Search PubMed⌕ Search

Biomedical subjects

R M Kass

Publications and source records attributed to R M Kass.

At least 55 records · Page 3Linked to original sources
PubMed1994

Utility of inhaled pentamidine prophylaxis in lung transplant recipients.

The incidence of Pneumocystis carinii pneumonia (PCP) has been shown to be high posttransplantation in the absence of prophylaxis. For this reason, lung transplant recipients routinely receive prophylaxis. We report on our results using aerosolized pentamidine prophylaxis in nine patients post-lung transplantation (eight single lung transplants, one double). The patients received monthly treatments of 300 mg of aerosolized pentamidine for a mean of 10.6 months (range, 4 to 21 months). Patients were routinely monitored with serial pulmonary function studies and bronchoscopy as clinically indicated. Two of the patients experienced bronchospasm in response to the therapy. None of the patients experienced any episodes of PCP during the period of inhaled pentamidine prophylaxis. Inhaled pentamidine is a safe and effective form of PCP prophylaxis and may be used instead of sulfamethoxazole-trimethoprim in patients who have a sulfa allergy or other untoward sulfa side effects.

Administration, Inhalation↗
PubMed1993

Relation between upper limit of vulnerability and defibrillation threshold in humans.

BACKGROUND: In the canine model, an upper limit of shock strength exists that can induce ventricular fibrillation during the vulnerable period of the cardiac cycle. This shock strength (the upper limit of vulnerability) closely correlates with the defibrillation threshold and supports the "upper limit of vulnerability" hypothesis of defibrillation. It is not known whether an upper limit of vulnerability exists in humans or whether this limit correlates with the defibrillation threshold. METHODS AND RESULTS: In 13 patients undergoing implantable cardioverter-defibrillator implantation, the shock strengths associated with a 50% probability of reaching the upper limit of vulnerability (ULV50) and a 50% probability of reaching the defibrillation threshold (DFT50) were determined by the up-down algorithm. The ULV50 was determined only for the mid-upslope of the positive T waves and for the mid-downslope of the negative T waves. No major complications occurred during surgery. An upper limit of vulnerability was demonstrated in each patient. The ULV50 was 300 +/- 138 V or 6.8 +/- 5.8 J, which was significantly lower than the DFT50 of 347 +/- 167 V (p = 0.038) or 9.1 +/- 7.3 J (p = 0.013). The correlation between the ULV50 and the DFT50 was significant (r = 0.90, p < 0.001 for voltage; r = 0.93, p < 0.001 for energy). CONCLUSIONS: An upper limit of vulnerability is present in humans. There is a significant correlation between the ULV50 and the DFT50, and the ULV50 is significantly lower than the DFT50.

Algorithms↗
PubMed1993

Hemodynamic responses to exercise after lung transplantation.

A reduced exercise tolerance, maximum oxygen uptake (VO2max), and anaerobic threshold have been reported after lung transplantation (LT). We prospectively assessed the hemodynamic responses to incremental cycle ergometry before and after LT in eight recipients. All recipients underwent a 6-week formal exercise training program. The VO2max increased after versus before LT (13.4 +/- 0.8 vs 9.2 +/- 0.8 ml/min/kg) (p < 0.01). No transition thresholds by analysis of arterial standard bicarbonate were discerned before LT, while the thresholds after LT were abnormally low (VO2 = 9.4 +/- 0.6 ml/min/kg or 35 +/- 3 percent of predicted maximum VO2). An early rise in arterial lactate was similarly observed after LT. Maximum stroke volume index increased in six of seven patients after versus before LT (51 +/- 4 vs 37 +/- 2 ml/beat/m2) (p < 0.05). Three patients demonstrated an increased mean pulmonary arterial pressure at rest, while pressures during exercise were elevated in six. Pulmonary vascular resistance was mildly elevated after LT but decreased appropriately during incremental exercise and was associated with normal cardiac output responses. We conclude that pulmonary vascular abnormalities occurred during hemodynamic exercise testing in the majority of LT recipients; however, exercise limitation was primarily attributed to cardiovascular limitation or to deconditioning in five of the recipients. In the remaining three, the exercise study was considered to be submaximal by virtue of low peak heart rates. A persistent state of deconditioning may have important implications with respect to exercise training regimens after LT.

Adult↗
PubMed1992

Results of early repair of ventricular septal defect after an acute myocardial infarction.

A 10-year experience with early operation for postinfarction ventricular septal defect is reviewed. Twenty-two patients underwent surgical repair; operative mortality was 36% (< 30 days). The actuarial survival was 64% at 1 month, 59% at 1 year, and 47% at 5 years. Risk factors predictive of operative mortality were diabetes (p = 0.001), elevated preoperative right atrial pressure (p = 0.02), the absence of a preoperative intraaortic balloon pump (p = 0.006), and a short time interval between infarct and operation (p = 0.018). Long-term survival was adversely related to diabetes (p = 0.030), elevated preoperative right atrial pressure (p = 0.005), and, surprisingly, survival was better in patients with a greater extent of coronary artery disease (p = 0.023). There were 14 operative survivors (64%) and 11 long-term survivors (3 months to 10 years, mean 6.0 +/- 3.5 years). Six of eleven survivors were in functional New York Heart Association class I, one was in class II, and four were in class III.

Aged↗
PubMed1992

Comparative efficacy of ring and suture annuloplasty for ischemic mitral regurgitation.

BACKGROUND: Patients with ischemic mitral regurgitation (MR) represent a therapeutic challenge, and results after combined valve replacement and revascularization have been poor. Valve repair is a promising approach, but the optimal method of repair is not known. METHODS AND RESULTS: In 60 patients with coronary artery disease and 3+ or 4+ MR, we used intraoperative Doppler echocardiography to study the efficacy of Carpentier-Edwards ring (n = 27) and commissural suture (n = 33) annuloplasty. Patients with ruptured papillary muscles, torn chordae, and ballooning or scalloping of the leaflets were excluded. Ring and suture groups were similar in preoperative ejection fraction (35 +/- 14% and 34 +/- 17%), MR grade (3.5 +/- 0.5 and 3.4 +/- 0.6), and acuity of MR (41% and 33% acute) (p = NS). Postoperatively, the ring group achieved a lower residual MR grade than the suture group (0.5 +/- 0.5 versus 1.5 +/- 1.1; p < 0.001), and the mitral annular diameter was reduced to a greater extent in the ring group (by 1.5 +/- 0.5 cm versus 0.5 +/- 0.4 cm; p < 0.001). Success (> or = 2 grade MR reduction) was more frequent in the ring than in the suture group (96% versus 67%, p < 0.01). One-year survival was similar (74 +/- 9% ring, 71 +/- 8% suture). Follow-up Doppler studies showed a higher mean gradient (4.0 +/- 1.2 mm Hg) and smaller valve area (2.1 +/- 0.5 cm2) in the ring group, but the postoperative New York Heart Association class was similar in both groups (83% versus 74% class I-II). CONCLUSIONS: Ring annuloplasty provides a more effective reduction of ischemic MR and a higher success rate than the suture technique. This may be related to uniform rather than localized shortening of the annulus and a greater reduction in annulus diameter.

Aged↗
PubMed1991

Morbidity and mortality after coronary artery bypass in octogenarians.

One hundred fifty seven consecutive octogenarians (mean age +/- standard deviation, 82.4 +/- 1.9 years) underwent coronary artery bypass grafting with hypothermia (mean temperature, 21.8 degrees +/- 1.8 degrees C), hyperkalemic cardioplegia, and cardiopulmonary bypass in a 9-year period. Sixty-six percent were male. Preoperatively, 115 patients (73%) were in New York Heart Association functional class IV, with the remainder being in either class III (23%) or class II (4%). Twenty percent of the patients had major complications including postoperative hemorrhage (15), sepsis (9), cerebrovascular accident (6), third-degree heart block (5), renal failure requiring dialysis (1), and pulmonary embolism (1). The 30-day or in-hospital mortality rate was 7.0%. Mean total hospital stay was 26.1 +/- 17.9 days. One-year and 5-year actuarial survival rates were 85% and 62%, respectively. Higher mortality was seen to be associated with New York Heart Association class IV, left ventricular ejection fraction less than 0.40, and lesser values for cardiac output and cardiac index. At the 6-month postoperative follow-up, 73% of the survivors reported that their general health had improved as compared with before operation. This experience demonstrates that for select octogenarians with unmanageable angina pectoris, coronary artery bypass grafting is an effective therapeutic option.

Aged↗
PubMed1990

Ten-year experience with the St. Jude Medical valve for primary valve replacement.

The St. Jude Medical valve is a bileaflet prosthesis with excellent hemodynamic characteristics, but the long-term surgical experience with this valve, its durability, and its biocompatibility are unknown. During a 10-year period from March 1978 to 1988, 690 prostheses (290 aortic, 252 mitral, and 74 double aortic-mitral) were inserted as the initial valve replacement substitute in 616 patients (mean age 63 years). Coronary atherosclerosis was present in 58%. Follow-up totaled 2031 patient-years (mean 3.3 years) and was 95% complete (32 lost). Early (30-day) mortality rates were 5.2%, 11.9%, and 8.1% after aortic, mitral, and double valve replacement; 5- and 9-year actuarial survival rates were 71% +/- 3% and 51% +/- 8%, 59% +/- 4% and 41% +/- 6%, and 69% +/- 6% and 47% +/- 15%, respectively. Deaths were associated with extensive coronary atherosclerosis (p less than 0.001), older age (p less than 0.001), advanced preoperative New York Heart Association functional class (p less than 0.05), and malignant ventricular arrhythmias (p less than 0.05). No structural failures have been observed. Embolism (40 events) occurred at a rate of 2.0%/pt-yr (2.3% aortic, 1.6% mitral, 2.0% double). There were six cases of valve thrombosis (0.3%/pt-yr; one fatal). Hemorrhage was the most frequent complication (2.6%/pt-yr); 13 (25%) of 52 events were fatal, accounting for 62% of all valve-related deaths. After the target prothrombin time ratio was lowered, the rate of hemorrhage decreased by 44% (2.7% to 1.5%/pt-yr), while the combined rate of embolism and valve thrombosis increased slightly (2.2% to 2.5%/pt-yr, a 14% change). In summary, the St. Jude Medical valve remains a durable valve substitute. Survival was strongly related to the presence of associated coronary atherosclerosis. The most common complication has been hemorrhage; a less intensive warfarin regimen may reduce hemorrhagic risk while maintaining thromboembolic protection.

Adolescent↗
PubMed1987

Intraoperative Doppler color flow mapping for assessment of valve repair for mitral regurgitation.

The ability of color Doppler flow mapping to provide intraoperative information about mitral regurgitation (MR) severity and to evaluate adequacy of mitral valve repair was assessed by performing color Doppler echocardiography immediately before and after cardiopulmonary bypass, with the transducer placed directly on the epicardium. In 56 patients, the degree of MR by intraoperative color Doppler correlated well with left ventricular angiography (kappa = 0.80) and with closed-chest preoperative color Doppler (kappa = 0.84) and had good interobserver reproducibility (kappa = 0.88). Good correlation was also seen between closed-chest color Doppler and angiography (kappa = 0.75). After mitral valve repair in 18 patients (15 ischemic MR, 3 cleft valves), color Doppler was used to assess severity of residual MR intraoperatively and postoperatively. Intraoperative color Doppler identified satisfactory repair (MR less than or equal to 2+) in 15 patients and failure (MR greater than or equal to 3+) in 3, whereas conventional surgical assessment of MR by fluid filling of the arrested ventricle failed to provide reliable differentiation. MR severity on subsequent closed-chest color Doppler follow-up did not change significantly compared with intraoperative evaluation after repair. Intraoperative color Doppler provides accurate grading of MR severity, offers instantaneous evaluation of the adequacy of mitral valve repair before chest closure, and appears to predict the degree of postoperative MR seen on subsequent closed-chest follow-up studies.

Blood Flow Velocity↗
PubMed1987

Experimental evaluation of technetium-99m red blood cell radionuclide ventriculography for detecting pericardial bleeding.

Abnormal loculated or diffuse blood pools adjacent to the heart have been observed in patients with pericardial bleeding who have been imaged by gated equilibrium radionuclide ventriculography (RNV). To study the scintigraphic appearance of fresh pericardial blood, we performed equilibrium RNV in six dogs with measured volumes (10, 30, or 50 ml) of intrapericardial blood. Loculated and diffuse pericardial blood was simulated by injecting the blood either into an intrapericardial balloon, or freely into the pericardial space. Ability to detect pericardial blood was determined by blinded review, and blood volume analysis was attempted by measuring its scintigraphic thickness, brightness (relative to the left ventricle), extent, and background-subtracted count rate and a peak count index. Detection rates for 10, 30, and 50 ml were all 100% for loculated pericardial blood, and 67%, 100% and 100% for free pericardial blood, with the use of three scintigraphic views. Visually determined "extent" of the abnormal blood pool was the most reliable indicator of pericardial blood volume. When the volume was 30 ml or more, at least 40% of the heart was surrounded in 26 of 27 cases (96%); the specificity of this finding was 90%. We conclude from this animal study that RNV should be a sensitive method for detecting pericardial bleeding; visual appearance permits qualitative assessment of the volume of accumulated labeled blood.

Animals↗
PubMed1987

Life-threatening postoperative pulmonary complications in patients with previous amiodarone pulmonary toxicity undergoing cardiothoracic operations.

Amiodarone therapy for cardiac arrhythmias is increasingly being recognized to be associated with pulmonary toxicity. In this report, we describe the case histories of four patients with previously diagnosed amiodarone pulmonary toxicity in whom the adult respiratory distress syndrome developed after cardiothoracic operations for malignant ventricular arrhythmias. Three patients underwent endocardial resection (two died), and a fourth patient had implantation of an automatic defibrillator unit. Radiographic changes and results of pulmonary function testing are evaluated during initial toxicity and preoperatively. These four patients (mean amiodarone dosage of 420 mg/day for 20 months) are compared to 13 other patients undergoing cardiothoracic operations with prior amiodarone treatment (one patient with preoperative pulmonary toxicity) in whom life-threatening postoperative pulmonary complications did not develop (mean dosage of 550 mg/day for 10 months). Mean preoperative serum amiodarone levels for the four patients were 1.5 micrograms/ml. In the two patients who died, desethylamiodarone levels were 510 and 4,400 micrograms/gm in pulmonary tissue. Histologic examination showed "honeycomb" appearance of the lung with prominent septae, alveolar foamy macrophages, and hyperplasia of alveolar lining cells, consistent with amiodarone pulmonary toxicity. Causes including pump-oxygenator time, oxygen toxicity, anesthetic agents, congestive heart failure, and pulmonary infection superimposed on amiodarone pulmonary toxicity are discussed with a review of the literature.

Aged↗
PubMed1987

Intraoperative evaluation of mitral regurgitation by Doppler color flow mapping.

Excessive residual mitral regurgitation after mitral valve reconstruction or coronary artery bypass graft surgery may necessitate reoperation. We evaluated a new intraoperative technique for assessment of mitral regurgitation, real-time two-dimensional Doppler color flow mapping, in 96 patients undergoing cardiac surgery. In comparison with technically adequate preoperative left ventriculography (n = 68) obtained at a similar level of afterload (systolic arterial pressure), Doppler color flow mapping demonstrated a sensitivity of 94% (50/53) and specificity of 93% (14/15) for detection of the presence and absence of mitral regurgitation, respectively. Semiquantitative comparison of color Doppler with angiography demonstrated excellent agreement (kappa = .80, p less than .001), differing by more than one grade in two patients (3%). The pulmonary capillary wedge "V" wave pressure (absolute magnitude, and height above mean) correlated poorly with the simultaneously obtained mitral regurgitation grade by color Doppler, both before (r = .37 and .45) and after (r = .04 and -.15, p = NS) cardiopulmonary bypass. No value of the V wave clearly distinguished 3 + or 4 + regurgitation from lesser degrees of regurgitation. In 15 patients who underwent mitral valve repair, fluid filling of the ventricle was falsely positive (leak, with no regurgitation) in 40% (2/5), and falsely negative (no leak, with 2 + to 3 + regurgitation) in 30% (3/10). Regurgitation grade by color Doppler demonstrated a highly significant (p less than .01) dependence on systolic pressure, suggesting that intraoperative changes in afterload conditions importantly influence mitral regurgitation severity. Thus, Doppler color flow mapping provides accurate intraoperative evaluation of mitral regurgitation and may aid surgical decision making.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Vessel Prosthesis↗
PubMed1986

Combined valve and coronary artery bypass procedures in septuagenarians and octogenarians: results in 120 patients.

A consecutive series of 96 septuagenarians (mean age, 74) and 24 octogenarians (mean age, 83) underwent coronary artery bypass (CAB) and valve operations using hypothermia and hyperkalemic cardioplegia in a 45-month period; there was a mean of 2.6 grafts per patient. Most patients were in New York Heart Association (NYHA) class IV (57% of the septuagenarians and 88% of the octogenarians) preoperatively. The early deaths were 19% for septuagenarians and 37% for octogenarians; late deaths were 9% and 6%, respectively, after a mean of 25 months. Of 92 survivors, 78% of the septuagenarians and 87% of the octogenarians improved by one or more NYHA class postoperatively. Of 58 patients with combined CAB and aortic valve replacement, 12 (21%) died; of 38 with combined CAB and mitral valve replacement 19 (50%) died; 2 of 9 (22%) with combined CAB and double valve replacement died; and 2 of 11 (18%) with CAB and MV repair died. In comparison, of patients with isolated valve replacement in the same period, 2 of 30 (7%) in the AVR group died, 5 of 17 (29%) died in the MVR group, 2 of 7 (33%) in the DVR group died. The risk of combined valve procedures and bypass surgery was significantly increased in the elderly and may warrant a less aggressive procedure, especially in the mitral position.

Aged↗
PubMed1986

Cardiac surgery in the octogenarian.

Seventy-six consecutive patients, aged 80 to 89 (mean 82), underwent cardiac operations with cardiopulmonary bypass. Hypothermia (22 degrees C) and hyperkalemic cardioplegia were used in each. There were 35 men and 41 women. Thirteen patients (17%) were in New York Heart Association Functional Class III and 62 patients (81%) were in Class IV preoperatively. Coronary bypass procedures (Group I) were performed in 38 patients, of whom five had combined carotid endarterectomy. The average number of grafts was 3.7 per patient. There were two early deaths (5.2%). Single or double valve replacement, without coronary bypass (Group II), was done in 15 patients, with one early death (6.6%). Coronary bypass and valve procedures (Group III) were performed in 23 patients with seven early deaths (30%). Total early mortality was 10 deaths in 76 patients (13%). Of the 66 (87%) 30 day survivors, 19 (29.1%) had major postoperative complications, including bleeding, pericardial tamponade, sternal dehiscence, myocardial infarction, arrhythmia, and pump failure. Mean hospital stay was 23 days (9 to 117 days). Late cardiac-related deaths occurred in eight patients (9%) during the 58 (mean 28) months of follow-up. Thus combined early and late mortality was 18 deaths (24%). Mortality at any time was related to Functional Class IV status (17/18 deaths, 94% in Class IV); combined procedures (12/28 patients died, 43%); use of intra-aortic balloon pumping (8/13 patients died, 62%); and postoperative bleeding necessitating reoperation (4/6 patients died, 67%). At follow-up 84% of survivors had improved by one or more functional classes, and there was a low incidence of cardiac-related late deaths. This experience supports the concept that in octogenarians the indications for operation should be as for other patients of less advanced age, especially in those with isolated coronary artery disease and pure valve disease. Operation should not be delayed, so that these patients will not advance to higher-risk Class IV status preoperatively.

Age Factors↗
PubMed1986

Intraoperative coronary angioscopy. Technique and results in the initial 58 patients.

Coronary angioscopy provides images of intravascular detail with greater than 0.2 mm spatial resolution and excellent contrast resolution. Using endoscopes of 1.25 to 1.8 mm outer diameter, we performed intraoperative angioscopy of the coronary arteries or saphenous vein grafts, or both, in 58 patients. Eighty-one native coronary arteries and 43 vein grafts were examined. A clear viewing field was created by infusion of crystalloid cardioplegic solution through the aortic root during cardiopulmonary bypass. Technical details crucial for obtaining high-quality images were as follows: sufficient coronary perfusion by cardioplegic solution to displace all blood; adequate intraluminal illumination; and high-quality fiberoptic and lens systems. Incomplete studies in approximately 14% of patients were related to failure to achieve these technical details and lack of scope steerability. In 30% of patients, previously unrecognized anatomic details were revealed by angioscopy. These included intimal flaps at the site of vein-to-artery anastomoses, atheromatous plaques with adherent thrombi, and hemorrhagic ulcerated plaques, not recognized on angiography. Although a coronary intimal flap developed proximal to the anastomosis during retrograde examination in two patients, no serious complications occurred as a result of the procedure. We conclude that intraoperative angioscopy is safe, provides novel information that may be clinically relevant, and has future potential for development of the techniques for coronary endarterectomy and intraoperative balloon and laser angioplasty.

Angina, Unstable↗
PubMed1985

Free-floating ball thrombus in the left atrium after mitral valve replacement: successful surgical management.

A free-floating ball thrombus in the left atrium is a rare clinical problem with potentially catastrophic consequences. Thus, early diagnosis and prompt surgical intervention are mandatory. Free ball-valve thrombus within the left atrium developed in a patient who had undergone mitral valve replacement with a Starr-Edwards prosthesis seven years previously. The diagnosis was accurately made by two-dimensional echocardiography and was followed by successful removal of a thrombus. A review of the literature is presented.

Echocardiography↗
PubMed1985

Fascicular conduction disturbances and ischemic heart disease: adverse prognosis despite coronary revascularization.

In patients with ischemic heart disease, fascicular conduction disturbances are associated with increased mortality. This study reveals that increased mortality also exists for certain types of fascicular conduction disturbances after myocardial revascularization. In 227 consecutive patients undergoing bypass surgery, 24 had preoperative and an additional 52 developed at surgery a fascicular conduction disturbance. At 66 +/- 14 months of follow-up, 6 (4%) of 148 control patients without pre- or postoperative fascicular conduction disturbances had died from cardiac causes. Although right bundle branch block and left hemifascicular block were the most common form of fascicular conduction disturbance, only 1 of 55 of these patients died (p = NS). Mortality rates were much higher for patients with left bundle branch block or an intraventricular conduction defect; 8 (38%) of 21 died from cardiac causes (p less than 0.05). A high risk subgroup was identified by comparing 14 consecutive patients with left bundle branch block or an intraventricular conduction defect who survived more than 1 year postoperatively with 21 consecutive patients with these same conduction defects who died within 1 year of surgery. The following variables were significantly (p less than 0.05) different (survivors versus nonsurvivors): age (58 +/- 7 versus 65 +/- 9 years); class IV angina (2 of 14 versus 16 of 21), prior myocardial infarction (9 of 14 versus 21 of 21), left ventricular ejection fraction (53 +/- 18 versus 41 +/- 15%), three vessel disease (9 of 14 versus 20 of 21) and left ventricular aneurysm (2 of 14 versus 13 of 21).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗