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Biomedical subjects

M J Kern

Publications and source records attributed to M J Kern.

At least 235 records · Page 13Linked to original sources
PubMed1991

Predictors of cardiac survival after percutaneous transluminal coronary angioplasty in patients with severe left ventricular dysfunction.

To assess the outcome of percutaneous transluminal coronary angioplasty (PTCA) in patients with severe left ventricular (LV) dysfunction and to determine the predictors of mortality, 73 patients with LV ejection fraction less than or equal to 40% who underwent initial PTCA were analyzed. The majority of patients had prior (greater than 1 week) myocardial infarction (62 patients, 85%). Congestive heart failure and unstable angina were present in 24 (45%) and 49 (67%) patients, respectively. Multivessel coronary artery disease was present in 60 (83%). The LV ejection fraction ranged from 14 to 40% (mean 34%). Intraaortic balloon pump (15%) and percutaneous cardiopulmonary bypass support (4%) was used infrequently. Angiographic success was obtained in 109 of 128 lesions (85%) attempted. Complete revascularization was obtained in 16 of 60 patients with clinical success. Procedure-related mortality was 5% (4 patients). All patients were followed from greater than or equal to 6 to less than or equal to 71 months (average 26). The estimated survival was 79 +/- 5%, 74 +/- 6%, 66 +/- 7% and 57 +/- 8% at 1, 2, 3 and 4 years, respectively. A Cox regression analysis revealed that the presence of congestive heart failure, a lower LV ejection fraction and a higher myocardial jeopardy score for contractile myocardium were independent predictors of survival after PTCA in patients with LV dysfunction. In conclusion, a high-risk subset can be identified among patients with severe LV dysfunction who undergo PTCA.

Angioplasty, Balloon, Coronary↗
PubMed1991

Predictors of long-term cardiac survival in patients with multivessel coronary artery disease undergoing percutaneous transluminal coronary angioplasty.

The predictors of 5-year cardiac survival in patients with multivessel coronary artery disease (CAD) undergoing percutaneous transluminal coronary angioplasty (PTCA) were analyzed in a series of 637 consecutive patients. The average age was 59 +/- 11 years in 472 men and 165 women. Diabetes mellitus, previous myocardial infarction and unstable angina were present in 119 (19%), 261 (41%) and 305 (47%) patients, respectively. Angiographically, 460 patients had 2-vessel and 177 patients had 3-vessel CAD. The left ventricular contraction score was greater than or equal to 12 in 55 patients. Angiographic success (less than 50% residual stenosis) was achieved in 85% of the 1,343 narrowings and clinical success was obtained in 526 (83%) of the 637 patients. Complete revascularization was obtained in 177 (34%) of 526 successful patients. Procedure-related complications resulted in death in 9 patients (1.4%), in Q-wave myocardial infarction only in 6 patients (0.9%) and in emergency bypass surgery in 44 patients (6.9%) (of whom 10 had Q-wave myocardial infarction). Follow-up for greater than or equal to 1 year and up to 6 years after PTCA was obtained in 608 (95%) of the 637 patients. To determine the predictors of 5-year cardiac survival, 28 clinical, angiographic and procedural variables were analyzed by Cox proportional-hazards regression. The estimated 5-year survival after PTCA was 88 +/- 2% in successful patients and 77 +/- 5% in patients in whom PTCA was unsuccessful (p less than 0.001). When clinical success was forced into the Cox regression, the left ventricular contraction score of greater than or equal to 12, diabetes mellitus and age greater than or equal to 65 years showed additional adverse effects on survival.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1991

Preliminary experience with 5 and 6 French diagnostic catheters as guiding catheters for coronary angioplasty.

With the reduction in profile of balloon dilation catheters, until recently, it has been the internal dimensions and performance of the guiding catheter that has mandated the use of 7, 8 or 9 French (F) systems for the performance of percutaneous transluminal coronary angioplasty (PTCA). A new 5F catheter design (Sherwood Medical Co., St. Louis, MO) provided a large inner lumen (0.4") permitting use of 0.20-0.22" fixed-wire PTCA balloon catheters with good coronary visualization. Potential advantages include reduced coronary artery ostial trauma and catheter induced damping and enhanced patient comfort. We report our initial experience in 14 patients undergoing PTCA with a 5 and 6F guide/fixed-wire system. Mean age was 63 +/- 10 (43-78 years). PTCA indications: Cardiogenic shock (1), post-myocardial infarction angina pectoris (2), grade III angina (5) and unstable angina pectoris (6). Vessel attempted: Left anterior descending (3), circumflex (4), obtuse marginal (2), diagonal (1), right coronary artery (3), and internal thoracic artery (1). Twelve patients had femoral approach; two brachial approach. The USCI Probe (USCI Division, Billerica, MA) was used in 8 lesions and SCIMED ACE (SCIMED Life Systems, Maplegrove, MN) catheter in 7 lesions. Successful 5 or 6F guide/fixed-wire dilations reduced the stenosis (77 +/- 14 to 37 +/- 30%) and were successfully performed in 79% (11/14). One 5F patient required 8F guiding catheter and was dilated with 2.0 fixed-wire balloon. A second failed 5F PTCA could not be dilated with any larger conventional system. A third total occlusion could not be crossed with a guidewire or fixed wire balloon. No patient had a complication.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon, Coronary↗
PubMed1991

Influence of radiographic contrast media viscosity to flow through coronary angiographic catheters.

To assess the influence of viscosity on flow resistance, 4 clinically available contrast media were injected through 12 angiographic catheters of varying dimensions at 20 degrees and 37 degrees C. Seven cc of contrast was injected at a pressure of 200 PSI at 3cc/sec by Medrad Mark IV power injector. The pressure of injection through the manifold was recorded with an electronic pressure transducer. The lowest injection pressure at 37 degrees C occurred with Hexabrix. Differences in contrast media viscosity were apparent with catheters less than 6 French diameter. There were minimal differences in injection pressures with regard to the coronary curve tip configurations for any of the contrast agents. At 20 degrees C, Isovue had lower injection pressures than the other contrast agents. Injection through 5 French catheters demonstrated a greater than 1.5 atmosphere difference, especially between Omnipaque and Hexabrix. The difference in contrast media injection pressure was greater than 2 atmospheres between 8 French guiding and 8 French diagnostic catheters and between 5 French and 6 French diagnostic catheters and less than 2 atmospheres between 8 French and 6 French diagnostic catheters. Injection pressure differences greater than 1 atmosphere were not observed for catheters of the same French size at body or room temperature contrast injection. These data indicate that important temperature related viscosity differences between agents are present and confirm that the largest differences in contrast media are most apparent for the smallest diameter catheters. Given equivalent image opacification and hemodynamic and adverse effects, selection of a low viscosity contrast media theoretically provides an advantage during procedures using small diameter catheters or interventional procedures requiring contrast media visualization through reduced channels.

Angiography↗
PubMed1991

Accordion right coronary artery: an unusual complication of PTCA guidewire entrapment.

The contour of the epicardial coronary vessels may change considerably during coronary angioplasty. We report the extreme and unique "accordion-like" wrinkling of the mid right coronary artery as a result of distal guidewire entrapment during coronary angioplasty. Recognition of this artifact and its treatment may prevent further complications of coronary angioplasty.

Aged↗
PubMed1991

Interpretation of cardiac pathophysiology from pressure waveform analysis: the left-sided V wave.

The left-sided V wave is dependent on both left atrial and ventricular pressure/volume filling relationship. The cardiac rhythm and timing of atrial systole also influences the V wave. The morphology of the V wave can reflect the severity of mitral regurgitation with stenosis, but valve areas in this setting may be better assessed by a pressure half-time method. Finally, as queried in our first patient example, V wave alternans is a reflection of left ventricular pressure alternans in a failing heart. Other signs of poor left ventricular function in Figure 1 also included an elevated minimal diastolic pressure and markedly elevated left ventricular end diastolic pressure. Hemodynamic findings of poor left ventricular function will be addressed in detail in a later "Rounds."

Aged↗
PubMed1991

Interpretation of cardiac pathophysiology from pressure waveform analysis: pacemaker hemodynamics.

The abnormal sequence of A-V contraction produces alteration of right and left heart hemodynamics reflecting the inappropriate timing of atrial contraction to ventricular filling. Some symptomatic patients may require A-V sequential pacing to improve cardiac output. The clinical effects of the atrial contribution to left ventricular function can be demonstrated by careful review of hemodynamic tracings in these individuals.

Aged↗
PubMed1991

Interpretation of cardiac pathophysiology from pressure waveform analysis: percutaneous balloon valvuloplasty.

The hemodynamic findings of aortic, mitral and pulmonary balloon valvuloplasty serve to identify classical valvular lesions and their responses to graded or abrupt catheter dilation techniques. The production of mild insufficiency after valve dilation is generally well tolerated. Severe valvular insufficiency produces the expected hemodynamic alterations, but acute decompensation may be witnessed over brief periods of time. The use of extra stiff guidewires across dilated valves, especially the aortic valve, may also produce an exaggerated hemodynamic picture of insufficiency. Although gradients may be reduced, the effect of valve dilation on aortic valve area is generally small. A discussion of factors influencing valve area calculations will be the subject of a future "Rounds."

Blood Pressure↗
PubMed1991

Interpretation of cardiac pathophysiology from pressure waveform analysis: the pulmonary valve.

Although an uncommon lesion, when pulmonary stenosis is considered, pulmonary artery and right ventricular pressures should be assessed simultaneously on two-catheter pullback to appreciate the precise location of pulmonary-right ventricular pressure gradients. The case examples demonstrate that the peripheral pulmonic stenosis can mimic pulmonary valve stenosis and that pulmonary artery insufficiency may be difficult to delineate on pressure alone (as is often the case with the hemodynamics of aortic insufficiency). These hemodynamic tracings are complemented by the echocardiographic and angiographic characterization of pulmonic valve lesions. Conduction defects or ventricular hypertrophy can affect the right ventricular pressure tracing and either delay or increase the timing of pressure rise and decline depending on the conduction disturbance and abnormality of myocardial contraction.

Adult↗