Biomedical subjects

Mikhail Vaynblat

Publications and source records attributed to Mikhail Vaynblat.

5 recordsLinked to original sources

PubMed2006

Telemetric recording of intrapleural pressure.

BACKGROUND: Monitoring of intrapleural pressure (IPP) is used for evaluation of lung function in a number of pathophysiological conditions. We describe a telemetric method of non-invasive monitoring of the IPP in conscious animals intermittently or continuously for a prolonged period of time. MATERIALS AND METHODS: After IACUC approval, six mongrel dogs were used for the study. After sedation, each dog was intubated and anesthetized using 0.5% Isoflurane. A telemetric implant model TL11M2-D70-PCT from Data Science International was secured subcutaneously. The pressure sensor tip of the catheter from the implant was inserted into the pleural space, and the catheter was secured with sutures. The IPP signals were recorded at a sampling rate of 100 points/second for 30 to 60 min daily for 4 days. From these recordings, the total mean negative IPP (mmHg), and the total mean negative IPP for a standard time of 30 min were calculated. In addition, the actual inspiratory and expiratory pressures were also measured from stable recording of the IPP waveforms. RESULTS: In six dogs, the total mean +/- SD negative IPP was -10.8 +/- 10.6 mmHg. After normalizing with respect to acquisition time it was -13.2 +/- 11.2 mmHg/min. The actual inspiratory pressure was -19.7 +/- 15.3, and the expiratory pressure was -11.0 +/- 12.9. CONCLUSIONS: Our study demonstrates that telemetric monitoring of IPP can be performed reliably and non-invasively in conscious experimental animals. The values for IPP in our study are compatible with the results of other investigators who used different methods of IPP measurement. Further work may show this method to be helpful in understanding the pathophysiology of various breathing disorders.

Animals↗

PubMed2003

Telemetrically monitored arrhythmogenic effects of doxorubicin in a dog model of heart failure.

A model of chronic heart failure has been induced in dogs by repeated intracoronary infusion of doxorubicin, which is an antineoplastic medication that has dose-limiting cardiotoxic side effects. Although many of the dogs receiving doxorubicin develop typical signs of dilated cardiomypathy over 4-6 weeks, some of them suddenly die before completing the four weekly infusions of the drug. The present study was undertaken to determine whether such sudden death may be caused by the development of fatal arrhythmias during doxorubicin treatment. This was assessed by telemetrically monitoring the EKG of seven dogs, which received intracoronary infusion of 1 mg/kg doxorubicin given in four divided weekly doses. The recordings were obtained for 8-10 h on alternate days up to 4 weeks. Echo-cardiographic recordings were obtained once a week. The acute effects with each infusion of doxorubicin included a significant increase in heart rate, and no significant change in QRS complex. The cumulative prolonged effects of doxorubicin included slight reduction in QRS amplitude and duration, and marked arrhythmic changes. Four out of seven dogs showed a spectrum of arrhythmic events such as single or groups of premature ventricular complexes (PVCs), bigeminy, ventricular tachycardia (VTAC), ventricular fibrillations (VFIB), and asystole. All dogs did not show each of the events listed above and the same dog did not show all the events all the time. One of these four dogs developed VFIB for 25 min and then asystole leading to sudden death. These studies conclusively showed that fatal arrhythmias develop in some of the dogs receiving doxorubicin treatment accounting for the sporadic incidence of sudden death. Prophylactic treatment with antiarrhythmic agents may prevent such adverse events.

Journal Article↗

PubMed2002

Simultaneous angiotensin converting enzyme inhibition moderates ventricular dysfunction caused by doxorubicin.

AIMS: The purpose of this study was to determine that the administration of an angiotensin converting enzyme (ACE) inhibitor enalapril would confer protection against doxorubicin-induced experimental heart failure, and attenuate the development of left ventricular dysfunction. METHODS: Seventeen dogs were chronically instrumented with an intracoronary catheter and received doxorubicin weekly for 4 weeks. Animals were assigned to two groups: group 1: untreated heart failure; and group 2: simultaneous enalapril administration (5 mg twice a week). Hemodynamic data were obtained at week 0 and 12. Echocardiography was performed weekly. RESULTS: Survival improved with simultaneous enalapril administration (36% in group 1 vs. 100% in group 2, P=0.04). The increase in the left ventricular end-diastolic pressure was significantly reduced at week 12 (17+/-1 mmHg in group 1 vs. 9+/-1 mmHg in group 2, P=0.0042). The fall in left ventricular stroke work index was significantly prevented (52% in group 1 vs. 21% in group 2, P=0.006). The increase in right ventricular end-diastolic diameter was significantly reduced by enalapril prophylaxis. CONCLUSION: Simultaneous treatment with enalapril was beneficial in the prevention of doxorubicin-induced cardiomyopathy.

Angiotensin-Converting Enzyme Inhibitors↗

PubMedDate not supplied

Relationship between upper airway obstruction and gastroesophageal reflux in a dog model.

The association between gastroesophageal reflux (GER) and upper airway obstruction in children is recognized but not well understood. Our objective was to determine if the creation of a model of upper airway obstruction in dogs would cause GER and to determine if the GER is related to intrathoracic pressure changes. Five dogs underwent evaluation with esophageal manometry and pH probe at baseline and 1 week after creation of an upper airway obstruction. Airway obstruction was created by placement of a fenestrated cuffed tracheostomy tube, which was then capped and the cuff was inflated, requiring the animals to breathe via the fenestrations. The negative inspiratory pressure (Pes) (+/- SD) increased from 11.8 +/- 4.8 cm H(2)O at baseline to 17.6 +/- 4.9 cm H(2)O 1 week after creation of an airway obstruction (p = .029). None of the dogs had GER at baseline with a reflux index (RI) value of 0.0; however, 1 week after creation of airway obstruction, three out of five dogs had GER, with a mean RI value of 21.2 +/- 21.2. There was a significant (p = .023) correlation (r = .928) of the changes in Pes and RI values following airway obstruction. Upper airway obstruction (UAO) does cause GER in this canine model. Severity of GER is significantly correlated with Pes changes.

Airway Obstruction↗

PubMedDate not supplied

Open heart surgery in patients 85 years and older.

BACKGROUND: There has been an increase in the number of elderly patients considered for cardiac surgery. Several reports have documented acceptable morbidity and mortality in patients 80 years and older. The results from surgical patients 85 years and older were analyzed. METHODS: The records of 89 consecutive patients 85 years and older having cardiac operations between June 1993 and May 1999 were retrospectively reviewed. For purposes of statistical analysis follow-up was considered as a minimum of one office visit to the surgeon, cardiologist, or internist at least 1 month postoperatively. RESULTS: Eighty-seven patients underwent coronary artery grafting and two patients had mitral valve replacement. Follow-up was 100% complete. The operative mortality rate was 12.3%; probability of in-hospital death was 8.2%; risk-adjusted mortality rate was 3.2%. The complication rate was 31.5%. The actuarial 1-, 3-, and 5-year survivals were as follows: 75%, 67%, and 40%. Multivariate predictors of 30-day mortality were preoperative EF, less than 30% (p = 0.029) and postoperative renal failure (p = 0.0039). CONCLUSIONS: Cardiac surgery can be performed in patients 85 years and older with good results. There is an associated prolonged hospital stay for elderly patients. Consistent successful outcomes can be expected in this patient population with selective criteria identifying risk factors.

Adult↗