Biomedical subjects

R J Shemin

Publications and source records attributed to R J Shemin.

120 records · Page 7Linked to original sources

PubMed1979

Congenital cardiac abnormalities in monozygotic twins. Report and review of the literature.

A pair of monozygotic twin girls is reported with concordance for 3 congenital cardiac abnormalities: (1) secundum atrial septal defect, (2) aneurysm of the membraneous ventricular septum, and (3) electrocardiographic frontal plane left axis deviation. A review of the published materials shows a 9.5 per cent incidence of concordance for congenital heart disease among monozygotic twins. In those in whom a precise cardiological diagnosis was made, 15/16 pairs (95%) were concordant for a specific defect, 2 had an additional defect, and only 1 pair had completely dissimilar defects. Concordance for congenital heart disease in monozygotic twins is uncommon, but when it occurs the defects will most often be identical.

Child↗

PubMed1979

Evaluation of right atrial-pulmonary artery conduits for tricuspid atresia. Experimental study.

Blood flow through right atrial-pulmonary artery (RA-PA) conduits was investigated. Experiments were designed to evaluate the pumping function of the right atrium, effects of the atrial versus ventricular pacing site, the necessity of a valve within the conduit, and the effect of positive-pressure ventilation on conduit flow. Twenty foxhounds were subjected to silicone patch closure of 90 percent of the tricuspid valve orifices to create stenosis. Ten dogs successfully underwent RA-PA shunting with a conduit with paralled limbs, one containing a prosthetic valve. The proximal main pulmonary artery was ligated to ensure total diversion of blood via the conduit. Valved and nonvalved conduit flow was significantly correlated with right atrial pressure (RAP): r = 0.95, p less than 0.05; r = 0.98, p less than 0.01, respectively. There was no significant effect of increasing heart rate (p = 0.19), atrial versus ventricular rhythm (p = 0.28), or the presence of a valve (p = 0.63). Increasing tidal volume resulted in increasing tidal conduit flow (expiration-inspiration) (r = 1.0, p less than 0.01), but mean flow was unaffected. Therefore, RAP is the most important factor influencing conduit flow. The absence of a valve, ventricular rhythm, and tachycardia did not significantly alter flow in this acute experimental model.

Animals↗

PubMed1978

Limits of myocardial protection with potassium cardioplegia.

Preservation of left ventricular function with various potassium-based cardioplegic solutions has been considered to be effective for at least 60 minutes during occlusion of the ascending aorta. The purpose of this study was to define the limits of protection offered by potassium alone. A single bolus of 150 ml of potassium (24 mEq per liter) in normal saline solution at 30 degrees C was injected in the aortic roots of foxhounds at the initiation of periods of 45 minutes, 60 minutes, and 75 minutes of aortic occlusion at a core temperature of 30 degrees C. Data derived from postischemic recovery phase ventricular function curves and force-velocity relations demonstrated excellent protection during 45 minutes of ischemia, inconsistent protection at 60 minutes, and poor protection at 75 minutes.

Animals↗

PubMed1978

Continuous epicardial echocardiographic assessment of postoperative left ventricular function.

An ultrasound transducer which is sutured to the heart at operation and removal percutaneously has been developed and tested in 20 animals. The potential of this device to monitor cardiac function was measured by simultaneously recording 67 left ventricular angiograms and echograms over a wide range of hemodynamic function. In addition, the reproducibility of the data obtained from the transducer and the safety of application and withdrawal were examined. We found highly significant (p less than 0.005) linear correlation between echocardiographic and angiographic measurements of left ventricular end-diastolic volume, end-systolic volume, and ejection fraction. This transducer may provide the means to assess left ventricular size and ejection fraction continuously after cardiac operations in man.

Animals↗

PubMedDate not supplied

Effective use of heparin-bonded circuits and lower anticoagulation for coronary artery bypass grafting in Jehovah's Witnesses.

Despite many advances in blood conservation techniques, a significant proportion of patients undergoing primary coronary revascularization still require homologous transfusions. Based on a large clinical experience with high-risk patients during coronary artery bypass, a comprehensive strategy to diminish perioperative blood loss was developed by integrating many individual components. An integral component in this strategy is the use of lower heparinization (activated clotting time [ACT] > 280 sec) in conjunction with "tip-to-tip" heparin-bonded cardiopulmonary bypass (CPB) circuits (HBC). This technique was prospectively applied to a group of Jehovah's Witnesses (JW) patients who refuse blood transfusion on religious grounds (n = 9). Outcome was compared to a matched group of patients treated with full heparinization (ACT > 480 sec) used with conventional, nonheparin-bonded CPB circuits (NHBC) performed within the same academic year (n = 455). There were no complications in JW patients who had a significantly lower mediastinal and pleural tube output in the first 24 hours (323 67 mL vs 984 616 mL, p < 0.01). In comparison to JW patients who received no transfusions, 68.1% of patients treated with NHBC were transfused (p 0.0001). In summary, HBC in conjunction with lower anticoagulation was effectively and safely applied to JW patients undergoing coronary artery bypass grafting. This technique should be considered for broader clinical use.

Aged↗

PubMedDate not supplied

Enhanced blood conservation in primary coronary artery bypass surgery using heparin-bonded circuits with lower anticoagulation.

BACKGROUND: Despite many advances in blood conservation techniques, a significant proportion of patients undergoing primary coronary revascularization still require homologous transfusions. A comprehensive strategy to diminish perioperative blood loss was developed by integrating many individual components to create an improved blood conservation environment and was prospectively applied to 557 patients undergoing primary coronary artery bypass grafting (CABG) procedures performed in our medical center over a 14-month period. METHODS: The first 455 patients were treated with conventional, nonheparinbonded circuits (NHBCs) and full anticoagulation (activated clotting time [ACT] > 480 sec). We wanted to test the hypothesis of whether "tip-to-tip" heparin-bonded circuits (HBCs) used in conjunction with lower anticoagulation (ACT > 280 sec) when added to our current blood conservation environment can further enhance clinical outcomes. We prospectively applied this technique to a consecutive group of patients (n = 102). RESULTS: Compared to patients treated with NHBCs, patients treated with HBCs had a significantly lower mediastinal and pleural chest tube output in the first 24 hours (683 +/- 561 mL vs 984 +/- 616 mL, p < 0.00001) were less likely to be transfused (52% vs 68.1%, p < 0.01) and had a lower exposure to different blood donor units (4.1 +/- 8.4 vs 9.3 +/- 10.3, p < 0.000003). There were no complications directly related to HBCs used in conjunction with lower anticoagulation. Morbidity and mortality rates were similar in both treatment groups. CONCLUSION: In summary, HBCs in conjunction with lower anticoagulation were safely applied in patients undergoing primary CABG with marked improvement in blood conservation, and should be considered for broader clinical use.

Aged↗

PubMedDate not supplied

Enhanced blood conservation and improved clinical outcome after valve surgery using heparin-bonded cardiopulmonary bypass circuits.

BACKGROUND: Recently, heparin-bonded (HBC) cardiopulmonary bypass circuits (CPB) were formed to be associated with improved outcome after coronary artery bypass grafting. There are very few reports on the efficacy and safety of these circuits in valve surgery. METHODS: A retrospective cohort study of all patient populations undergoing first time valve surgery from 1992 to 1995 in a tertiary teaching hospital. Outcomes of 120 patients undergoing valve surgery using HBC and lower anticoagulation HBC were compared to 232 patients treated with conventional circuits and full heparinization (nonheparin-bonded-circuit [NHBC]). RESULTS: Postoperative 24-hour chest tube drainage (558 +/- 466 mL vs 1054 +/- 911 mL, p < 0.00001), and reoperation for bleeding (2.5% vs 8.2%, p = 0.04) were lower in the HBC group. HBC patients required significantly less transfusions (total donor exposure of 6.9 +/- 13.0 units vs 18.6 +/- 26.2 units, p < 0.00001). Multiple linear regression analysis identified CPB time as a predictor of increased homologous blood transfusions, and the use of HBC, a large body surface area, and elective procedure as predictors of decreased transfusions. Perioperative mortality was similar (HBC 2.5%, NHBC 4.7%, p = 0.24). Overall complications were lower in the HBC group (42% vs 56.2%, p = 0.02). Perioperative myocardial infarction (0.8% vs 1.3%, p = 0.58) and cerebrovascular accident (3.3% vs 3.9%, p = 0.53) were similar. Two (1.7%) HBC patients had valve re-replacement compared to none in the NHBC (p = 0.22). Multiple logistic regression model revealed that age and CPB time were associated with increased complications, and the use of HBC with reduced complications. CONCLUSION: Use of HBCs with lower anticoagulation in valve surgery resulted in a significant reduction of transfusion requirements and improved clinical outcome. Because of a potential for early mechanical valve thrombosis, until further data is available, conventional levels of systemic anticoagulation should be achieved when using HBC in valve surgery.

Aged↗

PubMedDate not supplied

Endarterectomy of the ascending aorta: an alternative method in patients with extensively calcified (porcelain) aorta requiring aortic valve replacement.

A variety of surgical techniques have been described to manage the extensively calcified (porcelain) aortic root in patients requiring aortic valve replacement. We report two cases in which endarterectomy of the proximal ascending aorta was successfully performed. Endarterectomy of the left main coronary artery ostium was also performed in the one patient, and aortic root enlargement with patch aortoplasty in another. The technical aspects of the procedure and alternative approaches are discussed.

Aged↗

PubMedDate not supplied

Clinical outcomes in patients undergoing coronary artery bypass grafting with preferred use of the radial artery.

BACKGROUND: The use of the radial artery (RA) for coronary artery bypass grafting (CABG) is still not widely accepted. The purpose of this study was to evaluate the impact of preferred RA utilization on clinical outcomes. METHODS: Data on 138 consecutive patients undergoing CABG using the RA (in addition to the internal mammary artery) were prospectively collected and compared to 228 patients undergoing CABG without the RA. RESULTS: The mean age was 56 +/- 10 years (range 29 to 79 years). Preoperatively 91% (126/138) were in CCS angina Class III/IV, 45% (66/138) were nonelective, and 14% (20/138) were reoperations. An average of 3.5 +/- 0.9 grafts per patient were performed, of which 2.5 +/- 0.5 (71%) were arterial. The RA was used for single distal vessel in 103 patients, for sequential grafting in 35, and overall for 1.3 distal targets per patient. There were no perioperative deaths, reoperation for bleeding, MI, or CVA. Six patients (4%) had minor RA harvest-related complications. The length of hospital stay was 5.6 +/- 3.1 days. Hospital outcomes were similar to a cohort of patients undergoing CABG without RA. Mean follow-up for 99% (137/138) of patients was 7.1 +/- 4.3 months (range 1 to 18 months). Long-term major complications included one sudden death (0.7%) and three MIs (2.2%). At the time of follow-up, 95% (1311137) were in CCS angina Class I/II. Routine thallium stress test performed in 93 patients showed normal perfusion in 98%. There were no long-term major vascular or neurological deficits related to RA harvest. CONCLUSIONS: The use of RA in patients undergoing CABG is safe and effective. These excellent early clinical outcomes justify liberal use of the RA, although long-term follow-up is required to establish its ultimate role as a preferred conduit.

Adult↗

PubMedDate not supplied

Heparin-bonded circuits improve clinical outcomes in emergency coronary artery bypass grafting.

Compared to patients undergoing elective or urgent coronary artery bypass grafting (CABG), those undergoing emergency CABG (EM-CABG) have a higher morbidity and mortality. The use of heparin-bonded circuits (HBC) has been shown to improve clinical outcomes in nonemergent CABG patients. It is not known, however, whether the improved hemostasis and attenuation of the inflammatory response to cardiopulmonary bypass, conferred by HBC, can overcome the high incidence of comorbid risk factors in (EM-CABG) patients and improve their outcomes. A retrospective analysis of 206 consecutive patients undergoing EM-CABG over 4 years (1993-1997) at one institution was performed. Eighty-one patients were treated with conventional non-heparin-bonded circuits (NHBC) with full anticoagulation protocol (FAP, activated clotting time [ACT] > 480 sec); 125 patients were treated with HBC and a lower anticoagulation protocol (LAP, ACT > 280 seconds). Outcomes and results were collected prospectively and are presented as mean +/- SD. Preoperative risk profiles were similar in both treatment groups. Postoperatively, compared with the NHBC group, patients treated with HBC/LAP required fewer homologous donor units (4.1 +/- 10.7 vs 8.2 +/- 13.6 units, p = 0.005), were less likely to require inotropic support (18.6% vs 38.3%, p = 0.005), and had a lower incidence of perioperative myocardial infarction (MI, 3.2% vs 12.3%, p = 0.04) and pulmonary complications (4.0% vs 12.3%, p = 0.04). The use of HBC/LAP resulted in a decreased incidence of postoperative complications (12.8% vs 28.4%, p = 0.01, odds ratio 0.37 with 95% confidence interval [CI] 0.18-0.76). This resulted in a shorter duration of ventilatory support (30.5 +/- 54.0 vs 72.8 +/- 16.7 hours, p = 0.009), ICU stay (38.2 +/- 36.5 vs 91.5 +/- 68.7 hours, p = 0.009), hospital stay (8.0 +/- 7.1 vs 11.0 +/- 8.9 days, p = 0.008), and therefore cost. In conclusion, the use of HBC/LAP in EM-CABG resulted in a reduction of homologous transfusion and postoperative complications associated with decreased hospital stays and cost.

Aged↗

PubMedDate not supplied

Heparin-bonded cardiopulmonary bypass circuits reduce bleeding and transfusion requirements in proximal aortic surgery.

BACKGROUND: Methods to improve hemostasis in aortic surgery continue to evolve. Use of heparin-bonded cardiopulmonary bypass circuits (HBC) has been shown previously to effectively reduce bleeding and improve outcomes in coronary and valve operations. OBJECTIVE: To evaluate the impact of HBC on bleeding and transfusion requirements in proximal aortic surgery. METHODS: Data on 140 consecutive patients undergoing 144 operations of the proximal aorta were collected. Between July 1987 and July 1994, conventional cardiopulmonary bypass circuits (CONV) were used (n = 53). In July 1994, we switched to "tip-to-tip" HBC (n = 91). This study compared clinical outcomes and transfusion requirements between these two groups. RESULTS: Indications for surgery, baseline characteristics, and operative profile of the study groups were similar. Overall operative mortality and reoperation for bleeding were 9% and 13%, respectively. Compared with CONV, use of HBC was associated with decreased mortality (3% vs 18%, p = 0.004), reoperation for bleeding (7% vs 24%, p = 0.005), and hospital length of hospital stay (10 +/- 11 vs 20 +/- 30 days, p = 0.002). Although the incidence of allogeneic blood transfusion was similar (HBC 75% vs CONV 87%, p = 0.12), the magnitude of blood products utilization was much lower in the HBC group (total blood products per patient: 24 +/- 29 vs 49 +/- 47 donor units, p = 0.0002). In the multivariate analyses, use of HBC was identified as an independent predictor of reduced mortality, morbidity, and reduced magnitude of allogeneic blood transfusions. CONCLUSION: Use of HBC in proximal aortic surgery resulted in reduced bleeding and blood transfusion, improving clinical outcomes. Undoubtedly, multiple factors account for the overall improved results. However, use of HBC is an important component of an overall blood conservation strategy.

Aortic Dissection↗

PubMedDate not supplied

Retroperfusion and balloon support to improve coronary revascularization.

Coronary venous retroperfusion and Intra-Aortic Balloon Pump (IABP) support are methods currently utilized to reduce ischemic damage prior to revascularization of acutely ischemic myocardium. This study was undertaken to determine whether combining coronary venous retroperfusion using Pressure Controlled Intermittent Coronary Sinus Occlusion (PICSO) with the IABP would result in improved salvage of ischemic myocardium. In 40 adult pigs, the second and third diagonal vessels were occluded with snares for 1 1/2 hours followed by 1/2 hours of cardioplegic arrest and 3 hours of reperfusion with the snares released. During the period of coronary occlusion prior to arrest, 10 pigs received the IABP, 10 had PICSO, 10 had PICSO+IABP, while 10 had no intervention (Unmodified). Ischemic damage was assessed by echocardiographic wall motion scores, myocardial pH, and the area of necrosis/area of risk using histochemical staining. Both PICSO and the IABP alone significantly reduced ischemic damage. However, the best wall motion scores, highest pH, and least necrosis was seen in the IABP+PICSO group. We conclude that the combination of coronary venous retroperfusion using PICSO and the IABP results in the most optimal recovery of acutely ischemic myocardium during emergent surgical revascularization.

Animals↗