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Biomedical subjects

M R Petracek

Publications and source records attributed to M R Petracek.

At least 19 recordsLinked to original sources
PubMed2001

Clinical outcomes after aortic valve replacement with the Toronto stentless porcine valve.

BACKGROUND: Hemodynamic benefits of the Toronto stentless porcine valve have been documented. Clinical well-being and freedom from major valve-related events have been less well defined. METHODS: A total of 447 patients were prospectively followed for up to 8 years (1,745.2 valve years total, 3.9 valve years/patient). The patient demographics included 66% men, mean age 65 years, New York Heart Association functional class III-IV 55%, concomitant coronary artery bypass grafting 41%. RESULTS: We found that 83.7% of patients were in New York Heart Association functional class I and 80.8% had 0 to 1+ aortic insufficiency. Mean gradient at 6 years (n = 75) was 4.4 mm Hg and mean effective orifice area (EOA) 2.4 cm2. Late adverse event rates per patient per year were: embolism 1.0%, endocarditis 0.4%, thrombosis 0%, structural deterioration 0.2%, explant 0.3%, and valve-related death 0.6%. Freedom from valve-related death at 6 years was 95.8%; from cardiac death 96.3%. Freedom from endocarditis was 98.4%, from embolism 93.9%, from structural deterioration 97.4%, and freedom from explant 98.1%. For patients older than 60 years, freedom from structural deterioration was 100%. CONCLUSIONS: These results confirm satisfactory clinical outcomes after aortic valve replacement with the Toronto stentless porcine valve, with a low incidence of valve-related adverse events as long as 96 months after valve replacement.

Adult↗
PubMed1999

Comparison of transmyocardial revascularization with medical therapy in patients with refractory angina.

BACKGROUND: Transmyocardial revascularization involves the creation of channels in the myocardium with a laser to relieve angina. We compared the safety and efficacy of transmyocardial revascularization performed with a holmium laser with those of medical therapy in patients with refractory class IV angina (according to the criteria of the Canadian Cardiovascular Society). METHODS: In a prospective study conducted between March 1996 and July 1998 at 18 centers, 275 patients with medically refractory class IV angina and coronary disease that could not be treated with percutaneous or surgical revascularization were randomly assigned to receive transmyocardial revascularization followed by continued medical therapy (132 patients) or medical therapy alone (143 patients). RESULTS: After one year of follow-up, 76 percent of the patients who had undergone transmyocardial revascularization had improvement in angina (a reduction of two or more classes), as compared with 32 percent of the patients who received medical therapy alone (P<0.001). Kaplan-Meier survival estimates at one year (based on an intention-to-treat analysis) were similar for the patients assigned to undergo transmyocardial revascularization and those assigned to receive medical therapy alone (84 percent and 89 percent, respectively; P=0.23). At one year, the patients in the transmyocardial-revascularization group had a significantly higher rate of survival free of cardiac events (54 percent, vs. 31 percent in the medical-therapy group; P<0.001), a significantly higher rate of freedom from treatment failure (73 percent vs. 47 percent, P<0.001), and a significantly higher rate of freedom from cardiac-related rehospitalization (61 percent vs. 33 percent, P<0.001). Exercise tolerance and quality-of-life scores were also significantly higher in the transmyocardial-revascularization group than in the medical-therapy group (exercise tolerance, 5.0 MET [metabolic equivalent] vs. 3.9 MET; P=0.05); quality-of-life score, 21 vs. 12; P=0.003). However, there were no differences in myocardial perfusion between the two groups, as assessed by thallium scanning. CONCLUSIONS: Patients with refractory angina who underwent transmyocardial revascularization and received continued medical therapy, as compared with similar patients who received medical therapy alone, had a significantly better outcome with respect to improvement in angina, survival free of cardiac events, freedom from treatment failure, and freedom from cardiac-related rehospitalization.

Aged↗
PubMed1999

Use of Toronto stentless porcine valve in patients with aortic dilation.

One of the contraindications for a stentless aortic valve is dilation of the aorta such that the sinotubular ridge is more than 2 mm larger than the annulus. Since May of 1994, 134 patients have had their aortic valve replaced with St Jude Toronto SPV valves; of these, 38 patients have required sinotubular ridge reduction. This was done by using one or more pleats in the aorta between the commisural posts. There were 20 patients with one pleat, 12 patients with two pleats, 5 patients with three pleats, and 1 patient with four pleats. In addition, three Toronto SPV valves were used in patients with significant calcification in the native coronary sinuses. All of the valves have had trace or no aortic insufficiency and have not developed aortic insufficiency in follow-up evaluation. Mean gradients remain low (<10 mm Hg). These valves have been much more versatile than originally expected and can be used in patients with mild to moderate aortic dilation and calcification.

Aged↗
PubMed1998

Transmyocardial revascularization in patients with refractory, unstable angina.

BACKGROUND: Previous reports of transmyocardial revascularization (TMR) indicate a significant mortality in patients with refractory, unstable angina. We hypothesized that TMR with a holmium laser would result in significant angina relief with acceptable mortality in this patient population. METHODS AND RESULTS: Patients were defined as unstable if they were unweanable from intravenous antianginal medications or were too unstable for a persantine thallium scan. Patients had a left ventricular ejection fraction (LVEF) of > 25% and were not amenable to CABG or PTCA. Before treatment, all patients had class IV angina. TMR was performed in 85 patients, with a mean of 35 +/- 11 transmural laser channels. Mean age was 63 +/- 10 years. Mean LVEF was 48 +/- 11%. Of these patients, 79% were men. Prior CABG and/or PTCA had been performed in 87% of patients, and 72% of patients had a history of prior MI. Operative mortality was 12% (10 of 85). There were 2 deaths between discharge and 3 months after surgery and 7 late deaths from 6 to 12 months after surgery. Twelve-month mortality was 22.4% (19 of 85). At 3 months, 86% of patients had class II angina or better. At 6 and 12 months, 77% and 75% of patients, respectively, had class II angina or better. Mean angina class at 6 and 12 months' follow-up was 1.5 +/- 1.1 and 1.6 +/- 1.3, respectively. CONCLUSIONS: In patients with refractory unstable angina, TMR with a holmium laser provided significant angina relief. Moreover, 30-day operative mortality and 12-month mortality were acceptable, especially given this subset of unstable patients with refractory angina.

Aged↗
PubMed1994

Ventricular aneurysmectomy. A 25-year experience.

OBJECTIVE: This study determined predictors of operative survival and improved long-term outcomes in patients undergoing ventricular aneurysmectomy. SUMMARY BACKGROUND DATA: Since the first successful repair of ventricular aneurysm in 1958, refined technique and improvement in perioperative care have been introduced to lower morbidity and mortality. METHODS: The authors reviewed their institutional experience from 1968 through 1993 in treating 523 patients who underwent ventricular aneurysmectomy. RESULTS: Overall operative mortality was 8% and overall median survival was 128 months. Contractility grade, age, and year of operation were predictors of operative mortality and of improved long-term survival. Type of aneurysm repair was not a strong predictor of operative mortality or improved long-term survival. CONCLUSIONS: Ventricular aneurysmectomy can be performed safely using one of a number of established techniques, although operative mortality and long-term survival may not depend on the techniques used.

Adult↗
PubMed1992

Videothoracoscopy: improved technique and expanded indications.

Current videoendoscopic technology and percutaneous techniques of exposure and dissection have been successfully applied to abdominal surgery with favorable results. Application of this technology to our practice of thoracoscopy is the basis of this report. Videothoracoscopy has been performed in 39 patients for the following indications: chronic pleural effusion, interstitial lung disease, mediastinal lymphadenopathy in lung cancer, persistent air leak after decortication, mediastinal mass, recurrent spontaneous pneumothorax, hydropneumothorax with persistent air leak, and pleural-based mass. The technique we employ includes lateral decubitus positioning and double-lumen endotracheal intubation with ipsilateral lung collapse. The videoscope, retractors, and instruments are introduced through separate 10-mm incisions. Percutaneous manipulation of instruments and the videoscope is guided by images produced on television screens without dissection, and if resection is performed, the incision is enlarged to allow specimen retrieval. Procedures performed using this technique include pleural biopsy, partial pleurectomy, lysis of adhesions, lung biopsies, staging lymph node biopsy, lung nodule biopsy, pleural-based mass resection, and mediastinal mass biopsy and resection. This videoendoscopic technique greatly improves visualization of thoracic anatomy, facilitating thoracoscopy and enhancing exploration of the chest. It is preferred over conventional thoracoscopy and, in some patients, reduces the magnitude of operation by avoiding thoracotomy.

Adult↗
PubMed1991

Internal mammary artery graft at reoperation: risks, benefits, and methods of preservation.

To determine the effect of a prior internal mammary artery (IMA) graft on coronary artery bypass reoperation (CABR), we reviewed our experience with 410 consecutive patients: 313 received only saphenous vein grafts at initial coronary artery bypass grafting (CABG), and 97 received at least one IMA graft at CABG. Cardiac catheterization data before CABG were available in 110 patients (56 received only saphenous vein grafts, 54 received at least one IMA graft), allowing comparison of left ventricular function at CABG and CABR. Injury of the IMA graft occurred in 5 patients (1 death), but presence of an IMA graft was not an independent predictor of morbidity or mortality. Overall, the incidences of complications and deaths were higher in patients with saphenous vein grafts than in patients with IMA grafts, though not significantly so. Internal mammary artery grafts better preserved cardiac function: patients with IMA grafts had worse left ventricular function before CABG but better left ventricular function before CABR than patients with saphenous vein grafts. Left ventricular function deterioration from before CABG to before CABR was significantly less in patients with IMA grafts. We conclude that the risk of CABR is not increased by a previously constructed IMA graft and that left ventricular function is better preserved at CABR when an IMA graft was constructed at the initial operation.

Confounding Factors, Epidemiologic↗
PubMed1988

Influence of preoperative showers on staphylococcal skin colonization: a comparative trial of antiseptic skin cleansers.

We undertook a prospective randomized observer-blinded study comparing the ability of preoperative showers with chlorhexidine gluconate (Hibiclens), povidone-iodine (Betadine), and a lotion soap (Safe 'N Sure) to diminish the staphylococcal skin flora of patients. By block randomization, patients scheduled for an elective cardiac operation or coronary artery angioplasty were assigned to shower with one of the study skin cleansers either once (evening only) or twice (both evening and morning) before the procedure. Semiquantitative samples for culture were obtained from the subclavian and inguinal sites on the evening before the procedure (baseline culture) and again the next morning before the operation. The chlorhexidine skin cleanser consistently reduced staphylococcal colony counts at both the subclavian and inguinal sites before the procedure. This reduction was significant for patients showering both evening and morning (p less than 0.05). The use of the povidone-iodine skin cleanser inconsistently affected skin flora. Patients using lotion soap either experienced no change or had an increase in colony counts. Chlorhexidine is more effective than povidone-iodine in diminishing skin colonization with staphylococci in patients before operation. Repeated applications of chlorhexidine are superior to a single shower with this agent.

Anti-Infective Agents, Local↗
PubMed1987

Efficacy of cefazolin, cefamandole, and gentamicin as prophylactic agents in cardiac surgery. Results of a prospective, randomized, double-blind trial in 1030 patients.

In an effort to develop an improved regimen of antibiotic prophylaxis in cardiac surgery, 1030 patients who were to have elective cardiothoracic surgery involving a median sternotomy were selected at random to receive cefamandole or cefazolin, with or without gentamicin, in a prospective double-blind study. Cefazolin was significantly less effective than cefamandole at both the sternal (1.8% vs. 0.4%, respectively, p less than 0.05) and donor sites (1.3% vs. 0%, respectively, p less than 0.02). Seven Staphylococcus aureus infections occurred among cefazolin recipients as compared with no such infections among the patients receiving cefamandole (p less than 0.01). All five wound infections yielding fungi or gentamicin-resistant gram-negative rods occurred in patients who had received gentamicin as a second prophylactic agent. These data suggest that gentamicin has no role as a prophylactic antibiotic in cardiac surgery and that, compared with cefamandole, cefazolin offers unreliable prophylaxis against deep infection at both the sternal and donor sites.

Cardiac Surgical Procedures↗
PubMed1986

Internal mammary artery grafts: technical factors influencing patency.

Eight hundred fourteen patients with internal mammary artery (IMA) coronary artery bypass grafts have been restudied 961 times with coronary arteriography, primarily to evaluate the patency of the grafts in the setting of symptomatic coronary occlusive disease. Their records were reviewed to assess graft patency as related to the technical aspects of coronary artery bypass surgery. Patency was evaluated using life-table analysis of the data. The method of harvesting the IMA played no role in patency. The left anterior descending coronary artery was the recipient coronary artery with the highest patency rate. The left IMA had a significantly higher patency rate than the right IMA. As a group, the IMAs had a significantly higher patency rate than saphenous vein grafts. However, there was no difference between right IMA grafts and saphenous vein grafts. The mammary artery grafts that remained patent throughout the study had a significantly higher blood flow after bypass than did those that became occluded (43.0 +/- 0.9 versus 28.9 +/- 1.8 ml/min; p less than .001).

Blood Flow Velocity↗
PubMed1985

Cryoprecipitate-topical thrombin glue. Initial experience in patients undergoing cardiac operations.

The use of fibrin glues as topical hemostatic agents is reported in the European literature. We have composed an analogous compound in our operating rooms using cryoprecipitate and topical thrombin (1000 units/ml) in equal volumes applied directly to the bleeding site. We have used cryoprecipitate-topical thrombin glue in 26 patients undergoing cardiac operations. Severe bleeding not responding to usual methods of control was encountered during or after coronary artery bypass (n = 17), valve replacement (n = 3), bypass plus valve replacement (n = 5), or repair of postinfarction ventricular septal defect (n = 1). Five patients were operated on emergently and four were undergoing their second cardiac operation. The glue was used in four patients while on bypass and fully heparinized and in 17 patients who continued to bleed after separation from bypass and administration of protamine. Hemostasis was achieved in all patients and none required reexploration for bleeding. In five patients undergoing reexploration for postoperative hemorrhage (none having received cryoprecipitate-topical thrombin glue during the initial operation), the glue provided hemostasis when other measures failed, and no additional reexplorations were needed. No patient exhibited hypersensitivity, fibrinolysis, or coagulopathy following the use of this glue. In 16 patients followed for 9 to 12 months postoperatively, no hepatitis has occurred. The highly concentrated fibrinogen in cryoprecipitate is activated by thrombin to form fibrin and bring about rapid hemostasis. Cryoprecipitate-topical thrombin glue is a readily available, reliable, and inexpensive topical hemostatic agent in the patient undergoing a cardiac operation.

Cardiac Surgical Procedures↗
PubMed1984

The fate of arm veins used for aorta-coronary bypass grafts.

Arm veins have been a common second choice conduit for those patients having insufficient saphenous veins for coronary bypass operations. To define the patency and durability of arm vein grafts, we reviewed our patients with one or more arm vein grafts used for coronary revascularization between 1974 and 1982. A total of 59 patients required at least one arm vein graft and 51 are presently alive. Postoperative arteriograms were obtained in 28 patients. Of 56 arm vein grafts used, 32 (57%) were patent and 24 (43%) had failed at 2 years. Seven of the patent grafts had a localized area of stenosis. Sixteen internal mammary artery grafts also had been used in this group of patients, and 15 (93%) were patent. We conclude that arm vein grafts have a high failure rate and are not as dependable as saphenous vein grafts or internal mammary artery grafts.

Adult↗
PubMed1982

Surgical procedures after percutaneous transluminal coronary angioplasty.

Since Gruentzig's introduction of percutaneous transluminal coronary angioplasty in 1974, there has been increasing clinical use of this technic. At St. Thomas Hospital in Nashville, 50 patients were selected for coronary angioplasty through December 1981. Twenty of the 50 have ultimately had coronary artery bypass surgery. Excellent dilatation of the selected coronary artery was accomplished in 19 patients. Fair dilatation was achieved six times, and four of these patients have had elective coronary artery bypass surgery. In 18 patients the vessels could not be dilated, and 12 of this group had coronary artery bypass, three on an urgent basis. In the remaining seven patients, the affected coronary stenosis was converted to 100% occlusion during the angioplasty, resulting in four emergency operations and one death. It appears that percutaneous transluminal coronary angioplasty is not as easy to master as had been anticipated, and that the results are just good enough in our hands to justify perseverence.

Angioplasty, Balloon↗
PubMed1981

Three simple solutions for renal flush and preservation.

The harvesting of kidneys at small hospitals where standard flush solutions are not available has led to the use of several flush solutions that can be made from readily available materials. Mongrel dogs (15) had bilateral nephrectomy after receiving intravenously a mixture of Ringer's lactate, furosemide (Lasix), mannitol, and chlorpromazine (Thorazine). One kidney was perfused with iced Collins' solution and stored for 24 hours, submerged in the perfusate at 4 C. Five dogs each had the contralateral kidney perfused with a solution of either (1) Ringer's lactate, salt-poor albumin, and heparin; (2) 6% dextran 70 and Fenwall buffered heparin solution; or (3) Ringer's lactate, mannitol, and heparin, and were stored in their respective perfusate. After 24 hours' storage the kidneys were transplanted into the neck, and creatinine clearance (Crcl) was determined on days 1, 2, 3, 5, and 7. The dogs were sacrificed on day 7 and biopsy specimens were obtained from each kidney for pathologic examination. The kidneys perfused with Collins' solution had immediate function after transplantation with an average Crcl of 10.5 at 25 hours and 20.2 at seven days. The kidneys perfused with Ringer's lactate and albumin had minimal function immediately after transplantation and were anuric within 24 hours. The kidneys perfused with dextran solution and Ringer's lactate and mannitol solution had immediate function but output remained low, and by seven days the average Crcl was only 3.0 and 4.5 respectively. All solutions except the Ringer's lactate and albumin were hyperosmolar, thus helping to prevent the "no reflow" phenomenon. These results indicate that the solutions tested do not result in the adequate preservation to warrant clinical use.

Animals↗
PubMed1980

Resection of abdominal aortic aneurysms in the over-80 age group.

We reviewed the risk of resecting an abdominal aortic aneurysm in 38 patients aged 80 years or older. The operative mortality for an elective aneurysm was 5.2%, for symptomatic but nonruptured aneurysm 26.6%, and for ruptured aneurysm 66.7%. The preoperative risk factors were essentially the same for the elective and ruptured group. Several of the patients with ruptured aneurysm had been followed up with their aneurysm for several years by nonsurgeons. To better understand why these patients were not being referred for elective repair, 100 nonsurgeons were sent a questionnaire concerning abdominal aortic aneurysms in octogenarians. The results showed that 81% overestimated the elective operative mortality and as a result did not recommend elective resection.

Aged↗