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J K Kirklin

Publications and source records attributed to J K Kirklin.

At least 91 records · Page 5Linked to original sources
PubMed1992

Can the heart be chronically paced with electrodes on the pericardial surface?

During implantable defibrillator (ICD) operations, we measured acute and chronic transpericardial bipolar pacing thresholds through standard myocardial surface electrodes sewn on the pericardium for chronic ICD QRS rate-sensing use. We compared observations in 24 patients on day 0 with chronic measurements in seven patients at 27.4 +/- 12.1 (median 31.7) months. The leads were used only for QRS rate-sensing, not for pacing, during the time between acute and chronic measurements. Acute transpericardial pacing threshold at 0.5-msec stimulus duration on day 0 was 4.5 +/- 2.19 V (standard deviation), median 3.5 V, and at median time 964 days postimplantation was 3.8 +/- 2.07 V, median 3.5 V. Mean acute pacing current threshold was 3.7 +/- 1.90 mA, n = 23, and chronic was 2.7 +/- 1.79 mA, n = 6. Acute bipolar impedance was 1,209 +/- 383 ohms, median 1,138 ohms, and chronic was 1,550 +/- 358 ohms, median 1,410 ohms, n = 7. Acute bipolar QRS amplitude was 12.3 +/- 5.93 mV, median 12.1 mV, n = 24, and chronic was 13.5 +/- 8.5 mV, median 17.2 mV, n = 7. None of the changes between the acute and chronic states was statistically significant, with the exception of bipolar impedance (P = 0.054). We concluded that: (1) transpericardial pacing threshold did not increase with time; (2) initial and chronic pacing impedances were high and current low; (3) QRS amplitudes were highly satisfactory for defibrillator rate-sensing; and (4) this approach to ICD implantation left the surgically virgin heart unscarred to make future transplantation easier, and enhanced safety when previous cardiac operations had been done.

Cardiac Pacing, Artificial↗
PubMed1992

Application of echocardiographic color flow Doppler mitral regurgitation to the diagnosis of acute cardiac transplantation rejection.

Numerous noninvasive techniques have been examined for the detection of acute rejection following cardiac transplantation, but none has proven sufficiently sensitive to replace the endomyocardial biopsy. A prospective study was performed in 92 heart transplant patients in order to test the hypothesis that mitral regurgitant ratio by two-dimensional echocardiography with Doppler flow mapping could detect moderate or severe acute allograft rejection. There were 82 rejection episodes identified, of which 40% were associated with mitral regurgitation by echo-Doppler at the beginning of the episode. With augmentation of immunosuppression during a rejection episode, there was a progressive fall in the degree of mitral incompetence (P = 0.03). The sensitivity of color Doppler studies in identifying rejection was low (60% of all rejection episodes had no associated mitral incompetence at the beginning of the episode), but the likelihood of rejection progressively increased with higher degrees of mitral regurgitation (P less than 0.01), approaching 60% when the echo-Doppler regurgitant ratio exceeded 15%. Echo-Doppler studies do not provide sufficient sensitivity to be useful as a screening technique for acute cardiac rejection, but high or increasing echocardiographic mitral regurgitant ratio is predictive of acute rejection and should indicate prompt endomyocardial biopsy.

Adolescent↗
PubMed1992

Quantitation of mapping uncertainty in Wolff-Parkinson-White syndrome. Implications for anatomic characterization and surgical division of accessory atrioventricular connections.

The purpose of this study was to quantitate the uncertainty inherent in the electrophysiologic mapping of ventricular preexcitation as seen in Wolff-Parkinson-White syndrome. An ink-coated needle electrode was constructed to serve as a point source of unipolar stimulation along the atrioventricular junction. Activation times for 11 ventricular mapping sites at the atrioventricular junction were measured for each stimulation point. Maps were successfully completed for 18 right free wall and 14 posterior septal stimulation points. The activation time at the mapping site closest to the stimulation point was termed the index activation time. Activation times identical to the index activation time were noted at 1.3 +/- 0.5 mapping sites for each free wall stimulation point and 1.9 +/- 0.9 mapping sites for each septal stimulation point (p < 0.05, septal versus free wall stimulation points). Activation times falling within 5 msec of the index activation time were noted at 2.4 +/- 1.0 mapping sites for each free wall stimulation point and at 3.9 +/- 1.4 mapping sites for each septal stimulation point (p < 0.05, septal versus free wall stimulation points). The uncertainty of electrophysiologic mapping can be quantitated, and this error should be considered when making inferences regarding the anatomy of accessory pathways based on electrophysiologic data. A knowledge of the uncertainty inherent in the localization of accessory atrioventricular connections by electrophysiologic mapping can be used to plan borders of surgical dissection that will account for this uncertainty at a 95% confidence level.

Animals↗
PubMed1992

Rejection after cardiac transplantation. A time-related risk factor analysis.

BACKGROUND: The determinants of early and repeated episodes of acute rejection after cardiac transplantation remain elusive. METHODS AND RESULTS: To gain insight into this phenomenon, a multivariate analysis for repeated events was applied to 229 patients receiving 249 transplanted hearts between 1981 and July 1, 1991 (595 rejection episodes). The mean frequency of rejection per patient after initial cardiac transplantation was 1.2 at 3 months, 1.8 at 1 year, and 2.8 at 5 years. The pattern of rejection was characterized by an early period of higher risk (greatest during the first month) followed by a low constant risk that continued throughout the period of follow-up (maximum, 9.5 years). By multivariate analysis, risk factors were identified for the likelihood of subsequent rejection after a previous rejection episode (or time of transplantation). Triple-drug immunosuppression plus induction therapy yielded a higher risk of early subsequent rejection compared with other baseline immunotherapy protocols, but it also provided the greatest freedom (95%) from rejection-related death during the first year. Risk factors in the constant phase of hazard included younger age at transplant, female donor and/or recipient, longer donor ischemic time, greater HLA donor-recipient mismatch, and an increased number of previous rejection episodes. CONCLUSIONS: Immunologic and other patient-specific characteristics as well as rejection history predict the likelihood of future rejection events. The value of any antirejection protocol must be evaluated both in terms of rejection episodes and rejection-related deaths. Future analyses may identify specific high- and low-risk patient subsets for rejection, which may provide a more rational basis for altering the amount of chronic immunosuppressive therapy.

Adult↗
PubMed1992

Wolff-Parkinson-White syndrome. A quantitative morphometric analysis of surgical anatomy.

Previous descriptions of the four anatomic regions of dissection in Wolff-Parkinson-White syndrome have been largely qualitative. In this study quantitative data describing this anatomy are presented, together with statistical analysis of selected anatomic relationships. Fourteen human hearts were dissected. The borders of the posteroseptal dissection along the mitral anulus, tricuspid anulus, and epicardium were measured. A positive correlation between the mitral and tricuspid annular dimensions was found (r = 0.55; p = 0.04); however, the length of epicardial dissection was more variable. The dimensions of the anteroseptal space and the position of the right coronary artery within this space were measured. These measurements emphasize the proximity of the aortic sinuses of Valsalva to the right atrial endocardium near the posteromedial extent of the dissection. The dimensions of the right and left free walls and the position of the coronary arteries within these spaces were measured. A positive correlation was found between the width of the atrioventricular groove and the length of the dissection necessary to separate the atrioventricular groove fat from the ventricular surface (r = 0.89; p = 0.0001, right free wall; r = 0.87; p = 0.0001, left free wall). The quantitative data presented in this article are intended to enhance the surgeon's appreciation of the anatomy relevant to the treatment of Wolff-Parkinson-White syndrome. The knowledge gained from this quantitative analysis may improve accuracy in the electrophysiologic localization and surgical disruption of accessory atrioventricular connections.

Autopsy↗
PubMed1992

Morphologic and surgical determinants of outcome events after repair of tetralogy of Fallot and pulmonary stenosis. A two-institution study.

Survival after entry and survival after repair (94%, 91%, and 91% at 1 month, 1 year, and 5 years, respectively) were similar in two institutions treating 196 consecutive patients, and there was no advantage (and a possible disadvantage) of a protocol of preliminary shunting and later repair in very young patients. Size and configuration of the right and left pulmonary arteries had no demonstrable effect on survival, prevalence of transannular patching, or postrepair right ventricular-left ventricular pressure ratio. Small size of the pulmonary "anulus" and trunk were risk factors for death, transannular patching, and high postrepair pressure ratio. High postrepair pressure ratio was a risk factor for death after repair. Very young age (less than about 3 months) was a risk factor for death after repair, particularly when other risk factors coexisted. The prevalence of transannular patching in patients with mild infundibular and pulmonary anulus and trunk hypoplasia decreased across the time of the study, without ill effect. The usefulness of measuring postrepair right ventricular-left ventricular pressure ratio is emphasized by the data.

Female↗
PubMed1991

Intermediate septal accessory pathways: electrocardiographic characteristics, electrophysiologic observations and their surgical implications.

Intermediate septal accessory pathways are located in close proximity to the atrioventricular (AV) node and His bundle, have unique features that distinguish them from typical anterior and posterior accessory pathways and have been associated with a high risk for unsuccessful pathway division and the production of complete AV block after surgery. Between July 1986 and May 1990, 4 of 70 patients (3 men and 1 woman; mean age 33 +/- 13 years) undergoing surgery for accessory pathway division were found to have an intermediate septal accessory pathway. The presenting arrhythmia was atrial fibrillation with rapid anterograde conduction over the accessory pathway in two patients and recurrent orthodromic reciprocating tachycardia in two patients. In all patients, the delta wave on the electrocardiogram (ECG) was inverted in lead V1, but two patterns of delta wave configuration were observed. In three patients (type 1 intermediate septal accessory pathway), the delta wave was upright in lead II, inverted in lead III and isoelectric in lead a VF; the transition from a negative to an upright delta wave occurred in lead V2. The fourth patient exhibited a different delta wave pattern (type 2 intermediate septal accessory pathway). The delta wave was upright in each of leads II, III and aVF; the transition from a negative to an upright delta wave occurred at lead V3. Intraoperative electrophysiologic study localized the atrial insertion of type 1 pathways to the midpoint of Koch's triangle close to the AV node.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Endothelium-dependent responses in long-term human coronary artery bypass grafts.

In the present study, responses of long-term human coronary artery bypass grafts (CABGs) to known endothelium-dependent vasodilators, acetylcholine, calcium ionophore A23187, thrombin, and histamine, as well as authentic nitric oxide, the putative endothelium-derived relaxing factor, were studied. Sixteen CAGBs were isolated within 1-2 hours from hearts of 14 patients receiving a cardiac transplant. A total of 109 ring segments were prepared from these CABGs and studied in vitro. The duration of the CABGs ranged from 7 months to 12 years. Addition of acetylcholine (0.01-10 microM), calcium ionophore A23187 (0.01-1.0 microM), thrombin (0.01-1.0 unit/ml), and histamine (0.01-1.0 microM) consistently produced a dose- and endothelium-dependent relaxation, reaching a maximum of -35.3 +/- 3.3%, -45.3 +/- 5.5%, -26.9 +/- 4.8%, and -17.8 +/- 2.5% (mean +/- SEM), respectively. No significant difference was observed among the CABGs with different duration of transplantation, whereas the relaxant responses of different segments along the entire length of a CABG were markedly different. These latter differences in the endothelium-dependent responses appear to correlate inversely with the development of intimal proliferative lesions in these CABGs. Addition of nitric oxide (0.01-10 microM) produced a potent dose- and endothelium-independent relaxation, which was also slightly depressed in CABGs with severe intimal proliferation. These results demonstrate that long-term transplanted human saphenous vein grafts retain their endothelium-dependent responses and that development of severe intimal proliferative lesions, rather than the duration of the grafts, result in marked alterations in the reactivity of these transplanted CABGs.

Coronary Artery Bypass↗
PubMed1991

Usefulness of transesophageal echocardiography in assessment of aortic dissection.

BACKGROUND: The value of transesophageal echocardiography in the assessment of patients with aortic dissection was studied. METHODS AND RESULTS: Group 1 (34 patients) represented all patients studied at our institution with this technique in whom aortic dissection was proven by aortography, surgery, or autopsy. Group 2 (27 patients) represented all patients studied with this technique at our institution in whom aortic dissection was excluded by aortography. Transesophageal echocardiography made a correct diagnosis of aortic dissection in 33 of 34 patients (sensitivity, 97%; specificity, 100%). It also correctly demonstrated the type of dissection in all 29 patients with aortographic or surgical proof. On the other hand, computed tomography scanning, performed in 24 of 34 patients in group 1, made a correct diagnosis in only 67% of patients and misclassified the type of dissection in 33%. Transesophageal echocardiography correctly identified involvement of the coronary arteries by aortic dissection in six of seven patients as well as absence of both left and right coronary artery involvement in 10 patients with aortic dissection. This technique was also useful in detecting communications between the true and false lumens, presence of thrombi in the false lumen, and, in two patients, localized dissection rupture with formation of a false aneurysm. In both groups 1 and 2, transesophageal echocardiography correctly identified patients with moderate to severe aortic regurgitation. CONCLUSIONS: Transesophageal echocardiography is very useful in the assessment of aortic dissection.

Aortic Dissection↗
PubMed1991

Analysis and predictors of pulmonary vascular resistance after cardiac transplantation.

Elevated pulmonary vascular resistance is a known risk factor for early death from acute right ventricular failure after orthotopic cardiac transplantation. Patients in whom the elevated pulmonary vascular resistance is due primarily to increased left atrial pressure ("reactive") frequently have normalization of resistance after transplantation, but few studies have detailed the time course and magnitude of these changes. To analyze the response of pulmonary vascular resistance to cardiac transplantation, we analyzed data from 4353 right heart catheterizations on all 182 patients undergoing cardiac transplantation between 1981 and Jan. 1, 1990. Before transplantation 18% of patients had a pulmonary vascular resistance greater than 4 WU, 16% had a pulmonary artery systolic pressure greater than 60 mm Hg, and 16% had a transpulmonary gradient greater than 14 mm Hg. In the overall group of patients, pulmonary vascular resistance (mean value 2.63 WU), transpulmonary gradient (mean value 9.9 mm Hg), and pulmonary artery systolic pressure (mean value 48.0 mm Hg) were normalized within 1 week of cardiac transplantation. In patients with a high preoperative pulmonary vascular resistance (greater than or equal to 4 WU), the resistance fell promptly within 1 week of transplantation but continued to be slightly elevated throughout the period of follow-up. By multiple regression analysis, pulmonary vascular resistance at 1 week and 1 year after transplantation was significantly correlated with the pretransplantation resistance. Pulmonary vascular resistance anytime after transplantation was related to preoperative resistance, body surface area, and pulmonary artery diastolic pressure. Inferences: (1) As a group, cardiac transplant recipients have a normal pulmonary vascular resistance, transpulmonary gradient, and pulmonary artery systolic pressure within 1 week after transplantation with little change thereafter for at least several years. (2) Patients with reversible elevation of pulmonary vascular resistance before cardiac transplantation typically have a reactive and a fixed component. Cardiac transplantation relieves the reactive but not the fixed component. As a result, pulmonary vascular resistance early (within 1 week) and late after transplantation will have fallen but not completely normalized.

Cardiac Catheterization↗
PubMed1990

Controlled initial hyperkalemic reperfusion after cardiac transplantation: coronary vascular resistance and blood flow.

The coronary vascular response to controlled initial hyperkalemic reperfusion after global ischemia during cardiac transplantation was studied in 11 patients. The mean global ischemic time was 206 minutes (range, 143 to 245 minutes). All donor hearts received initial hyperkalemic crystalloid cardioplegia and subsequent oxygenated crystalloid cardioplegia during implantation. Coronary blood flow was highest during the first one to two minutes of controlled reperfusion but remained normal throughout the first ten minutes of reperfusion. Coronary vascular resistance was less than normal throughout the first ten minutes of controlled reperfusion, but there was a gradual increase throughout this period. Systemic vascular resistance remained within normal limits. The time to effective contraction was highly variable, but a greater potassium load during initial reperfusion was generally associated with a longer time to effective contraction.

Aorta↗
PubMed1990

Evidence for a central site of action to explain the negative chronotropic effect of atropine: studies on the human transplanted heart.

The chronotropic response to atropine is biphasic; low doses cause slowing of the sinus rate and high doses cause acceleration. Although it is accepted that atropine functions as a competitive antagonist at high doses, the mechanism of the negative chronotropic response at low doses is controversial. Specifically, it is unclear whether the effect is mediated centrally or peripherally. Since at the time of cardiac replacement all central nervous system connections to the heart are severed, the transplanted heart is a unique model for separating these effects. Graded doses of atropine sulfate (0.5, 1.0, 2.0, 4.0, 8.0 and 40.0 micrograms/kg body weight) were administered to 12 human heart transplant recipients to test the hypothesis that the bradycardiac effect of low dose atropine is centrally mediated. The baseline sinus cycle lengths of the decentralized donor and innervated native sinus nodes were 694 +/- 20 and 733 +/- 27 ms, respectively. At the 0.5 and 1.0 microgram/kg doses, the cycle lengths of the native sinus node increased by 29.1 +/- 13.5 and 23.1 +/- 14.2 ms, respectively. At the 2.0 micrograms/kg dose the sinus cycle length again shortened to control. At the maximal dose of atropine the sinus cycle length shortened by 138.3 +/- 29.7 ms compared with control. In contrast, the decentralized donor sinus node exhibited a flat dose response to atropine. High dose atropine (40 micrograms/kg) caused no change in the donor heart's atrial effective refractory period, corrected sinus node recovery time, or sinoatrial conduction time measured by either the Strauss or the Narula method.(ABSTRACT TRUNCATED AT 250 WORDS)

Atropine↗
PubMed1990

Gastrointestinal complications after cardiac transplantation. Potential benefit of early diagnoses and prompt surgical intervention.

Acute gastrointestinal (GI) illnesses are unusual but potentially fatal complications following cardiac transplantation. A retrospective study was performed to analyze the frequency, etiology, and severity of GI complications and the potential impact of early diagnosis and prompt surgical intervention when appropriate. Between 1981 and July 1, 1988, 31 GI complications (pancreatic, 6; colonic, 6; gastroduodenal, 6; biliary, 5; esophageal, 3; appendiceal, 2; hernia, 2; and splenic, 1) occurred in 26 patients undergoing 32 cardiac transplants. Complications were most common (14 of 31 patients, 45%) within the first 30 days after transplantation. Seventeen GI complications were treated medically (2 deaths), 2 with elective surgery and 12 with emergent operations (3 deaths). The overall mortality rate was 16%. All patients who underwent emergent operations within 3 days of onset of symptoms survived; the mean interval of onset between symptoms and operation in the nonsurvivors was 10 +/- 3.8 days. We infer that among patients requiring urgent surgical intervention, successful outcome is enhanced by intense surveillance for early symptoms, prompt diagnostic evaluation, and early surgical intervention.

Acute Disease↗