19% of the elderly, in comparison with 48% of the younger patients (p < 0.001). The younger patients were discharged earlier after operation than the older patients (5.7 +/- 5.2 versus 8.0 +/- 8.5 days; p < 0.01). CONCLUSIONS: Application of the rapid recovery protocol helped expedite recovery for all patients regardless of age, acuity of illness, or associated conditions. Although younger patients had a significantly shorter postoperative length of hospital stay, older patients performed well and are suitable candidates for rapid recovery protocols.

Rapid recovery of octogenarians following coronary artery bypass grafting.

BACKGROUND: Rapid recovery protocols for coronary artery bypass grafting (CABG) have resulted in major decreases in postoperative hospital length of stay (LOS) when applied to younger patients undergoing elective procedures. However, the effectiveness of rapid recovery protocols when applied to octogenarians has not been thoroughly studied. METHODS: Thirty-seven consecutive octogenarians underwent isolated CABG utilizing cardiopulmonary bypass (CPB). A protocol emphasizing preoperative placement of the intra-aortic balloon pump, reduced CPB time, early extubation, perioperative steroids, thyroid hormone, and aggressive postoperative diuresis was used. RESULTS: The 30-day operative mortality for the entire series was 5.4%. Twenty-five patients (71%, group I) were discharged in < 10 days postoperatively (average LOS of 6.3 +/- 1.6 days), while ten patients (29%, group II) were discharged at 10 or more days postoperatively (average LOS of 20.3 +/- 8.0, p < 0.001). Patients in group II were found to have a higher incidence of obesity (50% vs 4%, p < 0.01), symptomatic peripheral vascular disease (60% vs 8%, p < 0.01), and preoperative ambulatory difficulties (50% vs 0%, p < 0.01). The incidence of complications was 31% for the entire series, with no differences between the groups. CONCLUSION: Octogenarians performed well under a rapid recovery protocol, with 71% being discharged in < 10 days postoperatively, while patients with obesity, symptomatic peripheral vascular disease, and ambulatory difficulties rehabilitated more slowly.

In vitro atherosclerotic plaque and calcium quantitation by intravascular ultrasound and electron-beam computed tomography.

The purpose of this investigation was to compare the accuracy of intravascular ultrasound (IVUS) and electron-beam computed tomography (EBCT) in quantitating human atherosclerotic plaque and calcium. In experiment 1, 12 human atherosclerotic arterial segments were obtained at autopsy and imaged by using IVUS and EBCT. The plaque from each arterial segment was dissected and a volume measurement of the dissected plaque was obtained by water displacement. The plaque from each arterial segment was ashed at 700 degrees F, and the weight of the remaining ashes was used as an estimate of the calcium mass. In experiment II, 11 calcified arterial segments were obtained at autopsy and imaged by using IVUS at one site along the artery. A corresponding histologic cross section stained with Masson's trichrome was prepared. In experiment I, the mean plaque volume measured by water displacement was 165.3 +/- 118.4 microliters. The mean plaque volume calculated by IVUS was 166.1 +/- 114.4 microliters and correlated closely with that by water displacement (r = 0.98, p < 0.0001). The mean calcium mass measured by ashing was 19.4 +/- 15.8 mg. The mean calculated calcium mass by EBCT was 19.9 mg and correlated closely with that by ashing (r=0.98, p<0.001). The mean calculated calcium volume by IVUS was 18.6 +/- 11.2 microliters and correlated linearly with the calcium mass by ashing (r = 0.87, p < 0.0003). In experiment II, the mean cross-sectional area of the calcified matrix was 1.71 +/- 0.66 mm2 by histologic examination compared with 1.44 +/- 0.66 mm2 by IVUS. There was a good correlation between the calcified cross-sectional area by histologic examination and IVUS (r = 0.76, p < 0.007); however, IVUS may underestimate the amount of calcium present depending on the intralesional calcium morphologic characteristics. In conclusion, IVUS accurately quantitates atherosclerotic plaque volume as well as the cross-sectional area and volume of intralesional calcium, especially if the calcium is localized at the base of the plaque. IVUS underestimates the amount of calcium present because of signal drop-off when the calcium is too thick for the ultrasound to completely penetrate. In comparison, EBCT accurately quantitates calcium mass regardless of the intralesional calcium morphologic characteristics; however, EBCT does not accurately quantitate plaque volume and will miss noncalcified atherosclerotic lesions.

Intravascular ultrasound appearance of normal and mildly diseased coronary arteries: correlation with histologic specimens.

Intravascular ultrasound imaging was performed in vitro on six histologically normal and 104 minimally diseased arteries in patients aged 13 to 83 years. This study tested the hypothesis that normal coronary arteries produce a three-layer image that corresponds to the histologic layers of intima, media, and adventitia. The results showed a very good correlation between area of the echolucent ultrasound layer with the media and the inner echogenic layer with intimal area. In addition, a three-layer appearance was consistently seen when the internal elastic membrane was present with or without intimal hyperplasia. If the internal elastic membrane was absent, a three-layer appearance was still seen if the collagen content of the media was low. However, a two-layer appearance was observed when there was absence of the internal elastic membrane as well as a high collagen content of the media.

Intracoronary ultrasound imaging before and after directional coronary atherectomy: in vitro and clinical observations.

The rate of restenosis after directional coronary atherectomy (DCA) is higher than expected. To elucidate why, the current study used intravascular ultrasound (IVUS) imaging to investigate the mechanism of DCA. An in vitro validation study was performed to determine the accuracy of the measurement of plaque removal by IVUS. DCA was performed in eight human atherosclerotic artery segments. The volume of removed plaque was measured by water displacement and was compared with the volume calculated from IVUS images. A clinical study of DCA was performed in 32 lesions. IVUS was performed in 28 lesions after successful DCA. Measurements of lumen dimensions from digital angiograms before and after DCA were compared with observations of lumen and plaque size from the cross-sectional IVUS images. In the in vitro study, the mean plaque volume removed by DCA was 19.9 +/- 8.5 microliters. The calculated estimate of removed plaque volume by IVUS was 18.6 +/- 7.9 microliters and correlated closely with the volume by water displacement (r = 0.92). The calculated volume of plaque removed from histologic sections was 14.3 +/- 6.0 microliters and was linearly correlated with plaque volume by water displacement (r = 0.81). In the clinical study, the angiographic mean minimum lumen diameter increased from 1.0 +/- 0.4 to 2.7 +/- 0.5 mm and the percentage stenosis decreased from 70% to 19% (p < 0.0001). The IVUS images before and after DCA showed that the lumen DCA improved from 2.9 +/- 1.5 to 7.0 +/- 1.5 mm2 (p < 0.0001). In addition the vessel cross-sectional area (CSA) increased from 17.1 +/- 5.9 to 18.7 +/- 5.5 mm2. The atheroma CSA was reduced from 14.2 +/- 5.0 to 11.7 +/- 4.8 mm2. This combined effect of reduction in atheroma CSA and stretching of the outer vessel diameter resulted in an improvement in percentage plaque area stenosis from 83% +/- 7% to 61% +/- 9%. It is concluded that despite a successful angiographic appearance, DCA removed an average of 2.5 mm2 from the atheroma, which corresponds to only 18% of the atheroma CSA. The total lumen CSA increased 4.1 mm2; 61% of the new lumen was created by cutting and removal of plaque, whereas 39% of the new lumen was made by stretching the external wall of the artery. Despite an excellent angiographic result, IVUS imaging reveals that after DCA a significant amount of residual atheroma remains. As in balloon dilatation, a stretching effect is a significant component of DCA.

Concepts in the application of pneumatic ventricular assist devices for ischemic myocardial injury.

The clinical results of "bridge-to-recovery" from ischemic myocardial injury using pneumatic ventricular assist devices (VADs) have been disappointing, because no significant improvement in the hospital discharge rate (25%) has been observed during the past 10 years. Interestingly, similar results have been reported using the less sophisticated and more widely available centrifugal pumps. It is well recognized that appropriate patient selection and early device implantation are important determinants of patient survival; however, it is less clear why there is a lack of difference in the results between pneumatic VADs and the centrifugal pumps. The reasons for the lack of difference in the results between pneumatic VADs and centrifugal pumps are multifactorial, and to some extent may be due to a conservative approach in the application of the more capable pneumatic VADs. In an effort to provide a more effective approach to the clinical application of pneumatic VADs for bridge-to-recovery, two pneumatic devices (the Jarvik 7-70 total artificial heart and the Symbion acute VAD) were functionally characterized using an in vitro mock circulatory system. The performance under pneumatic VAD asynchronous pumping compared to electrocardiogram synchronous counterpulsation was also evaluated. Based upon the results obtained, a two phase approach was developed. In the initial phase (i.e., the first 12-48 hrs), device output is maximized through asynchronous pumping to rapidly reverse the effects of cardiogenic shock. During the second phase (i.e., after hemodynamic stabilization and early evidence of end-organ recovery), electrocardiogram synchronous counterpulsation is used to focus more specifically on recovery of the heart.(ABSTRACT TRUNCATED AT 250 WORDS)

An explanation for discrepancy between angiographic and intravascular ultrasound measurements after percutaneous transluminal coronary angioplasty.

OBJECTIVES: This study attempted to determine why there is a discrepancy between angiographic and intravascular ultrasound measurements after coronary balloon angioplasty. BACKGROUND: Previous studies have shown a poor correlation between angiographic and intravascular ultrasound measurements after percutaneous coronary balloon angioplasty. METHODS: After successful balloon angioplasty, 91 lesions in 84 patients were studied by intravascular ultrasound. Plaque morphology on intravascular ultrasound was classified as demonstrating a superficial injury if there was either no fracture or only a small tear that did not extend to the media versus a deep injury defined as the presence of a plaque fracture that reached the media. Measurements of minimal lumen diameter were compared between angiography and intravascular ultrasound. RESULTS: On ultrasound imaging, a superficial injury pattern was observed in 44 lesions, whereas a deep injury was seen in 47 lesions. There were no statistical differences at baseline in patient or lesion characteristics. In the superficial injury group there was a significant correlation between angiography and intravascular ultrasound for minimal lumen diameter (r = 0.67) and lumen cross-sectional area (r = 0.69). In the deep injury group there was a poor correlation for minimal lumen diameter (r = 0.05) and lumen cross-sectional area (r = 0.28). After balloon angioplasty, the angiographic appearance showed a normal contour in 34%, the presence of dissection in 38% or a hazy appearance in 23%. On ultrasound imaging after angioplasty, the superficial injury group comprised 65% of lesions with a normal angiographic appearance and 67% of lesions with a hazy appearance, whereas 77% of lesions with an angiographic diagnosis of dissection were in the deep injury group by ultrasound (p = 0.0005). CONCLUSIONS: These observations suggest that the discrepancies between angiographic and ultrasound measurements are due to differences in plaque morphology created by balloon dilation. Superficial injuries demonstrate similar results by angiography or ultrasound, whereas a deep injury to the plaque produces a difference in measurements between angiography and ultrasound. When angiography reveals a dissection, there is a high probability that intravascular ultrasound will demonstrate a plaque fracture extending to the media.