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Biomedical subjects

H R Kay

Publications and source records attributed to H R Kay.

34 records · Page 2Linked to original sources
PubMed1985

Electrophysiologic testing in patients at high risk for sudden cardiac death. I. Nonsustained ventricular tachycardia and abnormal ventricular function.

Nonsustained ventricular tachycardia, although usually asymptomatic, is associated with a high risk of sudden cardiac death in patients with depressed left ventricular function. To test the vulnerability of such patients to symptomatic and potentially life-threatening arrhythmias, complete electrophysiologic studies were performed in 58 patients with clinically documented nonsustained ventricular tachycardia (greater than or equal to three complexes but less than 15 seconds of self-terminating ventricular tachycardia by 24 hour ambulatory electrocardiographic [Holter] or telemetric monitoring) and abnormal left ventricular function (ejection fraction less than 50% by radionuclide angiography). All patients had nonsustained ventricular tachycardia in the absence of antiarrhythmic drugs, acute ischemia, long QT syndrome, recent infarction or electrolyte abnormalities. The stimulation protocol for each patient included the introduction of single, double and triple ventricular extrastimuli at three cycle lengths (sinus, 600 and 450 ms) and two right ventricular sites (apex and outflow tract). A sustained ventricular tachyarrhythmia was induced in 23 patients (40%) and a nonsustained ventricular tachycardia in 14 patients (24%). Induction of sustained tachycardia correlated with the presence of akinesia or aneurysm, or both, by radionuclide angiography, but not with ejection fraction or presence or absence of coronary artery disease. These results indicate that: 1) patients with clinical nonsustained ventricular tachycardia and chronic left ventricular dysfunction have a high incidence of inducible sustained ventricular tachycardia or ventricular fibrillation; and 2) electrophysiologic testing may allow further substratification of risk of sudden cardiac death in high risk patients with nonsustained ventricular tachycardia.

Adult↗
PubMed1984

Noncardiogenic pulmonary edema after cardiopulmonary bypass. An anaphylactic reaction to fresh frozen plasma.

Nine episodes of fulminant noncardiogenic pulmonary edema after cardiopulmonary bypass were observed in eight patients between September 1977 and December 1982. All these catastrophic reactions occurred during administration of fresh frozen plasma 30 minutes to 6 hours after discontinuation of cardiopulmonary bypass. In one patient, two episodes of noncardiogenic pulmonary edema occurred 4 hours apart. In each instance, fresh frozen plasma was being administered. In all patients, pulmonary artery diastolic pressure became elevated during the administration of fresh frozen plasma while left atrial pressure or pulmonary capillary wedge pressure progressively decreased, and cardiac output deteriorated markedly in all but one patient. Corticosteroids, positive end-expiratory pressure, and catecholamines were administered to all patients. All deaths were due to a decrease in cardiac output. Cardiac output did not increase substantially with the use of an intraaortic balloon pump or the administration of catecholamines. The last two patients in the series showed a steady and remarkable improvement in cardiac output when the wedge pressure was increased to a level above 15 mm Hg with the administration of normal saline solution. Our data suggest the following: (1) noncardiogenic pulmonary edema after cardiopulmonary bypass is most probably an anaphylactic reaction to fresh frozen plasma. (2) The syndrome is reversible within hours; in only one patient (who suffered noncardiogenic pulmonary edema twice) did adult respiratory distress syndrome develop. (3) The three deaths were not related to hypoxia but to the deleterious effects of low cardiac output associated with hypovolemia secondary to fluid loss through the lungs and possibly across other capillary beds. Therefore, treatment should include restoration of adequate left-sided filling pressures to achieve satisfactory cardiac output.

Adolescent↗
PubMed1983

Ventricular arrhythmias: use of electrophysiologic studies.

The clinical utility of electrophysiologic testing in assessing the long-term efficacy of amiodarone for treatment of life-threatening ventricular arrhythmias is controversial, most investigators reporting little or no correlation between the early effects of the drug on arrhythmia inducibility and subsequent prognosis. We have evaluated 69 consecutive patients given amiodarone for ventricular tachycardia (VT) or fibrillation (VF). All patients underwent provocative electrophysiologic testing with programmed electrical stimulation before and after amiodarone loading. After a standardized amiodarone loading regimen, the patients' arrhythmias were not inducible in 22 patients (group 1) and remained inducible in 47 patients (group 2). No patient in group 1 has had a recurrence of VT/VF, whereas 15 (32%) of 47 patients in group 2 have had recurrences. The characteristics of the arrhythmia induced by programmed stimulation in group 2 accurately predicted the severity of the recurrence. We conclude that electrophysiologic testing may be useful in evaluating the efficacy of amiodarone for the long-term treatment of VT/VF and that its precise role in this context should be further investigated by stringently controlled studies.

Adult↗
PubMed1983

Measurement of ejection fraction by thermal dilution techniques.

The reproducibility, accuracy, and clinical applicability of ventricular ejection fraction derived by a thermal dilution technique were assessed in 22 dogs and 18 patients. Results obtained by the thermal technique were compared to simultaneous results obtained by radionuclide angiography. Right ventricular ejection fraction, measured in 9 dogs (1014 determinations) and 8 patients (744 determinations) was reproducible +/- 5%. Left ventricular ejection fraction, measured in 10 patients, was reproducible +/- 5%. Correlation between thermal and radionuclear measurements varied from 0.86 to 0.93 (all P less than 0.02). We conclude that, because of its low cost, ease of use, and accuracy, thermally derived ejection fraction determinations can be helpful in hemodynamic monitoring of critically ill patients.

Angiography↗
PubMed1983

Use of computed tomography to assess mediastinal complications after median sternotomy.

Thirty computed tomographic (CT) scans from 27 patients who had undergone median sternotomy were reviewed. A control group of 15 asymptomatic patients was studied either early (within 21 days) or late (46 days to 22 years) after sternotomy. Twelve patients with symptoms ranging from sternal click to obvious mediastinitis also were studied within 30 days of sternotomy. The CT findings were correlated with the patient's clinical course. Imperfect sternal closure (sternal step-offs and gaps) was found in 10 of the 15 asymptomatic patients. Focal retrosternal fluid collections, air, and hematomas were seen in more than 75% of the asymptomatic patients. Retrosternal abscess, presternal abscess, and sternal disruption were noted in 3 symptomatic patients. Computed tomography correctly diagnosed the extent of mediastinal abscess in all patients. In the 3 patients in whom there was a discrepancy between the CT scan and the clinical findings, the scan ultimately was shown to be correct. These results indicate that computed tomography is a valuable tool in diagnosing wound problems after sternotomy because it accurately depicts the extent and depth of the wound infection.

Adult↗
PubMed1983

Complications of median sternotomy: computed tomographic evaluation.

Complications of median sternotomy are infrequent (0.5%-5%) but have a very high mortality and morbidity. Conventional radiographic techniques are of limited value in assessing these complications. Twenty sternotomy patients without problems and 12 with clinical problems were studied with CT. In the control group, focal edema, focal hematomas, and minor sternal irregularities were universal. In the problem group, CT was able to distinguish the six patients without significant infection from the six with major infections. In the latter group, CT was of great value in determining whether the infection was limited to the presternal tissues, the anterior mediastinum, or both.

Abscess↗
PubMed1981

Correlation of patterns of subendocardial reperfusion and left ventricular performance after ischemia.

Ninety-three dogs were studied with normothermic or hypothermic ischemia for 60 or 90 minutes, with or without potassium cardioplegia. Radioactive-labeled microspheres (9 +/- 1) were injected into the aortic perfusion cannula just prior to aortic cross-clamping and at 2, 6, and 10 minutes after the clamp was released. Left ventricular (LV) function was analyzed with a right heart bypass model before and 45 minutes after the ischemia period. Changes in LV function were defined as the arithmetic difference in the center of mass between preischemia and postischemia computer-drawn Sarnoff curves. Regardless of technique of myocardial protection, increased subendocardial flow 2 minutes after ischemia correlated strongly with preservation of LV function (p less than 0.01). Well-preserved hearts showed a rapid return to normal levels of coronary blood flow (p less than 0.01). In contrast, a delay in the peaking of subendocardial flow to 10 minutes was associated with poor function (p less than 0.01). There was a high correlation between ultrastructural morphology and LV function. While well-preserved hearts showed early preferential subendocardial perfusion, the poorly protected myocardium is unable to restore adequate subendocardial flow early in the reperfusion period.

Animals↗
PubMed1978

Clinical experience with intraaortic balloon pump support in 728 patients.

From November, 1968, through December, 1976, intraaortic balloon pump (IABP) circulatory support was used 747 times in 728 patients. Overall in-hospital survival was 413/747 (56.9%). Survival with IABP since 1974 has been 65% (286/440) compared to 24% (18/75) in 1968-1971 (P < 0.001). Two practical changes have been associated with this improvement: 1) broadened indications for, and earlier insertion of, IABP; and 2) more aggressive surgical treatment of the primary cardiac lesion. Cardiogenic shock or chronic ischemic ventricular failure accounted for 78.7% (59/75) of IABP in 1968-1971; during 1974-1976 only 26.4% (116/440) of IABP-supported patients were in these categories (P < 0.001). Since 1974, 58.2% (153/263) of IABP patients had an operative procedure following IABP insertion compared to 37.7% (23/611 prior to 1971 (P < 0.01). The major complication rate has remained unchanged at 8.5%. IABP-related mortality rate was 0.8% (6/728). Earlier, more liberal, use of IABP hemodynamic support has led to increased survival in a large number of patients with complications of acute myocardial ischemia. The low mortality associated with its use vindicates earlier institution of IABP support in cardiogenic shock.

Equipment Failure↗
PubMed1978

Effect of cross-clamp time, temperature, and cardioplegic agents on myocardial function after induced arrest.

To evaluate the importance of time, temperature, and cardioplegia on the ability of the canine myocardium to maintain functional and ultrastructural integrity following induced arrest, we studied 220 dogs by varying myocardial temperature (34 degrees, 24 degrees, and 11 degrees C.), arrest time (0 to 120 minutes), and cardioplegic agents. Change in left ventricular function (LVF) was defined as the arithmetic difference in the center of mass between prearrest and postarrest LVF curves and was expressed as percent recovery of left ventricular stroke work. Left ventricular biopsies were obtained for semiquantitative electron microscopic analysis. After 90 minutes of cross-clamping, only hearts protected with combined hypothermia (H) and potassium-induced cardioplegia (K) significantly recovered prearrest function (24 degrees C.--80 percent, 11 degrees C.--99 percent). Hypothermia (H) alone for 90 minutes was less protective (24 degrees C.--49 percent, 11 degrees C.--59 percent). H preserved 84 percent of function after 60 minutes and 91 percent after 45 minutes. Normothermic arrest resulted in only 39 percent return of function at 45 minutes but could be extended with potassium-induced cardioplegia(K) to 78 percent at 60 minutes and 54 percent at 90 minutes. The addition of procaine plus HK improved protection over HK alone (95 percent versus 80 percent) but by itself was not effective. Neither hydrocortisone nor pretreatment with glucose-insulin-potassium, branched chain amino acids, or propranolol increased the protective effect of HK plus procaine. Inadequately protected groups (normothermia or H without K) showed more myocytic and capillary endothelial damage than the HK groups. No technique of myocardial protection studied completely preserved LVF, but the combination of HK plus procaine resulted in maximal recovery of LVF following cross-clamping for up to 120 minutes.

Animals↗
PubMed1976

Atherosclerosis of the internal mammary artery.

To better evaluate the incidence of atherosclerosis in the internal mammary artery (IMA), 215 IMA segments from routine postmortem examinations were evaluated microscopically. Significant atherosclerotic narrowing was seen in 9 patients (4.2%). No patient had more than a 50% reduction in lumen diameter. The degree of incipient atherosclerosis correlated well with age, hypertension, diabetes, and peripheral vascular disease.

Adult↗