Development of rotary blood pump technology: past, present, and future

Even though clinical acceptance of a nonpulsatile blood flow was demonstrated almost 45 years ago, the development of a nonpulsatile blood pump was completely ignored until 20 years ago. In 1979, the first author's group demonstrated that completely pulseless animals did not exhibit any abnormal physiology if 20% higher blood flows were provided to them. However, during the next 10 years (1979-1988), minimum efforts were provided for the development of a nonpulsatile, permanently implantable cardiac prosthesis. In 1989, the first author and his team at Baylor College of Medicine initiated a developmental strategy of various types of nonpulsatile rotary blood pumps, including a 2-day rotary blood pump for cardiopulmonary bypass application, a 2 week pump for ECMO and short-term circulatory assistance, a 2 year pump as a bridge to transplantation, and a permanently implantable cardiac prosthesis. Following the design and developmental strategy established in 1989, successful development of a 2-day pump (the Nikkiso-Fairway cardiopulmonary bypass pump) in 4 years (1989-1993), a 2 week pump (Kyocera gyro G1E3 pump) in 6 years (1992-1998), and a bridge to transplant pump (DeBakey LVAD-an axial flow blood pump) in 10 years (1988-1998) was made. Currently, a permanently implantable centrifugal blood pump development program is successfully completing its initial Phase 1 program of 5 years (1995-2000). Implantation exceeded 9 months without any negative findings. An additional 5 year Phase II program (2000-2005) is expected to complete such a device that will be clinically available.     

Sequential drain amylase to guide drain removal following pancreatectomy

Background

Although used as criterion for early drain removal, postoperative day (POD) 1 drain fluid amylase (DFA) ≤ 5000 U/L has low negative predictive value for clinically relevant postoperative pancreatic fistula (CR-POPF). It was hypothesized that POD3 DFA ≤ 350 could provide further information to guide early drain removal.

The DeBakey classification exactly reflects late outcome and re-intervention probability in acute aortic dissection with a slightly modified type II definition

Objective: The DeBakey classification was used to discriminate the extent of acute aortic dissection (AD) and was correlated to long-term outcome and re-intervention rate. A slight modification of type II subgroup definition was applied by incorporating the aortic arch, when full resectability of the dissection process was given. Methods: Between January 2001 and March 2010, 118 patients (64% male, mean age 59 years) underwent surgery for acute AD. As many as 74 were operated on for type I and 44 for type II AD. Complete resection of all entry sites was performed, including antegrade stent grafting for proximal descending lesions. Results: Patients were comparable with respect to demographics and preoperative hemodynamic status. They underwent isolated ascending replacement, hemiarch, or total arch replacement in 7%, 26%, and 67% in type I, versus 27%, 37%, and 36% in type II, respectively. Additional descending stent grafting was performed in 33/74 (45%) type I patients. In-hospital mortality was 14%, 16% (12/74) in type I versus 9% (4/44, type II), p = 0.405. After 5 years, the estimated survival rate was 63% in type I versus 80% in type II, p = 0.135. In type II, no distal aortic re-intervention was required. In type I, the freedom of distal re-interventions was 82% in patients with additional stent grafting versus 53% in patients without, p = 0.022. Conclusions: The slightly modified DeBakey classification exactly reflects late outcome and aortic re-intervention probability. Thus, in type II patients, the aorta seems to be healed without any probability of later re-operation or re-intervention.     

Team-based simulations for new surgeons: Does early and often make a difference?

Background

Current work hour restrictions and the expansion of requirements for surgery residents has led to decreased time on high-acuity rotations such as trauma and acute care surgery. In an effort to improve resident competency, we examined the efficacy of a new team-based trauma curriculum for postgraduate year 1 (PGY1) residents.

Aortic dissection in the elderly

To analyze the characteristics of aortic dissection in the elderly, we reviewed 168 cases from January 1999 to September 2005 in a medical center in Taiwan. Fifty-six cases were suitable for enrollment in our study. Of these, 44 (79%) were male and 12 (21%) were female; ages ranged from 29 to 92 years, with a mean of 61 +/- 11.75 years. We defined elderly as age >/= 65 years. There was no obvious discrepancy between age and types of aortic dissections involved (p = 0.726). The elderly had the lower mean systolic blood pressure (166.4 mm Hg) upon arrival at the Emergency Department (p = 0.002). Presentation to the Emergency Department with chest pain or chest tightness was more commonly seen in the elderly (66.7%) (p = 0.042). The mean hospital stay was 12.6 +/- 0.5 days, and it was longer in the elderly group (12.96 days) (p = 0.009). Otherwise, the mortality rate was 6.7% +/- 3.6%. We found a lower mortality rate in the elderly than in the younger group (4% vs. 9%, respectively; p = 0.008).     

Unusual complication of aortic dissections: intimo–intimal intussusception

Angiography with a pre-diagnosis of acute coronary syndrome was performed in a 76-year-old female patient presenting to another hospital with symptoms of chest pain and syncope. Upon determination of type III aortic dissection, the patient was referred to our clinic. On CT angiography, the ascending aortic diameter was 57 mm and no dissection flap was observed. There was a filling defect suggestive of intimo–intimal intussusception at the level of the aortic arch, occlusion of the left arteria carotid communis, and a double-channel aorta extending from the left subclavian artery to the iliac artery. On transoesophageal echocardiography, the ascending aorta was seen to be larger than normal and no dissection flap was observed. There were findings suggestive of haematoma and intimo–intimal intussusception at the proximal part of the aortic arch. The dissection flap causing occlusion in the vascular structures was resected. Supracoronary graft replacement of the ascending aorta was performed. Transoesophageal echocardiography is an invasive investigative method with high sensitivity and specificity for the diagnosis of intimo–intimal intussusception.     

Extensive replacement of the aorta from the ascending aorta to the supraceliac abdominal aorta during a one-stage operation

A successful replacement of the aorta from the ascending aorta to the supraceliac abdominal aorta in one operation is herein reported. The patient was 66-year-old woman who had DeBakey type I chronic aortic dissection with a pre-disseminated intravascular coagulation (DIC) condition. The image diagnosis revealed a markedly enlarged false lumen with a narrow true lumen in the ascending aorta extending to the diaphragm level while below the diaphragm level, the aortic dilatation was mild. The operation was performed through both a thoracoabdominal incision and a median sternotomy to expose the whole thoracic aorta, and the aorta was replaced from the ascending aorta to the supraceliac abdominal aorta. Selective cerebral perfusion was used for cerebral protection and this was a useful adjunct since no time limitations were thus required during repair of the aortic arch. Although the patient developed several complications postoperatively, she eventually recovered and was discharged from the hospital without any neurological disorders.     

Occlusion of the abdominal aorta caused by enlargement of the false lumen after graft replacement for a DeBakey type IIIb dissecting aneurysm: Report of a case

(Received for publication on July 10, 1997; accepted on Mar. 10, 1998)     

Rivastigmine reduces “likely to use methamphetamine” in methamphetamine-dependent volunteers

We previously reported that treatment with the cholinesterase inhibitor rivastigmine (3 mg, PO for 5 days) significantly attenuated “Desire for METH”. Given that higher dosages of rivastigmine produce greater increases in synaptic ACh, we predicted that 6 mg should have more pronounced effects on craving and other subjective measures. In the current study, we sought to characterize the effects of short-term exposure to rivastigmine (0, 3 or 6 mg) on the subjective and reinforcing effects produced by administration of methamphetamine (METH) in non-treatment-seeking, METH-dependent volunteers. This was a double-blind, placebo-controlled, crossover study. Participants received METH on day 1, and were then randomized to placebo or rivastigmine on day 2 in the morning and treatment continued through day 8. METH dosing was repeated on day 6. The data indicate that METH (15 and 30 mg), but not saline, increased several positive subjective effects, including “Any Drug Effect”, “High”, “Stimulated”, “Desire METH”, and “Likely to Use METH” (all p's < 0.0001). In addition, during self-administration sessions, participants were significantly more likely to choose METH over saline (p < 0.0001). Evaluating outcomes as peak effects, there was a trend for rivastigmine to reduce “Desire METH” (p = 0.27), and rivastigmine significantly attenuated “Likely to Use METH” (p = 0.01). These effects were most prominent for rivastigmine 6 mg when participants were exposed to the low dose (15 mg, IV), but not high dose (30 mg, IV), of METH. The self-administration data reveal that rivastigmine did not alter total choices for METH (5 mg, IV/choice). Overall, the results indicate some efficacy for rivastigmine in attenuating key subjective effects produced by METH, though additional research using higher doses and longer treatment periods is likely needed. These data extend previous findings and indicate that cholinesterase inhibitors, and other drugs that target acetylcholine systems, warrant continued consideration as treatments for METH dependence.