PubMed Health⌕ Search

Biomedical subjects

T M Kolettis

Publications and source records attributed to T M Kolettis.

27 records · Page 2Linked to original sources
PubMed1995

Effects of atrial, ventricular, and atrioventricular sequential pacing on coronary flow reserve.

Experimental animal data have indicated that altered left ventricular depolarization sequence as a result of right ventricular pacing may diminish coronary blood flow in the distribution of the left anterior descending coronary artery. To further investigate this, we compared the effects of atrial, ventricular, and atrioventricular (AV) sequential pacing on coronary flow reserve. Twenty-seven patients (24 male, mean age 55 +/- 7 years) with normal left anterior descending coronary arteries were studied. Coronary flow reserve was calculated as the ratio of mean flow velocity at maximal coronary vasodilatation to mean flow velocity at baseline. The study consisted of two parts. In the first part, AV sequential pacing was compared to atrial pacing at the same rate; coronary flow reserve did not differ significantly between the two pacing modes (14 patients, 4.85 +/- 1.88 vs 5.47 +/- 1.55, respectively, P > 0.05). In the second part, all three pacing modalities were compared; coronary flow reserve was significantly higher during ventricular compared to AV sequential pacing, but not significantly different compared to atrial pacing (3.69 +/- 1.42 vs 2.90 +/- 0.86 vs 3.11 +/- 0.89, respectively, P < 0.05). This difference was secondary to a significant decrease in mean baseline velocity during ventricular pacing, while mean velocity during hyperemia was comparable between the three pacing modes. It is concluded that AV sequential pacing does not appear to exert a significant effect on coronary flow reserve. Ventricular pacing, however, may lower resting coronary blood velocity in some patients, without affecting maximal coronary blood velocity, resulting in a higher coronary flow reserve.

Adult↗
PubMed1994

Prophylactic implantable cardioverter defibrillator therapy in high-risk patients with coronary artery disease.

Despite substantial progress in the management of ischemic heart disease and congestive heart failure, long-term mortality rates as a result of sudden cardiac death in such patients remain significant. Risk stratification that uses a combination of several predictors of clinical outcome has improved our ability to identify persons at high risk for future arrhythmic events. beta-Blockers and amiodarone are effective in primary prevention of sudden death in selected populations. In view of the impressive reduction in sudden death rates by implantable cardioverter defibrillators (ICDs) in patients with a history of cardiac arrest, prophylactic implantation may also be beneficial. The best way to treat these patients is not known. Three ongoing controlled clinical trials have been designed for drugs, ICDs, or both and will provide answers about whether prophylactic antiarrhythmic intervention with ICDs improves survival and whether device therapy is superior to pharmacologic treatment. Brief reports on these clinical trials are discussed in this review.

Adrenergic beta-Antagonists↗
PubMed1993

Spontaneous reversion of long-lasting chronic atrial fibrillation to sinus rhythm.

We report a case of a 72-year-old lady with rheumatic heart disease and chronic, long-lasting atrial fibrillation, who reverted spontaneously to sinus rhythm. Doppler study showed evidence of mechanical contraction of the right but not of the left atrium. This may be a sign of marked histologic changes in the atria and may require the insertion of a permanent pacemaker, because of subsequent development of sinus bradycardia.

Aged↗
PubMed1993

Short-term effects of atrial versus atrio-ventricular pacing on myocardial ischaemia in coronary artery disease patients.

This investigation was undertaken to evaluate the effects of short-term atrial vs atrio-ventricular pacing on myocardial ischaemia. The study was in two parts. In part one, 12 coronary artery disease patients were studied to investigate the effects of the two pacing modes on angina pectoris, coronary sinus O2 saturation and lactate. The two pacing modes were each applied for 5 min at 25 beats.min-1 more than the maximum heart rate of the exercise test. Coronary sinus O2 saturation and lactate were estimated before and after pacing. In part two, 13 patients with left anterior descending coronary artery disease were studied to investigate the effects of the two pacing modes on coronary flow reserve, using a Doppler catheter in the above mentioned branch after the administration of 10 mg intracoronary papaverine. The pacing rate was 15 beats.min-1 greater than the resting heart rate. Coronary sinus lactate and O2 saturation changes were the same and angina pectoris developed at about the same time from the beginning of pacing under both modes. Coronary flow reserve was 2.1 +/- 0.7 during atrial pacing and 2.1 +/- 1.1 during atrio-ventricular pacing (ns). It is concluded that short-term atrial and atrio-ventricular pacing have the same effects on myocardial ischaemia in coronary artery disease patients.

Adult↗
PubMed1990

Coronary angioplasty in patients with prior coronary artery bypass grafting.

We studied the clinical and angiographic outcome of patients with prior coronary arterial bypass grafting who underwent percutaneous transluminal coronary angioplasty at the Royal Infirmary of Edinburgh. Over a 4 year period, 47 patients with prior bypass surgery underwent angioplasty of 23 stenotic graft sites and 37 stenotic sites of native vessels. The procedure was performed a mean of 31.3 months after surgery for recurrence of symptoms refractory to maximal medical treatment. Satisfactory angiographic results were achieved in 42 patients (58 stenotic grafts or native vessels). At a median follow up period of 18 months, 20 patients were symptomatically improved, but 22 patients experienced recurrence of symptoms a mean of 4.7 months after angioplasty, despite a good initial angiographic result. Overall, 4 patients had a repeat bypass grafting and 9 patients had a repeat angioplasty. Angioplasty can be used as an alternative to a repeat operation in patients with prior bypass grafting who experience recurrence of symptoms. Initial success rates are high and complication rates low. Restenosis or development of new lesions in the native circulation, and/or in the grafts, remain significant problems. Patients with a long asymptomatic interval (greater than 6 months) between the bypass operation and recurrence of symptoms are more likely to have better long-term results after successful angioplasty, perhaps because of slower progression of atherosclerotic heart disease.

Adult↗
PubMed1990

Atrial pacing: who do we pace and what do we expect? Experiences with 100 atrial pacemakers.

The records of 100 patients with permanent atrial pacemakers implanted over a 7-year period were reviewed to assess the role and results of this mode of pacing. Indications for pacing were sick sinus syndrome in 91, carotid sinus hypersensitivity in 3, and use of an antitachycardia device in 6 patients. The mean follow-up period was 32.9 months. Symptomatic relief was good. Lead dislodgment occurred in 11 patients (usually in the first week). Threshold rises not amenable to reprogramming occurred in three patients and loss of sensing occurred in seven patients but only one required intervention. Overall, 21 patients required reoperation. The type of lead did not influence the need for reoperation that appeared to be related to the experience of the operator. Complete atrioventricular block occurred in three patients, two of whom had carotid sinus hypersensitivity and one had sick sinus syndrome. Chronic atrial fibrillation occurred in five patients, none of whom required revision of the pacemaker system. Atrial pacing is a satisfactory pacing mode in patients with sick sinus syndrome. Provided satisfactory atrioventricular conduction has been shown by incremental atrial pacing to at least 120 beats/min and carotid hypersensitivity is absent, progression to complete atrioventricular block is uncommon. Greater implanting skills are required for good results.

Adult↗
PubMedDate not supplied

Cardiac pacing and coronary hemodynamics.

This article reviews the current knowledge on the effects of pacing on coronary hemodynamics. In particular, the possible effects of heart rate, atrioventricular delay, ventricular depolarization sequence, and ventricular pacing site on the coronary circulation are examined.

Blood Flow Velocity↗
PubMedDate not supplied

Winter swimming: healthy or hazardous?. Evidence and hypotheses.

Swimming in cold water during the winter season is an extreme sport, with fans all over the world. However, its effects on health have been debated. This article examines the hypothesis that the effects of winter swimming may depend on previous exposure to cold stimuli. Immersion in cold water in unaccustomed persons may lead to detrimental consequences, while, in regular winter swimmers, adaptive physiologic mechanisms increase tolerance to cold. Furthermore, these mechanisms may prevent the occurrence of a wide variety of diseases. Prospective studies and epidemiological data are needed to test this hypothesis.

Acclimatization↗